AirWare User Manual: MM5-CAMx coupling

AirWare On-line Reference Manual

Release Level 5.4
Release Date 2008 10

Revision Level 1.0

Last modified on: Monday, 20-Jul-09 14:03 CEST

Coupling of MM5 with CAMx

Coversion of meteorological fields computed with MM5 to CAMx inputs is done using MM5CAMx post-processing program (Reference:http://www.camx.com/down/support.php). The program is written to assume hourly MM5 output and generates hourly CAMx inputs. Horizontal interpolation gives option to interpolate MM5 output on the CAMx grid defined on a UTM projection of any resolution, as long as it fits within the area defined by outer rows/columns of MM5 "cross" points. MM5CAMx interpolates all needed variables to CAMx grid cell centers.

The CAMx physical height layer structure (meters AGL) is defined from the MM5 sigma-p layer structure, and thus varies in space. Vertical averaging of MM5 layers to a coarser CAMx layer structure is allowed. The set of MM5 layers to combine into CAMx layers is specified in the script file. Variables in each MM5 layer are mass-weighted to each bulk CAMx layer.

The 4D meteorological fields for CAMx provided from MM5 output are:

CAMx Z-P file	CAMx height/pressure input file
CAMx Wind file	CAMx u, v wind components input file
CAMx Temp file	CAMx temperature input file
CAMx Kv file	CAMx vertical diffusivity input file
CAMx Water file	CAMx vapour input file
CAMx Cld/rain file	CAMx cloud/rain input file

The MM5 output file ( MMOUT_DOMAIN ) file for one day for the DOMAIN specified in mm5grid.txt must be present.

For a single day, 25 hours of meteorology must be present (midnight through midnight, inclusive) as these fields represent hourly instantaneous conditions and CAMx internally time-interpolates these fields to each model time step. Longer simulatiopn/forecast periods are implemented as a sequence of 24 hour days.

Please note that the vertical discretization resolution using in each application is described in the respective Installation Notes.