This module, part of the "NWP Training Series: Effective Use of NWP in the Forecast Process", describes model parameterizations of surface, PBL, and free atmospheric processes, such as surface snow processes, soil thermal and moisture processes, surface vegetation effects such as evapotranspiration, radiative processes involving clouds and trace gases, and turbulent processes in the PBL and free atmosphere. It specifically addresses how models treat these processes, how such processes can potentially interact with each other, and how they can influence forecasts of sensible weather elements.
Back in 2000, the subject matter expert for this module was Dr. Ralph Petersen of the National Centers for Environmental Prediction, Environmental Modeling Center (NCEP/EMC). Revisions to the module were made in 2009 by Drs. Bill Bua and Stephen Jascourt, from the NWP team at UCAR/COMET.
After completing this module, you should be able to:
1. Identify effects that are smaller than NWP models can emulate (e.g. variations in surface characteristics that are smaller-scale than the NWP model resolution).
2. Cite situations where physical processes are important to the model forecast relative to dynamical processes.
3. State how basic radiative transfer processes are parameterized in NWP models.
4. State what situations various physical parameterizations will work well, and those where they will work poorly.
5. Cite situations in which at least two physical parameterizations will interact with each other, and the potential feedback effects.
6. Identify at least one consequence of errors in model physics on model forecasts at and around a forecast location.
December 2020 - The lesson was updated to current internet standards (mp4/html5), with no changes to content.
July 2014: Version 2 of the NWP course is still valid throughout. The most recent data assimilation system used in NCEP models, the Hybrid-EnKF, is not included. This data assimilation system combines 3D-VAR and EnKF into a single system and gets advantages from both. More discussion of the Hybrid-EnKF system can be found in the GFS May 2012 "splash' announcement at http://www.meted.ucar.edu/nwp/pcu2/GFS_20120522_HybEnKF3DVAR.htm.
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