Mesoscale Parallel Experiment Log

Experiment Name

Eta-32 with assimilation of merged Stage II/Stage IV precipitation analyses

Parallel Slot

ETAL

Control Slot

ETAV

Start date of parallel experiment

12Z 2002/11/19

End date of parallel experiment

12Z 2003/01/13

Environmental Modeling Center scientists

Ying Lin, Eric Rogers

Abstract (including Motivation, Hypothesis and Method)

The 32-km EDAS/Eta parallel system is being used to test the assimilation of the merged Stage II/IV precipitation analysis.
ANALYSIS CHANGES

Since its implementation in July 2001, the ETA/EDAS precipitation assimilation uses the NCEP Stage II hourly precipitation analysis as the source of observed precipitation. Another hourly precipitation analysis now available is the NCEP Stage IV analysis, which is a mosaicked product based on the regional multi-sensor precipitation analyses produced by the 12 CONUS River Forecast Centers. Both analyses are based on hourly radar and gauge observations, Stage IV benefits from some manual quality control at the RFCs, while the Stage II, produced directly at NCEP from hourly radar/gauge data, are more timely.

For this experiment, both Stage II and Stage IV are used in the Eta/EDAS precipitation analysis. Since Stage IV is generally considered to be of higher quality, during the data-preparation stage prior to running each EDAS segment, we merge the two analyses as outlined below. For each hour that will be covered by the upcoming EDAS segment, we use the available Stage IV analysis as the primary data source, and fill in any missing-data area in the Stage IV analysis (individual RFCs send out their hourly analyses at different times through out the day, so at the time the data is needed by the Eta model, the Stage IV coverage might not be complete. Please see the Q&A for more details about the timeliness of the Stage IV) with the available Stage II.

An example of the merged product can be found at http://www.emc.ncep.noaa.gov/mmb/ylin/merge2n4/.

Experiment changes log

Background links

Evaluation of parallel results

Daily forecast maps

Daily forecast stats

Verification of precipitation and against rawinsondes / surface data

Conclusion

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