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A study of variation characteristics of Gobi broadband emissivity based on field observational experiments in northwestern China

Journal

Theoretical and Applied Climatology

Authors

Zhi-yuan Zheng,Zhi-gangWei,Zhi-ping Wen,Wen-jie Dong,Zhen-chao Li,Xiao-hang Wen,Xian Zhu,Chen Chen,Shan-shan Hu

Year

2018

Volume

131

Issue

43163

Pages

1357-1368

Corresponding Author

Wei, ZG

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wzg@bnu.edu.cn

Keywords

Northwestern China; Arid and semiarid areas; Field observational experiments; Typical bare soil underlying surface; Gobi broadband emissivity

Abstract

Land surface emissivity is a significant variable in energy budgets, land cover assessments, and environment and climate studies. However, the assumption of an emissivity constant is being used in Gobi broadband emissivity (GbBE) parameterization scheme in numerical models because of limited knowledge surrounding the spatiotemporal variation characteristics of GbBE. To address this issue, we analyzed the variation characteristics of GbBE and possible impact factor-surface soil moisture based on long-term continuous and high temporal resolution field observational experiments over a typical Gobi underlying surface in arid and semiarid areas in northwestern China. The results indicate that GbBE has obvious daily and diurnal variation features, especially diurnal cycle characteristics. The multi-year average of the daily average of GbBE is in the range of 0.932 to 0.970 with an average of 0.951 +/- 0.008, and the average diurnal GbBE is in the range of 0.880 to 0.940 with an average of 0.906 +/- 0.018. GbBE varies with surface soil moisture content. We observed a slight decrease in GbBE with an increase in soil moisture, although this change was not very obvious because of the low soil moisture in this area. Nevertheless, we think that soil moisture must be one of the most significant impact factors on GbBE in arid and semiarid areas. Soil moisture must be taken into account into the parameterization schemes of bare soil broadband emissivity in land surface models. Additional field experiments and studies should be carried out in order to clarify this issue.
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