Exploring the Relationships of Atmospheric Water Vapor Contents and Different Land Surfaces in a Complex Terrain Area by Using Doppler Radar

Hezhen Lou,Ya Luo,Shengtian Yang,Jun Zhang,Chaojun Li,Xiaoyu Ren,Mingyong Cai

doi:10.3390/atmos12050528

Abstract

Changes in atmospheric water vapor mainly occur in the atmospheric boundary layer. However, due to many factors, such as orography and ground thermal dynamic conditions, the change trends and transformation law of atmospheric water vapor contents above different surfaces are still unclear. In this work, a Doppler weather radar with high spatial-temporal resolution was used to monitor the variations and transformations of water vapor contents over different land surfaces for two years. The results show that the atmospheric water vapor content shows a very good positive correlation with elevation at altitudes between 600 m and 1200 m, while different land surfaces have delicate impacts on atmospheric water vapor contents, such as extreme values appearing above impervious urban surfaces, uniform distributions appearing over water body and vegetated surfaces being wet but avoiding extreme conditions. Compared with previous studies, the results and conclusions of this study are mainly derived from accurate direct observations based on high-resolution radar. Identifying the distribution and transformation of water vapor over different surfaces can enhance our understanding of the movement and variation of atmospheric water vapor over complex terrain and different land surfaces, and improve the planning and construction capacity of different surfaces, such that humankind can mitigate the severe disasters caused by drastic changes in atmospheric water vapor.

Highlights

Land surface-atmosphere interactions play an essential role in the climate system
By selecting different land surfaces in the southwest portion of the radar scanning range to analyze the effects of atmospheric water vapor content changes, we find that vegetation and farmland surfaces are the main land surface types
Stage S3 enters the height at which condensation descent of atmospheric water vapor occurs; the accumulated instantaneous reflectivity (IR) is in a stage of slow decrease, and the IR decreases by 1.9% for each 100 m increase on average, but the moisture content remains at a high level continuously, with an average accumulated IR of 268.1 dBZ, 32.7% higher than that of the previous stage

Summary

Introduction

Land surface-atmosphere interactions play an essential role in the climate system. They strongly modulate regional climates and have impacts on the global scale [1,2]. Interactions between the land surface and the atmospheric boundary layer are highly dependent on the surface characteristics, and the land surface is characterized by different types of soil, root zone moisture, and vegetation, all of which cause heterogeneous surface fluxes (i.e., momentum, sensible heat, and latent heat fluxes) [3]. Studying the influence of surface heterogeneity on atmospheric characteristics is a key aspect for better understanding land–atmosphere interactions [4]. The Earth’s weather and climate are heavily influenced by the amount of water vapor present in the atmospheric boundary layer. The low atmosphere can contain a large volume of water vapor that traps radiant energy and causes the temperature to increase [5]; this atmospheric layer is significantly affected by orography and land surface conditions due to energy changes

Methods

Results

Discussion

Conclusion