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The projected increase in coastal risk requires a reevaluation of coastal risk reduction strategies. A multi-model approach is proposed to examine the variability of coastal storms influenced by climate change and El Niño Southern Oscillation (ENSO). To this end, the historic coastal storm of August 8 2015, resulting from a local extratropical cyclone (ETC) off the central Chilean coast, was analyzed through the coupling of the WRF atmospheric model, Delft3D FM (D-FLOW and D-WAVE modules), and EOT20 astronomical tide model. The results show that the characteristics of local ETCs are susceptible to regional temperature gradients associated with climate change and ENSO. The coastal storm of August 8 2015, presented a decrease in wave height and counterclockwise rotation of wave direction along the Chilean coast under the climate change scenario. Meanwhile, the ENSO scenarios under cold conditions generated a ETC track's displacement toward the north, causing both an increase in wave height along the coast of the Antofagasta and Atacama regions and a decrease in wave height in the Valparaíso, O'Higgins, and Maule regions. Findings from this study emphasize the importance of considering dynamic design for coastal structures rather than traditional methods to adapt to changing storm patterns. [ABSTRACT FROM AUTHOR]

Following triple La Niña events during 2020–2022, the future evolution of climate conditions over the tropical Pacific has been a focused interest in ENSO-related communities. Observations and modeling studies indicate that an El Niño event is occurring in 2023; however, large uncertainties remain in terms of its detailed evolution, and the factors affecting its resultant amplitude remain to be understood. Here, a novel deep learning-based Transformer model is adopted to make real-time predictions for the 2023–2024 climate conditions in the tropical Pacific. Several key fields vital to the El Niño and Southern Oscillation (ENSO) in the tropical Pacific are collectively and simultaneously utilized in model training and in making predictions; therefore, this purely data-driven model is configured in both training and predicting procedures such that the coupled ocean-atmosphere interactions are adequately represented. Also similar to dynamic models, the prediction procedure is executed in a rolling manner to allow ocean-atmosphere anomaly exchanges month by month; the related key fields during multi-month time intervals (TIs) prior to prediction target months are taken as input predictors, serving as initial conditions to precondition the future evolution more effectively. Real-time predictions indicate that the climate conditions in the tropical Pacific are surely to develop into an El Niño state in late 2023. Furthermore, sensitivity experiments are conducted to examine how prediction skills are affected by the input predictor specifications, including TIs during which information on initial conditions is retained for making predictions. A comparison with other dynamic coupled models is also made to demonstrate the prediction performance for the 2023–2024 El Niño event. [ABSTRACT FROM AUTHOR]

The Southwest Atlantic (SWA) is an important region for the Caretta caretta characterized by unique genetic lineages; however, their demographic evolution is still misunderstood. In this study, we evaluated the demographic patterns of four SWA rookeries using D-loop and microsatellites data looking for expansion and bottlenecks signals. Then, we simulated several colonization scenarios for the SWA using Approximate Bayesian Computation. The best-supported scenario indicated that loggerheads might have colonized the SWA region once by the ancient lineage of ES/k3 that signals a sharing ancestry history, and from it originated the other lineages by divergence and introgression processes, explaining the high admixture levels between their rookeries and genetic clusters. The D-loop recovered population stability in the past. Still, microsatellites identified sharp recent bottleneck events, which the Last Glacial Maximum, El Niño Southern Oscillation, and anthropogenic actions may have triggered. Thus, we provide, for the first time, a complete assessment of the life history and colonization of loggerhead into the SWA, demonstrating differences between markers (matrilinear and biparental) that may bias our understanding of their genetic and demographic patterns, and which should be considered for conservation programs at a global scale. [ABSTRACT FROM AUTHOR]

Daily 7Be activity concentrations data across 21 global locations between 2010 and 2017 from the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) were analyzed using multifractal formalism. The multifractal detrended fluctuation analysis revealed that 7Be distribution across the 21 locations are multifractal (0.17<α<0.66) with a wide range of fractal exponents. The observed multifractality was found to be statistically significant except at two locations (RN45 and RN47). The multifractal strength (α) and Holder’s exponent (α0) were used to group the locations into 3 clusters with K-means algorithm. The relationship between 7Be and five drivers (Southern Oscillation Index — SOI, North Atlantic Oscillation — NAO, Total Sunspot number — Tot_SN, Northern hemisphere Sunspot number — NH_SN and Southern hemisphere sunspot number — SH_SN) was investigated using multifractal detrended cross-correlation analysis. The multifractal cross-correlation between 7Be and drivers was found to be 0.06–0.21(SOI), 0.08–0.23 (NAO), 0.04–0.27 (Tot_SN), 0.05–0.25 (NH_SN) and 0.04–0.27 (SH_SN). NAO was found to be the strongest driver of 7Be. The location, RN16 in Yellowknife Canada, showed strong cross-correlation with the five drivers. [ABSTRACT FROM AUTHOR]

Modes of climate variability, such as the El Niño Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Atlantic Multi‐decadal Oscillation (AMO), have been shown to have large impacts on North American hydroclimate through their atmospheric teleconnections. However, short instrumental records limit our ability to examine the long‐term stability (or stationarity) of hydroclimate teleconnections. Here, we use two last millennium (LM) paleoclimate data assimilation (DA) products to assess the stationarity of hydroclimate teleconnections over two key regions: the southwestern U.S. and Lower Mississippi River basin. Moving correlations between climate indices and regional hydroclimate expose highly nonstationary regional hydroclimate teleconnections with significant periodic variations on multi‐decadal and multi‐centennial timescales. Although limitations of the DA products prohibit a robust analysis of climate mode intensity, consistent sea surface temperature (SST) patterns between DA products during strong and weak teleconnection periods suggest that changing teleconnection strength is driven by the changing relationships between climate modes over the LM. Although our results are sensitive to proxy availability, the DA techniques provide novel insight into the nonstationarity and long‐term variability of North American hydroclimate teleconnections. This work provides a baseline for teleconnection behavior from DA products, which is potentially valuable for decadal prediction. Plain Language Summary: Changing sea‐surface temperature (SST) patterns in the tropical Pacific, the North Pacific, and the North Atlantic have been shown to affect North American rainfall and modulate hazards such as drought and flooding. However, the relatively short time period of observations during the 20th century limits our ability to assess the reliability and predictability of the relationship between these SST patterns and regional rainfall amounts. This work uses a technique that combines records of past climate, such as corals, ice cores, and trees, with climate models to investigate SST‐rainfall relationships over North America during the last millennium with a focus on two key regions: the southwestern U.S. and the Lower Mississippi River basin. We find that, in the context of the past 1000 years, rainfall variability driven by SST patterns changes on decadal to centennial timescales. The strength of SST‐rainfall relationships is modulated by SST patterns in different ocean basins. Our results quantify the natural range of North American rainfall variability in the time before the industrial period of strong human influence, such as fossil fuel pollution on climate, which harbors implications for long‐term water management and hydroclimate risk assessment in the 21st century. Key Points: ENSO, PDO, and AMO‐driven rainfall anomalies over North America are evaluated in paleoclimate data assimilation productsHydroclimate teleconnections are variable over the last millennium but are driven in part by predictable SST patternsAssessing teleconnection stationarity offers a robust estimate of the range of North American hydroclimate without anthropogenic forcing [ABSTRACT FROM AUTHOR]

Accurate prediction of the extreme phases of the El Niño Southern Oscillation (ENSO) is important to mitigate the socioeconomic impacts of this phenomenon. It has long been thought that prediction skill was limited to a 6 months lead time. However, Machine Learning methods have shown to have skill at lead times up to 21 months. In this paper we aim to explain for one class of such methods, i.e. Reservoir Computers (RCs), the origin of this high skill. Using a Conditional Nonlinear Optimal Perturbation (CNOP) approach, we compare the initial error propagation in a deterministic Zebiak-Cane (ZC) ENSO model and that in an RC trained on synthetic observations derived from a stochastic ZC model. Optimal initial perturbations at long lead times in the RC involve both sea surface temperature and thermocline anomalies which leads to a decreased error propagation compared to the ZC model, where mainly thermocline anomalies dominate the optimal initial perturbations. This reduced error propagation allows the RC to provide a higher skill at long lead times than the deterministic ZC model. [ABSTRACT FROM AUTHOR]

Using a Green's function‐like approach, this study identifies optimal atmospheric heat sources for the two leading modes of South Asian Summer Monsoon (SASM) interannual variability. Optimal heating for the first mode, characterized by a lower‐level anomalous anticyclone over northern Bay of Bengal (BOB), is distributed over the Arabian Sea and tropical eastern Indian Ocean (EIO)‐Maritime Continent, with cooling over the BOB‐western North Pacific. In contrast, heating over the tropical southwestern Indian Ocean and equatorial Atlantic, along with cooling over the tropical EIO‐western Pacific, optimally drives the second mode, featuring an anomalous anticyclone over central‐northern India. El Niño/Southern Oscillation indirectly influences SASM by triggering heat sources resembling these optimal patterns. Other sea surface temperatures (SSTs), like those over equatorial Atlantic, can also generate similar heating structures, causing corresponding SASM anomalies. This suggests that the impact of SST modes on SASM depends on the similarity of induced heat sources to optimal patterns. Plain Language Summary: The principal origins of South Asian summer monsoon (SASM) interannual variability are rooted in the combined modulation of three tropical oceans, which challenges its prediction due to complex multi‐ocean interactions. Atmospheric heat sources, however, can directly impact SASM, acting as a bridge connecting sea surface temperature (SST) and SASM. Here we identify optimal atmospheric heat sources for the two leading modes of SASM interannual variability using a Green's function‐like approach. Optimal heating for the first mode, characterized by a lower‐level anomalous anticyclone over northern Bay of Bengal (BOB), is distributed over the Arabian Sea and the tropical eastern Indian Ocean (EIO)‐Maritime Continent, with cooling over the BOB‐western North Pacific. In contrast, heating over the tropical southwestern Indian Ocean and equatorial Atlantic, along with cooling over the tropical EIO‐western Pacific, optimally drives the second SASM mode, featuring a lower‐level anomalous anticyclone over central‐northern India. El Niño/Southern Oscillation indirectly influences SASM by triggering heat sources resembling these optimal patterns. Other SSTs, such as those over the equatorial Atlantic, can also generate similar heating structures as the optimal heat sources, further impacting corresponding SASM modes. Optimal heat sources provide a possible way to understand the combined effects of different SST modes on SASM. Key Points: Optimal heat sources for the South Asian summer monsoon (SASM) interannual variability are identified using a Green's function‐like methodThe El Niño/Southern Oscillation indirectly impacts SASM by triggering heat sources resembling the optimal patternsOther sea surface temperature anomalies can also generate similar heating structures to the optimal patterns, leading to SASM anomalies [ABSTRACT FROM AUTHOR]

ABSTRACT Climate extreme events are intensifying globally, posing increasing risks across various sectors. Understanding climate extremes' spatiotemporal patterns and responses to climate change is crucial for effective management, especially on a regional scale. This study examines temperature and precipitation extremes, as well as compound dry‐hot events (CDHEs), in the Ishikari River basin (IRB) of Northeastern Japan, an area of significant socioeconomic importance. We focus on spatiotemporal analysis under multiple scenarios of temperature/precipitation extremes and CDHEs based on statistical downscaled datasets from the Coupled Model Intercomparison Project Phase 6. Results indicate that IRB underwent increased trends of extreme hot periods, extreme droughts, and heavy rainfalls during 1985–2014, which are significantly affected by the North Pacific Oscillation and Southern Oscillation Index. Future projections show that warming temperatures and less rainfall shift asymmetrical impacts on temperature and precipitation extremes, expecting increased warm spells and CDHEs but increased wet durations and less heavy rainfalls. Emission scenarios analysis suggests low‐emission scenarios (SSP1‐2.6) could mitigate their exacerbations, especially for CDHEs (decreased by 139%). Moreover, spatial‐pattern analysis reveals regional heterogeneity in temperature and precipitation extremes, with northern mountainous regions more susceptible to thermal extremes and southern plain regions (e.g., Sapporo city) experiencing prolonged drought and CDHEs. This study provides valuable insights into climate risk management and adaptation strategies. [ABSTRACT FROM AUTHOR]

The Eastern South Pacific Right Whale (SRW) (Eubalaena australis) population has gained interest due to its Critically Endangered conservation status. So far, this population has been confirmed only along the coasts of Chile (18°20'S to 56°30'S) and from southern to central Peru (17°38'S to 12°11'S). Recent records have extended the species' known range, highlighting its geographic distribution, now reaching 1500 km north. Here, we report six recent records, consisting of five sightings and one stranding, that expand the documented range to northern Ecuador (0.6°N). The northern extension of the population may be associated with the unusual three-year-long cold phase (La Niña) of the El Niño Southern Oscillation (ENSO) in the eastern South Pacific, population expansion, movement and re-distribution of the species, increased monitoring effort, or a combination of these factors. These observations raise hope for the Critically Endangered SRW population, as the occurrence of mother-calf pairs may indicate a potential for population recovery. Nevertheless, these findings intensify concerns for what is still the least abundant SRW population, underscoring the urgency for more targeted research and conservation measures. [ABSTRACT FROM AUTHOR]

ABSTRACT As global surface temperatures have increased with human‐induced climate change, notable compound climate extremes in the New Zealand (NZ) region associated with atmospheric heatwaves (AHWs) and marine heatwaves (MHWs) have occurred in the past 6 years. Natural modes of variability that also played a key role regionally include the Interdecadal Pacific Oscillation (IPO), El Niño/Southern Oscillation (ENSO) and changes in the location and strength of the westerlies as seen in the Southern Annular Mode (SAM). Along with mean warming of 0.8°C since 1900, a negative phase of the IPO, La Niña phase of ENSO and a strongly positive SAM contributed to five compound warm extremes in the extended austral summer seasons (NDJFM) of 1934/35, 2017/18, 2018/19, 2021/22 and 2022/23. These are the most intense coupled ocean/atmosphere (MHWs/AHWs) heatwaves on record with average temperature anomalies over land and sea +0.8°C to 1.1°C above 1991–2020 averages. The number of days above 25°C and above the 90th percentile of maximum temperature has increased, while the number of nights below 0°C and below the 10th percentile has decreased. Coastal waters around NZ recently experienced their longest MHW in the satellite era (1982‐present) of 289 days through 2023. The estimated recurrence interval reduces from 1 in 300‐years for the AHW event during the 1930s climate to a 1 in 25‐year event for the most recent decade. Consequences include major loss of ice of almost one‐third volume from Southern Alps glaciers from 2017 to 2021 with rapid melt of seasonal snow in all four cases. Above‐average temperatures in the December/January grape flowering period resulted in advances in veraison (the onset of ripening); and higher‐than‐average grape yields in 2022 and 2023 vintages. Marine impacts include widespread sea‐sponge bleaching around northern and southern NZ. [ABSTRACT FROM AUTHOR]

The examination of the spatiotemporal characteristics and developmental trends of drought is crucial for enhancing water resource management, bolstering drought resistance, and improving disaster prevention capabilities. This study employs the Standardized Precipitation Evapotranspiration Index (SPEI) and grain yield data across various time scales, in conjunction with methodologies such as Run Theory, Mann-Kendall, and Standardized Yield Residual Series, to conduct an in-depth investigation into the spatiotemporal variation characteristics of meteorological drought in Hunan Province and its impact on grain yield. The findings suggest that: (1) Since 1960, the likelihood of seasonal drought occurrence in Hunan Province has been ranked as autumn > winter > spring > summer, with mild drought occurring most frequently, followed by moderate drought, while the frequency of severe and extreme drought remains low. (2) Meteorological drought in Hunan Province exhibits spatial differences at the seasonal scale, with the overall drought changes in spring and summer displaying a non-significant upward trend; the western and southern regions exhibit a trend of aridification in autumn; and in winter, the Zhangjiajie and Xiangxi regions show an insignificant downward trend. (3) From 1960 to 2022, grain production in Hunan Province has demonstrated a pattern of fluctuation and increase. The meteorological yield of grain crops displays a high-low-high spatial distribution from south to north. Concurrently, there is a positive correlation between short-term climate change and meteorological output, while long-term climate change is not evident. (4) El Niño Southern Oscillation (ENSO) is a significant circulation factor affecting meteorological drought in Hunan Province, and the meteorological drought in autumn and winter in Hunan Province is significantly influenced by ENSO. The research findings can provide reference significance and a scientific basis for drought research and comprehensive management in Hunan Province, and offer data and theoretical support for promoting economic development. [ABSTRACT FROM AUTHOR]

Numerous studies, spanning experimental, instrumental, historical, and modeled approaches, have delved into understanding climate change across the Holocene era and millennial-scale occurrences. However, the chronology and causes of centennial-scale climate events during the Holocene remain controversial. In this study, we overviewed 10 of the best-resolved and most accurately dated records detailing climate change in the Northern Hemisphere (NH) over the Holocene, obtained from different proxies across different climatic zones, and constructed a stack of temperature changes in the NH. Based on the constructed stack, we identified and categorized 15 notable Holocene centennial cooling events (HCCEs) in the NH (period with temperature decreases). To test the chronological validity of the constructed HCCEs, we compared them with the most accurately dated and highly resolved climate records during the last 3 kyr, which have been extensively investigated by the scientific community. Based on the close alignment of the outlined HCCEs with temperature records, we suggest that other HCCEs also match centennial climate cooling events over the last 10 kyr. To understand the origins of the established HCCEs, we compared them with potential climate influencing factors: total solar irradiance (TSI), explosive volcanic activity, Atlantic meridional overturning circulation (AMOC)-limited slowdowns, Intertropical Convergence Zone (ITCZ) fluctuations, and El Niño/Southern Oscillation (ENSO variability. Early Holocene HCCE 5, terminated by a prominent 8.2-ka cold event, was likely driven by the superposition of the AMOC limited slowdown, TSI minimum, and volcanic activity. The Holocene Thermal Maximum (HTM) happened between HCCEs 5 and 4a and was interrupted by HCCE 4c and 4b, coeval, with a significant southward shift of the ITCZ, likely related to cooling in the tropical zone. However, the sequence of HCCEs 3b, 3a, and 2b (over 4.53–3.42 BP), accompanied by small changes in the TSI, was likely forced by an increase in ENSO variability, leading to remarkable changes in the tropical processes and a southward shift of the ITCZ, coeval with the collapse of the Chinese Neolithic cultures and onset of the Holocene Neoglacial. Subsequent HCCEs 2a–0a were likely forced by the TSI minimum combined with the influence of ENSO and volcanism over the last 2 ka. [ABSTRACT FROM AUTHOR]

ABSTRACT The anomalous variability of extreme cases of the tropical tropopause provides insight into the stratosphere‐troposphere exchange process crucial for understanding climate change. The present study analyses the extreme variability of the tropopause and its thermal structure over the tropics using GPS radio occultation data over the period 2006–2019. The extremely cold and warm tropopauses and extremely high and low tropopauses are identified based on the cold point tropopause temperature and height, respectively, when their values exceed two standard deviations with respect to their climatological means. The analyses revealed frequent occurrence of extreme cases of tropopause over the Atlantic Ocean compared to the Western Pacific Ocean. Individually, extremely warm and low cases occur more frequently over the subtropics, while extremely cold and high cases occur frequently over the deep tropics. These extreme cases pose different thermal structures bounded within the extremely low and high tropopauses throughout the tropics. The height difference between the extremely high and low tropopause cases is wider over the Atlantic Ocean and adjoining areas compared to the western Pacific Ocean. The temperature difference between the extremely warm and cold tropopause cases is higher in the Atlantic, Central Pacific, and Indonesian regions compared to the American, Indian Ocean, and western Pacific Ocean regions. The relationship between the El Niño Southern Oscillation (ENSO) phases and extreme tropopause cases is also investigated which reveals a higher occurrence of extremely high tropopause cases during the El Niño phase while low tropopause cases during the La Niña phase. Our analysis also revealed the thermal patterns of the extreme cases characterising colder and sharper tropopause over the convective regions compared to subsidence regions. [ABSTRACT FROM AUTHOR]

ABSTRACT Global or regional impacts of El Niño Southern Oscillation (ENSO) have predominantly been investigated through the Niño3.4 index, representing the sea surface temperature (SST) variations in the central Tropical Pacific. In this study, we comparatively evaluated the usefulness of Niño1+2, a relatively less utilised index that represents SST variability in the Eastern Tropical Pacific. In our analyses, we focused on ENSO impacts on Euro‐Mediterranean (EM) climate variability during boreal winter, using data from the NCEP/NCAR Reanalysis. The correlation analysis involving Niño1+2 depicts more distinct temperature and precipitation patterns over the EM region. Amongst the SST‐based Niño indices, it has the highest correlation with the East Atlantic index (0.47, statistically significant at > 99% confidence level), a prominent regional teleconnection associated primarily with the strength of the East Atlantic ridge, which produces dipole‐type climate patterns between East Atlantic/Western Europe and Central/Eastern Mediterranean. Moreover, its lagged correlations with the following spring (0.39), summer (0.31), and autumn (0.36) are all statistically significant at ≥ 99% confidence levels. The composite analysis shows that different Niño regions have distinct effects on atmospheric circulation and climate in the EM region. The Niño1+2 index is particularly helpful in identifying the years when warm SST anomalies of El Niño extend to the Eastern Equatorial Pacific, which results in a reversal of temperatures across the EM region. Thus, this study suggests that Niño1+2 is a useful index for studying climate variability and predictability in the EM region, especially when used in conjunction with other Niño indices, as it captures some ENSO features that they may not encompass. [ABSTRACT FROM AUTHOR]

Surface air temperature (SAT) variability is investigated for advancing our understanding of the climate patterns over the Kingdom of Saudi Arabia (KSA). SAT variability reveals significant warming trends, particularly from 1994 onward, as demonstrated by nonlinear and linear trend analysis. This warming is linked to global climate patterns, which serve as significant indicators for studying the effects of climate change on surface air temperature patterns across the KSA. The empirical orthogonal function (EOF) method is employed for analyzing SAT due to its effectiveness in extracting dominant patterns of variability during the winter (DJF) and summer (JJA) seasons. The first mode (EOF1) for both seasons shows positive variability across the KSA, explaining more than 45% of the variance. The second mode (EOF2) indicates negative variability in central and northern regions. The third mode (EOF3) describes positive variability but with lower variance over time. PC1 is used to describe the physical mechanism of SAT variability and correlations with global sea surface temperature (SST). The physical mechanism shows that the variability in Mediterranean troughs during the winter season and high pressure over the Indian Ocean and central Asia controls SAT variability over the KSA. The correlation coefficients (CCs) were calculated during the winter and summer season between the SAT of the KSA and six teleconnection indices, El Niño Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), Atlantic Meridional Mode (AMM), Pacific Warm Pool (PWP), North Atlantic Oscillation (NAO), and Tropical North Atlantic (TNA) SST for the period from 1994 to 2022. ENSO shifts from positive to negative correlations with SAT from winter to summer. IOD shows a diminished correlation with SAT due to the absence of upper air dynamics. PWP consistently enhances surface warming in both seasons through upper air convergence during both seasons. AMM and NAO have a non-significant impact on SAT; however, TNA contributes warming over central and northern parts during winter and summer seasons. The seasonal SAT variations emphasize the significant role of ENSO, PWP, and TNA across the seasons. The findings of this study can be helpful for seasonal predictability in the KSA. [ABSTRACT FROM AUTHOR]

Interdecadal variations, since the middle of the 20th century, in the seasonal cycle of Southern Hemisphere extratropical synoptic scale weather systems, are studied and related to associated anomalies in Southern Australian rainfall over south-west Western Australia (SWWA) and southeast Australia (SEA). A data-driven method is employed in which atmospheric fluctuations, specified from 6-hourly lower-tropospheric reanalysis data, are spectrally analysed in space and time to determine the statistics of the intensity and growth rates of growing and decaying eddies. Extratropical storms, blocking and north-west cloud band weather types are investigated in two frequency bands, with periods less than 4 days and between 4 and 8 days, and in three growth rate and three decay rate bins. Southern Australian rainfall variability is found to be most related to changes in explosive storms particularly in autumn and winter. During the first 10 years of the Australian Millennium Drought (AMD), from 1997 to 2006, dramatic changes in rainfall and storminess occurred. Rainfall declines ensued over SEA in all seasons, associated with corresponding reductions in the intensity of fast-growing storms with periods less than 4 days. These changes, compared with the 20-year timespans of 1949 to 1968 and 1975 to 1994, also took place for the longer duration of 1997 to 2016, apart from summer. Over SWWA, autumn and winter rainfall totals have decreased systematically with time for each of the 10-year and 20-year timespans analysed. Southern Australian rainfall variability is also found to be closely related to the local, hemispheric or global features of the circulation of the atmosphere and oceans that we characterise by indices. Local circulation indices of sea level pressure and 700 hPa zonal winds are good predictors of SWWA and SEA annual rainfall variability particularly in autumn and winter with vertical velocity generally less so. The new Subtropical Atmospheric Jet (SAJ) and the Southern Ocean Regional Dipole (SORD) indices are found to be the most skilful non-local predictors of cool season SWWA rainfall variability on annual and decadal timescales. The Indian Ocean Dipole (IOD) and Southern Oscillation Index (SOI) are the strongest non-local predictors of SEA annual rainfall variability from autumn through to late spring, while on the decadal timescale, different indices dominate for different 3-month periods. [ABSTRACT FROM AUTHOR]

Precipitation and air temperature have decreased and increased, respectively, in the three biomes of the state of Mato Grosso (Amazon - AMZ, Cerrado - CER, and Pantanal - PAN), making them susceptible to increased drought. The objective of this study was to analyze the trends of severity, intensity and duration of drought events between 1970 and 2022, and their relationships with sea surface temperature anomalies (SSTA) and the Southern Oscillation Index (SOI). The Standardized Precipitation Index (SPI) and Standardized Precipitation and Evapotranspiration Index (SPEI) were calculated using precipitation and air temperature data from the ERA5-land product. The trends of the SPI and SPEI were obtained using the Mann-Kendall (MK) test, and the number of occurrences, severity, intensity, and duration were obtained using the Run-Theory method. The results showed that the SPI and SPEI tended to decrease in the three biomes between 1970 and 2022. Moderate, severe and extreme drought events occurred in all biomes, with emphasis on the highest drought severity in the Pantanal between 2019 and 2022. The highest number of occurrences of extreme droughts by the SPI occurred in AMZ and CER between 2020 and 2022, and the highest values of severity, duration and intensity occurred in CER and PAN in the same period. However, the values of severity, duration and intensity by the SPEI occurred in AMZ and CER. The SPI and SPEI had a similar correlation pattern with the SSTA and SOI indices. The SPI had weak negative correlation with the Atlantic Multidecadal Oscillation (AMO), Southern Oscillation Index (SOI), Tropical Northern Atlantic Index (TNAI) and Tropical Southern Atlantic Index (TSAI), while the SPEI had moderate negative correlation with AMO and TSAI. In conclusion, the results of this study showed that the severity of drought in Mato Grosso increased between 1970 and 2022. The severity of drought in the Pantanal was particularly high between 2019 and 2022. SSTA anomalies and the SOI had some influence on the seasonal and interannual dynamics of drought in Mato Grosso, but not all SSTA anomalies had influence. [ABSTRACT FROM AUTHOR]

This paper presents new data derived from pollen, starch and radiocarbon samples that were collected from six Aboriginal earth (oven) mounds and middens on the Calperum and Pike floodplains, Murray-Darling Basin (MDB), South Australia (SA). Analyses of these samples were undertaken in order to enhance our understanding about the Holocene lifeways of Aboriginal people living in this region. The results from these analyses, combined with published data about the mounds' contents, relevant ethno-historical information and climate data, allow us to infer that Aboriginal people adopted, in this region, an innovative food production system about 3800 years ago. Further, we argue that the timing of the change suggests this was in response to adverse El Niño Southern Oscillation (ENSO) related weather patterns and consequently fluctuations in both terrestrial and aquatic food resources. [ABSTRACT FROM AUTHOR]

Recently, the North Tropical Atlantic (NTA) Sea Surface Temperature (SST) anomalies emerge as a key-driver in the biennial transitions of El Niño Southern Oscillation (ENSO) and by extension of the whole ENSO-Indian Summer Monsoon (ISM) system. In this context, we utilized a suite of Coupled Model Intercomparison Project Phase 6 (CMIP6) models with the Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5) and historical simulations to investigate whether the ENSO-ISM teleconnections as well as its biennial signature undergoes significant modulations in the future warming climate as mediated through the NTA SSTs. Our results reveal a pronounced increase in NTA variability under greenhouse warming, associated with an enhanced two-way teleconnection between NTA and ENSO, while the increase of ENSO variability is more modest. There is an exaggerated signature for the previous ENSO SSTs impacting boreal spring NTA SSTs, compared to a modest enhancement in NTA forcing on the following ENSO state. However, intriguingly, this later signature of NTA damping the ENSO variability seems to strengthen steadily from the historical simulation to the SSP5-8.5, implying an enhanced NTA forcing and biennial rhythm in future projections. In consonance with this emerging NTA signal, there is a significant increase in the variability of ISM rainfall by 21st century, together with a modest strengthening of the ENSO-ISM relationships in the future warming scenarios. We also noted consistent future strengthening of a biennial signature in the ENSO-ISM teleconnection. It is further inferred that the Pacific equatorial zonal SST gradient in conjunction with the NTA relative warming act as important sources for the future intensification of this biennial signal in ENSO variability and for the inter-model spread in the projections. In contrast to this, the future intensification in ISM rainfall variability and its biennial signature are not uniquely driven by these factors. [ABSTRACT FROM AUTHOR]

The relationship between the South Asian summer monsoon (SASM) and El Niño Southern Oscillation (ENSO) is crucial for understanding and predicting changes of monsoon rainfall, as water resources strongly affect the living of billions of populations in South Asia. Although many mechanisms have been proposed to understand variations of SASM-ENSO relationship in previous studies, the impact of internal variability and primary control factor are under debate. Here, the potential contribution of internal variability to SASM-ENSO relationship is analyzed by using large-ensemble historical simulations in which members only differ for initial conditions, from two coupled climate models FGOALS-g3 and CESM2. While both ensembles show reasonable skills in monsoon climatology and basic ENSO characteristics, there is considerable spread of SASM-ENSO correlation coefficient across ensemble members: −0.57 to -0.01 (−0.66 to −0.25, range between 5 and 95%) in FGOALS and −0.74 to −0.36 (−0.83 to −0.51) in CESM2 for precipitation (circulation). We find that ENSO intensity is the primary factor significantly influencing the diversity of the SASM-ENSO relationship by modulating the Walker circulation, which is associated with the spread in mean state of tropical Pacific sea surface temperature zonal gradient. The ENSO intensity can explain about 8% and 20% of the spread in the SASM-ENSO relationship in the FGOALS and CESM2 large ensembles, respectively. Taking the mean of 110 and 100 members as a referenced truth, approximately 75 and 60 members are necessary to accurately estimate the SASM-ENSO relationship for FGOALS and CESM2, respectively, affirming the importance of sufficiently large ensemble sizes to reasonably address the interannual SASM-ENSO relationship. [ABSTRACT FROM AUTHOR]

Using a new measure that relates tropical cyclone (TC)-induced sea surface cooling with the strength of TCs, interannual variations in potential impacts of the upper ocean stratification on TC-induced sea surface cooling associated with the evolution of El Niño/Southern Oscillation (ENSO) are investigated in the northwestern Pacific using an ocean reanalysis product, with a special focus on haline effects. It is found that the haline stratification could suppress the sea surface cooling by as much as 20% to the south of 20°N in the peak typhoon season (July-October), and this contribution is different between their developing years (September-October) and decaying years (July-August). More specifically, the haline effects may vary up to 25% (40%) during the decaying years of El Niño (La Niña). Due to anomalous haline effects, the region to the west of 160°E is susceptible to the sea surface cooling during the developing and decaying years of El Niño, while the cooling could be suppressed in this region during the decaying years of La Niña. Although the effects of haline stratification have been found less important than those of thermal stratification, potential impacts of the upper ocean salinity on TC-induced sea surface cooling associated with the ENSO have been quantitatively estimated for the first time. Since the main focus of this paper is to present the new measure and discuss potential impacts of the upper ocean salinity stratification, further verifications need to be conducted once more observational data is accumulated or through numerical simulations. [ABSTRACT FROM AUTHOR]

Thirty years (1993–2022) of concurrent satellite and in‐situ observations show a long‐term strengthening of the equatorial Pacific upper‐ocean circulation. Enhanced southeasterly and cross‐equatorial winds have caused an annual mean, basin‐wide acceleration of the equatorial westward near‐surface currents by ∼20% and an acceleration of poleward flow north (south) of the equator by ∼60% (∼20%). Additional moored velocity data reveal a deepening of the Equatorial Undercurrent (EUC) core at 170°W and significant shoaling at 140°W and 110°W, but no significant changes in EUC core velocity. The strongest subsurface zonal velocity trends are observed above the EUC core in the central to eastern Pacific and occur before and after the seasonal maximum of EUC core velocity, causing enhanced upper‐ocean vertical current shear. Consistent with trends of the 20°C isotherm depth along the equatorial Pacific, a significant basin‐wide steepening of the equatorial thermocline is observed. Both the accelerating equatorial current system and the enhanced thermocline slope are consistent with an observed steepening of the zonal sea surface height gradient due to increased wind‐driven westward mass transport at the surface. During February‐March, both surface and subsurface currents along the equator show eastward velocity trends, in contrast to westward near‐surface current trends during the remainder of the year. The trend reversal is attributed to both a long‐term shift in equatorial Kelvin wave activity and to the impact of strong interannual variability due to El Niño Southern Oscillation and other modes of natural variability on decadal to multidecadal time scales. Plain Language Summary: Thirty years (1993–2022) of temporally overlapping satellite and in‐situ observations reveal a long‐term strengthening of the equatorial Pacific circulation in the upper 200 m. Both the west‐east (zonal) and south‐north (meridional) surface atmospheric winds typically observed in the tropical Pacific intensified. As a result, westward near‐surface currents in the central equatorial Pacific accelerated by ∼20%, while poleward currents accelerated by ∼60% (∼20%) north (south) of the equator. The strongest trends in zonal velocity are observed above the core of the Equatorial Undercurrent. While the subsurface current in the central and eastern Pacific shoaled by 12 m, it deepened in the western Pacific by 6 m, which aligns with trends of the 20°C isotherm depth. Both the accelerating equatorial currents and the steeper thermocline slope are consistent with a steepening west‐east slope of sea surface height due to increased westward water mass transport. Our results show that a shift in equatorial wave activity and strong interannual variability cause eastward velocity anomalies in the observed surface and subsurface current trends during February‐March. Between 1993 and 2022, long‐term equatorial circulation trends persist, but these trends are modified by natural events at both interannual timescales such as El Niño and La Niña events, and longer timescales. Key Points: 30 years of observations show a wind‐driven strengthening of equatorial Pacific surface zonal currents by ∼20% and poleward flow by ∼20%−60%The subsurface Equatorial Undercurrent intensified above its core depth, primarily in the central to eastern PacificLong‐term moored observations of subsurface velocity and temperature show a significant basin‐wide steepening of the equatorial thermocline [ABSTRACT FROM AUTHOR]

In this study we analyse projections of future changes to the El Niño Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), and Southern Annular Mode (SAM) using the latest generation of climate models. Multiple future scenarios are considered. We quantify the fraction of models that project future increases or decreases in the frequency and amplitude of ENSO, IOD, and SAM events in the late 21st century. Changes to the frequency of co‐occurring and consecutive driver phases are also examined. We find that while there is large inter‐model spread, the most common pathways correspond to more frequent ENSO events; weaker, less frequent IOD events; and stronger, but less frequent austral spring SAM events. There is no clear consensus on the change to the frequency of concurrent events, though we find a significant increase in La Niña‐ and El Niño‐only events occurring with neutral IOD and SAM. We also find a significant increase to the frequency of consecutive positive IOD events under a high emissions scenario, but no significant change to the frequency of consecutive ENSO or negative IOD events. In most models, the correlation between drivers, that is, ENSO and IOD, and ENSO and SAM, does not significantly change between the late 20th and late 21st century. These results indicate a high degree of internal variability in the models. Plain Language Summary: Year‐to‐year climate variability impacts ecosystems and billions of people around the world. Major drivers of this variability in the Southern Hemisphere include the El Niño Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), and the Southern Annular Mode (SAM). As anthropogenic activities continue to impact the climate, and further change is inevitable, we need to improve understanding of how these climate drivers will change. Here we use the latest generation of climate models to investigate how the strength and frequency of these three climate drivers are projected to change over the remainder of the 21st century. We investigate changes to these drivers individually, as well as changes to the frequency of these drivers occurring simultaneously or consecutively. While there is still a large amount of inter‐model spread, the most common model projections are: more frequent ENSO events; weaker and less frequent IOD events; and stronger, but less frequent SAM events. A statistically significant increase in the frequency of consecutive positive IOD events in the high emissions scenario is also found. Key Points: Using all available models and ensemble members, the latest generation of climate models project an overall increase to the frequency of El Niño‐Southern Oscillation (ENSO) events but a weakening and decrease in Indian Ocean Dipole (IOD) events in the late 21st century. The Southern Annular Mode (SAM) is also projected to strengthen in austral springThere is less consensus among models on projections of frequency change of concurrent (co‐occurring) climate driver phases and consecutive ENSO and IOD phasesInternal variability remains a large source of uncertainty. Multi‐model mean results can differ markedly depending on the subset of models used [ABSTRACT FROM AUTHOR]

We investigate how seasonal flow variations and a climatic regime that is dominated by the El Niño–Southern Oscillation (ENSO) influence Sb flux dynamics in an Australian river impacted by mining. Sampling (n = 496) spans a hydrologically complex 7‐year period of drought, bushfires and floods from 2016 to 2023, during which 17% of samples exceeded the Sb drinking water guideline concentration (3 μg L−1). Aqueous Sb (SbAq) concentration–discharge (C–Q) relationships are non‐continuous/non‐linear across the flow range, with chemodynamic behaviour at moderate flows reflecting hydrological connection to the primary Sb‐source area combined with variable dilution. In contrast chemostatic behaviour occurred at extreme low and high flows, reflecting hydrological disconnection from the source area and persistent dilution, respectively. SbAq was significantly positively correlated (p < 0.01, Spearman's ρ = 0.58) with a Q index representing the proportional contribution of sub‐catchment flow from the mineral‐field area, suggesting sufficient localised rainfall in the Sb mining‐impacted sub‐catchment contributes to downstream peaks in SbAq concentrations. Aqueous and particulate Sb (SbP) annual loads (La) during the study period spanned 24–5174 and 1.2–2820 kg, respectively and were strongly flow dependant with extreme interannual variability reflecting dry and wet years. We extrapolate daily load‐daily discharge (Ld–Qd) relationships for SbAq and SbP to estimate Ld over a 53‐year period (1970–2023) of continuous Q data (mean total Sb La = 1865 kg ± [SE] 247). Positive correlations between the annual Southern Oscillation Index and both Sb La (p < 0.05) and proportional SbPLa over 53 years suggests ENSO fluctuations influence annual Sb transport dynamics. Upstream SbP load estimates correspond with downstream estimates of coastal floodplain sedimentary Sb mass, with approximately 10%–45% of the estimated SbP exported downstream since approximately 1880 accumulated on the Macleay coastal floodplain. Data suggest at current rates of export, complete flushing‐leaching of mine tailings‐derived Sb from the upper Macleay catchment may take in the order approximately 600–1000 years. [ABSTRACT FROM AUTHOR]

The spatial and temporal distribution of heavy rainfall across the Taihang Mountains exhibits significant variation. Due to the region's unstable geological conditions, frequent heavy rainfall events can lead to secondary disasters such as landslides, debris flows, and floods, thus intensifying both the frequency and severity of extreme events. Understanding the spatiotemporal evolution of heavy rainfall and its response to atmospheric circulation patterns is crucial for effective disaster prevention and mitigation. This study utilized daily precipitation data from 13 meteorological stations in the Taihang Mountains spanning from 1973 to 2022, employing Rotated Empirical Orthogonal Function (REOF), the Mann–Kendall Trend Test, and Continuous Wavelet Transform (CWT) to examine the spatiotemporal characteristics of heavy rainfall and its relationship with large-scale atmospheric circulation patterns. The results reveal that: (1) Heavy rainfall in the Taihang Mountains can be categorized into six distinct regions, each demonstrating significant spatial heterogeneity. Region I, situated in the transition zone between the plains and mountains, experiences increased rainfall due to orographic lifting, while Region IV, located in the southeast, receives the highest rainfall, driven primarily by monsoon lifting. Conversely, Regions III and VI receive comparatively less precipitation, with Region VI, located in the northern hilly area, experiencing the lowest rainfall. (2) Over the past 50 years, all regions have experienced an upward trend in heavy rainfall, with Region II showing a notable increase at a rate of 14.4 mm per decade, a trend closely linked to the intensification of the hydrological cycle driven by global warming. (3) The CWT results reveal significant 2–3-year periodic fluctuations in rainfall across all regions, aligning with the quasi-biennial oscillation (QBO) characteristic of the East Asian summer monsoon, offering valuable insights for future climate predictions. (4) Correlation and wavelet coherence analyses indicate that rainfall in Regions II, III, and IV is positively correlated with the Southern Oscillation Index (SOI) and the Pacific Warm Pool (PWP), while showing a negative correlation with the Pacific Decadal Oscillation (PDO). Rainfall in Region I is negatively correlated with the Indian Ocean Dipole (IOD). These climatic factors exhibit a lag effect on rainfall patterns. Incorporating these climatic factors into future rainfall prediction models is expected to enhance forecast accuracy. This study integrates REOF analysis with large-scale circulation patterns to uncover the complex spatiotemporal relationships between heavy rainfall and climatic drivers, offering new insights into improving heavy rainfall event forecasting in the Taihang Mountains. The complex topography of the Taihang Mountains, combined with unstable geological conditions, leads to uneven spatial distribution of heavy rainfall, which can easily trigger secondary disasters such as landslides, debris flows, and floods. This, in turn, further increases the frequency and severity of extreme events. [ABSTRACT FROM AUTHOR]

Polar sea surface height observation by radar altimeters requires missions with high-latitude orbit and specific processing to observe the sea-ice-covered region within fractures in the ice. Here, we combine sea surface height estimates from different radar satellites over the ice-free and ice-covered polar oceans to create cross-calibrated along-tracks and gridded products over the Arctic Ocean (2011-2021) and the Southern Ocean (2013-2021). The sea surface height from our regional polar products is in great agreement with tide gauges and bottom pressure recorders at monthly timescales in seasonally to year-round icecovered regions. Thanks to the use of several missions and the mapping strategy, our multi-mission products have a greater resolution than monomission products. Part of the sea level variability of the Arctic Ocean product is related to the Arctic Oscillation atmospheric circulation. At long term, the Arctic altimetry sea level is coherent with in-situ steric height evolution in the Beaufort gyre, and negative sea level trends over the 10-year period are observed in the East Siberian slope region, which may be related to the local freshwater decrease observed by other studies. Our regional polar sea level products are limited by current understanding of the sea-ice lead measurements, and homogenization of these polar products with global sea level products needs to be tackled. [ABSTRACT FROM AUTHOR]

In this study, the relationship between large-scale climatic drivers and streamflow of the Chalakudy River Basin, Kerala, was analysed using methods such as bivariate wavelet coherence (BWC), multiple wavelet coherence (MWC), and partial wavelet coherence (PWC) analysis. The four prominent global climate indices chosen are the Indian Ocean Dipole (IOD), North Atlantic Oscillation (NAO), El Niño Southern Oscillation (ENSO), and Pacific Decadal Oscillation (PDO), along with other local climate drivers. The BWC analysis showed that streamflow and rainfall had a very strong in-phase relationship, whereas the maximum temperature and average temperature showed an anti-phase relationship. In the case of global climate drivers, ENSO has a significant impact on the streamflow of the Chalakudy River Basin. The average wavelet coherence (AWC), which quantifies the teleconnections, confirms the observation with a high coherency of 0.75 between streamflow and rainfall and 0.51 for streamflow and ENSO. Streamflow prediction models were developed using random forest (RF) and artificial neural network (ANN) techniques by considering the influence of significant global and local climatic drivers. It was observed that the RF model performed slightly better than the ANN model, with R = 0.875, NSE = 0.766, RMSE = 23.468, and RSR = 0.524. [ABSTRACT FROM AUTHOR]

Ice core oxygen isotope (δ18O) records from low-latitude regions preserve high-resolution climate records in the past, yet the interpretation of these ice core δ18O records is still facing difficulty due to the uncertainty of ice core dating. Here we present a new established δ18O time series from Qiangtang (QT) No. 1 ice core retrieved from the central Tibetan Plateau. Due to the vague seasonal signals in the QT ice core, we investigated the spectral properties of δ18O record with depth and discussed the implications of significant spectral power peaks in the QT ice core. We employed a variational mode decomposition (VMD) analysis for the upper part of the QT ice core to decompose the δ18O depth series in order to separate the El Niño Southern Oscillation (ENSO) mode, a signal strongly preserved in the QT ice core δ18O record. With this approach, we established a time series of 335 years (1677–2011 CE) for the upper 50 m of the QT ice core. Subsequently, we examined the frequency of the new established δ18O time series and detected strong signals of the bidecadal and multidecadal modes of Pacific Decadal Oscillation (PDO). The PDO consists of two modes with periods of approximately 25–35 years and 50–70 years, and we found that the 50–70 years periodicity has persisted since 1700 CE, succeeded by dominance of the 25–75 years periodicity after 1900 CE. Additionally, we analyzed the δ18O series of the QT ice core during the past century and determined that the increasing frequency of El Niño events is an important factor contributing to the increase in recent ice core δ18O. [ABSTRACT FROM AUTHOR]

Several recent high intensity ENSO events have caused strong negative impacts on the adult phases of foundational species in coral reef ecosystems, but comparatively little is known about how climatic variables related to recent ENSOs are impacting the supply of larvae to benthic populations. In marine fishes and invertebrates, reproductive adults and planktonic larvae are generally more sensitive to environmental variability than older, non-reproductive adults. Further, the transport of larvae in ocean currents may also be strongly ENSO dependent. The interactions between the dynamics of larval survivorship and larval transport could lead to population bottlenecks as stronger ENSO events become more common. We tested the predictions of this hypothesis around the Main Hawaiian Islands (MHI) by constructing a correlation matrix of physical and biological time series variables that spanned 11 years (2007–2017) and multiple ENSO events. Our correlation matrix included four types of variables: i. published ENSO indices, ii. satellite-derived sea surface temperature (SST) and chlorophyll variables, iii. abundance and diversity of larval fishes sampled during the late winter spawning season off Oahu, and iv. abundance and diversity of coral reef fish recruits sampled on the western shore of the Big Island of Hawaii. We found that the abundance and diversity of larval fishes was negatively correlated with the Multivariate El Niño Index (MEI), and that larval variables were positively correlated with measures of fall recruitment (September & November), but not correlated with spring-summer recruitment (May & July). In the MHI, SST variables were not correlated with the MEI, but two successive El Niño events of 2014–15 and 2015–2016 were characterized by SST maxima approaching 30°C. Two large pulses of benthic recruitment occurred in the 2009 and 2014 recruitment seasons, with > 8000 recruits observed by divers over the summer and fall months. Both events were characterized by either neutral or negative MEI indices measured during the preceding winter months. These patterns suggest that La Niña and the neutral phases of the ENSO cycle are generally favorable for adult reproduction and larval development in the spring and summer, while El Niño phases may limit recruitment in the late summer and fall. We hypothesize that episodic recruitment during non-El Niño phases is related to favorable survivorship and transport dynamics that are associated with the formation of pairs of anticyclonic and cyclonic eddies on the leeward sides (western shores) of the Main Hawaiian Islands. [ABSTRACT FROM AUTHOR]

Rainfall interception loss (Ei) is a difficult to study and poorly understood flux compared to transpiration and soil evaporation. The influence of climate and vegetation on Ei is not well known at continental‐to‐global and annual‐to‐decadal scales. Here, we use a long‐term multi‐product approach to examine the global trends in Ei, and further utilize a recently developed and validated dataset to isolate the relative contributions of precipitation, vegetation and evaporative demand. At decadal timescales, increasing Ei is largely driven by global vegetation greening through an increase in the intercepting surface and storage capacity, while its inter‐annual variations are mainly controlled by changes in precipitation, largely related to El Niño/Southern Oscillation. Increasing evaporative demand, driven by atmospheric warming, also positively contributes to the global rise in Ei. This study provides new perspectives for further understanding the impacts of climate change on the terrestrial hydrological cycle. Plain Language Summary: Rainfall interception loss is the volume of rain that gets caught by plants before reaching the ground and evaporated back into the atmosphere. It is among the least understood components of the global water cycle. In our research, we used satellite data over a long time (from 1981 to 2020) and a recently developed global model to study how rainfall interception has changed in time and space. We discovered that globally, more rain is being caught by vegetation over the years. This increase happens because our planet is greening, increasing the surface over which rain can be intercepted. On the other hand, changes in how much it rains dominate the year‐to‐year differences in interception loss. At the same time, as the atmosphere gets warmer, water can evaporate faster from vegetation, which adds to the growing trend in interception loss. These results match with the expectation of an intensified water cycle over the continents. Key Points: Rainfall interception loss exhibits increasing trends globallyIts multi‐decadal trends are driven by vegetation greening and warming, whereas interannual variations are controlled by precipitationENSO regulates rainfall interception loss largely through its influence on precipitation dynamics [ABSTRACT FROM AUTHOR]

In this study, we aim to reconstruct southern India's intrinsic environmental changes over the past 1500 years from 3330 to 1830 cal BP by investigating the sedimentation and weathering dynamics in Lake Shantisagara, one of Karnataka's largest lakes. Four distinct climatic phases were delineated based on sedimentological, geochemical, and End Member Modelling Analysis (EMMA) results. Phase 1 (3330-3100 cal BP) is a short-term low rainfall zone characterized by a calm hydrodynamic environment and weak chemical weathering. Phase 2 (3100-2800 cal BP) is a climatically unstable phase, fluctuating between low and high rainfall conditions. Phase 3 (2800-2200 cal BP) is characterized by a stable, low rainfall climate with weak fluvial activity and chemical weathering. It is followed by a highly unstable phase marked by frequent extreme climatic events (Phase 4; 2200-1830 cal BP). Our study reveals a highly unstable hydrodynamic condition that culminated in potentially catastrophic high rainfall events that triggered intense and frequent floods in southern India around ∼2208, 2054, 1958, and 1891 cal BP. Comparative studies of regional records show that the regional climate pattern is similar. There is a strong effect of Total Solar Irradiance (TSI), Sea Surface Temperature (SST) off the Malabar coast, location of the Intertropical Convergence Zone (ITCZ), and the El Niño Southern Oscillation (ENSO) on the monsoon system in southern India. This suggests that there is a global teleconnection. [ABSTRACT FROM AUTHOR]

The electromagnetic waves in the Schumann resonance (SR) frequency range (<100 Hz) radiated by natural "lightning antennas" excite the Earth‐ionosphere cavity confined between the Earth's surface and the lower ionosphere. The peak frequencies of SR are known to vary with source‐observer distance (SOD), while the daily frequency range (DFR: fmax − fmin) is also indicative of the average size of thunderstorm regions. This paper provides observational evidence for these relationships based on SR frequency observations of the vertical electric (EZ) field component at Nagycenk (NCK), Hungary in Central Europe from the period 1994–2015. Variations of the peak frequencies are considered on the annual, seasonal and diurnal time scales as well as during a specific event when squall‐line formation of lightning activity in South America moves toward NCK. DFR is studied in relation to the El Niño Southern Oscillation (ENSO). Increasing area of lightning activity in mid‐high Northern hemisphere latitudes has been identified by DFR variations during the transition from warm to cold episodes of the ENSO in 1998 and 2010. The extension of the lightning area is considered as a consequence of energy released in the tropics and exported to higher latitudes with some months of delay from the end of the El Niño episodes. The frequency variations are interpreted via model calculations and supported with satellite‐based optical lightning observations (Optical Transient Detector, Geostationary Lightning Mapper). The described variations of SR peak frequencies and DFR yield information on the global/regional lightning dynamics and on this basis they have important application to climate issues as well. Plain Language Summary: Schumann resonances (SR) are global electromagnetic resonances maintained by global lightning activity in the cavity resonator formed by the Earth's surface and the lower ionosphere. This paper provides observational evidence for the relationships between the variations of SR peak frequencies of the first three resonance modes and the global/regional lightning dynamics on different time scales based on SR observations of the vertical electric (EZ) field component. As lightning is one of the essential climate variables that provides valuable information on the state of the atmosphere, the lightning source‐observer distance and lightning area‐dependent frequency variations demonstrated in this paper have important applications to climate issues as well. Key Points: Schumann resonance (SR) frequency variations of the EZ field component at nodal distances can be used to study global lightning dynamics at different time scalesThe movement of individual squall‐line formations in South America can cause detectable variations in SR peak frequency at NCK, HungaryExtratropical extension of global lightning activity is revealed during the transition from warm to cold phases of the El Niño Southern Oscillation [ABSTRACT FROM AUTHOR]

Studies have analyzed U.S. tornado variability and correlated F1–F5 tornado occurrence with various natural climate oscillations and anthropogenic factors. Using a relatively new empirical mode decommission (EMD) method that extracts time-frequency modes adaptively without priori assumptions like traditional time-series analysis methods, this study decomposes U.S. tornado variability during 1954–2022 into intrinsic modes on specific temporal scales. Correlating the intrinsic mode functions (IMFs) of EMD with climate indices found that 1. the U.S. overall tornado count is negatively (positively) correlated with the Atlantic Multidecadal Oscillation (AMO) index (the Southern Oscillation Index (SOI)); 2. the negative (positive) correlation tends to be more prevalent in the western (eastern) U.S.; 3. the increase in weak (F1–F2) and decrease in strong (F3–F5) tornadoes after around 2000, when both the AMO and the Pacific Decadal Oscillation (PDO) shifted phases, are likely related to their secular trends and low-frequency IMFs; and 4. the emerging Dixie Tornado Alley coincides with an amplifying intrinsic mode of the SOI that correlates positively with the eastern U.S. and Dixie Alley tornadoes. The long-term persistence of these climate indices can offer potential guidance for future planning for tornado hazards. [ABSTRACT FROM AUTHOR]

Statistical descriptions of extreme met-ocean conditions are essential for the safe and reliable design and operation of structures in marine environments. The significant wave height ( H S ) is one of the most essential wave parameters for coastal and offshore structural design. Recent studies have reported that a time-varying component exists globally in the H S . Therefore, the non-stationary behavior of an annual maximum series of H S is important for various ocean engineering applications. This study aims to analyze the frequency of H S over the northern Indian Ocean by modeling the non-stationarity in the H S series using a non-stationary Generalized Extreme Value (GEV) distribution. The hourly maximum H S data (with a spatial resolution of 0.5° longitude × 0.5° latitude) collected from the global atmospheric reanalysis dataset of the European Centre for Medium-Range Weather Forecasts (ECMWF) is used for the study. To model the annual maximum series of H S using a non-stationary GEV distribution, two physical covariates (El-Ni n ~ o Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD)) and time covariates are introduced into the location and scale parameters of the GEV distribution. The return levels of various frequencies of H S are estimated under non-stationary conditions. From the results, average increases of 13.46%, 13.66%, 13.85%, and 14.02% are observed over the study area for the 25-year, 50-year, 100-year, and 200-year return periods, respectively. A maximum percentage decrease of 33.3% and a percentage increase of 167% are observed in the return levels of various return periods. The changes in the non-stationary return levels over time highlight the importance of modeling the non-stationarity in H S . [ABSTRACT FROM AUTHOR]

In the last four decades of the 20th century, the world rice market was highly unstable, with price volatility greater than that on world wheat and maize markets. In the 21st century, however, new dynamics (a thicker world rice market, more irrigation, milder export restrictions) have contributed to a reduction in price volatility that is now lower than that on world wheat and maize markets. In addition, the El Niño events that are responsible for many shocks to the world rice market are largely predictable several months in advance. The reduced volatility on the world rice market and the predictability of El Niño events make it easier to use international trade as an instrument for food security. The recent experience with rice trade liberalization by Asian rice importers has been largely positive, helping to improve food security and the affordability of healthy diets, with little impact on domestic price volatility. [ABSTRACT FROM AUTHOR]

This study aimed to analyse the temporal and spatial characteristics of drought in the Mekong Delta region. The influence of Sea Surface Temperature Anomalies (SSTAs) and the Southern Oscillation Index (SOI) in the Pacific and Indian Oceans on drought was also investigated. The drought was calculated using the Standardized Precipitation Index (SPI) and the Standardized Precipitation and Evapotranspiration Index (SPEI) indices at one-month and three-month timescales, respectively. A correlation equation is used to determine the relationships between the SSTA/SOI and the SPI/SPEI. The results showed that drought occurred in several months from 1990–1991, 1992–1993, 1995, 1998, 2002–2003, 2005–2006, 2010–2011, and 2015–2016, consistent with the occurrence of drought in the Mekong Delta. However, the SPEI3 reflected drought events more accurately than the other indices. The El Nino phenomenon had a relatively significant impact on drought in the study area. When an El Nino occurred, drought in the Mekong Delta lasted several months but often occurred later than the El Nino. Examining the relationships between the SSTA/SOI and the SPI/SPEI, we find that when the SST increases in the Nino 3.4 region, the NinoW decreases, and a negative SOI affects all drought events. Particularly when the SST increases in the Nino 3.4 region, there is a high probability of drought occurrence in the Mekong Delta. However, drought occurrence is typically 2 to 3 months later than the El Nino. The results will help managers find appropriate solutions to minimize the effects of drought on the research area. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive analysis on the variations in the tropical cyclone (TC) frequencies during 1980–2021, including the linear trends, periodicities, and their variabilities on both global and basin-wise scales. An increasing trend in the annual number of global TCs is identified, with a significant rising trend in the numbers of tropical storms (maximum sustained wind 35   k t s ≤ U m a x < 64   k t s ) and intense typhoons ( U m a x ≥ 96   k t s ) and a deceasing trend for weak typhoons ( 64   k t s ≤ U m a x < 96   k t s ). There is no statistically significant trend shown in the global Accumulated Cyclone Energy (ACE). On a regional scale, the Western North Pacific (WNP) and Eastern North Pacific (ENP) are the regions of the first- and second-largest numbers of TCs, respectively, while the increased TC activity in the North Atlantic (NA) contributes the most to the global increase in TCs. It is revealed in the wavelet transformation for periodicity analysis that the variations in the annual number of TCs with different intensities mostly show an inter-annual period of 3–7 years and an inter-decadal one of 10–13 years. The inter-annual and inter-decadal periods are consistent with those in the ENSO-related ocean drivers (via the Niño 3.4 index), Southern Oscillation Index (SOI), and Inter-decadal Pacific Oscillation (IPO) index. The inter-decadal variation in 10–13 years is also observed in the North Atlantic Oscillation (NAO) index. The Tropical North Atlantic (TNA) index and Atlantic Multi-decadal Oscillation (AMO) index, on the other hand, present the same inter-annual period of 7–10 years as that in the frequencies of all the named TCs in the NA. Further, the correlations between TC frequencies and ocean drivers are also quantified using the Pearson correlation coefficient. These findings contribute to an enhanced understanding of TC activity, thereby facilitating efforts to predict particular TC activity and mitigate the inflicted damage. [ABSTRACT FROM AUTHOR]

This study investigated the sociological dimensions informing public perceptions of water scarcity during the El Niño drought period in Colombia. We conducted this study in Santa Marta, Colombia, and surveyed 405 urban and rural residents to understand their perceptions of water scarcity, management, and the impacts of the El Niño phenomenon. The survey used a Likert scale to measure responses and employed a multivariate analysis of variance to analyze the data while considering factors such as location (urban versus rural) and gender. The study results indicated that urban residents often experience an irregular water supply all year, whereas most rural respondents noted a more consistent availability of water. The perception of water scarcity also differed notably between urban and rural areas due to their different historical and cultural experiences (habitus). Urban respondents mostly recognized the presence of water, while rural perspectives were less conclusive, likely influenced by their direct access to natural water sources. Participants across various demographics consistently reported that poor management by local, regional, and national governments contributes to the water scarcity crisis, highlighting the importance of improving communication about climate events like El Niño and water management to increase community engagement in public policies. Our research suggests that better understanding the social foundations of such perceptions using Bourdieu's concepts of social fields, habitus, and capital forms can significantly enhance water management strategies. [ABSTRACT FROM AUTHOR]

This paper uses time-varying smooth transition autoregressive model to investigate the asymmetric nature of El Niño Southern Oscillation (ENSO) —an exogenous climatic factor—with respect to the nonlinear dynamics of food prices in sub-Saharan Africa. Curating food price series from more than 1100 markets from 36 SSA countries, the study finds that ENSO (linearly or nonlinearly) affects roughly half of food prices considered, with most nonlinear models exhibiting strong asymmetric properties with shock-inflicted persistence. Moreover, in terms of the location of the burden of ENSO impact, I find a geographical and food product divide. Specifically, ENSO appears to be more efficacious on maize prices in Southern, Eastern, and some parts of Central Africa. Conversely, local rice, cassava, millet, and animal products are least affected. The policy implication of this dichotomy is that response to ENSO news should be subregion-specific rather than region-specific, depending on how the subregions absorb the shock. [ABSTRACT FROM AUTHOR]

The influences of the tropical Indian and Atlantic oceans on the development of El Niño Southern Oscillation (ENSO), especially regarding super El Niño events, have been a subject of debate. In particular, several studies argue that these cross-basin influences may be mere statistical artifacts resulting from the high auto-correlation of ENSO. To clarify this issue, we conduct a series of perfect model hindcast experiments to untangle the individual and synergistic effects of the tropical Indian and Atlantic oceans. Our results clearly demonstrate that without these cross-basin effects, the Pacific warming would rarely reach super El Niño level. Specifically, the individual effect of the Indian Ocean efficiently enhances the development of super El Niño events. In contrast, the Atlantic's effect is initially limited because it fails to establish the Bjerknes feedback in the Pacific. However, when coupled with the Indian Ocean, the Atlantic's effect becomes more pronounced as it is amplified by the Bjerknes feedback established by the Indian Ocean. [ABSTRACT FROM AUTHOR]

Climate changes caused by the El Niño oscillation southern (ENSO) significantly influence human diseases, because they are related to anomalies in precipitation or periods of drought. The aims of this paper are: to evaluate the anomalies of the average sea surface temperature, to calculate the average sea surface temperature of the Niño and Niño 1+2 regions, to contextualize infectious pathologies according to their classification: viral, bacterial, parasitic and caused by fungi in the geographical areas or countries of the Region where they have been studied in the historical context (1982-1983; 1997-1998 and 2016-2017) periods of the ENSO considered strong. A bibliographic, descriptive, documentary, retrospective and cross-sectional review was carried out during the months of October 2023 to March 2024. Sea Surface Temperatures (SST) are higher than average, observed throughout the equatorial Pacific Ocean, with anomalies being greater in the central and central-eastern Pacific. For ENSO 2023-2024, in the Niño 4 region the last calculated values of the Niño index remained at a temperature of +1.4 °C, in the Niño 3,4 region it was +1.9, in the Niño -3 region it was +2.0 °C while in the Niño-1+2 regions it weakened to +1.0 °C. The highest incidence and prevalence of ENSO infection (1997-1998) in Ecuador stands out, accounting for an increase in 13 infectious pathologies. Attention must be paid and the links between the environment and the risk of infection must be better understood. [ABSTRACT FROM AUTHOR]

Aim: This study investigates the biogeographic patterns of Pacific white‐sided dolphins (Lagenorhynchus obliquidens) in the Eastern North Pacific based on long‐term passive acoustic records. We aim to elucidate the ecological and behavioural significance of distinct echolocation click types and their implications for population delineation, geographic distribution, environmental adaptation and management. Location: Eastern North Pacific Ocean. Time Period: 2005–2021. Major Taxa Studied: Pacific white‐sided dolphin. Methods: Over 50 cumulative years of passive acoustic monitoring (PAM) data from 14 locations were analyzed using a deep neural network to classify two distinct Pacific white‐sided dolphin echolocation click types. The study assessed spatial, diel, seasonal and interannual patterns of the two click types, correlating them with major environmental drivers such as the El Niño Southern Oscillation and the North Pacific Gyre Oscillation, and modeling long‐term spatial‐seasonal patterns. Results: Distinct spatial, diel and seasonal patterns were observed for each click type. Significant biogeographical shifts in presence were observed following the 2014–2016 marine heatwave event. Main Conclusions: Distinct spatial distributions of the two click types support the hypothesis that Pacific white‐sided dolphins produce population‐specific echolocation clicks. Seasonal and diel patterns suggest spatiotemporal niche partitioning between the populations in Southern California. Interannual changes, notably initiated during the 2014–2016 marine heatwave, indicate climate‐driven range expansions and contractions related to gradual tropicalization of the Southern California Bight. [ABSTRACT FROM AUTHOR]

Indonesia's marine resources are abundant, with fishing being a primary focus. The effective management of these resources requires an understanding of the factors that influence them, such as sea surface temperature (SST), El Niño-Southern Oscillation (ENSO) as indicated by the Southern Oscillation Index (SOI), and chlorophyll-a levels as food sources. This research aimed to elucidate the relationships among those factors at Madura Strait by utilizing their characteristics in response to the electromagnetic wavelengths that can be found Landsat 9 OLI/TIRS satellite images. This research utilized the satellite's Thermal Infrared Sensor (or Band 10) (10.6-11.19 µm) to obtain the SST levels as well as the OceanColor 2 (OC2) algorithm to process Band 2 (0.45-0.51 µm) and Band 3 (0.53-0.59 µm) in order to obtain the chlorophyll-a levels. The results were the mean values of the SST (21.42 and 20.60°C) and the chlorophyll-a levels (0.77 and 0.87 mg/m³) from the periods of June through August 2 022 and December 2 022 through February 2023, respectively. Furthermore, a correlation test and t-test were conducted, which indicated that the chlorophyll-a levels were contradictory with the SST, SOI, and total pelagic fish catches (which were in alignment). The t-test results only indicated significant correlations between the SST and chlorophyll-a levels (-0.806) and between the SST and SOI (0.732), while the other correlation was not significant. [ABSTRACT FROM AUTHOR]

The Nile Basin has long been the subject of extensive research, reflecting its importance, which spans from its historical role in the development of ancient civilizations to its current significance in supporting rapidly changing socioeconomic conditions of the basin countries. This review synthesizes studies focusing on the past and future climate, hydrologic, and drought outlooks of the basin, and explores the roles played by large-scale atmospheric phenomena and water infrastructure on the basin's climate and hydrology. Overall, the studies underscore the complexity of the Nile hydrological system and the necessity for improved modeling and data integration. This review serves as a guide to areas warranting further research by highlighting the uncertainties and inconsistencies among the different studies. It underscores the interconnectedness of climatic and hydrological processes in the basin and encourages the use of diverse data sources to address the data scarcity issue and ensemble models to reduce modeling uncertainty in future research. By summarizing the data and modeling resources employed in these studies, this review also provides a valuable resource for future modeling efforts to understand and explore of the basin's complex climatic and hydrological dynamics. [ABSTRACT FROM AUTHOR]

In recent years, extreme climate events have shown to be occurring more frequently. As a highly populated area in central China, the Jialing River Basin (JRB) should be more deeply explored for its patterns and associations with climatic factors. In this study, based on the daily precipitation and atmospheric temperature datasets from 29 meteorological stations in JRB and its vicinity from 1960 to 2020, 10 extreme indices (6 extreme precipitation indices and 4 extreme temperature indices) were calculated. The spatial and temporal variations of extreme precipitation and atmospheric temperature were analyzed using Mann–Kendall analysis, to explore the correlation between the atmospheric circulation patterns and extreme indices from linear and nonlinear perspectives via Pearson correlation analysis and wavelet coherence analysis (WTC), respectively. Results revealed that among the six selected extreme precipitation indices, the Continuous Dry Days (CDD) and Continuous Wetness Days (CWD) showed a decreasing trend, and the extreme precipitation tended to be shorter in calendar time, while the other four extreme precipitation indices showed an increasing trend, and the intensity of precipitation and rainfall in the JRB were frequent. As for the four extreme temperature indices, except for TN10p, which showed a significant decreasing trend, the other three indices showed a significant increasing trend, and the number of low-temperature days in JRB decreased significantly, the duration of high temperature increased, and the basin was warming continuously. Spatially, the spatial variation of extreme precipitation indices is more obvious, with decreasing stations mostly located in the western and northern regions, and increasing stations mostly located in the southern and northeastern regions, which makes the precipitation more regionalized. Linearly, most of the stations in the extreme atmospheric temperature index, except TN10p, show an increasing trend and the significance is more obvious. Except for the Southern Oscillation Index (SOI), other atmospheric circulation patterns have linear correlations with the extreme indices, and the Arctic Oscillation (AO) has the strongest significance with the CDD. Nonlinearly, NINO3.4, Pacific Decadal Oscillation (PDO), and SOI are not the main circulation patterns dominating the changes of TN90p, and average daily precipitation intensity (SDII), maximum daily precipitation amount (RX1day), and maximum precipitation in 5 days (Rx5day) were most clearly associated with atmospheric circulation patterns. This also confirms that atmospheric circulation patterns and climate tend not to have a single linear relationship, but are governed by more complex response mechanisms. This study aims to help the relevant decision-making authorities to cope with the more frequent extreme climate events in JRB, and also provides a reference for predicting flood, drought and waterlogging risks. [ABSTRACT FROM AUTHOR]

A comprehensive analysis was carried out to investigate the driving factors and influencing mechanisms of spatiotemporal variation of sea level at multiple scales in the East China Sea (ECS) via satellite altimetry datasets from 1993 to 2020. Based on the altimetry grid data processed by the local mean decomposition method, the spatiotemporal changes of ECS sea level are analyzed from the multi-scale perspective in terms of multi-year, seasonal, interannual, and multi-modal scales. The results revealed that the ECS regional mean sea level change rate is 3.41 ± 0.58 mm/year over the 28-year period. On the seasonal scale, the regional mean sea level change rates are 3.45 ± 0.66 mm/year, 3.35 ± 0.60 mm/year, 3.39 ± 0.71 mm/year, and 3.57 ± 0.75 mm/year, for the four seasons (i.e., spring, summer, autumn, and winter) respectively. The spatial distribution analysis showed that ECS sea level changes are most pronounced in coastal areas. The northeast sea area of Taiwan and the edge of the East China Sea shelf are important areas of mesoscale eddy activity, which have an important impact on regional sea level change. The ECS seasonal sea level change is mainly affected by monsoons, precipitation, and temperature changes. The spatial distribution analysis indicated that the impact factors, including seawater thermal expansion, monsoons, ENSO, and the Kuroshio Current, dominated the ECS seasonal sea level change. Additionally, the ENSO and Kuroshio Current collectively affect the spatial distribution characteristics. Additionally, the empirical orthogonal function was employed to analyze the three modes of ECS regional sea level change, with the first three modes contributing 26.37%, 12.32%, and 10.47%, respectively. Spatially, the first mode mainly corresponds to ENSO index, whereas the second and third modes are linked to seasonal factors, and exhibit antiphase effects. The analyzed correlations between the ECS sea level change and southern oscillation index (SOI), revealed the consistent spatial characteristics between the regions affected by ENSO and those by the Kuroshio Current. [ABSTRACT FROM AUTHOR]