Effective around 12:00 UTC 10 June the MHS and ATMS input to real-time IMERG suddenly became unavailable due to an unexpected change in NOAA protocols. While PPS scrambles to remedy the issue, the data content of the Early and Late Runs may be reduced for the next several days, meaning lower Quality Index due to longer morphing of microwave estimates and greater contributions by IR.
Due to a correction to the GPM IMERG algorithm implemented by the GPM science team, PPS will retract and reprocess all IMERG V06A Final Run GPM and TRMM era data including GIS products as IMERG V06B starting on June 05, 2019. If you have downloaded IMERG V06A Data previously, please discard this data and use the improved IMERG V06B products as they are produced and archived.
All IMERG V06A Final products will be retracted later today.
On Wednesday, June 5, PPS will start the V06B reprocessing beginning with the GPM era, June 2014 - current available data. Once the GPM era is completed, PPS will start the TRMM-era, June 2000 - May 2014.
Due to capacity loads at PPS, there are no firm estimates as to how long this will take.
V06A is being retracted due to a corrupt surface coverage file in the Kalman statistics computation.
Please contact us for any questions.
A damaged land/ocean mask file (specifically, a several-gridbox shift to the east and south) has been discovered in IMERG V06A, which causes mis-identification of surface type along coasts in the Kalman filter computation. While simple to correct, the change in the IMERG results requires shifting to a new sub-version. As of May 22, the Early and Late Run files have the corrected land/ocean mask file and are labelled V06B. The adjustment will be seen in the Early and Late data files starting June 1, when the next Kalman statistics are computed.
PPS will be updating GPM 1AGMI data from V05A to V05B today, Thursday May 09, 2019 because there was a minor bug in the algorithm. Only 1AGMI will change versions.
The L1AGMI executable was previously not filling in a missing scan if there was an error in reading or processing the scan data from the instrument. Nothing was being generated in the GMI 1A product in this case. The bug fix was to fill in a missing scan and annotate this in the file header.
On 1 May 2019, at approximately 14 UTC, PPS will stop production of IMERG V05 in order to setup and install the new IMERG V06 code for production of early and late products.
This will require an extended period when no IMERG products will be produced or available for users. We estimate an extended period of IMERG unavailability that may last for 5 hours or more.
Upon resumption of IMERG production, V06 will start with data from 1 May
2019 hour 00 UTC. We will reestablish latency of early products to 4 hours, and late products to 14 hours, as soon as possible.
An error has been discovered in processing the initial batches of V06 IMERG Final Run months. A design choice in the code ended up retaining microwave precipitation estimates in the latitude band 60°N-S when there is snow/ice on the surface, rather than masking out the estimates due to low performance in such cases. [Masking for microwave retrievals over surface snow and ice outside that band is correct.]
Starting this week (Wednesday March 13, 2019 or soon after) PPS will commence GPM IMERG data reprocessing for IMERG V06. PPS will start reprocessing with the GPM-era data and will make these products available as they are archived.
Thereafter, we will reprocess the TRMM-era data. The first available products for the GPM-era will start with June 2014. TRMM-era products will span June 2000 - May 2014. Earlier TRMM-era processing, 1998-01 to 2000-05, will proceed when all required input data have been provided.