本文基于一个国际通用的耦合器OASIS,将区域大气模式CREM(Climate version of Regional Eta Model)和RegCM3(Regional Climate Model version 3)分别与改进的普林斯顿区域海洋模式(POM2000)耦合,建立了一个区域海气耦合模式,并利用该耦...本文基于一个国际通用的耦合器OASIS,将区域大气模式CREM(Climate version of Regional Eta Model)和RegCM3(Regional Climate Model version 3)分别与改进的普林斯顿区域海洋模式(POM2000)耦合,建立了一个区域海气耦合模式,并利用该耦合模式讨论了不同大气分量对耦合模式性能的影响.以1998年西北太平洋夏季风为模拟个例,结果表明,对降水而言,CREM和RegCM3耦合前后显示出显著不同的特征.较之控制试验(即不考虑海气耦合),耦合后CREM(RegCM3)模拟的海上降水显著增多(减少).上述降水变化与耦合模拟的海温场偏差不同有关:CREM(RegCM3)耦合后海温偏暖(偏冷),增加(减少)了海表蒸发,增加(减少)了海上降水.分析表明,控制试验中模式对海洋区域温湿垂直廓线的模拟偏差是导致耦合海温偏差的重要原因.CREM(RegCM3)模拟的低层大气偏暖偏湿(干冷),使得海表潜热偏少(多),低层大气层结较之观测更不稳定(稳定),导致低层云量偏少(多),到达海表的净短波辐射偏多(少).CREM(RegCM3)在观测海温强迫下对海表净热通量模拟偏少(多),相当于一个潜在的虚假热源(冷源).一旦开始海气耦合,该热源(冷源)会使模拟的SST升温(降温),产生暖(冷)偏差.温湿廓线的模拟偏差可能与两个大气模式对对流降水过程的描述不同有关.展开更多
用奇异值分解(Singular Value Decomposition,SVD)方法,给出了四季年代际和年际时间尺度上北大西洋和北太平洋海表温度(Sea Surface Temperature,SST)的显著遥相关。用SVD主模态时间系数构造了海温异常指数I,分析了它们与同期亚太夏季...用奇异值分解(Singular Value Decomposition,SVD)方法,给出了四季年代际和年际时间尺度上北大西洋和北太平洋海表温度(Sea Surface Temperature,SST)的显著遥相关。用SVD主模态时间系数构造了海温异常指数I,分析了它们与同期亚太夏季风和我国东部夏季降水异常的关系。结果表明:两大洋间的SST遥联在年际、年代际时间尺度上都与亚太夏季风相关,其中,年际尺度的两大洋SST遥联与长江流域的降水存在显著相关。展开更多
研究晚全新世季风气候演变有助于进一步认识与预测未来季风区气候变化。太平洋东西两岸是全球季风集中分布的地区,已经有大量的古气候记录发表,但是缺乏对各个季风区气候突变事件以及整体变化趋势的对比研究。针对这一问题,选取亚洲季...研究晚全新世季风气候演变有助于进一步认识与预测未来季风区气候变化。太平洋东西两岸是全球季风集中分布的地区,已经有大量的古气候记录发表,但是缺乏对各个季风区气候突变事件以及整体变化趋势的对比研究。针对这一问题,选取亚洲季风区、印澳季风区、北美季风区、南美季风区11个洞穴石笋δ18O和1个湖泊Ti含量,对比研究各个记录在3.5~0.5 ka B.P.期间指示的夏季风变化特征。通过对比发现四大季风区的石笋δ18O在晚全新世整体上呈现偏正趋势,指示夏季风减弱;2次重要的气候突变事件1.5 ka B.P.和2.7 ka B.P.弱夏季风事件在各个季风区内均有表现;同时也记录了一系列十年际-百年际尺度的弱夏季风事件,表明太平洋东西两岸和南北半球的夏季风都有减弱的趋势,这与先前研究认为的南北半球呈现"see-saw"模式表现出不一样的特征。晚全新世以来ENSO(El Nino-Southern Oscillation)活动的增强对太平洋东西两岸南北半球夏季风减弱具有重要影响。在El Nino事件发生时,Walker环流减弱,而且它的上升支向东移动远离西太平洋暖池,西太平洋副热带高压增强并向西移动,导致亚洲夏季风减弱。Walker环流的东移也会使得印度尼西亚-太平洋暖池(Indo-Pacific Warm Pool,简称IPWP)海温下降,热带季节内震荡减弱致使印澳夏季风减弱;此外,El Nino事件发生时,赤道东太平洋海水温度上升导致东西太平洋海水温度梯度减弱,在此状态下南美季风区低空急流(Low Level Jet,简称LLJ)减弱,导致南美夏季风减弱;同时,北美洲加勒比海低空急流增强,使得该季风区下沉气流增强,导致北美夏季风减弱。我们的研究表明,在晚全新世ENSO活动增强的状态下,太平洋东西两岸南北半球夏季风变化可能都呈现减弱趋势。展开更多
Using NCEP/NCAR reanalysis data and monthly precipitation over 160 conventional stations in China, analyses of moisture transport characteristics and corresponding precipitation variation in the east part of China in ...Using NCEP/NCAR reanalysis data and monthly precipitation over 160 conventional stations in China, analyses of moisture transport characteristics and corresponding precipitation variation in the east part of China in summer are made, and studies are carried out on possible influence on moisture transport and precipitation in summer by the variation of Antarctic Oscillation (AAO). The results show that the abnormal variation of the AAO affected the summer precipitation in China significantly. The variation of AAO can cause the variation of intension and location of Northwestern Pacific High, which in turn cause the variation of summer monsoon rainfall in the eastern China.展开更多
It is well known that suppressed convection in the tropical western North Pacific(WNP) induces an anticyclonic anomaly,and this anticyclonic anomaly results in more rainfall along the East Asian rain band through more...It is well known that suppressed convection in the tropical western North Pacific(WNP) induces an anticyclonic anomaly,and this anticyclonic anomaly results in more rainfall along the East Asian rain band through more water vapor transport during summer, as well as early and middle summer. However, the present results indicate that during late summer(from mid-August to the beginning of September), the anomalous anticyclone leads to more rainfall over central southern China(CSC), a region quite different from preceding periods. The uniqueness of late summer is found to be related to the dramatic change in climatological monsoon flows: southerlies over southern China during early and middle summer but easterlies during late summer. Therefore, the anomalous anticyclone, which shows a southerly anomaly over southern China, enhances monsoonal southerlies and induces more rainfall along the rain band during early and middle summer. During late summer,however, the anomalous anticyclone reflects a complicated change in monsoon flows: it changes the path, rather than the intensity, of monsoon flows. Specifically, during late summers of suppressed convection in the tropical WNP, southerlies dominate from the South China Sea to southern China, and during late summers of enhanced convection, northeasterlies dominate from the East China Sea to southern China, causing more and less rainfall in CSC, respectively.展开更多
文摘本文基于一个国际通用的耦合器OASIS,将区域大气模式CREM(Climate version of Regional Eta Model)和RegCM3(Regional Climate Model version 3)分别与改进的普林斯顿区域海洋模式(POM2000)耦合,建立了一个区域海气耦合模式,并利用该耦合模式讨论了不同大气分量对耦合模式性能的影响.以1998年西北太平洋夏季风为模拟个例,结果表明,对降水而言,CREM和RegCM3耦合前后显示出显著不同的特征.较之控制试验(即不考虑海气耦合),耦合后CREM(RegCM3)模拟的海上降水显著增多(减少).上述降水变化与耦合模拟的海温场偏差不同有关:CREM(RegCM3)耦合后海温偏暖(偏冷),增加(减少)了海表蒸发,增加(减少)了海上降水.分析表明,控制试验中模式对海洋区域温湿垂直廓线的模拟偏差是导致耦合海温偏差的重要原因.CREM(RegCM3)模拟的低层大气偏暖偏湿(干冷),使得海表潜热偏少(多),低层大气层结较之观测更不稳定(稳定),导致低层云量偏少(多),到达海表的净短波辐射偏多(少).CREM(RegCM3)在观测海温强迫下对海表净热通量模拟偏少(多),相当于一个潜在的虚假热源(冷源).一旦开始海气耦合,该热源(冷源)会使模拟的SST升温(降温),产生暖(冷)偏差.温湿廓线的模拟偏差可能与两个大气模式对对流降水过程的描述不同有关.
文摘用奇异值分解(Singular Value Decomposition,SVD)方法,给出了四季年代际和年际时间尺度上北大西洋和北太平洋海表温度(Sea Surface Temperature,SST)的显著遥相关。用SVD主模态时间系数构造了海温异常指数I,分析了它们与同期亚太夏季风和我国东部夏季降水异常的关系。结果表明:两大洋间的SST遥联在年际、年代际时间尺度上都与亚太夏季风相关,其中,年际尺度的两大洋SST遥联与长江流域的降水存在显著相关。
基金supported by the National Natural Science Foundation of China[grant number 42275025]the Youth Innovation Promotion Association of the Chinese Academy of Sciences[grant number 2023084].
文摘研究晚全新世季风气候演变有助于进一步认识与预测未来季风区气候变化。太平洋东西两岸是全球季风集中分布的地区,已经有大量的古气候记录发表,但是缺乏对各个季风区气候突变事件以及整体变化趋势的对比研究。针对这一问题,选取亚洲季风区、印澳季风区、北美季风区、南美季风区11个洞穴石笋δ18O和1个湖泊Ti含量,对比研究各个记录在3.5~0.5 ka B.P.期间指示的夏季风变化特征。通过对比发现四大季风区的石笋δ18O在晚全新世整体上呈现偏正趋势,指示夏季风减弱;2次重要的气候突变事件1.5 ka B.P.和2.7 ka B.P.弱夏季风事件在各个季风区内均有表现;同时也记录了一系列十年际-百年际尺度的弱夏季风事件,表明太平洋东西两岸和南北半球的夏季风都有减弱的趋势,这与先前研究认为的南北半球呈现"see-saw"模式表现出不一样的特征。晚全新世以来ENSO(El Nino-Southern Oscillation)活动的增强对太平洋东西两岸南北半球夏季风减弱具有重要影响。在El Nino事件发生时,Walker环流减弱,而且它的上升支向东移动远离西太平洋暖池,西太平洋副热带高压增强并向西移动,导致亚洲夏季风减弱。Walker环流的东移也会使得印度尼西亚-太平洋暖池(Indo-Pacific Warm Pool,简称IPWP)海温下降,热带季节内震荡减弱致使印澳夏季风减弱;此外,El Nino事件发生时,赤道东太平洋海水温度上升导致东西太平洋海水温度梯度减弱,在此状态下南美季风区低空急流(Low Level Jet,简称LLJ)减弱,导致南美夏季风减弱;同时,北美洲加勒比海低空急流增强,使得该季风区下沉气流增强,导致北美夏季风减弱。我们的研究表明,在晚全新世ENSO活动增强的状态下,太平洋东西两岸南北半球夏季风变化可能都呈现减弱趋势。
基金Under the auspices of the National Natural Science Foundation of China (No. 40233037)
文摘Using NCEP/NCAR reanalysis data and monthly precipitation over 160 conventional stations in China, analyses of moisture transport characteristics and corresponding precipitation variation in the east part of China in summer are made, and studies are carried out on possible influence on moisture transport and precipitation in summer by the variation of Antarctic Oscillation (AAO). The results show that the abnormal variation of the AAO affected the summer precipitation in China significantly. The variation of AAO can cause the variation of intension and location of Northwestern Pacific High, which in turn cause the variation of summer monsoon rainfall in the eastern China.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41721004 and 41320104007)
文摘It is well known that suppressed convection in the tropical western North Pacific(WNP) induces an anticyclonic anomaly,and this anticyclonic anomaly results in more rainfall along the East Asian rain band through more water vapor transport during summer, as well as early and middle summer. However, the present results indicate that during late summer(from mid-August to the beginning of September), the anomalous anticyclone leads to more rainfall over central southern China(CSC), a region quite different from preceding periods. The uniqueness of late summer is found to be related to the dramatic change in climatological monsoon flows: southerlies over southern China during early and middle summer but easterlies during late summer. Therefore, the anomalous anticyclone, which shows a southerly anomaly over southern China, enhances monsoonal southerlies and induces more rainfall along the rain band during early and middle summer. During late summer,however, the anomalous anticyclone reflects a complicated change in monsoon flows: it changes the path, rather than the intensity, of monsoon flows. Specifically, during late summers of suppressed convection in the tropical WNP, southerlies dominate from the South China Sea to southern China, and during late summers of enhanced convection, northeasterlies dominate from the East China Sea to southern China, causing more and less rainfall in CSC, respectively.
