Principal Investigator:

Dr. Eastwood Im
M.S. 300-227, Jet Propulsion Laboratory
4800 Oak Grove Drive, Pasadena, CA 91109
Voice: (818) 354-0492; E-mail: eastwood.im@jpl.nasa.gov

Co-Investigators:

Dr. Stephen L. Durden, Jet Propulsion Laboratory
Mr. Andrew Berkun, Jet Propulsion Laboratory
Ms. Wendy Edelstein, Jet Propulsion Laboratory
Dr. Ziad S. Haddad, Jet Propulsion Laboratory
Dr. John Huang, Jet Propulsion Laboratory
Dr. Eric A. Smith, Florida State University

Proposal Title: A Second-Generation Precipitation Radar (PR-2) Adaptable for Multi-Mission and Multi-Orbit applications

Global rainfall is the primary distributor of latent heat through atmospheric circulation. The recently launched Tropical Rainfall Measuring Mission satellite is dedicated to advance our understanding of tropical precipitation patterns and their implications on global climate and its change. The Precipitation Radar (PR) aboard the satellite is the first radar ever flown in space and has provided exciting, new data on the 3-D rain structures for a variety of scientific uses. However, due to the limited mission lifetime and the dynamical nature of precipitation, the TRMM PR data acquired cannot address all the issues associated with precipitation, its related processes, and the long-term climate variability. In fact, a number of new post-TRMM mission concepts have emerged in response to the recent NASA Post-2002 RFI. Most of them require a PR type radar with enhanced capabilities.

In this proposal, we seek to develop a breadboard electronics model, and demonstrate its performance, for a second-generation spaceborne precipitation radar (PR-2). The key PR-2 electronics system will possess the following capabilities:

• A 13.6/35 GHz dual frequency radar electronics that has Doppler and dual-polarization capabilities.

• Digital chirp generation and the corresponding on-board pulse compression scheme. This will allow a significant improvement on rain signal detection without using the traditional, high-peak-power transmitters and without sacrificing the range resolution.

• Radar electronics and algorithm to adaptively scan the antenna so that more time can be spent to observe rain rather than clear air.

• Built-in flexibility on the radar parameters and timing control such that the same radar can be used by different future rain missions. This will help to reduce the overall instrument development costs.

We proposed to conduct ground-based testing and one engineering test flight on the NASA DC-8 aircraft to demonstrate the PR-2 system capabilities. In these tests, the PR-2 electronics system will be integrated with the existing scanning antenna and the power amplifier for the JPL Airborne Rain Mapping Radar. This will reduce the cost of our proposed effort.

We also propose to conduct a preliminary design study for a large but light weight, dual-frequency, wide-swath scanning, deployable antenna for future spaceborne rain missions.

Durden, S.L., E. Im, F.K. Li, W. Ricketts, A. Tanner, and W. Wilson, 1994: ARMAR: An airborne rain mapping Radar. J. Atmos. Oceanic Tech., 11, 727-737.