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Lindgren, Ville, Tero Niemi, Harri Koivusalo, and Teemu Kokkonen. "Value of Spatially Distributed Rainfall Design Events—Creating Basin-Scale Stochastic Design Storm Ensembles." Water 15, no. 17 (2023): 3066. http://dx.doi.org/10.3390/w15173066.
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Current design storms used in hydrological modeling, urban planning, and dimensioning of structures are typically point-scale rainfall events with a steady rainfall intensity or a simple temporal intensity pattern. This can lead to oversimplified results because real rainfall events have more complex patterns than simple design series. In addition, the interest of hydrologists is usually in areal estimates rather than point values, most commonly in river-basin-wide areal mean rainfall estimates. By utilizing weather radar data and the short-term ensemble prediction system pySTEPS, which has so far been used for precipitation nowcasting, ensembles of high-resolution stochastic design storms with desired statistical properties and spatial structure evolving in time are generated. pySTEPS is complemented by adding time-series models for areal average rainfall over the simulation domain and field advection vectors. The selected study area is the Kokemäenjoki river basin located in Western Finland, and the model parametrization is carried out utilizing the Finnish Meteorological Institute’s weather radar data from the years 2013 to 2016. The results demonstrate how simulated events with similar large-scale mean areal rainfall can produce drastically different total event rainfalls in smaller scales. The sampling method, areal vs. gauge estimate, is also shown to have a prominent effect on total event rainfall across different spatial scales. The outlined method paves the way towards a more thorough and wide-spread assessment of the hydrological impacts of spatiotemporal rainfall characteristics.
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Kim, Youngkyu, Minwoo Son, and Sunmin Kim. "Application of Large-scale Climate Simulation Data to Evaluate the Scale of Extreme Rainfall Events: A Case of the 2018 Hiroshima Extreme-scale Rainfall Event." Journal of the Korean Society of Hazard Mitigation 22, no. 2 (2022): 27–38. http://dx.doi.org/10.9798/kosham.2022.22.2.27.
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This study aims to apply large-scale climate ensemble simulation data to evaluate the magnitude of extreme rainfall events. It was conducted on the basis of extreme rainfall that occurred in the Hiroshima region in 2018. This event recorded an extreme rainfall magnitude corresponding to a return period of 1,000 years at a 24-h rainfall duration; it is difficult to evaluate this magnitude with the concept of probability rainfall based on frequency analysis due to the short observation period. To overcome this limitation, the data for policy decision making for future (d4PDF) climate change database based on a large-scale climate ensemble simulation was used. These data provided 3,000 annual maximum daily rainfall values, which were used to empirically estimate the probability rainfall with a return period of 10-1,000 years based on a non-parametric approach without statistical methods. The estimated probability rainfall of the d4PDF was compared with the estimated probability obtained from the observed rainfall and frequency analysis. The difference between the two probability rainfall values was 3.53% for the return period of 50 years. However, as the return period increases, the error increases to more than 10%. This indicates that the estimation of the probability rainfall with a long-term return period using the observed data of a relatively short period may present uncertainties. Regarding the probability rainfall using d4PDF under present climate conditions, the Hiroshima event represented a return period of nearly 300 years. Meanwhile, for the probability rainfall using the d4PDF under future climate conditions, the Hiroshima event had a return period of nearly 100 years. Consequently, the magnitude of the probability rainfall increased in future climate conditions, and the probability of the occurrence of extreme rainfall corresponding to the Hiroshima event increased from 0.33% to 1%. Therefore, d4PDF can be used to quantitatively evaluate the magnitude of extreme rainfall events under present and future climate conditions.
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Carbone, Marco, Michele Turco, Giuseppe Brunetti, and Patrizia Piro. "Minimum Inter-Event Time to Identify Independent Rainfall Events in Urban Catchment Scale." Advanced Materials Research 1073-1076 (December 2014): 1630–33. http://dx.doi.org/10.4028/www.scientific.net/amr.1073-1076.1630.
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For many hydrologic analyses, planning or design problems, reliable rainfall estimates are necessary. For this reason, an accurate estimation of storm event properties is central to continuous simulation of rainfall. Rainfall is generally noted as single events or storms where the beginning and the end are defined by rainless of particular size duration called Minimum Inter-event Time (MIT). Starting from a critical study of the state of the art, this paper intends to investigate the definition of MIT for rainfall events shorter than an hour that, on an urban scale, are the most critical for designers, planners and operators of urban drainage system. All event characteristics such as depth and mean rain rate, are influenced by the choice of the value of MIT. This paper reviews the range of approaches used in literature and after this, based on a year of pluviograph records on an urban catchment, proposes a value of MIT according to catchment network entry time.
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Rebora, N., L. Ferraris, J. von Hardenberg, and A. Provenzale. "Rainfall downscaling and flood forecasting: a case study in the Mediterranean area." Natural Hazards and Earth System Sciences 6, no. 4 (2006): 611–19. http://dx.doi.org/10.5194/nhess-6-611-2006.
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Abstract. The prediction of the small-scale spatial-temporal pattern of intense rainfall events is crucial for flood risk assessment in small catchments and urban areas. In the absence of a full deterministic modelling of small-scale rainfall, it is common practice to resort to the use of stochastic downscaling models to generate ensemble rainfall predictions to be used as inputs to rainfall-runoff models. In this work we present an application of a new spatial-temporal downscaling procedure, called RainFARM, to an intense precipitation event predicted by the limited-area meteorological model Lokal Model over north-west Italy. The uncertainty in flood prediction associated with the small unresolved scales of forecasted precipitation fields is evaluated by using an ensemble of downscaled fields to drive a semi-distributed rainfall-runoff model.
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Rebora, Nicola, Luca Ferraris, Jost von Hardenberg, and Antonello Provenzale. "RainFARM: Rainfall Downscaling by a Filtered Autoregressive Model." Journal of Hydrometeorology 7, no. 4 (2006): 724–38. http://dx.doi.org/10.1175/jhm517.1.
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Abstract A method is introduced for stochastic rainfall downscaling that can be easily applied to the precipitation forecasts provided by meteorological models. Our approach, called the Rainfall Filtered Autoregressive Model (RainFARM), is based on the nonlinear transformation of a Gaussian random field, and it conserves the information present in the rainfall fields at larger scales. The procedure is tested on two radar-measured intense rainfall events, one at midlatitude and the other in the Tropics, and it is shown that the synthetic fields generated by RainFARM have small-scale statistical properties that are consistent with those of the measured precipitation fields. The application of the disaggregation procedure to an example meteorological forecast illustrates how the method can be implemented in operational practice.
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Kaspar, M., and M. Müller. "Selection of historic heavy large-scale rainfall events in the Czech Republic." Natural Hazards and Earth System Sciences 8, no. 6 (2008): 1359–67. http://dx.doi.org/10.5194/nhess-8-1359-2008.
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Abstract. The Central European floods of July 1997 and August 2002 spotlighted the need for systematic research of the relationships between synoptic-scale conditions and heavy large-scale rainfalls. Creating a set of historic events underlies such research. We defined the criterion for their selection, which is based on daily areal precipitation amounts in predefined sub-regions. To stress the hydrological responses of precipitation, the criterion expresses the temporal distribution of daily areal precipitation in a three-day period. We applied the criterion to clusters of the Czech Republic river basins that were affected by high areal precipitation almost simultaneously during individual events. Finally, we selected events with the ten highest criterion values within each cluster during the warmer half-years from 1951 to 2006. Regarding the spatial extent of heavy rainfalls, we identified a few events during which a substantial part of the Czech Republic was affected. The events include, for instance, the floods of July 1997 and August 2002 that were unique in terms of precipitation totals. The uniqueness of the event in 2002 is that it consisted of two episodes that occurred in rapid succession and demonstrated heavy rainfall that affected almost the same area. Regarding the spatial distribution of precipitation, we identified several groups of events in which heavy rainfall affected similar sub-regions of the Czech Republic. This attribute was most likely related to similar synoptic-scale conditions. In terms of the seasonal variability, the most significant events were concentrated in high summer, which is typical of orographically exposed clusters. Interannual variability of the events was characterized by two main ten-year periods with a rather low frequency of occurrence followed by the years with increased frequency. The analysis of both the hydrological responses and synoptic-dynamic conditions of the events will be the object of further research.
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Maier, Roman, Gerald Krebs, Markus Pichler, Dirk Muschalla, and Günter Gruber. "Spatial Rainfall Variability in Urban Environments—High-Density Precipitation Measurements on a City-Scale." Water 12, no. 4 (2020): 1157. http://dx.doi.org/10.3390/w12041157.
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Rainfall runoff models are frequently used for design processes for urban infrastructure. The most sensitive input for these models is precipitation data. Therefore, it is crucial to account for temporal and spatial variability of rainfall events as accurately as possible to avoid misleading simulation results. This paper aims to show the significant errors that can occur by using rainfall measurement resolutions in urban environments that are too coarse. We analyzed the spatial variability of rainfall events from two years with the validated data of 22 rain gauges spread out over an urban catchment of 125 km2. By looking at the interstation correlation of the rain gauges for different classes of rainfall intensities, we found that rainfall events with low and intermediate intensities show a good interstation correlation. However, the correlation drops significantly for heavy rainfall events suggesting higher spatial variability for more intense rainstorms. Further, we analyzed the possible deviation from the spatial rainfall interpolation that uses all available rain gauges when reducing the number of rain gauges to interpolate the spatial rainfall for 24 chosen events. With these analyses we found that reducing the available information by half results in deviations of up to 25% for events with return periods shorter than one year and 45% for events with longer return periods. Assuming uniformly distributed rainfall over the entire catchment resulted in deviations of up to 75% and 125%, respectively. These findings are supported by the work of past research projects and underline the necessity of a high spatial measurement density in order to account for spatial variability of intense rainstorms.
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Zillgens, B., B. Merz, R. Kirnbauer, and N. Tilch. "Analysis of the runoff response of an Alpine catchment at different scales." Hydrology and Earth System Sciences Discussions 2, no. 5 (2005): 1923–60. http://dx.doi.org/10.5194/hessd-2-1923-2005.
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Abstract. To understand how hydrological processes are related across different spatial scales, 201 rainfall runoff events were examined in three nested catchments of the upper river Saalach in the Austrian Alps. The Saalach basin is a nested catchment covering different spatial scales, from the micro-scale (Limberg, 0.07 km2), to the small-catchment scale (Rammern, 15.5 km2), and the meso-scale (Viehhofen, 150 km2). At these three scales two different event types could clearly be identified, depending on rainfall characteristics and initial baseflow level: (1) a unimodal event type with a quick rising and falling hydrograph, responding to short duration rainfall, and (2) a bimodal event type with a double peak hydrograph at the micro-scale and substantially increased flow values at the larger basins Rammern and Viehhofen, responding to long duration rainfall events. In all cases where a bimodal event was identified at the microscale, the hydrographs at the larger scales exhibited significantly attenuated recession behavior, quantified by recession constants. At all scales, the bimodal events are associated with considerably higher runoff volumes than the unimodal events. From the investigations at the headwater Limberg we came to the conclusion that the higher amount of runoff of bimodal events is due to the mobilization of subsurface flow processes. The analysis shows that the occurrence of the two event types is consistent over three orders of magnitude in area. This link between the scales means that the runoff behavior of the headwater may be used as an indicator of the runoff behavior of much larger areas.
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Zillgens, B., B. Merz, R. Kirnbauer, and N. Tilch. "Analysis of the runoff response of an alpine catchment at different scales." Hydrology and Earth System Sciences 11, no. 4 (2007): 1441–54. http://dx.doi.org/10.5194/hess-11-1441-2007.
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Abstract. To understand how hydrological processes are related across different spatial scales, 201 rainfall runoff events were examined in three nested catchments of the upper river Saalach in the Austrian Alps. The Saalach basin is a nested catchment covering different spatial scales, from the micro-scale (Limberg, 0.07 km²), to the small-catchment scale (Rammern, 15.5 km²), and the meso-scale (Viehhofen, 150 km²). At these three scales two different event types could clearly be identified, depending on rainfall characteristics and initial baseflow level: (1) a unimodal event type with a quick rising and falling hydrograph, responding to short duration rainfall, and (2) a bimodal event type with a double peak hydrograph at the micro-scale and substantially increased flow values at the larger basins Rammern and Viehhofen, responding to long duration rainfall events. In all cases where a bimodal event was identified at the microscale, the hydrographs at the larger scales exhibited significantly attenuated recession behavior, quantified by recession constants. At all scales, the bimodal events are associated with considerably higher runoff volumes than the unimodal events. From the investigations at the headwater Limberg we came to the conclusion that the higher amount of runoff of bimodal events is due to the mobilization of subsurface flow processes. The analysis shows that the occurrence of the two event types is consistent over three orders of magnitude in area. This link between the scales means that the runoff behavior of the headwater may be used as an indicator of the runoff behavior of much larger areas.
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Hamada, Atsushi, and Yukari N. Takayabu. "Large-Scale Environmental Conditions Related to Midsummer Extreme Rainfall Events around Japan in the TRMM Region." Journal of Climate 31, no. 17 (2018): 6933–45. http://dx.doi.org/10.1175/jcli-d-17-0632.1.
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The precipitation characteristics of extreme events in August determined from 13 years of satellite data around Japan in the TRMM observation region and their relationship with large-scale environmental conditions are examined. Two types of extreme events, extreme rainfall and extreme convective events, are defined in each analysis grid box using maximum near-surface rainfall and maximum 40-dB Z echo-top height in each event, respectively. There are clear differences in precipitation characteristics between the two types of extreme events. Extreme rainfall events are more organized precipitation systems than the extreme convective events, with relatively lower echo-top heights and very low lightning activity. There are also clear differences in the related environmental conditions, where the environments related to the extreme rainfall events are somewhat convectively stable and very humid in almost the entire troposphere. These facts are consistent with our previous studies and reinforce the importance of warm-rain processes in extremely intense precipitation productions. The environments related to the extreme rainfall events exhibit a zonally extended moist anomaly in the free troposphere from southern China to the east of Japan, indicating that the excessive moisture transported from the west by a large-scale flow may partially play a role in producing environmental conditions favorable for extreme rainfall. On the other hand, the environments related to extreme convective events are not associated with free-tropospheric moisture inflow. The relationships with the tropical cyclones and upper-tropospheric dynamical fields are also examined, and are found to be clearly different between the extreme rainfall events and extreme convective events.
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Brasil, José Bandeira, Maria Simas Guerreiro, Eunice Maia de Andrade, Helba Araújo de Queiroz Palácio, Pedro Henrique Augusto Medeiros, and Jacques Carvalho Ribeiro Filho. "Minimum Rainfall Inter-Event Time to Separate Rainfall Events in a Low Latitude Semi-Arid Environment." Sustainability 14, no. 3 (2022): 1721. http://dx.doi.org/10.3390/su14031721.
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Water scarcity in dry tropical regions is expected to intensify due to climate change. Characterization of rainfall events is needed for a better assessment of the associated hydrological processes, and the proposition of adaptation strategies. There is still no consensus on the most appropriate method to separate rainfall events from a continuous database, although the minimum inter-event time (MIET) is a commonly used criterion. Semi-arid regions of low latitudes hold a distinct rainfall pattern compared to their equivalent at higher latitudes; these seasonally dry tropical forests experience strong spatial–temporal variability with intense short-duration rainfall events, which, in association with high energy surplus and potential evaporation, leads to an atmospheric water deficit. In this study, we identified the most adequate MIET based on rainfall data continuously measured at 5-min intervals over the last decade (2009–2020) in the semi-arid northeast of Brazil. The rainfall events were grouped according to different MIETs: 15 min, 1 h, 2 h, 3 h, 6 h, 12 h, and 24 h to determine rainfall depth, duration and intensity at intervals of 5, 30, and 60 min, time between events, and respective temporal distribution, with and without single tip events. Including single tip events in the dataset affected the number of rainfall events and respective characteristics up to a MIET of 3 h. A MIET of 6 h is the most appropriate to characterize the rainfall distribution in this tropical semi-arid region. Three classes were defined based on rainfall depth, duration, and intensity: I-small events (77% below 40 mm and 32 mm/h), II-high intensity events (3% between 36 and 76 mm/h), III-longer events of higher depth (20%). This study is useful for understanding how the MIET relates to other ecohydrological processes and provides more precise information on the rainfall characteristics at the event scale.
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Calenda, G., E. Gorgucci, F. Napolitano, A. Novella, and E. Volpi. "Multifractal analysis of radar rainfall fields over the area of Rome." Advances in Geosciences 2 (August 17, 2005): 293–99. http://dx.doi.org/10.5194/adgeo-2-293-2005.
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Abstract. A scale-invariance analysis of space and time rainfall events monitored by meteorological radar over the area of Rome (Italy) is proposed. The study of the scale-invariance properties of intense precipitation storms, particularly important in flood forecast and risk mitigation, allows to transfer rainfall information from the large scale predictive meteorological models to the small scale hydrological rainfall-runoff models. Precipitation events are monitored using data collected by the polarimetric Doppler radar Polar 55C (ISAC-CNR), located 15 km Southeast from downtown. The meteorological radar provides the estimates of rainfall intensity over an area of about 10 000 km2 at a resolution of 2×2 km2 in space and 5 min in time. Many precipitation events have been observed from autumn 2001 up to now. A scale-invariance analysis is performed on some of these events with the aim at exploring the multifractal properties and at understanding their dependence on the meteorological large-scale conditions.
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Liu, Hong-Bo, Jing Yang, Da-Lin Zhang, and Bin Wang. "Roles of Synoptic to Quasi-Biweekly Disturbances in Generating the Summer 2003 Heavy Rainfall in East China." Monthly Weather Review 142, no. 2 (2014): 886–904. http://dx.doi.org/10.1175/mwr-d-13-00055.1.
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Abstract During the mei-yu season of the summer of 2003, the Yangtze and Huai River basin (YHRB) encountered anomalously heavy rainfall, and the northern YHRB (nYHRB) suffered a severe flood because of five continuous extreme rainfall events. A spectral analysis of daily rainfall data over YHRB reveals two dominant frequency modes: one peak on day 14 and the other on day 4 (i.e., the quasi-biweekly and synoptic-scale mode, respectively). Results indicate that the two scales of disturbances contributed southwesterly and northeasterly anomalies, respectively, to the mei-yu frontal convergence over the southern YHRB (sYHRB) at the peak wet phase. An analysis of bandpass-filtered circulations shows that the lower and upper regions of the troposphere were fully coupled at the quasi-biweekly scale, and a lower-level cyclonic anomaly over sYHRB was phase locked with an anticyclonic anomaly over the Philippines. At the synoptic scale, the strong northeasterly components of an anticyclonic anomaly with a deep cold and dry layer helped generate the heavy rainfall over sYHRB. Results also indicate the passages of five synoptic-scale disturbances during the nYHRB rainfall. Like the sYHRB rainfall, these disturbances originated from the periodical generations of cyclonic and anticyclonic anomalies at the downstream of the Tibetan Plateau. The nYHRB rainfalls were generated as these disturbances moved northeastward under the influence of monsoonal flows and higher-latitude eastward-propagating Rossby wave trains. It is concluded that the sYHRB heavy rainfall resulted from the superposition of quasi-biweekly and synoptic-scale disturbances, whereas the intermittent passages of five synoptic-scale disturbances led to the flooding rainfall over nYHRB.
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Pui, Alexander, Ashish Sharma, Agus Santoso, and Seth Westra. "Impact of the El Niño–Southern Oscillation, Indian Ocean Dipole, and Southern Annular Mode on Daily to Subdaily Rainfall Characteristics in East Australia." Monthly Weather Review 140, no. 5 (2012): 1665–82. http://dx.doi.org/10.1175/mwr-d-11-00238.1.
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Abstract The relationship between seasonal aggregate rainfall and large-scale climate modes, particularly the El Niño–Southern Oscillation (ENSO), has been the subject of a significant and ongoing research effort. However, relatively little is known about how the character of individual rainfall events varies as a function of each of these climate modes. This study investigates the change in rainfall occurrence, intensity, and storm interevent time at both daily and subdaily time scales in east Australia, as a function of indices for ENSO, the Indian Ocean dipole (IOD), and the southern annular mode (SAM), with a focus on the cool season months. Long-record datasets have been used to sample a large variety of climate events for better statistical significance. Results using both the daily and subdaily rainfall datasets consistently show that it is the occurrence of rainfall events, rather than the average intensity of rainfall during the events, which is most strongly influenced by each of the climate modes. This is shown to be most likely associated with changes to the time between wet spells. Furthermore, it is found that despite the recent attention in the research literature on other climate modes, ENSO remains the leading driver of rainfall variability over east Australia, particularly farther inland during the winter and spring seasons. These results have important implications for how water resources are managed, as well as how the implications of large-scale climate modes are included in rainfall models to best capture interannual and longer-scale variability.
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Ferguson, Christobel M., Cheryl M. Davies, Christine Kaucner, et al. "Field scale quantification of microbial transport from bovine faeces under simulated rainfall events." Journal of Water and Health 5, no. 1 (2006): 83–95. http://dx.doi.org/10.2166/wh.2006.050.
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The dispersion and transport of Cryptosporidium parvum oocysts, Escherichia coli and PRD1 bacteriophage seeded into artificial bovine faecal pats was studied during simulated rainfall events. Experimental soil plots were divided in two, one sub-plot with bare soil and the other with natural vegetation. Simulated rainfall events of 55 mm.h-1 for 30 min were then applied to the soil plots. Each experimental treatment was performed in duplicate and consisted of three sequential artificial rainfall events (‘Runs’): a control run (no faecal pats); a fresh faecal pat run (fresh faecal pats); and an aged faecal pat run (one week aged faecal pats). Transportation efficiency increased with decreasing size of the microorganism studied; Cryptosporidium oocysts were the least mobile followed by E. coli and then PRD1 phage. Rainfall events mobilised 0.5 to 0.9% of the Cryptosporidium oocysts, 1.3‒1.4% of E. coli bacteria, and 0.03‒0.6% of PRD1 bacteriophages from the fresh faecal pats and transported them a distance of 10 m across the bare soil sub-plots. Subsequent rainfall events applied to aged faecal pats only mobilised 0.01‒0.06% of the original Cryptosporidium oocyst load, between 0.04 and 15% of the E. coli load and 0.0006‒0.06% of PRD1 bacteriophages, respectively.
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Kwak, Myeong Ja, Jongkyu Lee, Sanghee Park, et al. "Understanding Particulate Matter Retention and Wash-Off during Rainfall in Relation to Leaf Traits of Urban Forest Tree Species." Horticulturae 9, no. 2 (2023): 165. http://dx.doi.org/10.3390/horticulturae9020165.
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Dynamic particulate matter (PM) behavior on leaves depends on rainfall events, leaf structural and physical properties, and individual tree crowns in urban forests. To address this dependency, we compared the observed relationships between PM wash-off ability and leaf traits on inner and outer crown-positioned leaves during rainfall events. Data showed significant differences in the PM wash-off ability between inner and outer crown-positioned leaves relative to rainfall events due to leaf macro- and micro-structure and geometric properties among tree species. Our results showed that PM wash-off effects on leaf surfaces were negatively associated with trichome density and size of leaf micro-scale during rainfall events. Specifically, Quercus acutissima with dense trichomes and micro-level surface roughness with narrow grooves on leaf surfaces showed lower total PM wash-off in both inner (−38%) and outer (105%) crowns during rainfall. Thus, their rough leaves in the inner crown might newly capture and/or retain more PM than smooth leaves even under rainfall conditions. More importantly, Euonymus japonicus, with a thin film-like wax coverage without trichome, led to higher total PM wash-off in both inner (368%) and outer (629%) crowns during rainfall. Furthermore, we studied the changes in PM wash-off during rainfall events by comparing particle size fractions, revealing a very significant association with macro-scale, micro-scale, and geometric features.
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Cerón, Wilmar L., Nilton Díaz, Daniel Escobar-Carbonari, et al. "Multiscale Interactions of Climate Variability and Rainfall in the Sogamoso River Basin: Implications for the 1998–2000 and 2010–2012 Multiyear La Niña Events." Water 14, no. 22 (2022): 3635. http://dx.doi.org/10.3390/w14223635.
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In this research, we explored rainfall variability in the Sogamoso River Basin (SRB), its relationship with multiple scales of variability associated with El Niño–Southern Oscillation (ENSO), and the implications for rainfall prolongation during multiyear La Niña events. First, we examined time-frequency rainfall variations in the SRB based on the standardized precipitation index (SPI) from 1982 to 2019, using wavelet transform and principal component analysis (PCA). In addition, we applied wavelet analysis to investigate the links at different time scales between ENSO and the main mode of rainfall variability in the SRB. Finally, we explored the role that each scale of variability played in the prolongation and intensity of rainfall in the SRB during the 1998–2000 and 2010–2012 multiyear La Niña events. The results of the wavelet analyses revealed significant ENSO relationships affecting SRB rainfall at three different scales: quasi-biennial (2–3-years) between 1994 and 2002, as well as from 2008 to 2015; interannual (5–7 years) from 1995 to 2011; and quasi-decadal (9–12 years) from 1994 to 2012. This indicates that multiyear events are a consequence of the interaction of several scales of variability rather than a unique scale. During the 1998–2000 event, El Niño conditions were observed during the first half of 1998; subsequently, a cooling of the central and eastern tropical Pacific (western tropical Pacific) on the quasi-biennial (interannual) scale was observed during 1999; in 2000, only La Niña conditions were observed on the interannual scale. Therefore, during this event, the quasi-biennial (interannual) scale promoted wet conditions in the Caribbean, the Andes, and the Colombian Pacific from June–August (JJA) 1998 to JJA 1999 (during 1999–2000). During the 2010–2012 La Niña event, the interbasin sea surface temperature gradient between the tropical Pacific and tropical North Atlantic contributed to strengthening (weakening) of the Choco jet (Caribbean low-level jet) on the quasi-biennial scale during 2010, and the interannual scale prolonged its intensification (weakening) during 2011–2012, acting to extend the rainy periods over most of the Colombian territory. Variations on quasi-decadal scales were modulated by the Pacific decadal oscillation (PDO), resulting in a further intensification of the 2010–2012 La Niña event, which developed under conditions of the cold PDO (CPDO) phase, whereas the 1998–2000 La Niña occurred during the transition from warm (WPDO, 1977–1998) to cold (CPDO, 2001–2015) conditions. These results indicate that the interaction of quasi-biennial to quasi-decadal scales of variability could play a differential role in the configuration and prolongation of rainfall events in the SRB.
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Stoof, C. R., R. W. Vervoort, J. Iwema, E. van den Elsen, A. J. D. Ferreira, and C. J. Ritsema. "Hydrological response of a small catchment burned by experimental fire." Hydrology and Earth System Sciences 16, no. 2 (2012): 267–85. http://dx.doi.org/10.5194/hess-16-267-2012.
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Abstract. Fire can considerably change hydrological processes, increasing the risk of extreme flooding and erosion events. Although hydrological processes are largely affected by scale, catchment-scale studies on the hydrological impact of fire in Europe are scarce, and nested approaches are rarely used. We performed a catchment-scale experimental fire to improve insight into the drivers of fire impact on hydrology. In north-central Portugal, rainfall, canopy interception, streamflow and soil moisture were monitored in small shrub-covered paired catchments pre- and post-fire. The shrub cover was medium dense to dense (44 to 84%) and pre-fire canopy interception was on average 48.7% of total rainfall. Fire increased streamflow volumes 1.6 times more than predicted, resulting in increased runoff coefficients and changed rainfall-streamflow relationships – although the increase in streamflow per unit rainfall was only significant at the subcatchment-scale. Fire also fastened the response of topsoil moisture to rainfall from 2.7 to 2.1 h (p = 0.058), and caused more rapid drying of topsoils after rain events. Since soil physical changes due to fire were not apparent, we suggest that changes resulting from vegetation removal played an important role in increasing streamflow after fire. Results stress that fire impact on hydrology is largely affected by scale, highlight the hydrological impact of fire on small scales, and emphasize the risk of overestimating fire impact when upscaling plot-scale studies to the catchment-scale. Finally, they increase understanding of the processes contributing to post-fire flooding and erosion events.
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Reed, D. W., D. S. Faulkner, and E. J. Stewart. "The FORGEX method of rainfall growth estimation II: Description." Hydrology and Earth System Sciences 3, no. 2 (1999): 197–203. http://dx.doi.org/10.5194/hess-3-197-1999.
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Abstract. The Focused Rainfall Growth Extension (FORGEX) method produces rainfall growth curves focused on a subject site. Focusing allows the incorporation of rainfall extremes observed regionally while respecting local variations in growth rates. The starting point for the analysis is an extensive set of annual maximum rainfalls, with values at each gauged site standardized by the median. Following the philosophy of the earlier FORGE method, a strongly empirical approach is adopted. The rainfall growth curve is represented by linear segments on a Gumbel scale, and is fitted by a least-squares criterion. The selection of data points is intricate and includes both the traditional pooling of regional extremes and the incorporation of network maximum events. The latter comprise the largest events from successive hierarchical networks of gauges, focused on the site for which estimates are requires. Their treatment takes account of interdependence using the Dales and Reed model of spatial dependence in rainfall extremes.
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Reyers, Mark, Christoph Boehm, Leon Knarr, Yaping Shao, and Susanne Crewell. "Synoptic-to-Regional-Scale Analysis of Rainfall in the Atacama Desert (18°–26°S) Using a Long-Term Simulation with WRF." Monthly Weather Review 149, no. 1 (2021): 91–112. http://dx.doi.org/10.1175/mwr-d-20-0038.1.
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AbstractIn this study, reanalysis data and a long-term simulation with the regional climate model WRF (1982–2017; 10 km resolution) is used to analyze synoptic and regional processes associated with rainfall events in the Atacama Desert. Five composites, each with 10 WRF-simulated rainfall events, are studied. They are selected based on a clustering and comprise the top winter events in South Atacama (23°–26°S), Southeast Atacama, and North Atacama (18°–23°S), and the top summer events in North Atacama and Northeast Atacama. Winter rainfall events in South Atacama are mostly associated with strong low pressure systems over the southeast Pacific and atmospheric rivers at their foreside, while cutoff lows occurring anomalously far north facilitate strong rainfall in North Atacama. Accordingly, tropical continental areas and the remote tropical and subtropical Pacific are identified as primary moisture sources, and moisture transport toward the Atacama Desert mainly takes place in the free troposphere (above 800 hPa). Strong summer rainfall events in North Atacama and Northeast Atacama are associated with a southward displaced Bolivian high. During rainfall events in North Atacama the high is shifted westward when compared to the Northeast Atacama events. Consequently, northern Chile is located at the northern periphery of the Bolivian high and the resulting strong easterlies may push strong convective systems from the Altiplano, toward the Atacama coast. Detailed analyses of individual rainfall events reveal that the most important synoptic patterns associated with rainfall not only control the synoptic-scale moisture transport into the Atacama Desert, but also decisively influence the regional atmospheric circulation.
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McCorkle, Taylor A., Skylar S. Williams, Timothy A. Pfeiffer, and Jeffrey B. Basara. "Atmospheric Contributors to Heavy Rainfall Events in the Arkansas-Red River Basin." Advances in Meteorology 2016 (2016): 1–15. http://dx.doi.org/10.1155/2016/4597912.
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This study analyzed the top 1% 24-hour rainfall events from 1994 to 2013 at eight climatological sites that represent the east to west precipitation gradient across the Arkansas-Red River Basin in North America. A total of 131 cases were identified and subsequently classified on the synoptic-scale, mesoscale, and local-scale to compile a climatological analysis of these extreme, heavy rainfall events based on atmospheric forcings. For each location, the prominent midtropospheric pattern, mesoscale feature, and predetermined thermodynamic variables were used to classify each 1% rainfall event. Individual events were then compared with other cases throughout the basin. The most profound results were that the magnitudes of the thermodynamic variables such as convective available potential energy and precipitable water values were poor predictors of the amount of rainfall produced in these extreme events. Further, the mesoscale forcings had more of an impact during the warm season and for the westernmost locations, whereas synoptic forcings were extremely prevalent during the cold season at the easternmost locations in the basin. The implications of this research are aimed at improving the forecasting of heavy precipitation at individual weather forecasts offices within the basin through the identified patterns at various scales.
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Hamidi, Ali, Naresh Devineni, James F. Booth, Amana Hosten, Ralph R. Ferraro, and Reza Khanbilvardi. "Classifying Urban Rainfall Extremes Using Weather Radar Data: An Application to the Greater New York Area." Journal of Hydrometeorology 18, no. 3 (2017): 611–23. http://dx.doi.org/10.1175/jhm-d-16-0193.1.
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Abstract Extreme rainfall events, specifically in urban areas, have dramatic impacts on society and can lead to loss of life and property. Despite these hazards, little is known about the city-scale variability of heavy rainfall events. In the current study, gridded stage IV radar data from 2002 to 2015 are employed to investigate the clustering and the spatial variability of simultaneous rainfall exceedances in the greater New York area. Multivariate clustering based on partitioning around medoids is applied to the extreme rainfall events’ average intensity and areal extent for the 1- and 24-h accumulated rainfall during winter (December–February) and summer (June–August) seasons. The atmospheric teleconnections of the daily extreme event for winter and summer are investigated using compositing of ERA-Interim. For both 1- and 24-h durations, the winter season extreme rainfall events have larger areal extent than the summer season extreme rainfall events. Winter extreme events are associated with deep and organized circulation patterns that lead to more areal extent, and the summer events are associated with localized frontal systems that lead to smaller areal extents. The average intensities of the 1-h extreme rainfall events in summer are much higher than the average intensities of the 1-h extreme rainfall events in winter. A clear spatial demarcation exists within the five boroughs in New York City for winter extreme events. Resultant georeferenced cluster maps can be extremely useful in risk analysis and green infrastructures planning as well as sewer systems’ management at the city scale.
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Bomfim, Osmar Evandro Toledo, and Djane Fonseca da Silva. "Wavelet analysis of rainfall data of the aguapeí -peixe hydrographic basins (state of São Paulo)." Acta Scientiarum. Technology 41, no. 1 (2019): 37753. http://dx.doi.org/10.4025/actascitechnol.v41i1.37753.
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With the use of the Wavelet analysis, this study aimed to detect the dominant oscillations and phenomena that influence the occurrence of extreme rainfall events in the basins of the Aguapeí River and the Peixe River in order to generate information useful to water management. Rainfall data from 18 stations in the State of São Paulo were used, in the period from 1958 to 2013, obtained through the National Water Agency (ANA). The temporal scales that influence the rainfall and the occurrence of extreme events at each rainfall station of the basins were identified, in which the approximately 22-year scale related to the Pacific Decadal Oscillation (PDO) was the dominant in all rainfall stations. The study pointed out that the association of different temporal scales contributes to the increase in the rainfall index, on the other hand, the lack of them relates to years of low rainfall index.
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Sleziak, Patrik, Michal Danko, Martin Jančo, Juraj Parajka, and Ladislav Holko. "Spatial and temporal variability of saturated areas during rainfall-runoff events." Journal of Hydrology and Hydromechanics 71, no. 4 (2023): 439–48. http://dx.doi.org/10.2478/johh-2023-0025.
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Abstract Spatially distributed hydrological model Mike SHE was used as a diagnostic tool to provide information on possible overland flow source areas in the mountain catchment of Jalovecký Creek (area 22.2 km2, elevation range 820–2178 m a.s.l.) during different rainfall-runoff events. Selected events represented a sequence of several smaller, consecutive events, a flash flood event and two large events caused by frontal precipitation. Simulation of hourly runoff was better for runoff events caused by heavy rainfalls of longer duration than for the flash flood or consecutive smaller runoff events. Higher soil moisture was simulated near the streamflow network and larger possibly saturated areas were located mainly in the upper parts of mountain valleys. The most pronounced increase in the areal extent of possibly saturated areas (from 6.5% to 68.6% of the catchment area) was simulated for the event with high peak discharge divided by a short rainfall interruption. Rainfall depth exceeding 100 mm caused a large increase in the potentially saturated areas that covered subsequently half of the catchment area or more. A maximum integral connectivity scale representing the average distance over which individual pixels were connected varied for the selected events between 45 and 6327 m.
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Ali, Asif, and Hafiz Umar Farid. "Evaluation and Performance of SM2-Satellite Precipitation Product with Reference to Ground-Based Observations, in different cities of Pakistan." NUST Journal of Engineering Sciences 15, no. 1 (2022): 30–43. http://dx.doi.org/10.24949/njes.v15i1.675.
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Rainfall is the fundamental component to drive globalized hydrological cycle. Satellite-based precipitation having great inherency over land with wider range of applications, but their validation is at risk due to lack of rain gauge observations in different regions of the world. All precipitation product community are used to monitor the substitute data of rainfall in water resources, climatology, hydrology, meteorology, and geography. This research paper calculated the performance of SM2 precipitation product on different region, climate, elevation, and rainfall rate. For investigation, the ten statistical metrics and three categorical statistic have been analyzed at 11 station over 12 years period from 2007 to 2018. The different statistical technique assessed the analysis of precipitation product at different temporal scales (monthly, seasonally, and yearly) to investigate performance score. On the monthly and yearly time scales, product was less reliable with low correlation (0.0057 to 0.67) vary with elevation but best correlation (0.81) and linear regression coefficient (1.02) was calculated at seasonal scale than rest scales. The rainfall captured rate at seasonal scale with (>80%) was more than another scale. The outcome of this product from satellite community is less at monthly scale with significantly under and overestimation and with BIAS (-34.08% to 132.45%) than seasonal and yearly scale. But slightly over and underestimation pattern exist at seasonal scale with BIAS score (5.13% to -19.61%). During winter, research product reduces its systematic bias, NMAE and NRMSE and maintains its potential at also another seasons. The impact of elevation and different rainfall events are also investigated to detect the performance of SM2 satellite. More intense precipitation was captured by SPPs SM2 with high score of POD (> 0.70 to 0.99) vary with respect to more elevation area. The elevation trend increasing gradually from south (near mean sea level) to the northwest (northern areas of Pakistan) that having complex topography with intense rainfall rate. Same interpolated pattern of precipitation were assessed from south to northern areas of Pakistan like elevation using Arc GIS software. The overall evaluated results shows that precipitation product can detect heavy precipitation events easily than less intense events at monthly and yearly scale but reliable to capture at seasonal scale. This SPP is not completely reliable for low precipitation event with high altitude.
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Nguyen, Quan Trong, Nhi Thi Thao Pham, and Khoi Nguyen Dao. "Developing IDF curve of extreme rainfall at Tan Son Hoa station for the period 1980-2015." Science & Technology Development Journal - Science of The Earth & Environment 1, no. M2 (2017): 73–81. http://dx.doi.org/10.32508/stdjsee.v1im2.447.
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Recently, the Intensity – Duration – Frequency (IDF) relationship of extreme rainfalls in a local area is usually investigated to provide accurate required data for calculating, planning, and developing urban drainage systems, especially in the context of climate change. Traditionally, IDF curves are computed based on a statistical method for analyzing the frequency of occurrence or non-occurrence of annual extreme rainfall events over a return period; or based on a probability distribution function of these events. However, these traditional methods do not take into consideration the relationship between extreme rainfalls of different durations as they only simulate the intensity of extreme rainfall events at each individual duration after generated a large number of parameter sets. Therefore, the results of these methods are inaccurate and much depend on the actual observed data. In this study, a new approach to develop IDF relations was proposed based on the scale-invariance nature of extreme rainfalls at different durations. This method will be examined and compared with traditional methods based on the IDF curves of extreme rainfalls at Tan Son Nhat gauge station (HCMC) from 1980 to 2015. Results have indicated that there is a linear relationship between extreme rainfalls at different time scales and showed that the proposed method is appropriate for estimating the IDF curves with many prominent advantages rather than traditional method.
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Stoof, C. R., R. W. Vervoort, J. Iwema, E. van den Elsen, A. J. D. Ferreira, and C. J. Ritsema. "Hydrological response of a small catchment burned by experimental fire." Hydrology and Earth System Sciences Discussions 8, no. 2 (2011): 4053–98. http://dx.doi.org/10.5194/hessd-8-4053-2011.
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Abstract. Fire can considerably change hydrological processes, increasing the risk of extreme flooding and erosion events. Although hydrological processes are largely affected by scale, catchment-scale studies on the hydrological impact of fire are scarce, and nested approaches are rarely used. Taking a unique approach, we performed a catchment-scale experimental fire to improve insight into the drivers of fire impact on hydrology. In north-central Portugal, rainfall, canopy interception, streamflow and soil moisture were monitored in shrub-covered paired catchments pre- and post-fire. Post-fire runoff coefficients were higher than pre-fire, and fire changed the rainfall-streamflow relationship – although the increase in streamflow was only significant at the subcatchment-scale. Fire also increased the response of topsoil moisture to rainfall, and caused more rapid drying of topsoils after rain events. Since soil physical changes due to fire were not apparent, we suggest that changes resulting from vegetation removal played an important role in increasing streamflow after fire, namely: (1) increased effective rainfall and decreased transpiration – increasing the amount of water available for (sub)surface runoff, (2) more rapid development of soil water repellency and decreased surface water storage – increasing overland flow risk, (3) more rapid breakdown of post-fire soil water repellency – increasing infiltration during extended rain events. Results stress that fire impact on hydrology is largely affected by scale, highlight the hydrological impact of fire on small scales, and emphasize the risk of overestimating fire impact when upscaling plot-scale studies to the catchment-scale. Finally, they increase understanding of the processes contributing to post-fire flooding and erosion events.
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Da Silva, Djane Fonseca, Pedro Fernandes de Souza Neto, Silvania Donato da Silva, et al. "Identificação das causas climáticas dos eventos extremos e dos impactos dos ENOS Canônico e Modoki nas macrorregiões de Alagoas." Revista Brasileira de Geografia Física 14, no. 4 (2021): 1880–97. http://dx.doi.org/10.26848/rbgf.v14.4.p1880-1897.
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Anomalies of sea surface temperature that occur in some regions of the Equatorial Pacific Ocean are being studied because their cause different impacts and originate in different ways, are the ENOS, Modoki and Canonical. The objective of this work is to identify the climatic causes of the extreme events that occurred in the macro-regions of Alagoas, and at the same time, to compare the effects of ENOS Canonical and Modoki and their classes on the macro-regions of Alagoas. The daily precipitation data for 21 municipalities in the State of Alagoas were obtained through the National Water Agency from 1963 to 2014. EN Modoki and low promoted an increase in rainfall in the Eastern region. EN Fortes, on the other hand, caused a decrease in rainfall in the Sertão. Canonical LN events caused a significant increase in rainfall in the three macro-regions, but the effect was better in LN Forte. During the phases of the Atlantic Dipole, the negative phase generated positive SPI across the state, and in the positive phase, there was a decrease in SPI in the East, and a negative SPI record in Sertão and Agreste. The climatic causes of the extreme events were the combination of semiannual, interannual scales, scale between 1-2 years of ENOS, scale of ENOS extended and scale of 11 years (Dipole and sunspots), potentiating the local total rainfall, and for cases of drought , your absence. It was found, through cluster analysis, similarity between the SPIs of La Niña low and La Niña Canonical, and between El Niño Canonical is linked to El Niño Forte. Mathematically, the categories of El Niño and La Niña strong and weak showed better correlations with ENOS Modoki and Canonical, suggesting a pattern for Alagoas.
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Serrano-Notivoli, Roberto, Alberto Martínez-Salvador, Rafael García-Lorenzo, David Espín-Sánchez, and Carmelo Conesa-García. "Rainfall–runoff relationships at event scale in western Mediterranean ephemeral streams." Hydrology and Earth System Sciences 26, no. 5 (2022): 1243–60. http://dx.doi.org/10.5194/hess-26-1243-2022.
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Abstract. Ephemeral streams are highly dependent on rainfall and terrain characteristics and, therefore, very sensitive to minor changes in these environments. The western Mediterranean area exhibits a highly irregular precipitation regime with a great variety of rainfall events driving the flow generation on intermittent watercourses, and future climate change scenarios depict a lower magnitude and higher intensity of precipitation in this area, potentially leading to severe changes in flows. We explored the rainfall–runoff relationships in two semi-arid watersheds in southern Spain (Algeciras and Upper Mula) to model the different types of rainfall events required to generate new flow in both intermittent streams. We used a non-linear approach through generalized additive models at event scale in terms of magnitude, duration, and intensity, contextualizing resulting thresholds in a long-term perspective through the calculation of return periods. Results showed that the average ∼ 1.2 d and < 1.5 mm event was not enough to create new flows. At least a 4 d event ranging from 4 to 20 mm, depending on the watershed, was needed to ensure new flow at a high probability (95 %). While these thresholds represented low return periods, the great irregularity of annual precipitation and rainfall characteristics makes prediction highly uncertain. Almost a third of the rainfall events resulted in similar flow to or lower flow than the previous day, emphasizing the importance of lithological and terrain characteristics that lead to differences in flow generation between the watersheds.
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O, Noorshazwani, Norzaida A, and Syafrina A.H. "Evaluating Extreme Value Rainfall Using Mixed Exponential Distribution with Advanced Weather Generator." International Journal of Engineering & Technology 7, no. 4.38 (2018): 1412–15. http://dx.doi.org/10.14419/ijet.v7i4.38.27888.
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Changes in rainfall regime is one of the factors that is used to determine the impact of climate change. Climate change substantially impacted human societies and the natural environment with the many occurences of extreme weather events, namely rainfall variation, floods, droughts and rainstorms. In tropical countries such as Malaysia, the occurrence of extreme rainfalls has become more common in recent decades. Advanced Weather Generator (AWE-GEN) which uses meteorological data as input has the potential in predicting extreme events. The aim of this study is to propose and integrate the mixed exponential distribution in representing rainfall intensity using AWE-GEN model and evaluate the ability of the newly developed model in simulating extreme rainfall. Parameters of mixed exponential distribution theoretically represent light and heavy rainfall. The study site is Kemaman, Malaysia which is often affected by flood. Model input uses historical meteorological variables of forty years (1975 - 2015) at hourly scale, specifically precipitation, air temperature, relative humidity and wind speed. Results indicate the AWE-GEN model with mixed exponential distribution is capable of generating rainfall series very well and also able in capturing extreme rainfall events. The estimated parameters obtained revealed that the wet hourly series at study site is mainly dominated by the heavy rainfall at short duration. The outcome of this study could potentially be used in providing invaluable input to authorities requiring detailed rainfall data for planning and forecasts purposes.  Â
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Laz, Orpita U., Ataur Rahman, Abdullah Yilmaz, and Khaled Haddad. "Trends in sub-hourly, sub-daily and daily extreme rainfall events in eastern Australia." Journal of Water and Climate Change 5, no. 4 (2014): 667–75. http://dx.doi.org/10.2166/wcc.2014.035.
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Intensity and frequency of extreme rainfall are expected to change in future due to anthropogenic climate change; however, this change may not be uniform across spatial and temporal scale. This paper examines the trends of sub-hourly, sub-daily and daily extreme rainfall events from 38 rainfall stations located in southeast Australia. Two non-parametric tests (Mann–Kendall and Spearman Rho) were applied to detect trends at 10, 5 and 1% significance levels. The sub-hourly (6, 12, 18 and 30 min) and sub-daily (1, 2 and 6 h) annual maximum rainfall events generally showed an upward (positive) trend. However, the longer duration rainfall events (12–72 h) generally showed a downward (negative) trend. It was found that stations showing positive trends were characterized by higher elevations compared with the stations showing negative trends. This finding has important implications for urban stormwater management in the near future as most urban stormwater systems operate on a smaller catchment scale where sub-hourly and sub-daily rainfall events are used in their design.
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Cockburn, Jaclyn M. H., and Scott F. Lamoureux. "Century-scale variability in late-summer rainfall events recorded over seven centuries in subannually laminated lacustrine sediments, White Pass, British Columbia." Quaternary Research 67, no. 2 (2007): 193–203. http://dx.doi.org/10.1016/j.yqres.2006.10.003.
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AbstractFormation of annually laminated sediments in Summit Lake, White Pass, British Columbia is controlled by runoff generated by snowpack and glacier melt and major rainfall events. The 700-yr varve record is divided into two subannual series (early and late) based on sedimentological criteria and sedimentary structures within each varve. A comparison of recent subannual laminae with nearby meteorological records supports the interpretation they are formed by river discharge events generated by major snow and glacier melt events and large late-summer rainfall events. A significant correlation exists between the late subannual thickness series and the size of the largest rainfall events in late summer. The long record indicates there was an abrupt increase in the thickness and frequency of major rainfall-induced sedimentary events at the end of the seventeenth century. In addition, the frequency of laminae generated by early runoff events also increased. However, early subannual varve thickness component remains statistically the same as the thickness prior to the end of the seventeenth century. This suggests the change in varve thickness at this time is due to increases in major late-summer rainfall frequency rather than increased sediment availability caused by regional Little Ice Age glacier advances.
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Mengouna, François Xavier, N. Philippon, Derbetini A. Vondou, Vincent Moron, Marlon Maranan, and Andreas H. Fink. "Characterization of Subdaily Rainfall Events over Central Africa: Duration, Intensity, Amount, and Spatial Scale of the Storm Types." Journal of Hydrometeorology 25, no. 12 (2024): 1823–43. https://doi.org/10.1175/jhm-d-23-0067.1.
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Abstract Using half-hourly rainfall data from 14 automated weather stations over central Africa, rainfall events [≥0.1 mm (30 min)−1] characteristics are explored. A total of 10 096 wet events (WEs) were identified and classified into six storm types (STs), mostly discretized by their duration and intensity. ST 1 is very short (<1.5 h) with low rainfall intensities over a small area and contributes the least to the total rainfall (7%) but is by far the most frequent (70% of the WEs). ST 2 is short (∼1.5 h) and sudden with very intense rains and of medium spatial scale (<200 km). ST 3 is short and of medium scale too but with low intensities and rainfall amounts. ST 4 and ST 5 are of large scale and long (∼3–4 h), with high rainfall amounts so that they contribute the most to the total rainfall (29% and 20%). Last, ST 6 is the largest, longest, and rainiest, although moderately intense. A complementary classification is performed on lagged gridded rainfall fields from IMERG to document the possible space–time evolution of the rainfall field during the life cycle of WEs. Four spatial types are identified. Spatial type 1 gathers the most frequent, less intense ones. Spatial type 2 is far less frequent but pictures westward-moving rainfall patterns, probably associated with mesoscale convective systems. Two spatial types (3 and 4) are related to high-intensity near-stationary rainfall events, respectively, located to the southwest and northwest of the stations. ST 4 is mostly present at stations close to the Atlantic Ocean.
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Lee, Jeonghoon, Ungtae Kim, Sangdan Kim, and Jungho Kim. "Development and Application of a Rainfall Temporal Disaggregation Method to Project Design Rainfalls." Water 14, no. 9 (2022): 1401. http://dx.doi.org/10.3390/w14091401.
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A climate model is essential for hydrological designs considering climate change, but there are still limitations in employing raw temporal and spatial resolutions for small urban areas. To solve the temporal scale gap, a temporal disaggregation method of rainfall data was developed based on the Neyman–Scott Rectangular Pulse Model, a stochastic rainfall model, and future design rainfall was projected. The developed method showed better performance than the benchmark models. It produced promising results in estimating the rainfall quantiles for recurrence intervals of less than 20 years. Overall, the analysis results imply that extreme rainfall events may increase. Structural/nonstructural measures are urgently needed for irrigation and the embankment of new water resources.
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Shin, Mun-Ju, and Yun Choi. "Sensitivity Analysis to Investigate the Reliability of the Grid-Based Rainfall-Runoff Model." Water 10, no. 12 (2018): 1839. http://dx.doi.org/10.3390/w10121839.
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This study aimed to assess the suitability of the parameters of a physically based, distributed, grid-based rainfall-runoff model. We analyzed parameter sensitivity with a dataset of eight rainfall events that occurred in two catchments of South Korea, using the Sobol’ method. Parameters identified as sensitive responded adequately to the scale of the rainfall events and the objective functions employed. Parameter sensitivity varied depending on rainfall scale, even in the same catchment. Interestingly, for a rainfall event causing considerable runoff, parameters related to initial soil saturation and soil water movement played a significant role in low flow calculation and high flow calculation, respectively. The larger and steeper catchment exhibited a greater difference in parameter sensitivity between rainfall events. Finally, we found that setting an incorrect parameter range that is physically impossible can have a large impact on runoff simulation, leading to substantial uncertainty in the simulation results. The proposed analysis method and the results from our study can help researchers using a distributed rainfall-runoff model produce more reliable analysis results.
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Sansom, John, and James A. Renwick. "Climate Change Scenarios for New Zealand Rainfall." Journal of Applied Meteorology and Climatology 46, no. 5 (2007): 573–90. http://dx.doi.org/10.1175/jam2491.1.
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Abstract In terms of the effects of future climate change upon society, some of the most important parameters to estimate are associated with changing risks of extreme rainfall events, both floods and droughts. However, such aspects of the climate system are hard to estimate well using general circulation models (GCMs)—in particular, for a small mountainous landmass such as New Zealand. This paper describes a downscaling technique using broad-scale changes simulated by GCMs to select past analogs of future climate. The analog samples are assumed to represent an unbiased sample of future rainfall and are used to develop detailed descriptions of rainfall statistics using hidden semi-Markov models of rainfall breakpoint information. Such models are used to simulate long synthetic rainfall time series for comparison with the historical record. Results for three New Zealand sites show overall increases in rainfall with climate change, brought about largely by an increased frequency of rainfall events rather than an increase in rainfall intensity. There was little evidence for significant increases in high-intensity short-duration rainfalls at any site. Such results suggest that, although regional increases of rainfall are consistent with expected future climate changes, it may be that circulation changes, rather than temperature (and vapor pressure) changes, will be the more important determinant of future rainfall distributions, at least for the coming few decades.
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Zhang, Xinzhong, Yu Li, Qin Han, and Yuxin Zhang. "Timescale-dependent responses of hydrological changes from global closed basins since the last glacial maximum." Progress in Physical Geography: Earth and Environment 46, no. 2 (2021): 201–16. http://dx.doi.org/10.1177/03091333211051939.
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Water shortage has plagued the social development and human well-being of global closed basins. However, the hydroclimate research on different time scales in these regions remains inadequate at a global scale. In this paper, the hydrological responses from global closed basins to millennial-scale and centennial-scale cold/warm events since the Last Glacial Maximum were explored. Closed-basin lake records indicate that the westerlies-dominated closed basins are generally wetter during cold events than the corresponding warm ones on the millennial and centennial scales. In contrast, the monsoon-influenced closed basins prevail wetter climates during warm events. According to the hydroclimate simulations, precipitation seasonality plays a significant role in causing above spatial–temporal patterns. There is more winter rainfall in westerlies-dominated closed basins during cold events in the Last Glacial Maximum and Little Ice Age and more summer rainfall in monsoon-influenced closed basins during warm events in the mid-Holocene and Medieval Climate Anomaly. Under modern and future global warming, the hydroclimate changes in global closed basins show more regional differentiation, resulting in wetter mid-latitude Asian and low-latitude African closed basins but drier southwest North American and Australian closed basins.
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ten Veldhuis, Marie-Claire, Zhengzheng Zhou, Long Yang, Shuguang Liu, and James Smith. "The role of storm scale, position and movement in controlling urban flood response." Hydrology and Earth System Sciences 22, no. 1 (2018): 417–36. http://dx.doi.org/10.5194/hess-22-417-2018.
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Abstract. The impact of spatial and temporal variability of rainfall on hydrological response remains poorly understood, in particular in urban catchments due to their strong variability in land use, a high degree of imperviousness and the presence of stormwater infrastructure. In this study, we analyze the effect of storm scale, position and movement in relation to basin scale and flow-path network structure on urban hydrological response. A catalog of 279 peak events was extracted from a high-quality observational dataset covering 15 years of flow observations and radar rainfall data for five (semi)urbanized basins ranging from 7.0 to 111.1 km2 in size. Results showed that the largest peak flows in the event catalog were associated with storm core scales exceeding basin scale, for all except the largest basin. Spatial scale of flood-producing storm events in the smaller basins fell into two groups: storms of large spatial scales exceeding basin size or small, concentrated events, with storm core much smaller than basin size. For the majority of events, spatial rainfall variability was strongly smoothed by the flow-path network, increasingly so for larger basin size. Correlation analysis showed that position of the storm in relation to the flow-path network was significantly correlated with peak flow in the smallest and in the two more urbanized basins. Analysis of storm movement relative to the flow-path network showed that direction of storm movement, upstream or downstream relative to the flow-path network, had little influence on hydrological response. Slow-moving storms tend to be associated with higher peak flows and longer lag times. Unexpectedly, position of the storm relative to impervious cover within the basins had little effect on flow peaks. These findings show the importance of observation-based analysis in validating and improving our understanding of interactions between the spatial distribution of rainfall and catchment variability.
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Cheng, Chad Shouquan, Guilong Li, Qian Li, and Heather Auld. "A Synoptic Weather-Typing Approach to Project Future Daily Rainfall and Extremes at Local Scale in Ontario, Canada." Journal of Climate 24, no. 14 (2011): 3667–85. http://dx.doi.org/10.1175/2011jcli3764.1.
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Abstract This paper attempts to project possible changes in the frequency of daily rainfall events late in this century for four selected river basins (i.e., Grand, Humber, Rideau, and Upper Thames) in Ontario, Canada. To achieve this goal, automated synoptic weather typing as well as cumulative logit and nonlinear regression methods was employed to develop within-weather-type daily rainfall simulation models. In addition, regression-based downscaling was applied to downscale four general circulation model (GCM) simulations to three meteorological stations (i.e., London, Ottawa, and Toronto) within the river basins for all meteorological variables (except rainfall) used in the study. Using downscaled GCM hourly climate data, discriminant function analysis was employed to allocate each future day for two windows of time (2046–65, 2081–2100) into one of the weather types. Future daily rainfall and its extremes were projected by applying within-weather-type rainfall simulation models together with downscaled future GCM climate data. A verification process of model results has been built into the whole exercise (i.e., statistical downscaling, synoptic weather typing, and daily rainfall simulation modeling) to ascertain whether the methods are stable for projection of changes in frequency of future daily rainfall events. Two independent approaches were used to project changes in frequency of daily rainfall events: method I—comparing future and historical frequencies of rainfall-related weather types, and method II—applying daily rainfall simulation models with downscaled future climate information. The increases of future daily rainfall event frequencies and seasonal rainfall totals (April–November) projected by method II are usually greater than those derived by method I. The increase in frequency of future daily heavy rainfall events greater than or equal to 25 mm, derived from both methods, is likely to be greater than that of future daily rainfall events greater than or equal to 0.2 mm: 35%–50% versus 10%–25% over the period 2081–2100 derived from method II. In addition, the return values of annual maximum 3-day accumulated rainfall totals are projected to increase by 20%–50%, 30%–55%, and 25%–60% for the periods 2001–50, 2026–75, and 2051–2100, respectively. Inter-GCM and interscenario uncertainties of future rainfall projections were quantitatively assessed. The intermodel uncertainties are similar to the interscenario uncertainties, for both method I and method II. However, the uncertainties are generally much smaller than the projection of percentage increases in the frequency of future seasonal rain days and future seasonal rainfall totals. The overall mean projected percentage increases are about 2.6 times greater than overall mean intermodel and interscenario uncertainties from method I; the corresponding projected increases from method II are 2.2–3.7 times greater than overall mean uncertainties.
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Mohamed, Mostafa A., and Mohamed El-Sayed El-Mahdy. "Impact of sunspot activity on the rainfall patterns over Eastern Africa: a case study of Sudan and South Sudan." Journal of Water and Climate Change 12, no. 5 (2021): 2104–24. http://dx.doi.org/10.2166/wcc.2021.312.
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Abstract The relation between sunspots and rainfall patterns is still obscure in Africa, especially for Sudan and South Sudan. This research explores the response of rainfall to solar activity in eastern regions of Africa, with a case study in Sudan and South Sudan. Rainfall varies with time; therefore, skillful monitoring, predicting, and early warning of rainfall events is indispensable. Severe climatic events, such as droughts and floods, are critical factors in planning and managing all socioeconomic activities. Similar trends for the sunspot activity (sunspot number and sunspot groups) changes and rainfall variations for different stations in East Africa during the years 1910–2018 were not found. Correlation analysis carried out for the above period indicated a weak negative correlation between the total rainfall and the average number of sunspots over the long-term scale for selected stations in Sudan and South Sudan. The overall result of the paper indicated no significant relationship between sunspot numbers and rainfall in temporal and spatial scales in Sudan and South Sudan.
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Murphy, Bradley F., Scott B. Power, and Simon McGree. "The Varied Impacts of El Niño–Southern Oscillation on Pacific Island Climates." Journal of Climate 27, no. 11 (2014): 4015–36. http://dx.doi.org/10.1175/jcli-d-13-00130.1.
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Abstract El Niño–Southern Oscillation (ENSO) drives interannual climate variability in many tropical Pacific island countries, but different El Niño events might be expected to produce varying rainfall impacts. To investigate these possible variations, El Niño events were divided into three categories based on where the largest September–February sea surface temperature (SST) anomalies occur: warm pool El Niño (WPE), cold tongue El Niño (CTE), and mixed El Niño (ME), between the other two. Large-scale SST and wind patterns for each type of El Niño show distinct and significant differences, as well as shifts in rainfall patterns in the main convergence zones. As a result, November to April rainfall in many Pacific island countries is significantly different among the El Niño types. In western equatorial Pacific islands, CTE events are associated with drier than normal conditions whereas ME and WPE events are associated with significantly wetter than normal conditions. This is due to the South Pacific convergence zone and intertropical convergence zone moving equatorward and merging in CTE events. Rainfall in the convergence zones is enhanced during ME and WPE and the displacement is smaller. La Niña events also show robust impacts that most closely mirror those of ME events. In the northwest and southwest Pacific strong CTE events have much larger impacts on rainfall than ME and WPE, as SST anomalies and correspondingly large-scale surface wind and rainfall changes are largest in CTE. While variations in rainfall exist between different types of El Niño and the significant impacts on Pacific countries of each event are different, the two extreme CTE events have produced the most atypical impacts.
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Jiang, Zhihong, George Tai-Jen Chen, and Ming-Chin Wu. "Large-Scale Circulation Patterns Associated with Heavy Spring Rain Events over Taiwan in Strong ENSO and Non-ENSO Years." Monthly Weather Review 131, no. 8 (2003): 1769–82. http://dx.doi.org/10.1175//2561.1.
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Abstract Daily rainfall data at 15 stations in Taiwan and the grid dataset of the National Centers for Environmental Prediction–National Center for Atmospheric Research during the period of February–March 1951–2000 were used to reveal the characteristics of large-scale circulations associated with spring heavy rain events over Taiwan in strong ENSO and non-ENSO years. The effect of interdecadal variation on the relationship of spring rainfall and ENSO was also examined. Results showed that the different regimes of interdecadal variation that occurred in the late 1970s exert significant effect on the relationship between ENSO and spring rainfall in Taiwan. A pronounced positive correlation with statistical significance between cold season Niño-3 SST and the following spring rainfall over western Taiwan was only found since the late 1970s. Large-scale environmental conditions associated with the heavy spring rain events in strong ENSO and non-ENSO years were found to be quite different. Intrusion of a weak midlatitude frontal system into the eastern China coastal area coupled with an anomalous anticyclone over the Philippine Sea (PSAC) in the lower troposphere were primarily responsible for the spring heavy rain events in strong ENSO years. On the other hand, the intrusion of a much more intense midlatitude frontal system into China and the coastal area was necessary to generate spring heavy rain events in non-ENSO years. This difference is also instrumental for more frequent occurrence of heavy rainfall events and more rainfall amount observed in ENSO years.
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Nizar, Sinan, Jobin Thomas, P. J. Jainet, and K. P. Sudheer. "A novel technique for nowcasting extreme rainfall events using early microphysical signatures of cloud development." PLOS Climate 4, no. 5 (2025): e0000497. https://doi.org/10.1371/journal.pclm.0000497.
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Accurate forecasting of extreme rainfall events (EREs) at a regional scale with higher lead times is challenging due to the uncertainties in weather model predictions. This study introduces a novel technique to nowcast heavy- and extreme-rainfall events by analyzing early microphysical signatures in mesoscale convective clouds. The method primarily utilizes the cloud top temperature (T) - cloud effective radius (re) profiles derived using remote sensing. We estimate the probability of the occurrence of heavy- and extreme-rainfall events using a logistic regression model with attributes extracted from the T-re profile and cloud droplet size distribution. Our analysis indicates that the T-re profiles for normal-, heavy-, and extreme-rainfall events exhibit distinct microphysical characteristics, with a prominent diffusional zone during EREs. Applying this model to nowcast recent EREs in the southern Western Ghats (Kerala, India) demonstrates an overall skill score of 93% and a lead time of at least six hours, underscoring the effectiveness of the approach for nowcasting EREs at a regional scale.
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Bazzi, Hassan, Nicolas Baghdadi, Mohammad El Hajj, and Mehrez Zribi. "Potential of Sentinel-1 Surface Soil Moisture Product for Detecting Heavy Rainfall in the South of France." Sensors 19, no. 4 (2019): 802. http://dx.doi.org/10.3390/s19040802.
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The objective of this paper is to present an analysis of Sentinel-1 derived surface soil moisture maps (S1-SSM) produced with high spatial resolution (at plot scale) and a revisit time of six days for the Occitanie region located in the South of France as a function of precipitation data, in order to investigate the potential of S1-SSM maps for detecting heavy rainfalls. First, the correlation between S1-SSM maps and rainfall maps provided by the Global Precipitation Mission (GPM) was investigated. Then, we analyzed the effect of the S1-SSM temporal resolution on detecting heavy rainfall events and the impact of these events on S1-SSM values as a function of the number of days that separated the heavy rainfall and the S1 acquisition date (cumulative rainfall more than 60 mm in 24 hours or 80 mm in 48 hours). The results showed that the six-day temporal resolution of the S1-SSM map doesn’t always permit the detection of an extreme rainfall event, because confusion will appear between high S1-SSM values due to extreme rainfall events occurring six days before the acquisition of S1-SSM, and high S1-SSM values due to light rain a few hours before the acquisition of Sentinel-1 images. Moreover, the monitoring of extreme rain events using only soil moisture maps remains difficult, since many environmental parameters could affect the value of SSM, and synthetic aperture radar (SAR) doesn’t allow the estimation of very high soil moistures (higher than 35 vol.%).
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He, Shuangshuang, Jun Wang, and Songnan Liu. "Rainfall Event–Duration Thresholds for Landslide Occurrences in China." Water 12, no. 2 (2020): 494. http://dx.doi.org/10.3390/w12020494.
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A rainfall threshold for landslide occurrence at a national scale in China has rarely been developed in the early warning system for landslides. Based on 771 landslide events that occurred in China during 1998–2017, four groups of rainfall thresholds at different quantile levels of the quantile regression for landslide occurrences in China are defined, which include the original rainfall event–duration (E–D) thresholds and normalized (the accumulated rainfall is normalized by mean annual precipitation) (EMAP–D) rainfall thresholds based on the merged rainfall and the Climate Prediction Center Morphing technique (CMORPH) rainfall products, respectively. Each group consists of four sub-thresholds in rainy season and non-rainy season, and both are divided into short duration (<48 h) and long duration (≥48 h). The results show that the slope of the regression line for the thresholds in the events with long durations is larger than that with short durations. In addition, the rainfall thresholds in the non-rainy season are generally lower than those in the rainy season. The E–D thresholds defined in this paper are generally lower than other thresholds in previous studies on a global scale, and a regional or national scale in China. This might be due to there being more landslide events used in this paper, as well as the combined effects of special geological environment, climate condition and human activities in China. Compared with the previous landslide model, the positive rates of the rainfall thresholds for landslides have increased by 16%–20%, 10%–17% and 20%–38% in the whole year, rainy season and non-rainy season, respectively.
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Isidoro, Jorge Manuel Guieiro Pereira, Alexandre Silveira, and Bruno Oliveira Lima. "Development of a large-scale rainfall simulator for urban hydrology research." Engenharia Sanitaria e Ambiental 27, no. 1 (2022): 169–73. http://dx.doi.org/10.1590/s1413-415220200365.
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ABSTRACT This work presented the development and testing of a large-scale rainfall simulator (LSRS) to be used as a research tool on rainfall-runoff and associated transport processes in urban areas. The rainfall simulator consists of a pressurized water supply system which supplies a set of 16 full-cone nozzles. Artificial rainfall with different rainfall intensities can be produced over an area of 100 m2 in a V shape. The assembly is housed in a tailor-made acrylic structure to eliminate the influence of wind and natural rainfall. Runoff is measured and collected at the outlet of the drainage basin, from where it is pumped to a storage tank that enables the reuse of water. Runoff hydrographs and pollutographs are presented as examples of possible outcomes from this facility. The LSRS is showed to be able to reproduce the rainfall-runoff and pollutant transport processes under simulated rainfall events with intensity and spatial uniformity similar to other experiments described in the literature.
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Minea, Gabriel, Mihaela Iliescu, and Florin Dedu. "Temporal rainfall properties at events scale in the Curvature Subcarpathians (Romania)." Forum geografic XV, Suppl. 2 (2016): 115–23. http://dx.doi.org/10.5775/fg.2016.141.s.
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BHOWMIK, S. K. ROY. "Some dynamical aspects of meso-scale rainfall events as revealed by physical initialization." MAUSAM 49, no. 1 (2021): 11–20. http://dx.doi.org/10.54302/mausam.v49i1.3594.
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In recent years, physical initialization has emerged as a powerful tool to improve initial state of dynamical model during assimilation phase. This improved initial state at high resolution global spectral model is able to provide a tropical meso-scale coverage. In this paper, model out-put is used to study some dynamical aspects of meso-scale rainfall events. Major findings of this study are : (i) Meso-scale rainfall event carries a distinct dynamic structure in vertical profiles of divergence and vertical upward motion, (ii) Meso-scale event exhibits a large diurnal variation in these vertical profiles and (iii) Vertical motion field of meso-scale organisation appears to play a significant role in tropical storm formation.
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Abushandi, Eyad H., and Broder J. Merkel. "Application of IHACRES rainfall-runoff model to the Wadi Dhuliel arid catchment, Jordan." Journal of Water and Climate Change 2, no. 1 (2011): 56–71. http://dx.doi.org/10.2166/wcc.2011.048.
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With increasing stress on water resources in Jordan, application of rainfall-runoff models can be part of the solution to manage and sustain the water sector. In this paper, the metric conceptual IHACRES model is applied to the Wadi Dhuliel arid catchment, north-east Jordan. Rainfall-runoff data from 19 storm events during 1986 to 1992 have been used in this study. Flood estimation was performed on the basis of daily scales and storm events scales. The model was extended for snowfall in order to cope with such extreme events. Although the best performance of the IHACRES model on a daily basis is poor, the performance on storm events scale showed a good agreement between observed and simulated streamflow. Apart from model parameter values, the principal reasons for IHACRES model success in this region are thought to be based on antecedent soil moisture conditions, rainfall duration and rainfall intensity before and during each storm. The model outputs were likely to be sensitive when the monitored flood was relatively small. The optimum parameter values were influenced by the length of calibration data and event specific changes.
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Brigode, P., Z. Mićović, P. Bernardara, et al. "Linking ENSO and heavy rainfall events over coastal British Columbia through a weather pattern classification." Hydrology and Earth System Sciences 17, no. 4 (2013): 1455–73. http://dx.doi.org/10.5194/hess-17-1455-2013.
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Abstract. Classifications of atmospheric weather patterns (WPs) are widely used for the description of the climate of a given region and are employed for many applications, such as weather forecasting, downscaling of global circulation model outputs and reconstruction of past climates. WP classifications were recently used to improve the statistical characterisation of heavy rainfall. In this context, bottom-up approaches, combining spatial distribution of heavy rainfall observations and geopotential height fields have been used to define WP classifications relevant for heavy rainfall statistical analysis. The definition of WPs at the synoptic scale creates an interesting variable which could be used as a link between the global scale of climate signals and the local scale of precipitation station measurements. We introduce here a new WP classification centred on the British Columbia (BC) coastal region (Canada) and based on a bottom-up approach. Five contrasted WPs composed this classification, four rainy WPs and one non-rainy WP, the anticyclonic pattern. The four rainy WPs are mainly observed in the winter months (October to March), which is the period of heavy precipitation events in coastal BC and is thus consistent with the local climatology. The combination of this WP classification with the seasonal description of rainfall is shown to be useful for splitting observed precipitation series into more homogeneous sub-samples (i.e. sub-samples constituted by days having similar atmospheric circulation patterns) and thus identifying, for each station, the synoptic situations that generate the highest hazard in terms of heavy rainfall events. El Niño-Southern Oscillations (ENSO) significantly influence the frequency of occurrence of two coastal BC WPs. Within each WP, ENSO seem to influence only the frequency of rainy events and not the magnitudes of heavy rainfall events. Consequently, heavy rainfall estimations do not show significant evolution of heavy rainfall behaviour between Niño and Niña winters. However, the WP approach captures the variability of the probability of occurrences of synoptic situations generating heavy rainfall depending on ENSO and opening interesting perspectives for the analysis of heavy rainfall distribution in a non-stationary context.