TOVS/ATOVS 1b DLT Data Description


This is a description of the format for the entire TOVS/ATOVS 1b dataset found on digital linear tape (DLT). As of February 2001, the Climsat group has archived all HIRS, MSU, and AMSU 1b data from October 1978 to the present. Data prior to January 1998 was transferred from 8mm to DLT, whereas data starting in 1998 has been retrieved via ftp. All data has been stored on DLT by using tar in compressed mode. To read any file from DLT, simply use the tar command "tar xvf /dev/rmt/${drive}cn" where ${drive} indicates the appropriate drive number, c is the compressed mode and n is the no rewind option. All TOVS/ATOVS 1b DLTs have chronologically ordered tar files.

CLIMSAT HIRS 1b Description

Any given full HIRS DLT generally contains 14 to 15 months of HIRS 1b data for one satellite. Each tar file on the HIRS 1b DLT contains one day of data, so each full HIRS 1b DLT contains between 400 to 500 files (or days) of data. Each tar file contains all the orbital files for a given day (~ 14 orbits/day) and the size of the daily tar file is ~60 Mbytes. This file structure allows the user to easily skip through the DLT to find data for a particular time period. All HIRS data are stored compressed on DLT 4000 tapes.

CLIMSAT MSU 1b Description

One MSU 1b DLT contains all the MSU 1b data for the entire 23-year period. Since the MSU 1b orbital file sizes are 40X smaller than the HIRS 1b orbital files, each tar file contains one month of data for all satellites. Therefore, each monthly tar file contains 800-900 orbital files for the typical time period when two satellites are collecting data. Monthly tar files are ~100 Mbytes for these periods. All MSU data are stored compressed on a DLT 4000 tape.

CLIMSAT AMSU 1b Description

The AMSU 1b data are classified by satellite like the HIRS data. One DLT typically stores 10 months of data. Data are stored in daily tar files with each tar file containing both AMSU-A and AMSU-B data. A full AMSU DLT tape typically contains 280 files. Each daily tar file contains approximately 130 Mbytes of data. All AMSU data are stored compressed on DLT 7000 tapes.