Skip to content. | Skip to navigation

Personal tools
You are here: GES DISC Home Precipitation Documentation guide TRMM Visible-IR Scanner L1A (TRMM 1A01)

TRMM Visible-IR Scanner L1A (TRMM 1A01)

Message Alert Notification THIS DOCUMENT IS AVAILABLE ON THE GES DISC WEB SITE FOR HISTORICAL INFORMATION PURPOSES ONLY. Information provided in this document may not be accurate. We recommend checking other sources related to these data or sensors to acquire reliable and updated information.

Explanation: The Dataset or Sensor Guide Document you are accessing is no longer actively maintained. The Dataset Guide Documents were created for earlier versions of the NASA EOSDIS system. The content of these documents, particularly with regard to characteristics of the data or technical descriptions of a sensor, is likely still accurate. However, information such as contact names, phone numbers, mailing addresses, email addresses, software programs, system requirements, and data access procedures may no longer be accurate. We therefore recommend searching for updated information from other sites to insure that reliable and current information is obtained.



The TRMM Visible and Infrared Scanner (VIRS) is a five-channel visible/infrared radiometer, which builds on the heritage of the Advanced Very High Resolution Radiometer (AVHRR) instrument flown aboard the NOAA series of Polar-Orbiting Operational Environmental Satellites (POES). The VIRS detects radiation at 1 visible, 2 near infrared and 2 thermal infrared wavelengths, allowing determination of cloud coverage, cloud top height and temperature, and precipitation indices. The central wavelengths for the VIRS channels are 0.63, 1.60, 3.75, 10.8, and 12.0 microns. All channels are in operation during the daytime, but only channels 3, 4 and 5 operate during the nighttime.

The Level 1A product file (1A01) is a concatenation of the Level 0 data with a header record and, as such, is reversible to Level 0. The header record contains information pertaining to orbit times, orbit number, times of the first scan, and number of scans, among other things. The Level 0 data contain the actual channel data expressed as "sensor counts". A Level 1A file contains data for a single orbit and has a file size of about 31 MB (uncompressed). There are 16 files of VIRS 1A01 data produced per day.

Spatial coverage is between 38 degrees North and 38 degrees South owing to the 35 degree inclination of the TRMM satellite.


Contacts for Data Access Information

Goddard DAAC
Hydrology Data Support Team, Code 610.2
NASA Goddard Space Flight Center
Greenbelt, MD 20771

301-614-5224 voice
301-614-5268 fax



Data Center Identification

Goddard Space Flight Center Distributed Active Archive Center, NASA


File Specifications for TRMM Products - Version 7.00 Document contains file specifications for each algorithm written by PPS. This document replaces the previous Volumes 3 and 4 Interface Control specifications for Level 1, 2 and 3 TRMM products.


Document Information

Document Revision Date:Fri May 17 10:09:50 EDT 2002
Document Review Date: Wed May 15 10:24:19 EDT 2002
Document Author: Hydrology Data Support Team

Document Actions
NASA Logo -
NASA Privacy Policy and Important Notices
Last updated: Jul 18, 2013 02:36 PM ET