Based on reanalysis data from 1979 to 2021,this study explores the spatial distribution of the Southern Indian Ocean Dipole(SIOD)and its individual and synergistic effects with the El Niño-Southern Oscillation(EN...Based on reanalysis data from 1979 to 2021,this study explores the spatial distribution of the Southern Indian Ocean Dipole(SIOD)and its individual and synergistic effects with the El Niño-Southern Oscillation(ENSO)on summer precipitation in China.The inverse phase spatial distribution of sea surface temperature anomalies(SSTAs)in the southwest and northeast of the southern Indian Ocean is defined as the SIOD.Positive SIOD events(positive SSTAs in the southwest,negative SSTAs in the northeast)are associated with La Niña events(Central Pacific(CP)type),while negative SIOD events(negative SSTAs in the southwest,positive SSTAs in the northeast)are associated with El Niño events(Eastern Pacific(EP)type).Both SIOD and ENSO have certain impacts on summer precipitation in China.Precipitation in the Yangtze River basin decreases,while precipitation in southern China increases during pure positive SIOD(P_PSIOD)events.During pure negative SIOD(P_NSIOD)events,the changes in precipitation are exactly the opposite of those during P_PSIOD events,which may be due to differences in the cross-equatorial flow in the southern Indian Ocean,particularly in low-level Australian cross-equatorial flow.When positive SIOD and CP-type La Niña events occur simultaneously(PSIOD+La_Niña),precipitation increases in the Yangtze-Huaihe River basin,while it decreases in northern China.When negative SIOD and EP-type El Niño events occur simultaneously(NSIOD+El_Niño),precipitation in the Yangtze-Huaihe River basin is significantly lower than during P_NSIOD events.This is caused by differences in water vapor originating from the Pacific Ocean during different events.展开更多
Summer residential tourism is the future trend in China because of tourists’living quality improvement,heat crisis,rising market demand,and optimization of the destinations’residential environment,transport and acce...Summer residential tourism is the future trend in China because of tourists’living quality improvement,heat crisis,rising market demand,and optimization of the destinations’residential environment,transport and accessibility.Compared with summer tourism and vacation tourism,summer residential tourism had got less attention and lacks in prospective and preventive research.Hence,this study focused on potential assessment,pattern recognition and phase segmentation of 32 residential tourism destinations in China selected from 4 lists.An index system of 16 indicators from 5 dimensions was established as Summer Residence Index(SRI),and Range method,Entropy weight method and Composite index method were chosen as the core methods.Three main conclusions were as follows.(1)Only 2 typical districts’SRI value were near to 0.6,and 4 destinations were below 0.1,about 26 destinations were at medium-level,which indicated that China’s summer residential tourism was not so popular and only few destinations have stepped into a higher level.(2)Seven patterns could be recognized based on the contribution of the 5 dimensions to SRI value,including 3 single-factor driven patterns and 4 compound factors driven patterns.(3)Like tourist area life cycle(TALC),Unconscious stage,Initial stage,Developmental stage and Maturity stage could be segmented for summer residential destinations with the value of below 0.1,0.1-0.3,0.3-0.5,and above 0.5.Four destinations were under Unconscious stage.Twenty-two destinations were at initiate stage.Only 4 destinations have stepped into development stage and 2 at maturity stage.China’summer residential tourism has just started and has a better prospect.This study is just an attempt and needs further consideration,for example,a tracking study of SRI calculation for each year will be carried to justify the effectiveness of SRI and to check the rationality of the empirical results.As time goes on,policies in housing,residential estate and other aspects should be included as a factor in the SRI index.Data availability should be optimized because of better data sources and new technologies.Some other districts or cities in 2 batches of national Comprehensive Tourism Demonstration Zones(CTDZs)pilots and provincial CTDZs will be further selections of summer residential tourism destinations.展开更多
During the boreal summer,intraseasonal oscillations exhibit significant interannual variations in intensity over two key regions:the central-western equatorial Pacific(5°S-5°N,150°E-150°W)and the s...During the boreal summer,intraseasonal oscillations exhibit significant interannual variations in intensity over two key regions:the central-western equatorial Pacific(5°S-5°N,150°E-150°W)and the subtropical Northwestern Pacific(10°-20°N,130°E-175°W).The former is well-documented and considered to be influenced by the ENSO,while the latter has received comparatively less attention and is likely influenced by the Pacific Meridional Mode(PMM),as suggested by partial correlation analysis results.To elucidate the physical processes responsible for the enhanced(weakened)intraseasonal convection over the subtropical northwestern Pacific during warm(cold)PMM years,the authors employed a moisture budget analysis.The findings reveal that during warm PMM years,there is an increase in summer-mean moisture over the subtropical northwestern Pacific.This increase interacts with intensified vertical motion perturbations in the region,leading to greater vertical moisture advection in the lower troposphere and consequently resulting in convective instability.Such a process is pivotal in amplifying intraseasonal convection anomalies.The observational findings were further verified by model experiments forced by PMM-like sea surface temperature patterns.展开更多
Summer is my favorite season of the year.The weather is hot,but I don’t mind because there are so many fun things to do.In summer,I can swim in the pool with my friends.The cool water makes me feel really comfortable.
Soybeans are rich in protein,fats,vitamins,and minerals,serving as an important source of plant-based protein for humans.Summer soybean is widely cultivated in China,and improving its yield and quality is of great sig...Soybeans are rich in protein,fats,vitamins,and minerals,serving as an important source of plant-based protein for humans.Summer soybean is widely cultivated in China,and improving its yield and quality is of great significance for ensuring food security and promoting agricultural economic development.This paper elaborated on the high-quality and high-yield cultivation techniques for summer soybean,including variety selection,seed treatment,field selection and land preparation,sowing techniques,field management,pest and disease control,and harvesting,aiming to provide scientific cultivation guidance for summer soybean growers to achieve both superior quality and high yield.展开更多
Hello,everyone!I am Cici.I had a summer holiday that was both busy and happy.From July 11th to July 20th,I went to school every day to learn traditional Chinese painting.The soft brushes glided across the paper,creati...Hello,everyone!I am Cici.I had a summer holiday that was both busy and happy.From July 11th to July 20th,I went to school every day to learn traditional Chinese painting.The soft brushes glided across the paper,creating beautiful and vivid images.展开更多
Based on the C-Coupler platform,the semi-unstructured Climate System Model,Synthesis Community Integrated Model version 2(SYCIM2.0),has been developed at the School of Atmospheric Sciences,Sun Yat-sen University.SYCIM...Based on the C-Coupler platform,the semi-unstructured Climate System Model,Synthesis Community Integrated Model version 2(SYCIM2.0),has been developed at the School of Atmospheric Sciences,Sun Yat-sen University.SYCIM2.0 aims to meet the demand for seamless climate prediction through accurate climate simulations and projections.This paper provides an overview of SYCIM2.0 and highlights its key features,especially the coupling of an unstructured ocean model and the tuning process.An extensive evaluation of its performance,focusing on the East Asian Summer Monsoon(EASM),is presented based on long-term simulations with fixed external forcing.The results suggest that after nearly 240 years of integration,SYCIM2.0 achieves a quasi-equilibrium state,albeit with small trends in the net radiation flux at the top-of-atmosphere(TOA)and Earth’s surface,as well as with global mean near-surface temperatures.Compared to observational and reanalysis data,the model realistically simulates spatial patterns of sea surface temperature(SST)and precipitation centers to include their annual cycles,in addition to the lower-level wind fields in the EASM region.However,it exhibits a weakened and eastward-shifted Western Pacific Subtropical High(WPSH),resulting in an associated precipitation bias.SYCIM2.0 robustly captures the dominant mode of the EASM and its close relationship with the El Niño-Southern Oscillation(ENSO)but exhibits relatively poor performance in simulating the second leading mode and the associated air–sea interaction processes.Further comprehensive evaluations of SYCIM2.0 will be conducted in future studies.展开更多
This study conducts a comparative investigation between short-lived(3-8 days)and long-lived(9-24 days)break events of the South China Sea summer monsoon during 1979-2020,focusing on their statistical characteristics a...This study conducts a comparative investigation between short-lived(3-8 days)and long-lived(9-24 days)break events of the South China Sea summer monsoon during 1979-2020,focusing on their statistical characteristics and potential mechanisms for their different persistence.Results suggest that both types of events are characterized by anomalously suppressed convection accompanied by an anomalous anticyclone during the break period.However,these convection and circulation anomalies exhibit more localized patterns for short-lived events,but possess larger spatial scales and stronger intensities for long-lived events.The influence of tropical intraseasonal oscillations(ISOs)on short-and long-lived events is explored to interpret their different durations.It is found that for short-lived events,the 10-25-day oscillation is dominant in initiating and terminating the break,while the impact of the 30-60-day oscillation is secondary,thus resulting in a brief break period.In contrast,for long-lived events,the 10-25-day oscillation contributes to break development rather than its initiation,and concurrently,the 30-60-day oscillation shows a remarkable enhancement and plays a decisive role in prolonging the break duration.Furthermore,we find that long-lived events are preceded by significant ISO activities approximately two weeks before their occurrence,which can be regarded as efficient predictors.Associated with these precursory ISOs,the occurrence probability of break days for long-lived events can rise up to triple their original probability(35.43%vs.11.21%).展开更多
The intensified kernel position effect is a common phenomenon in maize production under higher plant density,which limits crop productivity.Subsoiling is an effective agronomic practice for improving crop productivity...The intensified kernel position effect is a common phenomenon in maize production under higher plant density,which limits crop productivity.Subsoiling is an effective agronomic practice for improving crop productivity.To clarify the effect of subsoiling before winter wheat on the kernel position effect of densely grown summer maize and its regulatory mechanism,field experiments were conducted during the 2020-2021 and 2021-2022 growing seasons using a split-plot design.The main plots included two tillage practices:conventional tillage practice(CT)and subsoiling before the sowing of winter wheat(SS);and the subplots consisted of three plant densities(D1-D3 at 6.0×10~4,7.5×10~4,and 9.0×10~4 plants ha-1).Compared with CT,SS alleviated the kernel position effect by increasing the weight ratio of inferior to superior kernels(WR)in the D2 and D3 treated plants.The higher WR of SS treated plants contributed largely to the improved flling of inferior kernels.Under the same plant density,SS signifcantly improved the root dry matter accumulation(DMA)and antioxidant enzyme activities(superoxide dismutase(SOD)and peroxidase(POD)),and it reduced the malondialdehyde(MDA)content,especially for the plants grown under higher plant densities.These results indicated that SS delayed the root senescence,which is associated with the reduced soil bulk density.In addition,compared with CT,SS increased the leaf chlorophyll content from 20 days after silking to physiological maturity and the post-silking leaf area duration,and it reduced the post-silking leaf chlorophyll reduction rate and leaf area reduction rate,indicating that the post-silking leaf senescence had been alleviated.Under the same plant density,the post-silking DMA of SS was obviously higher than that of CT,which was probably related to the improved leaf area duration and photosynthetic enzyme activities(phosphoenolpyruvate carboxylase(PEPC)and Rubisco).The correlation analysis revealed that the main mechanism of SS in alleviating the kernel position effect of densely grown summer maize is as follows:SS delays the post-silking root-shoot senescence by regulating soil physical properties,and further improves the post-silking DMA and flling of inferior kernels,which ultimately alleviates the kernel position effect and improves grain yield.The results of this study provide new theoretical support for the promotion of summer maize yield by subsoiling before winter wheat.展开更多
Based on the high-and low-resolution Community Earth System Model, version 1(CESM1), and corresponding simulations from phase 6 of the Coupled Model Intercomparison Project(CMIP6), we compare the interannual variabili...Based on the high-and low-resolution Community Earth System Model, version 1(CESM1), and corresponding simulations from phase 6 of the Coupled Model Intercomparison Project(CMIP6), we compare the interannual variability of the East Asian summer monsoon(EASM). The EASM interannual variability is characterized by the anomalous western North Pacific anticyclone(WNPAC) circulation and the dipole rainfall pattern with a negative southern lobe over the western North Pacific and a positive northern lobe along the Meiyu–Baiu region, which is better reproduced by the highresolution models. The reason for the improvement in the high-resolution models has been attributed to the better simulation of the warm temperature advection from the wind anomalies on the climatological temperature gradient. Positive sea surface temperature(SST) anomalies over the tropical Indian Ocean are the key to the improved wind anomalies featuring a WNPAC in the high-resolution models. The warm SST anomalies over the tropical Indian Ocean strengthen the WNPAC by triggering a Kelvin-wave response to the enhanced heat release induced by the increased precipitation. Based on the mixed-layer heat budget analysis, the warm SST anomalies over the western Indian Ocean in the high-resolution CESM1 are tied to the anomalous easterly wind along the equator, which reduces surface evaporation and upwelling.Therefore, the better simulations of air–sea feedback and the oceanic mesoscale eddy over the western Indian Ocean are the key for the improved simulation of the EASM interannual variations in the high-resolution CESM1.展开更多
The annual maximum rainfall event(AMRE)refers to the maximum consecutive five-day rainfall in a year.In North China,these events account for 15%–80%of the total summer(June–August)rainfall amount and pose a great ch...The annual maximum rainfall event(AMRE)refers to the maximum consecutive five-day rainfall in a year.In North China,these events account for 15%–80%of the total summer(June–August)rainfall amount and pose a great challenge for subseasonal-to-seasonal forecasting.Based on data analyses during 1979–2023,this study shows the interannual variability of AMRE is significantly influenced by the phase and amplitude mode of the annual cycle of the East Asian summer monsoon(EASM),characterized by two orthogonal patterns of southeasterly winds at 850 h Pa over the northwestern Pacific.The EASM phase-locked AMRE shows heavy rainfall events occurring extremely early and late in Beijing and surrounding areas,corresponding to the peak southeasterly wind anomalies in June and August.The EASM amplitude-locked AMRE exhibits extreme heavy or light rainfall over southwest areas with normal phase.Therefore,AMRE has a potential predictability on the seasonal time scale due to its phase-and amplitude-locking with the slow variation of the annual cycle of the EASM.展开更多
Based on a normalized difference vegetation index(NDVI)dataset for 1982-2021,this work investigates the principal modes of interannual variability in summer NDVI over eastern Siberia using the year-to-year increment m...Based on a normalized difference vegetation index(NDVI)dataset for 1982-2021,this work investigates the principal modes of interannual variability in summer NDVI over eastern Siberia using the year-to-year increment method and empirical orthogonal function(EOF)analysis.The first three principal modes(EOF1-3)of the year-to-year increment of summer NDVI(NDVI_DY)exhibit a regionally consistent mode,a western-eastern dipole mode,and a northern-southern dipole mode,respectively.Further analysis shows that sea surface temperature(SST)in the tropical Indian Ocean in February-March and western Siberian soil moisture in April could influence EOF1.EOF2 is modulated by April Northwest Pacific SST and western Siberian soil moisture in May.May North Atlantic SST and sea ice in the Kara Sea in the preceding October significantly affect EOF3.Using the year-to-year increment method and multiple linear regression analysis,prediction schemes for EOF1-3 are developed based on these predictors.To assess the predictive skill of these schemes,one-year-out cross-validation and independent hindcast methods are employed.The temporal correlation coefficients between observed EOF1-3 and the cross-validation results are 0.62,0.46,and 0.37,respectively,exceeding the 95%confidence level.In addition,reconstructed schemes for summer NDVI are developed using predicted NDVI_DY and the observed principal modes of NDVI_DY.Independent hindcasts of NDVI anomalies during 2019-2021 also present consistent distributions with the observed results.展开更多
The increase in frequency and intensity of Extreme High-temperature Events(EHEs)over Central-Eastern China(CEC)in recent decades has severely impacted social development and livelihoods.Using observation and reanalysi...The increase in frequency and intensity of Extreme High-temperature Events(EHEs)over Central-Eastern China(CEC)in recent decades has severely impacted social development and livelihoods.Using observation and reanalysis datasets,this study explores the effect of the East Asian subtropical westerly jet stream(EAJ)on the CEC EHEs for the summers spanning 1979–2020.Considering its general relative location to the right side of the upper-level jet stream exit region,CEC would theoretically suffer more EHEs with a stronger and northwardly-shifted EAJ in summer due to the likelihood of abnormal subsidence induced by the EAJ.However,such an EAJ–EHE connection has been unstable over the past four decades but has displayed an evident interdecadal change.Before the late 1990s,the interannual variation of the EAJ was manifested mainly by its meridional displacement in the northeastern part of East Asia;thus,the atmospheric responses were essentially located to the east of CEC,exerting less of an influence on the CEC EHEs.However,since the late 1990s,the EAJ variation has featured an intensity change in its center over the northwest portion of the CEC,which has resulted in a westward shift in atmospheric responses to cover the CEC region.Therefore,the EAJ could potentially affect the summer CEC EHEs during 2000–21.Our findings offer support for an in-depth understanding of the formation mechanisms of extreme weather/climate events of this nature and thus provide a scientific reference for seasonal climate predictions.展开更多
Many of us have the feeling: you step out in a T-shirt on a summer day, and within twenty minutes, your underarms feel damp. There are sweat marks on the clothes, and they are clearly visible. While many debate the me...Many of us have the feeling: you step out in a T-shirt on a summer day, and within twenty minutes, your underarms feel damp. There are sweat marks on the clothes, and they are clearly visible. While many debate the merits of polyester fabric with cool-touch feelingversus cotton as temperatures soar, the apparel world is quietly experiencing a "merino wool trend." A lot of major brands are launching merino wool short-sleeve tees.展开更多
This study explores the impact of the tropical sea surface temperature(SST) independent of the preceding winter El Nino–Southern Oscillation(ENSO) events(ENSO-independent SST) on the interannual variability of the So...This study explores the impact of the tropical sea surface temperature(SST) independent of the preceding winter El Nino–Southern Oscillation(ENSO) events(ENSO-independent SST) on the interannual variability of the South China Sea Summer Monsoon(SCSSM) and the associated mechanisms. During summer, the ENSO-independent SST component dominates across tropical ocean regions. The tropical ENSO-independent SSTs during spring and summer in the Maritime Continent(MC), the equatorial central-eastern Pacific(CEP), and the tropical Atlantic Ocean(TAO) regions play a comparably significant role in the interannual variation of the SCSSM intensity, compared to the tropical SST dependent on the preceding winter ENSO. The ENSO-independent SST anomalies(SSTA) in the TAO during spring and summer exhibit significant persistence. They can influence the SCSSM through westward propagation of teleconnection, as well as through eastward-propagating Kelvin waves. In summer, the SSTA in the MC, CEP, and TAO regions contribute jointly to the variability of the SCSSM. The MC SSTA affects local convection and generates anomalous meridional circulation to impact the SCSSM intensity. The CEP SSTA directly influences the SCSSM via the Matsuno-Gill response mechanism and indirectly affects it via meridional circulation by modulating vertical motions over the MC through zonal circulation. The TAO SSTA impacts the SCSSM through both westward and eastward pathways, as well as by influencing zonal circulation patterns in the tropical and subtropical North Pacific. The results offer valuable insights into the factors influencing the interannual variability of the SCSSM intensity.展开更多
The crystallinity has the potential to distinguish the primary and secondary calcite in Chinese loess, which then provides insights into illuviation depth and variations of the East Asian Summer Monsoon. However, this...The crystallinity has the potential to distinguish the primary and secondary calcite in Chinese loess, which then provides insights into illuviation depth and variations of the East Asian Summer Monsoon. However, this aspect has been rarely investigated. In this study, we defined the crystallinity of calcite as the height/area (H/A) ratio of the diffracted peak at crystal face (1 0 4). The H/A ratio inversely correlates with the average width of the diffracted peak, where a higher H/A ratio indicates higher crystallinity of calcite. Through the mixing and synthetic experiments, we found that the H/A ratio is minimally affected by factors such as calcite content, deposition temperature or rate but significantly influenced by the ionic impurity and the mixing proportion of different calcites. Subsequently, we examined desert samples of loess sources and loess carbonate nodules. Desert samples predominantly consist of primary calcite which inherits characteristics from cryptocrystalline limestone with high levels of ionic impurities resulting in low H/A ratio of 4.30 ± 0.51. In contrast, loess carbonate nodules contain abundant secondary calcite precipitated within soil interstices with low levels of ionic impurities leading to a significantly higher H/A ratio of 7.76 ± 0.82. Consequently, higher H/A ratios during interglacial periods compared to glacial periods are attributed to variations in relative proportions between primary and secondary calcite in loess sequences. The thickness, between the glacial-interglacial boundary and the depth where the H/A ratio starts to increase from the bottom to the top in the loess layer, can be used to indicate the illuviation depth of upper-soil carbonates and the intensity of the East Asian Summer Monsoon. This proxy can be further applied in long-term loess sequences to uncover the summer monsoon evolution.展开更多
East Asia is a region characterized by a typical monsoon climate,which is accompanied by strong precipitation with complex spatiotemporal variability during summer.Previous works have emphasized the impact of tropical...East Asia is a region characterized by a typical monsoon climate,which is accompanied by strong precipitation with complex spatiotemporal variability during summer.Previous works have emphasized the impact of tropical signals on extreme summer precipitation over East Asia,but the roles of the mid-high latitude cyclones are still unclear.Using a reanalysis dataset,this study discloses the synergistic influences of anomalous signals from different latitudes on the extreme precipitation event in the Beijing-Tianjin-Hebei(BTH)region during the summer of 2023.The main conclusions are obtained as follows:the decreased sea ice density caused more Arctic cyclones to generate at positions further west in the Barents Sea and the west of the Kara Sea and then move southeast to East Asia in 2023.Furthermore,the synergistic influences of the outward Arctic cyclones and anomalous signals from middle and low latitudes are discussed.First,the significant northward jump of the Western Pacific Subtropical High(WPSH)provid-ed the favorable condition of large-scale background circulation for summer precipitation in the BTH region in 2023.In addition,the southward intrusion of the Arctic cyclones and the mid-latitude zonal wave trains transported massive cold air to the BTH region.Subsequently,the cold air masses met with the warm moist air carried by the landfall typhoon‘Doksuri’,which generated strong fronts and triggered the extreme precipitation on July 29.However,another severe typhoon,‘Kanu’,generated and moved northward from the tropical Pacific,which caused the further northward shift of the WPSH and the termination of this persistent extreme precipitation on August 1.展开更多
This research analyzes the variations of the South Asian Summer Monsoon Rainfall Anomaly(SASMRA)between the first development year(Y0)and the following year(Y1)of all multi-year La Ni?a events from 1958 to 2022.During...This research analyzes the variations of the South Asian Summer Monsoon Rainfall Anomaly(SASMRA)between the first development year(Y0)and the following year(Y1)of all multi-year La Ni?a events from 1958 to 2022.During Y0,monsoon precipitation surpasses climatological values,presenting a tripole spatial pattern,whereas Y1 is characterized by below-normal precipitation with a dipole pattern.In certain regions,the difference in precipitation between Y0 and Y1 reaches up to 3 mm day–1.This work provides further insight into the key tropical ocean regions driving the precipitation distinction,and elucidates their coupling mechanisms with large-scale atmospheric circulation anomalies.Influenced by the development of earlier ocean-atmosphere anomaly patterns,the Tropical Indian Ocean and Western Pacific(TIO-WP)warming(cooling)is significant during the summer of Y0(Y1).The elevated sea surface temperature(SST)in Y0 supports an anomalous Western North Pacific(WNP)anticyclone via a Kelvin-wave-induced Ekman divergence mechanism.This anomalous anticyclone intensifies the suppressed convection over the WNP,which results in increased divergence in the upper-level troposphere over the Indian Ocean and South Asian regions,thereby boosting convection.Simultaneously,the easterly winds associated with the strengthened equatorial latitude SST anomaly(SSTA)gradient and the anomalous anticyclone intensified,transporting a large amount of water vapor to the west.The combined moisture and dynamic conditions support the enhanced precipitation in the South Asian region.展开更多
This study explores the impact of winter sea surface temperature(SST)anomalies in the Southern Indian Ocean on summer precipitation patterns in China,utilizing data from reanalysis sources and Coupled Model Intercompa...This study explores the impact of winter sea surface temperature(SST)anomalies in the Southern Indian Ocean on summer precipitation patterns in China,utilizing data from reanalysis sources and Coupled Model Intercomparison Project Phase 6(CMIP6)models.The results reveal that the Southern Indian Ocean Dipole(SIOD),characterized by contrasting SST anomalies in the northeast and southwest regions,acts as a predictor for Chinese summer precipitation patterns,namely floods in the south and drought in the north.In a positive SIOD event,the southwestern Indian Ocean exhibits warmer SSTs,while the northeastern region remains cooler.A negative SIOD event shows the opposite pattern.During the positive phase of the SIOD,the winter SST distribution strengthens the 850-hPa cross-equatorial airflow,generating a robust low-level westerly jet that enhances water vapor transport to the Bay of Bengal(BoB).These air-sea interactions maintain lower SSTs in the northeastern region,which significantly increase the land-sea temperature contrast in the Northern Hemisphere during spring and summer.This strengthened thermal gradient intensifies the southwest monsoon,establishing a strong convergence zone near the South China Sea and amplifying monsoon-driven precipitation in South China.Additionally,CMIP6 models,such as NorESM2-LM and NorCPM1,which accurately simulate the SIOD pattern,effectively capture the seasonal response of cross-equatorial airflow driven by SST anomalies of Southern Indian Ocean.The result highlights the essential role of cross-equatorial airflow generated by the SIOD in forecasting crossseasonal precipitation patterns.展开更多
基金supported by the National Natural Science Foundation of China[grant numbers 41975087,U2242212,and 41975085]supported by the National Natural Science Foundation of China[grant number U2242212]。
文摘Based on reanalysis data from 1979 to 2021,this study explores the spatial distribution of the Southern Indian Ocean Dipole(SIOD)and its individual and synergistic effects with the El Niño-Southern Oscillation(ENSO)on summer precipitation in China.The inverse phase spatial distribution of sea surface temperature anomalies(SSTAs)in the southwest and northeast of the southern Indian Ocean is defined as the SIOD.Positive SIOD events(positive SSTAs in the southwest,negative SSTAs in the northeast)are associated with La Niña events(Central Pacific(CP)type),while negative SIOD events(negative SSTAs in the southwest,positive SSTAs in the northeast)are associated with El Niño events(Eastern Pacific(EP)type).Both SIOD and ENSO have certain impacts on summer precipitation in China.Precipitation in the Yangtze River basin decreases,while precipitation in southern China increases during pure positive SIOD(P_PSIOD)events.During pure negative SIOD(P_NSIOD)events,the changes in precipitation are exactly the opposite of those during P_PSIOD events,which may be due to differences in the cross-equatorial flow in the southern Indian Ocean,particularly in low-level Australian cross-equatorial flow.When positive SIOD and CP-type La Niña events occur simultaneously(PSIOD+La_Niña),precipitation increases in the Yangtze-Huaihe River basin,while it decreases in northern China.When negative SIOD and EP-type El Niño events occur simultaneously(NSIOD+El_Niño),precipitation in the Yangtze-Huaihe River basin is significantly lower than during P_NSIOD events.This is caused by differences in water vapor originating from the Pacific Ocean during different events.
基金Supported by Ningxia Natural Science Foundation(2024AAC03100).
文摘Summer residential tourism is the future trend in China because of tourists’living quality improvement,heat crisis,rising market demand,and optimization of the destinations’residential environment,transport and accessibility.Compared with summer tourism and vacation tourism,summer residential tourism had got less attention and lacks in prospective and preventive research.Hence,this study focused on potential assessment,pattern recognition and phase segmentation of 32 residential tourism destinations in China selected from 4 lists.An index system of 16 indicators from 5 dimensions was established as Summer Residence Index(SRI),and Range method,Entropy weight method and Composite index method were chosen as the core methods.Three main conclusions were as follows.(1)Only 2 typical districts’SRI value were near to 0.6,and 4 destinations were below 0.1,about 26 destinations were at medium-level,which indicated that China’s summer residential tourism was not so popular and only few destinations have stepped into a higher level.(2)Seven patterns could be recognized based on the contribution of the 5 dimensions to SRI value,including 3 single-factor driven patterns and 4 compound factors driven patterns.(3)Like tourist area life cycle(TALC),Unconscious stage,Initial stage,Developmental stage and Maturity stage could be segmented for summer residential destinations with the value of below 0.1,0.1-0.3,0.3-0.5,and above 0.5.Four destinations were under Unconscious stage.Twenty-two destinations were at initiate stage.Only 4 destinations have stepped into development stage and 2 at maturity stage.China’summer residential tourism has just started and has a better prospect.This study is just an attempt and needs further consideration,for example,a tracking study of SRI calculation for each year will be carried to justify the effectiveness of SRI and to check the rationality of the empirical results.As time goes on,policies in housing,residential estate and other aspects should be included as a factor in the SRI index.Data availability should be optimized because of better data sources and new technologies.Some other districts or cities in 2 batches of national Comprehensive Tourism Demonstration Zones(CTDZs)pilots and provincial CTDZs will be further selections of summer residential tourism destinations.
基金supported by the National Natural Science Foundation of China [grant number 42088101]。
文摘During the boreal summer,intraseasonal oscillations exhibit significant interannual variations in intensity over two key regions:the central-western equatorial Pacific(5°S-5°N,150°E-150°W)and the subtropical Northwestern Pacific(10°-20°N,130°E-175°W).The former is well-documented and considered to be influenced by the ENSO,while the latter has received comparatively less attention and is likely influenced by the Pacific Meridional Mode(PMM),as suggested by partial correlation analysis results.To elucidate the physical processes responsible for the enhanced(weakened)intraseasonal convection over the subtropical northwestern Pacific during warm(cold)PMM years,the authors employed a moisture budget analysis.The findings reveal that during warm PMM years,there is an increase in summer-mean moisture over the subtropical northwestern Pacific.This increase interacts with intensified vertical motion perturbations in the region,leading to greater vertical moisture advection in the lower troposphere and consequently resulting in convective instability.Such a process is pivotal in amplifying intraseasonal convection anomalies.The observational findings were further verified by model experiments forced by PMM-like sea surface temperature patterns.
文摘Summer is my favorite season of the year.The weather is hot,but I don’t mind because there are so many fun things to do.In summer,I can swim in the pool with my friends.The cool water makes me feel really comfortable.
基金Supported by Special Project for the Construction of the National Modern Agricultural Industry Technology System(CARS-04-CES16).
文摘Soybeans are rich in protein,fats,vitamins,and minerals,serving as an important source of plant-based protein for humans.Summer soybean is widely cultivated in China,and improving its yield and quality is of great significance for ensuring food security and promoting agricultural economic development.This paper elaborated on the high-quality and high-yield cultivation techniques for summer soybean,including variety selection,seed treatment,field selection and land preparation,sowing techniques,field management,pest and disease control,and harvesting,aiming to provide scientific cultivation guidance for summer soybean growers to achieve both superior quality and high yield.
文摘Hello,everyone!I am Cici.I had a summer holiday that was both busy and happy.From July 11th to July 20th,I went to school every day to learn traditional Chinese painting.The soft brushes glided across the paper,creating beautiful and vivid images.
基金funded by the National Natural Science Foundation of China(Grant Nos.U21A6001,42261144687,42175173)the Project supported by Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant No.SML2023SP208)the GuangDong Basic and Applied Basic Research Foundation(2023A1515240036).
文摘Based on the C-Coupler platform,the semi-unstructured Climate System Model,Synthesis Community Integrated Model version 2(SYCIM2.0),has been developed at the School of Atmospheric Sciences,Sun Yat-sen University.SYCIM2.0 aims to meet the demand for seamless climate prediction through accurate climate simulations and projections.This paper provides an overview of SYCIM2.0 and highlights its key features,especially the coupling of an unstructured ocean model and the tuning process.An extensive evaluation of its performance,focusing on the East Asian Summer Monsoon(EASM),is presented based on long-term simulations with fixed external forcing.The results suggest that after nearly 240 years of integration,SYCIM2.0 achieves a quasi-equilibrium state,albeit with small trends in the net radiation flux at the top-of-atmosphere(TOA)and Earth’s surface,as well as with global mean near-surface temperatures.Compared to observational and reanalysis data,the model realistically simulates spatial patterns of sea surface temperature(SST)and precipitation centers to include their annual cycles,in addition to the lower-level wind fields in the EASM region.However,it exhibits a weakened and eastward-shifted Western Pacific Subtropical High(WPSH),resulting in an associated precipitation bias.SYCIM2.0 robustly captures the dominant mode of the EASM and its close relationship with the El Niño-Southern Oscillation(ENSO)but exhibits relatively poor performance in simulating the second leading mode and the associated air–sea interaction processes.Further comprehensive evaluations of SYCIM2.0 will be conducted in future studies.
基金supported by the National Natural Science Foundation of China(Grant No.42275025)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2023084).
文摘This study conducts a comparative investigation between short-lived(3-8 days)and long-lived(9-24 days)break events of the South China Sea summer monsoon during 1979-2020,focusing on their statistical characteristics and potential mechanisms for their different persistence.Results suggest that both types of events are characterized by anomalously suppressed convection accompanied by an anomalous anticyclone during the break period.However,these convection and circulation anomalies exhibit more localized patterns for short-lived events,but possess larger spatial scales and stronger intensities for long-lived events.The influence of tropical intraseasonal oscillations(ISOs)on short-and long-lived events is explored to interpret their different durations.It is found that for short-lived events,the 10-25-day oscillation is dominant in initiating and terminating the break,while the impact of the 30-60-day oscillation is secondary,thus resulting in a brief break period.In contrast,for long-lived events,the 10-25-day oscillation contributes to break development rather than its initiation,and concurrently,the 30-60-day oscillation shows a remarkable enhancement and plays a decisive role in prolonging the break duration.Furthermore,we find that long-lived events are preceded by significant ISO activities approximately two weeks before their occurrence,which can be regarded as efficient predictors.Associated with these precursory ISOs,the occurrence probability of break days for long-lived events can rise up to triple their original probability(35.43%vs.11.21%).
基金fnancially supported by the Natural Science Foundation of Hebei Province,China(C2021301004)the State Key Laboratory of North China Crop Improvement and Regulation,China(NCCIR2023KF-10)the HAAFS Science and Technology Innovation Special Project,China(2022KJCXZX-LYS-9)。
文摘The intensified kernel position effect is a common phenomenon in maize production under higher plant density,which limits crop productivity.Subsoiling is an effective agronomic practice for improving crop productivity.To clarify the effect of subsoiling before winter wheat on the kernel position effect of densely grown summer maize and its regulatory mechanism,field experiments were conducted during the 2020-2021 and 2021-2022 growing seasons using a split-plot design.The main plots included two tillage practices:conventional tillage practice(CT)and subsoiling before the sowing of winter wheat(SS);and the subplots consisted of three plant densities(D1-D3 at 6.0×10~4,7.5×10~4,and 9.0×10~4 plants ha-1).Compared with CT,SS alleviated the kernel position effect by increasing the weight ratio of inferior to superior kernels(WR)in the D2 and D3 treated plants.The higher WR of SS treated plants contributed largely to the improved flling of inferior kernels.Under the same plant density,SS signifcantly improved the root dry matter accumulation(DMA)and antioxidant enzyme activities(superoxide dismutase(SOD)and peroxidase(POD)),and it reduced the malondialdehyde(MDA)content,especially for the plants grown under higher plant densities.These results indicated that SS delayed the root senescence,which is associated with the reduced soil bulk density.In addition,compared with CT,SS increased the leaf chlorophyll content from 20 days after silking to physiological maturity and the post-silking leaf area duration,and it reduced the post-silking leaf chlorophyll reduction rate and leaf area reduction rate,indicating that the post-silking leaf senescence had been alleviated.Under the same plant density,the post-silking DMA of SS was obviously higher than that of CT,which was probably related to the improved leaf area duration and photosynthetic enzyme activities(phosphoenolpyruvate carboxylase(PEPC)and Rubisco).The correlation analysis revealed that the main mechanism of SS in alleviating the kernel position effect of densely grown summer maize is as follows:SS delays the post-silking root-shoot senescence by regulating soil physical properties,and further improves the post-silking DMA and flling of inferior kernels,which ultimately alleviates the kernel position effect and improves grain yield.The results of this study provide new theoretical support for the promotion of summer maize yield by subsoiling before winter wheat.
基金supported by the National Natural Science Foundation of China [Grant Nos.42275018 (L.D.) and 42175029 (F.S.)]the Shandong Provincial Natural Science Fund for Excellent Young Scientists Fund Program (Overseas) [Grant No.2022HWYQ-065 (L.D.)]+3 种基金the Taishan Scholars Program of Shandong Province [Grant No.tsqn202211068 (L.D.)]the Fund of Laoshan Laboratory [Grant Nos.LSKJ202202602 (L.D.) and LSKJ202202201 (F.S.)]financially supported by Laoshan Laboratory (Grant No.LSKJ202300302)supported by the Office of Science, U.S.Department of Energy (DOE) Biological and Environmental Research through the Water Cycle and Climate Extremes Modeling (WACCEM) scientific focus area funded by the Regional and Global Model Analysis program area。
文摘Based on the high-and low-resolution Community Earth System Model, version 1(CESM1), and corresponding simulations from phase 6 of the Coupled Model Intercomparison Project(CMIP6), we compare the interannual variability of the East Asian summer monsoon(EASM). The EASM interannual variability is characterized by the anomalous western North Pacific anticyclone(WNPAC) circulation and the dipole rainfall pattern with a negative southern lobe over the western North Pacific and a positive northern lobe along the Meiyu–Baiu region, which is better reproduced by the highresolution models. The reason for the improvement in the high-resolution models has been attributed to the better simulation of the warm temperature advection from the wind anomalies on the climatological temperature gradient. Positive sea surface temperature(SST) anomalies over the tropical Indian Ocean are the key to the improved wind anomalies featuring a WNPAC in the high-resolution models. The warm SST anomalies over the tropical Indian Ocean strengthen the WNPAC by triggering a Kelvin-wave response to the enhanced heat release induced by the increased precipitation. Based on the mixed-layer heat budget analysis, the warm SST anomalies over the western Indian Ocean in the high-resolution CESM1 are tied to the anomalous easterly wind along the equator, which reduces surface evaporation and upwelling.Therefore, the better simulations of air–sea feedback and the oceanic mesoscale eddy over the western Indian Ocean are the key for the improved simulation of the EASM interannual variations in the high-resolution CESM1.
基金jointly supported by the National Natural Science Foundation of China(Grant Nos.U2242205 and 42375033)the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant No.2019QZKK0105)+1 种基金the Basic Scientific Research and Operation Foundation of CAMS(2023Z018)the S&T Development Fund of CAMS(Grant No.2023KJ036)。
文摘The annual maximum rainfall event(AMRE)refers to the maximum consecutive five-day rainfall in a year.In North China,these events account for 15%–80%of the total summer(June–August)rainfall amount and pose a great challenge for subseasonal-to-seasonal forecasting.Based on data analyses during 1979–2023,this study shows the interannual variability of AMRE is significantly influenced by the phase and amplitude mode of the annual cycle of the East Asian summer monsoon(EASM),characterized by two orthogonal patterns of southeasterly winds at 850 h Pa over the northwestern Pacific.The EASM phase-locked AMRE shows heavy rainfall events occurring extremely early and late in Beijing and surrounding areas,corresponding to the peak southeasterly wind anomalies in June and August.The EASM amplitude-locked AMRE exhibits extreme heavy or light rainfall over southwest areas with normal phase.Therefore,AMRE has a potential predictability on the seasonal time scale due to its phase-and amplitude-locking with the slow variation of the annual cycle of the EASM.
基金supported by the National Key Research and Development Program of China[grant number 2022YFE0106800]the National Natural Science Foundation of China[grant number 42230603]+1 种基金the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)[grant number 311024001]supported by Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)[grant number SML2023SP209].
文摘Based on a normalized difference vegetation index(NDVI)dataset for 1982-2021,this work investigates the principal modes of interannual variability in summer NDVI over eastern Siberia using the year-to-year increment method and empirical orthogonal function(EOF)analysis.The first three principal modes(EOF1-3)of the year-to-year increment of summer NDVI(NDVI_DY)exhibit a regionally consistent mode,a western-eastern dipole mode,and a northern-southern dipole mode,respectively.Further analysis shows that sea surface temperature(SST)in the tropical Indian Ocean in February-March and western Siberian soil moisture in April could influence EOF1.EOF2 is modulated by April Northwest Pacific SST and western Siberian soil moisture in May.May North Atlantic SST and sea ice in the Kara Sea in the preceding October significantly affect EOF3.Using the year-to-year increment method and multiple linear regression analysis,prediction schemes for EOF1-3 are developed based on these predictors.To assess the predictive skill of these schemes,one-year-out cross-validation and independent hindcast methods are employed.The temporal correlation coefficients between observed EOF1-3 and the cross-validation results are 0.62,0.46,and 0.37,respectively,exceeding the 95%confidence level.In addition,reconstructed schemes for summer NDVI are developed using predicted NDVI_DY and the observed principal modes of NDVI_DY.Independent hindcasts of NDVI anomalies during 2019-2021 also present consistent distributions with the observed results.
基金supported by the Natural Science Foundation of China(Grant No:42105025,42075189,42275036,and 42430610)the National Key R&D Program of China under Grant 2021YFA0718000+3 种基金the China Meteorological Administration Youth Innovation Team(CMA2023QN15)China Meteorological Administration Key Innovation Team(CMA2024ZD07)the development fund of South China Sea Institute of Oceanology of the Chinese Academy of Sciences(SCSIO202203 and SCSIO202208)the Open Research Fund of the State Key Laboratory of Tropical Oceanography(South China Sea Institute of Oceanology,Chinese Academy of Sciences)(LTO2110)。
文摘The increase in frequency and intensity of Extreme High-temperature Events(EHEs)over Central-Eastern China(CEC)in recent decades has severely impacted social development and livelihoods.Using observation and reanalysis datasets,this study explores the effect of the East Asian subtropical westerly jet stream(EAJ)on the CEC EHEs for the summers spanning 1979–2020.Considering its general relative location to the right side of the upper-level jet stream exit region,CEC would theoretically suffer more EHEs with a stronger and northwardly-shifted EAJ in summer due to the likelihood of abnormal subsidence induced by the EAJ.However,such an EAJ–EHE connection has been unstable over the past four decades but has displayed an evident interdecadal change.Before the late 1990s,the interannual variation of the EAJ was manifested mainly by its meridional displacement in the northeastern part of East Asia;thus,the atmospheric responses were essentially located to the east of CEC,exerting less of an influence on the CEC EHEs.However,since the late 1990s,the EAJ variation has featured an intensity change in its center over the northwest portion of the CEC,which has resulted in a westward shift in atmospheric responses to cover the CEC region.Therefore,the EAJ could potentially affect the summer CEC EHEs during 2000–21.Our findings offer support for an in-depth understanding of the formation mechanisms of extreme weather/climate events of this nature and thus provide a scientific reference for seasonal climate predictions.
文摘Many of us have the feeling: you step out in a T-shirt on a summer day, and within twenty minutes, your underarms feel damp. There are sweat marks on the clothes, and they are clearly visible. While many debate the merits of polyester fabric with cool-touch feelingversus cotton as temperatures soar, the apparel world is quietly experiencing a "merino wool trend." A lot of major brands are launching merino wool short-sleeve tees.
基金National Natural Science Foundation of China(42175018, 42175020)Science and Technology Planning Project of Guangdong Province (2023B1212060019)+1 种基金Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai)(311024001)Project supported by Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai)(SML2023SP209)。
文摘This study explores the impact of the tropical sea surface temperature(SST) independent of the preceding winter El Nino–Southern Oscillation(ENSO) events(ENSO-independent SST) on the interannual variability of the South China Sea Summer Monsoon(SCSSM) and the associated mechanisms. During summer, the ENSO-independent SST component dominates across tropical ocean regions. The tropical ENSO-independent SSTs during spring and summer in the Maritime Continent(MC), the equatorial central-eastern Pacific(CEP), and the tropical Atlantic Ocean(TAO) regions play a comparably significant role in the interannual variation of the SCSSM intensity, compared to the tropical SST dependent on the preceding winter ENSO. The ENSO-independent SST anomalies(SSTA) in the TAO during spring and summer exhibit significant persistence. They can influence the SCSSM through westward propagation of teleconnection, as well as through eastward-propagating Kelvin waves. In summer, the SSTA in the MC, CEP, and TAO regions contribute jointly to the variability of the SCSSM. The MC SSTA affects local convection and generates anomalous meridional circulation to impact the SCSSM intensity. The CEP SSTA directly influences the SCSSM via the Matsuno-Gill response mechanism and indirectly affects it via meridional circulation by modulating vertical motions over the MC through zonal circulation. The TAO SSTA impacts the SCSSM through both westward and eastward pathways, as well as by influencing zonal circulation patterns in the tropical and subtropical North Pacific. The results offer valuable insights into the factors influencing the interannual variability of the SCSSM intensity.
基金funded by the National Natural Science Foundation of China(Nos.42173061,42473068).
文摘The crystallinity has the potential to distinguish the primary and secondary calcite in Chinese loess, which then provides insights into illuviation depth and variations of the East Asian Summer Monsoon. However, this aspect has been rarely investigated. In this study, we defined the crystallinity of calcite as the height/area (H/A) ratio of the diffracted peak at crystal face (1 0 4). The H/A ratio inversely correlates with the average width of the diffracted peak, where a higher H/A ratio indicates higher crystallinity of calcite. Through the mixing and synthetic experiments, we found that the H/A ratio is minimally affected by factors such as calcite content, deposition temperature or rate but significantly influenced by the ionic impurity and the mixing proportion of different calcites. Subsequently, we examined desert samples of loess sources and loess carbonate nodules. Desert samples predominantly consist of primary calcite which inherits characteristics from cryptocrystalline limestone with high levels of ionic impurities resulting in low H/A ratio of 4.30 ± 0.51. In contrast, loess carbonate nodules contain abundant secondary calcite precipitated within soil interstices with low levels of ionic impurities leading to a significantly higher H/A ratio of 7.76 ± 0.82. Consequently, higher H/A ratios during interglacial periods compared to glacial periods are attributed to variations in relative proportions between primary and secondary calcite in loess sequences. The thickness, between the glacial-interglacial boundary and the depth where the H/A ratio starts to increase from the bottom to the top in the loess layer, can be used to indicate the illuviation depth of upper-soil carbonates and the intensity of the East Asian Summer Monsoon. This proxy can be further applied in long-term loess sequences to uncover the summer monsoon evolution.
基金supported by the National Key Program for Developing Basic Science(Nos.2022YFE0106600 and 2022YFF0801702)the National Natural Science Foundation of China(No.42175060)+1 种基金the Jiangsu Province Science Foundation(No.BK20201259)the support of the Jiangsu Provincial Innovation Center for Climate Change.
文摘East Asia is a region characterized by a typical monsoon climate,which is accompanied by strong precipitation with complex spatiotemporal variability during summer.Previous works have emphasized the impact of tropical signals on extreme summer precipitation over East Asia,but the roles of the mid-high latitude cyclones are still unclear.Using a reanalysis dataset,this study discloses the synergistic influences of anomalous signals from different latitudes on the extreme precipitation event in the Beijing-Tianjin-Hebei(BTH)region during the summer of 2023.The main conclusions are obtained as follows:the decreased sea ice density caused more Arctic cyclones to generate at positions further west in the Barents Sea and the west of the Kara Sea and then move southeast to East Asia in 2023.Furthermore,the synergistic influences of the outward Arctic cyclones and anomalous signals from middle and low latitudes are discussed.First,the significant northward jump of the Western Pacific Subtropical High(WPSH)provid-ed the favorable condition of large-scale background circulation for summer precipitation in the BTH region in 2023.In addition,the southward intrusion of the Arctic cyclones and the mid-latitude zonal wave trains transported massive cold air to the BTH region.Subsequently,the cold air masses met with the warm moist air carried by the landfall typhoon‘Doksuri’,which generated strong fronts and triggered the extreme precipitation on July 29.However,another severe typhoon,‘Kanu’,generated and moved northward from the tropical Pacific,which caused the further northward shift of the WPSH and the termination of this persistent extreme precipitation on August 1.
基金Guangdong Major Project of Basic and Applied Basic Research(2020B0301030004)National Key Research and Development Program of China(2023YFF0805300)Civilian Space Programme of China(D040305)。
文摘This research analyzes the variations of the South Asian Summer Monsoon Rainfall Anomaly(SASMRA)between the first development year(Y0)and the following year(Y1)of all multi-year La Ni?a events from 1958 to 2022.During Y0,monsoon precipitation surpasses climatological values,presenting a tripole spatial pattern,whereas Y1 is characterized by below-normal precipitation with a dipole pattern.In certain regions,the difference in precipitation between Y0 and Y1 reaches up to 3 mm day–1.This work provides further insight into the key tropical ocean regions driving the precipitation distinction,and elucidates their coupling mechanisms with large-scale atmospheric circulation anomalies.Influenced by the development of earlier ocean-atmosphere anomaly patterns,the Tropical Indian Ocean and Western Pacific(TIO-WP)warming(cooling)is significant during the summer of Y0(Y1).The elevated sea surface temperature(SST)in Y0 supports an anomalous Western North Pacific(WNP)anticyclone via a Kelvin-wave-induced Ekman divergence mechanism.This anomalous anticyclone intensifies the suppressed convection over the WNP,which results in increased divergence in the upper-level troposphere over the Indian Ocean and South Asian regions,thereby boosting convection.Simultaneously,the easterly winds associated with the strengthened equatorial latitude SST anomaly(SSTA)gradient and the anomalous anticyclone intensified,transporting a large amount of water vapor to the west.The combined moisture and dynamic conditions support the enhanced precipitation in the South Asian region.
基金Guangdong Major Project of Basic and Applied Basic Research(2020B0301030004)National Natural Science Foundation of China(U2442202)+1 种基金Key Innovation Team of China Meteorological Administration“Climate Change Detection and Response”(CMA2022ZD03)National Key Research and Development Program of China(2023YFF0805104)。
文摘This study explores the impact of winter sea surface temperature(SST)anomalies in the Southern Indian Ocean on summer precipitation patterns in China,utilizing data from reanalysis sources and Coupled Model Intercomparison Project Phase 6(CMIP6)models.The results reveal that the Southern Indian Ocean Dipole(SIOD),characterized by contrasting SST anomalies in the northeast and southwest regions,acts as a predictor for Chinese summer precipitation patterns,namely floods in the south and drought in the north.In a positive SIOD event,the southwestern Indian Ocean exhibits warmer SSTs,while the northeastern region remains cooler.A negative SIOD event shows the opposite pattern.During the positive phase of the SIOD,the winter SST distribution strengthens the 850-hPa cross-equatorial airflow,generating a robust low-level westerly jet that enhances water vapor transport to the Bay of Bengal(BoB).These air-sea interactions maintain lower SSTs in the northeastern region,which significantly increase the land-sea temperature contrast in the Northern Hemisphere during spring and summer.This strengthened thermal gradient intensifies the southwest monsoon,establishing a strong convergence zone near the South China Sea and amplifying monsoon-driven precipitation in South China.Additionally,CMIP6 models,such as NorESM2-LM and NorCPM1,which accurately simulate the SIOD pattern,effectively capture the seasonal response of cross-equatorial airflow driven by SST anomalies of Southern Indian Ocean.The result highlights the essential role of cross-equatorial airflow generated by the SIOD in forecasting crossseasonal precipitation patterns.
