Introduction to the Detecting Station Network of Desert Atmospheric Boundary Layer and Observed Experiments over Northwest China Deserts

The desertification area of China was 261.2×104 km², which has produced significant effects on the weather, climate and environment over Northwest China. In order to study the weather, climate and environment of the Northwest China Deserts, the detecting station network of desert atmospheric boundary layer was designed and established, and observed experiments were conducted. The detecting station network covered three deserts of Northwest China (Taklimakan Desert, Gurbantunggut Desert and Badain Jaran Desert ), and abided by three vertical line and one horizontal line. The detecting projects including boundary layer meteorological parameters, surface radiation, surface fluxes, soil parameters, ambient air quality; dust aerosol properties, water vapor profiles, and aeolian sand movement. Based on observed experiments, the characteristics of boundary layer meteorological parameters, surface radiation, surface fluxes, soil parameters, ambient air quality, dust aerosol properties, water vapor profiles and aeolian sand movement over Northwest China Deserts were obtained. Results indicated that depth of the convective boundary layer can reach 5000m on summer afternoons. In desert regions, the diurnal mean net radiation was effected significantly by dust weather, and sensible heat was much greater than latent heat accounting about 40-50% in the heat balance of desert. The surface soil and dust size distributions of Northwest China Deserts were obtained through widely collecting samples, results showed that the dominant dust particle size was PM₁₀₀ within 80m height, on average accounting for 60–80% of the samples, with 0.9–2.5% for PM_0–2.5, 3.5–7.0% for PM_0–10 and 5.0–14.0% for PM_0–20. The time aeolian sand movement of Taklimakan Desert, Gurbantunggut Desert and Badain Jaran Desert accounted for 0.48%, 7.3%×10^-5 and 1.9% of the total time within a year, and the threshold friction velocity for aeolian sand movement were 0.22-1.06m/s, 0.29-1.5m/s and 0.21-0.59m/s, respectively.