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Two Improvements of an Operational Two-Layer Model for Terrestrial Surface Heat Flux Retrieval

In order to make the prediction of land surface heat fluxes more robust, two improvements were made to an operational two-layer model proposed previously by Zhang. These improvements are: 1) a surface energy balance method is used to determine the theoretical boundary lines (namely ‘true wet/cool ed...

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Autores principales: Zhang, Renhua, Tian, Jing, Su, Hongbo, Sun, Xiaomin, Chen, Shaohui, Xia, Jun
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Molecular Diversity Preservation International (MDPI) 2008
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3707444/
https://www.ncbi.nlm.nih.gov/pubmed/27873864
http://dx.doi.org/10.3390/s8106165
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author Zhang, Renhua
Tian, Jing
Su, Hongbo
Sun, Xiaomin
Chen, Shaohui
Xia, Jun
author_facet Zhang, Renhua
Tian, Jing
Su, Hongbo
Sun, Xiaomin
Chen, Shaohui
Xia, Jun
author_sort Zhang, Renhua
collection PubMed
description In order to make the prediction of land surface heat fluxes more robust, two improvements were made to an operational two-layer model proposed previously by Zhang. These improvements are: 1) a surface energy balance method is used to determine the theoretical boundary lines (namely ‘true wet/cool edge’ and ‘true dry/warm edge’ in the trapezoid) in the scatter plot for the surface temperature versus the fractional vegetation cover in mixed pixels; 2) a new assumption that the slope of the T(m) – f curves is mainly controlled by soil water content is introduced. The variables required by the improved method include near surface vapor pressure, air temperature, surface resistance, aerodynamic resistance, fractional vegetation cover, surface temperature and net radiation. The model predictions from the improved model were assessed in this study by in situ measurements, which show that the total latent heat flux from the soil and vegetation are in close agreement with the in situ measurement with an RMSE (Root Mean Square Error) ranging from 30 w/m(2)∼50 w/m(2), which is consistent with the site scale measurement of latent heat flux. Because soil evaporation and vegetation transpiration are not measured separately from the field site, in situ measured CO(2) flux is used to examine the modeled λE(veg). Similar trends of seasonal variations of vegetation were found for the canopy transpiration retrievals and in situ CO(2) flux measurements. The above differences are mainly caused by 1) the scale disparity between the field measurement and the MODIS observation; 2) the non-closure problem of the surface energy balance from the surface fluxes observations themselves. The improved method was successfully used to predict the component surface heat fluxes from the soil and vegetation and it provides a promising approach to study the canopy transpiration and the soil evaporation quantitatively during the rapid growing season of winter wheat in northern China.
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spelling pubmed-37074442013-07-10 Two Improvements of an Operational Two-Layer Model for Terrestrial Surface Heat Flux Retrieval Zhang, Renhua Tian, Jing Su, Hongbo Sun, Xiaomin Chen, Shaohui Xia, Jun Sensors (Basel) Article In order to make the prediction of land surface heat fluxes more robust, two improvements were made to an operational two-layer model proposed previously by Zhang. These improvements are: 1) a surface energy balance method is used to determine the theoretical boundary lines (namely ‘true wet/cool edge’ and ‘true dry/warm edge’ in the trapezoid) in the scatter plot for the surface temperature versus the fractional vegetation cover in mixed pixels; 2) a new assumption that the slope of the T(m) – f curves is mainly controlled by soil water content is introduced. The variables required by the improved method include near surface vapor pressure, air temperature, surface resistance, aerodynamic resistance, fractional vegetation cover, surface temperature and net radiation. The model predictions from the improved model were assessed in this study by in situ measurements, which show that the total latent heat flux from the soil and vegetation are in close agreement with the in situ measurement with an RMSE (Root Mean Square Error) ranging from 30 w/m(2)∼50 w/m(2), which is consistent with the site scale measurement of latent heat flux. Because soil evaporation and vegetation transpiration are not measured separately from the field site, in situ measured CO(2) flux is used to examine the modeled λE(veg). Similar trends of seasonal variations of vegetation were found for the canopy transpiration retrievals and in situ CO(2) flux measurements. The above differences are mainly caused by 1) the scale disparity between the field measurement and the MODIS observation; 2) the non-closure problem of the surface energy balance from the surface fluxes observations themselves. The improved method was successfully used to predict the component surface heat fluxes from the soil and vegetation and it provides a promising approach to study the canopy transpiration and the soil evaporation quantitatively during the rapid growing season of winter wheat in northern China. Molecular Diversity Preservation International (MDPI) 2008-10-01 /pmc/articles/PMC3707444/ /pubmed/27873864 http://dx.doi.org/10.3390/s8106165 Text en © 2008 by the authors; licensee Molecular Diversity Preservation International, Basel, Switzerland. This article is an open-access article distributed under the terms and conditions of the CreativeCommons Attribution license (http://creativecommons.org/licenses/by/3.0/).
spellingShingle Article
Zhang, Renhua
Tian, Jing
Su, Hongbo
Sun, Xiaomin
Chen, Shaohui
Xia, Jun
Two Improvements of an Operational Two-Layer Model for Terrestrial Surface Heat Flux Retrieval
title Two Improvements of an Operational Two-Layer Model for Terrestrial Surface Heat Flux Retrieval
title_full Two Improvements of an Operational Two-Layer Model for Terrestrial Surface Heat Flux Retrieval
title_fullStr Two Improvements of an Operational Two-Layer Model for Terrestrial Surface Heat Flux Retrieval
title_full_unstemmed Two Improvements of an Operational Two-Layer Model for Terrestrial Surface Heat Flux Retrieval
title_short Two Improvements of an Operational Two-Layer Model for Terrestrial Surface Heat Flux Retrieval
title_sort two improvements of an operational two-layer model for terrestrial surface heat flux retrieval
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3707444/
https://www.ncbi.nlm.nih.gov/pubmed/27873864
http://dx.doi.org/10.3390/s8106165
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