Task 148

CloudSat-TRMM Intersection Processing

Principal Investigator(s):

Shen-Shyang Ho


David Starr

Last Updated:

October 26, 2012 15:25:41

Description of Problem

Before the launch of CloudSat in April 2006, the Ku-band (13.8 GHz) Precipitation Radar, PR, aboard the Tropical Rainfall Measurement Mission (TRMM) was the only spaceborne radar capable of making rainfall measurements. The TRMM PR is designed for precipitation measurements over the tropics and is capable of measuring most rain rates greater than 0.7 mm/h with its = 70 dB dynamic range. However, its 17 dB sensitivity effectively makes the PR unable to measure light rains with rain rates less than or equal 0.7 mm/h. Although the W-band (94 GHz) Cloud Profiling Radar, CPR, flown on CloudSat is designed for observing the vertical structure of clouds it is also capable of measuring light rains. The CPR’s light rain capability naturally complements the PR. In addition, the CloudSat CPR offers information about the cloud structure above the rain which is useful in providing better attenuation estimate for the PR.

The synergy of these two spaceborne radars possesses such a potential for benefiting the researches of cloud precipitation systems that it is only logical to pursue a combined product of the two. In this project, the main objective is the design and implementation of efficient and effective algorithm to extract the 2D-CloudSat-TRMM intersection data product.

Scientific Objectives and Approach

Develop an intersect algorithm to find the intersections of CloudSat and TRMM orbits, given a time precision for their intersections. The algorithm can be optimized based on the facts that CloudSat is sun-synchronous. Thus, regions that do not make a specific angle with the sun rays can be ignored.


1. Implemented a brute force algorithm for verification. Completed.
2. Designed and implemented the intersect algorithm in Matlab. Completed.
3. Run the intersect algorithm on historical data. In Progress.