A novel reconstructed method for air spatial relative humidity near the surface in arid regions

The near-surface air relative humidity (RH) in arid desert areas is a critical environmental indicator that significantly influences the desertification process, sandy plants, water harvesting, sand particle transport as well as desert ecological maintenance. However, existing spatial distribution models of RH fail to consider the coupling effects of temperature, wind speed and topography on RH distribution. To address this issue, we propose a spatial reconstructed model of RH that incorporates wind speed, altitude difference, temperature, roughness and obstacle height and their physical effects. Our model can accurately predict RH with a small error (less than 4.3%), supported by wind tunnel experiments and field tests at flat sandy surfaces and dune surfaces. Dynamic positive coupling factors (DPCF) have a significant impact on spatial RH on top surfaces of dune, which boils down to those of high wind speed and topography. Finally, the reconstruction process of the spatial distribution of air RH based on our model and limited fixed-point monitoring data (humidity, wind field, topography, etc.) is introduced. This work provides new insights to accurately reconstruct the spatial distribution of RH in arid regions.