Spatiotemporal distribution and variation of wind erosion over the Tibetan Plateau based on a coupled land-surface wind-erosion model

2021 ◽  
Vol 50 ◽  
pp. 100699
Author(s):  
Yingsha Jiang ◽  
Yanhong Gao ◽  
Cenlin He ◽  
Benli Liu ◽  
Yongjie Pan ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Land Surface ◽  
Wind Erosion ◽  
Surface Wind ◽  
Spatiotemporal Distribution ◽  
The Tibetan Plateau ◽  
Erosion Model

scholarly journals Impacts of the Westerlies on Planetary Boundary Layer Growth Over a Valley on the North Side of the Central Himalayas

2021 ◽  
Author(s):  
Xuelong Chen
Keyword(s):  
Tibetan Plateau ◽  
Wind Direction ◽  
Land Surface ◽  
Large Scale ◽  
Vertical Structure ◽  
Surface Wind ◽  
The Tibetan Plateau ◽  
The North ◽  
Synoptic Wind ◽  
Synoptic Circulation

<p>The spatial-temporal structure of the Planetary Boundary Layer (PBL) over mountainous areas can be strongly modified by topography. The PBL over the mountainous terrain of the Tibetan Plateau (TP) is more complex than that observed over its flat areas. To date, there have been no detailed analyses which have taken into account the topography effects exerted on PBL growth over the Tibetan Plateau (TP). A clear understanding of the processes involved in the PBL growth and depth over the TP’s mountainous areas is therefore long overdue.The PBL in the Himalayan region of the Tibetan Plateau (TP) is important to the study of interaction between the area’s topography and synoptic circulation.</p><p>This study used radiosonde, <em>in-situ</em> measurements, ERA5 reanalysis dataset and numerical model to investigate the vertical structure of the PBL and the land surface energy balance in the Rongbuk Valley on the north of the central Himalaya, and their association with the Westerlies, which control the climate of the Himalaya in winters. Two sunny November days in 2014 with different synoptic conditions in terms of large-scale wind direction and speed were selected to investigate the ways in which large-scale synoptic forcing affected the vertical structure of the PBL, atmospheric stability, surface wind field, and land surface energy fluxes. The results revealed that the valley winds and PBL growth were strongly influenced by the variations of the westerlies. When the synoptic wind direction at the height of the mountain ridges was parallel to the axis of the valley, the downward transmission of the westerlies to the valley floor (DTWTV) was strong and cause high near-surface wind speeds and sensible heat flux value, then produced an extremely deep PBL (9 km above sea level) in the early afternoon of November 23. When the synoptic wind direction at the ridge height intersected the axis of the valley and was weak, the DTWTV was weak, and the PBL became relatively low on November 28. These results demonstrate that the interaction between the topography and synoptic circulation plays a critical role in PBL growth.</p>

Trends of land surface heat fluxes on the Tibetan Plateau from 2001 to 2012

2017 ◽  
Vol 37 (14) ◽  
pp. 4757-4767 ◽  
Author(s):  
Cunbo Han ◽  
Yaoming Ma ◽  
Xuelong Chen ◽  
Zhongbo Su
Keyword(s):  
Tibetan Plateau ◽  
Land Surface ◽  
Surface Heat ◽  
Heat Fluxes ◽  
The Tibetan Plateau ◽  
Surface Heat Fluxes ◽  
Land Surface Heat Fluxes

scholarly journals Cumulus over the Tibetan Plateau in the Summer Based on CloudSat–CALIPSO Data

2016 ◽  
Vol 29 (3) ◽  
pp. 1219-1230 ◽  
Author(s):  
Yunying Li ◽  
Minghua Zhang
Keyword(s):  
Tibetan Plateau ◽  
Climate Models ◽  
Surface Wind ◽  
Lower Atmosphere ◽  
The Tibetan Plateau ◽  
Shallow Convection ◽  
Free Atmosphere ◽  
Northern Summer ◽  
Static Energy ◽  
Fine Resolution

Abstract Cumulus (Cu) can transport heat and water vapor from the boundary layer to the free atmosphere, leading to the redistribution of heat and moist energy in the lower atmosphere. This paper uses the fine-resolution CloudSat–CALIPSO product to characterize Cu over the Tibetan Plateau (TP). It is found that Cu is one of the dominant cloud types over the TP in the northern summer. The Cu event frequency, defined as Cu occurring within 50-km segments, is 54% over the TP in the summer, which is much larger over the TP than in its surrounding regions. The surface wind vector converging at the central TP and the topographic forcing provide the necessary moisture and dynamical lifting of convection over the TP. The structure of the atmospheric moist static energy shows that the thermodynamical environment over the northern TP can be characterized as having weak instability, a shallow layer of instability, and lower altitudes for the level of free convection. The diurnal variation of Cu with frequency peaks during the daytime confirms the surface thermodynamic control on Cu formation over the TP. This study offers insights into how surface heat is transported to the free troposphere over the TP and provides an observational test of climate models in simulating shallow convection over the TP.

scholarly journals Uncertainty and Variation of Remotely Sensed Lake Ice Phenology across the Tibetan Plateau

2018 ◽  
Vol 10 (10) ◽  
pp. 1534 ◽  
Author(s):  
Linan Guo ◽  
Yanhong Wu ◽  
Hongxing Zheng ◽  
Bing Zhang ◽  
Junsheng Li ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Land Surface ◽  
Regional Climate ◽  
Local Environment ◽  
Remotely Sensed ◽  
The Tibetan Plateau ◽  
Remotely Sensed Data ◽  
Lake Ice ◽  
Reflectance Data ◽  
Ice Phenology

In the Tibetan Plateau (TP), the changes of lake ice phenology not only reflect regional climate change, but also impose substantial ecohydrological impacts on the local environment. Due to the limitation of ground observation, remote sensing has been used as an alternative tool to investigate recent changes of lake ice phenology. However, uncertainties exist in the remotely sensed lake ice phenology owing to both the data and methods used. In this paper, three different remotely sensed datasets are used to investigate the lake ice phenology variation in the past decade across the Tibetan Plateau, with the consideration of the underlying uncertainties. The remotely sensed data used include reflectance data, snow product, and land surface temperature (LST) data of moderate resolution imaging spectroradiometer (MODIS). The uncertainties of the three methods based on the corresponding data are assessed using the triple collocation approach. Comparatively, it is found that the method based on reflectance data outperforms the other two methods. The three methods are more consistent in determining the thawing dates rather than the freezing dates of lake ice. It is consistently shown by the three methods that the ice-covering duration in the northern part of the TP lasts longer than that in the south. Though there is no general trend of lake ice phenology across the TP for the period of 2000–2015, the warmer climate and stronger wind have led to the earlier break-up of lake ice.

scholarly journals Understanding precipitation recycling over the Tibetan Plateau using tracer analysis with WRF

2020 ◽  
Vol 55 (9-10) ◽  
pp. 2921-2937
Author(s):  
Yanhong Gao ◽  
Fei Chen ◽  
Gonzalo Miguez-Macho ◽  
Xia Li
Keyword(s):  
Tibetan Plateau ◽  
Land Surface ◽  
Precipitation Amount ◽  
Interaction Strength ◽  
Convective Precipitation ◽  
High Mountain ◽  
The Tibetan Plateau ◽  
Important Indicator ◽  
Precipitation Recycling ◽  
Atmosphere Interaction

Abstract The precipitation recycling (PR) ratio is an important indicator that quantifies the land-atmosphere interaction strength in the Earth system’s water cycle. To better understand how the heterogeneous land surface in the Tibetan Plateau (TP) contributes to precipitation, we used the water-vapor tracer (WVT) method coupled with the Weather Research and Forecasting (WRF) regional climate model. The goals were to quantify the PR ratio, in terms of annual mean, seasonal variability and diurnal cycle, and to address the relationships of the PR ratio with lake treatments and precipitation amount. Simulations showed that the PR ratio increases from 0.1 in winter to 0.4 in summer when averaged over the TP with the maxima centered at the headwaters of three major rivers (Yangtze, Yellow and Mekong). For the central TP, the highest PR ratio rose to over 0.8 in August, indicating that most of the precipitation was recycled via local evapotranspiration in summer. The larger daily mean and standard deviation of the PR ratio in summer suggested a stronger effect of land-atmosphere interactions on precipitation in summer than in winter. Despite the relatively small spatial extent of inland lakes, the treatment of lakes in WRF significantly impacted the calculation of the PR ratio over the TP, and correcting lake temperature substantially improved both precipitation and PR ratio simulations. There was no clear relationship between PR ratio and precipitation amount; however, a significant positive correlation between PR and convective precipitation was revealed. This study is beneficial for the understanding of land-atmosphere interaction over high mountain regions.

scholarly journals Land-surface processes and summer-cloud-precipitation characteristics in the Tibetan Plateau and their effects on downstream weather: a review and perspective

2020 ◽  
Vol 7 (3) ◽  
pp. 500-515 ◽  
Author(s):  
Yunfei Fu ◽  
Yaoming Ma ◽  
Lei Zhong ◽  
Yuanjian Yang ◽  
Xueliang Guo ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Tibetan Plateau ◽  
Land Surface ◽  
Sensible Heat Flux ◽  
Vertical Direction ◽  
Heat Fluxes ◽  
Surface Processes ◽  
Convective Precipitation ◽  
The Tibetan Plateau ◽  
Land Surface Processes

Abstract Correct understanding of the land-surface processes and cloud-precipitation processes in the Tibetan Plateau (TP) is an important prerequisite for the study and forecast of the downstream activities of weather systems and one of the key points for understanding the global atmospheric movement. In order to show the achievements that have been made, this paper reviews the progress on the observations for the atmospheric boundary layer, land-surface heat fluxes, cloud-precipitation distributions and vertical structures by using ground- and space-based multiplatform, multisensor instruments and the effect of the cloud system in the TP on the downstream weather. The results show that the form drag related to the topography, land–atmosphere momentum and scalar fluxes is an important part of the parameterization process. The sensible heat flux decreased especially in the central and northern TP caused by the decrease in wind speeds and the differences in the ground-air temperatures. Observations show that the cloud and precipitation over the TP have a strong diurnal variation. Studies also show the compressed-air column in the troposphere by the higher-altitude terrain of the TP makes particles inside clouds vary at a shorter distance in the vertical direction than those in the non-plateau area so that precipitation intensity over the TP is usually small with short duration, and the vertical structure of the convective precipitation over the TP is obviously different from that in other regions. In addition, the influence of the TP on severe weather downstream is preliminarily understood from the mechanism. It is necessary to use model simulations and observation techniques to reveal the difference between cloud precipitation in the TP and non-plateau areas in order to understand the cloud microphysical parameters over the TP and the processes of the land boundary layer affecting cloud, precipitation and weather in the downstream regions.

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