Relating Precipitating Ice Radiative Effects to Surface Energy Balance and Temperature Biases Over the Tibetan Plateau in Winter

2019 ◽  
Vol 124 (23) ◽  
pp. 12455-12467
Author(s):  
Wei‐Liang Lee ◽  
Jui‐Lin Frank Li ◽  
Kuan‐Man Xu ◽  
Ettamal Suhas ◽  
Jonathan H. Jiang ◽  
...  
Keyword(s):  
Energy Balance ◽  
Tibetan Plateau ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
The Tibetan Plateau ◽  
Radiative Effects

scholarly journals High-resolution modelling of interactions between soil moisture and convection development in mountain enclosed Tibetan basin

2015 ◽  
Vol 12 (5) ◽  
pp. 4631-4675
Author(s):  
T. Gerken ◽  
W. Babel ◽  
M. Herzog ◽  
K. Fuchs ◽  
F. Sun ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Energy Balance ◽  
Tibetan Plateau ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Local Development ◽  
Lake Basin ◽  
Strong Impact ◽  
The Tibetan Plateau ◽  
Moist Convection

Abstract. The Tibetan Plateau plays a significant role in the atmospheric circulation and the Asian monsoon system. Turbulent surface fluxes and the evolution of boundary layer clouds to deep and moist convection provide a feedback system that modifies the Plateau's surface energy balance on scales that are currently unresolved in mesoscale models. This work analyses the land surface's role and specifically the influence of soil moisture on the triggering of convection at a cross-section of the Nam Co Lake basin, 150 km north of Lhasa using a cloud resolving atmospheric model with a fully coupled surface. The modelled turbulent fluxes and development of convection compare reasonably well with the observed weather. The simulations span Bowen-ratios of 0.5 to 2.5. It is found that convection development is strongest at intermediate soil moistures. Dry cases with soils close to the permanent wilting point are moisture limited in the convection development, while convection in wet soil moisture cases is limited by cloud cover reducing incoming solar radiation and sensible heat fluxes. This has a strong impact on the surface energy balance. This study also shows that local development of convection is an important mechanism for the upward transport of water vapour that originates from the lake basin that can then be transported to dryer regions of the plateau. Both processes demonstrate the importance of soil moisture and surface–atmosphere interactions on the energy and hydrological cycles of the Tibetan Plateau.

The impact of the Westerlies on the PBL growth and land surface energy balance on the north of the central Himalaya

2020 ◽  
Author(s):  
Xuelong Chen ◽  
Yue Lai ◽  
Yaoming Ma
Keyword(s):  
Energy Balance ◽  
Tibetan Plateau ◽  
Surface Energy ◽  
Land Surface ◽  
Surface Energy Balance ◽  
The Tibetan Plateau ◽  
Central Himalaya ◽  
Mountainous Areas ◽  
The North ◽  
The Impact

<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.<br>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. This study used radiosonde, in-situ measurements and ECMWF ERA5 reanalysis dataset 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. Measurements show that the altitude of the PBL’s top in November was the highest of three intensive observation periods (i.e., June, August and November). The PBLs in November appeared to have been influenced by the Westerlies which prevails in this region during the non-monsoon season. We discovered that the deep PBLs seen in November correlate with the downward transmission of the Westerlies to the valley floor (DTWTV). It was found that DTWTV happened in the direction of southwest when the synoptic wind above the valley ridges height blow from southwest, which is parallel to the valley axis. DTWTV happened in the direction of southwest promotes a stronger near-surface wind, smaller aerodynamic resistance, and larger sensible heat flux, which cause PBLs grow high.</p>

scholarly journals High-resolution modelling of interactions between soil moisture and convective development in a mountain enclosed Tibetan Basin

2015 ◽  
Vol 19 (9) ◽  
pp. 4023-4040 ◽  
Author(s):  
T. Gerken ◽  
W. Babel ◽  
M. Herzog ◽  
K. Fuchs ◽  
F. Sun ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Energy Balance ◽  
Tibetan Plateau ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Local Development ◽  
Lake Basin ◽  
Strong Impact ◽  
The Tibetan Plateau ◽  
Moist Convection

Abstract. The Tibetan Plateau plays a significant role in atmospheric circulation and the Asian monsoon system. Turbulent surface fluxes and the evolution of boundary-layer clouds to deep and moist convection provide a feedback system that modifies the plateau's surface energy balance on scales that are currently unresolved in mesoscale models. This work analyses the land surface's role and specifically the influence of soil moisture on the triggering of convection at a cross section of the Nam Co Lake basin, 150 km north of Lhasa using a cloud-resolving atmospheric model with a fully coupled surface. The modelled turbulent fluxes and development of convection compare reasonably well with the observed weather. The simulations span Bowen ratios of 0.5 to 2.5. It is found that convective development is the strongest at intermediate soil moisture. Dry cases with soils close to the permanent wilting point are moisture limited in convective development, while convection in wet soil moisture cases is limited by cloud cover reducing incoming solar radiation and sensible heat fluxes, which has a strong impact on the surface energy balance. This study also shows that local development of convection is an important mechanism for the upward transport of water vapour, which originates from the lake basin that can then be transported to dryer regions of the plateau. Both processes demonstrate the importance of soil moisture and surface–atmosphere interactions on the energy and hydrological cycles of the Tibetan Plateau.

An Improvement of Roughness Height Parameterization of the Surface Energy Balance System (SEBS) over the Tibetan Plateau

2013 ◽  
Vol 52 (3) ◽  
pp. 607-622 ◽  
Author(s):  
Xuelong Chen ◽  
Zhongbo Su ◽  
Yaoming Ma ◽  
Kun Yang ◽  
Jun Wen ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Balance ◽  
Tibetan Plateau ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Bare Soil ◽  
Roughness Height ◽  
The Tibetan Plateau ◽  
Sensible Heat ◽  
Balance System

AbstractRoughness height for heat transfer is a crucial parameter in the estimation of sensible heat flux. In this study, the performance of the Surface Energy Balance System (SEBS) has been tested and evaluated for typical land surfaces on the Tibetan Plateau on the basis of time series of observations at four sites with bare soil, sparse canopy, dense canopy, and snow surface, respectively. Both under- and overestimation at low and high sensible heat fluxes by SEBS was discovered. Through sensitivity analyses, it was identified that these biases are related to the SEBS parameterization of bare soil’s excess resistance to heat transfer (kB−1, where k is the von Kármán constant and B−1 is the Stanton number). The kB−1 of bare soil in SEBS was replaced. The results show that the revised model performs better than the original model.

scholarly journals Surface energy balance closure at ten sites over the Tibetan plateau

2018 ◽  
Vol 259 ◽  
pp. 317-328 ◽  
Author(s):  
Yu-Fei Xin ◽  
Fei Chen ◽  
Ping Zhao ◽  
Michael Barlage ◽  
Peter Blanken ◽  
...  
Keyword(s):  
Energy Balance ◽  
Tibetan Plateau ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
The Tibetan Plateau ◽  
Energy Balance Closure

scholarly journals Evapotranspiration Estimation Using Surface Energy Balance System Model: A Case Study in the Nagqu River Basin

Atmosphere ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 268 ◽  
Author(s):  
Lei Zhong ◽  
Kepiao Xu ◽  
Yaoming Ma ◽  
Ziyu Huang ◽  
Xian Wang ◽  
...  
Keyword(s):  
Energy Balance ◽  
Tibetan Plateau ◽  
Surface Energy ◽  
River Basin ◽  
Land Surface ◽  
Surface Energy Balance ◽  
Hydrological Cycle ◽  
The Tibetan Plateau ◽  
Balance System ◽  
Northern Tibetan Plateau

Calculation of actual evapotranspiration (AET) is of vital importance for the study of climate change, ecosystem carbon cycling, flooding, drought, and agricultural water demand. It is one of the more important components in the hydrological cycle and surface energy balance (SEB). How to accurately estimate AET especially for the Tibetan Plateau (TP) with complex terrain remains a challenge for the scientific community. Using multi-sensor remote sensing data, meteorological forcing data, and field observations, AET was derived for the Nagqu river basin of the Northern Tibetan Plateau from a surface energy balance system (SEBS) model. As inputs for SEBS, improved algorithms and datasets for land surface albedo and a cloud-free normalized difference vegetation index (NDVI) were also constructed. The model-estimated AET were compared with results by using the combinatory method (CM). The validation indicated that the model estimates of AET agreed well with the correlation coefficient, the root mean square error, and the mean percentage error of 0.972, 0.052 mm/h, and −10.4%, respectively. The comparison between SEBS estimation and CM results also proved the feasibility of parameterization schemes for land surface parameters and AET.

scholarly journals Diurnal and Seasonal Variations of Surface Energy and CO2 Fluxes over a Site in Western Tibetan Plateau

Atmosphere ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 260 ◽  
Author(s):  
Xingbing Zhao ◽  
Changwei Liu ◽  
Nan Yang ◽  
Yubin Li
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Tibetan Plateau ◽  
Surface Energy ◽  
Seasonal Variations ◽  
Surface Energy Balance ◽  
Diurnal Variations ◽  
Heat Fluxes ◽  
Co2 Fluxes ◽  
Western Tibetan Plateau

Land surface process observations in the western Tibet Plateau (TP) are limited because of the abominable natural conditions. During the field campaign of the Third Tibetan Plateau Atmospheric Scientific Experiment (TIPEX III), continuous measurements on the four radiation fluxes (downward/upward short/long-wave radiations), three heat fluxes (turbulent sensible/latent heat fluxes and soil heat flux) and also CO2 flux were collected from June 2015 through January 2017 at Shiquanhe (32.50° N, 80.08° E, 4279.3 m above sea level) in the western Tibetan Plateau. Diurnal and seasonal variation characteristics of these surface energy and CO2 fluxes were presented and analyzed in this study. Results show that (1) diurnal variations of the seven energy fluxes were found with different magnitudes, (2) seasonal variations appeared for the seven energy fluxes with their maxima in summer and minima in winter, (3) diurnal and seasonal variations of respiration caused by the biological and chemical processes within the soil were found, and absorption (release) of CO2 around 0.1 mg m−2 s−1 occurred at afternoon of summer (midnight of winter), but the absorption and release generally canceled out from a yearly perspective; and (4) the surface energy balance ratio went through both diurnal and seasonal cycles, and in summer months the slopes of the fitting curve were above 0.6, but in winter months they were around 0.5. Comparing the results of the Shiquanhe site with the central and eastern TP sites, it was found that (1) they all generally had similar seasonal and diurnal variations of the fluxes, (2) caused by the low rainfall quantity, latent heat flux at Shiquanhe (daily daytime mean always less than 90 W m−2) was distinctively smaller than at the central and eastern TP sites during the wet season (generally larger than 100 W m−2), and (3) affected by various factors, the residual energy was comparatively larger at Shiquanhe, which led to a small surface energy balance ratio.

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