Study on the Clouds Detected by a Millimeter-Wave Cloud Radar over the Hinterland of the Taklimakan Desert in April–June 2018

摘要

This study was the first to conduct high-resolution consecutive detection of clouds over the hinterland of the Taklimakan Desert(TD)from April to June 2018 based on a ground-based Ka-band millimeter-wave cloud radar(MMCR),with focus on the structure and evolution of the desert clouds.We calculated reflectivity factor(Z),cloud boundary,and liquid water content(LWC)by use of the MMCR power spectrum data,which were verified against the observations from cloud profile radar(CPR)on board Cloud Sat.The results show that the TD clouds were mostly medium and high clouds,with thickness generally less than 2 km;moreover,the mean LWCs of these clouds were less than 0.01 gm^(-3),implying that cirrus and stratiform clouds were predominant.For the observed low clouds,however,the average thickness was 3166 m and accompanying drizzles were concentrated within 2.5-4.5 km,indicating that precipitation was more likely to occur in the low clouds.The mean LWC in the TD clouds was 0.0196 gm^(-3),less than that of clean clouds.Compared to other periods,the average durations and LWCs in the TD clouds increased significantly around noon owing to obvious surface sensible heating.The average time for evolution of high clouds into low clouds was approximately 2 h,and the average maximum LWC increased from 0.008 to 0.139 gm;.The results obtained herein provide a key reference for further studies of the structure and evolution characteristics of the desert clouds.