scholarly journals Why Has the Inner Tibetan Plateau Become Wetter since the Mid-1990s?

2020 ◽  
Vol 33 (19) ◽  
pp. 8507-8522 ◽  
Author(s):  
Jing Sun ◽  
Kun Yang ◽  
Weidong Guo ◽  
Yan Wang ◽  
Jie He ◽  
...  
Keyword(s):  
Water Vapor ◽  
Tibetan Plateau ◽  
North Atlantic Ocean ◽  
Wave Train ◽  
Summer Precipitation ◽  
Atlantic Multidecadal Oscillation ◽  
Rapid Expansion ◽  
The Tibetan Plateau ◽  
The North ◽  
Westerly Jet

AbstractThe Inner Tibetan Plateau (ITP; also called the Qiangtang Plateau) appears to have experienced an overall wetting in summer (June, July, and August) since the mid-1990s, which has caused the rapid expansion of thousands of lakes. In this study, changes in atmospheric circulations associated with the wetting process are analyzed for 1979–2018. These analyses show that the wetting is associated with simultaneously weakened westerlies over the Tibetan Plateau (TP). The latter is further significantly correlated with the Atlantic multidecadal oscillation (AMO) on interdecadal time scales. The AMO has been in a positive phase (warm anomaly of the North Atlantic Ocean sea surface) since the mid-1990s, which has led to both a northward shift and weakening of the subtropical westerly jet stream at 200 hPa near the TP through a wave train of cyclonic and anticyclonic anomalies over Eurasia. These anomalies are characterized by an anomalous anticyclone to the east of the ITP and an anomalous cyclone to the west of the ITP. The former weakens the westerly winds, trapping water vapor over the ITP while the latter facilitates water vapor intruding from the Arabian Sea into the ITP. Accordingly, summer precipitation over the ITP has increased since the mid-1990s.

scholarly journals Influence of Tibetan Plateau On The North American Summer Monsoon Precipitation

2021 ◽  
Author(s):  
Qin Wen ◽  
Zixuan Han ◽  
Hajun Yang ◽  
Jianbo Cheng ◽  
Zhengyu Liu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Summer Monsoon ◽  
North Atlantic ◽  
North American ◽  
Wave Train ◽  
Meridional Overturning Circulation ◽  
Hadley Cell ◽  
Dynamical Process ◽  
The Tibetan Plateau ◽  
The North

Abstract It has been well known that the uplift of the Tibetan Plateau (TP) can significantly enhance the Asian monsoon. Here, by comparing the sensitivity experiments with vs without the TP, we find that TP uplift can also increase the precipitation of North American Summer Monsoon (NASM), with atmosphere teleconnection accounting for 6% and oceanic dynamical process accounting for another 6%. Physically, TP uplift generates a stationary Rossby wave train traveling from Asian continent to the North Atlantic region, resulting in an anomalous high-pressure over tropical-subtropical North Atlantic. The anomalous subtropical high enhances the low level southerly winds, forcing an anomalous upward motion over North American monsoon (NAM) region and then an increased summer precipitation there. In addition, TP uplift enhances the Atlantic meridional overturning circulation, which reduces the meridional temperature gradient and leads to a northward shift of Hadley Cell over eastern Pacific-Atlantic section. The latter shifts the convection center northward to 10°N and further increases the NASM precipitation. The enhanced NASM precipitation can also be understood by the northward shift of Intertropical Convergence Zone. Our study implies that the changes of NAM climate can be affected by not only local process but also remote forcing, including the Asian highland.

The AMV phase-dependence of the connection between February NAO and March surface air temperature over the Tibetan Plateau

2021 ◽  
Author(s):  
Jingyi Li ◽  
Fei Li ◽  
Shengping He ◽  
Huijun Wang ◽  
Yvan J Orsolini
Keyword(s):  
Tibetan Plateau ◽  
Air Temperature ◽  
Rossby Wave ◽  
North Atlantic ◽  
Wave Train ◽  
Surface Air Temperature ◽  
The Tibetan Plateau ◽  
The North ◽  
Rossby Wave Train ◽  
The North Atlantic

<p>The Tibetan Plateau (TP), referred to as the “Asian water tower”, contains one of the largest land ice masses on Earth. The local glacier shrinkage and frozen-water storage are strongly affected by variations in surface air temperature over the TP (TPSAT), especially in springtime. This study reveals a distinct out-of-phase connection between the February North Atlantic Oscillation (NAO) and March TPSAT, which is non-stationary and regulated by the warm phase of the Atlantic Multidecadal Variability (AMV+). The results show that during the AMV+, the negative phase of the NAO persists from February to March, and is accompanied by a quasi-stationary Rossby wave train trapped along a northward-shifted subtropical westerly jet stream across Eurasia, inducing an anomalous adiabatic descent that warms the TP. However, during the cold phase of the AMV, the negative NAO does not persist into March. The Rossby wave train propagates along the well-separated polar and subtropical westerly jets, and the NAO−TPSAT connection is broken. Further investigation suggests that the enhanced synoptic eddy and low-frequency flow (SELF) interaction over the North Atlantic in February and March during the AMV+, caused by the enhanced and southward-shifted storm track, help maintain the NAO anomaly pattern via positive eddy feedback. This study provides a new detailed perspective on the decadal variability of the North Atlantic−TP connections in late winter−early spring.</p>

Role of Tibetan Plateau in Northern Drought induced by Changes in Subtropical Westerly Jet

2021 ◽  
pp. 1-40
Author(s):  
Qingzhe Zhu ◽  
Yuzhi Liu ◽  
Tianbin Shao ◽  
Run Luo ◽  
Ziyuan Tan
Keyword(s):  
Water Vapor ◽  
Tibetan Plateau ◽  
North China ◽  
Lower Troposphere ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
The Tibetan Plateau ◽  
Westerly Jet ◽  
The Impact ◽  
Subtropical Westerly Jet

AbstractThe Tibetan Plateau (TP), the “Water Tower of Asia”, plays an important role in the water cycle. However, few studies have linked the TP’s water vapor supply with the climate over North China. In this study, we found that changes in the subtropical westerly jet (SWJ) dynamically induce drought in North China, and the TP plays an important role in this relationship. During July-August for the period of 1981-2019, the SWJ center between 75°E and 105°E obviously shifted northward at a rate of 0.04° per year. Correspondingly, the zonal winds in the southern subtropics were incredibly weakened, causing the outflow of water vapor from the TP to decrease dramatically. Combined with numerical simulations, we discovered that a reduction in water vapor transport from the TP can obviously decrease the precipitation over North China. Sensitivity experiments demonstrated that if the water vapor outflow from the eastern border of the TP decreases by 52.74%, the precipitation in North China will decrease by 12.69% due to a decrease in the local cloud fraction caused by a diminished water vapor content in the atmosphere. Therefore, although less water vapor transport occurs in the upper troposphere than in the lower troposphere, the impact of transport from the TP in the former on the downstream precipitation cannot be ignored.

Indian irrigation effects on precipitation over the Tibetan Plateau

2020 ◽  
Author(s):  
Yaqiong Lu ◽  
Shan Lin
Keyword(s):  
Heat Flux ◽  
Water Vapor ◽  
Tibetan Plateau ◽  
Climate Model ◽  
Regional Climate ◽  
Sensible Heat Flux ◽  
Summer Precipitation ◽  
Back Trajectory ◽  
The Tibetan Plateau ◽  
Irrigation Effects

<p>Indian agriculture equipped the most intensive irrigation worldwide and still maintains an increasing trend of irrigation due to the decreasing of Indian summer monsoon rainfall. Irrigation could largely increase soil moisture and evapotranspiration while cooling air temperature. Several researches showed that Indian irrigation did not significantly contribute to local precipitation, so will the Indian irrigation affect the adjacent regions, such as the Tibetan Plateau is unclear. Here, we set up 10-years simulations for two nested domains (30-10km) over the South-East Asia to quantify the irrigation effects with a coupled dynamic crop model and regional climate model (WRF4.0-CLM4Crop). Besides the numeric simulations, we adopted a water vapor back trajectory tracking method to track where the evaporation from the irrigated land fall as precipitation. Our preliminary results showed that Indian irrigation did not significantly affects temperature, sensible heat flux, and latent heat flux over the Tibetan Plateau, but the water vapor from Indian irrigation contributed to 10% of the summer precipitation on the Tibetan Plateau.</p>

scholarly journals Development and evaluation of spectral nudging strategy for the simulation of summer precipitation over the Tibetan Plateau using WRF (v4.0)

2021 ◽  
Vol 14 (5) ◽  
pp. 2827-2841
Author(s):  
Ziyu Huang ◽  
Lei Zhong ◽  
Yaoming Ma ◽  
Yunfei Fu
Keyword(s):  
Climate Change ◽  
Water Vapor ◽  
Tibetan Plateau ◽  
Regional Climate ◽  
Summer Precipitation ◽  
Horizontal Wind ◽  
The Tibetan Plateau ◽  
Model Simulations ◽  
Driving Field ◽  
Spectral Nudging

Abstract. Precipitation is the key component determining the water budget and climate change of the Tibetan Plateau (TP) under a warming climate. This high-latitude region is regarded as “the Third Pole” of the Earth and the “Asian Water Tower” and influences the eco-economy of downstream regions. However, the intensity and diurnal cycle of precipitation are inadequately depicted by current reanalysis products and regional climate models (RCMs). Spectral nudging is an effective dynamical downscaling method used to improve precipitation simulations of RCMs by preventing simulated fields from drifting away from large-scale reference fields, but the most effective manner of applying spectral nudging over the TP is unclear. In this paper, the effects of spectral nudging parameters (e.g., nudging variables, strengths, and levels) on summer precipitation simulations and associated meteorological variables were evaluated over the TP. The results show that using a conventional continuous integration method with a single initialization is likely to result in the over-forecasting of precipitation events and the over-forecasting of horizontal wind speeds over the TP. In particular, model simulations show clear improvements in their representations of downscaled precipitation intensity and its diurnal variations, atmospheric temperature, and water vapor when spectral nudging is applied towards the horizontal wind and geopotential height rather than towards the potential temperature and water vapor mixing ratio. This altering of the spectral nudging method not only reduces the wet bias of water vapor in the lower troposphere of the ERA-Interim reanalysis (when it is used as the driving field) but also alleviates the cold bias of atmospheric temperatures in the upper troposphere, while maintaining the accuracy of horizontal wind features for the regional model field. The conclusions of this study imply how driving field errors affect model simulations, and these results may improve the reliability of RCM results used to study the long-term regional climate change.

scholarly journals Improvement in the Prediction of Summer Precipitation in the North China−Hetao Region Using the Tropospheric Temperature Over the Tibetan Plateau in Spring

2021 ◽  
Vol 9 ◽  
Author(s):  
Dan Chen ◽  
Sulan Nan ◽  
Ge Liu ◽  
Changyan Zhou ◽  
Renrui Shi ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
East Asia ◽  
North China ◽  
Summer Precipitation ◽  
Asia Pacific ◽  
The Tibetan Plateau ◽  
Tropospheric Temperature ◽  
The North ◽  
The Impact ◽  
The Relationship

We investigated the relationship between the spring tropospheric temperature over the Tibetan Plateau (TPT) and summer precipitation in eastern China on an interannual timescale using the monthly mean ERA-Interim reanalysis dataset, the HadISST dataset and the daily mean precipitation dataset for China. We found that there is a significant positive correlation between the spring TPT and summer precipitation in the North China−Hetao region. The relationship is manifested in the context of the East Asia–Pacific pattern teleconnection. In the high spring TPT index years, the geopotential height anomalies over East Asia and the western North Pacific present a negative phase of the East Asia–Pacific pattern teleconnection in the subsequent summer. This circulation pattern is beneficial for the water vapor transport from the western Pacific to inland, which further transport to the North China−Hetao region from the Yangtze River–Yellow rivers region. Anomalous upward motion occurs in the North China–Hetao region, which increases precipitation. The East Asian subtropical westerly jet shifts further north and the South Asian high weakens and shrinks westward. These conditions all favor an increase in precipitation over the North China–Hetao region. The spring TPT plays an important part in the prediction of summer precipitation in the North China−Hetao region. The improvement in the use of the spring TPT to predict summer precipitation in the North China–Hetao region is examined by comparing the prediction equations with and without the prediction factor of the spring TPT on the basis of the sea surface temperatures in key regions. After considering the impact of the spring TPT, the explanatory variance of the prediction equation for precipitation in the North China–Hetao region increases by 17.3%.

scholarly journals Increasing warm-season precipitation in Asian drylands and response to reducing spring snow cover over the Tibetan Plateau

2021 ◽  
pp. 1-69
Author(s):  
Jie Zhang ◽  
Qianrong Ma ◽  
Haishan Chen ◽  
Siwen Zhao ◽  
Zhiheng Chen
Keyword(s):  
Water Vapor ◽  
Tibetan Plateau ◽  
Snow Cover ◽  
Northeast Asia ◽  
Warm Season ◽  
Summer Precipitation ◽  
South Asian High ◽  
The Tibetan Plateau ◽  
Water Vapor Flux ◽  
Vapor Flux

AbstractPrecipitation is crucial for life and the ecological environment in Asian drylands. This study investigated precipitation trends in Asian drylands in previous four decades and simulated its possible linkage with snow cover reduction over the Tibetan Plateau. The results show that precipitation has been increasing and contributing to wetter conditions in Asian drylands. The increasing trends can be attributed to the deepened quasi-stationary wave trough around the Lake Balkhash and the meridional water-vapor flux originated from the Arabian Sea and the Bay of Bengal. The mid-latitude waves and eddy disturbances correspond to the northward upper-level Tibetan Plateau (TP) mode of the South Asian High (TP-SAH) and the Afro-Asia jet with cyclonic rotation. Both SAH and Afro-Asia jet anomalies strengthen the ascending motion and northward water-vapor convergence in Asian drylands, and those are favorable for summer precipitation. The anomalous circulations are linked to the following: (1) the reduced snow cover (SC) over the west TP in the late spring results in decreasing soil moisture and increasing diabatic heating in summer and favors northward extension of TP-SAH and the Afro-Asia jet; (2) the reduced TP/SC increases surface temperature over TP and northeast Asia, which decreases the temperature gradient between the TP and the Indian Ocean, between northeast Asia and East Asia. Decreased temperature gradients are beneficial to the southwest-northeast cyclonic rotation of Afro-Asia jet and consequently strengthen the southerly wind and northward water-vapor flux over TP and surrounding regions. This study emphasizes important effects of the reducing TP/SC on intensifying summer precipitation in Asian drylands.

scholarly journals Interdecadal Climate Variations Controlling the Water Level of Lake Qinghai over the Tibetan Plateau

2017 ◽  
Vol 18 (11) ◽  
pp. 3013-3025 ◽  
Author(s):  
Lin Zhao ◽  
S.-Y. Simon Wang ◽  
Jonathan Meyer
Keyword(s):  
Water Vapor ◽  
Tibetan Plateau ◽  
Water Level ◽  
Wave Train ◽  
Cold Season ◽  
Water Levels ◽  
The Tibetan Plateau ◽  
Lake Qinghai ◽  
Anthropogenic Aerosols ◽  
Budget Analysis

Abstract Using observed and reanalysis data, the pronounced interdecadal variations of Lake Qinghai (LQH) water levels and associated climate factors were diagnosed. From the 1960s to the early 2000s, the water level of LQH in the Tibetan Plateau has experienced a continual decline of 3 m but has since increased considerably. A water budget analysis of the LQH watershed suggested that the water vapor flux divergence is the dominant atmospheric process modulating precipitation and subsequently the lake volume change . The marked interdecadal variability in and was found to be related to the North Pacific (NP) and Pacific decadal oscillation (PDO) modes during the cold season (November–March). Through empirical orthogonal function (EOF) and regression analyses, the water vapor sink over the LQH watershed also responds significantly to the summer Eurasian wave train modulated by the low-frequency variability associated with the cold season NP and PDO modes. Removal of these variability modes (NP, PDO, and the Eurasian wave train) led to a residual uptrend in the hydrological variables of , , and precipitation, corresponding to the net water level increase. Attribution analysis using the Coupled Model Intercomparison Project phase 5 (CMIP5) single-forcing experiments shows that the simulations driven by greenhouse gas forcing produced a significant increase in the LQH precipitation, while anthropogenic aerosols generated a minor wetting trend as well.

scholarly journals A Dipole Pattern of Summertime Rainfall across the Indian Subcontinent and the Tibetan Plateau

2017 ◽  
Vol 30 (23) ◽  
pp. 9607-9620 ◽  
Author(s):  
Xingwen Jiang ◽  
Mingfang Ting
Keyword(s):  
Water Vapor ◽  
Tibetan Plateau ◽  
Indian Subcontinent ◽  
Wave Train ◽  
Water Vapor Transport ◽  
Interactive System ◽  
The Tibetan Plateau ◽  
Dipole Pattern ◽  
Northern Bay Of Bengal ◽  
Anomalous Anticyclonic Circulation

The Tibetan Plateau (TP) has long been regarded as a key driver for the formation and variations of the Indian summer monsoon (ISM). Recent studies, however, have indicated that the ISM also exerts a considerable impact on rainfall variations in the TP, suggesting that the ISM and the TP should be considered as an interactive system. From this perspective, the covariability of the July–August mean rainfall across the Indian subcontinent (IS) and the TP is investigated. It is found that the interannual variation of IS and TP rainfall exhibits a dipole pattern in which rainfall in the central and northern IS tends to be out of phase with that in the southeastern TP. This dipole pattern is associated with significant anomalies in rainfall, atmospheric circulation, and water vapor transport over the Asian continent and nearby oceans. Rainfall anomalies and the associated latent heating in the central and northern IS tend to induce changes in regional circulation that suppress rainfall in the southeastern TP and vice versa. Furthermore, the sea surface temperature anomalies in the tropical southeastern Indian Ocean can trigger the dipole rainfall pattern by suppressing convection over the central IS and the northern Bay of Bengal, which further induces anomalous anticyclonic circulation to the south of TP that favors more rainfall in the southeastern TP by transporting more water vapor to the region. The dipole pattern is also linked to the Silk Road wave train via its link to rainfall over the northwestern IS.

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