Validation of surface retrieved cloud properties using in-situ aircraft observations at the Atmospheric Radiation Measurement Program (ARM) Southern Great Plains site

Description

Number concentration and effective radius of cloud droplets value added products (VAPs), which are the important factors in understanding Aerosol-Cloud Interactions (ACI), have been retrieved using the multi-filter rotating shadow-band radiometer (MFRSR) and microwave radiometer (MWR) surface measurements at the Atmospheric Radiation Measurement Program (ARM) South Great Plains (SGP) and Azores sites. The long-term ARM Climate Research Facility (ACRF) data provide invaluable constrains to numerical models and insights in understanding ACI. In this study, we validate the VAPs of number concentration and effective radius of cloud droplets at the SGP site using in-situ aircraft observations during the Routine ARM Aerial Facility (AAF) Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign of shallow boundary-layer clouds. Both effective radius and number concentration of cloud droplets are higher than the aircraft best estimate data during the field campaign period. Analysis focusing on specific cloud events shows that under relatively thick-cloud cover conditions, the retrieved effective radius matches well with the aircraft data, but the retrieved cloud droplet number concentrations reveal large positive biases. Meanwhile, under relatively thin-cloud cover conditions, the retrieved effective radius shows a large positive bias and cloud droplet number concentrations match well with the aircraft data. Here, the total sky imager is used to separate the two different cloud-covered conditions. Further detailed analysis will be pursued to determine how the retrieved cloud properties are affected by cloud characteristics and environmental conditions.