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1
BAO, S., L. J. PIETRAFESA, NORDEN E. HUANG, Z. WU, D. A. DICKEY, P. T. GAYES, and T. YAN. "AN EMPIRICAL STUDY OF TROPICAL CYCLONE ACTIVITY IN THE ATLANTIC AND PACIFIC OCEANS: 1851–2005." Advances in Adaptive Data Analysis 03, no. 03 (July 2011): 291–307. http://dx.doi.org/10.1142/s1793536911000866.
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The trends and intrinsic frequencies in the time series of the number of Tropical Cyclones (TCs), hurricanes and typhoons, and Categories 4 and 5 hurricanes and typhoons in the Atlantic and Pacific Ocean domains, and the yearly integral of hurricane wind energy, represented by the Power Density Index (PDI), in the Atlantic and Eastern North Pacific Ocean domains are studied. The results show that the Empirical Modal Decomposition (EMD) method [Huang et al. (1998)] successfully reveals that there are intrinsic modes of variations that are controlled by climate systems such as the Quasi-Biennial Oscillation (QBO), the El Nino Southern Oscillation (ENSO), and the Atlantic and Pacific Multi-Decadal Oscillations (AMO and PDO), along with the Meridional Overturning Circulation (MOC). It also reveals some oscillation modes whose controlling factors are not yet identified. In both the Atlantic and Pacific Ocean domains, the frequencies of TCs, hurricane/typhoon-strength TCs and the strongest (Saffir-Simpson Categories 4 and 5) TCs have slowly rising trends. In the Atlantic Ocean, our study indicates that since the mid-1970s, the observed rise in the number of the strongest (Cats. 4 and 5) TCs as discussed previously by Webster et al. [2005] and the rise in the measure of destructiveness, the Power Density Index (PDI), developed by Emanuel [2005], were not the cause of rising trends, but instead, they are the result of the combination of positive phases of several intrinsic frequency modes. In the Pacific Ocean, the rising trends have larger amplitudes than those in the Atlantic Ocean, but the higher frequency modes appear to play a more important role in deciding the year-to-year Pacific TC, hurricane/typhoon and Cats. 4 and 5 TC activity levels.
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Murakami, H., E. Levin, T. L. Delworth, R. Gudgel, and P. C. Hsu. "Dominant effect of relative tropical Atlantic warming on major hurricane occurrence." Science 362, no. 6416 (September 27, 2018): 794–99. http://dx.doi.org/10.1126/science.aat6711.
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Here we explore factors potentially linked to the enhanced major hurricane activity in the Atlantic Ocean during 2017. Using a suite of high-resolution model experiments, we show that the increase in 2017 major hurricanes was not primarily caused by La Niña conditions in the Pacific Ocean but rather triggered mainly by pronounced warm sea surface conditions in the tropical North Atlantic. Further, we superimpose a similar pattern of North Atlantic surface warming on data for long-term increasing sea surface temperature (a product of increases in greenhouse gas concentrations and decreases in aerosols) to show that this warming trend will likely lead to even higher numbers of major hurricanes in the future. The key factor controlling Atlantic major hurricane activity appears to be the degree to which the tropical Atlantic warms relative to the rest of the global ocean.
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Avila, Lixion A., and Jamie Rhome. "Eastern North Pacific Hurricane Season of 2007." Monthly Weather Review 137, no. 8 (August 1, 2009): 2436–47. http://dx.doi.org/10.1175/2009mwr2915.1.
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Abstract The hurricane season of 2007 in the eastern North Pacific Ocean basin is summarized, individual tropical cyclones are described, and a forecast verification is presented. The 2007 eastern North Pacific season was not an active one. There were 11 tropical storms, of which only 4 became hurricanes. Only one cyclone became a major hurricane. One hurricane struck Mexico and one tropical storm made landfall near the Guatemala–Mexico border. The 2007 National Hurricane Center forecast track errors were lower than the previous 5-yr means at all forecast lead times, and especially so for the 72-, 96-, and 120-h periods when the errors were 16%, 22%, and 20% lower, respectively. The official intensity forecasts had only limited skill.
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Murakami, Hiroyuki, Gabriel A. Vecchi, Thomas L. Delworth, Andrew T. Wittenberg, Seth Underwood, Richard Gudgel, Xiaosong Yang, et al. "Dominant Role of Subtropical Pacific Warming in Extreme Eastern Pacific Hurricane Seasons: 2015 and the Future." Journal of Climate 30, no. 1 (January 2017): 243–64. http://dx.doi.org/10.1175/jcli-d-16-0424.1.
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The 2015 hurricane season in the eastern and central Pacific Ocean (EPO and CPO), particularly around Hawaii, was extremely active, including a record number of tropical cyclones (TCs) and the first instance of three simultaneous category-4 hurricanes in the EPO and CPO. A strong El Niño developed during the 2015 boreal summer season and was attributed by some to be the cause of the extreme number of TCs. However, according to a suite of targeted high-resolution model experiments, the extreme 2015 EPO and CPO hurricane season was not primarily induced by the 2015 El Niño tropical Pacific warming, but by warming in the subtropical Pacific Ocean. This warming is not typical of El Niño, but rather of the Pacific meridional mode (PMM) superimposed on long-term anthropogenic warming. Although the likelihood of such an extreme year depends on the phase of natural variability, the coupled GCM projects an increase in the frequency of such extremely active TC years over the next few decades for EPO, CPO, and Hawaii as a result of enhanced subtropical Pacific warming from anthropogenic greenhouse gas forcing.
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Ford, Victoria L., Nan D. Walker, and Iam-Fei Pun. "Anomalous Oceanic Conditions in the Central and Eastern North Pacific Ocean during the 2014 Hurricane Season and Relationships to Three Major Hurricanes." Journal of Marine Science and Engineering 8, no. 4 (April 17, 2020): 288. http://dx.doi.org/10.3390/jmse8040288.
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The 2014 Northeast Pacific hurricane season was highly active, with above-average intensity and frequency events, and a rare landfalling Hawaiian hurricane. We show that the anomalous northern extent of sea surface temperatures and anomalous vertical extent of upper ocean heat content above 26 °C throughout the Northeast and Central Pacific Ocean may have influenced three long-lived tropical cyclones in July and August. Using a variety of satellite-observed and -derived products, we assess genesis conditions, along-track intensity, and basin-wide anomalous upper ocean heat content during Hurricanes Genevieve, Iselle, and Julio. The anomalously northern surface position of the 26 °C isotherm beyond 30° N to the north and east of the Hawaiian Islands in 2014 created very high sea surface temperatures throughout much of the Central Pacific. Analysis of basin-wide mean conditions confirm higher-than-average storm activity during strong positive oceanic thermal anomalies. Positive anomalies of 15–50 kJ cm−2 in the along-track upper ocean heat content for these three storms were observed during the intensification phase prior to peak intensity, advocating for greater understanding of the ocean thermal profile during tropical cyclone genesis and development.
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Murakami, Hiroyuki, Gabriel A. Vecchi, Gabriele Villarini, Thomas L. Delworth, Richard Gudgel, Seth Underwood, Xiaosong Yang, Wei Zhang, and Shian-Jiann Lin. "Seasonal Forecasts of Major Hurricanes and Landfalling Tropical Cyclones using a High-Resolution GFDL Coupled Climate Model." Journal of Climate 29, no. 22 (October 21, 2016): 7977–89. http://dx.doi.org/10.1175/jcli-d-16-0233.1.
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Abstract Skillful seasonal forecasting of tropical cyclone (TC; wind speed ≥17.5 m s−1) activity is challenging, even more so when the focus is on major hurricanes (wind speed ≥49.4 m s−1), the most intense hurricanes (category 4 and 5; wind speed ≥58.1 m s–1), and landfalling TCs. This study shows that a 25-km-resolution global climate model [High-Resolution Forecast-Oriented Low Ocean Resolution (FLOR) model (HiFLOR)] developed at the Geophysical Fluid Dynamics Laboratory (GFDL) has improved skill in predicting the frequencies of major hurricanes and category 4 and 5 hurricanes in the North Atlantic as well as landfalling TCs over the United States and Caribbean islands a few months in advance, relative to its 50-km-resolution predecessor climate model (FLOR). HiFLOR also shows significant skill in predicting category 4 and 5 hurricanes in the western North Pacific and eastern North Pacific, while both models show comparable skills in predicting basin-total and landfalling TC frequency in the basins. The improved skillful forecasts of basin-total TCs, major hurricanes, and category 4 and 5 hurricane activity in the North Atlantic by HiFLOR are obtained mainly by improved representation of the TCs and their response to climate from the increased horizontal resolution rather than by improvements in large-scale parameters.
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Lee, Sang-Ki, David B. Enfield, and Chunzai Wang. "Future Impact of Differential Interbasin Ocean Warming on Atlantic Hurricanes." Journal of Climate 24, no. 4 (February 15, 2011): 1264–75. http://dx.doi.org/10.1175/2010jcli3883.1.
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Abstract Global climate model simulations forced by future greenhouse warming project that the tropical North Atlantic (TNA) warms at a slower rate than the tropical Indo-Pacific in the twenty-first century, consistent with their projections of a weakened Atlantic thermohaline circulation. Here, an atmospheric general circulation model is used to advance a consistent physical rationale that the suppressed warming of the TNA increases the vertical wind shear and static stability aloft in the main development region (MDR) for Atlantic hurricanes, and thus decreases overall Atlantic hurricane activity in the twenty-first century. A carefully designed suite of model experiments illustrates that the preferential warming of the tropical Indo-Pacific induces a global average warming of the tropical troposphere, via a tropical teleconnection mechanism, and thus increases atmospheric static stability and decreases convection over the suppressed warming region of the TNA. The anomalous diabatic cooling, in turn, forces the formation of a stationary baroclinic Rossby wave northwest of the forcing region, consistent with Gill’s simple model of tropical atmospheric circulations, in such a way as to induce a secular increase of the MDR vertical wind shear. However, a further analysis indicates that the net effect of future greenhouse warming on the MDR vertical wind shear is less than the observed multidecadal swing of the MDR vertical wind shear in the twentieth century. Thus, it is likely that the Atlantic multidecadal oscillation will still play a decisive role over the greenhouse warming in the fate of Atlantic hurricane activity throughout the twenty-first century under the assumption that the twenty-first-century changes in interbasin SST difference, projected by the global climate model simulations, are accurate.
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Jury, Mark R., and David B. Enfield. "Environmental Patterns Associated with Active and Inactive Caribbean Hurricane Seasons." Journal of Climate 23, no. 8 (April 15, 2010): 2146–60. http://dx.doi.org/10.1175/2009jcli3201.1.
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Abstract This study of hurricanes passing through the Caribbean in the 1950–2005 period reveals that seasons with more intense hurricanes occur with the onset of Pacific La Niña events and when Atlantic SSTs west of Africa are above normal. Composites of NCEP reanalysis fields with regard to Caribbean hurricanes reveal development of an anomalous equatorial Atlantic zonal overturning circulation (upper easterly/lower westerly) that shifts toward the Caribbean coincident with a westward spread of the cold tongue in the east Pacific. Ocean–atmosphere coupling is promoted through interaction of the southern Hadley cell and the Atlantic ITCZ. A heat budget analysis suggests that evaporation governs SSTs in the major development region (MDR) and near Venezuela, but the signal is weak prior to May. Using the knowledge gained, statistical algorithms are developed to predict Caribbean hurricanes at seasonal lead times. These make use of equatorial Pacific SST, subtropical Atlantic SST, and the zonal Walker cell over the Atlantic.
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Lawrimore, Jay H., Michael S. Halpert, Gerald D. Bell, Matthew J. Menne, Bradfield Lyon, Russell C. Schnell, Karin L. Gleason, et al. "Climate Assessment for 2000." Bulletin of the American Meteorological Society 82, no. 6s (June 1, 2001): S1—S56. http://dx.doi.org/10.1175/0003-0007-82.6.s1.
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The global climate in 2000 was again influenced by the long-running Pacific cold episode (La Niña) that began in mid-1998. Consistent with past cold episodes, enhanced convection occurred across the climatologically convective regions of Indonesia and the western equatorial Pacific, while convection was suppressed in the central Pacific. The La Niña was also associated with a well-defined African easterly jet located north of its climatological mean position and low vertical wind shear in the tropical Atlantic and Caribbean, both of which contributed to an active North Atlantic hurricane season. Precipitation patterns influenced by typical La Niña conditions included 1) above-average rainfall in southeastern Africa, 2) unusually heavy rainfall in northern and central regions of Australia, 3) enhanced precipitation in the tropical Indian Ocean and western tropical Pacific, 4) little rainfall in the central tropical Pacific, 5) below-normal precipitation over equatorial east Africa, and 6) drier-than-normal conditions along the Gulf coast of the United States. Although no hurricanes made landfall in the United States in 2000, another active North Atlantic hurricane season featured 14 named storms, 8 of which became hurricanes, with 3 growing to major hurricane strength. All of the named storms over the North Atlantic formed during the August–October period with the first hurricane of the season, Hurricane Alberto, notable as the third-longest-lived tropical system since reliable records began in 1945. The primary human loss during the 2000 season occurred in Central America, where Hurricane Gordon killed 19 in Guatemala, and Hurricane Keith killed 19 in Belize and caused $200 million dollars of damage. Other regional events included 1) record warm January–October temperatures followed by record cold November–December temperatures in the United States, 2) extreme drought and widespread wildfires in the southern and western Unites States, 3) continued long-term drought in the Hawaiian Islands throughout the year with record 24-h rainfall totals in November, 4) deadly storms and flooding in western Europe in October, 5) a summer heat wave and drought in southern Europe, 6) monsoon flooding in parts of Southeast Asia and India, 7) extreme winter conditions in Mongolia, 8) extreme long-term drought in the Middle East and Southwest Asia, and 9) severe flooding in southern Africa. Global mean temperatures remained much above average in 2000. The average land and ocean temperature was 0.39°C above the 1880–1999 long-term mean, continuing a trend to warmer-than-average temperatures that made the 1990s the warmest decade on record. While the persistence of La Niña conditions in 2000 was associated with somewhat cooler temperatures in the Tropics, temperatures in the extratropics remained near record levels. Land surface temperatures in the high latitudes of the Northern Hemisphere were notably warmer than normal, with annually averaged anomalies greater than 2°C in parts of Alaska, Canada, Asia, and northern Europe.
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Bender, Morris A., Isaac Ginis, Robert Tuleya, Biju Thomas, and Timothy Marchok. "The Operational GFDL Coupled Hurricane–Ocean Prediction System and a Summary of Its Performance." Monthly Weather Review 135, no. 12 (December 1, 2007): 3965–89. http://dx.doi.org/10.1175/2007mwr2032.1.
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Abstract The past decade has been marked by significant advancements in numerical weather prediction of hurricanes, which have greatly contributed to the steady decline in forecast track error. Since its operational implementation by the U.S. National Weather Service (NWS) in 1995, the best-track model performer has been NOAA’s regional hurricane model developed at the Geophysical Fluid Dynamics Laboratory (GFDL). The purpose of this paper is to summarize the major upgrades to the GFDL hurricane forecast system since 1998. These include coupling the atmospheric component with the Princeton Ocean Model, which became operational in 2001, major physics upgrades implemented in 2003 and 2006, and increases in both the vertical resolution in 2003 and the horizontal resolution in 2002 and 2005. The paper will also report on the GFDL model performance for both track and intensity, focusing particularly on the 2003 through 2006 hurricane seasons. During this period, the GFDL track errors were the lowest of all the dynamical model guidance available to the NWS Tropical Prediction Center in both the Atlantic and eastern Pacific basins. It will also be shown that the GFDL model has exhibited a steady reduction in its intensity errors during the past 5 yr, and can now provide skillful intensity forecasts. Tests of 153 forecasts from the 2004 and 2005 Atlantic hurricane seasons and 75 forecasts from the 2005 eastern Pacific season have demonstrated a positive impact on both track and intensity prediction in the 2006 GFDL model upgrade, through introduction of a cloud microphysics package and an improved air–sea momentum flux parameterization. In addition, the large positive intensity bias in sheared environments observed in previous versions of the model is significantly reduced. This led to the significant improvement in the model’s reliability and skill for forecasting intensity that occurred in 2006.
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Amador, Jorge A., A. M. Durán-Quesada, E. R. Rivera, G. Mora, F. Sáenz, B. Calderón, and N. Mora. "The easternmost tropical Pacific. Part II: Seasonal and intraseasonal modes of atmospheric variability." Revista de Biología Tropical 64, no. 1 (March 2, 2016): 23. http://dx.doi.org/10.15517/rbt.v64i1.23409.
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<p>This is Part II of a two-part review about climate and climate variability focused on the Eastern Tropical Pacific (ETP) and the Caribbean Sea (CS). Both parts are aimed at providing oceanographers, marine biologists, and other ocean scientists, a guiding base for ocean-atmosphere interaction processes affecting the CS, the ETP, and the waters of Isla del Coco. Isla del Coco National Park is a Costa Rican World Heritage site. Part I analyzed the mean fields for both basins and a larger region covering 25º S - 35º N, 20º W - 130º W. Here we focus on a smaller area (65º W - 95º W, 0º - 20º N), as a complement to Part 1. Incoming solar radiation and surface energy fluxes reveal the complex nature of the ETP and CS for convective activity and precipitation on seasonal and intraseasonal time scales. Both regions are relevant as sources of evaporation and the associated moisture transport processes. The American Monsoon System influences the climate and climate variability of the ETP and CS, however, the precise way systems affect regional precipitation and transport of moisture, within the Intra Americas Sea (IAS) are not clear. Although the Caribbean Low-Level Jet (CLLJ) is known to act as a conveyor belt for moisture transport, intraseasonal and seasonal modes of the CLLJ and their interactions with other IAS systems, have to be further investigated. Trans-isthmic jets, exert a variable seasonal wind stress force over the ocean surface co-generating regions of great marine productivity. Isolated convection, the seasonal migration of the Intertropical Convergence Zone, the hurricane season, the Mid-Summer Drought, the seasonal and intraseasonal behavior of low-level jets and their interactions with transients, and the southward incursion of cold fronts contribute to regional seasonal precipitation. Many large-scale systems, such as El Niño-Southern Oscillation, the Atlantic Multidecadal Oscillation and the Madden-Julian Oscillation (MJO, also influence the variability of precipitation by modulating regional features associated with convection and precipitation. Monthly tropical storm (TS) activity in the CS and ETP basins is restricted to the period May-November, with very few cases in December. The CS presents TS peak activity during August, as well as for the number of hurricanes and major hurricanes, in contrast to the ETP that shows the same features during September.</p><div> </div>
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Fan, Yalin, Isaac M. Held, Shian-Jiann Lin, and Xiaolan L. Wang. "Ocean Warming Effect on Surface Gravity Wave Climate Change for the End of the Twenty-First Century." Journal of Climate 26, no. 16 (August 6, 2013): 6046–66. http://dx.doi.org/10.1175/jcli-d-12-00410.1.
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Abstract Surface wind (U10) and significant wave height (Hs) response to global warming are investigated using a coupled atmosphere–wave model by perturbing the sea surface temperatures (SSTs) with anomalies generated by the Working Group on Coupled Modeling (WGCM) phase 3 of the Coupled Model Intercomparison Project (CMIP3) coupled models that use the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4)/Special Report on Emissions Scenarios A1B (SRES A1B) scenario late in the twenty-first century. Several consistent changes were observed across all four realizations for the seasonal means: robust increase of U10 and Hs in the Southern Ocean for both the austral summer and winter due to the poleward shift of the jet stream; a dipole pattern of the U10 and Hs with increases in the northeast sector and decreases at the midlatitude during boreal winter in the North Atlantic due to the more frequent occurrence of the positive phases of the North Atlantic Oscillation (NAO); and strong decrease of U10 and Hs in the tropical western Pacific Ocean during austral summer, which might be caused by the joint effect of the weakening of the Walker circulation and the large hurricane frequency decrease in the South Pacific. Changes of the 99th percentile U10 and Hs are twice as strong as changes in the seasonal means, and the maximum changes are mainly dominated by the changes in hurricanes. Robust strong decreases of U10 and Hs in the South Pacific are obtained because of the large hurricane frequency decrease, while the results in the Northern Hemisphere basins differ among the models. An additional sensitivity experiment suggests that the qualitative response of U10 and Hs is not affected by using SST anomalies only and maintaining the radiative forcing unchanged (using 1980 values), as in this study.
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DÍEZ, C. M., and C. J. SOLANO. "LINEARIZATION OF RELATIVE HUMIDITY OVER THE PACIFIC OCEAN ON THE EQUATORIAL LINE." Periódico Tchê Química 16, no. 33 (March 20, 2019): 630–40. http://dx.doi.org/10.52571/ptq.v16.n33.2019.645_periodico33_pgs_630_640.pdf.
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The atmosphere system is ruled by the interaction of many meteorological parameters, causing a dependency between them, i.e., moisture and temperature, both suitable in front of any anomaly, such as storms, hurricanes, El Niño-Southern Oscillation (ENSO) events. So, understanding perturbations of the variation of moistness along the time may provide an indicator of any oceanographic phenomenon. Annual relative humidity data around the Equatorial line of the Pacific Ocean were processed and analyzed to comprehend the time evolution of each dataset, appreciate anomalies, trends, histograms, and propose a way to predict anomalous episodes such ENSO events, observing abnormality of lag correlation coefficients between every pair of buoys. Datasets were taken from the Tropical Atmosphere Ocean / Triangle Trans-Ocean Network (TAO/TRITON) project, array directed by Pacific Environmental Laboratory (PMEL) of the National Oceanic and Atmospheric Administration (NOAA), and the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). All the datasets were processed, and the code was elaborated by the author or adapted from Mathworks Inc. Even occurrences of relative humidity in the east side of the Pacific Ocean seem to oscillate harmonically, while occurrences in the west side, do not, because of the size of their amplitudes of oscillations. This fact can be seen in the histograms that show Peak shapes in the east side of the ocean, and Gaussians in the west; lag correlation functions show that no one pair of buoys synchronize fluctuations, but western buoys are affected in front of ENSO events, especially between 1997-98. Definitely, lag correlations in western buoys are determined to detect ENSO events.
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Wang, H., X. Zou, and G. Li. "An Improved Quality Control for AIRS Total Column Ozone Observations within and around Hurricanes." Journal of Atmospheric and Oceanic Technology 29, no. 3 (March 1, 2012): 417–32. http://dx.doi.org/10.1175/jtech-d-11-00108.1.
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Abstract Atmospheric Infrared Sounder (AIRS) provides twice-daily global observations from which total column ozone data can be retrieved. However, 20% ~ 30% of AIRS ozone data are flagged to be of bad quality. Most of the flagged data were identified to have total precipitable water (PW) errors, defined by the ratio between PW errors and PW retrieval exceeding 35%. It was found that most data within hurricanes were flagged because of extremely low total PW, which is also retrieved from AIRS observations. In this study, a new PW ratio, defined by the AIRS PW error divided by the National Centers for Environmental Prediction (NCEP) zonal average PW, is used to replace the one in AIRS quality control (QC) scheme. Data are removed if the new PW error ratio exceeds 33%. Only 5% ~ 10% of AIRS ozone data are flagged to be of bad quality. Following this step of QC, a linear regression model, which links the total column ozone to the model’s vertical mean potential vorticity (MPV), is established for future data assimilation of AIRS total ozone. Outliers identified by a biweight algorithm are further removed. Numerical results implementing the proposed QC method are compared with those provided by AIRS for Typhoon Sinlaku (2008) in the Pacific Ocean and Hurricane Earl (2010) in the Atlantic Ocean. It is shown that the new scheme works by retaining more of the good data while still removing the bad data.
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Wu, Liguang, Li Tao, and Qinghua Ding. "Influence of Sea Surface Warming on Environmental Factors Affecting Long-Term Changes of Atlantic Tropical Cyclone Formation." Journal of Climate 23, no. 22 (November 15, 2010): 5978–89. http://dx.doi.org/10.1175/2010jcli3384.1.
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Abstract Despite the observed high correlation between the Atlantic sea surface temperature (SST) and the Atlantic tropical cyclone (TC) activity, interpretation of this relationship remains uncertain. This study suggests that the tropical Atlantic sea surface warming induces a pair of anomalous low-level cyclones on each side of the equator, providing favorable conditions for enhancing TC formation east of 45°W, while the effect of SST warming in the tropical Indian Ocean and Pacific Ocean tends to suppress the TC formation. Over the past 30 years (1978–2007), the TC activity in the Atlantic basin is characterized with significant enhancement of TC formation east of 45°W, where the total TC number increased significantly compared to the period 1948–77. Despite the possible undercount of TCs, this study shows that the recently enhanced TC formation may not be totally accounted for by the poor TC observing network prior to the satellite era. The Atlantic sea surface warming that occurred in recent decades might have allowed more TCs to form, to form earlier, and to take a longer track, while the effect is partially offset by the SST warming in Indian and Pacific Oceans. This study suggests that the close relationship between the Atlantic SST and TC activity over the past 30 years, including basinwide increases in the average lifetime, annual frequency, proportion of intense hurricanes, and annual accumulated power dissipation index (PDI), as reported in previous studies, is mainly a result of the SST warming in the tropical Atlantic exceeding that in the tropical Indian and Pacific Oceans. The results agree with recent argument that the relative Atlantic SST change or the SST difference between the tropical Atlantic and other oceans play an important role in controlling long-term TC activity in the Atlantic basin.
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Zhang, Xuejin, Sundararaman G. Gopalakrishnan, Samuel Trahan, Thiago S. Quirino, Qingfu Liu, Zhan Zhang, Ghassan Alaka, and Vijay Tallapragada. "Representing Multiple Scales in the Hurricane Weather Research and Forecasting Modeling System: Design of Multiple Sets of Movable Multilevel Nesting and the Basin-Scale HWRF Forecast Application." Weather and Forecasting 31, no. 6 (December 1, 2016): 2019–34. http://dx.doi.org/10.1175/waf-d-16-0087.1.
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Abstract In this study, the design of movable multilevel nesting (MMLN) in the Hurricane Weather Research and Forecasting (HWRF) modeling system is documented. The configuration of a new experimental HWRF system with a much larger horizontal outer domain and multiple sets of MMLN, referred to as the “basin scale” HWRF, is also described. The performance of this new system is applied for various difficult forecast scenarios such as 1) simulating multiple storms [i.e., Hurricanes Earl (2010), Danielle (2010), and Frank (2010)] and 2) forecasting tropical cyclone (TC) to extratropical cyclone transitions, specifically Hurricane Sandy (2012). Verification of track forecasts for the 2011–14 Atlantic and eastern Pacific hurricane seasons demonstrates that the basin-scale HWRF produces similar overall results to the 2014 operational HWRF, the best operational HWRF at the same resolution. In the Atlantic, intensity forecasts for the basin-scale HWRF were notably worse than for the 2014 operational HWRF, but this deficiency was shown to be from poor intensity forecasts for Hurricane Leslie (2012) associated with the lack of ocean coupling in the basin-scale HWRF. With Leslie removed, the intensity forecast errors were equivalent. The basin-scale HWRF is capable of predicting multiple TCs simultaneously, allowing more realistic storm-to-storm interactions. Even though the basin-scale HWRF produced results only comparable to the regular operational HWRF at this stage, this configuration paves a promising pathway toward operations.
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KERR, ALEXANDER M. "Defoliation of an island (Guam, Mariana Archipelago, Western Pacific Ocean) following a saltspray-laden ‘dry’ typhoon." Journal of Tropical Ecology 16, no. 6 (November 2000): 895–901. http://dx.doi.org/10.1017/s0266467400001796.
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Tropical cyclonic storms with sustained winds above 120 km h−1 are called hurricanes, typhoons or cyclones depending on their geographic location. They can cause considerable damage to forests. This damage may be in the form of pruned and fallen trees from intense winds (Boucher et al. 1990, Walker et al. 1992), defoliation from a combination of winds and torrential rains (Vandermeer et al. 1997), or mortality from marine inundation of low-lying land (Gardner et al. 1991). Occasionally, extensive defoliation of forests can also occur from wind-driven saltwater when winds are onshore and precipitation is insufficient to dilute the seaspray (Chen & Horng 1993). Below I report the dramatic consequences of an unusual seaspray-laden typhoon on the vegetation of the western Micronesian island of Guam.
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Lloyd, Ian D., and Gabriel A. Vecchi. "Observational Evidence for Oceanic Controls on Hurricane Intensity." Journal of Climate 24, no. 4 (February 15, 2011): 1138–53. http://dx.doi.org/10.1175/2010jcli3763.1.
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Abstract The influence of oceanic changes on tropical cyclone activity is investigated using observational estimates of sea surface temperature (SST), air–sea fluxes, and ocean subsurface thermal structure during the period 1998–2007. SST conditions are examined before, during, and after the passage of tropical cyclones, through Lagrangian composites along cyclone tracks across all ocean basins, with particular focus on the North Atlantic. The influence of translation speed is explored by separating tropical cyclones according to the translation speed divided by the Coriolis parameter. On average for tropical cyclones up to category 2, SST cooling becomes larger as cyclone intensity increases, peaking at 1.8 K in the North Atlantic. Beyond category 2 hurricanes, however, the cooling no longer follows an increasing monotonic relationship with intensity. In the North Atlantic, the cooling for stronger hurricanes decreases, while in other ocean basins the cyclone-induced cooling does not significantly differ from category 2 to category 5 tropical cyclones, with the exception of the South Pacific. Since the SST response is nonmonotonic, with stronger cyclones producing more cooling up to category 2, but producing less or approximately equal cooling for categories 3–5, the observations indicate that oceanic feedbacks can inhibit intensification of cyclones. This result implies that large-scale oceanic conditions are a control on tropical cyclone intensity, since they control oceanic sensitivity to atmospheric forcing. Ocean subsurface thermal data provide additional support for this dependence, showing weaker upper-ocean stratification for stronger tropical cyclones. Intensification is suppressed by strong ocean stratification since it favors large SST cooling, but the ability of tropical cyclones to intensify is less inhibited when stratification is weak and cyclone-induced SST cooling is small. Thus, after accounting for tropical cyclone translation speeds and latitudes, it is argued that reduced cooling under extreme tropical cyclones is the manifestation of the impact of oceanic conditions on the ability of tropical cyclones to intensify.
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Wang, Xinxi, and Haiyan Jiang. "Contrasting Behaviors between the Rapidly Intensifying and Slowly Intensifying Tropical Cyclones in the North Atlantic and Eastern Pacific Basins." Journal of Climate 34, no. 3 (February 2021): 987–1003. http://dx.doi.org/10.1175/jcli-d-19-0908.1.
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AbstractBased on 35-yr (1982–2016) best track and Statistical Hurricane Intensity Prediction Scheme data, this study examined climatology of rapidly intensifying (RI) and slowly intensifying (SI) events as well as their time evolutions of storm-related and environmental parameters for tropical cyclones (TCs) in both North Atlantic (AL) and eastern North Pacific (EP) basins. Major hurricanes were intensified mainly through RI while tropical depression and tropical storms were intensified through SI. The percentage of TCs that underwent RI peaks in the late hurricane season whereas the percentage of TCs that underwent SI peaks early. For the first time in the literature, this study found that RI events have significantly different storm-related and environmental characteristics than SI events for before-, during-, and after-event stages. In both AL and EP basins, RI events always intensify significantly faster during the previous 12 h, are located farther south, and have warmer sea surface and 200-hPa temperatures, greater ocean heat content, larger 200-hPa divergence, weaker vertical wind shear, and weaker 200-hPa westerly flow than SI events for all event-relative stages. In the AL basin, RI events have larger low-level and midlevel relative humidity and larger 850-hPa relative vorticity than SI events for all event-relative stages in the AL and most event-relative stages in the EP. RI events are associated with more convectively unstable atmosphere and are farther away from their maximum potential intensities than SI events for most event-relative stages in the AL and for all event-relative stages in the EP.
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Wang, Chunzai, David B. Enfield, Sang-ki Lee, and Christopher W. Landsea. "Influences of the Atlantic Warm Pool on Western Hemisphere Summer Rainfall and Atlantic Hurricanes." Journal of Climate 19, no. 12 (June 15, 2006): 3011–28. http://dx.doi.org/10.1175/jcli3770.1.
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Abstract The Atlantic warm pool (AWP) of water warmer than 28.5°C comprises the Gulf of Mexico, the Caribbean Sea, and the western tropical North Atlantic (TNA). The AWP reaches its maximum size around September, with large AWPs being almost 3 times larger than small ones. Although ENSO teleconnections are influential on the AWP, about two-thirds of the large and small AWP variability appears unrelated to ENSO. The AWP is usually geographically different from the TNA; however, the AWP size is correlated with the TNA SST anomalies. During August to October, large AWPs and warm TNA are associated with increased rainfall over the Caribbean, Mexico, the eastern subtropical Atlantic, and the southeast Pacific, and decreased rainfall in the northwest United States, Great Plains, and eastern South America. In particular, rainfall in the Caribbean, Central America, and eastern South America from August to October is mainly related to the size of the AWP. Large (small) AWPs and warm (cold) TNA correspond to a weakening (strengthening) of the northward surface winds from the AWP to the Great Plains that disfavors (favors) moisture transport for rainfall over the Great Plains. On the other hand, large (small) AWPs and warm (cold) TNA strengthen (weaken) the summer regional Atlantic Hadley circulation that emanates from the warm pool region into the southeast Pacific, changing the subsidence over the southeast Pacific and thus the stratus cloud and drizzle there. The large AWP, associated with a decrease in sea level pressure and an increase in atmospheric convection and cloudiness, corresponds to a weak tropospheric vertical wind shear and a deep warm upper ocean, and thus increases Atlantic hurricane activity.
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Patla, Jason E., Duane Stevens, and Gary M. Barnes. "A Conceptual Model for the Influence of TUTT Cells on Tropical Cyclone Motion in the Northwest Pacific Ocean." Weather and Forecasting 24, no. 5 (October 1, 2009): 1215–35. http://dx.doi.org/10.1175/2009waf2222181.1.
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Abstract Eleven (10 Pacific, 1 Atlantic) tropical cyclones (TCs), which include typhoons/hurricanes and tropical storms, are examined using the latest 40-yr ECMWF Re-Analysis (ERA-40) dataset and Joint Typhoon Warning Center (JTWC) best-track data to determine if and how tropical upper-tropospheric trough (TUTT) cells influence TC tracks. This type of interaction has led to rather large TC track forecast errors at 72 h (2000+ km) in the northwest Pacific and is often ignored or poorly forecast due to inadequate numerical model TUTT cell predictions. Ten selected cases out of the initial 25 potential Pacific cases exhibited a “nonstandard” TC track; a TUTT cell was the sole large-scale transient feature within 2000 km of the TC’s center, and the TC intensity was >17 m s−1. The circulations’ separation distance, orientation, intensity, and TUTT cell’s closed circulation size are critical characteristics in determining the likelihood of a TUTT cell influencing a TC track. Interactions occur at distances greater than 1700 km, continue for periods from 24 to 48 h, and occur 2–3 times per year in the NW Pacific. Examination of the TC’s tropospheric winds’ deep layer mean (100–1000 hPa), and upper (100–500 hPa), middle (300–850 hPa), and lower (500–1000 hPa) layers, along with various quadrants of the upper layer, demonstrate a link between the TUTT cell’s wind field and the nonstandard TC tracks. A conceptual model of how a TUTT cell can influence TC track is presented. The model provides decision-grade operational guidance for TC forecasters using pattern recognition scenarios. Application of the conceptual model at the JTWC is currently under way.
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Hsiao, Shih-Chun, Tien-Hung Hou, Tai-Wen Hsu, and Chia-Cheng Tsai. "Using multiple-resolution data in an adaptive simulation for typhoon-induced waves in northwest Pacific Ocean." Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment 234, no. 1 (February 13, 2019): 284–97. http://dx.doi.org/10.1177/1475090219826756.
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Due to the very large expanse of warm water in the northwest Pacific Ocean, typhoons are stronger and occur more frequently than hurricanes. In addition, there is usually a lack of unified high-resolution data of wind fields and bathymetry since multiple countries can be influenced by a typhoon. Therefore, we use multiple-resolution data in an adaptive simulation for typhoon-induced waves. Higher-resolution data are obtained from the government of Taiwan and are used for the area around Taiwan. In the other area, lower resolution data are adopted from the National Oceanic and Atmospheric Administration of the United States. An adaption criterion is implemented such that the highest resolution numerical grids move with the typhoon in a large-scale simulation. The numerical results obtained by the large-scale simulation with multiple-resolution wind fields are improved over those obtained by a smaller scale simulation with the higher resolution wind field at buoys near Taiwan. In addition, the large-scale simulation also provides results for buoys where the higher resolution wind field is not available. In addition, a speedup of fourfolds by the dynamic adaption model over the partially uniform grid one is demonstrated.
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Loridan, T., E. Scherer, M. Dixon, E. Bellone, and S. Khare. "Cyclone Wind Field Asymmetries during Extratropical Transition in the Western North Pacific." Journal of Applied Meteorology and Climatology 53, no. 2 (February 2014): 421–28. http://dx.doi.org/10.1175/jamc-d-13-0257.1.
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AbstractRisk-assessment systems for wind hazards (e.g., hurricanes or typhoons) often rely on simple parametric wind field formulations. They are built using extensive observations of tropical cyclones and make assumptions about wind field asymmetry. In this framework, maximum winds are always simulated to the right of the cyclone, but analysis of the Climate Forecast System Reanalysis database for the western North Pacific Ocean suggests that wind fields from cyclones undergoing extratropical transition around Japan often present features that cannot be adequately simulated under these assumptions. These “left-hand-side contribution” (LHSC) wind fields exhibit strong winds on both sides of the moving cyclone with the maximum magnitude often located to the left. Classification of cyclones in terms of their most frequent patterns reveals that 67% of cases that make a transition around Japan are dominantly LHSC. They are more likely in autumn and have more intense maximum winds. The results from this study show the need for a new approach to the modeling of transitioning wind fields in the context of risk-assessment systems.
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Kravtsov, Sergey, and Christopher Spannagle. "Multidecadal Climate Variability in Observed and Modeled Surface Temperatures*." Journal of Climate 21, no. 5 (March 1, 2008): 1104–21. http://dx.doi.org/10.1175/2007jcli1874.1.
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Abstract This study identifies interdecadal natural climate variability in global surface temperatures by subtracting, from the observed temperature evolution, multimodel ensemble mean based on the World Climate Research Programme's (WCRP) Coupled Model Intercomparison Project phase 3 (CMIP3) multimodel dataset. The resulting signal resembles the so-called Atlantic multidecadal oscillation (AMO) and is presumably associated with intrinsic dynamics of the oceanic thermohaline circulation (THC). While certain phases of the oscillation are dominated by the anomalies in the North Atlantic region, other phases are characterized by global teleconnections to the North Pacific Ocean, tropical Atlantic Ocean, as well as the Southern Ocean. In particular, natural variability of sea surface temperature in the Atlantic hurricanes’ main development region has a peak-to-peak amplitude comparable in magnitude to this region’s surface temperature increase over the past century, for all seasons. Evidence suggests that the AMO influence on secular trends in the global-mean surface temperature can arise via direct, regional contribution to the surface temperature evolution, as well as via an indirect route linked to variability of the oceanic uptake of CO2 associated with AMO-related THC changes.
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Yang, S., X. Zou, and P. S. Ray. "Comparison of TC Temperature and Water Vapor Climatologies between the Atlantic and Pacific Oceans from GPS RO Observations." Journal of Climate 31, no. 20 (October 2018): 8557–71. http://dx.doi.org/10.1175/jcli-d-18-0074.1.
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Tropical cyclone (TC) temperature and water vapor structures are essential atmospheric variables. In this study, global positioning system (GPS) radio occultation (RO) observations from the GPS RO mission named the Constellation Observing System for Meteorology, Ionosphere, and Climate and the Global Navigation Satellite System (GNSS) Receiver for Atmospheric Sounding on board both MetOp-A and MetOp-B satellites over the 9-yr period from 2007 to 2015 are used to generate a set of composite structures of temperature and water vapor fields within tropical depressions (TDs), tropical storms (TSs), and hurricanes (HUs) over the Atlantic Ocean and TDs, TSs, and typhoons (TYs) over the western Pacific Ocean. The composite TC structures are different over the two oceanic regions, reflecting different climatological environments. The warm cores for TCs over the western Pacific Ocean have higher altitudes and larger sizes than do those over the Atlantic Ocean for all storm categories. A radial variation of the warm-core temperature anomaly with descending altitude is seen, probably resulting from spiral cloud and rainband features. The large TC water vapor pressure anomalies, which are often more difficult to obtain than temperature anomalies, are located below the maximum warm-core temperature anomaly centers. Thus, the maximum values of the fractional water vapor pressure anomaly, defined as the anomaly divided by the environmental value, for TSs and HUs over the Atlantic Ocean (1.4% for TSs and 2.2% for HUs) are higher than those for TSs and TYs over the western Pacific Ocean (1.2% for TSs and 1.4% for TYs). These TC structures are obtained only after a quality control procedure is implemented, which consists of a range check that removes negative refractivity values and unrealistic temperature values, as well as a biweight check that removes data that deviate from the biweight mean by more than 3 times the biweight standard deviation. A limitation of the present study is an inability to resolve the TC inner-core structures because of a lack of sufficient RO profiles that collocate with TCs in their inner-core regions and the relatively coarse along-track resolutions of GPS RO data.
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Benestad, R. E. "On tropical cyclone frequency and the warm pool area." Natural Hazards and Earth System Sciences 9, no. 2 (April 30, 2009): 635–45. http://dx.doi.org/10.5194/nhess-9-635-2009.
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Abstract. The proposition that the rate of tropical cyclogenesis increases with the size of the "warm pool" is tested by comparing the seasonal variation of the warm pool area with the seasonality of the number of tropical cyclones. An analysis based on empirical data from the Northern Hemisphere is presented, where the warm pool associated with tropical cyclone activity is defined as the area, A, enclosed by the 26.5°C SST isotherm. Similar analysis was applied to the temperature weighted area AT with similar results. An intriguing non-linear relationship of high statistical significance was found between the temperature weighted area in the North Atlantic and the North-West Pacific on the one hand and the number of cyclones, N, in the same ocean basin on the other, but this pattern was not found over the North Indian Ocean. A simple statistical model was developed, based on the historical relationship between N and A. The simple model was then validated against independent inter-annual variations in the seasonal cyclone counts in the North Atlantic, but the correlation was not statistically significant in the North-West Pacific. No correlation, however, was found between N and A in the North Indian Ocean. A non-linear relationship between the cyclone number and temperature weighted area may in some ocean basins explain both why there has not been any linear trend in the number of cyclones over time as well as the recent upturn in the number of Atlantic hurricanes. The results also suggest that the notion of the number of tropical cyclones being insensitive to the area A is a misconception.
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Zhao, Ming, Isaac M. Held, Shian-Jiann Lin, and Gabriel A. Vecchi. "Simulations of Global Hurricane Climatology, Interannual Variability, and Response to Global Warming Using a 50-km Resolution GCM." Journal of Climate 22, no. 24 (December 15, 2009): 6653–78. http://dx.doi.org/10.1175/2009jcli3049.1.
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Abstract A global atmospheric model with roughly 50-km horizontal grid spacing is used to simulate the interannual variability of tropical cyclones using observed sea surface temperatures (SSTs) as the lower boundary condition. The model’s convective parameterization is based on a closure for shallow convection, with much of the deep convection allowed to occur on resolved scales. Four realizations of the period 1981–2005 are generated. The correlation of yearly Atlantic hurricane counts with observations is greater than 0.8 when the model is averaged over the four realizations, supporting the view that the random part of this annual Atlantic hurricane frequency (the part not predictable given the SSTs) is relatively small (<2 hurricanes per year). Correlations with observations are lower in the east, west, and South Pacific (roughly 0.6, 0.5, and 0.3, respectively) and insignificant in the Indian Ocean. The model trends in Northern Hemisphere basin-wide frequency are consistent with the observed trends in the International Best Track Archive for Climate Stewardship (IBTrACS) database. The model generates an upward trend of hurricane frequency in the Atlantic and downward trends in the east and west Pacific over this time frame. The model produces a negative trend in the Southern Hemisphere that is larger than that in the IBTrACS. The same model is used to simulate the response to the SST anomalies generated by coupled models in the World Climate Research Program Coupled Model Intercomparison Project 3 (CMIP3) archive, using the late-twenty-first century in the A1B scenario. Results are presented for SST anomalies computed by averaging over 18 CMIP3 models and from individual realizations from 3 models. A modest reduction of global and Southern Hemisphere tropical cyclone frequency is obtained in each case, but the results in individual Northern Hemisphere basins differ among the models. The vertical shear in the Atlantic Main Development Region (MDR) and the difference between the MDR SST and the tropical mean SST are well correlated with the model’s Atlantic storm frequency, both for interannual variability and for the intermodel spread in global warming projections.
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Barrett, Bradford S., and Lance M. Leslie. "Links between Tropical Cyclone Activity and Madden–Julian Oscillation Phase in the North Atlantic and Northeast Pacific Basins." Monthly Weather Review 137, no. 2 (February 1, 2009): 727–44. http://dx.doi.org/10.1175/2008mwr2602.1.
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Abstract The leading intraseasonal mode of atmospheric and oceanic variability, the Madden–Julian oscillation (MJO), influences tropical and extratropical sea level pressure, temperature, divergent and rotational wind components, moisture, and deep convection. As a 40- to 50-day oscillation, the MJO is also known to influence tropical phenomena, including tropical cyclone (TC) activity in various TC basins. The links between the MJO and multiple measures of TC activity, including genesis, landfall, and an integrative accumulated cyclone energy (ACE) index, were quantified for multiple TC-formation basins across the Western Hemisphere, including the North Atlantic and northeast Pacific Ocean and subbasins, for the period 1978–2006. Using this relatively long (29 yr) TC dataset and employing an upper-tropospheric MJO diagnostic that is physically meaningful over the entire Western Hemisphere, this study extends existing research on the relationships between the MJO and TCs. The NOAA Climate Prediction Center’s operational MJO index, derived from 200-hPa velocity potential data, was divided into three phases. Relative frequencies of the MJO phases were compared with observed levels of TC activity using a binomial distribution hypothesis test. The MJO was found to statistically significantly modulate the frequency of TC genesis, intensification, and landfall in the nine TC basins studied. For example, when an MJO index was large and positive at 120°W, hurricanes and intense hurricanes were 4 times as likely to make landfall in the North Atlantic. This modulation of TC activity, including landfall patterns in the North Atlantic, was physically linked to the upper-atmospheric response to the eastward-propagating MJO and is evident as a dipole of TC activity between Pacific and Atlantic subbasins.
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Chen, Jan-Huey, and Shian-Jiann Lin. "Seasonal Predictions of Tropical Cyclones Using a 25-km-Resolution General Circulation Model." Journal of Climate 26, no. 2 (January 15, 2013): 380–98. http://dx.doi.org/10.1175/jcli-d-12-00061.1.
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Abstract Retrospective seasonal predictions of tropical cyclones (TCs) in the three major ocean basins of the Northern Hemisphere are performed from 1990 to 2010 using the Geophysical Fluid Dynamics Laboratory High-Resolution Atmospheric Model (HiRAM) at 25-km resolution. Atmospheric states are initialized for each forecast, with the sea surface temperature anomaly (SSTA) “persisted” from that at the starting time during the 5-month forecast period (July–November). Using a five-member ensemble, it is shown that the storm counts of both tropical storm (TS) and hurricane categories are highly predictable in the North Atlantic basin during the 21-yr period. The correlations between the 21-yr observed and model predicted storm counts are 0.88 and 0.89 for hurricanes and TSs, respectively. The prediction in the eastern North Pacific is skillful, but it is not as outstanding as that in the North Atlantic. The persistent SSTA assumption appears to be less robust for the western North Pacific, contributing to less skillful predictions in that region. The relative skill in the prediction of storm counts is shown to be consistent with the quality of the predicted large-scale environment in the three major basins. It is shown that intensity distribution of TCs can be captured well by the model if the central sea level pressure is used as the threshold variable instead of the commonly used 10-m wind speed. This demonstrates the feasibility of using the 25-km-resolution HiRAM, a general circulation model designed initially for long-term climate simulations, to study the impacts of climate change on the intensity distribution of TCs.
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Joshi, Drumil, Fawzan Sayed, Harsh Jain, Jai Beri, Yukti Bandi, and Dr Sunil Karamchandani. "A Cloud Native Machine Learning based Approach for Detection and Impact of Cyclone and Hurricanes on Coastal Areas of Pacific and Atlantic Ocean." Journal of University of Shanghai for Science and Technology 23, no. 07 (July 7, 2021): 394–99. http://dx.doi.org/10.51201/jusst/21/07149.
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Tropical Storms are one of the most dangerous natural disasters known to man. The concept of predicting these has been around for as long as they have existed. Improvements are made to reduce the error using newer techniques or better processes. In this research paper, we are trying to predict the occurrence of storms from the Pacific and the Atlantic Oceans on American land. The data is used to train various machine learning models and comparison is drawn between them to conclude the best for our application. The results are then shown on a map to get a visual representation using the folium library. The entire project is also deployed using Microsoft Machine Learning Azure to help with deployment over the web service. This paper hopes to present a system that accurately predicts and efficiently presents everything regarding the real-time occurrence of hurricanes and typhoons.
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McTaggart-Cowan, Ron, Lance F. Bosart, John R. Gyakum, and Eyad H. Atallah. "Hurricane Katrina (2005). Part II: Evolution and Hemispheric Impacts of a Diabatically Generated Warm Pool." Monthly Weather Review 135, no. 12 (December 1, 2007): 3927–49. http://dx.doi.org/10.1175/2007mwr2096.1.
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Abstract The landfall of Hurricane Katrina (2005) near New Orleans, Louisiana, on 29 August 2005 will be remembered as one of the worst natural disasters in the history of the United States. By comparison, the extratropical transition (ET) of the system as it accelerates poleward over the following days is innocuous and the system weakens until its eventual demise off the coast of Greenland. The extent of Katrina’s perturbation of the midlatitude flow would appear to be limited given the lack of reintensification or downstream development during ET. However, the slow progression of a strong upper-tropospheric warm pool across the North Atlantic Ocean in the week following Katrina’s landfall prompts the question of whether even a nonreintensifying ET event can lead to significant modification of the midlatitude flow. Analysis of Hurricane Katrina’s outflow layer after landfall suggests that it does not itself make up the long-lived midlatitude warm pool. However, the interaction between Katrina’s anticyclonic outflow and an approaching baroclinic trough is shown to establish an anomalous southwesterly conduit or “freeway” that injects a preexisting tropospheric warm pool over the southwestern United States into the midlatitudes. This warm pool reduces predictability in medium-range forecasts over the North Atlantic and Europe while simultaneously aiding in the development of Hurricanes Maria and Nate. The origin of the warm pool is shown to be the combination of anticyclonic upper-level features generated by eastern Pacific Hurricane Hilary and the south Asian anticyclone (SAA). The hemispheric nature of the connections involved with the development of the warm pool and its injection into the extratropics has an impact on forecasting, since the predictability issue associated with ET in this case involves far more than the potential reintensification of the transitioning system itself.
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Bell, Gerald D., Michael S. Halpert, Chester F. Ropelewski, Vernon E. Kousky, Arthur V. Douglas, Russell C. Schnell, and Melvyn E. Gelman. "Climate Assessment for 1998." Bulletin of the American Meteorological Society 80, no. 5s (May 1, 1999): S1—S48. http://dx.doi.org/10.1175/1520-0477-80.5s.s1.
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The global climate during 1998 was affected by opposite extremes of the ENSO cycle, with one of the strongest Pacific warm episodes (El Niño) in the historical record continuing during January–early May and Pacific cold episode (La Niña) conditions occurring from JulyñDecember. In both periods, regional temperature, rainfall, and atmospheric circulation patterns across the Pacific Ocean and the Americas were generally consistent with those observed during past warm and cold episodes. Some of the most dramatic impacts from both episodes were observed in the Tropics, where anomalous convection was evident across the entire tropical Pacific and in most major monsoon regions of the world. Over the Americas, many of the El Niño– (La Niña–) related rainfall anomalies in the subtropical and extratropical latitudes were linked to an extension (retraction) of the jet streams and their attendant circulation features typically located over the subtropical latitudes of both the North Pacific and South Pacific. The regions most affected by excessive El Niño–related rainfall included 1) the eastern half of the tropical Pacific, including western Ecuador and northwestern Peru, which experienced significant flooding and mudslides; 2) southeastern South America, where substantial flooding was also observed; and 3) California and much of the central and southern United States during January–March, and the central United States during April–June. El Niño–related rainfall deficits during 1998 included 1) Indonesia and portions of northern Australia; 2) the Amazon Basin, in association with a substantially weaker-than-normal South American monsoon circulation; 3) Mexico, which experienced extreme drought throughout the El Niño episode; and 4) the Gulf Coast states of the United States, which experienced extreme drought during April–June 1998. The El Niño also contributed to extreme warmth across North America during January–May. The primary La Niña–related precipitation anomalies included 1) increased rainfall across Indonesia, and a nearly complete disappearance of rainfall across the east-central equatorial Pacific; 2) above-normal rains across northwestern, eastern, and northern Australia; 3) increased monsoon rains across central America and Mexico during October–December; and 4) dryness across equatorial eastern Africa. The active 1998 North Atlantic hurricane season featured 14 named storms (9 of which became hurricanes) and the strongest October hurricane (Mitch) in the historical record. In Honduras and Nicaragua extreme flooding and mudslides associated with Hurricane Mitch claimed more than 11 000 lives. During the peak of activity in August–September, the vertical wind shear across the western Atlantic, along with both the structure and location of the African easterly jet, were typical of other active seasons. Other regional aspects of the short-term climate included 1) record rainfall and massive flooding in the Yangtze River Basin of central China during June–July; 2) a drier and shorter-than-normal 1997/98 rainy season in southern Africa; 3) above-normal rains across the northern section of the African Sahel during June–September 1998; and 4) a continuation of record warmth across Canada during June–November. Global annual mean surface temperatures during 1998 for land and marine areas were 0.56°C above the 1961–90 base period means. This record warmth surpasses the previous highest anomaly of +0.43°C set in 1997. Record warmth was also observed in the global Tropics and Northern Hemisphere extratropics during the year, and is partly linked to the strong El Nino conditions during January–early May.
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Mueller, Kimberly J., Mark DeMaria, John Knaff, James P. Kossin, and Thomas H. Vonder Haar. "Objective Estimation of Tropical Cyclone Wind Structure from Infrared Satellite Data." Weather and Forecasting 21, no. 6 (December 1, 2006): 990–1005. http://dx.doi.org/10.1175/waf955.1.
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Abstract Geostationary infrared (IR) satellite data are used to provide estimates of the symmetric and total low-level wind fields in tropical cyclones, constructed from estimations of an azimuthally averaged radius of maximum wind (RMAX), a symmetric tangential wind speed at a radius of 182 km (V182), a storm motion vector, and the maximum intensity (VMAX). The algorithm is derived using geostationary IR data from 405 cases from 87 tropical systems in the Atlantic and east Pacific Ocean basins during the 1995–2003 hurricane seasons that had corresponding aircraft data available. The algorithm is tested on 50 cases from seven tropical storms and hurricanes during the 2004 season. Aircraft-reconnaissance-measured RMAX and V182 are used as dependent variables in a multiple linear regression technique, and VMAX and the storm motion vector are estimated using conventional methods. Estimates of RMAX and V182 exhibit mean absolute errors (MAEs) of 27.3 km and 6.5 kt, respectively, for the dependent samples. A modified combined Rankine vortex model is used to estimate the one-dimensional symmetric tangential wind field from VMAX, RMAX, and V182. Next, the storm motion vector is added to the symmetric wind to produce estimates of the total wind field. The MAE of the IR total wind retrievals is 10.4 kt, and the variance explained is 53%, when compared with the two-dimensional wind fields from the aircraft data for the independent cases.
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Sutton, Rowan T., and Daniel L. R. Hodson. "Climate Response to Basin-Scale Warming and Cooling of the North Atlantic Ocean." Journal of Climate 20, no. 5 (March 1, 2007): 891–907. http://dx.doi.org/10.1175/jcli4038.1.
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Abstract Using experiments with an atmospheric general circulation model, the climate impacts of a basin-scale warming or cooling of the North Atlantic Ocean are investigated. Multidecadal fluctuations with this pattern were observed during the twentieth century, and similar variations—but with larger amplitude—are believed to have occurred in the more distant past. It is found that in all seasons the response to warming the North Atlantic is strongest, in the sense of highest signal-to-noise ratio, in the Tropics. However there is a large seasonal cycle in the climate impacts. The strongest response is found in boreal summer and is associated with suppressed precipitation and elevated temperatures over the lower-latitude parts of North and South America. In August–September–October there is a significant reduction in the vertical shear in the main development region for Atlantic hurricanes. In winter and spring, temperature anomalies over land in the extratropics are governed by dynamical changes in circulation rather than simply reflecting a thermodynamic response to the warming or cooling of the ocean. The tropical climate response is primarily forced by the tropical SST anomalies, and the major features are in line with simple models of the tropical circulation response to diabatic heating anomalies. The extratropical climate response is influenced both by tropical and higher-latitude SST anomalies and exhibits nonlinear sensitivity to the sign of the SST forcing. Comparisons with multidecadal changes in sea level pressure observed in the twentieth century support the conclusion that the impact of North Atlantic SST change is most important in summer, but also suggest a significant influence in lower latitudes in autumn and winter. Significant climate impacts are not restricted to the Atlantic basin, implying that the Atlantic Ocean could be an important driver of global decadal variability. The strongest remote impacts are found to occur in the tropical Pacific region in June–August and September–November. Surface anomalies in this region have the potential to excite coupled ocean–atmosphere feedbacks, which are likely to play an important role in shaping the ultimate climate response.
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Mei, Wei, Shang-Ping Xie, and Ming Zhao. "Variability of Tropical Cyclone Track Density in the North Atlantic: Observations and High-Resolution Simulations." Journal of Climate 27, no. 13 (July 2014): 4797–814. http://dx.doi.org/10.1175/jcli-d-13-00587.1.
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Interannual–decadal variability of tropical cyclone (TC) track density over the North Atlantic (NA) between 1979 and 2008 is studied using observations and simulations with a 25-km-resolution version of the High Resolution Atmospheric Model (HiRAM) forced by observed sea surface temperatures (SSTs). The variability on decadal and interannual time scales is examined separately. On both time scales, a basinwide mode dominates, with the time series being related to variations in seasonal TC counts. On decadal time scales, this mode relates to SST contrasts between the tropical NA and the tropical northeast Pacific as well as the tropical South Atlantic, whereas on interannual time scales it is controlled by SSTs over the central–eastern equatorial Pacific and those over the tropical NA. The temporal evolution of the spatial distribution of track density is further investigated by normalizing the track density with seasonal TC counts. On decadal time scales, two modes emerge: one is an oscillation between track density over the U.S. East Coast and midlatitude ocean and that over the Gulf of Mexico and the Caribbean Sea and the other oscillates between low and middle latitudes. They might be driven by the preceding winter North Atlantic Oscillation and concurrent Atlantic meridional mode, respectively. On interannual time scales, two similar modes are present in observations but are not well separated in HiRAM simulations. Finally, the internal variability and predictability of TC track density are explored and discussed using HiRAM ensemble simulations. The results suggest that basinwide total TC counts/days are much more predictable than local TC occurrence, posing a serious challenge to the prediction and projection of regional TC threats, especially the U.S. landfall hurricanes.
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Capra, Lucia, Velio Coviello, Lorenzo Borselli, Víctor-Hugo Márquez-Ramírez, and Raul Arámbula-Mendoza. "Hydrological control of large hurricane-induced lahars: evidence from rainfall-runoff modeling, seismic and video monitoring." Natural Hazards and Earth System Sciences 18, no. 3 (March 9, 2018): 781–94. http://dx.doi.org/10.5194/nhess-18-781-2018.
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Abstract. The Volcán de Colima, one of the most active volcanoes in Mexico, is commonly affected by tropical rains related to hurricanes that form over the Pacific Ocean. In 2011, 2013 and 2015 hurricanes Jova, Manuel and Patricia, respectively, triggered tropical storms that deposited up to 400 mm of rain in 36 h, with maximum intensities of 50 mm h −1. The effects were devastating, with the formation of multiple lahars along La Lumbre and Montegrande ravines, which are the most active channels in sediment delivery on the south-southwest flank of the volcano. Deep erosion along the river channels and several marginal landslides were observed, and the arrival of block-rich flow fronts resulted in damages to bridges and paved roads in the distal reaches of the ravines. The temporal sequence of these flow events is reconstructed and analyzed using monitoring data (including video images, seismic records and rainfall data) with respect to the rainfall characteristics and the hydrologic response of the watersheds based on rainfall-runoff numerical simulation. For the studied events, lahars occurred 5–6 h after the onset of rainfall, lasted several hours and were characterized by several pulses with block-rich fronts and a maximum flow discharge of 900 m3 s −1. Rainfall-runoff simulations were performer using the SCS-curve number and the Green–Ampt infiltration models, providing a similar result in the detection of simulated maximum watershed peaks discharge. Results show different behavior for the arrival times of the first lahar pulses that correlate with the simulated catchment's peak discharge for La Lumbre ravine and with the peaks in rainfall intensity for Montegrande ravine. This different behavior is related to the area and shape of the two watersheds. Nevertheless, in all analyzed cases, the largest lahar pulse always corresponds with the last one and correlates with the simulated maximum peak discharge of these catchments. Data presented here show that flow pulses within a lahar are not randomly distributed in time, and they can be correlated with rainfall peak intensity and/or watershed discharge, depending on the watershed area and shape. This outcome has important implications for hazard assessment during extreme hydro-meteorological events, as it could help in providing real-time alerts. A theoretical rainfall distribution curve was designed for Volcán de Colima based on the rainfall and time distribution of hurricanes Manuel and Patricia. This can be used to run simulations using weather forecasts prior to the actual event, in order to estimate the arrival time of main lahar pulses, usually characterized by block-rich fronts, which are responsible for most of the damage to infrastructure and loss of goods and lives.
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Kupriyanov, A. "“Soft Power” of the Indian Navy in the Pandemic Era." Analysis and Forecasting. IMEMO Journal, no. 4 (2020): 40–51. http://dx.doi.org/10.20542/afij-2020-4-40-51.
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The article describes and analyzes the activities of the Indian Navy during the COVID-19 pandemic. The author looks at the experience of the Indian Navy at the beginning of the pandemic, noting that it mainly consisted of helping the states of the Indian Ocean region affected by hurricanes and monsoons, and evacuating Indian citizens and residents of neighboring countries from areas of hostilities. At the same time, the Indian Navy did not have specialized floating hospitals. The author analyzes the situation in which India found itself at the beginning of the pandemic: a gradual slowdown in GDP growth questioned the further expansion of the Navy, and the outbreak of conflict with China further emphasized the importance of the Air Force and the Army. In these conditions, the Indian Navy was forced to prove its value for the Indian external and domestic policy. The author then describes how the Indian Navy fought COVID-19, concluding that Indian sailors were able to prevent the pandemic from spreading to naval bases and ships. The Navy fully retained its combat capability and was able to take part in two large-scale operations: the “Samudra Setu”and “Sagar” missions. During the former, several thousand people were evacuated from Iran, Sri Lanka and the Maldives, the latter involved providing medical assistance to the population of the Maldives, Seychelles, Comoros, Madagascar and Mauritius affected by the pandemic. The author notes the high level of organization of both missions, which made it possible to avoid pandemic spreading among the ship crews. He argues that the conduct of Operation “Sagar” allowed India to increase its influence in the Indian Ocean region amid the pandemic and demonstrate its role as a security provider countering unconventional threats. The author then describes the joint exercises carried out by the Indian Navy during the pandemic and notes their significant political role. In conclusion, he analyzes the experience of the Indian Navy using soft power and proposes an original concept of “floating soft power” based on the constant presence of hospital ships in remote regions. In his opinion, this format of presence could also be suitable for projecting Russian interests in the South Pacific.
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Shay, Lynn K., and Jodi K. Brewster. "Oceanic Heat Content Variability in the Eastern Pacific Ocean for Hurricane Intensity Forecasting." Monthly Weather Review 138, no. 6 (June 1, 2010): 2110–31. http://dx.doi.org/10.1175/2010mwr3189.1.
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Abstract Recent evidence supports the premise that the subsurface ocean structure plays an important role in modulating air–sea fluxes during hurricane passage, which in turn, affects intensity change. Given the generally sparse in situ data, it has been difficult to provide region-to-basin-wide estimates of isotherm depths and upper-ocean heat content (OHC). In this broader context, satellite-derived sea surface height anomalies (SSHAs) from multiple platforms carrying radar altimeters are blended, objectively analyzed, and combined with a hurricane-season climatology to estimate isotherm depths and OHC within the context of a reduced gravity model at 0.25° spatial intervals in the eastern Pacific Ocean where tropical cyclone intensity change occurs. Measurements from the Eastern Pacific Investigation of Climate in 2001, long-term tropical ocean atmosphere mooring network, and volunteer observing ship deploying expendable bathythermograph (XBT) profilers are used to carefully evaluate satellite-based measurements of upper-ocean variability. Regression statistics reveal small biases with slopes of 0.8–0.9 between the subsurface measurements compared with isotherm depths (20° and 26°C), and OHC fields derived from objectively analyzed SSHA field. Root-mean-square differences in OHC range between 10 and 15 kJ cm−2 or roughly 10%–15% of the mean signals. Similar values are found for isotherm depth differences between in situ and inferred satellite-derived values. Blended daily values are used in the Statistical Hurricane Intensity Prediction Scheme (SHIPS) forecasts as are OHC estimates for the Atlantic Ocean basin. An equivalent OHC variable is introduced that incorporates the strength of the thermocline at the base of the oceanic mixed layer using a climatological stratification parameter /No, which seems better correlated to hurricane intensity change than just anomalies as observed in Hurricane Juliette in 2001.
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Boucharel, Julien, Fei-Fei Jin, Matthew H. England, Boris Dewitte, I. I. Lin, Hsiao-Ching Huang, and Magdalena A. Balmaseda. "Influence of Oceanic Intraseasonal Kelvin Waves on Eastern Pacific Hurricane Activity." Journal of Climate 29, no. 22 (October 21, 2016): 7941–55. http://dx.doi.org/10.1175/jcli-d-16-0112.1.
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Abstract Recent studies have highlighted the role of subsurface ocean dynamics in modulating eastern Pacific (EPac) hurricane activity on interannual time scales. In particular, the well-known El Niño–Southern Oscillation (ENSO) recharge–discharge mechanism has been suggested to provide a good understanding of the year-to-year variability of hurricane activity in this region. This paper investigates the influence of equatorial subsurface subannual and intraseasonal oceanic variability on tropical cyclone (TC) activity in the EPac. That is to say, it examines previously unexplored time scales, shorter than interannual, in an attempt to explain the variability not related to ENSO. Using ocean reanalysis products and TC best-track archive, the role of subannual and intraseasonal equatorial Kelvin waves (EKW) in modulating hurricane intensity in the EPac is examined. It is shown first that these planetary waves have a clear control on the subannual and intraseasonal variability of thermocline depth in the EPac cyclone-active region. This is found to affect ocean subsurface temperature, which in turn fuels hurricane intensification with a marked seasonal-phase locking. This mechanism of TC fueling, which explains up to 30% of the variability of TC activity unrelated to ENSO (around 15%–20% of the total variability), is embedded in the large-scale equatorial dynamics and therefore offers some predictability with lead time up to 3–4 months at seasonal and subseasonal time scales.
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Lin, I.-I., Chun-Chieh Wu, Kerry A. Emanuel, I.-Huan Lee, Chau-Ron Wu, and Iam-Fei Pun. "The Interaction of Supertyphoon Maemi (2003) with a Warm Ocean Eddy." Monthly Weather Review 133, no. 9 (September 1, 2005): 2635–49. http://dx.doi.org/10.1175/mwr3005.1.
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Abstract Understanding the interaction of ocean eddies with tropical cyclones is critical for improving the understanding and prediction of the tropical cyclone intensity change. Here an investigation is presented of the interaction between Supertyphoon Maemi, the most intense tropical cyclone in 2003, and a warm ocean eddy in the western North Pacific. In September 2003, Maemi passed directly over a prominent (700 km × 500 km) warm ocean eddy when passing over the 22°N eddy-rich zone in the northwest Pacific Ocean. Analyses of satellite altimetry and the best-track data from the Joint Typhoon Warning Center show that during the 36 h of the Maemi–eddy encounter, Maemi’s intensity (in 1-min sustained wind) shot up from 41 m s−1 to its peak of 77 m s−1. Maemi subsequently devastated the southern Korean peninsula. Based on results from the Coupled Hurricane Intensity Prediction System and satellite microwave sea surface temperature observations, it is suggested that the warm eddies act as an effective insulator between typhoons and the deeper ocean cold water. The typhoon’s self-induced sea surface temperature cooling is suppressed owing to the presence of the thicker upper-ocean mixed layer in the warm eddy, which prevents the deeper cold water from being entrained into the upper-ocean mixed layer. As simulated using the Coupled Hurricane Intensity Prediction System, the incorporation of the eddy information yields an evident improvement on Maemi’s intensity evolution, with its peak intensity increased by one category and maintained at category-5 strength for a longer period (36 h) of time. Without the presence of the warm ocean eddy, the intensification is less rapid. This study can serve as a starting point in the largely speculative and unexplored field of typhoon–warm ocean eddy interaction in the western North Pacific. Given the abundance of ocean eddies and intense typhoons in the western North Pacific, these results highlight the importance of a systematic and in-depth investigation of the interaction between typhoons and western North Pacific eddies.
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Zhao, Ming, Isaac M. Held, and Gabriel A. Vecchi. "Retrospective Forecasts of the Hurricane Season Using a Global Atmospheric Model Assuming Persistence of SST Anomalies." Monthly Weather Review 138, no. 10 (October 1, 2010): 3858–68. http://dx.doi.org/10.1175/2010mwr3366.1.
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Abstract Retrospective predictions of seasonal hurricane activity in the Atlantic and east Pacific are generated using an atmospheric model with 50-km horizontal resolution by simply persisting sea surface temperature (SST) anomalies from June through the hurricane season. Using an ensemble of 5 realizations for each year between 1982 and 2008, the correlations of the model mean predictions with observations of basin-wide hurricane frequency are 0.69 in the North Atlantic and 0.58 in the east Pacific. In the North Atlantic, a significant part of the degradation in skill as compared to a model forced with observed SSTs during the hurricane season (correlation of 0.78) can be explained by the change from June through the hurricane season in one parameter, the difference between the SST in the main development region and the tropical mean SST. In fact, simple linear regression models with this one predictor perform nearly as well as the full dynamical model for basin-wide hurricane frequency in both the east Pacific and the North Atlantic. The implication is that the quality of seasonal forecasts based on a coupled atmosphere–ocean model will depend in large part on the model’s ability to predict the evolution of this difference between main development region SST and tropical mean SST.
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Businger, Steven, Selen Yildiz, and Thomas E. Robinson. "The Impact of Hurricane Force Wind Fields on the North Pacific Ocean Environment." Weather and Forecasting 30, no. 3 (June 1, 2015): 742–53. http://dx.doi.org/10.1175/waf-d-14-00107.1.
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AbstractThis study analyzes QuikSCAT surface wind data over the North Pacific Ocean to document the distribution of captured fetches in extratropical cyclones that produced hurricane force (HF) wind fields from January 2003 through May 2008. A case study is presented to introduce the datasets, which include surface wind analyses from the Global Forecast System (GFS) Global Data Assimilation System (GDAS), and wave hindcasts from the third-generation wave model (WAVEWATCH III; hereafter, WW3), in addition to the QuikSCAT surface wind data. The analysis shows significant interannual variability in the location of the captured fetches as documented by QuikSCAT, including a shift in the distribution of captured fetches associated with ENSO. GDAS surface winds over the ocean are consistently underanalyzed when compared to QuikSCAT surface winds, despite the fact that satellite observations of ocean surface winds are assimilated. When the WW3 hindcasts associated with HF cyclones are compared with buoy observations over the eastern and central North Pacific Ocean, the wave model significantly underestimates the large-swell events.
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Von Ahn, Joan M., Joseph M. Sienkiewicz, and Paul S. Chang. "Operational Impact of QuikSCAT Winds at the NOAA Ocean Prediction Center." Weather and Forecasting 21, no. 4 (August 1, 2006): 523–39. http://dx.doi.org/10.1175/waf934.1.
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Abstract The NASA Quick Scatterometer (QuikSCAT) has revolutionized the analysis and short-term forecasting of winds over the oceans at the NOAA Ocean Prediction Center (OPC). The success of QuikSCAT in OPC operations is due to the wide 1800-km swath width, large retrievable wind speed range (0 to in excess of 30 m s−1), ability to view QuikSCAT winds in a comprehensive form in operational workstations, and reliable near-real-time delivery of data. Prior to QuikSCAT, marine forecasters at the OPC made warning and forecast decisions over vast ocean areas based on a limited number of conventional observations or on the satellite presentation of a storm system. Today, QuikSCAT winds are a heavily used tool by OPC forecasters. Approximately 10% of all short-term wind warning decisions by the OPC are based on QuikSCAT winds. When QuikSCAT is available, 50%–68% of all weather features on OPC surface analyses are placed using QuikSCAT. QuikSCAT is the first remote sensing instrument that can consistently distinguish extreme hurricane force conditions from less dangerous storm force conditions in extratropical cyclones. During each winter season (October–April) from 2001 to 2004, 15–23 extratropical cyclones reached hurricane force intensity over both the North Atlantic and North Pacific Oceans. Due to QuikSCAT, OPC forecasters are now more likely to anticipate the onset of hurricane force conditions. QuikSCAT has also revealed significant wind speed gradients in the vicinity of strong sea surface temperature (SST) differences near the Gulf Stream and shelfbreak front of the western North Atlantic. These wind speed gradients are most likely due to changes in low-level stability of the boundary layer across the SST gradients. OPC forecasters now use a variety of numerical guidance based tools to help predict boundary layer stability and the resultant near-surface winds.
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Farfán, Luis M., and Ira Fogel. "Influence of Tropical Cyclones on Humidity Patterns over Southern Baja California, Mexico." Monthly Weather Review 135, no. 4 (April 1, 2007): 1208–24. http://dx.doi.org/10.1175/mwr3356.1.
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Abstract The influence of tropical cyclone circulations in the distribution of humidity and convection over northwestern Mexico is investigated by analyzing circulations that developed in the eastern Pacific Ocean from 1 July to 21 September 2004. Documented cases having some impact over the Baja California Peninsula include Tropical Storm Blas (13–15 July), Hurricane Frank (23–25 August), Hurricane Howard (2–6 September), and Hurricane Javier (15–20 September). Datasets are derived from geostationary satellite imagery, upper-air and surface station observations, as well as an analysis from an operational model. Emphasis is given to circulations that moved within 800 km of the southern part of the peninsula. The distribution of precipitable water is used to identify distinct peaks during the approach of these circulations and deep convection that occurred for periods of several days over the southern peninsula and Gulf of California. Hurricane Howard is associated with a significant amount of precipitation, while Hurricane Javier made landfall across the central peninsula with a limited impact on the population in the area. An examination of the large-scale environment suggests that advection of humid air from the equatorial Pacific is an important element in sustaining tropical cyclones and convection off the coast of western Mexico.
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Mignucci-Giannoni, Antonio A., Gian M. Toyos-González, Janice Pérez-Padilla, Marta A. Rodríguez-López, and Julie Overing. "Mass stranding of pygmy killer whales (Feresa attenuata) in the British Virgin Islands." Journal of the Marine Biological Association of the United Kingdom 80, no. 2 (April 2000): 383–84. http://dx.doi.org/10.1017/s0025315499002076.
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The pygmy killer whale (Feresa attenuata) is an offshore, tropical and subtropical delphinid found in the Atlantic, Indian and Pacific Oceans. The species has only recently been studied, mostly from specimens collected from strandings. While over 52 reports exist for the Atlantic Ocean, only one record exists for the Caribbean Sea. A new record of a mass stranding of pygmy killer whales from the British Virgin Islands is documented and the pathology and life history of the specimens is described, associating the stranding process with the meteorological and oceanographic disturbance of Hurricane Marilyn, which devastated the Virgin Islands a day prior to the stranding. This stranding event constitutes the sixth known mass stranding for the species worldwide, the first record for pygmy killer whales for the northeastern Caribbean and the second for the entire Caribbean Sea.
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Mignucci-Giannoni, Antonio A., Gian M. Toyos-González, Janice Pérez-Padilla, Marta A. Rodríguez-López, and Julie Overing. "Mass stranding of pygmy killer whales (Feresa attenuata) in the British Virgin Islands." Journal of the Marine Biological Association of the United Kingdom 80, no. 4 (August 2000): 759–60. http://dx.doi.org/10.1017/s0025315499002702.
Full textAbstract:
The pygmy killer whale (Feresa attenuata) is an offshore, tropical and subtropical delphinid found in the Atlantic, Indian and Pacific Oceans. The species has only recently been studied, mostly from specimens collected from strandings. While over 52 reports exist for the Atlantic Ocean, only one record exists for the Caribbean Sea. A new record of a mass stranding of pygmy killer whales from the British Virgin Islands is documented and the pathology and life history of the specimens is described, associating the stranding process with the meteorological and oceanographic disturbance of Hurricane Marilyn, which devastated the Virgin Islands a day prior to the stranding. This stranding event constitutes the sixth known mass stranding for the species worldwide, the first record for pygmy killer whales for the northeastern Caribbean and the second for the entire Caribbean Sea.
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Hall, Timothy, and Michael K. Tippett. "Pacific Hurricane Landfalls on Mexico and SST." Journal of Applied Meteorology and Climatology 56, no. 3 (March 2017): 667–76. http://dx.doi.org/10.1175/jamc-d-16-0194.1.
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AbstractA statistical model of northeastern Pacific Ocean tropical cyclones (TCs) is developed and used to estimate hurricane landfall rates along the coast of Mexico. Mean annual landfall rates for 1971–2014 are compared with mean rates for the extremely high northeastern Pacific sea surface temperature (SST) of 2015. Over the full coast, the mean rate and 5%–95% uncertainty range (in parentheses) for TCs that are category 1 and higher on the Saffir–Simpson scale (C1+ TCs) are 1.24 (1.05, 1.33) yr−1 for 1971–2014 and 1.69 (0.89, 2.08) yr−1 for 2015—a difference that is not significant. The increase for the most intense landfalls (category-5 TCs) is significant: 0.009 (0.006, 0.011) yr−1 for 1971–2014 and 0.031 (0.016, 0.036) yr−1 for 2015. The SST impact on the rate of category-5 TC landfalls is largest on the northern Mexican coast. The increased landfall rates for category-5 TCs are consistent with independent analysis showing that SST has its greatest impact on the formation rates of the most intense northeastern Pacific TCs. Landfall rates on Hawaii [0.033 (0.019, 0.045) yr−1 for C1+ TCs and 0.010 (0.005, 0.016) yr−1 for C3+ TCs for 1971–2014] show increases in the best estimates for 2015 conditions, but the changes are statistically insignificant.
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Chu, Kekuan, and Zhe-Min Tan. "Annular Typhoons in the Western North Pacific." Weather and Forecasting 29, no. 2 (April 1, 2014): 241–51. http://dx.doi.org/10.1175/waf-d-13-00060.1.
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Abstract Annular hurricanes, characterized by annular structure, are a subset of mature-stage intense tropical cyclones, and they tend to be stronger and persist longer than average tropical cyclones. The characteristics of annular hurricanes in the North Atlantic and eastern-central North Pacific Oceans are well documented by Knaff et al. However, little is known about the annular typhoons in the western North Pacific (WNP). This study investigates the general features of annular typhoons in the WNP based on a 20-yr analysis (1990–2009) of global storm-centered infrared brightness temperature and passive microwave satellite datasets. Similar to annular hurricanes, annular typhoons also only form under a specific combination of environmental conditions, resulting in a quite low occurrence rate (~4%), and only 12 annular typhoons occur during this period. The concentric eyewall replacement is one effective pathway to annular typhoon formation. Three annular typhoons experienced the concentric eyewall replacement within 24 h prior to their annular phases during this period. There are two seedbeds, located east of Taiwan and in the central WNP, for annular typhoon formation within a narrow zonal belt (20°–30°N). The former is conducive to the landfall of annular typhoons, in particular six of the nine annular typhoons that formed in this region eventually made landfall. Because the average time interval between landfall of the annular typhoons and the end of their annular phase is relatively short, about 30 h, they can maintain near-peak intensities and hit the landfalling areas with record intensities. They present a unique threat to eastern Asia but have received little attention from the scientific community so far.
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Merritt-Takeuchi, Ashley M., and Sen Chiao. "Case Studies of Tropical Cyclones and Phytoplankton Blooms over Atlantic and Pacific Regions." Earth Interactions 17, no. 17 (September 1, 2013): 1–19. http://dx.doi.org/10.1175/2013ei000517.1.
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Abstract This study investigates phytoplankton blooms following the passage of tropical cyclones in the Atlantic and Pacific Ocean basins. The variables of sea surface temperature (SST), chlorophyll (Chl-a), precipitation, and storm surface winds were monitored for two case studies, Typhoon Xangsane (2006) and Hurricane Earl (2010). Strong near-surface wind from tropical cyclones creates internal friction, which causes deep nutrient enriched waters to displace from the bottom of the ocean floor up toward the surface. In return, the abundance of upwelled nutrients near the surface provides an ideal environment for the growth of biological substances such as chlorophyll and phytoplankton. The inverse correlation coefficients of SST and Chl-a for this study are −0.67 and −0.26 for Xangsane and Earl, respectively. This suggests that, regardless of ocean basin, changing sea surface temperature and chlorophyll concentrations can be correlated to various characteristics of tropical cyclones including precipitation and surface wind, which in combination results in an increase of phytoplankton.
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Trabing, Benjamin C., and Michael M. Bell. "Understanding Error Distributions of Hurricane Intensity Forecasts during Rapid Intensity Changes." Weather and Forecasting 35, no. 6 (December 2020): 2219–34. http://dx.doi.org/10.1175/waf-d-19-0253.1.
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AbstractThe characteristics of official National Hurricane Center (NHC) intensity forecast errors are examined for the North Atlantic and east Pacific basins from 1989 to 2018. It is shown how rapid intensification (RI) and rapid weakening (RW) influence yearly NHC forecast errors for forecasts between 12 and 48 h in length. In addition to being the tail of the intensity change distribution, RI and RW are at the tails of the forecast error distribution. Yearly mean absolute forecast errors are positively correlated with the yearly number of RI/RW occurrences and explain roughly 20% of the variance in the Atlantic and 30% in the east Pacific. The higher occurrence of RI events in the east Pacific contributes to larger intensity forecast errors overall but also a better probability of detection and success ratio. Statistically significant improvements to 24-h RI forecast biases have been made in the east Pacific and to 24-h RW biases in the Atlantic. Over-ocean 24-h RW events cause larger mean errors in the east Pacific that have not improved with time. Environmental predictors from the Statistical Hurricane Intensity Prediction Scheme (SHIPS) are used to diagnose what conditions lead to the largest RI and RW forecast errors on average. The forecast error distributions widen for both RI and RW when tropical systems experience low vertical wind shear, warm sea surface temperature, and moderate low-level relative humidity. Consistent with existing literature, the forecast error distributions suggest that improvements to our observational capabilities, understanding, and prediction of inner-core processes is paramount to both RI and RW prediction.