Extreme climate events(e.g.,heatwaves and droughts)are becoming increasingly frequent due to global climate change,which inevitably affects tree growth and various other ecological processes.While the impacts of droug...Extreme climate events(e.g.,heatwaves and droughts)are becoming increasingly frequent due to global climate change,which inevitably affects tree growth and various other ecological processes.While the impacts of droughts on these processes have been widely evaluated,the effects of heatwaves on tree growth and soil water content(SWC)remain poorly understood,particularly those related to thinning treatment.In this study,we evaluated the impacts of the 2021 Pacific Northwest Heatwave and thinning on forest growth and SWC,as well as assessed how thinning might mitigate the heatwave's impacts in lodgepole pine forests in British Columbia,Canada.We measured meteorological data(air temperature,rainfall,solar radiation(SR),relative humidity(RH),and wind speed(W_(s)),sap flow,SWC,soil temperature(T_(s)),and tree diameters at the breast height(DBH)during the growing season(June–September)in the control(27,000 stems·ha^(-1)),lightly thinned(4,500 stems·ha^(-1)),and heavily thinned(1,100 stems·ha^(-1))experimental plots from 2018 to 2024.We found that thinning persistently and significantly(p<0.05)increased individual tree growth,with the most pronounced effects in the heavily thinned stands.The 2021 Pacific Northwest Heatwave led to an exceptionally hot growing season,significantly(p<0.05)reducing forest growth and SWC across all plots.Forest growth recovered in 2022 in the thinned plots but remained suppressed in the unthinned plots,suggesting that thinning effectively mitigated the impact of the heatwave on forest growth,while the heatwave's impacts were persistent in the unthinned plots.Our study highlights that thinning is a practical management strategy for improving tree growth and supporting climate change adaptation to extreme climate events.展开更多
Marine heatwaves(MHWs)in the South China Sea(SCS)significantly impact marine ecosystems and socioeconomic development,yet accurately forecasting MHWs remains a challenge.This study developed an upper-ocean temperature...Marine heatwaves(MHWs)in the South China Sea(SCS)significantly impact marine ecosystems and socioeconomic development,yet accurately forecasting MHWs remains a challenge.This study developed an upper-ocean temperature forecasting model based on ConvLSTM for the northern SCS and,in conjunction with the ocean forecasting system LICOM Forecast System(LFS),constructed a hybrid Fusion model using Wasserstein-Distance optimization.The ability of these three models to forecast key MHW metrics with a 10-day lead was assessed during the summer of 2022 in the SCS.Overall,the Fusion model takes advantage of LFS and ConvLSTM,providing superior forecasts for both the duration and intensity of MHWs in the southern SCS.LFS(ConvLSTM)overestimates(underestimates)the duration of MHWs and all models exhibit limitations in forecasting the intensity of MHWs in part of the SCS.The Fusion model's superior forecast skill for MHWs may be attributable to its more realistic representation of the upper-ocean thermal structure with shallower mixed-layer depths during MHWs.This study highlights that combining the deep learning technique with a dynamical model can improve MHW forecasting and has certain physical interpretability.展开更多
Siberian-Arctic heatwaves(SAHs)disrupt ecosystems by increasing wildfires,thawing permafrost,and threatening Arctic communities.As SAHs become more frequent and intense,accurate prediction is crucial for preparedness ...Siberian-Arctic heatwaves(SAHs)disrupt ecosystems by increasing wildfires,thawing permafrost,and threatening Arctic communities.As SAHs become more frequent and intense,accurate prediction is crucial for preparedness and mitigating their impacts.We demonstrate that April surface temperatures in the Siberian Arctic can be predicted one month in advance with a skill of 0.75(1979-2022)using a regression model based on Arctic stratospheric ozone,the Arctic Oscillation,and sea ice in the Kara Sea.This model successfully predicts six of seven SAHs,identifying three driven by extreme ozone depletion and three by significant sea-ice loss.Additionally,from 1979 to 1997,warming was primarily caused by ozone depletion,while from 1998 to 2022,sea-ice loss became the main factor.Our findings indicate that SAHs are predictable and recommend this model for real-time monitoring and forecasting,highlighting its potential to enhance preparedness and reduce adverse effects.展开更多
The frequency of marine heatwaves(MHWs)in the South China Sea(SCS)has increased recently.However,the relative roles of thermal and dynamic processes regulating the changes of sCs MHWs remain an open question.This stud...The frequency of marine heatwaves(MHWs)in the South China Sea(SCS)has increased recently.However,the relative roles of thermal and dynamic processes regulating the changes of sCs MHWs remain an open question.This study examines all long-lived MHWs(>10 days)in the SCS from 1982 to 2021,categorizing them into intensified and attenuated MHWs based on the overall trend of sea surface temperature during an MHW event.A mixed-layer heat budget analysis reveals that the thermal processes primarily driven by the latent heat flux are crucial in modulating the SCS MHWs,particularly for attenuated MHWs.However,under intensified conditions,the proportions of dynamically dominated MHWs(40%)is approximately comparable to that of thermally dominated ones(47%).This study highlights the significance of dynamic processes in shaping SCS MHWs and discusses the potential impacts induced by tropical cyclones on these MHWs.展开更多
Under global warming,understanding the impact of urbanization on the characteristics of different heatwaves is important for sustainable development.In this study,we investigated the changes of heatwaves characteristi...Under global warming,understanding the impact of urbanization on the characteristics of different heatwaves is important for sustainable development.In this study,we investigated the changes of heatwaves characteristics in the Yangtze River Delta urban agglomeration(YRDUG)and analyzed the influencing mechanisms of urbanization.Results showed that:(1)the duration,frequency,and intensity of NHWs(Nighttime Heatwaves)and CHWs(Daytime-nighttime compound Heatwaves)had shown a significant increase and the CHWs showed the greatest increasing trend.Furthermore,the NHWs exhibited higher durations,frequencies,and intensities compared to DHWs(Daytime Heatwaves);(2)Since 1990,the DHWs and CHWs were greater in urban areas than in rural areas,NHWs had been more pronounced in rural areas than in urban centers;and(3)Cloud cover,solar radiation,etc.affected heatwaves.Furthermore,in the process of urbanization,the increase in impervious area and the decrease in green land exacerbated heatwaves.Considering the combined effect of DHWs and NHWs,CHWs continued to increase.展开更多
The thermal state of seawater is a fundamental property of the ocean.Extreme changes in the ocean's thermal conditions can significantly impact the marine environment,climate system,ecosystems,and economic activit...The thermal state of seawater is a fundamental property of the ocean.Extreme changes in the ocean's thermal conditions can significantly impact the marine environment,climate system,ecosystems,and economic activities.Marine heatwaves(MHWs)are extreme high-temperature events occurring in the ocean at weather or short-to-medium-term climate scales,representing extreme variations in oceanic conditions(Pearce et al.,2011;Feng et al.,2013;Hobday et al.,2016).展开更多
Marine heatwaves(MHWs),which can exert devastating socioeconomic and ecological impacts,have attracted much public interest in recent years.In this study,we evaluate the sub-seasonal forecast skill of MHWs based on th...Marine heatwaves(MHWs),which can exert devastating socioeconomic and ecological impacts,have attracted much public interest in recent years.In this study,we evaluate the sub-seasonal forecast skill of MHWs based on the Nanjing University of Information Science&Technology Climate Forecast System version 1.1(NUIST CFS1.1)and analyze the related physical processes.Our results show that the model can accurately forecast the occurrence of MHWs on a global scale out to a lead time of 25 days.Notably,even at lead times of 51–55 days,the forecast skill in most tropical regions,as well as in the northeastern and southeastern Pacific,is superior to both random forecasts and persistence forecasts.Accurate predictions of sea level pressure,zonal currents,and mixed-layer depth are important for MHW forecasting.Furthermore,we also conduct forecast skill assessments for two well-documented MHW events.Due to its ability to correctly forecast the changes in heat flux anomalies at a lead time of 25 days,the model can accurately forecast the strong MHW event that occurred in the South China Sea in May–October 2020.However,the forecasting results were less than optimal for the strong MHW event that occurred along the Australian west coast in January–April 2011.Although the model accurately forecasts its occurrence,the forecast of its intensity is poor.Additionally,when the lead time exceeds 10 days,forecasts of the relevant physical processes of this MHW event are also inaccurate.展开更多
A remarkable marine heatwave,known as the“Blob”,occurred in the Northeast Pacific Ocean from late 2013 to early 2016,which displayed strong warm anomalies extending from the surface to a depth of 300 m.This study em...A remarkable marine heatwave,known as the“Blob”,occurred in the Northeast Pacific Ocean from late 2013 to early 2016,which displayed strong warm anomalies extending from the surface to a depth of 300 m.This study employed two assimilation schemes based on the global Climate Forecast System of Nanjing University of Information Science(NUIST-CFS 1.0)to investigate the impact of ocean data assimilation on the seasonal prediction of this extreme marine heatwave.The sea surface temperature(SST)nudging scheme assimilates SST only,while the deterministic ensemble Kalman filter(EnKF)scheme assimilates observations from the surface to the deep ocean.The latter notably improves the forecasting skill for subsurface temperature anomalies,especially at the depth of 100-300 m(the lower layer),outperforming the SST nudging scheme.It excels in predicting both horizontal and vertical heat transport in the lower layer,contributing to improved forecasts of the lower-layer warming during the Blob.These improvements stem from the assimilation of subsurface observational data,which are important in predicting the upper-ocean conditions.The results suggest that assimilating ocean data with the EnKF scheme significantly enhances the accuracy in predicting subsurface temperature anomalies during the Blob and offers better understanding of its underlying mechanisms.展开更多
1 Today,many people face the challenge of extreme summer heat,often relying on air conditioning to stay cool.However,air conditioning consumes significant energy and contributes to climate change.To address this issue...1 Today,many people face the challenge of extreme summer heat,often relying on air conditioning to stay cool.However,air conditioning consumes significant energy and contributes to climate change.To address this issue,researchers are exploring innovative cooling methods inspired by both ancient techniques and modern technology.展开更多
Marine heatwaves(MHWs)are extreme ocean events characterized by anomalously warm upper-ocean temperatures,posing significant threats to marine ecosystems.While various factors driving MHWs have been extensively studie...Marine heatwaves(MHWs)are extreme ocean events characterized by anomalously warm upper-ocean temperatures,posing significant threats to marine ecosystems.While various factors driving MHWs have been extensively studied,the role of ocean salinity remains poorly understood.This study investigates the influence of salinity on the major 2013-2014 MHW event in the Northeast Pacific using reanalysis data and climate model outputs.Our results show that salinity variabilities are crucial for the development of the MHW event.Notably,a significant negative correlation exists between sea surface temperature anomalies(SSTAs)and sea surface salinity anomalies(SSSAs)during the MHW,with the SSSAs emerging simultaneously with SSTAs in the same area.Negative salinity anomalies(SAs)result in a shallower mixed layer,which suppresses vertical mixing and thus sustains the upper-ocean warming.Moreover,salinity has a greater impact on mixed layer depth anomalies than temperature.Model sensitivity experiments further demonstrate that negative SAs during MHWs amplify positive SSTAs by enhancing upper-ocean stratification,intensifying the MHW.Additionally,our analysis indicates that the SAs are predominantly driven by local freshwater flux anomalies,which are mainly induced by positive precipitation anomalies during the MHW event.展开更多
Sub-seasonal prediction of regional compound heatwaves and their predictability sources remain unclear.In this study,the underlying mechanisms for the long-lasting compound heatwave over Southern China during July 1–...Sub-seasonal prediction of regional compound heatwaves and their predictability sources remain unclear.In this study,the underlying mechanisms for the long-lasting compound heatwave over Southern China during July 1–18,2010,and the major sources of its sub-seasonal prediction skill are identified.The results show that both the development and decay of this compound heatwave are mainly dominated by atmospheric processes(i.e.,adiabatic heating associated with anticyclonic circulation),whereas land-atmosphere coupling processes play an important role in sustaining the heatwave.A further analysis indicates that by inducing anomalous anticyclonic circulations over Southern China,the tropical intraseasonal oscillations with periods of 30–60 days and 10–30 days facilitate the occurrence and maintenance of the heatwave during its entire and second half periods,respectively.The NCEP Climate Forecast System Version 2 shows a low skill in predicting the 2010 compound heatwave over Southern China when the lead time is longer than 2 pentads,which is largely attributed to the model’s bias in representing the intensity and phase of intra-seasonal oscillations.展开更多
Exposure assessment is critical for hazard risk management.It is important to investigate the cropland exposure to compound drought and heatwave(CDHW)events because of their severe impacts on agriculture.We quantified...Exposure assessment is critical for hazard risk management.It is important to investigate the cropland exposure to compound drought and heatwave(CDHW)events because of their severe impacts on agriculture.We quantified the variations in CDHW characteristics(i.e.,frequency,duration,and magnitude)and the cropland exposure to CDHW events in Northeast China using 20 CMIP6 climate projections for each of the four Shared Socioeconomic Pathways(i.e.,SSP126,SSP245,SSP370,and SSP585).The results indicate that the intensification of CDHW events leading to an anticipated increase in cropland exposure ranges from 1.6-fold to 5.8-fold(the range describes the differences among SSPs),with the west and northeast of the region poised to experience more pronounced increases.Notably,adherence to the SSP126 pathway can reduce both the increase rate of CDHW magnitude and cropland exposure compared to other SSPs.Path analysis demonstrates that cropland exposure is primarily driven by maximum temperature(Tmax).Although precipitation(Pre)increases(0.36-0.75 mm year^(-1)),the rise in potential evapotranspiration(PET)due to global warming is higher than that of Pre(0.26-1.07 mm year^(-1))except for SSP126,resulting in more drought events.Futhermore,elevated Tmax increases the frequency of extreme temperature events.Therefore,increases in Tmax and agricultural land area collectively contribute to exposure rise,with Tmax being the dominant factor in this process.Our findings emphasize the pivotal role of regulating the development pathway into SSP126 for sustainable agriculture,and optimizing crop patterns and planting heat-tolerant crop varieties are recommended for CDHW adaption.展开更多
Typhoon Hinnamnor(2022)was the only tropical cyclone(TC)during 1982-2023 that maintained strong or higher intensity north of 25°N while undergoing two rapid intensification(RI)events under marine heatwave(MHW)con...Typhoon Hinnamnor(2022)was the only tropical cyclone(TC)during 1982-2023 that maintained strong or higher intensity north of 25°N while undergoing two rapid intensification(RI)events under marine heatwave(MHW)conditions.These RI events differed significantly in both duration and intensification rates.This study investigated the role of MHWs in modulating these events,with a focus on variations in ocean stratification and atmospheric circulation.The results revealed that the first RI lasted 18 h,during which typhoon Hinnamnor intensified from a strong tropical storm to a super typhoon,which was driven primarily by oceanic thermal conditions.The anomalous MHW deepened the warm subsurface waters,leading to sustained accumulation of upper ocean heat content(UOHC),which fueled the RI.The cyclone’s rapid movement and moderate intensity helped preserve the abnormally thick barrier layer(BL),which maintained the UOHC via a subsurface“heat pump”effect,thus supporting continued intensification.In contrast,the second RI lasted only 6 h and involved a one-category intensification from a strong typhoon to a super typhoon,influenced by both oceanic and atmospheric factors.The prolonged and intensified MHW maintained a high UOHC,while strong upper-level divergence,increased mid-level moisture and low-level convergence enhanced deep convection,triggering the RI.However,a shallow mixed layer confined warm anomalies to the surface,whereas the cyclone’s slower movement,stronger winds,and thinner BL induced cold water upwelling.This“cold suction”effect depleted the UOHC,prematurely terminating the RI.These findings highlight the complex interplay between oceanic and atmospheric factors in shaping TC intensification under MHW conditions,emphasizing the critical role of upper ocean stratification in improving TC intensity forecasts.展开更多
Marine heatwave(MHW)events refer to periods of significantly elevated sea surface temperatures(SST),persisting from days to months,with significant impacts on marine ecosystems,including increased mortality among mari...Marine heatwave(MHW)events refer to periods of significantly elevated sea surface temperatures(SST),persisting from days to months,with significant impacts on marine ecosystems,including increased mortality among marine life and coral bleaching.Forecasting MHW events are crucial to mitigate their harmful effects.This study presents a twostep forecasting process:short-term SST prediction followed by MHW event detection based on the forecasted SST.Firstly,we developed the“SST-MHW-DL”model using the ConvLSTM architecture,which incorporates an attention mechanism to enhance both SST forecasting and MHW event detection.The model utilizes SST data from the preceding 60 d to forecast SST and detect MHW events for the subsequent 15 d.Verification results for SST forecasting demonstrate a root mean square error(RMSE)of 0.64℃,a mean absolute percentage error(MAPE)of 2.05%,and a coefficient of determination(R^(2))of 0.85,indicating the model’s ability to accurately predict future temperatures by leveraging historical sea temperature information.For MHW event detection using forecasted SST,the evaluation metrics of“accuracy”,“precision”,and“recall”achieved values of 0.77,0.73,and 0.43,respectively,demonstrating the model’s capability to capture the occurrence of MHW events accurately.Furthermore,the attention-enhanced mechanism reveals that recent SST variations within the past 10 days have the most significant impact on forecasting accuracy,while variations in deep-sea regions and along the Taiwan Strait significantly contribute to the model’s efficacy in capturing spatial characteristics.Additionally,the proposed model and temporal mechanism were applied to detect MHWs in the Atlantic Ocean.By inputting 30 d of SST data,the model predicted SST with an RMSE of 1.02℃and an R^(2)of 0.94.The accuracy,precision,and recall for MHW detection were 0.79,0.78,and 0.62,respectively,further demonstrating the model’s robustness and usability.展开更多
Using complex network methods,we construct undirected and directed heatwave networks to systematically analyze heatwave events over China from 1961 to 2023,exploring their spatiotemporal evolution patterns in differen...Using complex network methods,we construct undirected and directed heatwave networks to systematically analyze heatwave events over China from 1961 to 2023,exploring their spatiotemporal evolution patterns in different regions.The findings reveal a significant increase in heatwaves since the 2000s,with the average occurrence rising from approximately 3 to 5 times,and their duration increasing from 15 to around 30 days,nearly doubling.An increasing trend of“early onset and late withdrawal”of heatwaves has become more pronounced each year.In particular,eastern regions experience heatwaves that typically start earlier and tend to persist into September,exhibiting greater interannual variability compared to western areas.The middle and lower reaches of the Yangtze River and Xinjiang are identified as high-frequency heatwave areas.Complex network analysis reveals the dynamics of heatwave propagation,with degree centrality and synchronization distance indicating that the middle and lower reaches of the Yangtze River,Northeast China,and Xinjiang are key nodes in heatwave spread.Additionally,network divergence analysis shows that Xinjiang acts as a“source”area for heatwaves,exporting heat to surrounding regions,while the central region functions as a major“sink,”receiving more heatwave events.Further analysis from 1994 to 2023 indicates that heatwave events exhibit stronger network centrality and more complex synchronization patterns.These results suggest that complex networks provide a refined framework for depicting the spatiotemporal dynamics of heatwave propagation,offering new avenues for studying their occurrence and development patterns.展开更多
India is highly vulnerable to climate change and is going to increase its average annual temperature over the next few decades.The impact of heatwaves and related mortality is a concern for the country.In this paper,w...India is highly vulnerable to climate change and is going to increase its average annual temperature over the next few decades.The impact of heatwaves and related mortality is a concern for the country.In this paper,we aim to study the heatwaves and heat stress-related Heat Index vulnerability using heat index temperature.In this analysis,a heat in-dex temperature is calculated based on temperature and relative humidity for six different states(Delhi,West Bengal,Punjab,Uttar Pradesh,Andhra Pradesh,and Madhya Pradesh)of India to determine the heat stress vulnerability for which heat cramps and heat strokes are possible.Our analysis shows that most of the heatwaves and severe heatwaves occurred during 2010 for all the states.The heatwaves are observed only in the summer months.All the states of our study reached the Extreme Caution category of the Heat Index showing the Danger to Extreme Danger category dur-ing April to June.Future projection scenarios show an increase in heat stress-related vulnerability.SSP2-4.5 scenario showed that Delhi,Punjab,and West Bengal reached an Extreme Danger state during June for which death due to heat strokes is possible under continued exposure to heatwaves.The HI related vulnerability of SSP5-8.5 is like SSP2-4.5 except for Andhra Pradesh which shows an Extreme Danger state in May and June during which heat strokes are possi-ble under continued exposure to heatwaves.This study provides spatial variability of heat stress and Heat Index vulner-ability which may help adopt future strategies for heat-related policy implication.展开更多
Heatwaves are becoming increasingly frequent and severe,posing escalating risks to ecosystems and human well-being.While soil moisture(SM)deficits are recognized as important contributors to heatwave amplification,the...Heatwaves are becoming increasingly frequent and severe,posing escalating risks to ecosystems and human well-being.While soil moisture(SM)deficits are recognized as important contributors to heatwave amplification,their spatially heterogeneous impacts across the Northern Hemisphere remain insufficiently understood.In this study,we analyze ERA5 reanalysis data(1980-2022)to investigate trends in heatwave frequency,intensity,and duration,as well as their sensitivity to SM variability.Our results show robust increases in heatwave occurrence(0.76 events per decade),intensity(0.81℃per decade),and average duration(0.40 days per decade),with extreme events,as represented by maximum intensity and duration,rising at even faster rates(2.18℃per decade and 0.83 days per decade,respectively).Strong negative correlations are observed between SM deficits and heatwave metrics,with the magnitude of this relationship varying across land cover types and heatwave severity levels.Quantile regression reveals that SM reductions have a greater impact at higher quantiles for most indicators.Cropland exhibits the highest sensitivity to SM anomalies,whereas forests show more resilience due to their superior water retention capacities.These findings underscore the crucial role of land-atmosphere interactions in shaping heatwave extremes,providing a scientific basis for enhancing early warning and adaptation strategies in the context of ongoing climate change.展开更多
Marine heatwaves(MHWs)have become increasingly frequent and persistent in the context of global warming and the related underlying mechanisms are strongly region-dependent.We employed the NOAA(National Oceanic and Atm...Marine heatwaves(MHWs)have become increasingly frequent and persistent in the context of global warming and the related underlying mechanisms are strongly region-dependent.We employed the NOAA(National Oceanic and Atmospheric Administration)CRW(Coral Reef Watch)daily mean sea surface temperature dataset spanning from 1985 to 2022 to comprehensively analyze the fundamental attributes and evolving patterns of marine heatwaves in the offshore waters of China.Eight pronounced marine heatwaves from frequently affected sensitive regions were investigated to explore their formation mechanisms.The relationship between the occurrences of marine heatwave and large-scale climate mode in the region was explored.Results show that the western Pacific subtropical high plays an essential role in triggering marine heatwaves in Chinese offshore waters,with an anomalous downward shortwave radiation flux acting to warm the sea surface,which is remotely associated to the large-scale sea surface temperature state.Distinct mechanisms for the MHWs were identified in the northern and southern offshore waters of China.MHWs in high latitudes(such as the Bohai Sea and the Yellow Sea)mainly occur during the negative phase of the Pacific Decadal Oscillation(PDO),while those in low latitudes(such as the South China Sea)are more common in about 5-month lags behind the El Niño,for which we purposed a mechanism to describe the main differences in the formation of MHWs in China and discussed the related implications.展开更多
Bottom marine heatwaves(BMHWs),i.e.,anomalous ocean warming at the seafloor,can happen without concurrent surface marine heatwaves(SMHWs),which pose a serious threat to marine ecosystems and present a challenge to det...Bottom marine heatwaves(BMHWs),i.e.,anomalous ocean warming at the seafloor,can happen without concurrent surface marine heatwaves(SMHWs),which pose a serious threat to marine ecosystems and present a challenge to detect and study them adequately.This type of event is called independent BMHWs.This study examines the summertime BMHWs on the continental shelf of the East China Sea(ECS)using oceanic reanalysis data from 1993 to 2020.Our results show that summertime BMHWs in the ECS are generally more intense than SMHWs,with some BMHW events occurring without surface expression.Through heat budget analyses of the 2016 SMHW event and the 2019 BMHW event,we investigated the drivers of independent summertime BMHWs.It is indicated that the occurrences of bottom temperature anomalies in summer are predominantly attributed to oceanic horizontal advection.Specifically,the summertime BMHWs on the central ECS shelf are closely related to the strengthening of the inshore branch of the Taiwan Warm Current(TWC)and the weakening of the offshore TWC branch.These findings provide important insights into the underlying physical processes and diagnostic tools for monitoring and managing independent BMHWs in the ECS.展开更多
Marine heatwaves(MHWs)in the East China Sea(ECS),especially those occurring on the ocean bottom(referred to as bottom marine heatwaves,BMHWs),can significantly affect regional ecosystems.However,our understanding of t...Marine heatwaves(MHWs)in the East China Sea(ECS),especially those occurring on the ocean bottom(referred to as bottom marine heatwaves,BMHWs),can significantly affect regional ecosystems.However,our understanding of the seasonal variations in the MHWs in the ECS remains limited.This study investigates the characteristics of MHWs in the ECS in summer and winter using high-resolution oceanic reanalysis.Our analyses reveal distinct spatial patterns of BMHWs in these seasons.During summer,the Taiwan Warm Current plays a crucial role in transporting warm water northward,potentially leading to intense BMHWs on the central ECS shelf.These BMHW events usually occur independently of surface warming due to strong stratification in summer.Conversely,winter BMHWs are more prevalent in coastal regions under the influence of coastal currents and typically feature consistent warming from surface to bottom with a deepened mixed layer.These findings inform the coherent vertical structure and driving mechanisms of MHWs in the ECS,which are essential for predicting and managing these extreme events in the future.展开更多
基金supported by the British Columbia Ministry of Forces through long-term annual contracts with University of British Columbia(Okanagan)(No.RE25SIR242)the Natural Sciences and Engineering Research Council of Canada(NSERC),Discovery Grants Program(No.RGPIN-2021-02628)+1 种基金supported by the China Postdoctoral Science Foundation(No.2024M760387)Heilongjiang Postdoctoral Financial Assistance(No.LBH-Z24062)。
文摘Extreme climate events(e.g.,heatwaves and droughts)are becoming increasingly frequent due to global climate change,which inevitably affects tree growth and various other ecological processes.While the impacts of droughts on these processes have been widely evaluated,the effects of heatwaves on tree growth and soil water content(SWC)remain poorly understood,particularly those related to thinning treatment.In this study,we evaluated the impacts of the 2021 Pacific Northwest Heatwave and thinning on forest growth and SWC,as well as assessed how thinning might mitigate the heatwave's impacts in lodgepole pine forests in British Columbia,Canada.We measured meteorological data(air temperature,rainfall,solar radiation(SR),relative humidity(RH),and wind speed(W_(s)),sap flow,SWC,soil temperature(T_(s)),and tree diameters at the breast height(DBH)during the growing season(June–September)in the control(27,000 stems·ha^(-1)),lightly thinned(4,500 stems·ha^(-1)),and heavily thinned(1,100 stems·ha^(-1))experimental plots from 2018 to 2024.We found that thinning persistently and significantly(p<0.05)increased individual tree growth,with the most pronounced effects in the heavily thinned stands.The 2021 Pacific Northwest Heatwave led to an exceptionally hot growing season,significantly(p<0.05)reducing forest growth and SWC across all plots.Forest growth recovered in 2022 in the thinned plots but remained suppressed in the unthinned plots,suggesting that thinning effectively mitigated the impact of the heatwave on forest growth,while the heatwave's impacts were persistent in the unthinned plots.Our study highlights that thinning is a practical management strategy for improving tree growth and supporting climate change adaptation to extreme climate events.
基金supported by the National Natural Science Foundation of China [grant numbers 42375168 and 42205035]a Shanghai Science and Technology Commission Project [grant number 23DZ1204704]。
文摘Marine heatwaves(MHWs)in the South China Sea(SCS)significantly impact marine ecosystems and socioeconomic development,yet accurately forecasting MHWs remains a challenge.This study developed an upper-ocean temperature forecasting model based on ConvLSTM for the northern SCS and,in conjunction with the ocean forecasting system LICOM Forecast System(LFS),constructed a hybrid Fusion model using Wasserstein-Distance optimization.The ability of these three models to forecast key MHW metrics with a 10-day lead was assessed during the summer of 2022 in the SCS.Overall,the Fusion model takes advantage of LFS and ConvLSTM,providing superior forecasts for both the duration and intensity of MHWs in the southern SCS.LFS(ConvLSTM)overestimates(underestimates)the duration of MHWs and all models exhibit limitations in forecasting the intensity of MHWs in part of the SCS.The Fusion model's superior forecast skill for MHWs may be attributable to its more realistic representation of the upper-ocean thermal structure with shallower mixed-layer depths during MHWs.This study highlights that combining the deep learning technique with a dynamical model can improve MHW forecasting and has certain physical interpretability.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFF0805104)the National Natural Science Foundation of China(NSFC)under Grant Nos.41925022,42105016 and 42375070+1 种基金supported by the NSFC under Grant No.41888101the Natural Sciences and Engineering Research Council of Canada(Grant No.RGPIN-2019-04511)。
文摘Siberian-Arctic heatwaves(SAHs)disrupt ecosystems by increasing wildfires,thawing permafrost,and threatening Arctic communities.As SAHs become more frequent and intense,accurate prediction is crucial for preparedness and mitigating their impacts.We demonstrate that April surface temperatures in the Siberian Arctic can be predicted one month in advance with a skill of 0.75(1979-2022)using a regression model based on Arctic stratospheric ozone,the Arctic Oscillation,and sea ice in the Kara Sea.This model successfully predicts six of seven SAHs,identifying three driven by extreme ozone depletion and three by significant sea-ice loss.Additionally,from 1979 to 1997,warming was primarily caused by ozone depletion,while from 1998 to 2022,sea-ice loss became the main factor.Our findings indicate that SAHs are predictable and recommend this model for real-time monitoring and forecasting,highlighting its potential to enhance preparedness and reduce adverse effects.
基金supported by the National Key R&D Program of China[grant number 2022YFF0801400]the National Natural Science Foundation of China [grant numbers 42376027 and W2441014]+2 种基金the Development Fund of the South China Sea Institute of Oceanology of the Chinese Academy of Sciences [grant number SCSIO202208]the Special Fund of the South China Sea Institute of Oceanology of the Chinese Academy of Sciences [grant number SCSIO2023QY01]the Science and Technology Projects in Guangzhou [grant number 202201010367]。
文摘The frequency of marine heatwaves(MHWs)in the South China Sea(SCS)has increased recently.However,the relative roles of thermal and dynamic processes regulating the changes of sCs MHWs remain an open question.This study examines all long-lived MHWs(>10 days)in the SCS from 1982 to 2021,categorizing them into intensified and attenuated MHWs based on the overall trend of sea surface temperature during an MHW event.A mixed-layer heat budget analysis reveals that the thermal processes primarily driven by the latent heat flux are crucial in modulating the SCS MHWs,particularly for attenuated MHWs.However,under intensified conditions,the proportions of dynamically dominated MHWs(40%)is approximately comparable to that of thermally dominated ones(47%).This study highlights the significance of dynamic processes in shaping SCS MHWs and discusses the potential impacts induced by tropical cyclones on these MHWs.
基金National Natural Science Foundation of China,No.42271037Natural Science Foundation of Anhui Province,No.2408085MD095+2 种基金Key Research and Development Program Project of Anhui Province,No.2022m07020011University Synergy Innovation Program of Anhui Province,No.GXXT-2021-048Science Foundation for Excellent Young Scholars of Anhui,No.2108085Y13。
文摘Under global warming,understanding the impact of urbanization on the characteristics of different heatwaves is important for sustainable development.In this study,we investigated the changes of heatwaves characteristics in the Yangtze River Delta urban agglomeration(YRDUG)and analyzed the influencing mechanisms of urbanization.Results showed that:(1)the duration,frequency,and intensity of NHWs(Nighttime Heatwaves)and CHWs(Daytime-nighttime compound Heatwaves)had shown a significant increase and the CHWs showed the greatest increasing trend.Furthermore,the NHWs exhibited higher durations,frequencies,and intensities compared to DHWs(Daytime Heatwaves);(2)Since 1990,the DHWs and CHWs were greater in urban areas than in rural areas,NHWs had been more pronounced in rural areas than in urban centers;and(3)Cloud cover,solar radiation,etc.affected heatwaves.Furthermore,in the process of urbanization,the increase in impervious area and the decrease in green land exacerbated heatwaves.Considering the combined effect of DHWs and NHWs,CHWs continued to increase.
基金Supported by the National Natural Science Foundation of China(No.42476016)the Laoshan Laboratory(No.LSKJ202202702)the Indo-Pacific Ocean and Climate Laboratory Project(No.424530)from Hohai University。
文摘The thermal state of seawater is a fundamental property of the ocean.Extreme changes in the ocean's thermal conditions can significantly impact the marine environment,climate system,ecosystems,and economic activities.Marine heatwaves(MHWs)are extreme high-temperature events occurring in the ocean at weather or short-to-medium-term climate scales,representing extreme variations in oceanic conditions(Pearce et al.,2011;Feng et al.,2013;Hobday et al.,2016).
基金supported by National Natural Science Foundation of China(Grant Nos.42030605 and 42088101)National Key R&D Program of China(Grant No.2020YFA0608004)High Performance Computing of Nanjing University of Information Science&Technology for their support of this work。
文摘Marine heatwaves(MHWs),which can exert devastating socioeconomic and ecological impacts,have attracted much public interest in recent years.In this study,we evaluate the sub-seasonal forecast skill of MHWs based on the Nanjing University of Information Science&Technology Climate Forecast System version 1.1(NUIST CFS1.1)and analyze the related physical processes.Our results show that the model can accurately forecast the occurrence of MHWs on a global scale out to a lead time of 25 days.Notably,even at lead times of 51–55 days,the forecast skill in most tropical regions,as well as in the northeastern and southeastern Pacific,is superior to both random forecasts and persistence forecasts.Accurate predictions of sea level pressure,zonal currents,and mixed-layer depth are important for MHW forecasting.Furthermore,we also conduct forecast skill assessments for two well-documented MHW events.Due to its ability to correctly forecast the changes in heat flux anomalies at a lead time of 25 days,the model can accurately forecast the strong MHW event that occurred in the South China Sea in May–October 2020.However,the forecasting results were less than optimal for the strong MHW event that occurred along the Australian west coast in January–April 2011.Although the model accurately forecasts its occurrence,the forecast of its intensity is poor.Additionally,when the lead time exceeds 10 days,forecasts of the relevant physical processes of this MHW event are also inaccurate.
基金supported by the National Natural Science Foundation of China [grant number 42030605]the National Key R&D Program of China [grant number 2020YFA0608004]。
文摘A remarkable marine heatwave,known as the“Blob”,occurred in the Northeast Pacific Ocean from late 2013 to early 2016,which displayed strong warm anomalies extending from the surface to a depth of 300 m.This study employed two assimilation schemes based on the global Climate Forecast System of Nanjing University of Information Science(NUIST-CFS 1.0)to investigate the impact of ocean data assimilation on the seasonal prediction of this extreme marine heatwave.The sea surface temperature(SST)nudging scheme assimilates SST only,while the deterministic ensemble Kalman filter(EnKF)scheme assimilates observations from the surface to the deep ocean.The latter notably improves the forecasting skill for subsurface temperature anomalies,especially at the depth of 100-300 m(the lower layer),outperforming the SST nudging scheme.It excels in predicting both horizontal and vertical heat transport in the lower layer,contributing to improved forecasts of the lower-layer warming during the Blob.These improvements stem from the assimilation of subsurface observational data,which are important in predicting the upper-ocean conditions.The results suggest that assimilating ocean data with the EnKF scheme significantly enhances the accuracy in predicting subsurface temperature anomalies during the Blob and offers better understanding of its underlying mechanisms.
文摘1 Today,many people face the challenge of extreme summer heat,often relying on air conditioning to stay cool.However,air conditioning consumes significant energy and contributes to climate change.To address this issue,researchers are exploring innovative cooling methods inspired by both ancient techniques and modern technology.
基金The Laoshan Laboratory under contract Nos LSKJ202202403 and LSKJ202202402the National Natural Science Foundation of China under contract Nos 42030410 and 42406202+3 种基金the Natural Science Foundation of Jiangsu Province under contract No.BK20240718the Startup Foundation for Introducing Talent of Nanjing University of Information Science and Technologythe Jiangsu Innovation Research Group under contract No.JSSCTD202346the Jiangsu Funding Program for Excellent Postdoctoral Talent under contract No.2023ZB690.
文摘Marine heatwaves(MHWs)are extreme ocean events characterized by anomalously warm upper-ocean temperatures,posing significant threats to marine ecosystems.While various factors driving MHWs have been extensively studied,the role of ocean salinity remains poorly understood.This study investigates the influence of salinity on the major 2013-2014 MHW event in the Northeast Pacific using reanalysis data and climate model outputs.Our results show that salinity variabilities are crucial for the development of the MHW event.Notably,a significant negative correlation exists between sea surface temperature anomalies(SSTAs)and sea surface salinity anomalies(SSSAs)during the MHW,with the SSSAs emerging simultaneously with SSTAs in the same area.Negative salinity anomalies(SAs)result in a shallower mixed layer,which suppresses vertical mixing and thus sustains the upper-ocean warming.Moreover,salinity has a greater impact on mixed layer depth anomalies than temperature.Model sensitivity experiments further demonstrate that negative SAs during MHWs amplify positive SSTAs by enhancing upper-ocean stratification,intensifying the MHW.Additionally,our analysis indicates that the SAs are predominantly driven by local freshwater flux anomalies,which are mainly induced by positive precipitation anomalies during the MHW event.
基金Guangdong Major Project of Basic and Applied Basic Research(2020B0301030004)National Natural Science Foundation of China(42105015)+3 种基金Guangdong Basic and Applied Basic Research Foundation(2022A1515010659)Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(SML2023SP209)Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(311021001)Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies(2020B1212060025)。
文摘Sub-seasonal prediction of regional compound heatwaves and their predictability sources remain unclear.In this study,the underlying mechanisms for the long-lasting compound heatwave over Southern China during July 1–18,2010,and the major sources of its sub-seasonal prediction skill are identified.The results show that both the development and decay of this compound heatwave are mainly dominated by atmospheric processes(i.e.,adiabatic heating associated with anticyclonic circulation),whereas land-atmosphere coupling processes play an important role in sustaining the heatwave.A further analysis indicates that by inducing anomalous anticyclonic circulations over Southern China,the tropical intraseasonal oscillations with periods of 30–60 days and 10–30 days facilitate the occurrence and maintenance of the heatwave during its entire and second half periods,respectively.The NCEP Climate Forecast System Version 2 shows a low skill in predicting the 2010 compound heatwave over Southern China when the lead time is longer than 2 pentads,which is largely attributed to the model’s bias in representing the intensity and phase of intra-seasonal oscillations.
基金financially supported by the National Key Research and Development Program of China(Grant No.2023YFF0805704)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA28020503)。
文摘Exposure assessment is critical for hazard risk management.It is important to investigate the cropland exposure to compound drought and heatwave(CDHW)events because of their severe impacts on agriculture.We quantified the variations in CDHW characteristics(i.e.,frequency,duration,and magnitude)and the cropland exposure to CDHW events in Northeast China using 20 CMIP6 climate projections for each of the four Shared Socioeconomic Pathways(i.e.,SSP126,SSP245,SSP370,and SSP585).The results indicate that the intensification of CDHW events leading to an anticipated increase in cropland exposure ranges from 1.6-fold to 5.8-fold(the range describes the differences among SSPs),with the west and northeast of the region poised to experience more pronounced increases.Notably,adherence to the SSP126 pathway can reduce both the increase rate of CDHW magnitude and cropland exposure compared to other SSPs.Path analysis demonstrates that cropland exposure is primarily driven by maximum temperature(Tmax).Although precipitation(Pre)increases(0.36-0.75 mm year^(-1)),the rise in potential evapotranspiration(PET)due to global warming is higher than that of Pre(0.26-1.07 mm year^(-1))except for SSP126,resulting in more drought events.Futhermore,elevated Tmax increases the frequency of extreme temperature events.Therefore,increases in Tmax and agricultural land area collectively contribute to exposure rise,with Tmax being the dominant factor in this process.Our findings emphasize the pivotal role of regulating the development pathway into SSP126 for sustainable agriculture,and optimizing crop patterns and planting heat-tolerant crop varieties are recommended for CDHW adaption.
基金The National Natural Science Foundation of China under contract Nos 42275024,42405063,42575023,W2441014,and 42176001the Guangdong Basic and Applied Basic Research Foundation under contract Nos 2023B1515020009 and 2024B1515040024+1 种基金the Special Fund of the South China Sea Institute of Oceanology,Chinese Academy of Sciences,under contract Nos SCSIO2023QY01 and SCSIO2023HC07the Science and Technology Planning Project of Guangzhou under contract No.2024A04J6275.
文摘Typhoon Hinnamnor(2022)was the only tropical cyclone(TC)during 1982-2023 that maintained strong or higher intensity north of 25°N while undergoing two rapid intensification(RI)events under marine heatwave(MHW)conditions.These RI events differed significantly in both duration and intensification rates.This study investigated the role of MHWs in modulating these events,with a focus on variations in ocean stratification and atmospheric circulation.The results revealed that the first RI lasted 18 h,during which typhoon Hinnamnor intensified from a strong tropical storm to a super typhoon,which was driven primarily by oceanic thermal conditions.The anomalous MHW deepened the warm subsurface waters,leading to sustained accumulation of upper ocean heat content(UOHC),which fueled the RI.The cyclone’s rapid movement and moderate intensity helped preserve the abnormally thick barrier layer(BL),which maintained the UOHC via a subsurface“heat pump”effect,thus supporting continued intensification.In contrast,the second RI lasted only 6 h and involved a one-category intensification from a strong typhoon to a super typhoon,influenced by both oceanic and atmospheric factors.The prolonged and intensified MHW maintained a high UOHC,while strong upper-level divergence,increased mid-level moisture and low-level convergence enhanced deep convection,triggering the RI.However,a shallow mixed layer confined warm anomalies to the surface,whereas the cyclone’s slower movement,stronger winds,and thinner BL induced cold water upwelling.This“cold suction”effect depleted the UOHC,prematurely terminating the RI.These findings highlight the complex interplay between oceanic and atmospheric factors in shaping TC intensification under MHW conditions,emphasizing the critical role of upper ocean stratification in improving TC intensity forecasts.
基金The National Natural Science Foundation of China under contract Nos 42376175,42090044 and U2006211。
文摘Marine heatwave(MHW)events refer to periods of significantly elevated sea surface temperatures(SST),persisting from days to months,with significant impacts on marine ecosystems,including increased mortality among marine life and coral bleaching.Forecasting MHW events are crucial to mitigate their harmful effects.This study presents a twostep forecasting process:short-term SST prediction followed by MHW event detection based on the forecasted SST.Firstly,we developed the“SST-MHW-DL”model using the ConvLSTM architecture,which incorporates an attention mechanism to enhance both SST forecasting and MHW event detection.The model utilizes SST data from the preceding 60 d to forecast SST and detect MHW events for the subsequent 15 d.Verification results for SST forecasting demonstrate a root mean square error(RMSE)of 0.64℃,a mean absolute percentage error(MAPE)of 2.05%,and a coefficient of determination(R^(2))of 0.85,indicating the model’s ability to accurately predict future temperatures by leveraging historical sea temperature information.For MHW event detection using forecasted SST,the evaluation metrics of“accuracy”,“precision”,and“recall”achieved values of 0.77,0.73,and 0.43,respectively,demonstrating the model’s capability to capture the occurrence of MHW events accurately.Furthermore,the attention-enhanced mechanism reveals that recent SST variations within the past 10 days have the most significant impact on forecasting accuracy,while variations in deep-sea regions and along the Taiwan Strait significantly contribute to the model’s efficacy in capturing spatial characteristics.Additionally,the proposed model and temporal mechanism were applied to detect MHWs in the Atlantic Ocean.By inputting 30 d of SST data,the model predicted SST with an RMSE of 1.02℃and an R^(2)of 0.94.The accuracy,precision,and recall for MHW detection were 0.79,0.78,and 0.62,respectively,further demonstrating the model’s robustness and usability.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2022YFE0136000 and 2024YFC3013100)the Joint Meteorological Fund(Grant No.U2342211)+1 种基金the Joint Research Project for Meteorological Capacity Improvement(Grant No.22NLTSZ004)the National Meteorological Information Center(Grant No.NMICJY202301)。
文摘Using complex network methods,we construct undirected and directed heatwave networks to systematically analyze heatwave events over China from 1961 to 2023,exploring their spatiotemporal evolution patterns in different regions.The findings reveal a significant increase in heatwaves since the 2000s,with the average occurrence rising from approximately 3 to 5 times,and their duration increasing from 15 to around 30 days,nearly doubling.An increasing trend of“early onset and late withdrawal”of heatwaves has become more pronounced each year.In particular,eastern regions experience heatwaves that typically start earlier and tend to persist into September,exhibiting greater interannual variability compared to western areas.The middle and lower reaches of the Yangtze River and Xinjiang are identified as high-frequency heatwave areas.Complex network analysis reveals the dynamics of heatwave propagation,with degree centrality and synchronization distance indicating that the middle and lower reaches of the Yangtze River,Northeast China,and Xinjiang are key nodes in heatwave spread.Additionally,network divergence analysis shows that Xinjiang acts as a“source”area for heatwaves,exporting heat to surrounding regions,while the central region functions as a major“sink,”receiving more heatwave events.Further analysis from 1994 to 2023 indicates that heatwave events exhibit stronger network centrality and more complex synchronization patterns.These results suggest that complex networks provide a refined framework for depicting the spatiotemporal dynamics of heatwave propagation,offering new avenues for studying their occurrence and development patterns.
文摘India is highly vulnerable to climate change and is going to increase its average annual temperature over the next few decades.The impact of heatwaves and related mortality is a concern for the country.In this paper,we aim to study the heatwaves and heat stress-related Heat Index vulnerability using heat index temperature.In this analysis,a heat in-dex temperature is calculated based on temperature and relative humidity for six different states(Delhi,West Bengal,Punjab,Uttar Pradesh,Andhra Pradesh,and Madhya Pradesh)of India to determine the heat stress vulnerability for which heat cramps and heat strokes are possible.Our analysis shows that most of the heatwaves and severe heatwaves occurred during 2010 for all the states.The heatwaves are observed only in the summer months.All the states of our study reached the Extreme Caution category of the Heat Index showing the Danger to Extreme Danger category dur-ing April to June.Future projection scenarios show an increase in heat stress-related vulnerability.SSP2-4.5 scenario showed that Delhi,Punjab,and West Bengal reached an Extreme Danger state during June for which death due to heat strokes is possible under continued exposure to heatwaves.The HI related vulnerability of SSP5-8.5 is like SSP2-4.5 except for Andhra Pradesh which shows an Extreme Danger state in May and June during which heat strokes are possi-ble under continued exposure to heatwaves.This study provides spatial variability of heat stress and Heat Index vulner-ability which may help adopt future strategies for heat-related policy implication.
基金National Key Research and Development Plan of China,No.2023YFF0805703National Natural Science Foundation of China,No.42271268。
文摘Heatwaves are becoming increasingly frequent and severe,posing escalating risks to ecosystems and human well-being.While soil moisture(SM)deficits are recognized as important contributors to heatwave amplification,their spatially heterogeneous impacts across the Northern Hemisphere remain insufficiently understood.In this study,we analyze ERA5 reanalysis data(1980-2022)to investigate trends in heatwave frequency,intensity,and duration,as well as their sensitivity to SM variability.Our results show robust increases in heatwave occurrence(0.76 events per decade),intensity(0.81℃per decade),and average duration(0.40 days per decade),with extreme events,as represented by maximum intensity and duration,rising at even faster rates(2.18℃per decade and 0.83 days per decade,respectively).Strong negative correlations are observed between SM deficits and heatwave metrics,with the magnitude of this relationship varying across land cover types and heatwave severity levels.Quantile regression reveals that SM reductions have a greater impact at higher quantiles for most indicators.Cropland exhibits the highest sensitivity to SM anomalies,whereas forests show more resilience due to their superior water retention capacities.These findings underscore the crucial role of land-atmosphere interactions in shaping heatwave extremes,providing a scientific basis for enhancing early warning and adaptation strategies in the context of ongoing climate change.
基金Supported by the National Natural Science Foundation of China(No.41905089)the Laoshan Laboratory(No.LSKJ202202404)+1 种基金the Startup Foundation for Introducing Talent of NUIST,Jiangsu Innovation Research Group(No.JSSCTD202346)the Undergraduates Innovation and Entrepreneurship Training Program of Jiangsu Province(No.202310300087Y)。
文摘Marine heatwaves(MHWs)have become increasingly frequent and persistent in the context of global warming and the related underlying mechanisms are strongly region-dependent.We employed the NOAA(National Oceanic and Atmospheric Administration)CRW(Coral Reef Watch)daily mean sea surface temperature dataset spanning from 1985 to 2022 to comprehensively analyze the fundamental attributes and evolving patterns of marine heatwaves in the offshore waters of China.Eight pronounced marine heatwaves from frequently affected sensitive regions were investigated to explore their formation mechanisms.The relationship between the occurrences of marine heatwave and large-scale climate mode in the region was explored.Results show that the western Pacific subtropical high plays an essential role in triggering marine heatwaves in Chinese offshore waters,with an anomalous downward shortwave radiation flux acting to warm the sea surface,which is remotely associated to the large-scale sea surface temperature state.Distinct mechanisms for the MHWs were identified in the northern and southern offshore waters of China.MHWs in high latitudes(such as the Bohai Sea and the Yellow Sea)mainly occur during the negative phase of the Pacific Decadal Oscillation(PDO),while those in low latitudes(such as the South China Sea)are more common in about 5-month lags behind the El Niño,for which we purposed a mechanism to describe the main differences in the formation of MHWs in China and discussed the related implications.
基金Supported by the National Natural Science Foundation of China(No.42030410)the Laoshan Laboratory(Nos.LSKJ202202404,LSKJ202202403)+1 种基金the Startup Foundation for Introducing Talent of Nanjing University of Information Science and Technology(NUIST),Jiangsu Innovation Research Group(No.JSSCTD202346)the Jiangsu Funding Program for Excellent Postdoctoral Talent(No.2023ZB690)。
文摘Bottom marine heatwaves(BMHWs),i.e.,anomalous ocean warming at the seafloor,can happen without concurrent surface marine heatwaves(SMHWs),which pose a serious threat to marine ecosystems and present a challenge to detect and study them adequately.This type of event is called independent BMHWs.This study examines the summertime BMHWs on the continental shelf of the East China Sea(ECS)using oceanic reanalysis data from 1993 to 2020.Our results show that summertime BMHWs in the ECS are generally more intense than SMHWs,with some BMHW events occurring without surface expression.Through heat budget analyses of the 2016 SMHW event and the 2019 BMHW event,we investigated the drivers of independent summertime BMHWs.It is indicated that the occurrences of bottom temperature anomalies in summer are predominantly attributed to oceanic horizontal advection.Specifically,the summertime BMHWs on the central ECS shelf are closely related to the strengthening of the inshore branch of the Taiwan Warm Current(TWC)and the weakening of the offshore TWC branch.These findings provide important insights into the underlying physical processes and diagnostic tools for monitoring and managing independent BMHWs in the ECS.
基金The National Natural Science Foundation of China under contract No.42030410the Laoshan Laboratory under contract Nos LSKJ202202404 and LSKJ202202403+2 种基金the Startup Foundation for Introducing Talent of Nanjing University of Information Science and TechnologyJiangsu Innovation Research Group under contract No.JSSCTD202346Jiangsu Funding Program for Excellent Postdoctoral Talent under contract No.2023ZB690。
文摘Marine heatwaves(MHWs)in the East China Sea(ECS),especially those occurring on the ocean bottom(referred to as bottom marine heatwaves,BMHWs),can significantly affect regional ecosystems.However,our understanding of the seasonal variations in the MHWs in the ECS remains limited.This study investigates the characteristics of MHWs in the ECS in summer and winter using high-resolution oceanic reanalysis.Our analyses reveal distinct spatial patterns of BMHWs in these seasons.During summer,the Taiwan Warm Current plays a crucial role in transporting warm water northward,potentially leading to intense BMHWs on the central ECS shelf.These BMHW events usually occur independently of surface warming due to strong stratification in summer.Conversely,winter BMHWs are more prevalent in coastal regions under the influence of coastal currents and typically feature consistent warming from surface to bottom with a deepened mixed layer.These findings inform the coherent vertical structure and driving mechanisms of MHWs in the ECS,which are essential for predicting and managing these extreme events in the future.
