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A Linearized Prognostic Cloud Scheme in NASAs Goddard Earth Observing System Data Assimilation ToolsA linearized prognostic cloud scheme has been developed to accompany the linearized convection scheme recently implemented in NASA's Goddard Earth Observing System data assimilation tools. The linearization, developed from the nonlinear cloud scheme, treats cloud variables prognostically so they are subject to linearized advection, diffusion, generation, and evaporation. Four linearized cloud variables are modeled, the ice and water phases of clouds generated by large-scale condensation and, separately, by detraining convection. For each species the scheme models their sources, sublimation, evaporation, and autoconversion. Large-scale, anvil and convective species of precipitation are modeled and evaporated. The cloud scheme exhibits linearity and realistic perturbation growth, except around the generation of clouds through large-scale condensation. Discontinuities and steep gradients are widely used here and severe problems occur in the calculation of cloud fraction. For data assimilation applications this poor behavior is controlled by replacing this part of the scheme with a perturbation model. For observation impacts, where efficiency is less of a concern, a filtering is developed that examines the Jacobian. The replacement scheme is only invoked if Jacobian elements or eigenvalues violate a series of tuned constants. The linearized prognostic cloud scheme is tested by comparing the linear and nonlinear perturbation trajectories for 6-, 12-, and 24-h forecast times. The tangent linear model performs well and perturbations of clouds are well captured for the lead times of interest.
Document ID
20150023394
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Holdaway, Daniel
(Universities Space Research Association Greenbelt, MD, United States)
Errico, Ronald M.
(Morgan State Univ. Baltimore, MD, United States)
Gelaro, Ronald
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Kim, Jong G.
(Science Systems and Applications, Inc. Lanham, MD, United States)
Mahajan, Rahul
(Oak Ridge Associated Universities, Inc. Oak Ridge, TN, United States)
Date Acquired
December 18, 2015
Publication Date
October 1, 2015
Publication Information
Publication: Monthly Weather Review
Publisher: American Meteorological Society
Volume: 143
Issue: 10
Subject Category
Meteorology And Climatology
Report/Patent Number
GSFC-E-DAA-TN28220
Funding Number(s)
CONTRACT_GRANT: NNG11HP16A
CONTRACT_GRANT: NNG12HP06C
Distribution Limits
Public
Copyright
Other
Keywords
Precipitation
Large-scale condensation
Linearized Advection

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