Estimation of Surface Heat Fluxes Over the Central Tibetan Plateau using the Maximum Entropy Production Model

Li, Na; Zhao, Ping; Wang, Jingfeng; Deng, Yi

doi:10.1029/2018jd029959

Cited by 13 publications

(13 citation statements)

References 80 publications

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“…To analyze the factors affecting the ABL in the TP, we use the TIPEX-III 30-min mean surface sensible heat flux (SHF), downward solar radiation, and 5-cm soil volume moisture content at SQH (bare soil with few obstacles), Naqu (NQ; alpine steppe), and Linzhi (LZ; alpine meadow with few shrubs and trees) stations in the 2014-2015 summers (Wang et al, 2016;Zhao et al, 2018;Li et al, 2019Li et al, , 2020. In addition, the operational observation of total cloudiness (cloud cover) at 02:00 BJT, 08:00 BJT, 14:00 BJT, and 20:00 BJT from the China Meteorological Administration are also used.…”

Section: Data and Analysis Methodsmentioning

confidence: 99%

Characteristics of the summer atmospheric boundary layer height over the Tibetan Plateau and influential factors

Che¹,

Zhao²

2020

Preprint

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Abstract. Based on intensive sounding, surface sensible heat flux, solar radiation, and soil moisture observational datasets from the Third Tibetan Plateau Atmospheric Scientific Experiment and the routine meteorological operational sounding and total cloudiness datasets in the Tibetan Plateau (TP) for the period 2013–2015, we investigate the features of summer atmospheric boundary layer (ABL) over the TP and its major influential factors. It is found that the convective boundary layer (CBL) and the neutral boundary layer (NBL) show remarkable diurnal variations over the TP, while the stable boundary layer (SBL) diurnal variation is weak. In the early morning, the ABL height distribution is narrow, with a small west-east difference. The SBL accounts for 85 % of the TP ABL. At noon, there is a wide distribution in the ABL height up to 4000 m. The CBL accounts for 77 % of the TP ABL, with more than 50 % of the CBL height above 1900 m. The ABL height exhibits a large west-east difference, with a mean height above 2000 m in the western TP and around 1500 m in the eastern TP. In the late afternoon, the CBL and SBL dominate the western and eastern TP, respectively, resulting in a larger west-east difference of 1054.2 m between the western and eastern TP. The high ABL height in a cold environment over the western TP (relative to the plain areas) is similar to that in some extreme hot and arid areas such as Dunhuang and Taklimakan Deserts. For the western (eastern) TP, there is low (high) total cloud coverage, with large (small) solar radiation at the surface and dry (wet) soil. These features result in high (low) sensible heat flux and thus promotes (inhibits) the local ABL development.

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Section: Data and Analysis Methodsmentioning

confidence: 99%

Characteristics of the summer atmospheric boundary layer height over the Tibetan Plateau and influential factors

Che¹,

Zhao²

2020

Preprint

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“…The energy balance ratio, that is, EBR = (SH + LE)/(R n − G), was evaluated to ensure the usability of observations for the study site and period, in which R n is the net radiation and G is the ground heat flux. In the absence of the observed G, it is estimated using the method of Li et al (2019). Our result shows that the mean value of EBR is 0.90 in summers during 2014-2016, thereby indicating the reliability of the TIPEX-III summer surface heat fluxes at the Ali site.…”

Section: Methodsmentioning

confidence: 68%

“…Therefore, the errors in precipitation may lead to a large uncertainty in the reanalysis LE. In addition, the difference in the parameterization of the moisture transfer coefficient, surface roughness lengths, and wind speed may also lead to the conspicuous differences among the six reanalysis LE data [33][34][35].Since the parameterization scheme of the MEP model may be able to reflect the surface humidity condition, the uncertainties of the estimated LE using the MEP model can be substantially reduced compared with the reanalysis LE [20,29]. The LE-merged presents a significant variation from 1980 to 2018.…”

Section: Discussionmentioning

confidence: 99%

“…They were measured by eddy covariance and hereafter referred to as SH EC and LE EC , respectively. Following Li et al (2019), the quality of the half-hourly SH EC and LE EC at the Ali site was controlled. We processed the half-hourly flux observations into daily values.…”

Section: Methodsmentioning

confidence: 99%

“…Besides the LE estimation methods described above, a new approach, the maximum entropy production (MEP) model, has been developed to estimate the surface heat fluxes on bare soil, vegetation, water/snow/ice, and ocean surfaces [19]. The MEP model has been successfully applied to estimate the surface heat fluxes over the alpine steppe terrain of the central TP [20]. However, the MEP model has not yet been applied to estimate LE in the bare soil condition over the western TP.…”

Section: Introductionmentioning

confidence: 99%

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The Long-Term Change of Latent Heat Flux over the Western Tibetan Plateau

Zhao

Wang

et al. 2020

Atmosphere

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The Tibetan Plateau (TP) has been experiencing warming and wetting since the 1980s. Under such circumstances, we estimated the summer latent heat flux (LE) using the maximum entropy production model driven by the net radiation, surface temperature, and soil moisture of three reanalysis datasets (ERA5, JRA-55, and MERRA-2) at the Ali site over the western TP during 1980–2018. Compared with the observed LE of the Third Tibetan Plateau Atmospheric Scientific Experiment, the coefficient of determination, root-mean-square error, and mean bias error of the estimated summer LE are 0.57, 9.3 W m−2, and −2.25 W m−2 during 2014–2016, respectively, which are better than those of LE of the reanalysis datasets. The estimated long-term summer LE presents a decreasing (an increasing) trend of −7.4 (1.8) W m−2 decade−1 during 1980–1991 (1992–2018). The LE variation is closely associated with the local soil moisture influenced by precipitation, glacier, and near-surface water conditions at the Ali site. The summer soil moisture also presents a decreasing (an increasing) trend of −0.082 (0.022) decade−1 during 1980–1991 (1992–2018). The normalized difference vegetation index generally shows the consistent trend with LE at the Ali site.

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Estimations of Land Surface Characteristic Parameters and Turbulent Heat Fluxes over the Tibetan Plateau Based on FY-4A/AGRI Data

Gao

Zhong

et al. 2021

Adv. Atmos. Sci.

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Estimation of Surface Heat Fluxes Over the Central Tibetan Plateau using the Maximum Entropy Production Model

Cited by 13 publications

References 80 publications

Characteristics of the summer atmospheric boundary layer height over the Tibetan Plateau and influential factors

Characteristics of the summer atmospheric boundary layer height over the Tibetan Plateau and influential factors

The Long-Term Change of Latent Heat Flux over the Western Tibetan Plateau

Estimations of Land Surface Characteristic Parameters and Turbulent Heat Fluxes over the Tibetan Plateau Based on FY-4A/AGRI Data

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