The characteristics of the sensible heat and momentum transfer coefficients over the Gobi in Northwest China

Zhang, Qiang; Barlage, Michael; Tian, Wenshou; Huang, Ronghui

doi:10.1002/joc.2071

Cited by 4 publications

(5 citation statements)

References 11 publications

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“…The neutral bulk transfer coefficient for heat C HN can be related to the roughness length scales for heat ( z oh ) and momentum ( z om ) via [ Zhang et al ., ]:

C_{HN} = \frac{κ^{2}}{\ln true(\frac{z_{ref}}{z_{om}} true) \ln true(\frac{z_{ref}}{z_{oh}} true)},

where κ ≈ 0.4 is the von Karman constant and z ref is the height of micrometeorological measurement.…”

Section: Strong‐constraint Vda Resultsmentioning

confidence: 99%

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Mapping evaporation and estimation of surface control of evaporation using remotely sensed land surface temperature from a constellation of satellites

Bateni

Entekhabi

Castelli

2013

Water Resources Research

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[1] A variational data assimilation model is developed to estimate surface energy fluxes from remotely sensed land surface temperature (LST). Components of the surface energy balance (sensible, latent, and ground heat fluxes) have different degrees of efficiency in dissipating available energy. LST is the state variable of the surface energy balance (SEB). Land surface models that capture the exchange and storage of energy in the soil and vegetation media use LST as a prognostic variable. Sequences of LST measurements implicitly contain information on partitioning of available energy among the components of SEB. In this study, we focus on the estimation of the sum of the turbulent fluxes as well as the partitioning among them. Two dimensionless parameters are used to characterize the sum and the partitioning. Using LST observations from a constellation of satellites, these parameters are mapped over a large region. The remotely sensed LST is assimilated to the heat diffusion equation within the SEB framework. In addition, a model error term is added to the SEB equation such that the variational data assimilation scheme includes model uncertainty as well as observation error. The framework is tested over the Southern Great Plains region. The mapped results of the surface evaporation estimation are used to study the surface control on evaporation. Independent mapped soil moisture estimates from an airborne microwave campaign are used. The dependence of the evaporation control-soil moisture relationship on vegetation cover and plant functional types over large regions is examined in this first and exploratory study.Citation: Bateni, S. M., D. Entekhabi, and F. Castelli (2013), Mapping evaporation and estimation of surface control of evaporation using remotely sensed land surface temperature from a constellation of satellites, Water Resour. Res., 49,

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“…The neutral bulk transfer coefficient for heat C HN can be related to the roughness length scales for heat ( z oh ) and momentum ( z om ) via [ Zhang et al ., ]:

C_{HN} = \frac{κ^{2}}{\ln true(\frac{z_{ref}}{z_{om}} true) \ln true(\frac{z_{ref}}{z_{oh}} true)},

where κ ≈ 0.4 is the von Karman constant and z ref is the height of micrometeorological measurement.…”

Section: Strong‐constraint Vda Resultsmentioning

confidence: 99%

“…The roughness length scales for heat and momentum are themselves related through κB −1 =ln ( z om / z oh ), where B is the Stanton number [ Brutsaert , ; Yang and Friedl , ; Zhang et al ., ]. Brutsaert [] and Duynkerke [] showed the dependence of κB −1 on LAI and friction velocity.…”

Section: Strong‐constraint Vda Resultsmentioning

confidence: 99%

Mapping evaporation and estimation of surface control of evaporation using remotely sensed land surface temperature from a constellation of satellites

Bateni

Entekhabi

Castelli

2013

Water Resources Research

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“…It combines the aerodynamic method with the energy balance method and determines the turbulent fluxes in the surface layer by using the universal functions of the M‐O similarities and the surface‐energy balance equation. Previous studies have evaluated this method and indicated that it is feasible in the Northwest China (Hu & Qi, ; Ma & Ma, , ; Zhang et al, ), where there are few observation sites. The H and ET determined by the combinatory method, which calculates the turbulent flux using the surface layer gradient measurements, were treated as the actual values and were used for the validation of the model estimations.…”

Section: Model Descriptionmentioning

confidence: 99%

Comparison of Two Satellite‐Based Evapotranspiration Models of the Nagqu River Basin of the Tibetan Plateau

Zou

Zhong

et al. 2018

JGR Atmospheres

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Evapotranspiration (ET) is one of the major uncertain components of the energy and water cycle and was derived for the Nagqu River Basin based on remote sensing data and atmospheric surface layer observations under cloudless conditions. Two process‐based models were used to determine the ET: a Priestley‐Taylor (PT)‐based model and a topographical enhanced surface energy balance system (TESEBS) model. Improved broadband albedo, downward shortwave radiation flux, and reconstructed normalized difference vegetation index (NDVI) were coupled into the TESEBS model and PT‐based model to estimate the actual ET. The atmospheric surface layer meteorological data, SPOT Vegetation (VGT) data, and Moderate Resolution Imaging Spectroradiometer data were used as inputs for 10‐day ET calculations. The model‐estimated results were compared with ground truths calculated via the combinatory method. The results indicated that the ET determined by both models well fit the actual ET, with correlation coefficients (R) of 0.88 and 0.82, respectively. However, the TESEBS model showed a better performance than the PT model, with a lower mean bias error (−0.02 mm/hr) and lower root–mean‐square error (0.08 mm/hr). Although the PT model is computationally simple and requires few parameters, the strong weighting of the NDVI may lead to some overestimations, especially during the growing season.

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“…The bulk heat transfer coefficient (C H ) can be written as the product of the neutral bulk heat transfer coefficient (C HN ) and a correction function for atmospheric stability, f(Ri) (i.e., C H = C HN f(Ri), where Ri is the Richardson number). C HN can be related to roughness length scales for heat and momentum [Liu et al, 2007b;Zhang et al, 2010], which is mainly a function of vegetation phenology and is assumed to vary on a monthly temporal scale [McNaughton and Van den Hurk, 1995;Jensen and Hummelshøj, 1995;Qualls and Brutsaert, 1996;Crow and Kustas, 2005;Bateni et al, 2013b]. It scales the sum of turbulent heat fluxes (H + LE) and constitutes the first unknown parameter of the CS scheme.…”

Section: Surface Energy Balance (Seb)mentioning

confidence: 99%

Estimation of surface turbulent heat fluxes via variational assimilation of sequences of land surface temperatures from Geostationary Operational Environmental Satellites

Bateni

Liang

et al. 2014

J. Geophys. Res. Atmos.

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Recently, a number of studies have focused on estimating surface turbulent heat fluxes via assimilation of sequences of land surface temperature (LST) observations into variational data assimilation (VDA) schemes. Using the full heat diffusion equation as a constraint, the surface energy balance equation can be solved via assimilation of sequences of LST within a VDA framework. However, the VDA methods have been tested only in limited field sites that span only a few climate and land use types. Hence, in this study, combined-source (CS) and dual-source (DS) VDA schemes are tested extensively over six FluxNet sites with different vegetation covers (grassland, cropland, and forest) and climate conditions. The CS model groups the soil and canopy together as a single source and does not consider their different contributions to the total turbulent heat fluxes, while the DS model considers them to be different sources. LST data retrieved from the Geostationary Operational Environmental Satellites are assimilated into these two VDA schemes. Sensible and latent heat flux estimates from the CS and DS models are compared with the corresponding measurements from flux tower stations. The results indicate that the performance of both models at dry, lightly vegetated sites is better than that at wet, densely vegetated sites. Additionally, the DS model outperforms the CS model at all sites, implying that the DS scheme is more reliable and can characterize the underlying physics of the problem better.

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The characteristics of the sensible heat and momentum transfer coefficients over the Gobi in Northwest China

Cited by 4 publications

References 11 publications

Mapping evaporation and estimation of surface control of evaporation using remotely sensed land surface temperature from a constellation of satellites

Mapping evaporation and estimation of surface control of evaporation using remotely sensed land surface temperature from a constellation of satellites

Comparison of Two Satellite‐Based Evapotranspiration Models of the Nagqu River Basin of the Tibetan Plateau

Estimation of surface turbulent heat fluxes via variational assimilation of sequences of land surface temperatures from Geostationary Operational Environmental Satellites

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