Mesoscale Parallel Experiment Log

Experiment Name

Eta-32 with GOES cloud top pressure assimilation

Parallel Slot

ETAY

Control Slot

ETAZ

Start date of parallel experiment

12Z 2002/06/25

End date of parallel experiment

00Z 2002/07/09

Environmental Modeling Center scientists

Ying Lin, Jim Jung (NESDIS), Geoff DiMego, Brad Ferrier, Eric Rogers

Abstract

The Eta-32 is being used to test assimation of GOES-8/10 cloud top pressure data in the EDAS
FORECAST MODEL CHANGES

Prior to running each 3-hour EDAS segment, a pre-processing program reads in the 3-hour's worth of GOES cloud top data from the PREPBUFR file, and distributes the observations to the appropriate assimilation hour and horizontal Eta grid box.

During EDAS, at each physics time step and on each Eta grid where observed cloud top is available, we zero out model cloud water/cloud ice above the observed cloud top, and set the water vapor mixing ratio to no more than saturation (original value or grid-scale saturation value [w/r/t water if T > -10 C, otherwise w/r/t ice], whichever is less). At the model level closest to the observed cloud top, if the model air is sub-saturated (by an amount of delta(Qv)), the air at this level is then moistened by the amount of delta(Qv)*physDT/3600., i.e. it is moistened at a rate that would bring it to saturation in 1 hour.

The observed cloud top is also used as 'anchor' cloud top in precipitation assimilation, i.e. in the event that we need to create a layer of precipitating cloud, the observed cloud top is used in the cloud creation.

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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