Time-lagged Effects of the Spring Atmospheric Heat Source over the Tibetan Plateau on Summer Precipitation in Northeast China during 1961–2020:Role of Soil Moisture

The spring atmospheric heat source(AHS)over the Tibetan Plateau(TP)has been suggested to affect the Asian summer monsoon and summer precipitation over South China.However,its influence on the summer precipitation in Northeast China(NEC)remains unknown.The connection between spring TP AHS and subsequent summer precipitation over NEC from 1961 to 2020 is analyzed in this study.Results illustrate that stronger spring TP AHS can enhance subsequent summer NEC precipitation,and higher soil moisture in the Yellow River Valley-North China region(YRVNC)acts as a bridge.During spring,the strong TP AHS could strengthen the transportation of water vapor to East China and lead to excessive rainfall in the YRVNC.Thus,soil moisture increases,which regulates local thermal conditions by decreasing local surface skin temperature and sensible heat.Owing to the memory of soil moisture,the lower spring sensible heat over the YRVNC can last until mid-summer,decrease the land–sea thermal contrast,and weaken the southerly winds over the East Asia–western Pacific region and convective activities over the South China Sea and tropical western Pacific.This modulates the East Asia–Pacific teleconnection pattern,which leads to a cyclonic anomaly and excessive summer precipitation over NEC.

Interdecadal variability of summer precipitation in the Three River Source Region: Influences of SST and zonal shifts of the East Asian subtropical westerly jet

Summer precipitation in the Three Rivers Source Region(TRSR)of China is vital for the headwaters of the Yellow,Yangtze,and Lancang rivers and exhibits significant interdecadal variability.This study investigates the influence of the East Asian westerly jet(EAWJ)on TRSR rainfall.A strong correlation is found between TRSR summer precipitation and the Jet Zonal Position Index(JZPI)of the EAWJ from 1961 to 2019(R=0.619,p<0.01).During periods when a positive JZPI indicates a westward shift in the EAWJ,enhanced water vapor anomalies,warmer air,and low-level convergence anomalies contribute to increased TRSR summer precipitation.Using empirical orthogonal function and regression analyses,this research identifies the influence of large-scale circulation anomalies associated with the Atlantic–Eurasian teleconnection(AEA)from the North Atlantic(NA).The interdecadal variability between the NA and central tropical Pacific(CTP)significantly affects TRSR precipitation.This influence is mediated through the AEA via a Rossby wave train extending eastward along the EAWJ,and another south of 45°N.Moreover,the NA–CTP Opposite Phase Index(OPI),which quantifies the difference between the summer mean sea surface temperatures of the NA and the CTP,is identified as a critical factor in modulating the strength of this teleconnection and influencing the zonal position of the EAWJ.

Enhanced Cooling Efficiency of Urban Trees on Hotter Summer Days in 70 Cities of China

Increasing the urban tree cover percentage(TCP) is widely recognized as an efficient way to mitigate the urban heat island effect. The cooling efficiency of urban trees can be either enhanced or attenuated on hotter days, depending on the physiological response of urban trees to rising ambient temperature. However, the response of urban trees' cooling efficiency to rising urban temperature remains poorly quantified for China's cities. In this study, we quantify the response of urban trees' cooling efficiency to rising urban temperature at noontime [~1330 LT(local time), LT=UTC+8] in 17summers(June, July, and August) from 2003–19 in 70 economically developed cities of China based on satellite observations. The results show that urban trees have stronger cooling efficiency with increasing temperature, suggesting additional cooling benefits provided by urban trees on hotter days. The enhanced cooling efficiency values of urban trees range from 0.002 to 0.055℃ %-1 per 1℃ increase in temperature across the selected cities, with larger values for the lowTCP-level cities. The response is also regulated by background temperature and precipitation, as the additional cooling benefit tends to be larger in warmer and wetter cities at the same TCP level. The positive response of urban trees' cooling efficiency to rising urban temperature is explained mainly by the stronger evapotranspiration of urban trees on hotter days.These results have important implications for alleviating urban heat risk by utilizing urban trees, particularly considering that extreme hot days are becoming more frequent in cities under global warming.

Differences in Precipitation and Related Wind Dynamics and Moisture and Heat Features in Separate Areas of the South China Sea before and after Summer Monsoon Onset

Using surface and balloon-sounding measurements, satellite retrievals, and ERA5 reanalysis during 2011–20, this study compares the precipitation and related wind dynamics, moisture and heat features in different areas of the South China Sea(SCS) before and after SCS summer monsoon onset(SCSSMO). The rainy sea around Dongsha(hereafter simply referred to as Dongsha) near the north coast, and the rainless sea around Xisha(hereafter simply referred to as Xisha) in the western SCS, are selected as two typical research subregions. It is found that Dongsha, rather than Xisha, has an earlier and greater increase in precipitation after SCSSMO under the combined effect of strong low-level southwesterly winds, coastal terrain blocking and lifting, and northern cold air. When the 950-h Pa southwesterly winds enhance and advance northward, accompanied by strengthened moisture flux, there is a strong convergence of wind and moisture in Dongsha due to a sudden deceleration and rear-end collision of wind by coastal terrain blocking. Moist and warm advection over Dongsha enhances early and deepens up to 200 h Pa in association with the strengthened upward motion after SCSSMO, thereby providing ample moisture and heat to form strong precipitation. However, when the 950-h Pa southwesterly winds weaken and retreat southward, Xisha is located in a wind-break area where strong convergence and upward motion centers move in. The vertical moistening and heating by advection in Xisha enhance later and appear far weaker compared to that in Dongsha, consistent with later and weaker precipitation.

Betaine addition to the diet alleviates intestinal injury in growing rabbits during the summer heat through the AAT/mTOR pathway

Background The aim of this experiment was to investigate the effect of different levels of betaine(Bet)inclusion in the diet on the intestinal health of growing rabbits under summer heat.A total of 100 weaned Qixing meat rabbits aged 35 d with body weight of 748.61±38.59 g were randomly divided into 5 treatment groups:control group(basal diet)and Bet groups(basal diet+0.75,1.0,1.5 or 2.0 g/kg Bet).The average daily temperature in the rabbitry during the experiment was 30.48°C and the relative humidity was 69.44%.Results Dietary addition of Bet had no significant effect on growth performance and health status of growing rabbits(P>0.05),but it increased ileal secretory immunoglobulin A content compared to the control under summer heat(P<0.05).Addition of 0.75 g/kg Bet up-regulated jejunal IL-4,down-regulated ileal TNF-αexpression(P<0.05).The addition of 1.0 g/kg Bet increased the villi height(VH)in the jejunum(P<0.05).Serum glucose levels were reduced,and the expression of SLC6A20 was up-regulated in jejunum and ileum of rabbits fed with 1.5 g/kg Bet(P<0.05).When added at 2.0 g/kg,Bet reduced serum HSP70 content,increased jejunal VH,and up-regulated duodenal SLC7A6,SLC38A2,mTOR and 4EBP-2 expression(P<0.05).Correlation analysis revealed that intestinal mTOR expression was significantly and positively correlated with SLC7A6,SLC38A2,SLC36A1 and IL-4 expression(P<0.05).Conclusions Dietary addition of Bet can up-regulate the expression of anti-inflammatory factors through the AAT/mTOR pathway,improve the intestinal immune function,alleviate intestinal damage in growing rabbits caused by summer heat,and improve intestinal health.

Changes in the Boreal Summer Intraseasonal Oscillation under Global Warming in CMIP6 Models

Changes in the activities of the Boreal Summer Intraseasonal Oscillation(BSISO)at the end of 21st century under the SSP5-8.5 scenario are assessed by adopting 17 CMIP6 models and the weak-temperature-gradient assumption.Results show that the intraseasonal variations become more structured.The BSISO-related precipitation anomaly shows a larger zonal scale and propagates further northward.However,there is no broad agreement among models on the changes in the eastward and northward propagation speeds and the frequency of individual phases.In the western North Pacific(WNP),the BSISO precipitation variance is significantly increased,at 4.62%K^(−1),due to the significantly increased efficiency of vertical moisture transport per unit of BSISO apparent heating.The vertical velocity variance is significantly decreased,at−3.51%K^(−1),in the middle troposphere,due to the significantly increased mean-state static stability.Changes in the lower-level zonal wind variance are relatively complex,with a significant increase stretching from the northwestern to southeastern WNP,but the opposite in other regions.This is probably due to the combined impacts of the northeastward shift of the BSISO signals and the reduced BSISO vertical velocity variance under global warming.Changes in strong and normal BSISO events in the WNP are also compared.They show same-signed changes in precipitation and large-scale circulation anomalies but opposite changes in the vertical velocity anomalies.This is probably because the precipitation anomaly of strong(normal)events changes at a rate much larger(smaller)than that of the meanstate static stability,causing enhanced(reduced)vertical motion.

Effects of Slow-release Nitrogen Fertilizer on Yield and Nitrogen Accumulation of Summer Maize in Shajiang Black Soil Area

[Objectives] This study was conducted to verify the field application effect of slow-release nitrogen fertilizer on summer maize in Shajiang black soil area by simultaneous sowing and fertilization, and explore the application scope and nitrogen metabolism mechanism, so as to lay a foundation for fertilizer reduction and efficiency improvement. [Methods] With maize variety Beiqing 340 and sulfur-coated urea as experimental materials, five nitrogen application levels were set, namely, control (C0), slow-release nitrogen 70 kg/hm^(2) (C70), slow-release nitrogen 140 kg/hm^(2) (C140), slow-release nitrogen 210 kg/hm^(2) (C210) and slow-release nitrogen 280 kg/hm^(2) (C280). The phosphorus and potassium fertilizers were all in accordance with the unified standard. [Results] With the application rate of slow-release nitrogen increasing, the nitrogen accumulation in organs increased first and then decreased after tasseling stage of maize. In order to reduce the fertilizing amount and increase efficiency, 210 kg/hm^(2) of slow-release nitrogen fertilizer was the best fertilizing amount for summer maize in Shajiang black soil area. [Conclusions] This study provides reference for fertilizer reduction, efficiency improvement and sustainable development of summer maize in Shajiang black soil area.

Effects of Slow-release Nitrogen on Dry Matter Accumulation,Translocation and Yield of Summer Maize

[Objectives]This study was conducted to investigate the effects of slow-release nitrogen fertilizer on dry matter accumulation and translocation of summer maize.[Methods]With Zhoudan 9 as the test variety,six different treatment were set up:blank control(CK1),slow-release urea 75 kg/hm^(2)(C1),slow-release urea 150 kg/hm^(2)(C2),slow-release urea 225 kg/hm^(2)(C3),slow-release urea 300 kg/hm^(2)(C4)and ordinary urea 300 kg/hm^(2)(CK2),to study the change law of dry matter accumulation and translocation in summer maize.[Results]Treatment slow-release urea 225 kg/hm^(2)(C4)showed summer maize yield,dry matter translocation between organs,grain contribution rate and proportion of grain dry matter in the full ripe stage higher than other treatments.Considering the weight loss and cost factors,slow-release urea 225 kg/hm^(2)(C3)could be recommended as the fertilizing amount for summer maize.[Conclusions]This study provides theoretical reference for rational selection of fertilizers for reducing fertilizer application and increasing fertilizer efficiency,and for production of summer maize in Shajiang black soil region.

Analysis of Changing Trend of Summer Precipitation in North China

Based on the reanalysis data of the National Center for Environmental Prediction(NCEP)and the precipitation dataset of the U.S.Climate Prediction Center(CPC),the changing trend of summer precipitation in North China(35°-40°N,110°-125°E)during 1979-2020 was studied.By calculating the monthly climatic precipitation in North China,it is found that precipitation was mainly distributed from June to August,so the trend of precipitation in North China from June to August was mainly analyzed.Firstly,the five-point moving average of regional mean precipitation in North China from June to August during 1979-2020 was conducted.It is found that the fitting curve of the five-point sliding average was basically consistent with the changing trend of regional precipitation,and it showed a certain upward trend.Secondly,the cumulative anomaly of regional average summer precipitation in North China showed a significant upward trend after 2005,which was similar to the moving average result,indicating that the precipitation in the later period increased compared with the earlier period.The changing trend of summer precipitation in North China in the past 42 years was analyzed,and the results show that precipitation showed a significant increasing trend in most areas of North China,so that regional average precipitation also tended to increase significantly.By comparing the precipitation in the past five years(2016-2020)and the last 36 years(1979-2015),it is found that the increase of summer precipitation in North China was more obvious,so the reasons for the increase in precipitation were further analyzed.Since the occurrence of precipitation requires favorable thermal dynamic conditions,the one-dimensional linear regression of water vapor content at 850 hPa and meridional wind speed was conduced,and it is found that the two variables tended to increase obviously,which was consistent with the increasing trend of precipitation.Seen from both the results of regional average and the spatial distribution of trends,the lower atmospheric water vapor content and wind speed showed a significant positive trend,which led to the increase of summer precipitation.Therefore,it can be concluded that there was a certain changing trend of summer precipitation in North China in the past 42 years,which can provide certain reference for the future forecast of summer precipitation in North China.

Multi-decadal Changes of the Impact of El Niño Events on Tibetan Plateau Summer Precipitation

Precipitation on the Tibetan Plateau(TP)has an important effect on the water supply and demand of the downstream population.Involving recent climate change,the multi-decadal variations of the impact of El Niño-Southern Oscillation(ENSO)events on regional climate were observed.In this work,the authors investigated the changes in summer precipitation over TP during 1950-2019.At the multi-decadal scale,the authors found that the inhabiting impact of El Niño events on the TP summer precipitation has strengthened since the late 1970s.The main factor contributing to this phenomenon is the significant amplification in the decadal amplitude of El Niño during 1978-2019 accompanied by a discernible escalation in the frequency of El Niño events.This phenomenon induces anomalous perturbations in sea surface temperatures(SST)within the tropical Indo-Pacific region,consequently weakening the atmospheric vapor transport from the western Pacific to the TP.Additionally,conspicuous anomalies in subsidence motion are observed longitudinally and latitudinally across the TP which significantly contributes to a curtailed supply of atmospheric moisture.These results bear profound implications for the multi-decadal prediction of the TP climate.

“Shanghai Summer”热浪滚滚

上海打造国际消费中心城市又一标志性品牌活动——首届“上海之夏”国际消费季已在烈日灼灼七月的上海铺展开来,“Shanghai Summer”的热度可谓海天云蒸、流金石。

Interdecadal changes in the western Siberian summer mean and extreme rainfall during 1982-2021

本文研究发现,西西伯利亚夏季降水在1995年后显著增加,2012年后又有所减少,极端降水日数和强度呈现一致的变化特征.伴随这两次降水的年代际增加/减少,西西伯利亚上空出现异常气旋/反气旋和水汽幅合/幅散.极端降水发生时的区域环流特征在三个时段基本一致:西西伯利亚低空出现气旋性异常,高空为西北-东南向的异常气旋-反气旋偶极子型.1995-2011年期间,极端降水日数更多,强度更强,上述异常环流型也更强.

Enhanced Seasonal Predictability of Spring Soil Moisture over the Indo-China Peninsula for Eastern China Summer Precipitation under Non-ENSO Conditions

Seasonal prediction of summer precipitation over eastern China is closely linked to the East Asian monsoon circulation,which is largely affected by the El Niño-Southern Oscillation(ENSO).In this study,results show that spring soil moisture(SM)over the Indo-China peninsula(ICP)could be a reliable seasonal predictor for eastern China summer precipitation under non-ENSO conditions.When springtime SM anomalies are present over the ICP,they trigger a structured response in summertime precipitation over most of eastern China.The resultant south-to-north,tri-polar configuration of precipitation anomalies has a tendency to yield increased(decreased)precipitation in the Yangtze River basin and decreased(increased)in South and North China with a drier(wetter)spring soil condition in the ICP.The analyses show that ENSO exerts a powerful control on the East Asian circulation system in the ENSO-decaying summer.In the case of ENSO forcing,the seasonal predictability of the ICP spring SM for eastern China summer precipitation is suppressed.However,in the absence of the influence of ENSO sea surface temperature anomalies from the preceding winter,the SM anomalies over the ICP induce abnormal local heating and a consequent geopotential height response owing to its sustained control on local temperature,which could,in turn,lead to abnormal eastern China summer precipitation by affecting the East Asian summer monsoon circulation.The present findings provide a better understanding of the complexity of summer climate predictability over eastern China,which is of potential significance for improving the livelihood of the people.

Correlation Between the Arabian Sea Surface Temperature and the Onset Period of South Asian Summer Monsoon with Trend Analysis on the Intensity

The long-term trend of the Arabian Sea surface temperature(ASST)during the formation of the South Asian summer monsoon(SASM)is discussed in this manuscript.From April to June,ASST changed from a meridional gradual distribution to a spatially uniform distribution and then to a zonal gradual distribution.The South Asian summer monsoon intensity(SASMI)and South Asian summer monsoon direction(SASMD)indicate that the variation of the ASST is highly related to the formation of the SASM during the summer monsoon period and can contribute to the spread of the SASM from the Southwest Arabian Sea throughout all of South Asia.Results of the correlation between the ASST and SASMI for the same month and its adjacent months were the same,and the areas of the positive correlation between the ASST and SASMI significantly increased from May–June as compared to April–May.The maximum correlation coefficient was 0.86.The results of the ASST and SASMD for the same month and its adjacent months were substantially different.However,the ASST and SASMD for May and April also showed a high positive correlation with a maximum correlation coefficient of 0.61 in the southwestern Arabian Sea.Existence of the ASST had a spatially consistent and significant upward trend with a mean increase of 0.6℃during the summer monsoon period from 1980 to 2020(between April and September),whereas the SASMI had a strengthening trend along the western and southwestern regions of the Arabian Sea and the southeastern region of the Arabian Peninsula.Meanwhile,the rest of the study regions showed a declining trend.Overall,the entire study region showed a slight downward trend,and the average value decreased by 0.02ms^(−1).

Contrasting Regional Responses of Indian Summer Monsoon Rainfall to Exhausted Spring and Concurrently Emerging Summer El Nino Events

The inverse relationship between the warm phase of the El Nino Southern Oscillation(ENSO)and the Indian Summer Monsoon Rainfall(ISMR)is well established.Yet,some El Nino events that occur in the early months of the year(boreal spring)transform into a neutral phase before the start of summer,whereas others begin in the boreal summer and persist in a positive phase throughout the summer monsoon season.This study investigates the distinct influences of an exhausted spring El Nino(springtime)and emerging summer El Nino(summertime)on the regional variability of ISMR.The two ENSO categories were formulated based on the time of occurrence of positive SST anomalies over the Nino-3.4 region in the Pacific.The ISMR’s dynamical and thermodynamical responses to such events were investigated using standard metrics such as the Walker and Hadley circulations,vertically integrated moisture flux convergence(VIMFC),wind shear,and upper atmospheric circulation.The monsoon circulation features are remarkably different in response to the exhausted spring El Nino and emerging summer El Nino phases,which distinctly dictate regional rainfall variability.The dynamic and thermodynamic responses reveal that exhausted spring El Nino events favor excess monsoon rainfall over eastern peninsular India and deficit rainfall over the core monsoon regions of central India.In contrast,emerging summer El Nino events negatively impact the seasonal rainfall over the country,except for a few regions along the west coast and northeast India.

Study on the Sediment Transport Flux and Mechanism in the Bohai Strait at the Tidal and Monthly Scales in Summer

Based on the data of tidal currents and suspended sediment concentrations observed synchronously at 11 stations in the Bohai Strait lasting for 25 hours,the temporal and spatial variations of currents and suspended sediment concentrations in the Bohai Strait in summer were analyzed.The Study preliminarily discussed the transport mechanism,transport trend and transport flux of suspended sediments in summer,using flux-mechanism decomposition method and numerical simulation.The suspended sediment transport was mainly controlled by advection and next influenced by vertical net circulation,while resuspension is relatively weak in Bohai Strait.The single-width fluxes of investigation stations varied from 3.8 to 89.1 gm^(−1) s^(−1),with the maximum value in Miaodao Strait.The suspended sediment transport trends in Laotieshan channel along the vertical section are obviously distinct.The waters mainly flow out of the Bohai Sea in surface layer,while into the Bohai Sea in bottom layer.However,the transport trends of other channels in the centre and south are consistent vertically.The sediments in the Bohai Strait follows the transport pattern of moving outward from the south and inward from the north in summer,i.e.,the sediments are carried out of the Bohai Sea through the Laotieshan channel,while into the Bohai Sea through other channels.And the outflow flux exceeds the inflow flux in August with the net water flux of 1.4×10^(10)m^(3),basically same as the deliveries of the rivers into the Bohai Sea.Moreover,the suspended sediment flux is 0.33 Mt under the action of tidal residual currents in the Yellow Sea in August.

Combined effects of high temperature and waterlogging on yield and stem development of summer maize

The purpose of this study was to identify the physiological mechanism underlying the effects of high temperature and waterlogging on summer maize.The stem development and yield of the maize hybrid Denghai 605 in response to high-temperature stress,waterlogging stress,and their combination applied for six days at the third-leaf,sixth-leaf,and tasseling stages were recorded.The combined stresses reduced lignin biosynthetic enzyme activity and lignin accumulation,leading to abnormal stem development.Reduction of the area and number of vascular bundles in stems led to reduced dry matter accumulation and allocation.Decreased grain dry weight at all three stages reduced grain yield relative to a control.In summary,high temperature,waterlogging,and their combined stress impaired stem development and grain yield of summer maize.The combined stresses were more damaging than either stress alone.

Interannual Meridional Displacement of the Upper-Tropospheric Westerly Jet over Western East Asia in Summer

The interannual meridional displacement of the upper-tropospheric westerly jet over the eastern portion of East Asia in summer has been well documented.This study,however,investigates the interannual meridional displacement of the westerly jet over the western portion of East Asia in summer,which is distinct from its eastern counterpart.The results show that the meridional displacement of the western East Asian jet shows a clear asymmetric feature;that is,there are remarkable differences between the southward and northward displacement of the jet.The southward displacement of the jet corresponds to suppressed convection in the tropical western North Pacific and Maritime Continent and enhanced convection in the equatorial Pacific,which can be explained by the warmer sea surfaces found in the northern Indian Ocean and equatorial eastern Pacific.These tropical anomalies somewhat resemble those associated with the eastern East Asian jet variability.However,the northward displacement of the western East Asian jet does not correspond to significant convection and SST anomalies in the entire tropics;instead,the northward displacement of the jet corresponds well to the positive phase of the Arctic Oscillation.Furthermore,the meridional displacement of the western jet has asymmetric impacts on rainfall and surface air temperatures in East Asia.When the western jet shifts northward,more precipitation is found over South China and Northeast China,and higher temperatures appear in northern China.By contrast,when the jet shifts southward,more precipitation appears over the East Asian rainy belt,including the Yangtze River valley,South Korea,and southern and central Japan and warmer temperatures are found South and Southeast Asia.

Skilful Forecasts of Summer Rainfall in the Yangtze River Basin from November

Variability in the East Asian summer monsoon(EASM)brings the risk of heavy flooding or drought to the Yangtze River basin,with potentially devastating impacts.Early forecasts of the likelihood of enhanced or reduced monsoon rainfall can enable better management of water and hydropower resources by decision-makers,supporting livelihoods and major economic and population centres across eastern China.This paper demonstrates that the EASM is predictable in a dynamical forecast model from the preceding November,and that this allows skilful forecasts of summer mean rainfall in the Yangtze River basin at a lead time of six months.The skill for May–June–July rainfall is of a similar magnitude to seasonal forecasts initialised in spring,although the skill in June–July–August is much weaker and not consistently significant.However,there is some evidence for enhanced skill following El Niño events.The potential for decadal-scale variability in forecast skill is also examined,although we find no evidence for significant variation.

Monsoon Break over the South China Sea during Summer: Statistical Features and Associated Atmospheric Anomalies

This study identifies break events of the South China Sea(SCS)summer monsoon(SCSSM)based on 42 years of data from 1979 to 2020,and investigates their statistical characteristics and associated atmospheric anomalies.A total of 214 break events are identified by examining the convection evolution during each monsoon season.It is found that most events occur between June and September and show a roughly even distribution.Short-lived events(3–7 days)are more frequent,accounting for about two thirds of total events,with the residual one third for long-lived events(8–24 days).The SCSSM break is featured by drastic variations in various atmospheric variables.Particularly,the convection and precipitation change from anomalous enhancement in adjoining periods to a substantial suppression during the break,with the differences being more than 60 W m−2 for outgoing longwave radiation(OLR)and 10 mm d−1 for precipitation.This convection/precipitation suppression is accompanied by an anomalous anticyclone in the lower troposphere,corresponding to a remarkable westward retreat of the monsoon trough from the Philippine Sea to the Indochina Peninsula,which reduces the transportation of water vapor into the SCS.Besides,the pseudo-equivalent potential temperature()declines sharply,mainly attributable to the local specific humidity reduction caused by downward dry advection.Furthermore,it is found that the suppressed convection and anomalous anticyclone responsible for the monsoon break form near the equatorial western Pacific and then propagate northwestward to the SCS.