Abstract
As the largest fixed and semifixed desert in China, the Gurbantünggüt Desert has a longperiod of snow in winter and the rapid growth of ephemeral plants in spring, presentingthe obvious seasonal changes in the underlying desert surface type, which could lead to the significantvariety in the near-surface boundary layer over this desert. To clarify the influence of the underlying surface change on the near-surface atmospheric boundary layer, gradient tower data and Eddy covariance data in 2017 were analyzed. The results were as follows: the wind profile can be divided into the nocturnal stable boundary layer and the daytime unstable boundary in spring, summer, and autumn, while the wind profile dominating nighttime stability in winter. During the study period, the four-season temperature profiles can be divided into four types: night radiation type, morning transition type, daylight solar radiation type, and evening transition type, and the temperature difference between spring and summer is more than that of autumn and winter. The vertical temperature lapse rate can reach 4.5°C/100 m in spring and summer, while the vertical temperature lapse rate is 0.5°C/100 m in winter. The special humidity value in summer and spring is greater than autumn and winter. The profile is almost in the inverse humidity state at almost all periods in winter. The inverse humidity phenomenon occurred on the autumn night. Besides, the specific humidity is closely related to the temperature and the near-surface wind speed. The “rapid change” of the underlying surface of the spring desert region affects the surface energy budget, which affects the turbulent energy and the stability of the near-surface layer, thus affecting the changes in temperature, humidity, and wind profile.
Highlights
As the largest fixed and semifixed desert in China, the Gurbantunggut Desert has a longperiod of snow in winter and the rapid growth of ephemeral plants in spring, presentingthe obvious seasonal changes in the underlying desert surface type, which could lead to the significantvariety in the near-surface boundary layer over this desert
Compared to the majority of the world’s surface types, the desert covers the extensive spatial areas and has distinctly different surface properties. erefore, deserts have a large influence on the climate and atmospheric circulation [2]. e desert areas have high surface temperatures, few clouds, dry surfaces, and high sensible heat fluxes, so the desert boundary layer is usually thicker [3]. e Gurbantunggut Desert is the only desert in China where snow exists for a long time during the winter, and there is short-lived vegetation during the spring [4, 5]. is unique desert environment is especially sensitive to climate changes, it follows a specific pattern in material, energy, and water circulation, and it plays an important part in influencing the region’s climate
Cuesta et al [7] documented the seasonal evolution of the Saharan atmospheric boundary layer (SABL) by using a mobile multiplatform atmospheric observatory implemented in Tamanrasset (Algeria) in 2006
Summary
As the largest fixed and semifixed desert in China, the Gurbantunggut Desert has a longperiod of snow in winter and the rapid growth of ephemeral plants in spring, presentingthe obvious seasonal changes in the underlying desert surface type, which could lead to the significantvariety in the near-surface boundary layer over this desert. E “rapid change” of the underlying surface of the spring desert region affects the surface energy budget, which affects the turbulent energy and the stability of the near-surface layer, affecting the changes in temperature, humidity, and wind profile. Wang et al [13] utilized the sounding data of the Taklimakan Desert hinterland and discussed the impacts of sand-dust and precipitation events on the near-surface atmospheric boundary layer structure. Is study revealed the effects of the underlying surface condition changes on the near-surface boundary layer structure, most notably, the effects on the near-surface layer’s temperature and humidity, and changes in the wind profile E objective of this study was to characterize the nearsurface boundary layer structure with a focus on how it evolves under changing surface conditions. e approach taken is to analyze 2017 in situ observations taken at China’s largest fixed/semifixed desert hinterland. is study revealed the effects of the underlying surface condition changes on the near-surface boundary layer structure, most notably, the effects on the near-surface layer’s temperature and humidity, and changes in the wind profile
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