Under the background of significant climate warming since the 1980s, the glaciers in China＇s monsoonal temperate glacier region respond to the warming intensely. Based on the glaciohydrological observations at some t...Under the background of significant climate warming since the 1980s, the glaciers in China＇s monsoonal temperate glacier region respond to the warming intensely. Based on the glaciohydrological observations at some typical glaciers from Mts. Yulong （玉龙） and Gongga （贡嘎） of Hengduan （横断） Mountains Range in the southeastern Tibetan plateau, the glaciohydrological changes in the temperate glacier region since the 1980s were investigated. First, the glacier terminus exhibited an accelerating retreat. Second, as the glacier area subject to melting has increased and the ablation season has become longer due to the warming, the ablation of glacier enhanced, leading to increasing contribution of meltwater to annual river discharge. Third, surface topography of small temperate glacier may be changed significantly by crevasses and ruptures developed in the accumulation zone and ice collapse events in the ablation zone. The observed results may indicate a signal that the survival of glaciers in China＇s monsoonal temperate glacier region is being threatened by today＇s climate warming.展开更多
Geochemical and grain size analysis on the DQ （Dongqi） profile from Gonghe Basin, northeastern Qinghai-Tibetan Plateau, indi- cates that regional climate has experienced several cold-dry and warm-wet cycles since th...Geochemical and grain size analysis on the DQ （Dongqi） profile from Gonghe Basin, northeastern Qinghai-Tibetan Plateau, indi- cates that regional climate has experienced several cold-dry and warm-wet cycles since the last glacial maximum （LGM）. The cold and dry climate dominated the region before 15.82 cal. ka B.E due to stronger winter monsoon and weaker summer monsoon, but the climate was relatively cold and wetter prior to 21 cal. ka B.E. In 15.824.5 cal. ka B.E, summer monsoon strength in- creased and winter monsoon tended to be weaker, implying an obvious warm climate. Specifically, the relatively cold and dry condition appeared in 14.7-13.7 cal. ka B.E and 12.14.5 cal. ka B.R, respectively, while relatively warm and wet in 13.~12.1 cal. ka B.E. The winter and summer monsoonal strength presents frequent fluctuations in the Holocene and relatively warm and wet conditions emerged in 9.5~.0 cal. ka B.E due to stronger summer monsoon. From 7.0 to 5.1 cal. ka B.E, the cycle of cold-dry and warm-wet climate corresponds to frequent fluctuations of winter and summer monsoons. The climate becomes warm and wet in 5.1 2.7 cal. ka B.E, accompanying increased summer monsoon, but it tends to be cold and dry since 2.7 cal. ka B.R due to en- hanced winter monsoonal strength. In addition, the evolution of regional winter and summer monsoons is coincident with warm and cold records from the polar ice core. In other words, climatic change in the Gonghe Basin can be considered as a regional re- sponse to global climate change.展开更多
The question of possible teleconnections between the middle latitude general circulation and the Indian south-west monsoon was investigated in this paper. Within the framework of a simple model it was shown that there...The question of possible teleconnections between the middle latitude general circulation and the Indian south-west monsoon was investigated in this paper. Within the framework of a simple model it was shown that there can exist such an interaction via the ultra-long Rossby waves.展开更多
Evapotranspiration (ET) is an important part of the water cycle. This study reports on the monsoonal influence on the temporal variation in evapotranspiration of an extremely water conservative and salinity stressed t...Evapotranspiration (ET) is an important part of the water cycle. This study reports on the monsoonal influence on the temporal variation in evapotranspiration of an extremely water conservative and salinity stressed tropical mangrove forest at the land-ocean boundary of northeast coast of India. The magnitude and dynamics of evapotranspiration (ET) exhibited seasonality dominated by monsoon and evaporation rate was greater (0.055 ± 0.015 g·m-2·s-1) during the monsoon than in pre-monsoon (0.049 ± 0.018 g·m-2·s-1) and post-monsoon (0.044 ± 0.012 g·m-2·s-1). Seasonal difference in evapotranpiration was mostly due to fluctuation of canopy resistance, which was the minimum during monsoon when relative humidity was greater than in the dry season (pre- and post-monsoon) and deficiency of water supply (ET ≈ ETeq) was minimum. Evapotranspiration in the Sundarban mangrove ecosystem is the predominant biophysical processes that recycles 67.7% of total precipitation annually to the atmosphere, and has significant monsoonal influence.展开更多
The study is focused on hydrological response of a catchment to rainfall in extremely humid monsoonal climate region at the Meghalaya Plateau(India)near Cherrapunji.This area has been rarely investigated due to the la...The study is focused on hydrological response of a catchment to rainfall in extremely humid monsoonal climate region at the Meghalaya Plateau(India)near Cherrapunji.This area has been rarely investigated due to the lack of the detailed hydro-meteorological data.Hourly rainfall data were collected between 1999 and 2009 and hydrological data obtained for the Maw-Ki-Syiem experimental catchment(0.22 km^(2))was used to calibrate hydrological models(SCS-CN and GIUH)and to model river runoff during rainy periods in 2005.Hydrographs revealed rapid responses of the catchment to heavy rainfall.The rising limb and recession limb were very steep and coincided with hourly course of rainfall.展开更多
There is a wide diversity of landforms in China. The topography of three major ter- races, decreasing in height stepwise from west to east, was formed by the early Miocene. With the commencement of the Great Northern ...There is a wide diversity of landforms in China. The topography of three major ter- races, decreasing in height stepwise from west to east, was formed by the early Miocene. With the commencement of the Great Northern Hemisphere Glaciations （GHGs） and the glacial-interglacial cycles in the Pleistocene, thick loess deposits accumulated in north China, and fluvial terraces were formed and lakes expanded and contracted in eastern and central China. The earliest evidence of hominins in China is dated to ~1.7 Ma; they occupied the monsoon-dominated region for a long interval, until the late Pleistocene, ~50 ka. In this study, we investigated a large area rich in the relics and artifacts of early man. The results indicate that the early humans occupied riverine areas, especially medium-sized fluvial basins, and lake shores. Even in the relatively recent geological past, the occupation and abandonment of settlements were directly forced by the shifting of sand dune fields in the desert-loess transi- tional zone, which in turn was closely associated with variations in the monsoon climate and vegetation patterns. Our observations indicate that landforms were one of the main determi- nants of early human behavior, in that loess tableland, large alluvial plains, desert-Gobi areas, and the Tibetan Plateau, were not suitable environments for early human settlement. We infer that the early humans in China adapted their behavior to specific landforms and landform processes. The monsoon climate, which shapes the large-scale step-like pattern of fluvial landforms, promotes vegetation coverage and dominates soil formation, provides a crucial context for early human adaptation. The adaptation of early humans to earth surface proc- esses in East Asia is investigated for the first time in this study. Future investigations will provide further information that will increase our understanding of the linkage between early human behavior and landform processes in East Asia.展开更多
Summer monsoons （South Asian monsoon, South China Sea monsoon and Subtropical monsoon） are prominent features of summertime climate over southern China. Dif- ferent monsoons carry different inflow moisture into Chin...Summer monsoons （South Asian monsoon, South China Sea monsoon and Subtropical monsoon） are prominent features of summertime climate over southern China. Dif- ferent monsoons carry different inflow moisture into China and control the temporal and spatial distributions of precipitation. Analyses of meteorological data, particularly wind, tempera- ture and pressure anomalies are traditional methods of characterizing moisture sources and transport patterns. Here, we try to utilize the evidence from stable isotopes signatures to trace summer monsoons over southern China. Based on seven CHNIP （Chinese Network of Iso- topes in Precipitation） observatory stations located in southern China, monthly composite precipitation samples have been collected and analyzed for the composition of δ^18O during July, 2005. The results indicated that the spatial distributions of δ^18O in precipitation could properly portray the moisture sources together with their transport pathways. Moreover, the amount effect, altitude effect, temperature effect and the correlation between δ^18O vs. relative humidity were discussed.展开更多
A comparative analysis and quantitative diagnosis has been conducted of extreme rainfall associated with landfalling tropical cyclones(ERLTC)and non-extreme rainfall(NERLTC)using the dynamic composite analysis method....A comparative analysis and quantitative diagnosis has been conducted of extreme rainfall associated with landfalling tropical cyclones(ERLTC)and non-extreme rainfall(NERLTC)using the dynamic composite analysis method.Reanalysis data and the tropical cyclone precipitation dataset derived from the objective synoptic analysis technique were used.Results show that the vertically integrated water vapor transport(Q_(vt))during the ERLTC is significantly higher than that during the NERLTC.The Q_(vt)reaches a peak 1−2 days before the occurrence of the ERLTC and then decreases rapidly.There is a stronger convergence for both the Q_(vt)and the horizontal wind field during the ERLTC.The Q_(vt)convergence and the wind field convergence are mainly confined to the lower troposphere.The water vapor budget on the four boundaries of the tropical cyclone indicates that water vapor is input through all four boundaries before the occurrence of the ERLTC,whereas water vapor is output continuously from the northern boundary before the occurrence of the NERLTC.The water vapor inflow on both the western and southern boundaries of the ERLTC exceeds that during the NERLTC,mainly as a result of the different intensities of the southwest monsoonal surge in the surrounding environmental field.Within the background of the East Asian summer monsoon,the low-level jet accompanying the southwest monsoonal surge can increase the inflow of water vapor at both the western and southern boundaries during the ERLTC and therefore could enhance the convergence of the horizontal wind field and the water vapor flux,thereby resulting in the ERLTC.On the other hand,the southwest monsoonal surge decreases the zonal mean steering flow,which leads to a slower translation speed for the tropical cyclone associated with the ERLTC.Furthermore,a dynamic monsoon surge index(DMSI)defined here can be simply linked with the ERLTC and could be used as a new predictor for future operational forecasting of ERLTC.展开更多
Monsoon driven water mass exchange between the Bay of Bengal(Bo B) and Arabian Sea(AS) is the common experience. However, it is not yet firmly confirmed that the exchange pathway is either passing through southern tip...Monsoon driven water mass exchange between the Bay of Bengal(Bo B) and Arabian Sea(AS) is the common experience. However, it is not yet firmly confirmed that the exchange pathway is either passing through southern tip of Sri Lanka or Palk Strait. Local circulation patterns impact the pathways followed by the East Indian Coastal Currents(EICC) that drive exchange, thereby modulating mixing and water mass transformation in the Bay of Bengal around Sri Lanka. In this study, observations from surface drifters were incorporated with the satellite derived data to understand the monsoonal impact on circulation patterns in the Indian Ocean. This was the first multi-national scientific effort which was conducted in the Bo B and AS during 2013 to 2015 to understand the monsoonal impact on circulation patterns in the complex region. The results indicated that seasonally reversing monsoonal currents of southern Sri Lanka, traced by the wintertime freshwater export pathways of the EICC. The deflection of monsoon currents running along the east coast of Sri Lanka by forming cyclonic and anti-cyclonic eddies, which influence the mixing and stirring associated with these flows. Results further indicate the low salinity cold water flows from the Bo B to AS along the western boundary of the Bo B during northeast monsoon. In the same way, reverses the phenomena during southwest monsoon, transporting high salinity warm water from AS to the Bo B. This maintain the bay status which occurred due to freshwater influx from large rivers and high saline water from AS. However, no evidences were observed for the exchange through Palk Strait during the study.Also, there are some mis-matches in in-situ and remotely sensed measurements which imply the necessity of systematic observation system for the complex region as an alternative approach.展开更多
Phytoplankton species composition and abundance in the Lembeh Strait waters was studied in four cruises of April 2013, May 2014, June 2012 and October 2015, during the period of monsoon transition time of SE monsoon.W...Phytoplankton species composition and abundance in the Lembeh Strait waters was studied in four cruises of April 2013, May 2014, June 2012 and October 2015, during the period of monsoon transition time of SE monsoon.With data obtained the seasonal alternations of phytoplankton community structures and its driving factors were discussed. A total of 416 taxa belonging to 5 classes of phytoplankton were recorded in the four month surveys.Phytoplankton density was averaged 2 348 cell/L and diatoms and dinoflagellates had the most diversified species. Cyanobacterium was characterized by its low species numbers but high abundance in the waters of Lembeh Strait. Total phytoplankton abundance occurred low in April and October in the monsoon transition period and it raised high in May and June during the SE monsoon. Frequently occurred species were pelagic diatoms in addition to cyanobacterium Trichodesmium. Abundance and diversity of phytoplankton significantly differed seasonally. The diatoms Thalassionema and Pseudo-nitzschia, and cyanobacterium Trichodesmium contributed most to the community dissimilarities. Due to potentially higher nutrient supply in the south of Lembeh Strait, diatoms and dinoflagellates showed higher densities in the south than in the north of the strait.Though, cyanobacterium preferred distributing much evenly in all waters, it had higher density in the southern Lembeh Strait. Total phytoplankton abundance is quite low compared with the Jakarta Bay and some bays in China. Analysis showed that nutrients from upwelling forced by SE monsoon are the key factor varying the monthly phytoplankton abundances. Due to its primitive nature state, Lembeh water can be an ideal location for the study of pelagic ecosystem under merely the influence of macro environment changes with lower background noise from human activities.展开更多
An extreme monsoonal heavy rainfall event lasted for nine days and recurred in the interior of northern south China from June 13 to 21,2022.Using regional meteorological stations and ERA5 reanalysis data,the causes of...An extreme monsoonal heavy rainfall event lasted for nine days and recurred in the interior of northern south China from June 13 to 21,2022.Using regional meteorological stations and ERA5 reanalysis data,the causes of this extreme monsoonal rainfall event in south China were analyzed and diagnosed.The results are shown as follows.A dominant South Asian high tended to be stable near the Qinghai-Tibet Plateau,providing favorable upper-level dispersion conditions for the occurrence of heavy rainfall in south China.A western Pacific subtropical high dominated the eastern part of the South China Sea,favoring stronger and more northward transport of water vapor to the northern part of south China at lower latitudes than normal.The continuous heavy precipitation event can be divided into two stages.The first stage(June 13-15)was the frontal heavy rainfall caused by cold air(brought by an East Asian trough)from the mid-latitudes that converged with a monsoonal airflow.The heavy rains occurred mostly in the area near a shear in front of the center of a synoptic-system-related low-level jet(SLLJ),and the jet stream and precipitation were strongest in the daytime.The second stage(June 16-21)was the warm-sector heavy rainfall caused by a South China Sea monsoonal low-level jet penetrating inland.The heavy rainfall occurred on the windward slope of the Nanling Mountains and in the northern part of a boundary layer jet(BLJ).The BLJ experienced five nighttime enhancements,corresponding well with the enhancement of the rainfall center,showing significant nighttime heavy rainfall characteristics.Finally,a conceptual diagram of inland-type warm-sector heavy rainfall in south China is summarized.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
Predicting monsoon climate is one of the major endeavors in climate science and is becoming increasingly challenging due to global warming. The accuracy of monsoon seasonal predictions significantly impacts the lives ...Predicting monsoon climate is one of the major endeavors in climate science and is becoming increasingly challenging due to global warming. The accuracy of monsoon seasonal predictions significantly impacts the lives of billions who depend on or are affected by monsoons, as it is essential for the water cycle, food security, ecology, disaster prevention, and the economy of monsoon regions. Given the extensive literature on Asian monsoon climate prediction, we limit our focus to reviewing the seasonal prediction and predictability of the Asian Summer Monsoon (ASM). However, much of this review is also relevant to monsoon predictions in other seasons and regions. Over the past two decades, considerable progress has been made in the seasonal forecasting of the ASM, driven by an enhanced understanding of the sources of predictability and the dynamics of seasonal variability, along with advanced development in sophisticated models and technologies. This review centers on advances in understanding the physical foundation for monsoon climate prediction (section 2), significant findings and insights into the primary and regional sources of predictability arising from feedback processes among various climate components (sections 3 and 4), the effects of global warming and external forcings on predictability (section 5), developments in seasonal prediction models and techniques (section 6), the challenges and limitations of monsoon climate prediction (section 7), and emerging research trends with suggestions for future directions (section 8). We hope this review will stimulate creative activities to enhance monsoon climate prediction.展开更多
The South China Sea winter monsoon(SCSWM),an integral component of the East Asian winter monsoon,connects extratropical and tropical regions.Utilizing ERA5 reanalysis and PAMIP simulations,the relationship between Arc...The South China Sea winter monsoon(SCSWM),an integral component of the East Asian winter monsoon,connects extratropical and tropical regions.Utilizing ERA5 reanalysis and PAMIP simulations,the relationship between Arctic sea ice and the SCSWM is investigated.The authors reveal that its strongest relationship with Arctic sea ice occurs in the North Pacific sector,i.e.,the Sea of Okhotsk and western Bering Sea.This link persists throughout the cold season,peaks when sea ice precedes the SCSWM by one month,and is independent of ENSO.North Pacific sea-ice loss weakens the meridional temperature gradient(MTG)and vertical wind shear in midlatitudes,reducing baroclinic eddy formation.Given the reduced zonal wind according to the thermal wind relation,the reduced wave activity flux in the upper troposphere must be balanced by equatorward wind based on the quasi-geostrophic momentum equation.This generates an anomalous meridional overturning circulation with descent and low-level divergence around 30°N,which intensifies the divergent component of the SCSWM.The divergent northerly anomalies also lead to cold advection and subtropical cooling.The enhanced MTG due to the subtropical cooling and weakened MTG due to high-latitude warming closely tied to reduced North Pacific sea ice displace the westerly jet southward,creating cyclonic shears over the North Pacific and intensifying the rotational component of the SCSWM.These findings establish North Pacific sea ice as a non-ENSO driver of the SCSWM,holding substantial implications for the predictability of the SCSWM.展开更多
In recent years,there has been an increasing need for climate information across diverse sectors of society.This demand has arisen from the necessity to adapt to and mitigate the impacts of climate variability and cha...In recent years,there has been an increasing need for climate information across diverse sectors of society.This demand has arisen from the necessity to adapt to and mitigate the impacts of climate variability and change.Likewise,this period has seen a significant increase in our understanding of the physical processes and mechanisms that drive precipitation and its variability across different regions of Africa.By leveraging a large volume of climate model outputs,numerous studies have investigated the model representation of African precipitation as well as underlying physical processes.These studies have assessed whether the physical processes are well depicted and whether the models are fit for informing mitigation and adaptation strategies.This paper provides a review of the progress in precipitation simulation overAfrica in state-of-the-science climate models and discusses the major issues and challenges that remain.展开更多
The Yangtze River,with a length of approximately 6300 km,holds the distinction of being the largest river in East Asia that empties into the Pacific Ocean.Its formation is intricately linked to regional tectonic activ...The Yangtze River,with a length of approximately 6300 km,holds the distinction of being the largest river in East Asia that empties into the Pacific Ocean.Its formation is intricately linked to regional tectonic activity and climate fluctuations.However,the exact timeline for the formation of the Yangtze River remains elusive.This study investigates the provenance of the Late Cenozoic strata in the Wangjiang Basin,situated in the Lower Yangtze River,through the application of detrital zircon U-Pb dating.Seven sand samples were analyzed,leading to the identification of new U-Pb detrital zircon ages(n=577).Our study reveals that the sand materials found in the Pliocene gravel beds of the Anqing Formation originate predominantly from the Yangtze River.The findings of our study,along with the provenance tracing of boreholes in the Yangtze River Basin and the shelf sea in East China,provide compelling evidence for the continuous presence of the Yangtze River throughout the Pliocene period.The development of the Yangtze River during the Pliocene is intricately connected to both the tectonic adjustments occurring at the southeastern margin of the Tibetan Plateau and the intensification of the Asian Monsoon.展开更多
Palaeowind regime is an important component for reconstructing palaeoclimate and understanding ancient global circulation.We applied the beach-ridge thickness technique(BTT)and the longshore-bar thickness technique(LT...Palaeowind regime is an important component for reconstructing palaeoclimate and understanding ancient global circulation.We applied the beach-ridge thickness technique(BTT)and the longshore-bar thickness technique(LTT)to reconstruct the Early Cretaceous palaeowind velocities based on depositional records of Tanan Depression in Northeast Asia.The thickness of beach ridges and nearshore bars is the most important parameter for applying the BTT and the LTT methods.We identified 22 beach ridges and 23 nearshore bars based on drilling cores and wireline-log data in the Tanan Depression.Palaeowind velocities calculated by using the LTT method ranged from 10.84 to 13.66 m/s,showing a narrower range than those calculated by using the BTT method(7.58–15.93 m/s).We further analyzed the underlying factors causing the difference between the results derived from these two methods based on the sedimentary process of the beach ridge and the nearshore bar.The reconstructed wind regime was assumed to be the summer monsoon originating from the Mongol-Okhotsk Ocean before it had been completely enclosed,which provides valuable insight into the understanding of the atmospheric circulation in Northeast Asia during the Early Cretaceous.展开更多
The Australian monsoon system plays a pivotal role in the tropical climate system by modulating the El Niño-Southern Oscillation(ENSO)development through multi-scale ocean-atmosphere interactions.This study ident...The Australian monsoon system plays a pivotal role in the tropical climate system by modulating the El Niño-Southern Oscillation(ENSO)development through multi-scale ocean-atmosphere interactions.This study identifies a significant decadal weakening of the Australian cross-equatorial flow intensity over the past two decades,attributed to the concurrent westward shift of the Australian High(AH)during austral winter.These decadal changes in the Australian monsoon reduce tropical Pacific atmospheric convection and the associated westerly wind anomalies over the centralto-western Pacific,which are crucial precursors for ENSO development.This process diminishes air-sea coupling feedback,including the thermocline feedback and the Ekman feedback,ultimately decreasing the strength of warm ENSO(El Niño)events.Using the Community Earth System Model,we confirm the close linkage between the Australian monsoon and ENSO on the decadal timescale.These findings provide new insights into the coupled relationship between ENSO and monsoon variability,offering a valuable framework for understanding ENSO’s longterm modulation and improving future climate predictions.展开更多
Urban flooding in low-lying coastal regions(LCRs)is intensifying due to climate change and sea-level rise;however,the complex interplay of hydrological,climatic,and anthropogenic drivers remains poorly understood.This...Urban flooding in low-lying coastal regions(LCRs)is intensifying due to climate change and sea-level rise;however,the complex interplay of hydrological,climatic,and anthropogenic drivers remains poorly understood.This study investigates the specific meteo-hydrological factors linking climate-induced changes and human activities to the urban flooding event in My Tho City,a vulnerable coastal city in Vietnam's Tien Giang Province,from February 9 to 12,2024.Analyzing historical meteo-hydrological data(rainfall,monsoon winds,river discharge,and water levels),we examined the contributing factors.Our findings reveal that the flooding was predominantly driven by the combination of high astronomical tidal levels and significant water surges.These surges were amplified by northeast monsoon circulation.This situation was compounded by critically low Mekong River discharge during the dry season,which enhanced the inland penetration of tidal effects.Rainfall during the period was minimal and did not contribute significantly.We utilized a filtering technique to differentiate between astronomical tides and non-tidal surges in the water level data.These results provide empirical evidence demonstrating that climate-driven sea-level influences(manifesting as high tides and surges)and anthropogenic alterations to river flow governed the urban flooding dynamics.The study underscores the urgent need for integrated adaptation solutions addressing the complex land-ocean interactions, particularly in the context ofclimate change and relative sea-level rise.展开更多
Active atmospheric convection on the monsoon coast is crucial for the Earth’s climate system.In particular,the upscale convective growth(UCG)from ordinary isolated convection to organized convective system is a key p...Active atmospheric convection on the monsoon coast is crucial for the Earth’s climate system.In particular,the upscale convective growth(UCG)from ordinary isolated convection to organized convective system is a key process causing severe weather,but its activities on the monsoon coast are less understood because of the lack of fine-resolution datasets.For the first time,we present the climatology of UCG on a typical monsoon coast using kilometer-mesh radar data from southern China.The UCG undergoes pronounced subseasonal and diurnal variations in the early-summer rainy season.The subseasonal UCG increase is attributed to the onshore flows shifting from easterlies in April to monsoon southwesterlies in June.UCG becomes vigorous following summer monsoon onset,with hotspots near windward coastal mountains.Daytime UCG first peaks near noontime along coastal land,where onshore flows are destabilized by boundary-layer heating and mountains.Afternoon inland peaks and off-coast minimums are recognized due to land–sea thermal contrast and sea-breeze circulation.Nighttime UCG is revived at the coast by nocturnally enhanced southerlies,followed by offshore activity as the convergence of land-breeze northerlies shifts seaward.The UCG thus responds strongly to changing atmospheric conditions,land heating/cooling,and thermally driven local circulations.Our results may help clarify the predictability of monsoon coastal convection.展开更多
基金supported by the West Light Foundation of Chinese Academy of Sciences (No.O828A11001)the Orientation Project of Chinese Academy of Sciences (No.KZCXZ-YW-317)China Postdoctoral Science Foundation (Nos.08R214147,20080440641)
文摘Under the background of significant climate warming since the 1980s, the glaciers in China＇s monsoonal temperate glacier region respond to the warming intensely. Based on the glaciohydrological observations at some typical glaciers from Mts. Yulong （玉龙） and Gongga （贡嘎） of Hengduan （横断） Mountains Range in the southeastern Tibetan plateau, the glaciohydrological changes in the temperate glacier region since the 1980s were investigated. First, the glacier terminus exhibited an accelerating retreat. Second, as the glacier area subject to melting has increased and the ablation season has become longer due to the warming, the ablation of glacier enhanced, leading to increasing contribution of meltwater to annual river discharge. Third, surface topography of small temperate glacier may be changed significantly by crevasses and ruptures developed in the accumulation zone and ice collapse events in the ablation zone. The observed results may indicate a signal that the survival of glaciers in China＇s monsoonal temperate glacier region is being threatened by today＇s climate warming.
基金funded by National Natural Science Foundation of China (Nos. 40971005 and 41271215)
文摘Geochemical and grain size analysis on the DQ （Dongqi） profile from Gonghe Basin, northeastern Qinghai-Tibetan Plateau, indi- cates that regional climate has experienced several cold-dry and warm-wet cycles since the last glacial maximum （LGM）. The cold and dry climate dominated the region before 15.82 cal. ka B.E due to stronger winter monsoon and weaker summer monsoon, but the climate was relatively cold and wetter prior to 21 cal. ka B.E. In 15.824.5 cal. ka B.E, summer monsoon strength in- creased and winter monsoon tended to be weaker, implying an obvious warm climate. Specifically, the relatively cold and dry condition appeared in 14.7-13.7 cal. ka B.E and 12.14.5 cal. ka B.R, respectively, while relatively warm and wet in 13.~12.1 cal. ka B.E. The winter and summer monsoonal strength presents frequent fluctuations in the Holocene and relatively warm and wet conditions emerged in 9.5~.0 cal. ka B.E due to stronger summer monsoon. From 7.0 to 5.1 cal. ka B.E, the cycle of cold-dry and warm-wet climate corresponds to frequent fluctuations of winter and summer monsoons. The climate becomes warm and wet in 5.1 2.7 cal. ka B.E, accompanying increased summer monsoon, but it tends to be cold and dry since 2.7 cal. ka B.R due to en- hanced winter monsoonal strength. In addition, the evolution of regional winter and summer monsoons is coincident with warm and cold records from the polar ice core. In other words, climatic change in the Gonghe Basin can be considered as a regional re- sponse to global climate change.
文摘The question of possible teleconnections between the middle latitude general circulation and the Indian south-west monsoon was investigated in this paper. Within the framework of a simple model it was shown that there can exist such an interaction via the ultra-long Rossby waves.
文摘Evapotranspiration (ET) is an important part of the water cycle. This study reports on the monsoonal influence on the temporal variation in evapotranspiration of an extremely water conservative and salinity stressed tropical mangrove forest at the land-ocean boundary of northeast coast of India. The magnitude and dynamics of evapotranspiration (ET) exhibited seasonality dominated by monsoon and evaporation rate was greater (0.055 ± 0.015 g·m-2·s-1) during the monsoon than in pre-monsoon (0.049 ± 0.018 g·m-2·s-1) and post-monsoon (0.044 ± 0.012 g·m-2·s-1). Seasonal difference in evapotranpiration was mostly due to fluctuation of canopy resistance, which was the minimum during monsoon when relative humidity was greater than in the dry season (pre- and post-monsoon) and deficiency of water supply (ET ≈ ETeq) was minimum. Evapotranspiration in the Sundarban mangrove ecosystem is the predominant biophysical processes that recycles 67.7% of total precipitation annually to the atmosphere, and has significant monsoonal influence.
文摘The study is focused on hydrological response of a catchment to rainfall in extremely humid monsoonal climate region at the Meghalaya Plateau(India)near Cherrapunji.This area has been rarely investigated due to the lack of the detailed hydro-meteorological data.Hourly rainfall data were collected between 1999 and 2009 and hydrological data obtained for the Maw-Ki-Syiem experimental catchment(0.22 km^(2))was used to calibrate hydrological models(SCS-CN and GIUH)and to model river runoff during rainy periods in 2005.Hydrographs revealed rapid responses of the catchment to heavy rainfall.The rising limb and recession limb were very steep and coincided with hourly course of rainfall.
基金Foundation： National Natural Science Foundation of China, No.41472138, No.41401220, No.41472026 The CAS Strate- gic Priority Research Program Grant B, No.XDPB05 The Ministry of Science and Technology of China, No.2016YFA0600503
文摘There is a wide diversity of landforms in China. The topography of three major ter- races, decreasing in height stepwise from west to east, was formed by the early Miocene. With the commencement of the Great Northern Hemisphere Glaciations （GHGs） and the glacial-interglacial cycles in the Pleistocene, thick loess deposits accumulated in north China, and fluvial terraces were formed and lakes expanded and contracted in eastern and central China. The earliest evidence of hominins in China is dated to ~1.7 Ma; they occupied the monsoon-dominated region for a long interval, until the late Pleistocene, ~50 ka. In this study, we investigated a large area rich in the relics and artifacts of early man. The results indicate that the early humans occupied riverine areas, especially medium-sized fluvial basins, and lake shores. Even in the relatively recent geological past, the occupation and abandonment of settlements were directly forced by the shifting of sand dune fields in the desert-loess transi- tional zone, which in turn was closely associated with variations in the monsoon climate and vegetation patterns. Our observations indicate that landforms were one of the main determi- nants of early human behavior, in that loess tableland, large alluvial plains, desert-Gobi areas, and the Tibetan Plateau, were not suitable environments for early human settlement. We infer that the early humans in China adapted their behavior to specific landforms and landform processes. The monsoon climate, which shapes the large-scale step-like pattern of fluvial landforms, promotes vegetation coverage and dominates soil formation, provides a crucial context for early human adaptation. The adaptation of early humans to earth surface proc- esses in East Asia is investigated for the first time in this study. Future investigations will provide further information that will increase our understanding of the linkage between early human behavior and landform processes in East Asia.
基金National Natural Science Foundation of China, No. 40671034 Foundation of Isotopes in Precipitation of Chinese Ecosystem Research Network The authors would like to acknowledge Synthesis Center of Chinese Ecosystem Research Center and National Meteorological Information Center, China Meteorological Administration for providing the meteorological data. We also thank Yang Jinrong and Yuan Jingjing for sample analysis. At the same time, sincerely appreciation is given to all the observatory field stations for the collection of precipitation samples and a tour of their facilities.
文摘Summer monsoons （South Asian monsoon, South China Sea monsoon and Subtropical monsoon） are prominent features of summertime climate over southern China. Dif- ferent monsoons carry different inflow moisture into China and control the temporal and spatial distributions of precipitation. Analyses of meteorological data, particularly wind, tempera- ture and pressure anomalies are traditional methods of characterizing moisture sources and transport patterns. Here, we try to utilize the evidence from stable isotopes signatures to trace summer monsoons over southern China. Based on seven CHNIP （Chinese Network of Iso- topes in Precipitation） observatory stations located in southern China, monthly composite precipitation samples have been collected and analyzed for the composition of δ^18O during July, 2005. The results indicated that the spatial distributions of δ^18O in precipitation could properly portray the moisture sources together with their transport pathways. Moreover, the amount effect, altitude effect, temperature effect and the correlation between δ^18O vs. relative humidity were discussed.
基金the National Science Foundation of China(Grant Nos.41775048,42030611)National Basic Research Program of China(Grant No.2015CB452804)the Open Grants of the State Key Laboratory of Severe Weather(Grant No.2020LASW-B06).
文摘A comparative analysis and quantitative diagnosis has been conducted of extreme rainfall associated with landfalling tropical cyclones(ERLTC)and non-extreme rainfall(NERLTC)using the dynamic composite analysis method.Reanalysis data and the tropical cyclone precipitation dataset derived from the objective synoptic analysis technique were used.Results show that the vertically integrated water vapor transport(Q_(vt))during the ERLTC is significantly higher than that during the NERLTC.The Q_(vt)reaches a peak 1−2 days before the occurrence of the ERLTC and then decreases rapidly.There is a stronger convergence for both the Q_(vt)and the horizontal wind field during the ERLTC.The Q_(vt)convergence and the wind field convergence are mainly confined to the lower troposphere.The water vapor budget on the four boundaries of the tropical cyclone indicates that water vapor is input through all four boundaries before the occurrence of the ERLTC,whereas water vapor is output continuously from the northern boundary before the occurrence of the NERLTC.The water vapor inflow on both the western and southern boundaries of the ERLTC exceeds that during the NERLTC,mainly as a result of the different intensities of the southwest monsoonal surge in the surrounding environmental field.Within the background of the East Asian summer monsoon,the low-level jet accompanying the southwest monsoonal surge can increase the inflow of water vapor at both the western and southern boundaries during the ERLTC and therefore could enhance the convergence of the horizontal wind field and the water vapor flux,thereby resulting in the ERLTC.On the other hand,the southwest monsoonal surge decreases the zonal mean steering flow,which leads to a slower translation speed for the tropical cyclone associated with the ERLTC.Furthermore,a dynamic monsoon surge index(DMSI)defined here can be simply linked with the ERLTC and could be used as a new predictor for future operational forecasting of ERLTC.
文摘Monsoon driven water mass exchange between the Bay of Bengal(Bo B) and Arabian Sea(AS) is the common experience. However, it is not yet firmly confirmed that the exchange pathway is either passing through southern tip of Sri Lanka or Palk Strait. Local circulation patterns impact the pathways followed by the East Indian Coastal Currents(EICC) that drive exchange, thereby modulating mixing and water mass transformation in the Bay of Bengal around Sri Lanka. In this study, observations from surface drifters were incorporated with the satellite derived data to understand the monsoonal impact on circulation patterns in the Indian Ocean. This was the first multi-national scientific effort which was conducted in the Bo B and AS during 2013 to 2015 to understand the monsoonal impact on circulation patterns in the complex region. The results indicated that seasonally reversing monsoonal currents of southern Sri Lanka, traced by the wintertime freshwater export pathways of the EICC. The deflection of monsoon currents running along the east coast of Sri Lanka by forming cyclonic and anti-cyclonic eddies, which influence the mixing and stirring associated with these flows. Results further indicate the low salinity cold water flows from the Bo B to AS along the western boundary of the Bo B during northeast monsoon. In the same way, reverses the phenomena during southwest monsoon, transporting high salinity warm water from AS to the Bo B. This maintain the bay status which occurred due to freshwater influx from large rivers and high saline water from AS. However, no evidences were observed for the exchange through Palk Strait during the study.Also, there are some mis-matches in in-situ and remotely sensed measurements which imply the necessity of systematic observation system for the complex region as an alternative approach.
基金The China-Indonesia Maritime Cooperation Fund Project "China-Indonesia Bitung Ecological Station Establishment"
文摘Phytoplankton species composition and abundance in the Lembeh Strait waters was studied in four cruises of April 2013, May 2014, June 2012 and October 2015, during the period of monsoon transition time of SE monsoon.With data obtained the seasonal alternations of phytoplankton community structures and its driving factors were discussed. A total of 416 taxa belonging to 5 classes of phytoplankton were recorded in the four month surveys.Phytoplankton density was averaged 2 348 cell/L and diatoms and dinoflagellates had the most diversified species. Cyanobacterium was characterized by its low species numbers but high abundance in the waters of Lembeh Strait. Total phytoplankton abundance occurred low in April and October in the monsoon transition period and it raised high in May and June during the SE monsoon. Frequently occurred species were pelagic diatoms in addition to cyanobacterium Trichodesmium. Abundance and diversity of phytoplankton significantly differed seasonally. The diatoms Thalassionema and Pseudo-nitzschia, and cyanobacterium Trichodesmium contributed most to the community dissimilarities. Due to potentially higher nutrient supply in the south of Lembeh Strait, diatoms and dinoflagellates showed higher densities in the south than in the north of the strait.Though, cyanobacterium preferred distributing much evenly in all waters, it had higher density in the southern Lembeh Strait. Total phytoplankton abundance is quite low compared with the Jakarta Bay and some bays in China. Analysis showed that nutrients from upwelling forced by SE monsoon are the key factor varying the monthly phytoplankton abundances. Due to its primitive nature state, Lembeh water can be an ideal location for the study of pelagic ecosystem under merely the influence of macro environment changes with lower background noise from human activities.
基金National Natural Science Foundation of China(42075014)Science and Technology Key Project of Guangdong Meteorological Bureau(GRMC2020Z02,GRMCGS202101)+1 种基金Natural Science Foundation of Guangdong Province,China(2021A1515011539)Forecasters Project of China Meteorological Administration(CMAYBY2019-080)。
文摘An extreme monsoonal heavy rainfall event lasted for nine days and recurred in the interior of northern south China from June 13 to 21,2022.Using regional meteorological stations and ERA5 reanalysis data,the causes of this extreme monsoonal rainfall event in south China were analyzed and diagnosed.The results are shown as follows.A dominant South Asian high tended to be stable near the Qinghai-Tibet Plateau,providing favorable upper-level dispersion conditions for the occurrence of heavy rainfall in south China.A western Pacific subtropical high dominated the eastern part of the South China Sea,favoring stronger and more northward transport of water vapor to the northern part of south China at lower latitudes than normal.The continuous heavy precipitation event can be divided into two stages.The first stage(June 13-15)was the frontal heavy rainfall caused by cold air(brought by an East Asian trough)from the mid-latitudes that converged with a monsoonal airflow.The heavy rains occurred mostly in the area near a shear in front of the center of a synoptic-system-related low-level jet(SLLJ),and the jet stream and precipitation were strongest in the daytime.The second stage(June 16-21)was the warm-sector heavy rainfall caused by a South China Sea monsoonal low-level jet penetrating inland.The heavy rainfall occurred on the windward slope of the Nanling Mountains and in the northern part of a boundary layer jet(BLJ).The BLJ experienced five nighttime enhancements,corresponding well with the enhancement of the rainfall center,showing significant nighttime heavy rainfall characteristics.Finally,a conceptual diagram of inland-type warm-sector heavy rainfall in south China is summarized.
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supported by the National Natural Science Foundation of China(Grant No.U2342208)support from NSF/Climate Dynamics Award#2025057。
文摘Predicting monsoon climate is one of the major endeavors in climate science and is becoming increasingly challenging due to global warming. The accuracy of monsoon seasonal predictions significantly impacts the lives of billions who depend on or are affected by monsoons, as it is essential for the water cycle, food security, ecology, disaster prevention, and the economy of monsoon regions. Given the extensive literature on Asian monsoon climate prediction, we limit our focus to reviewing the seasonal prediction and predictability of the Asian Summer Monsoon (ASM). However, much of this review is also relevant to monsoon predictions in other seasons and regions. Over the past two decades, considerable progress has been made in the seasonal forecasting of the ASM, driven by an enhanced understanding of the sources of predictability and the dynamics of seasonal variability, along with advanced development in sophisticated models and technologies. This review centers on advances in understanding the physical foundation for monsoon climate prediction (section 2), significant findings and insights into the primary and regional sources of predictability arising from feedback processes among various climate components (sections 3 and 4), the effects of global warming and external forcings on predictability (section 5), developments in seasonal prediction models and techniques (section 6), the challenges and limitations of monsoon climate prediction (section 7), and emerging research trends with suggestions for future directions (section 8). We hope this review will stimulate creative activities to enhance monsoon climate prediction.
基金supported by the National Key Research and Development Program of China[grant number 2022YFF0801701]the National Natural Science Foundation of China[grant number 42105017].
文摘The South China Sea winter monsoon(SCSWM),an integral component of the East Asian winter monsoon,connects extratropical and tropical regions.Utilizing ERA5 reanalysis and PAMIP simulations,the relationship between Arctic sea ice and the SCSWM is investigated.The authors reveal that its strongest relationship with Arctic sea ice occurs in the North Pacific sector,i.e.,the Sea of Okhotsk and western Bering Sea.This link persists throughout the cold season,peaks when sea ice precedes the SCSWM by one month,and is independent of ENSO.North Pacific sea-ice loss weakens the meridional temperature gradient(MTG)and vertical wind shear in midlatitudes,reducing baroclinic eddy formation.Given the reduced zonal wind according to the thermal wind relation,the reduced wave activity flux in the upper troposphere must be balanced by equatorward wind based on the quasi-geostrophic momentum equation.This generates an anomalous meridional overturning circulation with descent and low-level divergence around 30°N,which intensifies the divergent component of the SCSWM.The divergent northerly anomalies also lead to cold advection and subtropical cooling.The enhanced MTG due to the subtropical cooling and weakened MTG due to high-latitude warming closely tied to reduced North Pacific sea ice displace the westerly jet southward,creating cyclonic shears over the North Pacific and intensifying the rotational component of the SCSWM.These findings establish North Pacific sea ice as a non-ENSO driver of the SCSWM,holding substantial implications for the predictability of the SCSWM.
基金the World Climate Research Programme(WCRP),Climate Variability and Predictability(CLIVAR),and Global Energy and Water Exchanges(GEWEX)for facilitating the coordination of African monsoon researchsupport from the Center for Earth System Modeling,Analysis,and Data at the Pennsylvania State Universitythe support of the Office of Science of the U.S.Department of Energy Biological and Environmental Research as part of the Regional&Global Model Analysis(RGMA)program area。
文摘In recent years,there has been an increasing need for climate information across diverse sectors of society.This demand has arisen from the necessity to adapt to and mitigate the impacts of climate variability and change.Likewise,this period has seen a significant increase in our understanding of the physical processes and mechanisms that drive precipitation and its variability across different regions of Africa.By leveraging a large volume of climate model outputs,numerous studies have investigated the model representation of African precipitation as well as underlying physical processes.These studies have assessed whether the physical processes are well depicted and whether the models are fit for informing mitigation and adaptation strategies.This paper provides a review of the progress in precipitation simulation overAfrica in state-of-the-science climate models and discusses the major issues and challenges that remain.
基金supported by the National Natural Science Foundation of China(Nos.42030305W2411033)Research Foundation of Chutian Scholars Program of Hubei Province(No.8210403)。
文摘The Yangtze River,with a length of approximately 6300 km,holds the distinction of being the largest river in East Asia that empties into the Pacific Ocean.Its formation is intricately linked to regional tectonic activity and climate fluctuations.However,the exact timeline for the formation of the Yangtze River remains elusive.This study investigates the provenance of the Late Cenozoic strata in the Wangjiang Basin,situated in the Lower Yangtze River,through the application of detrital zircon U-Pb dating.Seven sand samples were analyzed,leading to the identification of new U-Pb detrital zircon ages(n=577).Our study reveals that the sand materials found in the Pliocene gravel beds of the Anqing Formation originate predominantly from the Yangtze River.The findings of our study,along with the provenance tracing of boreholes in the Yangtze River Basin and the shelf sea in East China,provide compelling evidence for the continuous presence of the Yangtze River throughout the Pliocene period.The development of the Yangtze River during the Pliocene is intricately connected to both the tectonic adjustments occurring at the southeastern margin of the Tibetan Plateau and the intensification of the Asian Monsoon.
基金Supported by the National Science and Technology Special Project of China(No.2017ZX05009-002)the China Scholarship Council(No.202106400055)。
文摘Palaeowind regime is an important component for reconstructing palaeoclimate and understanding ancient global circulation.We applied the beach-ridge thickness technique(BTT)and the longshore-bar thickness technique(LTT)to reconstruct the Early Cretaceous palaeowind velocities based on depositional records of Tanan Depression in Northeast Asia.The thickness of beach ridges and nearshore bars is the most important parameter for applying the BTT and the LTT methods.We identified 22 beach ridges and 23 nearshore bars based on drilling cores and wireline-log data in the Tanan Depression.Palaeowind velocities calculated by using the LTT method ranged from 10.84 to 13.66 m/s,showing a narrower range than those calculated by using the BTT method(7.58–15.93 m/s).We further analyzed the underlying factors causing the difference between the results derived from these two methods based on the sedimentary process of the beach ridge and the nearshore bar.The reconstructed wind regime was assumed to be the summer monsoon originating from the Mongol-Okhotsk Ocean before it had been completely enclosed,which provides valuable insight into the understanding of the atmospheric circulation in Northeast Asia during the Early Cretaceous.
基金The National Natural Science Foundation of China under contract Nos 42105052 and 42376016the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)under contract No.SML2024SP012.
文摘The Australian monsoon system plays a pivotal role in the tropical climate system by modulating the El Niño-Southern Oscillation(ENSO)development through multi-scale ocean-atmosphere interactions.This study identifies a significant decadal weakening of the Australian cross-equatorial flow intensity over the past two decades,attributed to the concurrent westward shift of the Australian High(AH)during austral winter.These decadal changes in the Australian monsoon reduce tropical Pacific atmospheric convection and the associated westerly wind anomalies over the centralto-western Pacific,which are crucial precursors for ENSO development.This process diminishes air-sea coupling feedback,including the thermocline feedback and the Ekman feedback,ultimately decreasing the strength of warm ENSO(El Niño)events.Using the Community Earth System Model,we confirm the close linkage between the Australian monsoon and ENSO on the decadal timescale.These findings provide new insights into the coupled relationship between ENSO and monsoon variability,offering a valuable framework for understanding ENSO’s longterm modulation and improving future climate predictions.
基金supported by the Vietnam National University,Ho Chi Minh City(VNU-HCM)project entitled“Identifying and quantifying drivers causing water level fluctuations in the Vietnamese Mekong Delta”grant number[B2024-18-01].
文摘Urban flooding in low-lying coastal regions(LCRs)is intensifying due to climate change and sea-level rise;however,the complex interplay of hydrological,climatic,and anthropogenic drivers remains poorly understood.This study investigates the specific meteo-hydrological factors linking climate-induced changes and human activities to the urban flooding event in My Tho City,a vulnerable coastal city in Vietnam's Tien Giang Province,from February 9 to 12,2024.Analyzing historical meteo-hydrological data(rainfall,monsoon winds,river discharge,and water levels),we examined the contributing factors.Our findings reveal that the flooding was predominantly driven by the combination of high astronomical tidal levels and significant water surges.These surges were amplified by northeast monsoon circulation.This situation was compounded by critically low Mekong River discharge during the dry season,which enhanced the inland penetration of tidal effects.Rainfall during the period was minimal and did not contribute significantly.We utilized a filtering technique to differentiate between astronomical tides and non-tidal surges in the water level data.These results provide empirical evidence demonstrating that climate-driven sea-level influences(manifesting as high tides and surges)and anthropogenic alterations to river flow governed the urban flooding dynamics.The study underscores the urgent need for integrated adaptation solutions addressing the complex land-ocean interactions, particularly in the context ofclimate change and relative sea-level rise.
基金the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030004)the National Natural Science Foundation of China(Grant Nos.42275002 and 42275006)+1 种基金the National Institute of Natural Hazards,Ministry of Emergency Management of China(Grant Nos.ZDJ2024-01 and ZDJ2024-25)the Science and Technology Planning Project of Guangdong Province(Grant No.2023B1212060019).
文摘Active atmospheric convection on the monsoon coast is crucial for the Earth’s climate system.In particular,the upscale convective growth(UCG)from ordinary isolated convection to organized convective system is a key process causing severe weather,but its activities on the monsoon coast are less understood because of the lack of fine-resolution datasets.For the first time,we present the climatology of UCG on a typical monsoon coast using kilometer-mesh radar data from southern China.The UCG undergoes pronounced subseasonal and diurnal variations in the early-summer rainy season.The subseasonal UCG increase is attributed to the onshore flows shifting from easterlies in April to monsoon southwesterlies in June.UCG becomes vigorous following summer monsoon onset,with hotspots near windward coastal mountains.Daytime UCG first peaks near noontime along coastal land,where onshore flows are destabilized by boundary-layer heating and mountains.Afternoon inland peaks and off-coast minimums are recognized due to land–sea thermal contrast and sea-breeze circulation.Nighttime UCG is revived at the coast by nocturnally enhanced southerlies,followed by offshore activity as the convergence of land-breeze northerlies shifts seaward.The UCG thus responds strongly to changing atmospheric conditions,land heating/cooling,and thermally driven local circulations.Our results may help clarify the predictability of monsoon coastal convection.
