Observed Key Surface Parameters for Characterizing Land–Atmospheric Interactions in the Northern Marginal Zone of the Taklimakan Desert, China

Abstract

An observational data set of the year 2010 at a site in the northern marginal zone of the Taklimakan Desert (TD) was used to analyse the key surface parameters in land–atmospheric interactions in the desert climate of northwest China. We found that the surface albedo (α) and emissivity (ε) were 0.27 and 0.91, respectively, which were consistent with the values obtained based on observations in the hinterland of the TD as well as being similar to the dry parts of the Great Basin desert in North America, where they were comparable to the α and ε values retrieved from remote sensing products. Peak frequency value of z0m was 5.858 × 10−3 m, which was similar to the Mojave Desert, Peruvian desert, Sonoran Desert, HEIFE (Heihe region) Desert, and Badain Jaran Desert. The peak frequency value of z0h was 1.965 × 10−4 m, which was different from those obtained in the hinterland of the TD. The average annual value of excess resistance to heat transfer (kB−1) was 2.5, which was different from those obtained in the HEIFE Gobi and desert, but they were similar to those determined for the Qinghai–Tibetan Plateau and HAPEX-Sahel. Both z0m and z0h varied less diurnally but notably seasonally, and kB−1 exhibited weak diurnal and seasonal variations. We also found that z0m was strongly influenced by the local wind direction. There were many undulating sand dunes in the prevailing wind and opposite to the prevailing wind, which were consistent with the directions of the peak z0m value. The mean values calculated over 24 h for Cd and Ch were 6.34 × 10−3 and 5.96 × 10−3, respectively, which were larger than in the Gobi area, hinterland of the TD and semiarid areas, but similar to HEIFE desert. Under the normal prevailing (NNE–ESE) wind, the mean bulk transfer coefficient Cd and Ch were of the same order of magnitude as expected based on similarity theory. Using the data obtained under different wind directions, we determined the relationships between Cd, Ch, the wind speed U, and stability parameter z/L, and the results were different. Cd and Ch decreased rapidly as the wind speed dropped below 3.0 m s−1 and their minimum values reached around 1–2 m s−1. It should also be noted that the ε values estimated using the sensible heat flux (H) were better compared with those produced using other estimation methods.