The 1B-CPR-FL product is produced in the same manner as the 1B-CPR except that the geolocation data are produced from the raw GPS data in place of the geolocation data provided with the Definitive Ephemeris.
During normal processing, to produce the level 1B-CPR product, the Definitive Ephemeris is used after it arrives, to determine the geolocation of each CloudSat profile. The Definitive Ephemeris contains the latitude, longitude and altitude of the satellite at 1-second intervals. One disadvantage of using the Definitive Ephemeris for geolocation is that it is only available once per day at approximately 16:00 UTC. This file contains the orbital parameters for 0000 UTC through 2359 UTC on the previous Julian day. Thus the standard 1B-CPR data product will not be available until 16-40 hours after the data are actually taken.
In order to provide a "First Look" 1B-CPR product, the CloudSat DPC will process the GPS location data, that are contained in the SSOH data stream, to produce the 1B-CPR-FL. Since GPS data are available with each download of CPR science data, the DPC should be able to provide a 1B-CPR product, based on GPS location data, in less than 10 minutes of the time that data are received at the DPC.
The time lag, between the actual CPR measurement and the time the 1B-CPR-FL products is available at CIRA, is based on the combined lag times of the data downlink, transfer of data from the downlink site to the RSC, processing at the RSC, transfer of data to the DPC, and processing at the DPC. The estimated time is as follows:
a. Minimum Data Latency = 45 minutes
b. Maximum Data latency = 28.5 hours
c. Expected Data Latency = 4.5 hours