GPM PR on TRMM Reflectivity, Precipitation Characteristics and Rate, at Surface and Profile L2 1.5 hours V06 (GPM_2APR) at GES DISC

This is the new, GPM-like, format for TRMM Precipitation Radar L2 data that now incorporates what was known as 2A21, 2A23 and 2A25 datasets.

The primary purpose of 2A21 is to compute the path-integrated attenuation (PIA) using the surface reference technique (SRT). The surface reference technique rests on the assumption that the difference between the measurements of the normalized surface cross section outside and within the rain provides an estimate of the PIA. The secondary purpose of 2A21 is to compute the normalized radar cross sections ("sigma-not" or Normalized Radar Cross-Sectin (NRTS)) of the surface under rain-free conditions.

Main objectives of 2A23 are as follows: (a) Detection of bright band (BB) and determination of the height of BB, the strength of BB, and the width (i.e. thickness) of BB when BB exists. (b) Classification of rain type into the following three categories: - stratiform, - convective, - other, where "other" means (ice) cloud only and/or maybe noise. (c) Detection of shallow isolated and shallow non-isolated. (d) Output of Rain/No-rain flag. (e) Computation of the estimated height of freezing level. (f) Output of the height of storm top.

The objectives of 2A25 are to correct for the rain attenuation in measured radar reflectivity (Zm) and to estimate the instantaneous three-dimensional distribution of rain from the TRMM Precipitation Radar (PR) data. The estimated vertical profiles of attenuation-corrected radar reflectivity factor (Ze) and rainfall rate (R) are given at each resolution cell of the PR. The estimated rainfall rate at the actual surface height and the average rainfall rate between the two predefined altitudes (2 and 4 km) are also calculated for each beam position.

Changes in horizontal resolution resulting from the TRMM boost that occurred on 24 August 2001:

Pre-Boost (before 7 August 2001): Temporal Resolution: 91.5 min/orbit ~ 16 orbits/day; Swath Width: 215 km; Horizontal Resolution: 4.3 km

Post-Boost (after 24 August 2001): Temporal Resolution: 92.5 min/orbit ~ 16 orbits/day; Swath Width: 247 km; Horizontal Resolution: 5.0 km

Data and Resources

Field Value
accessLevel public
bureauCode {026:00}
catalog_@context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
catalog_@id https://data.nasa.gov/data.json
catalog_conformsTo https://project-open-data.cio.gov/v1.1/schema
catalog_describedBy https://project-open-data.cio.gov/v1.1/schema/catalog.json
citation Tropical Rainfall Measuring Mission (TRMM). 2018-07-03. GPM_2APR. GPM PR on TRMM Reflectivity, Precipitation Characteristics and Rate, at Surface and Profile L2 1.5 hours V06. Greenbelt, MD. Archived by National Aeronautics and Space Administration, U.S. Government, Goddard Earth Sciences Data and Information Services Center (GES DISC). https://doi.org/10.5067/GPM/PR/TRMM/2A/06. https://disc.gsfc.nasa.gov/datacollection/GPM_2APR_06.html. Digital Science Data.
creator Tropical Rainfall Measuring Mission (TRMM)
data-presentation-form Digital Science Data
graphic-preview-file https://docserver.gesdisc.eosdis.nasa.gov/public/project/GPM/browse/GPM_2APR.png
identifier C1536083677-GES_DISC
issued 2018-07-01
landingPage https://doi.org/10.5067/GPM/PR/TRMM/2A/06
language {en-US}
metadata_type geospatial
modified 2018-07-05
programCode {026:001}
publisher NASA/GSFC/SED/ESD/GCDC/GESDISC
release-place Greenbelt, MD
resource-type Dataset
series-name GPM_2APR
source_datajson_identifier true
source_hash 4725a4c208bfcec38f2225e9b619573ab7914c8d
source_schema_version 1.1
spatial {"type": "Polygon", "coordinates": [[[-180.0, -38.0], [180.0, -38.0], [180.0, 38.0], [-180.0, 38.0], [-180.0, -38.0]]]}
temporal 1997-12-07T00:00:00Z/2015-04-01T23:59:59.999Z
theme {TRMM,geospatial}
Groups
  • AmeriGEOSS
  • National Provider
  • North America
Tags
  • amerigeo
  • amerigeoss
  • atmosphere
  • ckan
  • earth-science
  • geo
  • geoss
  • national
  • north-america
  • precipitation
  • radar
  • spectral-engineering
  • united-states
isopen False
license_id notspecified
license_title License not specified
maintainer JUN AWAKA
maintainer_email awaka@de.htokai.ac.jp
metadata_created 2025-11-22T16:36:06.048691
metadata_modified 2025-11-22T16:36:06.048695
notes This is the new, GPM-like, format for TRMM Precipitation Radar L2 data that now incorporates what was known as 2A21, 2A23 and 2A25 datasets. The primary purpose of 2A21 is to compute the path-integrated attenuation (PIA) using the surface reference technique (SRT). The surface reference technique rests on the assumption that the difference between the measurements of the normalized surface cross section outside and within the rain provides an estimate of the PIA. The secondary purpose of 2A21 is to compute the normalized radar cross sections ("sigma-not" or Normalized Radar Cross-Sectin (NRTS)) of the surface under rain-free conditions. Main objectives of 2A23 are as follows: (a) Detection of bright band (BB) and determination of the height of BB, the strength of BB, and the width (i.e. thickness) of BB when BB exists. (b) Classification of rain type into the following three categories: - stratiform, - convective, - other, where "other" means (ice) cloud only and/or maybe noise. (c) Detection of shallow isolated and shallow non-isolated. (d) Output of Rain/No-rain flag. (e) Computation of the estimated height of freezing level. (f) Output of the height of storm top. The objectives of 2A25 are to correct for the rain attenuation in measured radar reflectivity (Zm) and to estimate the instantaneous three-dimensional distribution of rain from the TRMM Precipitation Radar (PR) data. The estimated vertical profiles of attenuation-corrected radar reflectivity factor (Ze) and rainfall rate (R) are given at each resolution cell of the PR. The estimated rainfall rate at the actual surface height and the average rainfall rate between the two predefined altitudes (2 and 4 km) are also calculated for each beam position. Changes in horizontal resolution resulting from the TRMM boost that occurred on 24 August 2001: Pre-Boost (before 7 August 2001): Temporal Resolution: 91.5 min/orbit ~ 16 orbits/day; Swath Width: 215 km; Horizontal Resolution: 4.3 km Post-Boost (after 24 August 2001): Temporal Resolution: 92.5 min/orbit ~ 16 orbits/day; Swath Width: 247 km; Horizontal Resolution: 5.0 km
num_resources 11
num_tags 13
title GPM PR on TRMM Reflectivity, Precipitation Characteristics and Rate, at Surface and Profile L2 1.5 hours V06 (GPM_2APR) at GES DISC