scholarly journals Atmospheric Controls on Seasonal and Interannual Variations in the Precipitation Isotope in the East Asian Monsoon Region

2016 ◽  
Vol 29 (4) ◽  
pp. 1339-1352 ◽  
Author(s):  
Zhongyin Cai ◽  
Lide Tian
Keyword(s):  
Atmospheric Circulation ◽  
Asian Monsoon ◽  
East Asian Monsoon ◽  
East Asian ◽  
Walker Circulation ◽  
Condensation Temperature ◽  
Interannual Variations ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
Precipitation Δ18o

ABSTRACT Understanding variations in isotopic composition of precipitation from monsoon regions is crucial for its utilization in paleoclimate studies. This study explores the relationship between precipitation δ18O data for the East Asian monsoon (EAM) region archived in Global Network for Isotopes in Precipitation (GNIP) and the cloud data archived in ISCCP and their linkage with large-scale atmospheric circulation patterns. Results show that precipitation δ18O are significantly and positively correlated with cloud-top pressure (CTP) on both local and regional scales. Mechanically speaking, the stronger the monsoon convection precipitation, the higher the cloud and the lower the condensation temperature and thus the lower the precipitation δ18O. This result implies that the sharp drop in precipitation δ18O in the early summer in monsoonal Asia is related to the atmospheric circulation pattern rather than the different moisture sources, as was previously assumed. This result helps explain the processes leading to the observed “amount effect.” A comparison of atmospheric circulation patterns with precipitation δ18O on an interannual scale shows that the positive CTP anomalies in the central Indo-Pacific within the weak Walker circulation (El Niño) can be associated with positive δ18O anomalies, while negative CTP anomalies in the central Indo-Pacific within the strong Walker circulation (La Niña) can be linked to negative δ18O anomalies. This result further confirms the aforementioned conclusion. This is important for understanding paleoclimatic change in monsoonal Asia, as interannual variations in stable isotopes in that region have received less attention in the past.

scholarly journals Effect of the El Niño Decaying Pace on the East Asian Summer Monsoon Circulation Pattern during Post-El Niño Summers

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 140
Author(s):  
Wenping Jiang ◽  
Gen Li ◽  
Gongjie Wang
Keyword(s):  
El Niño ◽  
Asian Monsoon ◽  
East Asian Monsoon ◽  
El Nino ◽  
East Asian ◽  
Circulation Pattern ◽  
Northwest Pacific ◽  
Monsoon Circulation ◽  
Circulation Patterns ◽  
Sst Anomalies

El Niño events vary from case to case with different decaying paces. In this study, we demonstrate that the different El Niño decaying paces have distinct impacts on the East Asian monsoon circulation pattern during post-El Niño summers. For fast decaying (FD) El Niño summers, a large-scale anomalous anticyclone dominates over East Asia and the North Pacific from subtropical to mid-latitude; whereas, the East Asian monsoon circulation display a dipole pattern with anomalous northern cyclone and southern anticyclone for slow decaying (SD) El Niño summers. The difference in anomalous East Asian monsoon circulation patterns was closely associated with the sea surface temperature (SST) anomaly patterns in the tropics. In FD El Niño summers, the cold SST anomalies in the tropical central-eastern Pacific and warm SST anomalies in the Maritime Continent induce the anticyclone anomalies over the Northwest Pacific. In contrast, the warm Kelvin wave anchored over the tropical Indian Ocean during SD El Niño summers plays a crucial role in sustaining the anticyclone anomalies over the Northwest Pacific. In particular, the opposite atmospheric circulation anomaly patterns over Northeast Asia and the mid-latitude North Pacific are mainly modulated by the stationary Rossby wave trains triggered by the opposite SST anomalies in the tropical eastern Pacific during FD and SD El Niño summers. Finally, the effect of distinct summer monsoon circulation patterns associated with the El Niño decay pace on the summer climate over East Asia are also discussed.

Chinese loess and the evolution of the east Asian monsoon

2000 ◽  
Vol 24 (1) ◽  
pp. 75-96 ◽  
Author(s):  
Chun Chang Huang ◽  
Jiangli Pang ◽  
Jingpo Zhao
Keyword(s):  
Climatic Change ◽  
Atmospheric Circulation ◽  
Asian Monsoon ◽  
East Asian Monsoon ◽  
East Asian ◽  
The Tibetan Plateau ◽  
Glacial Cycle ◽  
Last Interglacial ◽  
Chinese Loess ◽  
Climatic Variations

The history of the east Asian monsoon has been reconstructed from proxy records from the aeolian loess-palaeosol sequence in the Loess Plateau. It has been suggested that the monsoonal atmospheric circulation was initiated abruptly at 2.6 M yr BP. From about 1.2 M yrBP, the climate was characterized by contrasts between dry-cold periods brought on by the northwesterly monsoon and humid-warm periods brought about by the southeasterly monsoon. The periodic changes related to the earth’s orbital cycles have been clearly identified. Since about 0.6 M yr BP, the monsoonal climatic variations have become extremely pronounced and these correlate well with the marine isotope stages. The three-step shift in the east Asian monsoon towards greater variation seems to have been caused by the accelerated uplifting of the Tibetan Plateau. Climatic change during the last interglacial-glacial cycle recorded in the loess seems to match the SPECMAP δ18O record exactly. Six episodes of extremely strong dustfall events (brought on by the strengthened northwesterly monsoon winds) have been identified during the last glaciation. The ages of these episodes seem to match the Heinrich events in the North Atlantic and the Dansgaard-Oeschger events in Greenland. It is therefore suggested that the atmospheric circulation in east Asia is very sensitive to climatic change in high latitudes and has been responsive to global climatic change over the last 2.6 M yr. Millennial-scale climatic variations have also been identified in the Holocene loess. The article concludes by suggesting areas of research that might be undertaken in order to improve our understanding of the Chinese loess and of the evolution of the east Asian monsoon.

Hail Day Frequency Trends and Associated Atmospheric Circulation Patterns over China during 1960–2012

2016 ◽  
Vol 29 (19) ◽  
pp. 7027-7044 ◽  
Author(s):  
Mingxin Li ◽  
Qinghong Zhang ◽  
Fuqing Zhang
Keyword(s):  
Tibetan Plateau ◽  
Atmospheric Circulation ◽  
Southern China ◽  
East Asian ◽  
Northern China ◽  
The Tibetan Plateau ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
Change In Mean

Abstract Based on a comprehensive collection of hail observations and the NCEP–NCAR reanalyses from 1960 to 2012, the long-term trends of hail day frequency in mainland China and the associated changes in atmospheric circulation patterns were analyzed. There was no detectable trend in hail frequency from 1960 to the early 1980s, but a significant decreasing trend was apparent in later periods throughout most of China and in particular over the Tibetan Plateau from the early 1980s and over northern and northwestern China from the early 1990s. Hail frequency in southern China did not decrease as significantly as in other regions over the last couple of decades. An objective classification method, the obliquely rotated T-mode principal component technique, was used to investigate atmospheric circulation patterns. It was found that 51.85% of the hail days occurred during two major circulation types, both of which were associated with cold frontal systems in northern China. More specifically, the synoptic trough in East Asia, signified by the meridional circulation at 850 hPa, became considerably weaker after 1990. This change in the synoptic pattern is consistent with a weakening trend in the East Asian summer monsoon, the primary dynamic forcing of moisture transport that contributes to the generation of severe convection in northern China. The long-term variability of hail day frequency over the Tibetan Plateau was more strongly correlated with the change in mean freezing-level height (FLH) than the strength of the East Asian monsoon.

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