scholarly journals Investigating How The Indian Monsoon Impacts Climate On The Tibetan Plateau

2017 ◽  
Author(s):  
Xiaolong Zhang
2016 ◽  
Author(s):  
Xiaoping Wang ◽  
Jiao Ren ◽  
Ping Gong ◽  
Chuanfei Wang ◽  
Yonggang Xue ◽  
...  

Abstract. The Tibetan Plateau (TP) has been contaminated by persistent organic pollutants (POPs), including legacy organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) through atmospheric transport. The exact source regions, transport pathways and time trends of POPs to the TP are not well understood. Here XAD-based passive air samplers (PAS) were deployed at 16 Tibetan background sites from 2007 to 2012 to gain further insight into spatial patterns and temporal trends of OCPs and PCBs. The southeastern TP was characterized by dichlorodiphenyltrichloroethane (DDT) -related chemicals delivered by Indian Monsoon air masses. The northern and northwestern TP displayed the greatest absolute concentration and relative abundance of hexachlorobenzene (HCB) in the atmosphere, caused by the westerly-driven European air masses. The interactions between the DDT polluted Indian monsoon air and the clean westerly winds formed a transition zone in central Tibet where both DDT and HCB were the dominant chemicals. Based on 5-year of continuous sampling, our data indicated declining concentrations of HCB and hexachlorocyclohexanes (HCHs) across the Tibetan region. Inter-annual trends of DDT class chemicals, however, showed less variation during this 5-year sampling period, which may be due to the on-going usage of DDT in India. This paper demonstrates the possibility of using POPs fingerprints to investigate the climate interactions and the validity of using PAS to derive inter-annual atmospheric POPs time trends.


2020 ◽  
Author(s):  
Yingying Sha ◽  
Zhengguo Shi

<p>The Tibetan Plateau (TP) has undoubtedly played an essential role in the evolution and strengthening of the coupled climate system of the Asian monsoon and inland arid climate since the Cenozoic. However, a growing number of studies have found that regional and relatively smaller scale topography also has significant impact on Asian climate.<br>By using high resolution atmospheric circulation model, we analyzed the effect of the main body of the TP and its surrounding topography on the evolution of Asian climate. The surrounding topography includes the Yunnan-Guizhou Plateau (YG) at the southeastern margin of the Tibetan Plateau, the Pamir Plateau (Pr) and Tian Shan mountains (TS) at the northern margin and the Mongolian Plateau (MP) further north. The results show that different from the strengthening effect of the main TP, the YG significantly weakens the Indian monsoon. With the uplift of the YG, an anomalous anticyclonic circulation appeared in the lower troposphere over the southwest, resulting in the weakening of monsoon circulation from the Bay of Bengal to the Indian subcontinent and the Arabian sea. The decline in Indian monsoon precipitation caused by the YG accounts for one-third of the total increase in precipitation caused by the entire TP.<br>For the arid interior Asia, the main TP, YG, Pr and TS, as well as the MP all have reduced the annual precipitation in some extent. However, different from the consistent inhibiting effect of the main TP on the precipitation over the arid interior Asia throughout the year, the decreasing effect of the YG and the MP is mainly effective in boreal winter, which is closely related to the mechanical blocking effect. In addition, the Pr and TS play a key role in the temporal and spatial differentiation of precipitation in the arid interior Asia. Before the appearance of the Pr and TS, the precipitation seasonality over the eastern sub-region was characterized with maximum rainfall in spring and winter and minimum rainfall in summer. With the uplift of Pr and TS, the precipitation over the eastern part decreases in winter and significantly increases in summer, which leads to the change of precipitation seasonality to summer dominated.<br>The above results indicate that different part of the extensive-third pole have different influences on the Asian monsoon and inland aridity. It suggests that the Asian monsoon-inland arid climate may have undergone complex evolutionary processes on tectonic scale.</p>


2017 ◽  
Vol 122 (17) ◽  
pp. 9262-9279 ◽  
Author(s):  
Xiaolong Zhang ◽  
Baiqing Xu ◽  
Franziska Günther ◽  
Roman Witt ◽  
Mo Wang ◽  
...  

2013 ◽  
Vol 26 (7) ◽  
pp. 2279-2287 ◽  
Author(s):  
William R. Boos ◽  
John V. Hurley

Abstract Here it is shown that almost all models participating in the Coupled Model Intercomparison Project (CMIP) exhibit a common bias in the thermodynamic structure of boreal summer monsoons. The strongest bias lies over South Asia, where the upper-tropospheric temperature maximum is too weak, is shifted southeast of its observed location, and does not extend as far west over Africa as it does in observations. Simulated Asian maxima of surface air moist static energy are also too weak and are located over coastal oceans rather than in their observed continental position. The spatial structure of this bias suggests that it is caused by an overly smoothed representation of topography west of the Tibetan Plateau, which allows dry air from the deserts of western Asia to penetrate the monsoon thermal maximum, suppressing moist convection and cooling the upper troposphere. In a climate model with a decent representation of the thermodynamic state of the Asian monsoon, the qualitative characteristics of this bias can be recreated by truncating topography just west of the Tibetan Plateau. This relatively minor topographic modification also produces a negative anomaly of Indian precipitation of similar sign and amplitude to the CMIP continental Indian monsoon precipitation bias. Furthermore, in simulations of next-century climate warming, this topographic modification reduces the amplitude of the increase in Indian monsoon precipitation. These results confirm the importance of topography west of the Tibetan Plateau for South Asian climate and illustrate the need for careful assessments of the thermodynamic state of model monsoons.


2017 ◽  
Vol 457 ◽  
pp. 412-422 ◽  
Author(s):  
Jingmin Li ◽  
Todd A. Ehlers ◽  
Martin Werner ◽  
Sebastian G. Mutz ◽  
Christian Steger ◽  
...  

1993 ◽  
Vol 31 (4) ◽  
pp. 357 ◽  
Author(s):  
Peter Molnar ◽  
Philip England ◽  
Joseph Martinod

2017 ◽  
Vol 30 (4) ◽  
pp. 1259-1272 ◽  
Author(s):  
Zhengguo Shi ◽  
Yingying Sha ◽  
Xiaodong Liu

Abstract Topographic insulation is one of the primary origins for the influence of the Tibetan Plateau (TP) on Asian climate. The Yunnan–Guizhou (YG) Plateau, at the southeastern margin of the TP, is known to block the northern branch of the Indian monsoon circulation in summer. However, it is an open question whether this blocking feeds back to the monsoon. In this study, the effect of the YG topography on the Indian monsoon and its comparison with that of the TP were evaluated using general circulation model experiments. The results showed that the TP strengthens the monsoon precipitation, especially during the onset. However, the YG topography significantly weakens the monsoon. With the YG topography, strengthened low-level airflow around the YG Plateau induces anomalous anticyclonic winds to the southwest, and the changes remodulate the whole circulation structure over Asia. As a result, the Indian monsoon becomes weakened from the Bay of Bengal to the Indian subcontinent and Arabian Sea, as does the associated precipitation. In addition, the YG topography affects the anomalous warming center over the TP and the precipitation during the monsoon onset. The YG-reduced summer precipitation occupied approximately one-third of the total increment compared to the entire TP. The Indian monsoon weakened by YG topography distinctly opposes the traditional paleoclimatic viewpoint that all of the TP topography contributes to the monsoon strengthening. In fact, the climatic effect of the TP depends closely upon both its central and marginal topography, and the topography of its subterrains does not necessarily play a similar role.


2016 ◽  
Vol 16 (11) ◽  
pp. 6901-6911 ◽  
Author(s):  
Xiaoping Wang ◽  
Jiao Ren ◽  
Ping Gong ◽  
Chuanfei Wang ◽  
Yonggang Xue ◽  
...  

Abstract. The Tibetan Plateau (TP) has been contaminated by persistent organic pollutants (POPs), including legacy organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) through atmospheric transport. The exact source regions, transport pathways and time trends of POPs to the TP are not well understood. Here polystyrene–divinylbenzene copolymer resin (XAD)-based passive air samplers (PASs) were deployed at 16 Tibetan background sites from 2007 to 2012 to gain further insight into spatial patterns and temporal trends of OCPs and PCBs. The southeastern TP was characterized by dichlorodiphenyltrichloroethane (DDT)-related chemicals delivered by Indian monsoon air masses. The northern and northwestern TP displayed the greatest absolute concentration and relative abundance of hexachlorobenzene (HCB) in the atmosphere, caused by the westerly-driven European air masses. The interactions between the DDT polluted Indian monsoon air and the clean westerly winds formed a transition zone in central Tibet, where both DDT and HCB were the dominant chemicals. Based on 5 years of continuous sampling, our data indicated declining concentrations of HCB and hexachlorocyclohexanes (HCHs) across the Tibetan region. Inter-annual trends of DDT class chemicals, however, showed less variation during this 5-year sampling period, which may be due to the ongoing usage of DDT in India. This paper demonstrates the possibility of using POP fingerprints to investigate the climate interactions and the validity of using PAS to derive inter-annual atmospheric POP time trends.


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