GEOS Forward Processing (GEOS-FP) Upgrade Feb 7, 2023


The GMAO upgraded the GEOS Forward Processing (GEOS FP) system, from GEOS-5.27.1 to GEOS-5.29.4 starting with the 06:00 UTC cycle on Tuesday, March 1, 2022.

GEOS-FP will be upgraded to GEOS-5.29.5 on February 7, 2023 with the 06:00 UTC assimilation cycle. There are no changes to the file formats documented in the GEOS-FP File Specification or access methods via the NCCS Data Portal with this upgrade. There may be some delay in producing and posting the 06:00 UTC assimilation data, but the 12:00 UTC forecast cycle is expected to start at the normal time.

Version 5.29.5 of the GEOS atmospheric data assimilation system includes a limited number of updates to both the analysis scheme and forecast model. In the analysis, commercially produced radio occultations from SPIRE are now assimilated, sourced from NOAA’s real-time commercial data purchase. This brings the total number of radio occultations assimilated in each 6-hr analysis cycle to approximately 450,000 on average, or an increase of roughly 45% compared with version 5.29.4 of the GEOS system. Also in the analysis, the maximum height for assimilation of (all) radio occultation data has been lowered from 60 km to 55 km, for better consistency with the vertical discretization of the model. Finally, an information data base has been introduced to control changes in the availability and usage of conventional observations (similar to the method used for satellite radiances) but this is a zero-difference change. In the forecast model, the orbital parameters used in the radiation scheme have been updated, which yields only a minor change in the model solution.

Overall, these updates provide a neutral to small positive impact on the GEOS analysis and short-term forecast performance, as revealed by traditional skill-scores and estimates of analysis errors for wind, temperature and specific humidity, with the largest impacts observed in the tropical middle troposphere. The impact is due primarily to the assimilation of the additional radio occultation data.

More information about GEOS real-time products, including the current GEOS FP File Specification document, can be found at this link:

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