# Presentation: 534421

## Process-Scale Modeling of ASP Field measurements

*V. Rao Kotamarthi*
*Environmental Research, ANL*

## Motivation For The Study

**Coupled models of the atmospheric chemistry-aerosol dynamics-atmospheric dynamics are needed to fully evaluate measurements of aerosols and their precursors during intensive field campaigns. **
**Intensive field campaigns focused primarily on urban and mega city generated aerosols and their impacts on direct and indirect radiative effects will be conducted over the next few years. **
**The goal of these experiments would be to:**
- Collect data on the aging of the aerosols
- Measure aerosol optical properties as a function of age
- Measure the chemical composition of aerosols as a function of age
- Characterize the lifetime (mainly washout lifetimes) of selected aerosols
- Aerosol vertical distribution in and around a mega city.

## 0.0 – 2.0 km

**0.0 – 2.0 km**

**2.0 – 4.0 km**

**4.0 – 6.0 km**

## Refractive index    1.56 + .005i     (Russell et al., 1997)

**Refractive index    1.56 + .005i     **(Russell et al., 1997)

**Refractive index    1.56 + .025i**     (Wong and Li, 2002)

## Aerosol Optical Depth

**t = ****∫ (****C****ext * ****N****) dz                  ****(Liou, 1992)**
**	****C****ext = average extinction cross section per ****	****   particle **
**	****N = particle density (# / m****3)**
**dN/dlogr = A r****^(****(1-3b) / b)****) ****exp(- ****r / ab****)**
**               ****where 0 < b < 0.5    (Mishchenko et al., 1999)**
**	****A = constant**
**	****r = mean radius**
**	****a = coefficient**
**	**

| t = .012 |
| --- |
| t = .018 |
| t = .189 |
| t = .060 |
| t = .074 |
| t = .076 |
| t = .086 |
| t = .115 |
| t = .119 |
| t = .185 |
| t = .282 |
| t = .340 |

- 0.0 km

- 0.5 km

- 1.0 km

- 1.5 km

- 2.0 km

- 2.5 km

- 3.0 km

- 3.5 km

- 4.0 km

- 4.5 km

- 5.0 km

- 5.5 km

- 6.0 km

**0-6km AOD for MRI = .005 at ****λ**** = .55****μ****m**

## Argonne 1-D PBL Dynamics-Aerosol Model

**Soil surface temperature calculated using force restore method**

**Top = 3000 m**

**Velocities calculated at grid box**
**edge, all other quantities at the**
**box center**

**UV Photolysis rates calculated using an online  two stream radiation model/FAST J**

**Parameterized longwave and short wave radiation for surface temperature calculations**

**Argonne 1-D PBL Dynamics-Aerosol Model**

**79 Trace gases**
**~250 Thermal Reactions**
**~30 Photolysis reactions**
**~5 heterogeneous surface reactions**

** ****K- ******** Model for PBL Dynamics**
**gives 2.5 level closure**

**Fluxes{ <wc>}  calculated at box edges**

**MAD/SORGAM Aerosol Scheme**
**Three size modes, 28 distinct **
**aerosols**

## Aerosol Package

**The aerosol module for the column model is adopted from the CMAQ model (MAD-SORGAM)**
**The aerosol code represents aerosol size distributions as three different size modes (Aitken, accumulation, and coarse), with a log-normal function describing the size distribution in each mode.**
**The SORGAM code represents the formation of semivolatile organic compounds and their gas-particle partitioning (Schell et al. 2001).**
**The chemical composition of inorganic aerosols in the atmosphere, especially those containing nitrate and sulfate is calculated by assuming an instantaneous thermodynamic equilibrium between the gas and the particle phases using ISORROPIA (Nenes et al. 1999) thermodynamic model.**

## Preliminary Results

## Preliminary Results 

## MM5/WRF

**Optical Properties**
**Calculated with Mie codes and **
**Look-up tables**

- Coupled Model For Regional Climate - Aerosols

- offline

**Flux Coupler**
**Dynamic input from WRF to**
** ****CMAQ;**
**Aerosol output from CMAQ**
** ****to WRF**

**CMAQ Aerosol Process and **
**Transport Model**

**Postprocessor for**
**MM5/Preprocessor for **
**CMAQ**

**RRTM/ Shortwave code**

- offline

## pNetCDF

**Notes:**
Efficiency = Time on one processor/(no of processors x time on p processors)

## Conclusions

**The planned ASP field experiments require process-scale models to evaluate measurements of aerosols and related processes.**
**Models ranging from 0-D box models to evaluate gas-to-aerosols conversion rates, 1-D models to evaluate vertical distribution, deposition  and cloud interactions to regional scale models are needed.**
**We have converted our 0-D and column photochemical models to include aerosol module from CMAQ.**
**The column model will need to be integrated with radiation models in the near future.**
**The regional scale model for performing coupled and online calculations of   aerosols and their effect on radiation is under development. **

## Acknowledgements

**Melissa Melvin, DOE SURE student, 2004, ANL and currently graduate student ****at the Nebraska-Lincoln School of Natural Resources.**
**Rob Latham, Mike Dvorak and Peter Schmitt of the MCS at ANL.**
**CMAQ maintainers and Developers**