Characteristics of multi-layer clouds observed using ceilometer observations over Leh-Ladakh: A high-altitude cold desert region

Abstract

The Leh-Ladakh region is a high-altitude cold desert (3255 m above mean sea level), located under the rain shadow of the Himalayas, display various cloud features crucial to understand the extreme weather conditions. Global Satellite Mapping of Precipitation (GSMaP) parameter helped to show that almost 37 % of rain falls over Leh-Ladakh region (7─38°N, 62─100°E) during last 23 years of monsoon season. Low rainfall though facing extreme rainfall events, need a continuous monitoring of cloud measurements. In the present study, cloud base height (CBH) variability is investigated using Ceilometer Lidar measurements, complemented by Moderate Resolution Imaging Spectroradiometer (MODIS), European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5) during September 2022─August 2023. Our comparative findings suggested that Ceilometer's CBH measurements aligned with calculated MODIS CBH, whereas ERA5 CBH gets underestimate. Further, Ceilometer measurements of multi-layer clouds, consist of three distinct layers. These day-to-day seasonal variations in clouds show highest occurrence frequencies during the pre-monsoon (67.94 %) and monsoon (98 %), clearly reflects the onset and active phases of the Indian summer monsoon. Further, July recorded with the highest cloud occurrence frequency (84.03 %), consisting of single-layer (15.92 %), double-layer (25.98 %) and triple-layer (42.13 %) clouds. Our study inferred a high fraction of mid-level (∼3─6 km; 77.53 %) clouds during winter, pre-monsoon, monsoon, and post-monsoon seasons. Thus, altostratus, altocumulus, nimbostratus, or altogether were particularly prominent across all the seasons, with their variability linked to orographic and climatic factors.