Dynamic and Thermodynamic Influences of the Tibetan Plateau on the Atmosphere in a General Circulation Model

Abstract The orographic effect of the Tibetan Plateau on atmospheric poleward heat transport is investigated using an atmospheric general circulation model. The linear interference between the Tibetan Plateau–induced winds and the eddy temperature field associated with the land–sea thermal contrast is a key factor for enhancing the poleward stationary eddy heat transport. Specifically, Tibetan Plateau–induced stationary waves produce northerlies over the cold eastern Eurasian continent, leading to a poleward heat transport. In another hot spot of stationary eddy heat transport over the eastern North Pacific, Tibetan Plateau–induced stationary waves transport relatively warm marine air northward. In an experiment where the Tibetan Plateau is removed, the poleward heat transport is mostly accomplished by transient eddies, similar to the Southern Hemisphere. In the presence of the Tibetan Plateau, the enhanced stationary eddy heat transport is offset by a comparable reduction in transient eddy heat transport. This compensation between stationary and transient eddy heat transport is seen in observed interannual variability. Both the model and observations indicate that an enhanced poleward heat transport by stationary waves weakens transient eddies by decreasing the meridional temperature gradient and the associated westerlies in midlatitudes.

Download Full-text

Roles of Anomalous Tibetan Plateau Warming on the Severe 2008 Winter Storm in Central-Southern China

Monthly Weather Review ◽

10.1175/2009mwr2950.1 ◽

2010 ◽

Vol 138 (6) ◽

pp. 2375-2384 ◽

Cited By ~ 35

Author(s):

Qing Bao ◽

Jing Yang ◽

Yimin Liu ◽

Guoxiong Wu ◽

Bin Wang

Keyword(s):

Tibetan Plateau ◽

General Circulation ◽

Extreme Event ◽

Southern China ◽

Inversion Layer ◽

Circulation Model ◽

Central China ◽

The Tibetan Plateau ◽

Freezing Rain ◽

Mean Sea Surface

Abstract Anomalous warming occurred over the Tibetan Plateau (TP) before and during the disastrous freezing rain and heavy snow hitting central and southern China in January 2008. The relationship between the TP warming and this extreme event is investigated with an atmospheric general circulation model. Two perpetual runs were performed. One is forced by the climatological mean sea surface temperatures in January as a control run; and the other has the same model setting as the control run except with an anomalous warming over the TP that mimics the observed temperature anomaly. The numerical results demonstrate that the TP warming induces favorable circulation conditions for the occurrence of this extreme event, which include the deepened lower-level South Asian trough, the enhanced lower-level southwesterly moisture transport in central-southern China, the lower-level cyclonic shear in the southerly flow over southeastern China, and the intensified Middle East jet stream in the middle and upper troposphere. Moreover, the anomalous TP warming results in a remarkable cold anomaly near the surface and a warm anomaly aloft over central China, forming a stable stratified inversion layer that favors the formation of the persistent freezing rain. The possible physical linkages between the TP warming and the relevant resultant circulation anomalies are proposed. The potential reason of the anomalous TP warming during the 2007–08 winter is also discussed.

Download Full-text

Sensitivity of East Asian summer monsoon precipitation to the location of the Tibetan Plateau

Journal of Climate ◽

10.1175/jcli-d-21-0154.1 ◽

2021 ◽

pp. 1-36

Author(s):

Soo-Hyun Seok ◽

Kyong-Hwan Seo

Keyword(s):

Tibetan Plateau ◽

Summer Monsoon ◽

East Asian Summer Monsoon ◽

General Circulation ◽

Asian Summer Monsoon ◽

East Asian ◽

Circulation Model ◽

Dynamical Response ◽

The Tibetan Plateau ◽

Asian Summer

AbstractRecent studies have highlighted that a primary mechanism of the East Asian summer monsoon (EASM) is the fluid dynamical response to the Tibetan Plateau (TP), that is, orographically forced Rossby waves. With this mechanism in mind, this study explores how changes in the location of the TP affect the EASM precipitation. Specifically, the TP is moved in the four cardinal directions using idealized general circulation model experiments. The results show that the monsoon aspects are entirely determined by the location of the TP. Interestingly, the strongest EASM precipitation occurs when the TP is situated near its current location, a situation in which downstream southerlies are well developed from the surface to aloft. However, southerlies into the EASM region weaken as the TP moves, which in turn reduces the precipitation. Nevertheless, as long as it moves in the east–west direction, the TP is likely to force the stationary waves that induce precipitation over the mid-latitudes (not necessarily over East Asia). In contrast, moving the TP well north of its original location does not induce strong monsoon flows over the EASM region, resulting in the driest case. Meanwhile, although the southward movement of the TP triggers downstream southerlies to some extent, it does not lead to an increase in the precipitation. Overall, these results show that the location of the TP is crucial in determining the EASM precipitation, and the latter is much more sensitive to the displacement of the TP in the meridional direction than in the zonal direction.

Download Full-text

Origins of East Asian Summer Monsoon Seasonality

Journal of Climate ◽

10.1175/jcli-d-19-0888.1 ◽

2020 ◽

Vol 33 (18) ◽

pp. 7945-7965 ◽

Cited By ~ 4

Author(s):

J. C. H. Chiang ◽

W. Kong ◽

C. H. Wu ◽

D. S. Battisti

Keyword(s):

Tibetan Plateau ◽

Summer Monsoon ◽

East Asian Summer Monsoon ◽

General Circulation ◽

Asian Summer Monsoon ◽

East Asian ◽

Circulation Model ◽

Northeastern China ◽

The Tibetan Plateau ◽

Asian Summer

AbstractThe East Asian summer monsoon is unique among summer monsoon systems in its complex seasonality, exhibiting distinct intraseasonal stages. Previous studies have alluded to the downstream influence of the westerlies flowing around the Tibetan Plateau as key to its existence. We explore this hypothesis using an atmospheric general circulation model that simulates the intraseasonal stages with fidelity. Without a Tibetan Plateau, East Asia exhibits only one primary convective stage typical of other monsoons. As the plateau is introduced, the distinct rainfall stages—spring, pre-mei-yu, mei-yu, and midsummer—emerge, and rainfall becomes more intense overall. This emergence coincides with a pronounced modulation of the westerlies around the plateau and extratropical northerlies penetrating northeastern China. The northerlies meridionally constrain the moist southerly flow originating from the tropics, leading to a band of lower-tropospheric convergence and humidity front that produces the rainband. The northward migration of the westerlies away from the northern edge of the plateau leads to a weakening of the extratropical northerlies, which, coupled with stronger monsoonal southerlies, leads to the northward migration of the rainband. When the peak westerlies migrate north of the plateau during the midsummer stage, the extratropical northerlies disappear, leaving only the monsoon low-level circulation that penetrates northeastern China; the rainband disappears, leaving isolated convective rainfall over northeastern China. In short, East Asian rainfall seasonality results from the interaction of two seasonally evolving circulations—the monsoonal southerlies that strengthen and extend northward, and the midlatitude northerlies that weaken and eventually disappear—as summer progresses.

Download Full-text

Impacts of Tibetan Plateau uplift on atmospheric dynamics and associated precipitation δ<sup>18</sup>O

10.5194/cp-2015-187 ◽

2016 ◽

Author(s):

S. Botsyun ◽

P. Sepulchre ◽

C. Risi ◽

Y. Donnadieu

Keyword(s):

Tibetan Plateau ◽

General Circulation ◽

Climatic Factors ◽

Precipitation Amount ◽

Modern Science ◽

Circulation Model ◽

Theoretical Expression ◽

The Tibetan Plateau ◽

Reduced Height ◽

Mountain Belts

Abstract. Paleoelevation reconstructions of mountain belts have become a focus of modern science since surface elevation provides crucial information for understanding both geodynamic mechanisms of Earth’s interior and influence of mountains growth on climate. Stable oxygen isotopes paleoaltimetry is one of the most popular techniques nowadays, and relies on the difference between δ18O of paleo-precipitation reconstructed using the natural archives, and modern measured values for the point of interest. Our goal is to understand where and how complex climatic changes linked with the growth of mountains affect δ18O in precipitation. For this purpose, we develop a theoretical expression for the precipitation composition and we use the isotope-equipped atmospheric general circulation model LMDZ-iso. Experiments with reduced height over the Tibetan Plateau and the Himalayas have been designed. Our results show that the isotopic composition of precipitation is very sensitive to climate changes related with the growth of the Himalayas and Tibetan Plateau, notably changes in relative humidity and precipitation amount. The relative contribution of controlling factors and their magnitude differ depending on the uplift stage and the region considered. Thus future paleoaltimetry studies should take into account constraints on climatic factors to avoid misestimating ancient altitudes.

Download Full-text

Revised paleoaltimetry data show low Tibetan Plateau elevation during the Eocene

Science ◽

10.1126/science.aaq1436 ◽

2019 ◽

Vol 363 (6430) ◽

pp. eaaq1436 ◽

Cited By ~ 48

Author(s):

Svetlana Botsyun ◽

Pierre Sepulchre ◽

Yannick Donnadieu ◽

Camille Risi ◽

Alexis Licht ◽

...

Keyword(s):

Stable Isotope ◽

Tibetan Plateau ◽

General Circulation ◽

Circulation Model ◽

Convective Precipitation ◽

The Tibetan Plateau ◽

Model Data ◽

Air Masses ◽

Data Comparison ◽

Oxygen Stable Isotopes

Paleotopographic reconstructions of the Tibetan Plateau based on stable isotope paleoaltimetry methods conclude that most of the Plateau’s current elevation was already reached by the Eocene, ~40 million years ago. However, changes in atmospheric and hydrological dynamics affect oxygen stable isotopes in precipitation and may thus bias such reconstructions. We used an isotope-equipped general circulation model to assess the influence of changing Eocene paleogeography and climate on paleoelevation estimates. Our simulations indicate that stable isotope paleoaltimetry methods are not applicable in Eocene Asia because of a combination of increased convective precipitation, mixture of air masses, and widespread aridity. Rather, a model-data comparison suggests that the Tibetan Plateau only reached low to moderate (less than 3000 meters) elevations during the Eocene, reconciling oxygen isotope data with other proxies.

Download Full-text

Summer Temperature over the Tibetan Plateau Modulated by Atlantic Multidecadal Variability

Journal of Climate ◽

10.1175/jcli-d-17-0858.1 ◽

2019 ◽

Vol 32 (13) ◽

pp. 4055-4067 ◽

Cited By ~ 6

Author(s):

Chunming Shi ◽

Cheng Sun ◽

Guocan Wu ◽

Xiuchen Wu ◽

Deliang Chen ◽

...

Keyword(s):

Tibetan Plateau ◽

General Circulation ◽

Ring Width ◽

Circulation Model ◽

The Tibetan Plateau ◽

Positive Temperature ◽

Permafrost Degradation ◽

Atlantic Multidecadal Variability ◽

Multidecadal Variability ◽

Instrumental Records

Abstract Rapid warming has led to an aggregated environmental degradation over the Tibetan Plateau (TP) in the last few decades, including accelerated glacier retreat, early snowmelt, permafrost degradation, and forest fire occurrence. Attribution of this warming in recent decades has mainly been focused on anthropogenic forcing. Yet, linkages to the Atlantic multidecadal variability (AMV), an essential part of the climate system causing decadal to centennial fluctuations of temperature, remains poorly understood for the TP, especially at long time scales. Using well-replicated tree-ring width records, we reconstructed 358 years of summer minimum temperature (MinT) of the whole TP. This reconstruction matches the recent warming signal recorded since the 1980s, and captures 63% of the variance in 1950–2005 instrumental records. A teleconnection from the North Atlantic to the TP is further identified based in observations and simulations with an atmospheric general circulation model (AGCM). We propose that half of the multidecadal variability of TP summer MinT can be explained by the AMV over the past three and a half centuries. Both observations and AGCM simulations indicate that the AMV warm phase induces a zonal dipole response in sea level pressure across the Atlantic–Eurasia region, with anomalously high surface pressure and corresponding downward atmospheric motion over the TP. We propose that the descending motion during warm AMV phases causes negative rainfall and positive temperature anomalies over the TP. Our findings highlight that the AMV plays a role in the multidecadal temperature variability over the TP.

Download Full-text

Impact of Subgrid-Scale Orography on Equatorial Angular Momentum Budget and the Cold Surges in a General Circulation Model

Monthly Weather Review ◽

10.1175/mwr-d-14-00233.1 ◽

2015 ◽

Vol 143 (11) ◽

pp. 4443-4458

Author(s):

Sylvain Mailler ◽

François Lott

Keyword(s):

Angular Momentum ◽

General Circulation Model ◽

General Circulation ◽

Large Scale ◽

Circulation Model ◽

The Tibetan Plateau ◽

Subgrid Scale ◽

Synoptic Conditions ◽

Cold Surges ◽

The One

Abstract The dynamical relations between equatorial atmospheric angular momentum (EAAM), equatorial mountain torques, and cold surges are analyzed in a general circulation model (GCM). First, the authors show that the global EAAM budget is well closed in the GCM, much better than in the NCEP–NCAR reanalysis. They then confirm that the equatorial torques due to the Tibetan Plateau, the Rockies, and the Andes are well related to the cold surges developing over East Asia, North America, and South America, respectively. For all these mountains, a peak in the equatorial mountain torque components precedes by few days the development of a cold surge, confirming that the cold surge’s “preconditioning” is dynamically driven by large-scale mountains. The authors also analyze the contribution of the subgrid-scale orography (SSO) parameterizations and find that they contribute substantially to the torques. In experiments where these parameterizations are almost entirely reduced over a given massif, the authors find that the explicit pressure torques produced by that massif largely compensate the reduction in the parameterized torques. On the one hand, this proves that the explicitly resolved equatorial mountain torques are effective dynamical drivers of the flow dynamics, since they are enhanced when a parameterized torque is reduced. On the other hand, this shows that the cold surges can be captured in GCMs, provided that the synoptic conditions prior to their onset are realistic. The compensation between torques is nevertheless not complete and some weakening of the cold surges is found when the parameterized mountain torques are reduced.

Download Full-text