东亚夏季环流多齿轮耦合特征及其对中国夏季降水异常的影响分析     

庞轶舒  祝从文  马振峰  秦宁生 《大气科学》2019,43(4):875-894

东亚夏季风成员的相互作用,构成了东亚夏季风高、低层环流的“多齿轮耦合”形态。本文利用多变量主成分分析（MV-EOF）等方法诊断分析了东亚夏季风多齿轮耦合的变化特征、耦合机制、时间稳定性、空间稳定特征及其对中国夏季降水的影响机制,并在此基础上构建了典型多齿轮耦合形态影响夏季降水的概念模型。结果表明,多齿轮耦合受到垂直温、压场的强迫和青藏高原大地形的影响,主要表现在年际变化上（周期为2～6年）。其前两个模态稳定地反映了东亚夏季风成员典型联动作用。在第一模态中,北方气旋、南亚高压和西太平洋副热带高压为主要耦合系统。其中北方气旋为正压结构,在高层通过南侧偏西气流与南亚高压耦合,南亚高压则通过中纬东部地区下沉辐散气流与西太平洋副热带高压联动。当该耦合模态增强时,有利于中国夏季降水呈自北向南“＋－＋－”分布。第二模态主要反映中高纬气旋、东亚副热带西风气流、南亚高压、西北太平洋反气旋系统和西太平洋副热带高压耦合特征。其中,中高纬气旋和西北太平洋反气旋为正压系统,两者通过其间的东南气流联动。气旋系统在高层通过南侧西风与东亚副热带西风急流和南亚高压联动。反气旋在中低层通过南侧的偏东气流影响副热带高压强度和面积。当该耦合模态增强时,中国黄河以北及河套地区降水偏多,黄河以南降水偏少。  相似文献   

Seesaw Pattern of Rainfall Anomalies between the Tropical Western North Pacific and Central Southern China during Late Summer     

Xinyu LI  Riyu LU 《大气科学进展》2019,36(3):261-270

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.  相似文献   

Holocene initiation and expansion of the southern margins of northern peatlands triggered by the East Asian summer monsoon recession     

《地学前缘(英文版)》2023,14(2):101526

Northern peatlands represent one of the largest biospheric carbon reservoirs in the world. Their southern margins act as new carbon reservoirs, which can greatly influence the global carbon dynamics. However, the Holocene initiation, expansion and climate sensitivity of these peatlands remain intensely debated. Here we used a compilation of basal peat ages across six isolated peatlands at the southern margins of northern peatlands to address these issues. We found that the earliest initiation event of these peatlands occurred after the Younger Dryas (YD, 12,800–11,700 years ago) period. The second initiation event and rapid expansion occurred since 5 ka cal. BP. The recession of East Asian summer monsoon (EASM) during the YD period and at around 5 ka cal. BP likely played a major role in controlling the initiation and expansion of these peatlands. The rapid expansion of these peatlands possibly contributed to the significant increases in atmospheric methane concentrations during the late Holocene because of the minerotrophic fens status and rapid expansion of them. These ecological processes are different from northern peatlands, indicating the special carbon sink and source implications of these peatlands in the global carbon cycle.  相似文献   

印尼贯穿流源区马鲁古海与哈马黑拉海水团来源的季节和年际变化   总被引：2，自引：1，他引：1  

王露  周磊  谢玲玲  郑全安  李强  李明明 《海洋学报(英文版)》2019,38(4):58-71

So far, large uncertainties of the Indonesian throughflow(ITF) reside in the eastern Indonesian seas, such as the Maluku Sea and the Halmahera Sea. In this study, the water sources of the Maluku Sea and the Halmahera Sea are diagnosed at seasonal and interannual timescales and at different vertical layers, using the state-of-the-art simulations of the Ocean General Circulation Model(OGCM) for Earth Simulator(OFES). Asian monsoon leaves clear seasonal footprints on the eastern Indonesian seas. Consequently, the subsurface waters(around 24.5σ_θ and at ～150 m) in both the Maluku Sea and the Halmahera Sea stem from the South Pacific(SP) during winter monsoon, but during summer monsoon the Maluku Sea is from the North Pacific(NP), and the Halmahera Sea is a mixture of waters originating from the NP and the SP. The monsoon impact decreases with depth, so that in the Maluku Sea, the intermediate water(around 26.8σ_θ and at ～480 m) is always from the northern Banda Sea and the Halmahera Sea water is mainly from the SP in winter and the Banda Sea in summer. The deep waters(around27.2σ_θ and at ～1 040 m) in both seas are from the SP, with weak seasonal variability. At the interannual timescale,the subsurface water in the Maluku Sea originates from the NP/SP during El Ni?o/La Ni?a, while the subsurface water in the Halmahera Sea always originates from the SP. Similar to the seasonal variability, the intermediate water in Maluku Sea mainly comes from the Banda Sea and the Halmahera Sea always originates from the SP. The deep waters in both seas are from the SP. Our findings are helpful for drawing a comprehensive picture of the water properties in the Indonesian seas and will contribute to a better understanding of the ocean-atmosphere interaction over the maritime continent.  相似文献   

1961—1987年与1988—2014年辽宁省气候区划界线变化及可能气候成因     

王涛  王乙舒  崔妍  敖雪  侯依玲  沈玉敏  王小桃 《地理研究》2019,38(4):794-806

基于同一区划方法、指标体系,使用1961—2014年辽宁省52站气象观测资料,分析辽宁省气温、气候区划指标、范围及界线的变动特征。结果表明：辽宁省年均气温在1988年发生一次突变,突变后气温开始显著上升;≥10 ℃积温日数比较显著地响应气温突变,而干燥指数、7月平均气温变化不显著。在空间分布上区划指标值均存在不同程度的变化。① 全省≥10 ℃积温日数均出现增加,但在中西部地区显著增加;② 在盘锦-抚顺一线以北（南）,气候总体呈不显著变湿（干）趋势;③ 7月平均气温呈缓慢上升趋势。区划范围及界线位置出现更加显著地变化：① 暖温带范围主要向北向东扩展,中温带向东收缩;② 半湿润区范围主要向北向西扩展,半干旱区向西北方向收缩,湿润区范围基本不变;③ Tb范围显著向北向东扩展,Ta范围向北向东收缩。在此基础上分析了气候格局变化的可能气候成因,发现突变后≥10 ℃积温日数期间500 hPa高度场增加与4月和10月东亚冬季风减弱,4—10月东北冷涡持续天数增加和7月500 hPa高度场增加,可能分别是温度带,Tb区、Ta区和半湿润区、半干旱区变化的原因。  相似文献   

Climate over mainland Southeast Asia 10.5–5 ka          下载免费PDF全文

AKKANEEWUT CHABANGBORN  BARBARA WOHLFARTH 《第四纪科学杂志》2014,29(5):445-454

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A high‐resolution monsoon record of millennial‐scale oscillations during Late MIS 3 from Wulu Cave,south‐west China          下载免费PDF全文

FUCAI DUAN  DIANBING LIU  HAI CHENG  XIANFENG WANG  YONGJIN WANG  XINGGONG KONG  SHITAO CHEN 《第四纪科学杂志》2014,29(1):83-90

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Trend and extreme occurrence of precipitation in a mid‐latitude Eurasian steppe watershed at various time scales          下载免费PDF全文

Xixi Wang  Xiaomin Yang  Tingxi Liu  Fengling Li  Ruizhong Gao  Limin Duan  Yanyun Luo 《水文研究》2014,28(22):5547-5560

The confounding effects of step change invalidate the stationarity assumption of commonly used trend analysis methods such as the Mann–Kendall test technique, so previous studies have failed to explain inconsistencies between detected trends and observed large precipitation anomalies. The objectives of this study were to (1) formulate a trend analysis approach that considers nonstationarity due to step changes, (2) use this approach to detect trends and extreme occurrences of precipitation in a mid‐latitude Eurasian steppe watershed in North China, and (3) examine how runoff responds to precipitation trends in the study watershed. Our results indicate that annual precipitation underwent a marginal step jump around 1995. The significant annual downward trend after 1994 was primarily due to a decrease in summer rainfall; other seasons exhibited no significant precipitation trends. At a monthly scale, July rainfall after 1994 exhibited a significant downward trend, whereas precipitation in other months had no trend. The percentage of wet days also underwent a step jump around 1994 following a significant decreasing trend, although the precipitation intensity exhibited neither a step change nor any significant trend. However, both low‐frequency and high‐frequency precipitation events in the study watershed occurred more often after than before 1994; probably as either a result or an indicator of climate change. In response to these precipitation changes, the study watershed had distinctly different precipitation‐runoff relationships for observed annual precipitations of less than 300 mm, between 300 and 400 mm, and greater than 400 mm. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

最近11万年来东亚季风轨道与千年尺度气候变率在南京下蜀黄土中的记录     

张茂恒  孟景闻  夏应菲  赖忠平  汪永进 《地层学杂志》2011,(3):321-327

对南京李家岗下蜀黄土剖面上部的近20 m地层进行野外观察和室内研究,划分出5层黄土和5层古土壤,按5 cm间距采集了Rb/Sr、色度、磁化率和粒度样品,并在剖面和可追索的相邻剖面上采集了13个光释光测年样品。分析结果显示,Rb/Sr、色度和磁化率等夏季风代用指标曲线所表现的4次岁差变率振荡具有高度的一致性,依据气候地层...  相似文献   

中东亚中全新世气候与植被反馈作用:PMIP 2多模式结果分析          下载免费PDF全文

王志远  靳立亚  俞飞  张肖剑  姜大膀 《第四纪研究》2011,31(1):36-47

文章选取了参加国际古气候模拟比较计划(Paleoclimate Modeling Intercomparison Project,简称PMIP)的6个耦合气候模式的模拟结果,着重对中全新世中东亚干旱区以及东亚季风区的夏季气候变化(气温、降水)进行分析,探讨了植被反馈作用对这3个区域中全新世气候变化的影响.由于各个模式之...  相似文献