Remote Sensing Systems has just released the GPM Microwave Imager (GMI) ocean product suite.
The Global Precipitation Measurement (GPM) satellite has a microwave radiometer onboard called GMI (GPM Microwave Imager). The GPM satellite was launched on February 27th, 2014 with the GMI instrument started a few days later. One of the primary differences between GPM and other satellites with microwave radiometers is the orbit, which is inclined 65 degrees, allowing a full sampling of all local Earth times repeated approximately every 2 weeks. The GPM platform undergoes yaw maneuvers approximately every 40 days to compensate for the sun’s changing position and prevent the side of the spacecraft facing the sun from overheating.
Instrument Description: GMI is a dual-polarization, multi-channel, conical-scanning, passive microwave radiometer with frequent revisit times.
About Data Products:
Most microwave radiometer ocean data products at RSS are Version-7, with the decimal values representing the processing stages for that instrument, starting with .1. The GMI data have been produced using an updated RTM, Version-8. The V8 brightness temperatures from GMI are different from the V7 brightness temperatures, however, there are essentially no differences between the V7 and V8 ocean products. The GMI V8.1 data are available from April 3, 2014 to the present. We continue processing data as they arrive, with a delay of about 3 to 6 hours.
Gridded data are organized according to observation date. All dates and times are Coordinated Universal Time (UTC), also known as Greenwich Mean Time (GMT), Zulu Time (Z), Universal Time (UT), and World Time.
Each binary data file available from our ftp site consists of fourteen (daily) or six (averaged) 0.25 x 0.25 degree grid (1440,720) byte maps. For daily files, seven ascending maps in the following order, Time (UTC), Sea Surface Temperature (SST), 10 meter Wind Speed (WSPD-LF), 10 meter Wind Speed (WSPD-MF), Atmospheric Water Vapor (VAPOR), Cloud Liquid Water (CLOUD), and Rain Rate (RAIN), are followed by seven descending maps in the same order. Time-averaged files contain just the geophysical layers in the same order [SST, WSPD-LF, WSPD-MF,VAPOR, CLOUD, RAIN].
The data values between 0 and 250 need to be scaled to obtain meaningful geophysical data. To scale the data, multiply by the scale factors listed in the table above. Read routines provided perform the scaling.
The daily, 3-day and monthly maps are stored in appropriate year and month subdirectories. The weekly data files are stored in the /weeks directory.
The file names have the following naming conventions:
| Time | Directory Path | File Name |
| Daily | [year]/[month]/ | fs_yyyymmddv8.1.gz |
| 3-Day | [year]/[month]/ | fs_yyyymmddv8.1_d3d.gz |
| Weekly | weeks/ | fs_yyyymmddv8.1.gz |
| Monthly | [year]/[month]/ | fs_yyyymmv8.1.gz |
Where “fs”, “yyyy”, “mm”, “dd”, and “vv” stand for:
| fs | file specifier | f35 |
| yyyy | year | 2014, 2015 etc. |
| mm | month | 01 (Jan), 02 (Feb), etc. |
| dd | day | 01, 02, etc. |
One can browse the global images or download the data files. Please be sure to read the full description of the data products
Data are available from March 4, 2014 to the present processed as Version 8.1 data. Products are available within 12 hours of instrument observation.
