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Recent DAS Modifications

GEOS - 5

An updated version of the File Spec (V1.0) for GEOS-5 DAS Gridded Output has been published. Version 0.1 is also available below for your reference.

The File Spec is available in:

V1.0 PDF or V1.0 WORD (version 6.3, Sep.2007)

V0.1 PDF or V0.1 WORD (version 6.1, Oct.2006)

Less Recent DAS Modifications that may still be of some interest

GEOS - 4 DAS

Operational on Data Date 10/1/02 for both First Look and Late Look.

Beginning data date 5/1/03, GEOS-4 was upgraded to resolve anomalous noise in the skin temperature and near surface temperature and humidity fields. This upgrade, 4.0.2, was promoted to operations on this data date for both First Look and Late Look.

Beginning data date 1/15/04, GEOS-4 was upgraded to include the following modifications:

1. New Land Model
2. Improvements to Skin Temperature analysis
3. NOAA-17 satellite assimilation
4. MODIS cloud track winds assimilation over the poles
5. Relative Humidity fix near surface
6. Diag wind output stream for stratospheric transport customers

Beginning data date 7/14/04, the Ozone Assimilation System for GEOS-4 was modified. The chemistry model was modified to include changes in the ozone production rates in the upper-stratosphere. Ozone chemical equilibrium (the quotient between production and loss rates)now agrees with the extended UARS ozone climatology. In the previous system the chemical equilibrium agreed with the climatology by Langematz (Geophys. Res. Lett., 27, 2077-2080, 2000). The new rates will have a direct impact on ozone in the upper stratosphere. The change was made because ozone in the previous system near 2 hPa in the winter high latitudes was excessive in comparison with independent POAM profiles.

Beginning data date 8/20/04, a corrective patch was made to GEOS-4 for both FLK and LLK to address excessive relative humidities and excessive near surface temperature increments in regions of the globe having large near surface temperature inversions.

MODIS Wind data from NESDIS began to be assimilated by LLK on data date 9/29/04 and by FLK on 10/14/04

NOAA-14 TOVS Level 1B data began to be assimilated by LLK on data date 1/11/05, by FLK on 2/22/05 @ 0Z and by CERES 01 Forward Processing on data date 1/10/05. Along with other NOAA-16 data users, we had experienced increasing noise in both HIRS and AMSUA channels from NOAA-16. Experiments showed a reduction in this noise with the inclusion of NOAA-14 data. Further efforts to reduce this noise in FLK included removing NOAA-16 channels 39-44 for the period 1/20/05 (12Z) thru 2/01/05 (0Z).

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