Toward Understanding the Properties of High Ice Clouds at the Naqu Site on the Tibetan Plateau Using Ground-Based Active Remote Sensing Measurements Obtained during a Short Period in July 2014

Abstract This study describes the microphysical properties of high ice clouds (with bases above 5 km) using ground-based millimeter cloud radar cirrus-mode observations over the Naqu site of the Tibetan Plateau (TP) during a short period from 6 to 31 July 2014. Empirical regression equations are applied for the cloud retrievals in which the parameters are given on the basis of a review of existing literature. The results show a unimodal distribution for the cloud ice effective radius r e and ice water content with maximum frequencies around 36 μ m and 0.001 g m −3 , respectively. Analysis shows that clouds with high ice r e are more likely to occur at times from late afternoon until nighttime. The clouds with large (small) r e mainly occur at low (high) heights and are likely orographic cumulus or stratocumulus (thin cirrus). Further analysis indicates that ice r e decreases with increasing height and shows strong positive relationships between ice r e ( μ m) and depth h (m), with a regression equation of r e = 35.45 + 0.0023 h + (1.7 × 10 −7 ) h 2 . A good relationship between ice r e and temperature T (°C) is found, r e = 44.65 + 0.1438 T , which could serve as a baseline for retrieval of characteristic ice r e properties over the TP.