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Impacts of Initial Soil Moisture and Vegetation on the Diurnal Temperature Range in Arid and Semiarid Regions in China
Author(s) -
Yuan Guanghui,
Zhang Lei,
Liang Jiening,
Cao Xianjie,
Guo Qi,
Yang Zhaohong
Publication year - 2017
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2017jd026790
Subject(s) - daytime , environmental science , diurnal temperature variation , emissivity , atmospheric sciences , arid , weather research and forecasting model , energy budget , planetary boundary layer , microclimate , water content , diurnal cycle , latent heat , vegetation (pathology) , sensible heat , convective boundary layer , boundary layer , climatology , meteorology , geography , geology , medicine , paleontology , physics , geotechnical engineering , archaeology , pathology , optics , thermodynamics
To assess the impacts of initial soil moisture (SMOIS) and the vegetation fraction (Fg) on the diurnal temperature range (DTR) in arid and semiarid regions in China, three simulations using the weather research and forecasting (WRF) model are conducted by modifying the SMOIS, surface emissivity and Fg. SMOIS affects the daily maximum temperature (Tmax) and daily minimum temperature (Tmin) by altering the distribution of available energy between sensible and latent heat fluxes during the day and by altering the surface emissivity at night. Reduced soil wetness can increase both the Tmax and Tmin, but the effect on the DTR is determined by the relative strength of the effects on Tmax and Tmin. Observational data from the Semi‐Arid Climate and Environment Observatory of Lanzhou University (SACOL) and the Shapotou Desert Research and Experimental Station (SPD) suggest that the magnitude of the SMOIS effect on the distribution of available energy during the day is larger than that on surface emissivity at night. In other words, SMOIS has a negative effect on the DTR. Changes in Fg modify the surface radiation and the energy budget. Due to the depth of the daytime convective boundary layer, the temperature in daytime is affected less than in nighttime by the radiation and energy budget. Increases in surface emissivity and decreases in soil heating resulting from increased Fg mainly decrease Tmin, thereby increasing the DTR. The effects of SMOIS and Fg on both Tmax and Tmin are the same, but the effects on DTR are the opposite.

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