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Ariyanto, Dwi Priyo, Abdul Aziz, Komariah Komariah, Sumani Sumani, and Magarsa Abara. "Comparing the accuracy of estimating soil moisture using the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI)." SAINS TANAH - Journal of Soil Science and Agroclimatology 17, no. 1 (June 29, 2020): 23. http://dx.doi.org/10.20961/stjssa.v17i1.41396.
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<span>The Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI) are used to monitor and identify different types of drought, including meteorological, hydrological, and agricultural droughts. This study evaluates the accuracy of estimating soil moisture levels using the two indexes. The analysis correlated the SPI and the SPEI over three years (November 2016–October 2019) using <em>Rstudio</em>, with average monthly soil moisture taken using a Soil Moisture Sensor; 3-, 6- and 12-months SPI and SPEI showed a positive correlation for soil moisture (Sig <0.05), whereas 1-month SPI and SPEI results did not. A regression test was used to get an equation model for estimating soil moisture content. The correlation for soil moisture between the 1-month SPI and SPEI results was insignificant (p-value >0.05). In contrast, the 3-, 6-, and 12-months indexes were significant (p-value <0.05). Estimating soil moisture content using the SPEI (50–59.09%) had a higher accuracy value than the SPI (36.36%), which indicates the SPEI can more reliably predict soil moisture.</span>
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Vicente-Serrano, Sergio M., Santiago Beguería, and Juan I. López-Moreno. "A Multiscalar Drought Index Sensitive to Global Warming: The Standardized Precipitation Evapotranspiration Index." Journal of Climate 23, no. 7 (April 1, 2010): 1696–718. http://dx.doi.org/10.1175/2009jcli2909.1.
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Abstract The authors propose a new climatic drought index: the standardized precipitation evapotranspiration index (SPEI). The SPEI is based on precipitation and temperature data, and it has the advantage of combining multiscalar character with the capacity to include the effects of temperature variability on drought assessment. The procedure to calculate the index is detailed and involves a climatic water balance, the accumulation of deficit/surplus at different time scales, and adjustment to a log-logistic probability distribution. Mathematically, the SPEI is similar to the standardized precipitation index (SPI), but it includes the role of temperature. Because the SPEI is based on a water balance, it can be compared to the self-calibrated Palmer drought severity index (sc-PDSI). Time series of the three indices were compared for a set of observatories with different climate characteristics, located in different parts of the world. Under global warming conditions, only the sc-PDSI and SPEI identified an increase in drought severity associated with higher water demand as a result of evapotranspiration. Relative to the sc-PDSI, the SPEI has the advantage of being multiscalar, which is crucial for drought analysis and monitoring.
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Zhao, Qingzhi, Xiongwei Ma, Wanqiang Yao, Yang Liu, and Yibin Yao. "A Drought Monitoring Method Based on Precipitable Water Vapor and Precipitation." Journal of Climate 33, no. 24 (December 15, 2020): 10727–41. http://dx.doi.org/10.1175/jcli-d-19-0971.1.
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AbstractPrecipitable water vapor (PWV) with high precision and high temporal resolution can be obtained based on the global navigation and satellite positioning system (GNSS) technique, which is important for GNSS in disaster prevention and mitigation. However, related studies on drought monitoring using PWV have rarely been performed before, which becomes the focus of this paper. This paper proposes a novel drought monitoring method using GNSS-derived PWV and precipitation, and a multi-time-scale standardized precipitation conversion index (SPCI) is established. This index is different from the traditional index in terms of expression, standardization, and time scale. The proposed SPCI is then compared with the standardized precipitation index/standardized precipitation evapotranspiration index/self-calibrating Palmer drought severity index (SPI/SPEI/scPDSI) and applied to local and global drought monitoring. Validated results show that multi-time-scale SPCI has good consistency with the corresponding SPI/SPEI/scPDSI. The correlation between SPCI and SPEI is the strongest (more than 0.96) on a 12-month scale, which indicates the application potential of SPCI in drought monitoring. In addition, applications for regional (Queensland, Australia) and global drought/wet monitoring further verify the capability of the proposed SPCI. The average percentage deviations of drought/wet monitoring between SPCI and SPEI are 2.77% and 3.75%, respectively on a global scale. The above results show that the SPCI developed in this study is efficiently applied to global flood/wet studies.
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Saengrattanayon, Chanattha, Nuttapong Panthong, Parwapath Phunthirawuthi, and Sukrit Kirtsaeng. "Analysis of Standardized Precipitation Evapotranspiration Index over Chiangrai and Phayao." Applied Mechanics and Materials 891 (May 2019): 117–26. http://dx.doi.org/10.4028/www.scientific.net/amm.891.117.
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Drought indices analysis plays a vital role in flood and drought monitoring and early warning, which is a main responsibility of Thai Meteorological Department (TMD), especially the basins that are limited in use o¬¬f water resources such as Kok and Ing river basins. This study aims to analyze drought situations utilized Standardized Precipitation Evapotranspiration Index (SPEI) at Chiangrai and Phayao provinces (located Kok and Ing basins). Both observed data, precipitation and temperature, are used for calculation (data in between 1951-2018 for Chiangrai and 1981-2018 for Phayao). The result shows that SPEI can determine drought probability and its potential impact in the observed area. This study could be applied to drought monitoring over other basins.
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S L Cheng F Y Zhang Y Q et al, Liu. "Standardized Precipitation Evapotranspiration Index (SPEI) Dataset of Yunnan Province, China." Journal of Global Change Data & Discovery 1, no. 4 (2017): 447–51. http://dx.doi.org/10.3974/geodp.2017.04.11.
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Jamro, Shoaib, Ghulam Hussain Dars, Kamran Ansari, and Nir Y. Krakauer. "Spatio-Temporal Variability of Drought in Pakistan Using Standardized Precipitation Evapotranspiration Index." Applied Sciences 9, no. 21 (October 29, 2019): 4588. http://dx.doi.org/10.3390/app9214588.
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Pakistan is among the top ten countries adversely affected by climate change. More specifically, there is concern that climate change may cause longer and severer spells of droughts. To quantify the change in the characteristics of droughts in Pakistan over the years, we have evaluated spatio-temporal trends of droughts in Pakistan over the period 1902–2015 using Standardized Precipitation Evapotranspiration Index (SPEI). Additionally, the Spatial “K” luster Analysis using Tree Edge Removal (SKATER) method was employed to regionalize droughts into five contiguous zones. The run theory was then applied to each zone to identify drought events and characterize them in terms of duration, severity, intensity, and peak. Moreover, the Modified Mann–Kendall trend test was applied to identify statistically significant trends in SPEI and drought characteristics in each zone. It was found that the southern areas of Pakistan, encompassing Sindh and most of Baluchistan, have experienced a decrease in SPEI, indicating a drying trend. Central Pakistan has witnessed a wetting trend as demonstrated by an increase in SPEI over time, whereas no statistically significant trend was observed for the northern areas of Pakistan. On a zonal basis, the longest duration drought to occur in Pakistan lasted 22 months in zone 5 (Sindh) from 1968 to 1970. In addition, the drought of 1920 and 2000 can be said to be the worst drought in the history of the region as it affected all the zones and lasted for more than 10-months in three zones.
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Ahmadebrahimpour, Edris, Babak Aminnejad, and Keivan Khalili. "Assessing future drought conditions under a changing climate: a case study of the Lake Urmia basin in Iran." Water Supply 19, no. 6 (April 12, 2019): 1851–61. http://dx.doi.org/10.2166/ws.2019.062.
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Abstract This study was conducted to assess the impacts of climate change on drought over the Lake Urmia basin, Iran. Drought events for 2011–2040, 2041–2070, and 2071–2100 were analyzed based on the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI) and were compared with the adopted baseline period (1976–2005). The SPI and SPEI were calculated using the precipitation and temperatures obtained from the second-generation Canadian Earth System Model (CanESM2) under Representative Concentration Pathway (RCP) 2.6 and RCP 8.5 as optimistic and pessimistic scenarios respectively. The results of SPI analyses revealed that under RCP 2.6 the frequency of droughts is almost constant while under RCP 8.5 drought frequency increased especially in the period 2071–2100. The calculated SEPI under both scenarios and during all future periods predict that the frequency and duration of droughts will increase. Generally, the difference between the SPI and SPEI is related to the input to each index. SPI is solely based on precipitation while the SPEI accounts for both precipitation and potential evapotranspiration (PET). Under global warming and changing climate, the significant role of PET was highlighted. It was concluded that the SPEI outperformed the SPI for drought studies under a changing climate.
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Katipoğlu, Okan Mert, Reşat Acar, and Selim Şengül. "Comparison of meteorological indices for drought monitoring and evaluating: a case study from Euphrates basin, Turkey." Journal of Water and Climate Change 11, S1 (November 11, 2020): 29–43. http://dx.doi.org/10.2166/wcc.2020.171.
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Abstract Drought incidents occur due to the fact that precipitation values are below average for many years. Drought causes serious effects in many sectors, such as agriculture, economy, health, and energy. Therefore, the determination of drought and water scarcity, monitoring, management, and planning of drought and taking early measures are important issues. In order to solve these issues, the advantages and disadvantages of five different meteorological drought indices were compared, and the most effective drought index was determined for monitoring drought. Accordingly, in the monthly, 3-month, and 12-month time period, covering the years between 1966 and 2017 (52 years), Standardized Precipitation Index (SPI), Statistical Z-Score Index (ZSI), Rainfall Anomaly Index (RAI), Standardized Precipitation Evapotranspiration Index (SPEI), and Reconnaissance Drought Index (RDI) were used. It was concluded that precipitation-based SPI and ZSI are similar patterns and precipitation, and temperature-based SPEI and RDI are similar patterns. Also, it has been determined that RAI is more effective than other indices in determining the periods of extreme drought or wet. Furthermore, SPEI and RDI have been found to be superior to other indices as they take into account the water consumption and climate effects caused by evapotranspiration.
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Gocic, Milan, Danilo Misic, Slavisa Trajkovic, and Mladen Milanovic. "Using GIS tool for presenting spatial distribution of drought." Facta universitatis - series: Architecture and Civil Engineering 18, no. 1 (2020): 77–84. http://dx.doi.org/10.2298/fuace200409006g.
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By using GIS tools, it is possible to improve the preview of hydrological processes such as evapotranspiration, precipitation, flood and drought. In order to quantify drought, different type of drought indicators have been developed such as Standardized Precipitation Index (SPI), Reconnaissance Drought Index (RDI), Standardized Precipitation Evapotranspiration Index (SPEI) or Water Surplus Variability Index (WSVI). In this paper the precipitation-based SPI indicator was applied to the monthly precipitation data from Serbia during the period 1948-2012. The data were processed in the QuantumGIS software package. For the purpose of application in the monitoring of drought at the national level, a spatial presentation of meteorological drought was obtained.
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Serrano-Barrios, L., S. M. Vicente-Serrano, H. Flores-Magdaleno, L. Tijerina-Chávez, and D. Vázquez-Soto. "Variabilidad espacio-temporal de las sequías en la cuenca Pacífico Norte de México (1961-2010)." Cuadernos de Investigación Geográfica 42, no. 1 (June 27, 2016): 185. http://dx.doi.org/10.18172/cig.2857.
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This article analyses the spatio-temporal variability of droughts in the North Pacific Basin of México between 1961 and 2010, using two drought indices: the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI). We used data from 48 weather stations with available data of precipitation and monthly minimum and maximum temperature. In 22 of the weather stations, time series of Piché evaporation were also available. The reference evapotranspiration, necessary to obtain the SPEI, was calculated by means of the Hargreaves equation. Results show that major droughts occurred in the 1980s and 2000s, although there is a noticeable spatial variability across the region. Finally, the potential impact of the atmospheric evaporative demand on drought severity observed by the different drought indices is discussed, and the possible implications for an appropriate risk assessment.
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Liu, Weilin, and Lina Liu. "Analysis of Dry/Wet Variations in the Poyang Lake Basin Using Standardized Precipitation Evapotranspiration Index Based on Two Potential Evapotranspiration Algorithms." Water 11, no. 7 (July 5, 2019): 1380. http://dx.doi.org/10.3390/w11071380.
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Global warming has resulted in unevenly distributed changes in precipitation and evapotranspiration, which has some influence on dry/wet conditions, thus exerting a tremendous impact on national life and the social economy, especially agricultural production. In order to characterize the dry/wet variations in the Poyang Lake basin during 1958–2013, based on the potential evapotranspiration (PET) estimated by the Thornthwaite (TH) and Penman–Monteith (PM) formulas, two types of Standardized Precipitation Evapotranspiration Index (SPEI), namely SPEI_th and SPEI_pm, were calculated in this study. The characteristic of dry/wet variations in the Poyang Lake basin was analyzed and a comparative analysis of two SPEIs was conducted. The results indicate that both SPEI series showed a wet trend in the Poyang Lake basin on an annual scale as well as seasonal scales during 1958–2013, except for spring and autumn. A drying trend was observed in spring, while in autumn, the dry and wet conditions in two SPEIs had opposite trends. However, all trends from two SPEIs were not significant, except for summer SPEI_pm. Meanwhile, significant positive correlations were detected between precipitation and two SPEIs, with the correlation coefficients above 0.95, whereas negative correlations were detected between PET and two SPEIs, with the correlation coefficients ranging from −0.17 to −0.85. This indicates that precipitation was the main climatic factor to determine change in dry/wet conditions in the Poyang Lake basin. Although there were obvious differences between the accumulated values of the Penman–Monteith-based PET (ET_pm) and Thornthwaite-based PET (ET_th), trends in the SPEI_pm series were generally consistent with those in the SPEI_th series, revealing that the method for PET calculation was not critical to the change in dry/wet conditions. Moreover, the results of the conditional probability of SPEI_pm and SPEI_th show that both SPEI_pm and SPEI_th could detect wet or dry events that were identified by SPEI_pm or SPEI_th.
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Fung, Kit Fai, Yuk Feng Huang, and Chai Hoon Koo. "Improvement of SVR-Based Drought Forecasting Models using Wavelet Pre-Processing Technique." E3S Web of Conferences 65 (2018): 07007. http://dx.doi.org/10.1051/e3sconf/20186507007.
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Drought is a damaging natural hazard due to the lack of precipitation from the expected amount for a period of time. Mitigations are required to reduced its impact. Due to the difficulty in determining the onset and offset of droughts, accurate drought forecasting approaches are required for drought risk management. Given the growing use of machine learning in the field, Wavelet-Boosting Support Vector Regression (W-BS-SVR) was proposed for drought forecasting at Langat River Basin, Malaysia. Monthly rainfall, mean temperature and evapotranspiration for years 1976 - 2015 were used to compute Standardized Precipitation Evapotranspiration Index (SPEI) in this study, producing SPEI-1, SPEI-3 and SPEI-6. The 1-month lead time SPEIs forecasting capability of W-BS-SVR model was compared with the Support Vector Regression (SVR) and Boosting-Support Vector Regression (BS-SVR) models using Root Mean Square Error (RMSE), Mean Absolute Error (MAE), coefficient of determination (R2) and Adjusted R2. The results demonstrated that W-BS-SVR provides higher accuracy for drought prediction in Langat River Basin.
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Li, Lingcheng, Dunxian She, Hui Zheng, Peirong Lin, and Zong-Liang Yang. "Elucidating Diverse Drought Characteristics from Two Meteorological Drought Indices (SPI and SPEI) in China." Journal of Hydrometeorology 21, no. 7 (July 1, 2020): 1513–30. http://dx.doi.org/10.1175/jhm-d-19-0290.1.
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AbstractThis study elucidates drought characteristics in China during 1980–2015 using two commonly used meteorological drought indices: standardized precipitation index (SPI) and standardized precipitation–evapotranspiration index (SPEI). The results show that SPEI characterizes an overall increase in drought severity, area, and frequency during 1998–2015 compared with those during 1980–97, mainly due to the increasing potential evapotranspiration. By contrast, SPI does not reveal this phenomenon since precipitation does not exhibit a significant change overall. We further identify individual drought events using the three-dimensional (i.e., longitude, latitude, and time) clustering algorithm and apply the severity–area–duration (SAD) method to examine the drought spatiotemporal dynamics. Compared to SPI, SPEI identifies a lower drought frequency but with larger total drought areas overall. Additionally, SPEI identifies a greater number of severe drought events but a smaller number of slight drought events than the SPI. Approximately 30% of SPI-detected drought grids are not identified as drought by SPEI, and 40% of SPEI-detected drought grids are not recognized as drought by SPI. Both indices can roughly capture the major drought events, but SPEI-detected drought events are overall more severe than SPI. From the SAD analysis, SPI tends to identify drought as more severe over small areas within 1 million km2 and short durations less than 2 months, whereas SPEI tends to delineate drought as more severe across expansive areas larger than 3 million km2 and periods longer than 3 months. Given the fact that potential evapotranspiration increases in a warming climate, this study suggests SPEI may be more suitable than SPI in monitoring droughts under climate change.
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Li, Jun, Zhaoli Wang, Xushu Wu, Chong-Yu Xu, Shenglian Guo, and Xiaohong Chen. "Toward Monitoring Short-Term Droughts Using a Novel Daily Scale, Standardized Antecedent Precipitation Evapotranspiration Index." Journal of Hydrometeorology 21, no. 5 (May 2020): 891–908. http://dx.doi.org/10.1175/jhm-d-19-0298.1.
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AbstractRecent events across many regions around the world have shown that short-term droughts (i.e., daily or weekly) with sudden occurrence can lead to huge losses to a wide array of environmental and societal sectors. However, the most commonly used drought indices can only identify drought at the monthly scale. Here, we introduced a daily scale drought index, that is, the standardized antecedent precipitation evapotranspiration index (SAPEI) that utilizes precipitation and potential evapotranspiration and also considers the effect of early water balance on dry/wet conditions on the current day. The robustness of SAPEI is first assessed through comparison with two typical monthly indices [Palmer drought severity index (PDSI) and standardized precipitation evapotranspiration index (SPEI)] and soil moisture, and then applied to tracking short-term droughts during 1961–2015 for the Pearl River basin in south China. It is demonstrated that SAPEI performs as well as SPEI/self-calibrating PDSI at the monthly scale but outperforms SPEI at the weekly scale. Moreover, SAPEI is capable of revealing daily drought conditions, fairly consistent with soil moisture changes. Results also show that many of the historical short-term droughts over the Pearl River basin have multiple peaks in terms of severity, affected area, and intensity. The daily scale SAPEI provides an effective way of exploring drought initiation, development, and decay, which could be conducive for decision-makers and stakeholders to make early and timely warnings.
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Tirivarombo, S., D. Osupile, and P. Eliasson. "Drought monitoring and analysis: Standardised Precipitation Evapotranspiration Index (SPEI) and Standardised Precipitation Index (SPI)." Physics and Chemistry of the Earth, Parts A/B/C 106 (August 2018): 1–10. http://dx.doi.org/10.1016/j.pce.2018.07.001.
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Beguería, Santiago, Sergio M. Vicente-Serrano, Fergus Reig, and Borja Latorre. "Standardized precipitation evapotranspiration index (SPEI) revisited: parameter fitting, evapotranspiration models, tools, datasets and drought monitoring." International Journal of Climatology 34, no. 10 (December 21, 2013): 3001–23. http://dx.doi.org/10.1002/joc.3887.
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Coll, J. R., E. Aguilar, M. Prohom, and J. Sigro. "Long-term drought variability and trends in Barcelona (1787-2014)." Cuadernos de Investigación Geográfica 42, no. 1 (June 27, 2016): 29. http://dx.doi.org/10.18172/cig.2927.
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Long-term drought variability and trends were assessed in Barcelona at annual and seasonal scale for the period 1787-2014 and sub-periods 1851-2014, 1901-2014 and 1951-2014 to identify changes in drought patterns across time. High quality and adjusted monthly temperature and precipitation series were required for this purpose. The Standardized Precipitation Index (SPI), based on precipitation, and the Standardized Precipitation Evapotranspiration Index (SPEI), based on the difference between precipitation and reference evapotranspiration (ET0), were calculated to describe temporal drought fluctuations. Therefore, major droughts and wet events were identified and an accurate analysis of drought severity, magnitude and duration were also carried out.Both drought indices provided similar results related to drought variability and trends in Barcelona across time, although the SPEI showed larger drought severity than SPI especially during the second half of the 20th century. Trends analysis revealed a significant drying trend at annual scale according to the SPEI since mid-19th century while the SPI did not show changes in drought patterns. At seasonal scale, both the SPI and SPEI found a clear drying trend only for summer (JJA) during the current period (1951-2014), although the SPEI was indicating the trend towards drier conditions for the whole period (1787-2014). Drought severity in SPEI series increased 13% during the second half of the 20th century compared with the whole period under study while drought magnitude and duration did not present significant changes in both the SPI and SPEI series. The increasing atmospheric evaporative demand associated to the large temperature rising experienced in Barcelona during the last decades could have played a substantial role in explaining the increase of drought severity and trends found in the SPEI series.
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Vicente-Serrano, Sergio M., Diego G. Miralles, Fernando Domínguez-Castro, Cesar Azorin-Molina, Ahmed El Kenawy, Tim R. McVicar, Miquel Tomás-Burguera, Santiago Beguería, Marco Maneta, and Marina Peña-Gallardo. "Global Assessment of the Standardized Evapotranspiration Deficit Index (SEDI) for Drought Analysis and Monitoring." Journal of Climate 31, no. 14 (July 2018): 5371–93. http://dx.doi.org/10.1175/jcli-d-17-0775.1.
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This article developed and implemented a new methodology for calculating the standardized evapotranspiration deficit index (SEDI) globally based on the log-logistic distribution to fit the evaporation deficit (ED), the difference between actual evapotranspiration (ETa) and atmospheric evaporative demand (AED). Our findings demonstrate that, regardless of the AED dataset used, a log-logistic distribution most optimally fitted the ED time series. As such, in many regions across the terrestrial globe, the SEDI is insensitive to the AED method used for calculation, with the exception of winter months and boreal regions. The SEDI showed significant correlations ( p < 0.05) with the standardized precipitation evapotranspiration index (SPEI) across a wide range of regions, particularly for short (<3 month) SPEI time scales. This work provides a robust approach for calculating spatially and temporally comparable SEDI estimates, regardless of the climate region and land surface conditions, and it assesses the performance and the applicability of the SEDI to quantify drought severity across varying crop and natural vegetation areas.
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da Rocha Júnior, Rodrigo Lins, Fabrício Daniel dos Santos Silva, Rafaela Lisboa Costa, Heliofábio Barros Gomes, Dirceu Luis Herdies, Vicente de Paulo Rodrigues da Silva, and Alexandre Candido Xavier. "Analysis of the Space–Temporal Trends of Wet Conditions in the Different Rainy Seasons of Brazilian Northeast by Quantile Regression and Bootstrap Test." Geosciences 9, no. 11 (October 24, 2019): 457. http://dx.doi.org/10.3390/geosciences9110457.
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Drought causes serious social and environmental problems that have great impact on the lives of thousands of people all around the world. The purpose of this research was to investigate the trends in humid conditions in the northeast of Brazil (NEB) in the highest climatic precipitation quarters, November–December–January (NDJ), February–March–April (FMA), and May–June–July (MJJ), through the standardized precipitation and evapotranspiration index (SPEI), considering an alternative statistical approach. Precipitation and potential evapotranspiration (PET) time series for the calculation of the SPEI were extracted for the 1794 NEB municipalities between 1980 and 2015 from a grid dataset with a resolution of 0.25° × 0.25° using the bilinear interpolation method. The trends and statistical significance of the SPEI were estimated by quantile regression (QR) and the bootstrap test. In NDJ, opposite trends were seen in the eastern NEB (~0.5 SPEI/decade) and in the south (~−0.6 SPEI/decade). In FMA, most of NEB presented negative trends in the 0.50 and 0.95 quantiles (~−0.3 SPEI/decade), while in MJJ, most of NEB presented positive trends in all quantiles studied (~0.4 SPEI/decade). The results are consistent with observational analyses of extreme rainfall.
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Ma, Xiongwei, Yibin Yao, and Qingzhi Zhao. "Regional GNSS-Derived SPCI: Verification and Improvement in Yunnan, China." Remote Sensing 13, no. 10 (May 14, 2021): 1918. http://dx.doi.org/10.3390/rs13101918.
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From the aspect of global drought monitoring, improving the regional drought monitoring method is becoming increasingly important for the sustainable development of regional agriculture and the economy. The standardized precipitation conversion index (SPCI) calculated by the Global Navigation Satellite System (GNSS) observation is a new means for drought monitoring that has the advantages of simple calculation and real-time monitoring. However, only SPCI with a 12-month scale has been verified on a global scale, while its capability and applicability for monitoring drought at a short time scale in regional areas have never been investigated. Therefore, this study aims to evaluate the performance of SPCI at other time scales in Yunnan, China, and propose an improved method for SPCI. The data of six GNSS stations were selected to calculate SPCI; the standardized precipitation evapotranspiration index (SPEI) and composite meteorological drought index (CI) are introduced to evaluate the SPCI at a short time scale in Yunnan Province. In addition, a modified CI (MCI) was proposed to calibrate the SPCI because of its large bias in Yunnan. Experimental results show that (1) SPCI exhibits better agreement with CI in Yunnan Province when compared to SPEI; (2) the capability of SPCI for drought monitoring is superior to that of SPEI in Yunnan; and (3) the improved SPCI is more suitable for drought monitoring in Yunnan, with a relative bias of 5.43% when compared to the MCI. These results provide a new means for regional drought monitoring in Yunnan, which is significant for dealing with drought disasters and formulating related disaster prevention and mitigation policies.
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Oikonomou, Panagiotis D., Christos A. Karavitis, and Elpida Kolokytha. "Multi-Index Drought Assessment in Europe." Proceedings 7, no. 1 (November 15, 2018): 20. http://dx.doi.org/10.3390/ecws-3-05822.
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Any attempt for the application of integrated drought management requires identifying and characterizing the event, per se. The questions of scale, boundary, and of geographic areal extent are of central concern for any efforts of drought assessment, impact identification, and thus, of drought mitigation implementation mechanisms. The use of drought indices, such as Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI), has often led to pragmatic realization of drought duration, magnitude, and spatial extension. The current effort presents the implementation of SPI and SPEI on a Pan-European scale and it is evaluated using existing precipitation and temperature data. The ENSEMBLES Observations gridded dataset (E-OBS) for precipitation, minimum temperature, and maximum temperature used covered the period 1969–2018. The two indices estimated for time steps of 6 and 12 months. The results for the application period of recurrent droughts indicate the potential that both indices offer for an improvement on drought critical areas of identification, threshold definitions and comparability, and towards contingency planning, leading to better mitigation efforts.
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Zhang, Rui, Taotao Chen, and Daocai Chi. "Global Sensitivity Analysis of the Standardized Precipitation Evapotranspiration Index at Different Time Scales in Jilin Province, China." Sustainability 12, no. 5 (February 25, 2020): 1713. http://dx.doi.org/10.3390/su12051713.
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The Standardized Precipitation Evapotranspiration Index (SPEI) has been widely applied, due to its multi-scalar features and the ability to identify different drought types. However, its sensitivity to climatic variables still remains unclear, especially at different time scales. Therefore, this study investigates the sensitivity of SPEI to average temperature (Tmean), diurnal temperature ranges (Tdelta), relative humidity (RH), solar radiation (Rs), wind speed (U2), geothermal flux (G), and precipitation (P) from 1957 to 2017 using the extended Fourier Amplitude Sensitivity Test at different time scales in Jilin Province, China. Jilin Province experienced a significant rise in Tmean, and a sharp decrease in Tdelta, Rs, and U2. P is undoubtedly the most influential factor to the SPEI among the meteorological variables, which explained 59.9%–97.9% of the total variability, especially during the main crop growing season (from May to September). While Tmean, RH, or U2 observably affect the SPEI and cannot be neglected during the nongrowing season. In terms of spatial distribution, the SPEI was mainly affected by P in the eastern region, while it was also influenced by Tmean, RH, and U2 as well in the western region. The sensitivity of the SPEI differs in time scales: P > Tmean > RH > U2 > Rs > G > Tdelta (1 to 6 month), P > U2 > RH ≈ Tmean > G > Rs > Tdelta (7 to 18 month), and P > U2 > G > Tmean > RH > Rs > Tdelta (more than 24 month time scale), respectively. The results have the potential to provide a reference for agricultural production and management in Jilin Province, China.
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Ionita, Monica, and Viorica Nagavciuc. "Changes in drought features at the European level over the last 120 years." Natural Hazards and Earth System Sciences 21, no. 5 (May 31, 2021): 1685–701. http://dx.doi.org/10.5194/nhess-21-1685-2021.
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Abstract. In this study we analyze drought features at the European level over the period 1901–2019 using three drought indices: the standardized precipitation index (SPI), the standardized precipitation evapotranspiration index (SPEI), and the self-calibrated Palmer drought severity index (scPDSI). The results based on the SPEI and scPDSI point to the fact that Central Europe (CEU) and the Mediterranean region (MED) are becoming dryer due to an increase in the potential evapotranspiration and mean air temperature, while North Europe (NEU) is becoming wetter. By contrast, the SPI drought does not reveal these changes in the drought variability, mainly due to the fact that the precipitation does not exhibit a significant change, especially over CEU. The SPEI12 indicates a significant increase both in the drought frequency and area over the last three decades for MED and CEU, while SPI12 does not capture these features. Thus, the performance of the SPI may be insufficient for drought analysis studies over regions where there is a strong warming signal. By analyzing the frequency of compound events (e.g., high temperatures and droughts), we show that the potential evapotranspiration and the mean air temperature are becoming essential components for drought occurrence over CEU and MED. This, together with the projected increase in the potential evapotranspiration under a warming climate, has significant implications concerning the future occurrence of drought events, especially for the MED and CEU regions.
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Paulo, A. A., R. D. Rosa, and L. S. Pereira. "Climate trends and behaviour of drought indices based on precipitation and evapotranspiration in Portugal." Natural Hazards and Earth System Sciences 12, no. 5 (May 16, 2012): 1481–91. http://dx.doi.org/10.5194/nhess-12-1481-2012.
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Abstract. Distinction between drought and aridity is crucial to understand water scarcity processes. Drought indices are used for drought identification and drought severity characterisation. The Standardised Precipitation Index (SPI) and the Palmer Drought Severity Index (PDSI) are the most known drought indices. In this study, they are compared with the modified PDSI for Mediterranean conditions (MedPDSI) and the Standardised Precipitation Evapotranspiration Index (SPEI). MedPDSI results from the soil water balance of an olive crop, thus real evapotranspiration is considered, while SPEI uses potential (climatic) evapotranspiration. Similarly to the SPI, SPEI can be computed at various time scales. Aiming at understanding possible impacts of climate change, prior to compare the drought indices, a trend analysis relative to precipitation and temperature in 27 weather stations of Portugal was performed for the period 1941 to 2006. A trend for temperature increase was observed for some weather stations and trends for decreasing precipitation in March and increasing in October were also observed for some locations. Comparisons of the SPI and SPEI at 9- and 12-month time scales, the PDSI and MedPDSI were performed for the same stations and period. SPI and SPEI produce similar results for the same time scales concerning drought occurrence and severity. PDSI and MedPDSI correlate well between them and the same happened for SPI and SPEI. PDSI and MedPDSI identify more severe droughts than SPI or SPEI and identify drought occurrence earlier than these indices. This behaviour is likely to be related with the fact that a water balance is performed with PDSI and MedPDSI, which better approaches the supply-demand balance.
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Bezdan, Jovana, Atila Bezdan, Boško Blagojević, Minučer Mesaroš, Borivoj Pejić, Milica Vranešević, Dragoslav Pavić, and Emilija Nikolić-Đorić. "SPEI-Based Approach to Agricultural Drought Monitoring in Vojvodina Region." Water 11, no. 7 (July 17, 2019): 1481. http://dx.doi.org/10.3390/w11071481.
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This paper presents the standardized precipitation evapotranspiration index (SPEI)-based approach to agricultural drought monitoring (ADM-SPEI approach) combining well-known methods, expert’ critical opinions, and local agro-climatic specificities. The proposed approach has been described in detail in three phases. This allows its application in any region and modification according to different agro-climatic conditions. The application of the ADM-SPEI approach has resulted in obtaining a modified SPEI for different crops (agricultural drought SPEI (AD-SPEIcrop)) in the Vojvodina region. In the first phase of the proposed approach, analytical hierarchy process (AHP) was used to obtain an experts’ group decision regarding the most suitable method for calculating evapotranspiration for a particular analyzed region. In the second phase, SPEI was modified and adjusted to the conditions in Vojvodina, where ET0 was replaced by ETc. In the validation phase, the results of the application of AD-SPEIcrop were compared to crop yields and well-known indices and evaluated by the experts’ feedback. The statistically significant correlations were achieved between AD-SPEIcrop and crop yields. The highest correlations were achieved in the months when the analyzed crops were in the developmental stages when they are most sensitive to drought. The AD-SPEIcrop better correlates to the crop yields compared to SPEI. The comparison of AD-SPEIcrop to the standardized precipitation index (SPI), SPEI, and self-calibrated Palmer drought severity index (SC-PDSI) shows that it can successfully detect dry and wet periods. The results have indicated that the proposed approach can be successfully applied, and AD-SPEIcrop has shown a good performance for agricultural drought monitoring.
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Nagy, Patrik, Martina Zeleňáková, Slávka Galas, Helena Hlavatá, and Dorota Simonová. "Identification of dry and wet 6 months’ period in eastern Slovakia using indices." MATEC Web of Conferences 310 (2020): 00047. http://dx.doi.org/10.1051/matecconf/202031000047.
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In the paper we evaluated dry and wet 6 months’ periods, which reflect changes in water resources of the country. We assessed Standardized Precipitation Index (SPI), Standardized Evapotranspiration Index (SPEI), Streamflow Drought Index (SDI), Reconnaissance Drought Index (RDI). The time period was 1960 - 2015 and the study area includes eastern Slovakia – selected water and climatic stations. The results indicate dry periods and wet periods. The results of work are presented in the table for separate evaluated indices.
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Vicente-Serrano, Sergio M., Santiago Beguería, Jorge Lorenzo-Lacruz, Jesús Julio Camarero, Juan I. López-Moreno, Cesar Azorin-Molina, Jesús Revuelto, Enrique Morán-Tejeda, and Arturo Sanchez-Lorenzo. "Performance of Drought Indices for Ecological, Agricultural, and Hydrological Applications." Earth Interactions 16, no. 10 (June 26, 2012): 1–27. http://dx.doi.org/10.1175/2012ei000434.1.
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Abstract In this study, the authors provide a global assessment of the performance of different drought indices for monitoring drought impacts on several hydrological, agricultural, and ecological response variables. For this purpose, they compare the performance of several drought indices [the standardized precipitation index (SPI); four versions of the Palmer drought severity index (PDSI); and the standardized precipitation evapotranspiration index (SPEI)] to predict changes in streamflow, soil moisture, forest growth, and crop yield. The authors found a superior capability of the SPEI and the SPI drought indices, which are calculated on different time scales than the Palmer indices to capture the drought impacts on the aforementioned hydrological, agricultural, and ecological variables. They detected small differences in the comparative performance of the SPI and the SPEI indices, but the SPEI was the drought index that best captured the responses of the assessed variables to drought in summer, the season in which more drought-related impacts are recorded and in which drought monitoring is critical. Hence, the SPEI shows improved capability to identify drought impacts as compared with the SPI. In conclusion, it seems reasonable to recommend the use of the SPEI if the responses of the variables of interest to drought are not known a priori.
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McEvoy, Daniel J., Justin L. Huntington, John T. Abatzoglou, and Laura M. Edwards. "An Evaluation of Multiscalar Drought Indices in Nevada and Eastern California." Earth Interactions 16, no. 18 (December 1, 2012): 1–18. http://dx.doi.org/10.1175/2012ei000447.1.
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Abstract Nevada and eastern California are home to some of the driest and warmest climates, most mountainous regions, and fastest growing metropolitan areas of the United States. Throughout Nevada and eastern California, snow-dominated watersheds provide most of the water supply for both human and environmental demands. Increasing demands on finite water supplies have resulted in the need to better monitor drought and its associated hydrologic and agricultural impacts. Two multiscalar drought indices, the standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI), are evaluated over Nevada and eastern California regions of the Great Basin using standardized streamflow, lake, and reservoir water surface stages to quantify wet and dry periods. Results show that both metrics are significantly correlated to surface water availability, with SPEI showing slightly higher correlations over SPI, suggesting that the inclusion of a simple term for atmospheric demand in SPEI is useful for characterizing hydrologic drought in arid regions. These results also highlight the utility of multiscalar drought indices as a proxy for summer groundwater discharge and baseflow periods.
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Tang, Han, Tong Wen, Peng Shi, Simin Qu, Lanlan Zhao, and Qiongfang Li. "Analysis of Characteristics of Hydrological and Meteorological Drought Evolution in Southwest China." Water 13, no. 13 (July 1, 2021): 1846. http://dx.doi.org/10.3390/w13131846.
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Based on the data of 82 meteorological stations and six representative hydrological stations in four provinces in Southwest China (Guizhou, Sichuan, Yunnan, Chongqing), this paper uses standardized precipitation evapotranspiration index (SPEI) and standardized runoff index (SRI) to analyze the spatial and temporal evolution characteristics of drought in the study area from 1968 to 2018. Combined with the Southwest monsoon index and historical drought data, the correlation of drought and the applicability of different drought indices were verified. The results show that: (1) SPEI-12 in Southwest China shows a downward trend from 1968 to 2018, with a linear trend rate of −0.074/10a, and SPEI-3 has a downward trend in four seasons, the maximum linear trend rate being −0.106/10a in autumn;(2) The change in SRI-12 and SRI-24 value directly reflected the decrease in SRI value, indicating that drought events are increasing in recent times, especially in the 21st century (3). Severe drought occurred in the south of Southwest China, as indicated by the increase of drought frequency in this area. The main reason for the variations in the frequency distribution of drought in Southwest China is the combined effect of the change of precipitation and evapotranspiration. (4) The correlation between hydrological drought index and disaster areas is stronger than the correlation between meteorological drought and disaster areas.
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Jincy Rose, M. A., and N. R. Chithra. "Evaluation of temporal drought variation and projection in a tropical river basin of Kerala." Journal of Water and Climate Change 11, S1 (April 20, 2020): 115–32. http://dx.doi.org/10.2166/wcc.2020.240.
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Abstract Temperature is an indispensable parameter of climate that triggers evapotranspiration and has vital importance in aggravating drought severity. This paper analyses the existence and persistence of drought conditions which are said to prevail in a tropical river basin which was once perennial. Past observed data and future climate projections of precipitation and temperature were used for this purpose. The assessment and projection of this study employ the Standardized Precipitation Evapotranspiration Index (SPEI) compared with that of the Standardized Precipitation Index (SPI). The results indicate the existence of drought in the past and the drought conditions that may persist in the future according to RCP 4.5 and 8.5 scenarios. The past drought years identified in the study were compared with the drought declared years in the state and were found to be matching. The evaluation of the future scenarios unveils the occurrence of drought in the basin ranging from mild to extreme conditions. It has been noted that the number of moderate and severe drought months has increased based on SPEI compared to SPI, indicating the importance of temperature in drought studies. The study can be considered as a plausible scientific remark helpful in risk management and application decisions.
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Páscoa, P., C. M. Gouveia, A. Russo, and R. M. Trigo. "Drought Trends in the Iberian Peninsula over the Last 112 Years." Advances in Meteorology 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/4653126.
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The Iberian Peninsula (IP) is a drought-prone area located in the Mediterranean which presents a significant tendency towards dryness during the last decades, reinforcing the need for a continuous monitoring of drought. The long-term evolution of drought in the IP is analyzed, using the Standardized Precipitation Evaporation Index (SPEI) and the Standardized Precipitation Index (SPI), for the period of 1901–2012 and for three subperiods: 1901–1937, 1938–1974, and 1975–2012. SPI and SPEI were calculated with a 12-month time scale, using data from the Climatic Research Unit (CRU) database. Trends in the drought indices, precipitation, and reference evapotranspiration (ET0) were analysed and series of drought duration, drought magnitude, time between drought events, and mean intensity of the events were computed. SPI and SPEI significant trends show areas with opposite signals in the period 1901–2012, mainly associated with precipitation trends, which are significant and positive in the northwestern region and significant and negative in the southern areas. Additionally, SPEI identified dryer conditions and an increase in the area affected by droughts, which agrees with the increase in ET0. The same spatial differences were identified in the drought duration, magnitude, mean intensity, and time between drought events.
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Ziese, M., U. Schneider, A. Meyer-Christoffer, K. Schamm, J. Vido, P. Finger, P. Bissolli, S. Pietzsch, and A. Becker. "The GPCC Drought Index – a new, combined and gridded global drought index." Earth System Science Data 6, no. 2 (August 29, 2014): 285–95. http://dx.doi.org/10.5194/essd-6-285-2014.
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Abstract. The Global Precipitation Climatology Centre Drought Index (GPCC-DI) provides estimations of water supply anomalies with respect to long-term statistics. It is a combination of the Standardized Precipitation Index with adaptations from Deutscher Wetterdienst (SPI-DWD) and the Standardized Precipitation Evapotranspiration Index (SPEI). Precipitation data were taken from the Global Precipitation Climatology Centre (GPCC) and temperature data from NOAA's Climate Prediction Center (CPC). The GPCC-DI is available with several accumulation periods of 1, 3, 6, 9, 12, 24 and 48 months for different applications. It is issued monthly starting in January 2013. Typically, it is released on the 10th day of the following month, depending on the availability of the input data. It is calculated on a regular grid with 1° spatial resolution. All accumulation periods are integrated into one netCDF file for each month. This data set is referenced by the doi:10.5676/DWD_GPCC/DI_M_100 and is available free of charge from the GPCC website ftp://ftp.dwd.de/pub/data/gpcc/html/gpcc_di_doi_download.html.
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Nedealcov, M., V. Răileanu, R. Sîrbu, and R. Cojocari. "The Use Of Standardized Indicators (SPI And SPEI) In Predicting Droughts Over The Republic Of Moldova Territory." Present Environment and Sustainable Development 9, no. 2 (October 1, 2015): 149–58. http://dx.doi.org/10.1515/pesd-2015-0032.
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Abstract The drought events frequent manifestation over the Republic of Moldova territory, in the context of climate change requires a scientific monitoring adjusted to international researchers. In recent years, internationally, the estimation of this phenomenon occurs through standardized indexes. The most used of these, being the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI). Since there is no a unified definition of drought, the World Meteorological Organization proposes to calculate the indexes, through developed calculation software. Thus, based on multi-annual data (1980-2014) a regional spatio-temporal estimation concerning drought in the Republic of Moldova was performed, thereby realizing the regional investigations framing in the international ones.
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Mishra, Nischal, Puneet Srivastava, and Sarmistha Singh. "What Do Climate Change Projections Say About Future Droughts in Alabama and Georgia?" Transactions of the ASABE 60, no. 4 (2017): 1139–51. http://dx.doi.org/10.13031/trans.11854.
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Abstract. Frequent severe droughts in recent years in the humid southeast U.S. have called for pragmatic approaches to better prepare for the consequences of droughts. This article examines how climate change will influence future droughts in Alabama and Georgia. Historic and future droughts were quantified by means of the standardized precipitation index (SPI) and standardized precipitation evapotranspiration index (SPEI), and changes in the frequency, severity, and spatial extent of droughts were examined using severity-area-frequency (SAF) curves. Precipitation and temperature data, regionally downscaled using a regional spectral model (RSM) for the southeast U.S. for the high emission scenario (A2) from three general circulation models (GCM), i.e., Hadley Centre Coupled Model Version 3 (HadCM3), Geophysical Fluid Dynamics Laboratory (GFDL), and Community Climate System Model (CCSM), from the Third Coupled Model Inter-comparison Project (CMIP3) archive were used for this study. Data from 1969 to 1999 were used for historical simulation, and 2039 to 2069 were used for future projections. The results showed that droughts similar to those in the past would be observed frequently in the future as well. The SPI and SPEI from the GFDL and HadCM3 models indicated higher frequency, severity, and spatial extent of droughts in the future. The SPI from the CCSM model did not show drastic changes in drought characteristics in either of the two states. The results of this research can be used by policymakers as a guide to determine how drought characteristics are expected to change in the future, and to develop drought mitigation policies. Keywords: Climate change, Drought, Drought indices, Severity-area-frequency curves, Standardized precipitation index, Standardized precipitation evapotranspiration index.
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Rhee, Jinyoung, and Jaepil Cho. "Future Changes in Drought Characteristics: Regional Analysis for South Korea under CMIP5 Projections." Journal of Hydrometeorology 17, no. 1 (December 31, 2015): 437–51. http://dx.doi.org/10.1175/jhm-d-15-0027.1.
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Abstract The future changes in drought characteristics were examined on a regional scale for South Korea, in northeastern Asia, using 17 bias-corrected projections from phase 5 of the Coupled Model Intercomparison Project (CMIP5) of representative concentration pathway (RCP) scenarios 4.5 and 8.5. The frequency of severe or extreme drought, based on the standardized precipitation index (SPI) and standardized precipitation evapotranspiration index (SPEI), with time scales of 1, 3, and 12 months (i.e., SPI1, SPI3, SPI12, SPEI1, SPEI3, and SPEI12), was considered, as well as the average duration based on SPEI1. A multimodel ensemble (MME) was produced using selected models, and future changes were investigated in terms of both drought frequency and the average duration for the entire area and four river basins. The changes in drought frequency largely depend on the selection of a drought index, rather than climate projection scenarios. SPEI3 mostly projected future increases in drought frequency, while SPI3 showed varied projections. SPI12 projected decreases in drought frequency for both scenarios in the study area, while differences between river basins were observed for SPEI12. Increases in the average duration of droughts were projected based on SPEI1, indicating an increase in persistent short-term droughts in the future. The results emphasize the importance of regional- and subregional-scale analysis in northeastern Asia. The findings of the study provide valuable information that can be used for drought-related decision-making, which could not be obtained from studies on a global spatial scale.
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Ziese, M., U. Schneider, A. Meyer-Christoffer, K. Schamm, J. Vido, P. Finger, P. Bissolli, S. Pietzsch, and A. Becker. "GPCC Drought Index – a new, combined, and gridded global drought index." Earth System Science Data Discussions 7, no. 1 (April 29, 2014): 243–70. http://dx.doi.org/10.5194/essdd-7-243-2014.
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Abstract. The Global Precipitation Climatology Centre Drought Index (GPCC-DI) provides estimations of precipitation anomalies with respect to long term statistics. It is a combination of the Standardized Precipitation Index with adaptations from Deutscher Wetterdienst (SPI-DWD) and the Standardized Precipitation Evapotranspiration Index (SPEI). Precipitation data were taken from the Global Precipitation Climatology Centre (GPCC) and temperature data from NOAA's Climate Prediction Center (CPC). The GPCC-DI is available with several averaging periods of 1, 3, 6, 9, 12, 24 and 48 months for different applications. Since spring 2013, the GPCC-DI is calculated operationally and available back to January 2013. Typically it is released at the 10th day of the following month, depending on the availability of the input data. It is calculated on a~regular grid with 1° spatial resolution. All averaging periods are integrated into one netCDF-file for each month. This dataset can be referenced by the DOI:10.5676/DWD_GPCC/DI_M_100 and is available free of charge from the GPCC website ftp://ftp.dwd.de/pub/data/gpcc/html/gpcc_di_doi_download.html.
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Mulualem, Getachew Mehabie, and Yuei-An Liou. "Application of Artificial Neural Networks in Forecasting a Standardized Precipitation Evapotranspiration Index for the Upper Blue Nile Basin." Water 12, no. 3 (February 27, 2020): 643. http://dx.doi.org/10.3390/w12030643.
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The occurrence frequency of drought has intensified with the unprecedented effect of global warming. Knowledge about the spatiotemporal distributions of droughts and their trends is crucial for risk management and developing mitigation strategies. In this study, we developed seven artificial neural network (ANN) predictive models incorporating hydro-meteorological, climate, sea surface temperatures, and topographic attributes to forecast the standardized precipitation evapotranspiration index (SPEI) for seven stations in the Upper Blue Nile basin (UBN) of Ethiopia from 1986 to 2015. The main aim was to analyze the sensitivity of drought-trigger input parameters and to measure their predictive ability by comparing the predicted values with the observed values. Statistical comparisons of the different models showed that accurate results in predicting SPEI values could be achieved by including large-scale climate indices. Furthermore, it was found that the coefficient of determination and the root-mean-square error of the best architecture ranged from 0.820 to 0.949 and 0.263 to 0.428, respectively. In terms of statistical achievement, we concluded that ANNs offer an alternative framework for forecasting the SPEI drought index.
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Abatzoglou, John T., Renaud Barbero, Jacob W. Wolf, and Zachary A. Holden. "Tracking Interannual Streamflow Variability with Drought Indices in the U.S. Pacific Northwest." Journal of Hydrometeorology 15, no. 5 (September 25, 2014): 1900–1912. http://dx.doi.org/10.1175/jhm-d-13-0167.1.
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Abstract Drought indices are often used for monitoring interannual variability in macroscale hydrology. However, the diversity of drought indices raises several issues: 1) which indices perform best and where; 2) does the incorporation of potential evapotranspiration (PET) in indices strengthen relationships, and how sensitive is the choice of PET methods to such results; 3) what additional value is added by using higher-spatial-resolution gridded climate layers; and 4) how have observed relationships changed through time. Standardized precipitation index, standardized precipitation evapotranspiration index (SPEI), Palmer drought severity index, and water balance runoff (WBR) model output were correlated to water-year runoff for 21 unregulated drainage basins in the Pacific Northwest of the United States. SPEI and WBR with time scales encompassing the primary precipitation season maximized the explained variance in water-year runoff in most basins. Slightly stronger correlations were found using PET estimates from the Penman–Monteith method over the Thornthwaite method, particularly for time periods that incorporated the spring and summer months in basins that receive appreciable precipitation during the growing season. Indices computed using high-resolution climate surfaces explained over 10% more variability than metrics derived from coarser-resolution datasets. Increased correlation in the latter half of the study period was partially attributable to increased streamflow variability in recent decades as well as to improved climate data quality across the interior mountain watersheds.
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Peña-Gallardo, Marina, Sergio Martín Vicente-Serrano, Fernando Domínguez-Castro, and Santiago Beguería. "The impact of drought on the productivity of two rainfed crops in Spain." Natural Hazards and Earth System Sciences 19, no. 6 (June 19, 2019): 1215–34. http://dx.doi.org/10.5194/nhess-19-1215-2019.
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Abstract. Drought events are of great importance in most Mediterranean climate regions because of the diverse and costly impacts they have in various economic sectors and on the environment. The effects of this natural hazard on rainfed crops are particularly evident. In this study the impacts of drought on two representative rainfed crops in Spain (wheat and barley) were assessed. As the agriculture sector is vulnerable to climate, it is especially important to identify the most appropriate tools for monitoring the impact of the weather on crops, and particularly the impact of drought. Drought indices are the most effective tool for that purpose. Various drought indices have been used to assess the influence of drought on crop yields in Spain, including the Standardized Precipitation Evapotranspiration Index (SPEI), the Standardized Precipitation Index (SPI), the Palmer drought indices (Palmer Drought Severity Index, PDSI; Palmer Z Index, Z Index; Palmer Hydrological Drought Index, PHDI; Palmer Modified Drought Index, PMDI), and the Standardized Palmer Drought Index (SPDI). Two sets of crop yield data at different spatial scales and temporal periods were used in the analysis. The results showed that drought indices calculated at different timescales (SPI, SPEI) most closely correlated with crop yield. The results also suggested that different patterns of yield response to drought occurred depending on the region, period of the year, and the drought timescale. The differing responses across the country were related to season and the magnitude of various climate variables.
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Oertel, Melanie, Francisco Meza, Jorge Gironás, Christopher A. Scott, Facundo Rojas, and Nicolás Pineda-Pablos. "Drought Propagation in Semi-Arid River Basins in Latin America: Lessons from Mexico to the Southern Cone." Water 10, no. 11 (November 2, 2018): 1564. http://dx.doi.org/10.3390/w10111564.
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Detecting droughts as early as possible is important in avoiding negative impacts on economy, society, and environment. To improve drought monitoring, we studied drought propagation (i.e., the temporal manifestation of a precipitation deficit on soil moisture and streamflow). We used the Standardized Precipitation Evapotranspiration Index (SPEI), Standardized Streamflow Index (SSI), and Standardized Soil Moisture Index (SSMI) in three drought-prone regions: Sonora (Mexico), Maipo (Chile), and Mendoza-Tunuyán (Argentina) to study their temporal interdependence. For this evaluation we use precipitation, temperature, and streamflow data from gauges that are managed by governmental institutions, and satellite-based soil moisture from the ESA CCI SM v03.3 combined data set. Results confirm that effective drought monitoring should be carried out (1) at river-basin scale, (2) including several variables, and (3) considering hydro-meteorological processes from outside its boundaries.
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Li, Yi, Chunyan Chen, and Changfeng Sun. "Drought severity and change in Xinjiang, China, over 1961–2013." Hydrology Research 48, no. 5 (September 30, 2016): 1343–62. http://dx.doi.org/10.2166/nh.2016.026.
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Monthly climatic data from 53 sites across Xinjiang, China, were used to compare drought severity from the widely accepted Standardized Precipitation Index (SPI) with the recently proposed Standardized Precipitation Evapotranspiration Index (SPEI), as well as trends in the data from 1961 to 2013. Monthly Thornthwaite based (ETo.TW) and Penman-Monteith based reference evapotranspiration (ETo.PM) were computed and subsequently used to estimate SPEITW and SPEIPM, respectively. The indices' sensitivity, spatiotemporal distributions and trends were analyzed. The results showed that the TW equation underestimated ETo, which affected the accuracy of the SPEI estimation. Greater consistency was found between SPI and SPEIPM than between SPI and SPEITW at different timescales. SPI and SPEIPM were sensitive to precipitation, but SPEITW and SPEIPM were insensitive to ETo. The scope of spatial SPEIPM was wider than that of SPI at the same timescale. Obvious differences in SPI, SPEITW and SPEIPM existed between northern and southern Xinjiang. SPEIPM was a better indicator of global warming than SPI. Both SPI and SPEIPM had increasing trends, which contradict previously reported trends in global drought. In conclusion, the decrease in drought severity observed over the last 53 years may indicate some relief in the water utilization crisis in Xinjiang, China.
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Chen, Huopo, and Jianqi Sun. "Changes in Drought Characteristics over China Using the Standardized Precipitation Evapotranspiration Index." Journal of Climate 28, no. 13 (July 1, 2015): 5430–47. http://dx.doi.org/10.1175/jcli-d-14-00707.1.
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Abstract The standardized precipitation evapotranspiration index (SPEI) is computed and compared in China using reference evapotranspiration calculated using the Thornthwaite (TH) approach and the Penman–Monteith (PM) equation. The analysis reveals that SPEI_PM outperforms the SPEI_TH with regard to drought monitoring during the period 1961–2012 over China, especially in arid regions of China. Furthermore, the SPEI_PM also performs better with regard to observed variations in soil moisture and streamflow in China. Thus, changes in drought characteristics over China are detected on the basis of variations in the SPEI_PM. The results indicate that droughts over China exhibit pronounced decadal variations over the past 50 yr, with more frequent and severe droughts occurring before the 1980s and in the 2000s compared with the 1980s and 1990s. Since the late 1990s, droughts have become more frequent and severe across China, especially in some regions of northern China. Concurrently, consecutive drought events have also increased across China. This suggests that dry conditions in China have been enhanced in recent years. Further analyses illustrate that the temperature and precipitation anomalies exhibit different roles in detecting droughts across China, which is primarily due to the magnitude of their variations and different climate variability. Considering temperature and precipitation perturbations, droughts exhibit relatively larger responses to temperature fluctuations in northern China and relatively larger responses to precipitation anomalies in southern China.
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Liu, Shaohua, Denghua Yan, Hao Wang, Chuanzhe Li, Baisha Weng, and Tianling Qin. "Standardized Water Budget Index and Validation in Drought Estimation of Haihe River Basin, North China." Advances in Meteorology 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/9159532.
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The physical-based drought indices such as the self-calibrated Palmer Drought Severity Index (sc-PDSI) with the fixed time scale is inadequate for the multiscalar drought assessment, and the multiscalar drought indices including Standardized Precipitation Index (SPI), Reconnaissance Drought Index (RDI), and Standardized Precipitation Evapotranspiration Index (SPEI) based on the meteorological factors are lack of physical mechanism and cannot depict the actual water budget. To fill this gap, the Standardized Water Budget Index (SWBI) is constructed based on the difference between areal precipitation and actual evapotranspiration (AET), which can describe the actual water budget but also assess the drought at multiple time scales. Then, sc-PDSI was taken as the reference drought index to compare with multiscalar drought indices at different time scale in Haihe River basin. The result shows that SWBI correlates better with sc-PDSI and the RMSE of SWBI is less than other multiscalar drought indices. In addition, all of drought indices show a decreasing trend in Haihe River Basin, possibly due to the decreasing precipitation from 1961 to 2010. The decreasing trends of SWBI were significant and consistent at all the time scales, while the decreasing trends of other multiscalar drought indices are insignificant at time scale less than 3 months.
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Vicente-Serrano, S. M., S. Beguería, J. I. López-Moreno, M. Angulo, and A. El Kenawy. "A New Global 0.5° Gridded Dataset (1901–2006) of a Multiscalar Drought Index: Comparison with Current Drought Index Datasets Based on the Palmer Drought Severity Index." Journal of Hydrometeorology 11, no. 4 (August 1, 2010): 1033–43. http://dx.doi.org/10.1175/2010jhm1224.1.
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Abstract A monthly global dataset of a multiscalar drought index is presented and compared in terms of spatial and temporal variability with the existing continental and global drought datasets based on the Palmer drought severity index (PDSI). The presented dataset is based on the standardized precipitation evapotranspiration index (SPEI). The index was obtained using the Climatic Research Unit (CRU) TS3.0 dataset at a spatial resolution of 0.5°. The advantages of the new dataset are that (i) it improves the spatial resolution of the unique global drought dataset at a global scale; (ii) it is spatially and temporally comparable to other datasets, given the probabilistic nature of the SPEI; and, in particular, (iii) it enables the identification of various drought types, given the multiscalar character of the SPEI. The dataset is freely available on the Web page of the Spanish National Research Council (CSIC) in three different formats [network Common Data Form (netCDF), binary raster, and plain text].
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Feizi, Mehdi, Najmeh Heidarzadeh Janatabadi, and Ahmad Saradari Torshizi. "Rainfall and social disputes in Iran." Water Policy 21, no. 4 (May 22, 2019): 880–93. http://dx.doi.org/10.2166/wp.2019.101.
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Abstract Water crisis and, particularly, drop in rainfall in Iran are not only an environmental matter but also a security issue. This paper tries to draw attention to the substantial social consequences of climate change in Iran and particularly addresses whether precipitation scarcity from 2007 to 2014 has a conflict-making effect in the province of Iran using the system GMM model. We show that rainfall shortage and the Standardized Precipitation Evapotranspiration Index (SPEI), as an index of drought, could stimulate the propensity for individuals to engage in disruptive activities in provinces of Iran.
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Zhu, Ye, Yi Liu, Xieyao Ma, Liliang Ren, and Vijay Singh. "Drought Analysis in the Yellow River Basin Based on a Short-Scalar Palmer Drought Severity Index." Water 10, no. 11 (October 26, 2018): 1526. http://dx.doi.org/10.3390/w10111526.
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Focusing on the shortages of moisture estimation and time scale in the self-calibrating Palmer drought severity index (scPDSI), this study proposed a new Palmer variant by introducing the Variable Infiltration Capacity (VIC) model in hydrologic accounting module, and modifying the standardization process to make the index capable for monitoring droughts at short time scales. The performance of the newly generated index was evaluated over the Yellow River Basin (YRB) during 1961–2012. For time scale verification, the standardized precipitation index (SPI), and standardized precipitation evapotranspiration index (SPEI) at a 3-month time scale were employed. Results show that the new Palmer variant is highly correlated with SPI and SPEI, combined with a more stable behavior in drought frequency than original scPDSI. For drought trend detection, this new index is more inclined to reflect comprehensive moisture conditions and reveals a different spatial pattern from SPI and SPEI in winter. Besides, two remote sensing products of soil moisture and vegetation were also employed for comparison. Given their general consistent behaviors in monitoring the spatiotemporal evolution of the 2000 drought, it is suggested that the new Palmer variant is a good indicator for monitoring soil moisture variation and the dynamics of vegetation growth.
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Peña-Gallardo, Marina, Sergio Vicente-Serrano, J. Camarero, Antonio Gazol, Raúl Sánchez-Salguero, Fernando Domínguez-Castro, Ahmed El Kenawy, et al. "Drought Sensitiveness on Forest Growth in Peninsular Spain and the Balearic Islands." Forests 9, no. 9 (August 30, 2018): 524. http://dx.doi.org/10.3390/f9090524.
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Drought is one of the key natural hazards impacting net primary production and tree growth in forest ecosystems. Nonetheless, tree species show different responses to drought events, which make it difficult to adopt fixed tools for monitoring drought impacts under contrasting environmental and climatic conditions. In this study, we assess the response of forest growth and a satellite proxy of the net primary production (NPP) to drought in peninsular Spain and the Balearic Islands, a region characterized by complex climatological, topographical, and environmental characteristics. Herein, we employed three different indicators based on in situ measurements and satellite image-derived vegetation information (i.e., tree-ring width, maximum annual greenness, and an indicator of NPP). We used seven different climate drought indices to assess drought impacts on the tree variables analyzed. The selected drought indices include four versions of the Palmer Drought Severity Index (PDSI, Palmer Hydrological Drought Index (PHDI), Z-index, and Palmer Modified Drought Index (PMDI)) and three multi-scalar indices (Standardized Precipitation Evapotranspiration Index (SPEI), Standardized Precipitation Index (SPI), and Standardized Precipitation Drought Index (SPDI)). Our results suggest that—irrespective of drought index and tree species—tree-ring width shows a stronger response to interannual variability of drought, compared to the greenness and the NPP. In comparison to other drought indices (e.g., PDSI), and our results demonstrate that multi-scalar drought indices (e.g., SPI, SPEI) are more advantageous in monitoring drought impacts on tree-ring growth, maximum greenness, and NPP. This finding suggests that multi-scalar indices are more appropriate for monitoring and modelling forest drought in peninsular Spain and the Balearic Islands.
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Drumond, Anita, Milica Stojanovic, Raquel Nieto, Luis Gimeno, Margarida L. R. Liberato, Theotonio Pauliquevis, Marina Oliveira, and Tercio Ambrizzi. "Dry and Wet Climate Periods over Eastern South America: Identification and Characterization through the SPEI Index." Atmosphere 12, no. 2 (January 26, 2021): 155. http://dx.doi.org/10.3390/atmos12020155.
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A large part of the population and the economic activities of South America are located in eastern regions of the continent, where extreme climate events are a recurrent phenomenon. This study identifies and characterizes the dry and wet climate periods at domain-scale occurring over the eastern South America (ESA) during 1980–2018 through the multi-scalar Standardized Precipitation–Evapotranspiration Index (SPEI). For this study, the spatial extent of ESA was defined according to a Lagrangian approach for moisture analysis. It consists of the major continental sink of the moisture transported from the South Atlantic Ocean throughout the year, comprising the Amazonia, central Brazil, and the southeastern continental areas. The SPEI for 1, 3, 6, and 12 months of accumulation was calculated using monthly precipitation and potential evapotranspiration time series averaged on ESA. The analysis of the climate periods followed two different approaches: classification of the monthly SPEI values as mild, moderate, severe, and extreme; the computation of the events and their respective parameters (duration, severity, intensity, and peak). The results indicate that wet periods prevailed in the 1990s and 2000s, while dry conditions predominated in the 2010s, when the longest and more severe dry events have been identified at the four scales.
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Pei, Zhifang, Shibo Fang, Lei Wang, and Wunian Yang. "Comparative Analysis of Drought Indicated by the SPI and SPEI at Various Timescales in Inner Mongolia, China." Water 12, no. 7 (July 6, 2020): 1925. http://dx.doi.org/10.3390/w12071925.
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The global climate is noticeably warming, and drought occurs frequently. Therefore, choosing a suitable index for drought monitoring is particularly important. The standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI) are commonly used indicators in drought monitoring. The SPEI takes temperature into account, but the SPI does not. In the context of global warming, what are their differences and applicability in regional drought monitoring? In this study, after calculating the SPI and SPEI at 1-, 3-, 6-, and 12-month timescales at 102 meteorological stations in Inner Mongolia from 1981 to 2018, we compared and analyzed the performances of the SPI and SPEI in drought monitoring from temporal and spatial variations, and the consistency and applicability of the SPI and SPEI were also discussed. The results showed that (1) with increasing timescale, the temporal variations in the SPI and SPEI were increasingly consistent, but there were still slight differences in the fluctuation value and continuity; (2) due to the difference in time series, the drought characteristics identified by the SPI and SPEI were quite different in space at various timescales, and with the increase in timescale, the spatial distributions of the drought trends in Inner Mongolia were basically consistent, except in Alxa; (3) at the shortest timescale, the difference between the SPI and SPEI was the largest, and the drought reflected by the SPI and SPEI may be consistent at long timescales; and (4) compared with typical drought events and vegetation indexes, the SPEI may be more suitable than the SPI for drought monitoring in Inner Mongolia. It should be noted that the adaptability of the SPI and SPEI may be different in different periods and regions, which remains to be analyzed in the future.
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Peng, Jian, Simon Dadson, Feyera Hirpa, Ellen Dyer, Thomas Lees, Diego G. Miralles, Sergio M. Vicente-Serrano, and Chris Funk. "A pan-African high-resolution drought index dataset." Earth System Science Data 12, no. 1 (March 31, 2020): 753–69. http://dx.doi.org/10.5194/essd-12-753-2020.
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Abstract. Droughts in Africa cause severe problems, such as crop failure, food shortages, famine, epidemics and even mass migration. To minimize the effects of drought on water and food security on Africa, a high-resolution drought dataset is essential to establish robust drought hazard probabilities and to assess drought vulnerability considering a multi- and cross-sectional perspective that includes crops, hydrological systems, rangeland and environmental systems. Such assessments are essential for policymakers, their advisors and other stakeholders to respond to the pressing humanitarian issues caused by these environmental hazards. In this study, a high spatial resolution Standardized Precipitation-Evapotranspiration Index (SPEI) drought dataset is presented to support these assessments. We compute historical SPEI data based on Climate Hazards group InfraRed Precipitation with Station data (CHIRPS) precipitation estimates and Global Land Evaporation Amsterdam Model (GLEAM) potential evaporation estimates. The high-resolution SPEI dataset (SPEI-HR) presented here spans from 1981 to 2016 (36 years) with 5 km spatial resolution over the whole of Africa. To facilitate the diagnosis of droughts of different durations, accumulation periods from 1 to 48 months are provided. The quality of the resulting dataset was compared with coarse-resolution SPEI based on Climatic Research Unit (CRU) Time Series (TS) datasets, Normalized Difference Vegetation Index (NDVI) calculated from the Global Inventory Monitoring and Modeling System (GIMMS) project and root zone soil moisture modelled by GLEAM. Agreement found between coarse-resolution SPEI from CRU TS (SPEI-CRU) and the developed SPEI-HR provides confidence in the estimation of temporal and spatial variability of droughts in Africa with SPEI-HR. In addition, agreement of SPEI-HR versus NDVI and root zone soil moisture – with an average correlation coefficient (R) of 0.54 and 0.77, respectively – further implies that SPEI-HR can provide valuable information for the study of drought-related processes and societal impacts at sub-basin and district scales in Africa. The dataset is archived in Centre for Environmental Data Analysis (CEDA) via the following link: https://doi.org/10.5285/bbdfd09a04304158b366777eba0d2aeb (Peng et al., 2019a).