Influence Of El Nino Southern Oscillation Research Articles

Northwestern Pacific Oceanic circulation shaped by ENSO

The intricate currents of the Northwest Pacific Ocean, with strong manifestations along the westside rim, connect tropical and subtropical gyres and significantly influence East Asian and global climates. The El Niño/Southern Oscillation (ENSO) originates in the tropical Pacific Ocean and disrupts this ocean circulation system. However, the spatiotemporal dependence of the impact of ENSO events has yet to be elucidated because of the complexities of both ENSO events and circulation systems, as well as the increased availability of observational data. We thus combined altimeter and drifter observations to demonstrate the distinct tropical and subtropical influences of the circulation system on ENSO diversity. During El Niño years, the North Equatorial Current, North Equatorial Countercurrent, Mindanao Current, Indonesian Throughflow, and the subtropical Kuroshio Current and its Extension region exhibit strengthening, while the tropical Kuroshio Current weakens. The tropical impact is characterized by sea level changes in the warm pool, whereas the subtropical influence is driven by variations in the wind stress curl. The tropical and subtropical influences are amplified during the Centra Pacific El Niño years compared to the Eastern Pacific El Niño years. As the globe warms, these impacts are anticipated to intensify. Thus, strengthening observation systems and refining climate models are essential for understanding and projecting the enhancing influences of ENSO on the Northwest Pacific Oceanic circulation.

Increase in the variability of terrestrial carbon uptake in response to enhanced future ENSO modulation

El Niño–Southern Oscillation (ENSO) is a major driver of climate change in middle and low latitudes and thus strongly influences the terrestrial carbon cycle through land–air interaction. Both the ENSO modulation and carbon flux variability are projected to increase in the future, but their connection still needs further investigation. To investigate the impact of future ENSO modulation on carbon flux variability, this study used 10 CMIP6 earth system models to analyze ENSO modulation and carbon flux variability in middle and low latitudes, and their relationship, under different scenarios simulated by CMIP6 models. The results show a high consistency in the simulations, with both ENSO modulation and carbon flux variability showing an increasing trend in the future. The higher the emissions scenario, especially SSP5-8.5 compared to SSP2-4.5, the greater the increase in variability. Carbon flux variability in the middle and low latitudes under SSP2-4.5 increases by 30.9% compared to historical levels during 1951–2000, while under SSP5-8.5 it increases by 58.2%. Further analysis suggests that ENSO influences mid- and low-latitude carbon flux variability primarily through temperature. This occurrence may potentially be attributed to the increased responsiveness of gross primary productivity towards regional temperature fluctuations, combined with the intensified influence of ENSO on land surface temperatures.摘要ENSO是中低纬度地区气候系统的主要驱动因素, 对陆地碳循环有重要影响. 本研究基于10个CMIP6地球系统模式, 分析了不同情景下ENSO变率与中低纬度地区总初级生产力变率的关系. 结果显示, 未来ENSO变率和总初级生产力变率在未来多数模式均显示为增加. 在未来情境下(2051-2100年), 中低纬度地区的总初级生产力变率较历史时期(1951–2000年)增加了30.9%(SSP2-4.5), 58.2%(SSP5-8.5). 进一步分析表明, ENSO主要通过温度影响中低纬度碳通量变率. 这种现象可能归因于总初级生产力对温度的响应增强, 以及ENSO对陆地表面温度的影响.

Influence of El Niño on parameters of the middle and upper atmosphere over Eastern Siberia according to reanalysis and model data in winter

One of the most important climate-forming phenomena in the ocean—atmosphere system is the El Niño Southern Oscillation (ENSO) events, which manifest themselves with varying intensity in almost all regions of the globe. The central regions of Eurasia are farthest from the tropics of the Pacific Ocean, the regions where ENSO originates. There are different points of view regarding the nature of the ENSO effect on these regions. In the presented work, the influence of ENSO on the upper atmosphere of the Northern Hemisphere and, in particular, on the upper atmosphere of Eastern Siberia is estimated using model calculations and reanalysis data. The results of the analysis show that the large-scale structures of the atmospheric response to the ENSO events in the Northern Hemisphere are similar according to modeling and reanalysis, yet the regions of Eastern Siberia are on the periphery of the main signal and there are significant differences in estimated effects from one case of El Niño and La Niña to another. In January, ENSO has the greatest impact on the middle atmosphere of the polar regions of the Northern Hemisphere. Over Eurasia and Eastern Siberia, the atmospheric response to the ENSO events turned out to be weak or absent.

Влияние Эль-Ниньо на параметры средней и верхней атмосферы над Восточной Сибирью по данным реанализа и моделирования в зимний период

One of the most important climate-forming phenomena in the ocean—atmosphere system is the El Niño Southern Oscillation (ENSO) events, which manifest themselves with varying intensity in almost all regions of the globe. The central regions of Eurasia are farthest from the tropics of the Pacific Ocean, the regions where ENSO originates. There are different points of view regarding the nature of the ENSO effect on these regions. In the presented work, the influence of ENSO on the upper atmosphere of the Northern Hemisphere and, in particular, on the upper atmosphere of Eastern Siberia is estimated using model calculations and reanalysis data. The results of the analysis show that the large-scale structures of the atmospheric response to the ENSO events in the Northern Hemisphere are similar according to modeling and reanalysis, yet the regions of Eastern Siberia are on the periphery of the main signal and there are significant differences in estimated effects from one case of El Niño and La Niña to another. In January, ENSO has the greatest impact on the middle atmosphere of the polar regions of the Northern Hemisphere. Over Eurasia and Eastern Siberia, the atmospheric response to the ENSO events turned out to be weak or absent.

Winter precipitation predictability in Central Southwest Asia and its representation in seasonal forecast systems

In Central Southwest Asia (CSWA; 22°N to 40°N and 30°E to 70°E), winter (November to February) precipitation contributes up to 70% of the annual mean, but substantial interannual variations exist. Dynamical models exhibit subpar predictability in this region, but the limits of their skills are not well established. Here, we identify the tropical and extratropical forcings that explain ~75% of area-averaged seasonal variability in CSWA winter precipitation. Tropical forcing comes from the indirect El Niño-Southern Oscillation (ENSO) pathway, the leading mode of tropical Indian Ocean precipitation variability. This mode is coupled with ENSO-related Pacific Ocean sea surface temperature variability. A direct ENSO influence on CSWA does not extend beyond its Indian Ocean connection. Extratropical forcing comes from a large-scale mode of internal atmospheric variability. The spatial structure, variability of tropical forcing, and teleconnection with CSWA winter precipitation are skillfully depicted in two seasonal forecasting systems: the fifth-generation seasonal forecasting system (SEAS5) and Seamless System for Prediction and Earth System Research (SPEAR). Extratropical forcing’s spatial structure is also produced skillfully in the two modelling systems; however, the representation of its interannual variability and teleconnection requires improvement. While SEAS5 displays skill in representing extratropical forcing influence on CSWA winter precipitation and marginal skill in reproducing interannual variability, SPEAR has negligible ability in both areas. Consequently, these models have limited predictive skills over CSWA in winter. While improvements in representing extratropical forcing may be inherently limited as it arises from internal atmospheric variability, further research is needed to establish its predictability limits fully.

Seasonal Dependence of Recovery From Surface Cooling Induced by Strong Tropical Volcanic Eruptions

AbstractThis study investigates the response of surface air temperature (SAT) to strong tropical volcanic eruptions (STVEs), focusing on the seasonal anchoring of SAT recovery, using the Coupled Model Intercomparison Project 5 (CMIP5) and CMIP6 climate model outputs. The decrease in SAT was more significant in the Northern Hemisphere than in the Southern Hemisphere. After the STVEs, shortwave radiation at the surface (SW) decreased rapidly and reached a minimum in approximately 6 months, whereas the decrease in SAT lasted for approximately 1 year; thus, the SAT minima lagged behind those of SW. The recovery of SAT from the major minimum SAT after the STVEs occurred in the same seasons, the second boreal autumn and winter. The SAT recovery occurred during the climatologically low solar radiation season after the STVEs. During this season, the decreasing effects of the downward SW (DSRS) by volcanic aerosols could become negligible. The weakening of the decrease in SAT and DSRS had a seasonal cycle in the high‐latitude regions of both hemispheres, which could be a significant factor in the seasonal alignment of returning SATs. Furthermore, the SAT response to the El Niño–Southern Oscillation (ENSO) was examined using composite analysis based on the initial state of ENSO. The influence of ENSO on surface cooling after the STVE was at least 1/5 that of the STVEs and might exceed that of the STVEs, particularly in moderate STVEs. These results were commonly found in the CMIP5 and CMIP6 climate models.

Causes of Diverse Impacts of ENSO on the Southeast Asian Summer Monsoon among CMIP6 Models

Abstract This study examines the fidelity of 47 models from phase 6 of the Coupled Model Intercomparison Project (CMIP6) in representing the influence of El Niño–Southern Oscillation (ENSO) on the Southeast Asian summer monsoon (SEASM) during the ENSO decaying summer. The response of the SEASM to ENSO shows a large model spread among the models, some of which even simulate opposite signs of SEASM anomalies compared to the observed values. The bad-performance models (BPMs) are therefore selected to be compared with both the good-performance models (GPMs) and observations to explore the possible causes of the deficiency. Results show that in the BPMs, the ENSO-related warm sea surface temperature (SST) anomalies extend too far westward in the western equatorial Pacific (WEP) and they do not dissipate in the El Niño decaying summer in comparison with those in the GPMs and observations, interfering with the effect of ENSO on the SEASM. The slow decay of WEP SST anomalies from the El Niño mature winter to the decaying summer in the BPMs is mainly caused by a weak negative shortwave radiation feedback due to a low sensitivity of convection to local SST anomalies, which is related to the cold bias in climatological SST over this region. On the other hand, from the mature winter to the decaying summer of El Niño, the El Niño–related anomalous eastward current does not reverse to a westward current in the BPMs, which also contributes to the slow decay of WEP SST anomalies via inducing excessively persistent warm zonal advection. Significance Statement We investigate the possible causes of the diverse impacts of El Niño–Southern Oscillation (ENSO) on the Southeast Asian summer monsoon (SEASM) among 47 CMIP6 models. We find that a plausible reason for the deficiency of some models in simulating the influence of ENSO on the monsoon is that the sea surface temperature (SST) anomalies associated with ENSO are unrealistic in the western equatorial Pacific (WEP) in these models. Further diagnoses indicate that the unrealistic WEP SST anomalies are related to the cold bias of the climatological SST, which could lead to a weak negative shortwave radiation feedback and excessively persistent warm zonal advection. The information provided in this study is useful for improving the skill of the climate models in representing the ENSO–SEASM relationship.

Karadeniz'de 2000-2022 Yılları Arasında Yüzey Sıcaklığının Mekansal ve Zamansal Değişimi

This study presents a comprehensive assessment of the spatio-temporal variability of Sea Surface Temperature (SST) in the Black Sea at monthly to interannual scales, with a focus on understanding its connection to major large-scale atmospheric forcing during the period 2000-2022. Monthly variations of SST in the Black Sea reveal distinct seasonal patterns. The study evaluates the potential impacts of large-scale atmospheric patterns on interannual SST variations using climate indices such as the North Atlantic Oscillation (NAO), East Atlantic/West Russia (EA-WR) and El Niño-Southern Oscillation (ENSO) during the winter months. The results indicated that these large-scale atmospheric oscillations played a substantial role in influencing SST anomalies, with the NAO and EA-WR indices particularly affecting the Black Sea's SST anomalies. The NAO index exhibited negative values during warm winters and positive values during cold winters, with extreme cold and warm winters corresponding to specific years, as observed in 2003, 2006, 2012, 2017 (cold) and 2018, 2020, 2021 (warm). Notably, the relationship between NAO and SST anomalies was not as dominant during 2000-2022. This difference might be explained by the combined influence of NAO and ENSO, which is beyond the scope of this study. The EA-WR pattern was identified as another significant large-scale atmospheric dynamic affecting the Black Sea's SST. Although it explains the cold SST anomalies in certain years, it cannot account for extreme warm SST years. While the influence of ENSO remains somewhat inconclusive for the extreme warm period, the SST pattern between 2016-2022 aligns closely with El Niño events, particularly in 2018 and 2021 when positive SOI index values coincide with warm SST years in the Black Sea.

Interannual variability of the South Atlantic subtropical mode water: Investigating the early aughts shift and its relationship to ENSO modulations

The South Atlantic subtropical mode water (SASTMW) is a conspicuous volume of water formed during winter and early spring that occupies the mid-latitudes of the South Atlantic. Here, we aim to investigate the interannual variability of the SASTMW's volume in response to remote processes influenced by atmospheric teleconnection. We utilized the Simple Ocean Data Assimilation (SODA) ocean reanalysis to identify this particular mode water. The SASTMW's volume time series underwent a shift during the early aughts, with the frequency spectrum changing from broad and sparse interannual peaks during 1980–2001 to narrow and frequent peaks during 2002–2018, following the interdecadal shift of El Niño–Southern Oscillation (ENSO) that occurred in 1999. Hence, the influence of ENSO on SASTMW was evaluated for each of the two periods. From 1980 to 2001, in the western side of the basin, SASTMW's volume reached its peak 21 months after the occurrence of an El Niño, and after 43 months it became thinner. The opposite pattern occurred after a La Niña event, with stronger events having a greater impact on the SASTMW. In the 2002–2018 period, the largest correlations were observed in the eastern part of the basin, with significantly shorter lags of 6–20 months.

Increasing ENSO variability synchronizes tree growth in subtropical forests

Rising El Niño–Southern Oscillation (ENSO) variability is expected to influence Earth's forest ecosystems, through changes in how coordinated annual tree growth is across large spatiotemporal scales. However, the mechanisms by which changes in ENSO variability affect tree growth in subtropical forests remains poorly understood. We use a newly built tree ring network collected from 4,028 trees at 144 forest locations across East Asian subtropical forests (EASF), to assess long-term influences of ENSO on the spatiotemporal variability in tree radial growth across China at subcontinental scales (∼2,000 km). Our results demonstrate a west-east dipole pattern of synchronized tree growth in EASF tree populations, with positive growth responses to El Nino in southeastern China, and negative growth responses in southwestern China, likely due to different patterns in moisture limitation. Specifically, the likely contrasting effects of ENSO on drought limitation along a longitudinal gradient resulted in trees that grew more in El Niño years in eastern populations, but less in western populations. Our results also show that increasingly severe El Niño/La Niña years have caused a sharp rise in tree growth coherence over the past 150 years in these moisture-limited populations. Increasing ENSO variability, as is expected with climate change, may potentially further destabilize subtropical forest ecosystems by synchronizing tree growth to an unprecedented level, with unknown consequences for forest stability and resilience.

Recent Strengthening of the ENSO Influence on the Early Winter East Atlantic Pattern

Previous studies have demonstrated that the influence of the El Niño–Southern Oscillation (ENSO) on the Euro-Atlantic atmospheric circulation varies considerably during the boreal winter. Compared to the late winter (January–March) relationship, the early winter (November–December) teleconnection is more uncertain and less understood. In this paper, we revisited this early winter regional ENSO teleconnection using the Hadley Centre Global Sea Ice and Sea Surface Temperature (HadISST) and the European Centre for Medium-Range Weather Forecasting (ECMWF) fifth generation reanalysis (ERA5) datasets for the period 1979–2022. It was found that the signal projected well onto the second dominant mode of Euro-Atlantic atmospheric variability, the East Atlantic Pattern (EAP), rather than the previously mentioned North Atlantic Oscillation (NAO). This influence is associated with ENSO-induced dipolar convection anomalies in the Gulf of Mexico and Caribbean Sea (GMCA), which leads to an EAP via exciting Rossby waves propagating northward into the North Atlantic. We further revealed that this ENSO–EAP teleconnection underwent a pronounced interdecadal strengthening around the late 1990s. Prior to the late 1990s, the convective response to ENSO in the GMCA was weak. The atmospheric responses over the Euro-Atlantic were mainly driven by the ENSO-induced convective forcing in the tropical Indian Ocean, which favors an NAO-like pattern. In contrast, since the late 1990s, ENSO has induced stronger precipitation anomalies in the GMCA, which exert a dominant influence on the Euro-Atlantic atmospheric circulation and produce an EAP. These results have useful implications for the further understanding of ENSO-related early winter atmospheric and climate variability in the Euro-Atlantic region.

Evolution of ENSO‐related seasonal precipitation anomalies in East Asia: A robustness revisit

AbstractThe El Niño–Southern Oscillation (ENSO) is a major source of seasonal climate predictability and a key predictor for East Asian precipitation. However, the impacts of ENSO on East Asian precipitation are extremely complex and still controversial. Thus, it is necessary and significant to use various (observational and model) data sources to further examine the robustness of the impacts. This study revisits the evolution of the ENSO‐related seasonal precipitation anomalies in East Asia, including symmetric and asymmetric impacts of El Niños and La Niñas, the differences in the influences of eastern Pacific (EP) and central Pacific (CP) El Niños, and the interdecadal change of ENSO influences. The ENSO impact on East Asian precipitation has weakened (strengthened) in the ENSO's developing (decay) phase in the recent two decades. The ENSO impacts are robust in (i) southern China‐lower reaches of the Yangtze River‐southern Japan around the ENSO's mature phase, (ii) western North China in the developing phase and (iii) southwestern China in the decay phase. The distribution of East Asian precipitation anomalies is asymmetric in El Niño and La Niña years. The model simulations forced with observed sea surface temperature generally reproduce the observed evolution of seasonal precipitation anomalies associated with ENSO and confirm the robust impact of ENSO in East Asia. These results indicate the necessity to consider the asymmetric impact of El Niños and La Niñas, to distinguish the El Niño flavours for their impact on the East Asian climate, and to include the interdecadal variation of ENSO influence in addressing East Asian climate anomalies.

Influence of climate variability modes over wind-sea and swell generated wave energy

Wave energy is one of the cleanest renewable sources of energy generated through the motion of wind-sea and swell waves. This study examines the influence of different climate variability modes over global wave energy generated from wind-sea (PW) and swell waves (PS) during 1950–2021 using the ERA5 reanalysis dataset. The major climate modes, such as El Niño Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Indian Ocean Dipole (IOD), and Southern Annular Mode (SAM) are considered during four boreal seasons. Wave energy extremes are determined using a non-stationary generalized extreme value analysis. The significant positive influence of ENSO on mean and extreme PS is evident over the northeast and central Pacific Ocean (PO) during December–February (DJF), and weakens during March–May (MAM). The strongest NAO response to PW and PS is evident during DJF as a tripolar and dipolar pattern over the north Atlantic Ocean, respectively. Further, PW responses due to IOD include significant increases over the Bay of Bengal and eastern Indian Ocean (IO) during JJA, which extend towards the central IO during SON. Lastly, SAM influence over PW occurs as a dipole pattern in the Southern Ocean (SO), i.e., positive anomalies in between 55°S and 65°S and negative anomalies in between 30°S and 55°S.

Rapid increase in warm‒wet compound extreme events with high health risks in southern China: Joint influence of ENSO and the Indian Ocean

High temperature and high humidity pose notable threats to the health and survival of humans, and the impact of compound extreme events involving multiple meteorological elements is usually greater than the sum of the impacts of individual extreme events. However, there is limited research on the compound extreme meteorological events, defined based on the extreme of health risks rather than just the extreme of meteorological elements, necessitating further investigation into their characteristics and underlying driving factors. Using daily records of emergency ambulance dispatches from selected Chinese cities, together with daily average temperature and relative humidity data, this study identified and quantified warm‒wet compound extreme events with high health risks (HRWWs) that occurred in southern China during 1979–2022. Results revealed that HRWWs were most prevalent in the coastal region of southern China. The annual frequency of HRWWs across China underwent a marked shift in 2014, with the rapid increase in recent years primarily contributed by the increase in summer HRWWs and advance and extension of the period of occurrence of HRWWs in summer. Further analysis indicated that the changes in HRWWs in southern China during summer were primarily regulated by the El Niño‒Southern Oscillation (ENSO) of the preceding winter and the springtime Indian Ocean basin-wide (IOBW) mode. El Niño and Indian Ocean warming force a reverse Walker circulation in the tropical Indian Ocean‒western Pacific, strengthening the Philippine anticyclone (PAC) in summer. This weakens convection in the northwestern Pacific and enables the western Pacific subtropical high to extend westward over coastal areas of southern China. The resulting abnormal atmospheric circulation causes prevailing subsidence over southern China, which is unfavorable for precipitation but conducive to maintaining high surface temperatures. Despite reduced precipitation, water vapor flux is increased owing to strengthened southwesterlies associated with the PAC that enhance regional humidity. Consequently, as temperature and humidity levels rise, HRWWs occur more frequently in southern China, as evidenced since 2014. Further analysis suggested that the contribution of intensification of IOBW warming to the sudden increase in HRWW occurrence over the past decade has been greater than that of ENSO.

ANALISIS KARAKTERISTIK SPASIAL DAN TEMPORAL HOTSPOT DI TAMAN NASIONAL SEBANGAU PROVINSI KALIMANTAN TENGAH

Sebangau National Park, in Central Kalimantan Province, is a wetland conservation area. In 2015, forest and land fires resulted in 455 hectares being burned. The identification of hotspots in this study is based on the number and distribution of hotspots based on satellite imagery data from the Moderate Resolution Imaging Spectroradiometer (MODIS) in 2001–2020. This study identifies hotspots by looking at the influence of rainfall and ENSO (El Nino Southern Oscillation) conditions. The method used is the method of spatial and temporal analysis. The aim of this study was to determine the characteristics of the hotspot distribution pattern in Sebangau National Park, Central Kalimantan Province, both spatially and temporally. There is a similarity between the temporal and spatial characteristics of hotspots in the number of significant additions to the number of hotspots in August, September, and October. The influence of monsoonal rainfall types and climates such as ENSO (El Nino Southern Oscillation) greatly influences the occurrence of hotspot events in Sebangau National Park, Central Kalimantan Province. The distribution pattern of hotspots in Sebangau National Park, Central Kalimantan Province, peaked in October, and the worst addition to the number of hotspots occurred in 2015, when these conditions occurred during the dry season and when the ENSO index (El Nino Southern Oscillation) showed +2.6, where these conditions included strong El Nino categories.

Seasonal Variation of Rainfall in Indonesia under Normal Conditions without ENSO and IOD Events from 1981-2021

This study explores the seasonal rainfall variation in Indonesia under normal conditions, excluding the influence of El-Nino Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) events. Monthly rainfall data is sourced from the CHIRPS dataset, and wind and atmospheric movement data are obtained from the ECMWF ERA-5 dataset. Identification of normal conditions relies on the ONI and DMI indices. Results reveal that the seasonal rainfall patterns during these normal conditions align with previous studies encompassing all atmospheric conditions. Indonesia typically witnesses one or two peaks in rainfall annually, notably in December-January-February (DJF), May-June (MJ), and March-April-May (MAM), consistent with established rainfall zone classifications in earlier research. A nuanced discrepancy emerges in the timing of the May-June peak, previously noted in June-July. The congruence in peak rainfall patterns during normal conditions, as observed in prior comprehensive research, implies a negligible influence of ENSO and IOD on the timing of seasonal rainfall peaks. Although ENSO and IOD may impact the amplitude of seasonal variation, particularly in Indonesia's eastern and western regions, they do not alter the temporal occurrence of rainfall peaks. Consequently, the timing of rainfall peaks in Indonesia predominantly reflects the combined influence of the Asian and Australian monsoons.

The monthly evolution of precipitation and warm conveyor belts during the central southwest Asia wet season

Abstract. Understanding the nature of precipitation over central southwest Asia (CSWA), a data-sparse, semi-arid region, is important given its relation to agricultural productivity and the likelihood of hazards such as flooding. The present study considers how daily precipitation and local vertical motion – represented by warm conveyor belts (WCBs) – evolve from November to April over CSWA. First we compare several precipitation datasets, revealing that the seasonality of daily precipitation is consistent across estimates that incorporate satellite information, while total accumulation amounts differ substantially. A common feature across datasets is that the majority of precipitation occurs on the few days when area-averaged accumulation exceeds 4 mm, which are most frequent in February and March. The circulation pattern associated with heavy (< 4 mm d−1) precipitation days evolves within the wet season from a southwest–northeast tilted couplet of circulation anomalies in January and February to a neutrally tilted monopole pattern in April. El Niño conditions are associated with more heavy precipitation days than La Niña conditions, with both enhanced WCB frequency and moisture transport observed during the former. An exception to this is found in January, when precipitation, WCB frequency, and moisture do not increase, despite a similar increase in surface cyclones to other months, suggesting that precipitation changes cannot always be inferred from cyclone frequency changes. Nonetheless, our results generally support prior connections made between the El Niño–Southern Oscillation (ENSO) and seasonal-to-interannual precipitation anomalies and extend this connection to one between the slowly evolving ENSO influence and transient and local vertical motion represented by WCBs.

Analysis of ENSO influence on the solar and wind potential of the department of La Guajira

ABSTRACT This study explores how solar radiation and wind speed in La Guajira vary in response to El Niño/Southern Oscillation (ENSO) events. Climatic data were collected and analysed at three iconic locations: Upper Guajira, Middle Guajira, and Lower Guajira, over a span of three decades. The data were obtained from reliable sources such as IDEAM and NASA stations. To identify El Niño and La Niña periods, Southern Oscillation Index (ONI) data were utilised. Subsequently, the data underwent detailed statistical analyses, including hypothesis testing. During El Niño, solar radiation is altered solely in Lower Guajira; for La Niña, no significant changes in solar radiation across the region are observed. Wind speed, for the most part, remains unaffected by the studied climatic phenomena in these areas, with an exception in Middle Guajira during La Niña, where it is notably influenced.

The Influence of ENSO on the Long‐Term Water Storage Anomalies in the Middle‐Lower Reaches of the Yangtze River Basin: Evaluation and Analysis

AbstractRecent extreme events in the Middle‐Lower reaches of the Yangtze River basin (MLYRB) are proven to be possibly linked to the El Niño‐Southern Oscillation (ENSO) events as indicated by terrestrial water storage anomaly (TWSA). But the relatively short observation time of Gravity Recovery and Climate Experiment series missions (2002–2017; 2018–present) affects the robustness of the evaluation of TWSA. Here, the applicability of four long‐term TWSA data sets (since 1979) in the MLYRB is evaluated first using an evaluation framework including two completely independent tests. After selecting the optimal one, we investigate the effects of ENSO on TWSA in the MLYRB at the basin, subbasin, and grid cell scales, respectively. Results show that ENSO, especially the Eastern Pacific type ENSO has had a significant impact on TWSA variations in the MLYRB and its two subbasins (the Dongting Lake basin and the Poyang Lake basin) since 1979 with correlation coefficients at 0.56–0.65 and time lags at 5–6 months. However, TWSAs in the other two subbasins (the Hanjiang River basin and the Mainstream River basin) have almost no correlation with ENSO. Further analysis reveals that compared with human activity that has a limited impact on TWSA, precipitation is one of the key inducements for regional water storage changes in these two subbasins, and the no correlation between ENSO and TWSA is mainly caused by the weak link between ENSO and precipitation.

A two-centennial perspective on spatially compounding hydroclimate events in arid and semi-arid north China

Spatially compounding hydroclimate events, means the droughts or pluvials occurring concurrently in different areas, are more damaging to society than those occurring locally. However, the short length of instrumental climate data hampers our understanding of the variability and driving mechanism of spatially compounding hydroclimate events in the past. Here, six tree-ring chronologies along a latitudinal gradient from the arid and semi-arid north China were used to analyze the variation of spatially compounding hydroclimate events over the past two centuries (1821–2017 CE). The results show that the frequency of spatially compounding droughts has increased, while that of spatially compounding pluvials has decreased since 1950s. Composite analysis with sea surface temperature indicated that the occurrence of spatially compounding hydroclimate events in the study area was related to El Niño–Southern Oscillation (ENSO) events in the prior winter. Furthermore, we found the phase of Pacific Decadal Oscillation (PDO) modulates the influence of ENSO on spatially compounding hydroclimate events. Compounding drought is most common during El Niño and positive phase of PDO, while compounding pluvials is most common during La Niña and negative phase of PDO. These findings offer a reference for the early warning of drought risk and may benefit disaster prediction and mitigation for the north China.