Inter-Comparisons between Radiometric and Geometric Cloud Top Height Products

Abstract:

The accurate retrieval of cloud properties such as cloud top height from satellite imagery is important for early warning of severe weather development and for reliable aviation weather forecasts. This paper describes a comparison between cloud top height products (Stereo-CTH), determined using an algorithm based on stereoscopy, and operational cloud top height products which are generated by using the Clouds from AVHRR Extended (CLAVR-x) cloud processing system. Both methods work with Geostationary Operational Environmental Satellite (GOES) data, and in limited cases, we also compare with data from CALIPSO. The Stereo-CTH algorithm is based on matching images of the same or similar spectral bands acquired quasi-simultaneously by satellites from two or three different vantage points. The CTH product generated by CLAVR-x is based on the Algorithm Working Group (AWG) Cloud Height Algorithm (ACHA) and uses only Infrared (IR) observations from a single sensor.

The Stereo-CTH algorithm was applied to GOES data when all three satellites (GOES 13-15) were operational at the same time allowing for the generation of a two-satellite CTH in areas of overlap between two satellites and a three-satellite CTH where geographic coverage is available for all three satellites. The comparison was applied to the three-satellite CTH, which is considered the best quality data.

The comparison between the two products displays an approximately linear relationship between the Stereo-CTH and the CLAVR-CTH for most of the data as shown in Figure 1. The observed differences are investigated and discussed.