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Cynthia Barnett's Rain begins four billion years ago with the torrents that filled the oceans, and builds to the storms of climate change. It weaves together science--the true shape of a raindrop, the mysteries of frog and fish rains--with the human story of our ambition to control rain, from ancient rain dances to the 2,203 miles of levees that attempt to straitjacket the Mississippi River. As climate change upends rai nfall patterns and unleashes increasingly severe storms and drought, Barnett shows rain to be a unifying force in a fractured world.

The drought is a prominent disaster the world is facing currently. The drought identification, its characterization, and monitoring are, thus, very important to mitigate this calamity. Many drought indices have been developed for this purpose in the past; however, their evaluation is necessary to select the best suited drought index for the specific area. This study aims to analyze the meteorological drought risk across the Raigarh district of Chhattisgarh state by evaluating five popular drought indices, namely, Reconnaissance drought index (RDI) rainfall anomaly index, standardized precipitation evapotranspiration index (SPEI), standardized precipitation index (SPI), and standardized anomaly index (SAI) considering all the tehsils of the district and proposes the methodology to select the best suited index for the region. The methodology has been selected in such a manner that it deals with all aspects of meteorological drought and the most suitable drought index for the region can be identified by comparing the drought indices based on the actual drought occurrence in the region which are identified by different agencies. These drought indices were computed for different assessment periods of 1, 3, 6, 9, and 12 months using the historical precipitation and temperature data derived from (NASA-POWER) for the period 1981–2021. The variation in severity in terms of extreme, severe, and moderate drought events has been observed with these drought indices in the district. Maximum correlation is observed between RAI and SAI across all assessment periods. Further, the SPI is seen to have fairly good agreement with all other drought indices and it rises with increasing assessment periods. Modified Mann–Kendall test shows a significant positive trend for all drought indices (except SPEI across all assessment periods, RDI-1 and RDI-3) across all assessment periods. The SPI performs exceptionally well in capturing the actual drought conditions reported by different agencies in the Raigarh region among all other indices considered in this study. It is also observed that although SPEI which comes out to be the second most suitable index for drought identification in the study region, it was not able to capture the drought events before 1990. However, SPEI identified most of the drought years post 1990 which shows the prevalent effect of temperature on the formulation of index driven by heavy industrialization in the region post 1990. Overall results suggest that the SPI is the best-suited meteorological drought index for the Raigarh region.

In the literature, numerous papers report comparative analyses of drought indices. In these types of studies, the similarity between drought indices is usually evaluated using the Pearson correlation coefficient, r, calculated between corresponding severity time series. However, it is well known that the correlation does not describe the strength of agreement between two variables. Two drought indices can exhibit a high degree of correlation but can, at the same time, disagree substantially, for example, if one index is consistently higher than the other. From an operational point of view, two indices can be considered in agreement when they indicate the same severity category for a given period (e.g. moderate drought). In this work, we compared six meteorological drought indices based on both correlation analysis and Cohen's Kappa test. This test is typically used in medical or social sciences to obtain a quantitative assessment of the degree of agreement between different methods or analysts. The indices considered are five timescale-dependent indices, i.e. the Percent of Normal Index, the Deciles Index, the Percentile Index, the Rainfall Anomaly Index, and the Standardised Precipitation Index, computed at the 1-, 3-, and 6-month timescales, and the Effective Drought Index, a relatively new index, which has a self-defined timescale. The indices were calculated for 15 stations in the Abruzzo region (central Italy) during 1951–2018. We found that the strength of agreement depends on both the criteria of drought severity classification and the different indices' calculation method. The Cohen's Kappa test indicates a prevailing moderate or fair agreement among the indices considered, despite the generally very high correlation between the corresponding severity times series. The results demonstrate that the Cohen's Kappa test is more effective than the correlation analysis in discriminating the actual strength of agreement/disagreement between drought indices.

This study investigated the climatology, trends, and variability of precipitation, reference evapotranspiration (ET o ), and climatic water balance (CWB) in Ethiopia and its 12 basins from 1980 to 2021. Mean annual rainfall was 773 mm, with significant regional variations, while the mean annual ET o was 958 mm. Kiremt (June–September) received the highest rainfall (393 mm), and Belg (February–May) exhibited high ET o . The annual mean CWB was −185 mm, with only four basins showing a positive CWB. Spatially, western Ethiopia experienced higher rainfall, while the northeast had higher ET o . Temporally, both annual rainfall (2.01 mm/year) and ET o (0.40 mm/year) significantly increased nationally, with regional variations. Rainfall variability was highest in the Bega (October–January) season (CV = 45.5%) and lowest in Kiremt (CV = 21.9%). CWB showed the highest variability. Years with moderate to extreme dry and wet conditions were identified through standardized rainfall anomaly analysis. These hydroclimatic patterns and their changes have significant implications for forestry development in Ethiopia, necessitating region‐specific strategies. Positive rainfall trends in western and southern basins offer opportunities for faster tree growth, while decreasing rainfall and negative CWB in the northeast pose challenges requiring drought‐tolerant species and water conservation. The increasing ET o and high interannual rainfall variability further emphasize the need for careful species selection and resilient forestry management practices across Ethiopia.

Understanding the long-term rainfall trends and characteristics of meteorological drought resulting from scanty rainfall, under the influence of changing climate, is vital in addressing the challenges associated with the management of water resources. An attempt has been made to analyze the changes in long-term rainfall trends and meteorological drought characteristics in agro-climatic zones of two different regions, i.e., Tamil Nadu and Rajasthan, India. A 52-year daily gridded precipitation dataset (0.25° × 0.25°) for the period of 1969 to 2020 has been obtained from the India Meteorological Department (IMD) to analyze region-wise agro-climatic rainfall variability and drought characteristics. In addition, IMD grids of both regions are divided into three zones based on the classification of agro-climatic zones (ACZs) of India. The ACZs-wise precipitation irregularity has been evaluated using the Rainfall Anomaly Index (RAI). The Standardized Precipitation Index (SPI) was also performed at different time scales (three, six, twelve, and twenty-four months) to identify the meteorological droughts. Further, the run theory was applied to characterize drought assessment for both regions. SPI results showed that in Tamil Nadu, the East coast plains and hills region (zone 3 ECH) experienced more frequent but less severe and short-lived droughts, while the West coast plains and hills region (zone 1 WCG) experienced less frequent but more severe and long-lasting droughts, whereas in Rajasthan, the Western Dry Region (zone 3 WDR) experienced more frequent but less severe droughts, while the Trans Gangetic Plains (zone 1 TGP) experienced less but more severe and long-lasting droughts. Findings revealed that the regional topography and moisture availability perform a major role in regional precipitation variability. A comparative evaluation of drought characteristics in different climatic regions using agro-climatic zones provides valuable information to planners for adopting management strategies to easily tackle drought conditions.

In this study, the properties and related anomalies in sea surface wind and rainfall associated with marine heatwaves (MHWs) in the northern South China Sea (SCS) were investigated. The intensity and frequency (duration) of MHWs are high (short) along the coast and decrease (increase) when moving toward the open sea. On the continental shelf of the northern SCS, the wind anomalies associated with MHWs move in a northeastward direction in seasons other than summer. In the summer, MHW-induced wind anomalies were found to be statistically insignificant. In response to MHWs, there is a notable negative rainfall anomaly observed during the spring and summer, whereas a positive anomaly is observed in the fall. In the winter, the MHW-induced rainfall anomalies were deemed insignificant. The presence of an El Niño event can delay the influence of MHWs on rainfall anomalies and attenuate the amplitude of MHW-induced sea surface wind anomalies.

Impacts of Climate Change on Rainfall Extremes and Urban Drainage Systems provides a state-of-the-art overview of existing methodologies and relevant results related to the assessment of the climate change impacts on urban rainfall extremes as well as on urban hydrology and hydraulics. This overview focuses mainly on several difficulties and limitations regarding the current methods and discusses various issues and challenges facing the research community in dealing with the climate change impact assessment and adaptation for urban drainage infrastructure design and management

The middle and lower reaches of the Yangtze River basin (MLRYB) are prone to flooding because their orientation is parallel to the East Asian summer monsoon rain belt. Since the East Asian summer monsoon presents pronounced intraseasonal variability, the subseasonal prediction of summer precipitation anomalies in the MLRYB region is an imperative demand nationwide. Based on rotated empirical orthogonal function analysis, 48 stations over the MLRYB with coherent intraseasonal (10–80-day) rainfall variability are identified. Power spectrum analysis of the MLRYB rainfall index, defined as the 48-station-averaged intraseasonal rainfall anomaly, presents two dominant modes with periods of 20–30 days and 40–60 days, respectively. Therefore, the intraseasonal (10–80-day) rainfall variability is divided into 10–30-day and 30–80-day components, and their predictability sources are detected separately. Spatial-temporal projection models (STPM) are then conducted using these predictability sources. The forecast skill during the period 2003–2010 indicates that the STPM is able to capture the 30–80-day rainfall anomalies 5–30 days in advance, but unable to reproduce the 10–30-day rainfall anomalies over MLRYB. The year-to-year fluctuation in forecast skill might be related to the tropical Pacific sea surface temperature anomalies. High forecasting skill tends to appear after a strong El Niño or strong La Niña when the summer seasonal mean rainfall over the MLRYB is enhanced, whereas low skill is apparent after neutral conditions or a weak La Niña when the MLRYB summer seasonal mean rainfall is weakened. Given the feasibility of STPM, the application of this technique is recommended in the real-time operational forecasting of MLRYB rainfall anomalies during the summer flooding season.

Analysis of temporal dynamics of climatic parameters is indispensable for advancing the “Sustainable Development Goals (SDGs)-11 and 13”. This study aims to assess the trend of temperature and rainfall in Kolkata District using CRU (Climate Research Unit) data from 1901 to 2019. Statistical methods such as anomaly index, CV (“coefficient of variation”), and PCI (“Precipitation Concentration Index”) were employed along with ITA (Innovative trend analysis) techniques, Mann-Kendall test, and Spearman’s Rho tools. These measures are widely used in climate and environmental research to recognize the trend of climate change. The Mann-Kendall and Spearman’s Rho tools both reveal that the seasonal (summer and winter) and yearly temperatures are rising significantly (P

The 2020 Meiyu season has received extensive attention due to its record-breaking rainfall in the Yangtze–River Huai Basin (YHRB) region of China. Although its rainfall features have been well studied on various time scales, the sub-hourly/hourly rainfall features are unknown. In this study, a wavelet analysis was applied to 1 min rainfall data from 480 national rain gauges across the YHRB, and hourly synoptic patterns during the Meiyu season were grouped using an obliquely rotated principal component analysis in T-mode (PCT). The results suggest that variances on the sub-hourly and hourly scales contributed 63.4% of the 2020 Meiyu rainfall. The hourly synoptic variations in the Meiyu season can be categorized into three major patterns: weak synoptic forcing (P1), a convergence line (P2), and a vortex (P3). The rainfalls under P1 were spatially dispersed over the YHRB and on the shortest time scale, with a 70.4% variance from sub-hourly to hourly rainfalls. P2 had a peak wavelet variance around 30 min–1 h, with rainfalls concentrated to the south of the convergent line. The rainfalls under P3 were locally distributed with a longer duration of around 1–4 h. Compared with the climate mean, hourly rainfall frequencies are indispensable to understanding the 2020 accumulated Meiyu rainfall anomaly. This research highlights the dominant role of synoptic patterns on the temporal and spatial features of the Meiyu rainfall.