CMAQv5.5 Series FAQ

Frequently Asked Questions for Upgrading to the Latest CMAQ Version

Table of Contents:

• Do I need to update from v5.4 to v5.5?
• What do I need to do to update from v5.4 to v5.5?
  • What differences should I expect in the required model input files?
  • What differences should I expect in my model output files?
• What differences should I expect in my model results with v5.5 compared to v5.4?
• Additional FAQ
• Technical support for CMAQ

Do I need to update from v5.4 to v5.5?

CMAQv5.5 includes many scientific enhancements and new features that will benefit certain applications. See the v5.5 Release Notes for a description of each change.

Instrumented Models

• Several updates were incorporated in CMAQ-ISAM: (1) accounting for the loss of aerosol mass from gravitational settling was incorporated, so that the tagged and bulk concentrations matched more precisely; (2) a new tag was incorporated to attribute O3 to be of “stratospheric origin” based on the PV-scaling methodology; (3) addressed instabilities associated with mass distribution between tags immediately after cloud chemistry. See: CMAQ-ISAM Release Notes for more information.

• In CMAQ-DDM: (1) enabled estimation of sensitivity of O3 to PV-O3 specification; (2) corrected calculation of second-order sensitivity in chemistry routines; (3) corrected error that caused incorrect dry deposition sensitivity in output. See CMAQ-DDM Release Notes for more information.

• Fixes to Sulfur Tracking Model (STM) correct errors in attribution of sulfate from gas phase chemistry, which inadvertently got introduced in the previous model version. See CMAQ-STM Release Notes for more information.

WRF-CMAQ Coupled Model

• Coupled WRF-CMAQv5.5 (Wong et al., 2010) is compatible with WRF versions 4.4 to 4.5.1. EPA's testing of WRF-CMAQ has included chemical mechanisms CB6r5 and CRACMMv1 with the M3DRY dry deposition scheme. Other model options can be used with the WRF-CMAQ model but will have limited user support for issues that are encountered.

Chemistry

Dry Deposition/Air Surface Exchange

Emissions

Process Analysis

Structural Improvements

Diagnostic Options

Pre-processors and Utilities

Post-processors

Utilities

What do I need to do to update from v5.4 to v5.5?

What differences should I expect in the required model input files?

What differences should I expect in my model output files?

What differences should I expect in my model results with v5.5 compared to v5.4?

Natural Emissions

Ozone

• Summary:

PM2.5

• Summary:

Deposition

• Summary:

Additional FAQ

A more general list of Frequent CMAQ Questions can be found on our website: https://www.epa.gov/cmaq/frequent-cmaq-questions

Technical support for CMAQ

Technical support for CMAQ, including questions about model inputs, downloading, compiling, and running the model, and pre- and post-processing utilities, should be directed to the CMAS Center User Forum. Please read and follow these steps prior to submitting new questions to the User Forum.