PNNL

Abstract

We develop a new approach that resolves cloud area distributions of single-layer shallow cumuli from ground-based observations. Our simple and computationally inexpensive approach uses images obtained from Total Sky Imager and complementary information on cloud base height provided by lidar measurements to estimate cloud equivalent diameter (CED) over a wide range of cloud sizes (about 0.01-3.5km) with high temporal resolution (30s). We demonstrate the feasibility of our approach by comparing the estimated CEDs with those derived from collocated and coincident high-resolution (0.03 km) Landsat cloud masks with different spatial and temporal patterns of cloud cover collected over the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site. Our approach produces agreement within 10% when Landsat cloud sizes undergo a similar sampling strategy, and a ~16% low bias for TSI CED compared with full cloud sizes that extend beyond the 3.5km limit of the TSI field of view (FOV).