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Community Multiscale Air Quality Modeling System (CMAQ)

Meteorology - Chemistry Interface Processor

MCIP Overview

The Meteorology-Chemistry Interface Processor (MCIP) ingests output from the Weather Research and Forecasting (WRF) Model to prepare the meteorology files that are used within the CMAQ Modeling System. Where possible, MCIP uses data directly from the meteorological model to maximize consistency with the CMAQ Modeling System. When specific atmospheric fields are not explicitly output by WRF, MCIP uses scientific algorithms to create those fields for CMAQ.  MCIP output is used by the emissions model (for example, to provide time-varying temperatures for mobile emissions) and by the CCTM to define the atmospheric conditions. As of MCIPv5.0, WRF is the only meteorological model that can be processed with MCIP, but MCIP could be expanded to process data from other meteorological models.  A scientific overview of MCIP is in Otte and Pleim (2010).

MCIP performs the following functions using the output (history) file from WRF:

  • Defines the computational domain for the CCTM. The CCTM typically uses a smaller computational domain than the meteorological model, and the lateral boundary cells from the meteorological model generally are not used by CCTM.
  •  Extracts meteorological model output on the computational domain that is prescribed for the CCTM.
  • Processes all required meteorological fields for the emissions model and the CCTM. Meteorological fields such as atmospheric temperature, pressure, humidity, and winds are acquired directly from the meteorological model (i.e., "passed through").
  • Uses the available meteorological fields to compute additional fields that are required by the CCTM but are not part of the meteorological model's output stream, such as the Jacobian which is used for coordinate transformations.
  • Outputs files that contain meteorological and geospatial information used by the emissions model and the CCTM.  The output can be either in I/O API or netCDF.

Previous MCIP Versions

MCIPv4.3 and MCIPv4.2 were released via the CMASCenter MCIP GitHub repository.  Beginning with version 4.5, MCIP is released as part of the CMAQ repository.  

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Related Links


Otte, T.L., Pleim, J.E., The Meteorology-Chemistry Interface Processor (MCIP) for the CMAQ modeling system: updates through MCIPv3.4.1, Geoscientific Model Development,, 2010.