scholarly journals Decreasing wind speed and weakening latitudinal surface pressure gradients in the Tibetan Plateau

2010 ◽  
Vol 42 (1) ◽  
pp. 57-64 ◽  
Author(s):  
Q You ◽  
S Kang ◽  
WA Flügel ◽  
N Pepin ◽  
Y Yan ◽  
...  
Keyword(s):  
Wind Speed ◽  
Tibetan Plateau ◽  
Surface Pressure ◽  
The Tibetan Plateau ◽  
Pressure Gradients

scholarly journals Atmospheric Thermal and Dynamic Vertical Structures of Summer Hourly Precipitation in Jiulong of the Tibetan Plateau

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 505
Author(s):  
Yonglan Tang ◽  
Guirong Xu ◽  
Rong Wan ◽  
Xiaofang Wang ◽  
Junchao Wang ◽  
...  
Keyword(s):  
Wind Speed ◽  
Tibetan Plateau ◽  
Precipitation Amount ◽  
Summer Precipitation ◽  
The Tibetan Plateau ◽  
Hourly Precipitation ◽  
Air Convection ◽  
Precipitation Variation ◽  
Long Term Observation

It is an important to study atmospheric thermal and dynamic vertical structures over the Tibetan Plateau (TP) and their impact on precipitation by using long-term observation at representative stations. This study exhibits the observational facts of summer precipitation variation on subdiurnal scale and its atmospheric thermal and dynamic vertical structures over the TP with hourly precipitation and intensive soundings in Jiulong during 2013–2020. It is found that precipitation amount and frequency are low in the daytime and high in the nighttime, and hourly precipitation greater than 1 mm mostly occurs at nighttime. Weak precipitation during the daytime may be caused by air advection, and strong precipitation at nighttime may be closely related with air convection. Both humidity and wind speed profiles show obvious fluctuation when precipitation occurs, and the greater the precipitation intensity, the larger the fluctuation. Moreover, the fluctuation of wind speed is small in the morning, large at noon and largest at night, presenting a similar diurnal cycle to that of convective activity over the TP, which is conductive to nighttime precipitation. Additionally, the inverse layer is accompanied by the inverse humidity layer, and wind speed presents multi-peaks distribution in its vertical structure. Both of these are closely related with the underlying surface and topography of Jiulong. More studies on physical mechanism and numerical simulation are necessary for better understanding the atmospheric phenomenon over the TP.

scholarly journals East Asian Summer Monsoon Precipitation Response to Variations in Upstream Westerly Wind

2021 ◽  
Author(s):  
Jun-Hyeok Son ◽  
Kyong-Hwan Seo
Keyword(s):  
Wind Speed ◽  
Tibetan Plateau ◽  
Interannual Variability ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
The Tibetan Plateau ◽  
Westerly Wind ◽  
Dynamical Mechanism ◽  
Asian Summer

Abstract From spring to summer, the East Asian summer monsoon (EASM) rainband migrates northwestward. During summer, East Asian countries experience extensive precipitation due to the EASM rainband, but the springtime monsoon rainband lies over the Pacific. The seasonal evolution of the EASM rainband is influenced by the mechanical effect of the Tibetan Plateau, and seasonal changes in the westerly wind speeds impinging on the Tibetan Plateau are a key driver of this process. In this study, using interannual variability of the upstream zonal wind speed, the dynamical mechanism for the interannual variations of the EASM precipitation is revealed based on the topographically forced stationary Rossby wave theory. The dynamical mechanism regulating interannual variability in the EASM rainband is essentially the same mechanism that drives the seasonal evolution of the climatological EASM rainband. If the westerly winds impinging on the Tibetan Plateau are stronger (weaker) than average, then the EASM rainband shifts eastward (westward). Large variations in the upstream westerly wind during May induced considerable interannual variation in the zonal location of the rainband (up to a 20–30º shift). The westerly wind speed exhibited less variations in June and July, resulting in a smaller zonal shift of approximately 10º.

scholarly journals Surface pressure and elevation correction from observation and multiple reanalyses over the Tibetan Plateau

2019 ◽  
Vol 53 (9-10) ◽  
pp. 5893-5908
Author(s):  
Qinglong You ◽  
Yuntao Bao ◽  
Zhihong Jiang ◽  
Nick Pepin ◽  
G. W. K. Moore
Keyword(s):  
Tibetan Plateau ◽  
Surface Pressure ◽  
The Tibetan Plateau ◽  
Elevation Correction

scholarly journals Seasonality and spatial variability of dynamic precipitation controls on the Tibetan Plateau

2016 ◽  
Vol 7 (3) ◽  
pp. 767-782 ◽  
Author(s):  
Julia Curio ◽  
Dieter Scherer
Keyword(s):  
Wind Speed ◽  
Tibetan Plateau ◽  
Spatial Variability ◽  
Water Cycle ◽  
High Mountain ◽  
The Tibetan Plateau ◽  
Dominant Type ◽  
Precipitation Distribution ◽  
Mountain Ranges ◽  
Vertical Wind Speed

Abstract. The Tibetan Plateau (TP) is the origin of many large Asian rivers, which provide water resources for large regions in south and east Asia. Therefore, the water cycle on the TP and adjacent high mountain ranges, in particular the precipitation distribution and variability play an important role for the water availability for billions of people in the downstream regions of the TP. The High Asia Refined analysis (HAR) is used to analyse the dynamical factors that influence precipitation variability in the TP region, including the factors resulting in the enhancement and suppression of precipitation. Four dynamical fields that can influence precipitation are considered: the 300 hPa wind speed and wind speed 2 km above ground, the 300 hPa vertical wind speed, and the atmospheric water transport. The study focusses on the seasonality and the spatial variability of the precipitation controls and their dominant patterns. Results show that different factors have different effects on precipitation in different regions and seasons. This depends mainly on the dominant type of precipitation, i.e. convective or frontal/cyclonic precipitation. Additionally, the study reveals that the midlatitude westerlies have a high impact on the precipitation distribution on the TP and its surroundings year-round and not only in winter.

Statistics and analysis of high-altitude wind above the western Tibetan Plateau

2020 ◽  
Vol 498 (4) ◽  
pp. 5786-5797
Author(s):  
Xuan Qian ◽  
Yongqiang Yao ◽  
Hongshuai Wang ◽  
Lei Zou ◽  
Yao Li
Keyword(s):  
Wind Speed ◽  
Tibetan Plateau ◽  
High Altitude ◽  
Adaptive Optics ◽  
Wrf Model ◽  
The Tibetan Plateau ◽  
Scale Models ◽  
Western Tibetan Plateau ◽  
Wind Profiles ◽  
Meso Scale

ABSTRACT This article aims at studying the characteristics of high-altitude wind at the Ali Observatory on the western Tibetan Plateau, as the high-altitude wind has been put forward as a critical parameter for site evaluation, especially for adaptive optics. We have run a meso-scale numerical weather research and forecasting (WRF) model in three nested domains with different horizontal resolutions, centred at the Ali Observatory; the model results with the highest horizontal resolution of 1 km and temporal resolution of 0.5 h are presented, and also statistical analyseis of vertical wind profiles and 200 hPa wind speed are performed. Moreover, comparisons of wind speeds obtained from model and radiosoundings are presented; as the vertical resolution has been proved to be key to the estimation of optical turbulence with meso-scale models, the vertical resolutions are both set to 50 m for wind profiles, which reveals a high level of agreement and provides a useful tool for site assessment. The results prove the good character of the high-altitude wind over the Ali region, especially in summer half year, with a yearly median 200 hPa wind speed of 33.6 m s−1 in 2016, and also provide proof of the potential advantage of the Ali Observatory for adaptive optics. Furthermore, we certify that meso-scale models can offer dependable estimation of high-altitude wind over the Tibetan Plateau; the wind simulations provided by the WRF model will be of great benefit for adaptive optics, which also provides the vertical distributions of CN2 and τ0 above astronomical observatories.

scholarly journals Spatio-Temporal Variation of Reference Evapotranspiration and Its Climatic Drivers over the Tibetan Plateau during 1970–2018

2021 ◽  
Vol 11 (17) ◽  
pp. 8013
Author(s):  
Shanshan Hu ◽  
Ruyi Gao ◽  
Tao Zhang ◽  
Peng Bai ◽  
Rui Zhang
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Tibetan Plateau ◽  
Reference Evapotranspiration ◽  
Climatic Factors ◽  
Kendall Test ◽  
The Tibetan Plateau ◽  
Variation Characteristics ◽  
Climatic Drivers ◽  
Spatio Temporal

Reference evapotranspiration (ET0) is a key component of hydrologic cycle and it is important for water resources management. Analysis of ET0 changes is particularly critical for understanding the impacts of climatic change on hydrology in ecologically fragile regions. In this study, using the Penman–Monteith method and the Mann–Kendall test, the variation characteristics of ET0 on the Tibetan Plateau (TP) from 1970 to 2018 was analyzed, and the dominant climatic factors controlling the change of ET0 was also explored. The result shows that in TP region: (1) there was an abrupt change in the trend of ET0 around 1997, and the ET0 declined at a rate of −25.9 mm/decade during 1970–1996 but increased by 31.1 mm/decade during 1997–2018; (2) ET0 is most sensitive to solar radiation, then relative humidity, wind speed and mean temperature; (3) the decrease of ET0 before 1997 was mainly due to the decline of wind speed and the increase of relative humidity, while the increase of ET0 after 1997 was mainly due to the decrease of relative humidity. The results of this study can provide data reference for the research of water balance on the TP.

Observed Coherent Trends of Surface and Upper-Air Wind Speed over China since 1960

2013 ◽  
Vol 26 (9) ◽  
pp. 2891-2903 ◽  
Author(s):  
Changgui Lin ◽  
Kun Yang ◽  
Jun Qin ◽  
Rong Fu
Keyword(s):  
Wind Speed ◽  
Tibetan Plateau ◽  
Regional Scale ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Spatial Gradient ◽  
The Tibetan Plateau ◽  
Strong Wind ◽  
Wind Speeds ◽  
The Past

Abstract Previous studies indicated that surface wind speed over China declined during past decades, and several explanations exist in the literature. This study presents long-term (1960–2009) changes of both surface and upper-air wind speeds over China and addresses observed evidence to interpret these changes. It is found that surface wind over China underwent a three-phase change over the past 50 yr: (i) it step changed to a strong wind level at the end of the 1960s, (ii) it declined until the beginning of the 2000s, and (iii) it seemed to be steady and even recovering during the very recent years. The variability of surface wind speed is greater at higher elevations and less at lower elevations. In particular, surface wind speed over the elevated Tibetan Plateau has changed more significantly. Changes in upper-air wind speed observed from rawinsonde are similar to surface wind changes. The NCEP–NCAR reanalysis indicates that wind speed changes correspond to changes in geopotential height gradient at 500 hPa. The latter are further correlated with the changes of latitudinal surface temperature gradient, with a correlation coefficient of 0.88 for the past 50 yr over China. This strongly suggests that the spatial gradient of surface global warming or cooling may significantly change surface wind speed at a regional scale through atmospheric thermal adaption. The recovery of wind speed since the beginning of the 2000s over the Tibetan Plateau might be a precursor of the reversal of wind speed trends over China, as wind over high elevations can respond more rapidly to the warming gradient and atmospheric circulation adjustment.

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