GEOS FP Upgrade Planned for 25 February, 2021


NOW Rescheduled: GEOS FP Upgrade Planned for 25 Februa

GEOS-FP users,

The GMAO will be upgrading the GEOS Forward Processing (GEOS FP) system, from GEOS-5.25.1-p5 to GEOS-5.27.1, starting with the 06:00 UTC cycle on Thursday February 25, 2021.

This upgrade will not result in any changes to products documented in the GEOS FP File Specification, which is available at the link included at the bottom of this notice. Formats and access methods for GEOS FP will remain the same.

Version 5.27.1 of the GEOS atmospheric data assimilation system includes significant updates to the GSI analysis code plus numerous additions to the input observing system. There are no significant changes to the GEOS model in this update.

The updated GSI code is a merged version of the latest NCEP and GMAO code bases. Active new features include variational bias correction of aircraft temperature observations, modified observation operator for GNSS RO (radio occultation) data, a reformulated atmosphere-ocean interface layer suitable for coupled model applications, and reformatted diagnostic output to facilitate development of a future (JEDI-based) version of the assimilation system.

Updates to the input observing system include the assimilation all-sky radiances from MHS (all platforms) and GCOM-W AMSR-2 (over water only). The AMSR-2 radiances are new to GEOS, while the MHS radiances were previously assimilated in clear-sky conditions only. Ozone-sensitive radiances are assimilated for all hyperspectral infrared instruments. Observations from the Metop-C satellite are assimilated, including radiances from AMSU-A and MHS, plus radio occultations from GRAS. CrIS full spectral resolution (FSR) radiances from SNPP and NOAA-20 are assimilated (over water only), with channel-correlated observation errors. Finally, radio occultations from the COSMIC-2 constellation of (six) satellites are assimilated.

Overall, these updates provide measurable positive impact on various aspects of the GEOS analysis and forecast performance. These include improved background forecast fits to radiosonde observations in the middle and upper troposphere, improved fits to many microwave and infrared satellite sounding channels, and improved representation of large-scale ozone patterns in the troposphere. Forecasts of tropospheric wind and temperature are generally improved globally, and forecasts of humidity are improved especially in the lower tropical troposphere. The background fits to radio occultation data are degraded at some levels, but this does not have any noticeable reflection on the analyzed temperature and humidity profiles.

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

Please let us know if you have any questions or concerns.

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