International Journal of Climatology最新文献

{"title":"Spatiotemporal Changes and Climate Driving Factors of Compound Precipitation-Temperature Extreme Events Across Global Land Areas","authors":"Ruting Yang,&nbsp;Silong Zhang,&nbsp;Xiongpeng Tang,&nbsp;Chao Gao,&nbsp;Haibin Zhang,&nbsp;Xin Yin,&nbsp;Yanli Liu","doi":"10.1002/joc.70491","DOIUrl":"https://doi.org/10.1002/joc.70491","url":null,"abstract":"<p>Compound climate extremes, such as concurrent precipitation and temperature extremes, cause significant impacts on socioeconomics and ecosystems. Recent studies have made substantial progress in the specific type of compound extremes; however, characteristics of different types of compound precipitation and temperature extremes across the globe and their driving mechanisms remain limited understood. This study investigated characteristics of compound extremes including dry-warm (DW), wet-warm (WW), dry-cold (DC), and wet-cold (WC) combinations in annual, JJA (June, July, and August), and DJF (December, January, and February) occurrences during 1901–2024 across global land areas and their relationships with climate variability modes. Results indicated that the spatial distribution of the frequency of DW (WW) showed a similar pattern to that of WC (DC). The overall frequency of compound warm-related (cold-related) extremes successively increased (increased and then decreased) from the period 1901–1941 to the period 1983–2024. The spatial extent of compound warm-related (cold-related) extremes presented an increasing (decreasing) trend in all the continents over the past 124 years. The areas with positive (negative) precipitation-temperature correlation showed high frequency of WW and DC (DW and WC). The areas with positive (negative) dependence between precipitation and temperature extremes of DW and WC showed negative (positive) dependence between the two extremes of WW and DC, except for central Asia where the two extremes showed positive dependence in the four compound extremes. During 1901–2024, El Niño (La Niña) tended to induce annual high (low) DW and low (high) WC occurrences in northern South America, southern and central Africa, southern Asia, eastern Australia, and northwestern North America and high (low) WW and low (high) DC occurrences in South America, Africa, western and southern Asia, southern Europe, western North America, and western Australia. The positive (negative) Dipole Mode Index tended to induce high occurrences of compound warm-related (cold-related) extremes in most global land areas. The positive North Atlantic Oscillation (NAO) tended to induce high WW occurrences and low DC occurrences in central and northern Europe, northern and central-eastern Asia, and eastern North America, especially during DJF. This study provides scientific insights into the spatiotemporal characteristics and driving mechanisms of different compound extremes across the globe under a changing climate.</p>","PeriodicalId":13779,"journal":{"name":"International Journal of Climatology","volume":"46 12","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/joc.70491","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Distinct and Synergistic ENSO Modulation of Winter Extreme Rainfall Over Central Vietnam","authors":"Le Van Thien,&nbsp;Phan Van Tan","doi":"10.1002/joc.70487","DOIUrl":"https://doi.org/10.1002/joc.70487","url":null,"abstract":"<div>\u0000 \u0000 <p>Previous studies have primarily focused on tropical cyclone–related extreme rainfall in Central Vietnam, whereas comparatively little attention has been given to extremes during the boreal winter (November–January; NDJ). Recent winter flooding events highlight the need to better understand the large-scale climate drivers of non-cyclonic extreme precipitation. This study investigates the individual and synergistic roles of the El Niño–Southern Oscillation (ENSO) and the East Asian Winter Monsoon (EAWM). To disentangle their coupled influences, a linear regression-based framework is applied to isolate the ENSO-independent monsoonal component (EAWMres). Results show that winter extreme precipitation exhibits robust, statistically significant negative correlations with both ENSO and the total EAWM indices. However, once the ENSO signal is removed, EAWMres shows no significant relationship with rainfall extremes, while the ENSO-related monsoonal component displays stronger and more spatially coherent associations. Dynamical diagnostics indicate that ENSO establishes a favourable large-scale environment by coupling low-level convergence with enhanced upper-level divergence, forming an efficient ‘vertical pump’ that sustains deep convection. In contrast, EAWMres lacks this vertical coherence. Moisture budget analysis further shows that convergence dominates over horizontal advection, particularly in the lower troposphere. This effect is amplified by the Annamite (Truong Son) Range, where orographic lifting concentrates rainfall within a narrow coastal band. These findings provide a physically consistent framework linking large-scale variability with regional topographic effects, offering implications for seasonal predictability and climate risk management.</p>\u0000 </div>","PeriodicalId":13779,"journal":{"name":"International Journal of Climatology","volume":"46 12","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bias Correction of ERA5 Temperature Across Five Topoclimatic Clusters: A Comparative Evaluation of Four Methods","authors":"José Roberto Rozante,&nbsp;Gabriela Rozante","doi":"10.1002/joc.70486","DOIUrl":"https://doi.org/10.1002/joc.70486","url":null,"abstract":"<p>Near-surface air temperature from the ERA5 reanalysis is widely used for climate analysis, impact studies and environmental modelling over South America, but it exhibits systematic and regionally dependent biases that limit its direct applicability. This study aims to improve ERA5 daily maximum (TMAX) and minimum (TMIN) temperatures through physically informed regionalisation and bias correction. South America was clustered into homogeneous topoclimatic regions using <i>k</i>-means, spectral clustering and Gaussian Mixture Models, based on ERA5 thermodynamic variables, geographic coordinates and elevation, with the latter providing the most physically consistent partition into five clusters. Within each cluster, four bias-correction approaches were evaluated: Mean Bias (MB) and Model Output Statistics (MOS), applied at the cluster level, and Spatial Bias Correction (SBC) and a Multi-Layer Perceptron (MLP), which account for spatial variability across the broader domain. All methods were calibrated and assessed using independent subsets of in situ observations. ERA5 shows a pervasive cold bias in TMAX and a warm bias in TMIN, with the largest errors occurring in mountainous and high-latitude regions. All methods reduce these errors, with the MLP providing the most consistent improvements across regions and seasons. However, its performance is interpreted in light of its greater flexibility and ability to represent non-linear spatial–temporal relationships using physically meaningful predictors, rather than as evidence of universal superiority. The comparison reflects differences in modelling approaches, from linear and spatial interpolation to non-linear learning, within a consistent regionalised framework. Model performance is influenced by the spatial distribution of observations. In data-sparse regions such as the Amazon, MB, MOS and SBC are constrained by limited station coverage, whilst the MLP can partially compensate through cross-regional generalisation, which may reflect the transfer of relationships learned in data-rich regions. In mountainous and high-latitude regions, all methods are affected by observational limitations and unresolved physical processes, resulting in higher uncertainty. Overall, the MLP demonstrates strong effectiveness for bias correction and shows potential for predictive applications.</p>","PeriodicalId":13779,"journal":{"name":"International Journal of Climatology","volume":"46 12","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/joc.70486","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Surface and Tropospheric Climatic Trends in the Galápagos Archipelago Based on the Galápagos Archipelago Refined Analysis Dataset","authors":"Benjamin Schmidt,&nbsp;Marco Otto,&nbsp;Frederik Bart,&nbsp;Nazli Turini,&nbsp;Byron Delgado Maldonado,&nbsp;Jörg Bendix,&nbsp;Dieter Scherer","doi":"10.1002/joc.70492","DOIUrl":"https://doi.org/10.1002/joc.70492","url":null,"abstract":"<p>The Galápagos Archipelago, located on the equator in the eastern Pacific, exhibits pronounced seasonal and interannual climate variability influenced primarily by the Inter-Tropical Convergence Zone and the El Niño-Southern Oscillation (ENSO). Despite its ecological significance and vulnerability to climatic changes, limited observational data has hindered long-term analyses of climate trends in the region. This study leverages the newly developed Galápagos Archipelago Refined Analysis dataset, with a 2 km × 2 km grid spacing, derived from high-resolution dynamical downscaling of ERA5 data, to comprehensively examine climatic trends across the archipelago from 1980 to 2023 using both linear regression and Mann-Kendall trend analysis. Our key finding is a positive trend in layer thickness of lower and upper troposphere driven by rising potential air temperature. While linear regression detects significant trends primarily during dry seasons, the Mann-Kendall test reveals additional monotonic warming trends during wet and transitional seasons obscured by strong interannual variability, indicating more pervasive year-round tropospheric warming than linear analysis alone suggests. This tropospheric warming signal suggests increasing atmospheric stability over the archipelago. In contrast, near-surface variables are dominated by strong interannual variability driven primarily by ENSO, and linear regression does not detect statistically significant long-term trends in air temperature, humidity, or precipitation. However, the Mann-Kendall test identifies a significant monotonic warming trend in near-surface air temperature during January–February–March, indicating a subtle wet-season surface signal that is weaker and less spatially consistent than the tropospheric warming. Notably, strong El Niño events before 2000 exhibited substantially stronger precipitation and temperature anomalies than more recent events, suggesting potential changes in ENSO characteristics affecting the region. The observed decoupling between tropospheric warming trends and boundary-layer conditions underscores the need for further investigation into vertical atmospheric dynamics and the mechanisms linking large-scale climate change to local surface conditions on the archipelago.</p>","PeriodicalId":13779,"journal":{"name":"International Journal of Climatology","volume":"46 12","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/joc.70492","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Projection the Risk of Winter Extreme Cold Spells in China Based on Statistical Modelling Under Global Warming of 1.5°C and 2.0°C","authors":"Lianhua Zhu,&nbsp;Jianing Zhang,&nbsp;Yuanxin Zhang,&nbsp;Wei Li,&nbsp;Jun Wang,&nbsp;Yingqi Zhu","doi":"10.1002/joc.70503","DOIUrl":"https://doi.org/10.1002/joc.70503","url":null,"abstract":"<div>\u0000 \u0000 <p>This study used the observed daily minimum temperature from 1995 to 2014 in China, combined with simulations from 21 models from CMIP6, to define and extract characteristic indicators of cold spells from a process-oriented perspective. A method using probability distribution (Cold Spell Model, CSM) is constructed based on extreme value theory, which can effectively characterise the intensity, frequency and duration of cold spells. Results demonstrate that the intensity of extreme cold spells decreases from north to south across China. Northern China typically experiences low-frequency, longer-duration and extreme cold spells, whereas southern China is characterised by shorter-duration events. A cumulative probability distribution transformation method is applied to correct biases in model simulations, showing that bias correction simulation has better performance over the raw simulations. Based on the corrected projections, the extreme cold spells in China are expected to become shorter, less frequent and generally less intense under future warming, with more pronounced changes under the 2.0°C warming compared to 1.5°C warming. However, notable spatial variations exist: the intensity of cold spells decreases in most eastern regions but increases in western regions. The average annual frequency of cold spells generally declines, with more significant changes observed on the Qinghai-Tibet Plateau. Furthermore, the duration of cold spells shortens significantly across most regions. Future cold spell risks in China will generally decrease across most return periods. However, risks are projected to increase for low-frequency (once per year) and short-duration (1-day) extreme events in certain regions, while risks for high-frequency and long-duration events significantly decline. An additional 0.5°C of warming further reduces the probability of cold spells.</p>\u0000 </div>","PeriodicalId":13779,"journal":{"name":"International Journal of Climatology","volume":"46 12","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diverse Multiscale Synergies Underlying Persistent Heavy Rainfall Formation During the Meiyu Period Over the Yangtze-Huaihe Region","authors":"Ziyan Cheng,&nbsp;Suxiang Yao,&nbsp;Wenna Qi","doi":"10.1002/joc.70494","DOIUrl":"https://doi.org/10.1002/joc.70494","url":null,"abstract":"<div>\u0000 \u0000 <p>Persistent heavy rainfall (PHR) during the Meiyu period frequently leads to severe flooding in China. Since the early 2000s, such events have become increasingly common over the Yangtze-Huaihe region, the northernmost sector of China's Meiyu monitoring region, where precipitation exhibits pronounced multiscale characteristics. However, a systematic understanding of how multiscale processes interact to sustain PHR remains lacking. Based on 43 PHR events over the Yangtze-Huaihe region during the Meiyu period of 1961–2020, this study investigates their formation mechanisms from a multiscale perspective and classifies them into three types. Multiscale contribution decomposition reveals that coupling of the background (&gt; 30 days), quasi-biweekly (10–30 days), and synoptic-scale (&lt; 10 days) wind fields with the background moisture field accounts for 93.8% of total precipitation. The events are classified into three types: background-persistent (13 events), synoptic-transient (11 events), and multiscale hybrid (19 events). The background-persistent type is dominated by background circulation with broad, stable moisture transport from the northwestern Pacific. The Meiyu frontal zone is the strongest and most persistent among the three types, which in turn intensifies the upper-level subtropical jet and causes its eastward displacement. The enhanced jet strengthens the secondary circulation at the jet entrance, while the 10–30 days variability gains energy from the basic flow, strengthening the vertical circulation. The synoptic-transient type is dominated by synoptic-scale disturbances (&gt; 54% contribution), with rainfall depending on wave trains propagating along the jet that induce low-level northerly–southwesterly confluence, and the frontal zone shows large variability. The multiscale hybrid type reflects the combined influence of an intensified subtropical jet, a 10–30 days meridional wave train, and intensified synoptic-scale wave trains, with a relatively weak frontal zone. Overall, this study provides a scientific basis for classification-based monitoring and refined forecasting of PHR events over the Yangtze-Huaihe region.</p>\u0000 </div>","PeriodicalId":13779,"journal":{"name":"International Journal of Climatology","volume":"46 12","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterising Vento Norte Downslope Windstorms and Their Thermal Impacts in Southern Brazil","authors":"Cinara Ewerling da Rosa,&nbsp;Michel Stefanello,&nbsp;Diego Portalanza,&nbsp;Mateus da Silva Rebelo,&nbsp;Gervasio Annes Degrazia,&nbsp;Milena Marquesin","doi":"10.1002/joc.70488","DOIUrl":"https://doi.org/10.1002/joc.70488","url":null,"abstract":"<p>This study investigates the meteorological characteristics and associated human thermal discomfort of downslope windstorms known as ‘Vento Norte’ (VNOR; ‘North Wind’ in Portuguese) occurring in the city of Santa Maria, southern Brazil, over 20 years (2004–2023). VNOR events are characterized by unseasonable strong northerly winds, abrupt temperature rises and significant drops in relative humidity. Utilising hourly meteorological data, we identified 189 VNOR episodes, predominantly occurring during austral winter months (June–August), reflecting a seasonal pattern. VNOR events significantly altered local thermal comfort conditions, as demonstrated through a comparative analysis of five biometeorological indices: Effective Temperature with Wind (TEFW), Thermal Discomfort Index (TDI), Temperature–Humidity Index (THI), Human Discomfort Index (HDI) and Humidex (HU). Statistical analyses revealed significant differences between VNOR and non-VNOR periods, with VNOR episodes consistently associated with elevated human thermal discomfort. A detailed examination of representative events further illustrated abrupt changes in meteorological parameters, highlighting the potential for rapid thermal stress in the local population. The present analysis demonstrates the importance of monitoring VNOR phenomena and their thermal impacts and suggests how these downslope windstorms alter local atmospheric conditions, providing an environmental baseline that could support future risk-awareness frameworks and biometeorological monitoring protocols in southern Brazil.</p>","PeriodicalId":13779,"journal":{"name":"International Journal of Climatology","volume":"46 12","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/joc.70488","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Increases in Compound Drought and Hot Event in the Southwestern Tibetan Plateau and Its Link to Land-Atmosphere Interactions","authors":"Xianghui Kong,&nbsp;Aihui Wang,&nbsp;Yue Chen,&nbsp;Yali Zhu,&nbsp;Lu Xia,&nbsp;Xunqiang Bi","doi":"10.1002/joc.70502","DOIUrl":"https://doi.org/10.1002/joc.70502","url":null,"abstract":"<div>\u0000 \u0000 <p>Compound drought and heatwave event (CDHE) exerts profound impacts on high-elevation areas, garnering increasing attention from the scientific community and relevant stakeholders. However, the physical mechanisms of CDHE involving land-atmosphere interaction are not fully understood in high-elevation areas. This study firstly analyzes the variations in CDHE frequency (CDHEF) over the Tibetan Plateau (TP) during the warm season (May–September) from 1980 to 2018. High-frequency CDHE occurs in the southwestern TP, where a significant increasing trend in CDHEF—exceeding 0.5 days per year—has been identified. Due to the semi-arid and semi-humid characteristics in the southwestern TP, we mainly investigate how the land-atmosphere interactions affect the interannual variations of CDHEF over this region. After removing the trend, a strong negative correlation (−0.34) is observed between soil moisture (SM) deficit and CDHEF. During years of persistent SM deficit, near-surface conditions are characterised by positive geopotential height anomalies and negative specific humidity anomalies. Meanwhile, divergence in the lower atmosphere and convergence in the upper atmosphere are observed, accompanied by subsidence throughout the entire atmospheric column over the southwestern TP. These processes work together to create favourable conditions for CDHEs. Furthermore, land-atmosphere interactions are amplified under relatively dry conditions. Reduced SM limits evapotranspiration—particularly ground evaporation and transpiration—which enhances sensible heating and elevates near-surface air temperatures. Concurrently, the lifting condensation level (LCL) grows deeper than the planetary boundary layer (PBL) height, resulting in a positive LCL deficit that further suppresses rainfall formation. The SM-evapotranspiration partitioning relationship reveals that the southwestern TP intends to shift from an energy-limited to a moisture-limited regime during dry years. Particularly, the persistent SM deficit is the potential forcing for the intensification of CDHE based on the analyses of antecedent SM-latent heat flux relationship. These findings highlight a positive feedback mechanism in which land-atmosphere interactions significantly amplify the CDHEF in southwestern TP.</p>\u0000 </div>","PeriodicalId":13779,"journal":{"name":"International Journal of Climatology","volume":"46 12","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in the Frequency, Duration, Intensity, and Dominant Types of Droughts in the Yellow River Basin From 1961 to 2020","authors":"Suping Wang,&nbsp;Qiang Zhang,&nbsp;Jinhu Yang,&nbsp;Haitao Han","doi":"10.1002/joc.70495","DOIUrl":"https://doi.org/10.1002/joc.70495","url":null,"abstract":"<div>\u0000 \u0000 <p>A comprehensive understanding of drought evolution in the Yellow River Basin (YRB) is essential for effective drought mitigation and water resource management. Based on the daily-scale Modified Comprehensive Meteorological Drought Index (MCI), this study analyzes the spatiotemporal characteristics of drought in the YRB over the past 60 years. The main findings are: The average annual drought days exceed 60, with high-frequency areas (&gt; 120 days) concentrated in the upper-middle reaches junction, the eastern middle reaches, and the western lower reaches. Most areas show a decreasing trend in drought days, with the most significant reduction in the source region (20 days/decade). Drought regimes vary regionally: the source region experiences infrequent, short, and mild droughts; the middle-lower section of the upper reaches has infrequent but prolonged and intense droughts; while most middle-lower reaches face frequent, short-duration, yet relatively high-intensity droughts. Spring drought dominates (25%–40%), followed by summer drought (15%–30%), with spring–summer consecutive drought being the most common cross-seasonal pattern. During drought events, precipitation deficits are more pronounced in the middle-lower section of the upper reaches and the lower reaches. Evapotranspiration anomalies are generally higher in the middle-lower reaches. Precipitation-dominated droughts (20%–35%) mainly occur in the middle-lower section of the upper reaches. Evapotranspiration-aggravated droughts (25%–35%) are concentrated in the source region. Synergistic droughts (25%–30%) are mainly found in the eastern middle reaches, the lower reaches, and localized areas. Since 1961, precipitation-dominated droughts have decreased, while evapotranspiration-aggravated and synergistic droughts have increased in most parts of the YRB. Daily-scale monitoring enables a more accurate characterization of drought processes, providing critical insights for regional drought management and supporting ecological conservation and high-quality development in the basin.</p>\u0000 </div>","PeriodicalId":13779,"journal":{"name":"International Journal of Climatology","volume":"46 12","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Regional Temperature Trends and Future Warming Risks in Pakistan Using Bias-Corrected CMIP6 Ensembles and Machine Learning Techniques","authors":"Hamd Ullah,&nbsp;Firdos Khan,&nbsp;Majid Khan,&nbsp;Muhammad Abbas","doi":"10.1002/joc.70497","DOIUrl":"https://doi.org/10.1002/joc.70497","url":null,"abstract":"<div>\u0000 \u0000 <p>Pakistan faces climate-related hazards such as floods, droughts, and heatwaves, driven by diverse climate and rising temperatures. Reliable predictions are crucial for water management, agriculture, and disaster response, but the country's complex terrain requires region-specific assessments. This study improves regional temperature projections by integrating ensembling techniques, statistical bias correction, and machine learning algorithms. Fuzzy C-Means clustering divided Pakistan into six climatically similar regions. CMIP6 model outputs were evaluated and bias-corrected to reduce errors. Temperature trends were estimated using both Sen's slope estimator and Random Forest regression (RFR). Sen's slope identified steady warming trends, while RFR captured nonlinear changes more effectively. Future projections under the SSP2-4.5 and SSP5-8.5 scenarios for three periods (2015–2044, 2045–2074, and 2075–2100) show significant warming, especially in central and southern Pakistan. Spatial analysis shows that warming increases relative to the baseline, notably under SSP5-8.5, with larger increases in lowland and southern areas. The SSP2-4.5 scenario suggests partial stabilisation toward the end of the century, while the SSP5-8.5 scenario predicts accelerated warming that threatens food security, water resources, and public health. Bias correction reduces systematic deviations between modelled and observed data, but uncertainties persist under non-stationary climate conditions. The framework improves regional analysis, yet uncertainties arising from bias-correction assumptions and model limitations should be considered when interpreting results. By integrating these techniques, the study fills a gap in Pakistan's climate research, offering localised insights into future warming and valuable guidance for climate adaptation and policymaking.</p>\u0000 </div>","PeriodicalId":13779,"journal":{"name":"International Journal of Climatology","volume":"46 12","pages":""},"PeriodicalIF":3.2,"publicationDate":"2026-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}