TRMM_3A55: Monthly 3-D Radar Rain Structure for Ground Validation

TRMM_3A55 provides monthly 3-D structure information derived from ground-based radar data for the Tropical Rainfall Measuring Mission (TRMM) Ground Validation effort. The dataset contains arrays of 3-D reflectivities, vertical profiles, and Contoured Frequency by Altitude Diagram (CFAD) data, with a 2 km horizontal resolution and vertical resolution of 1.5 km up to 19.5 km altitude. It is produced by NASA from quality-controlled data collected at primary sites in Darwin, Houston, Kwajalein, and Melbourne, plus NASA Wallops Flight Facility.

Use Cases

• Validating TRMM satellite precipitation products against ground-based radar reflectivity data.
• Analyzing the vertical structure of precipitation via Contoured Frequency by Altitude Diagrams (CFADs).
• Comparing rain characteristics across different geographic sites (e.g., Texas vs. Florida multi-radar composites).
• Studying drop size distributions (DSD) using instrument data referenced in the collection methodology.

Strengths

• Provides detailed 3-D spatial resolution (2 km horizontal, 1.5 km vertical) for radar reflectivity.
• Data is quality-controlled as part of a NASA-led Ground Validation (GV) effort for satellite calibration.
• Covers multiple long-term primary validation sites, including a significant effort at NASA Wallops Flight Facility.

Limitations

• Column names and exact data structure are not provided in the available metadata.
• Conflicting 'last updated' dates exist between sources (2015 on NASA Earthdata vs. 2026 on Data.gov).
• Specific row counts, file sizes, and detailed license terms are not available.

Provenance

Source

National Aeronautics and Space Administration (NASA), Tropical Rainfall Measuring Mission (TRMM) Ground Validation effort.

Collection Method

Data collected from ground-based radar, rain gauges, and disdrometers (Joss Waldvogel, Parsivel, 2D video) at validation sites, processed into 3-D arrays and CFADs.

Time Range

Monthly aggregation (specific date range not provided).

Freshness

2026-04-09 21:27:56.436536 (from Data.gov, conflicting with NASA Earthdata date)

Geography

Primary sites: Darwin, Australia; Houston, Texas; Kwajalein, Republic of the Marshall Islands; Melbourne, Florida; and NASA Wallops Flight Facility, Virginia. Coverage areas vary from 300km x 300km for single sites to 724km x 568km for Texas composites.