TRMM 2A55UW: Ground Radar 3D Reflectivity for Satellite Validation

TRMM_2A55UW is a Level 2 product from the Tropical Rainfall Measuring Mission Ground Validation effort, providing a 3D cartesian grid of radar reflectivity and velocity. It is generated only for volumes of interest, defined as those within +/-15 minutes of satellite overpass times or with significant rainfall. The data supports validation of satellite precipitation estimates against ground-based measurements from primary sites in Darwin, Houston, Kwajalein, and Melbourne.

Use Cases

• Validating TRMM satellite precipitation estimates based on ground-based radar reflectivity fields.
• Analyzing 3D storm structure and dynamics using 2km horizontal and 1km vertical resolution grids.
• Comparing rainfall measurements from different ground-based instruments (radar, rain gauges, disdrometers) at primary validation sites.
• Studying drop size distributions using data from Joss-Waldvogel, Parsivel, and video disdrometers.

Strengths

• Provides high-resolution 3D data with a 2km horizontal and 1km vertical grid over a 150x150km area.
• Data is quality-controlled as part of a key NASA/TRMM validation effort involving multiple instrument types.
• Cross-platform presence on datagov and nasa_earthdata signals its importance and curation.

Limitations

• Metadata conflicts exist: last update dates range from 2003-12-31 to 2026-04-10, suggesting potential staleness or inconsistent reporting.
• Column names and row counts are unknown across all sources, limiting understanding of the data structure.
• The dataset is not created for every radar volume, only for 'volumes of interest', which may introduce sampling gaps.

Provenance

Source

University of Washington TRMM Ground Validation products, under the National Aeronautics and Space Administration.

Collection Method

Data is collected from ground-based radar, rain gauges, and disdrometers, quality-controlled, and processed via NCAR SPRINT interpolation.

Freshness

Most recent update reported is 2026-04-10, but a conflicting source reports 2003-12-31.

Geography

Primary validation sites are Darwin (Australia), Houston (Texas), Kwajalein (Marshall Islands), and Melbourne (Florida), with additional efforts at NASA Wallops Flight Facility.