The bulk transfer coefficients and surface fluxes on the western Tibetan Plateau

Li, Guoping; Tingyang, Duan; Gong, Yuanfa

doi:10.1007/bf02886084

Cited by 25 publications

(20 citation statements)

References 5 publications

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“…For the drag coefficient selection, Yeh et al [3] proposed a value of 8×10 3 , but many studies [29][30][31] have shown that a mean value C DH =4×10 3 is more reasonable for the CE-TP. Li et al [31,32] calculated drag coefficients on the eastern and western plateau, finding a C DH range from 3.3×10 3 to 4.4×10 3 on the eastern plateau, we therefore selected an average value of 4×10 3 .…”

Section: Methodsmentioning

confidence: 99%

Trend in the atmospheric heat source over the central and eastern Tibetan Plateau during recent decades: Comparison of observations and reanalysis data

2011

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The trend in the atmospheric heat source over the central and eastern Tibetan Plateau (CE-TP) is quantitatively estimated using historical observations at 71 meteorological stations, three reanalysis datasets from 1980-2008, and two satellite radiation datasets from . Results show that a weakening of sensible heat (SH) flux over the CE-TP continues. The most significant trend occurs in spring, induced mainly by decelerated surface wind speeds. The ground-air temperature difference shows a notable increasing trend over the last 5 years. Trends in net radiation flux of the atmospheric column over the CE-TP, evaluated by two satellite radiation datasets, are clearly different. Trends in the atmospheric heat source calculated by the three reanalysis datasets are not completely consistent, and even show opposite signals. Results from the two datasets both show a weakening of the heat source but the magnitude of one is significantly stronger, whereas an increase is indicated by the other data. Therefore, it is challenging to accurately calculate the trend in the atmospheric heat source over the CE-TP, particularly from the estimates of the reanalysis datasets. The Tibetan Plateau (TP) is situated on the subtropical eastcentral Eurasian continent. It is the highest (average elevation > 4000 m) plateau in the world, with complex topography and surface conditions. As a strong heat source, the plateau directly heats the middle troposphere [1][2][3]. In spring, sensible heat (SH) dominates the atmospheric heat source over the TP and works efficiently as a huge air pump [4], for not only the onset and maintenance of the Asian summer monsoon [5], but also for the development of weather systems over east China [6] and even the boreal summer climate pattern [6,7]. Changes in the thermal condition of the TP and the atmospheric circulation in East Asia are closely related [8]. Zhao and Chen [9] investigated the atmospheric heat source over the TP and its relationship with rainfall in China, and concluded that this heat source in spring may be regarded as a good indicator of a summer precipitation anomaly in east China. They also showed that it had a clear positive correlation with summer precipitation in the middle and lower reaches of the Yangtze River. Bai et al.[10] confirmed these results. Duan and Wu [11] pointed out that it is not adequate to study the influence of TP thermal forcing on the climate with an area-averaged heating index, because of the large area and various climate types of the TP. Under a global warming scenario, TP warming is powerful, and the warming trend is much greater than surrounding regions at the same latitudes [12][13][14][15]. The thermal condition of the TP is an important influence on atmospheric circulation, climate change and long-term weather processes. The relationship between TP heating and variability

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Section: Methodsmentioning

confidence: 99%

Trend in the atmospheric heat source over the central and eastern Tibetan Plateau during recent decades: Comparison of observations and reanalysis data

2011

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“…Previous studies show that the hydrothermal variations in the active layer affect the hydrology and ecosystem in the region [11][12][13][14][15]. Studies of the active layer and permafrost on the QTP have received much recent attention [16][17][18][19][20]. Recent work in the area has shown that, due to global climate warming, the permafrost on the QTP has degraded remarkably, including a rise in permafrost temperature, an increase in the thickness of the active layer, and a decrease in permafrost area [21][22][23][24].…”

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confidence: 99%

Temporal and spatial variations of the active layer along the Qinghai-Tibet Highway in a permafrost region

et al. 2012

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“…Afterward, Chen et al (1985) obtained a smaller value of 4×10 -3 by using this parameterized scheme. On the basis of data from two (four) sets of automatic weather stations over the western (central and eastern) TP from July 1993 to March 1999, Li et al (2000Li et al ( , 2001) estimated the C DH value by using the flux-profile relationship, with results of 6-6.4 × 10 -3 at the western TP and 4.8 × 10 -3 at the central and eastern TP. Recently, Yang et al (2011b) discussed the differences between methods for estimating the trend in SHF over the TP for the period 1984-2006.…”

Section: Uncertainties In Shf and Lh Based On Station Distributionmentioning

confidence: 99%

Uncertainties in Quantitatively Estimating the Atmospheric Heat Source over the Tibetan Plateau

Duan

Wang

Xiao

2014

Atmospheric and Oceanic Science Letters

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As a huge, intense, and elevated atmospheric heat source (AHS) approaching the mid-troposphere in spring and summer, the Tibetan Plateau (TP) thermal forcing is perceived as an important factor contributing to the formation and variation of the Asian summer monsoon. Despite numerous studies devoted to determine the strength and change of the thermal forcing of the TP on the basis of various data sources and methods, uncertainties remain in quantitative estimation of the AHS and will persist for the following reasons: (1) Routine meteorological stations cover only limited regions and show remarkable spatial inhomogeneity with most distributed in the central and eastern plateau. Moreover, all of these stations are situated at an altitude below 5000 m. Thus, the large area above that elevation is not included in the data. (2) Direct observations on heat fluxes do not exist at most stations, and the sensible heat flux (SHF) is calculated by the bulk formula, in which the drag coefficient for heat is often treated as an empirical constant without considering atmospheric stability and thermal roughness length. (3) Radiation flux derived by satellite remote sensing shows a large discrepancy in the algorithm in data inversion and complex terrain. (4) In reanalysis data, besides the rare observational records employed for data assimilation, model bias in physical processes induces visible errors in producing the diabatic heating fields.  Keywords: Tibetan Plateau, atmospheric heat source, data bias, uncertainties Citation: Duan, A.-M., M. R., Wang, and Z.-X. Xiao, 2014: Uncertainties in quantitatively estimating the atmospheric heat source over the Tibetan Plateau, Atmos.

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The bulk transfer coefficients and surface fluxes on the western Tibetan Plateau

Cited by 25 publications

References 5 publications

Trend in the atmospheric heat source over the central and eastern Tibetan Plateau during recent decades: Comparison of observations and reanalysis data

Trend in the atmospheric heat source over the central and eastern Tibetan Plateau during recent decades: Comparison of observations and reanalysis data

Temporal and spatial variations of the active layer along the Qinghai-Tibet Highway in a permafrost region

Uncertainties in Quantitatively Estimating the Atmospheric Heat Source over the Tibetan Plateau

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