Community Modeling and Analysis System

Research and Development

Ongoing Research and Development | Model Development Guidelines

CMAS is keen on providing updates of current research efforts engaged by members of the community on the development and analysis of air quality modeling systems, including meteorology and emissions processing models. Research is focused on efforts to enhance the capability of air quality modeling systems to adequately address existing and future National Ambient Air Quality Standards (NAAQS). CMAS will provide leadership to bridge the gap between research and application needs by coordinating efforts among members of the community. Eventually, these research topics will lead to new research versions of CMAQ. Upon receiving new modules from the developers, CMAS will review the computational performance of the developed version and compare it to a benchmark case study provided by the developer to ensure accuracy, compilation, and compatibility among various computational platforms. CMAS will also review documentation that is provided by developers of the new material. CMAS will acknowledge the contribution of the developers of various modules.

CMAQ Review Process

Ongoing Research and Development

CMAS wants to hear about your CMAS-related research and/or model development! Please take a moment to provide us with some brief information about your CMAS-related research and/or model development, and we will post that information below. We also want your feedback on developing a vision for the next generation air quality modeling systems. Click on a title below to read more about the research.

  1. Efficient Radiative Transfer Calculations for Photolysis in CMAQ
  2. Extensions to chemically active coarse mode: Incorporation of sea-salt aerosols
  3. Incorporation of the Pleim-Xiu (PX) land surface model into the Weather Research and Forecasting (WRF) model

Efficient Radiative Transfer Calculations for Photolysis in CMAQ

The overall objective of this task is to implement the fast TUV code in CMAQ. The current version of TUV has a subroutine (setaer) to calculate the effects of aerosol particles on the photolysis rates. This routine uses background information on aerosol optical depth along with constant values for single scattering albedo and asymmetry factor. This task will replace them with a very efficient approach.

This work will build upon the visual range calculations in CMAQ ( Binkowski and Roselle, 2003). The method will use the same very accurate approximation to Mie extinction efficiency as used in CMAQ along with an analogous approximation to absorption efficiency. These efficiencies will be integrated over the lognormal modes as is currently done in CMAQ. The difference will be that whilst the visibility calculation in CMAQ is done at 550 nm, the new calculations will be done over a series of wavelengths appropriate to photolysis. Scattering will be obtained from the difference between extinction and absorption. This is a numerically favorable method because most particles other than carbon soot are weakly absorbing. Even for carbon soot, this approach will yield good results. An empirical function based upon the ratio of particle scattering to molecular scattering will provide the asymmetry factor. All of these approximations will be compared to actual Mie calculations to assess their accuracy. A further study will be done to evaluate a parameterization based upon an analytical representation of the integral of the extinction and absorption over the size distribution. This last method will be very inexpensive.

Model Development Guidelines

CMAS has compiled a set of guidelines for new code development, based on experience with portability testing of the CMAQ-MADRID code, developed by AER under an EPRI contract. The code has just been released in stand-alone mode (April 2004). Download instructions are available through Software Downloads.

For more information about research opportunities in conjunction with the CMAS Center, please contact Sarav Arunachalam, CMAS Modeling Research Coordinator.