GEOS FP to be Updated on April 7, 2020


GEOS-FP users,

On January 30, 2020, GMAO upgraded GEOS-FP to GEOS-5.25.1-p3. The GMAO is announcing an update to this system, GEOS-5.25.1-p5, to be implemented at 06:00 UTC on April 7, 2020. This new update introduces two changes to the GEOS model that are needed to rectify deficiencies detected in the 5.25.1-p3 version of the GEOS-FP system. There are no changes to the file specification or data access methods for GEOS-FP data.

The first change is an update of the RRTMG-SW code to v4.10 from the developers at Atmospheric and Environmental Research (AER). This update addresses a cold bias of up to ~2K°/day in the heating tendency in the stratosphere, between 10-0.1mb, peaking at 1mb in the Tropics and summer hemisphere. The AER developers have provided an update to the correlated k-Distribution (CKD) for band 28 (~ 200-263 nm), in which both ozone and molecular oxygen are significant absorbers. This change significantly reduces the underestimate in solar heating rates that lead to this cold bias in the temperature analyses and forecasts.

The second change is to the Grell-Freitas deep convection code. It addresses errors in the convective mass flux diagnostics which have downstream impacts on moist processes and transport in the GEOS-FP system. These patches resolve an underestimation of cloud ice in the tropical upper troposphere and associated errors in outgoing longwave radiation comparisons with CERES-EBAF. Another patch to the Grell-Freitas code corrects an evaporation-check bug introduced in the previous GEOS-FP system: this bug fix results in improved extratropical skill scores for heights in the mid-troposphere.

More information about GEOS real-time products can be found at this link:

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