TRMM-LBA Flight Leg Analysis Common Radar Product

During each of the TRMM field campaigns (FC), ground-based radars (GBR) and airborne microphysical platforms interrogated coincident volumes of cloud in order to describe vertical profiles of hydrometeors in a variety of cloud structures and environments. Robust scientific interpretation of these datasets, as they pertain to TRMM algorithm development and model intercomparison, will be facilitated if in situ data are intercompared with collocated volumes of ground-based radar data. For example, GBR products can serve as an overall guide in the interpretation of microphysical products relative to the observed precipitation echo structure along a given flight track. The documention (in PDF) provides a common radar product definition (CRPD) for specific application to the TRMM-LBA field campaign GBR volumetric data collected during aircraft missions that have, or will be selected for generation of a TRMM common microphysics product (cf. TRMM Common Microphysics Product Definition [CMPD]; S. Yuter, U. of Washington). In this sense, the CRPD is best described as the GBR equivalent of the CMPD, which served as the template for the documention (in PDF).

The intended users of the TRMM-LBA Common Radar Product are not necessarily radar experts per se but rather TRMM PIs who are analyzing data from airborne instruments and would like a ground-based radar data set to compare to or to set context for diverse in situ and remotely sensed data fields. The primary applications of the GBR data for these users are:

  • GBR data for use in conjunction with airborne remote sensors such as AMPR, AMMR, ARMAR, and EDOP ­ requires a three-dimensional "swath" of data on either side of a flight track (nominally +/- 10 km width perpendicular to flight track) and for the full depth of the storm from the surface to echo top.
  • GBR data for use in conjunction with TRMM satellite data in additional to airborne remote sensors and/or in situ data.
    • To serve the needs of these users a description of the TRMM-LBA radar product i s provided. This product is in ASCII format to eliminate the need for radar software package s that are usually required to view radar data.

    Essentially, the GBR data consist of gridded slabs of volumetric radar data that correspond temporally and spatially to a prioritized list of flight tracks conducted by airborne microphysical platforms during the TRMM-LBA FC. Priority flight-track segments are defined by a starting time (UTC), starting latitude/longitude and ending latitude/longitude. The leg orientation as defined in this document is the east-west component of the leg vector pointing from start to ending leg points. Utilizing the TRMM-LBA flight leg coordinates, corresponding gridded radar data files for flight tracks occurring within 150 km of the S-pol radar were generated in ASCII format for the volume of atmosphere bounded by the flight leg endpoints (with ~5 km of "extra" data appended to the end of each leg ) in the along track plane, +/- 10 km in the cross-track plane, and an altitude of 18 km in the vertical plane. Note that the CRPD and CMPD both invoke ASCII data formats for consistency. ASCII- formatted data will facilitate use of the GBR product by a multitude of users in the algorithm, modeling and TRMM community at large that may be unfamiliar with more commonly used raw/processed radar data formats (e.g., IRIS, UF, DORADE, CDF, HDF etc.).

    The GBR data is available for download here in a gzipped tar archive.