Fast, Jerome, Vinoj Velu, Ying Liu, and Manish
Shrivastava, Pacific Northwest National Laboratory
The WRF-Chem model is
used to simulate the evolution of carbonaceous and inorganic aerosols and their
impact on radiation during May and June of 2010 over California when two field
campaigns took place (CalNex and CARES).
We have merged the CalNex and CARES data into a common dataset for the
Aerosol Modeling Testbed, which is supplemented with operational data from
various networks. The resulting
rich dataset is used to evaluate how well the model simulates aerosol
properties needed to understand uncertainties that could affect regional
variations in radiative forcing.
The model reproduced many of the diurnal, multi-day, and spatial
variations of aerosols as seen in the measurements; however, performance varied
over California and some aerosol species are better represented than
others. The simulated backscatter
and extinction compared well to observed profiles from the High Spectral
Resolution Lidar, although the values in the boundary layer were too high at
times and free tropospheric values were consistently higher than observed
suggesting that long-range transport was too large. Consistent with the Lidar comparisons, simulated aerosol
optical depth was often too high.
Finally, the impact of the simulated aerosols on radiation will be
quantified in relation to the uncertainties in predicted aerosol properties.