Analysis of cloud layer structure using radiosonde and cloud radar data in China

Description

The Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) was deployed in Shouxian, Anhui Province, China from May 14 to December 28, 2008. With reference to the cloud structure as detected by ground-based 95GHz radar operated for 2.5 months, radiosonde data obtained during the AMF campaign are used to analyze cloud vertical structure over this area for the entire 8-month period of AMF deployment. Single-layer, two-layer, and three-layer clouds account for 28.0%, 25.8%, and 13.9% of all cloud configurations, respectively. Low, middle, high, and deep convective clouds account for 20.1%, 19.3%, 59.5%, and 1.1% of all clouds found at the site, respectively. The average cloud-base height, cloud-top height, and cloud thickness for all clouds are 5912 m, 7639 m, and 1727 m, respectively. The thicknesses of all layers in two-layer and three-layer clouds are less than that of a single-layer cloud with an average difference of -867 m. The maxima of cloud-top height and cloud thickness occurred at 13:30 Local Standard Time (LST) for single-layer and uppermost-layer of multiple layers. They occurred at 19:30 LST for the lower-layer clouds in multiple-layer cloud systems. The diurnal variations in the thickness of upper-level clouds are larger than those of lower-level clouds. In general, the thickness of cloud layers does not change from summer to autumn, but multi-layer clouds occurred more frequently in the summer. The absolute differences in cloud-base heights from radiosonde and those from the Micropulse Pulse Lidar (MPL) and ceilometer are less than 500 m for 77.0%/69.4%, respectively.