P34  WRF-Chem Model Evaluation over the Rocky Mountains Forest during the BEACHON-RoMBAS 2011 Field Study

Hodzic Roux, Alma, David Gochis, National Center for Atmospheric Research

The scientiÞc understanding of the formation and aging of organic aerosols in forest environments is still limited. The Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen (BEACHON)-RoMBAS intensive aerosol study took place from 25 July to 25 August 2011 at the Manitou Observatory Forest in Colorado with the speciÞc objective of characterizing the formation of biogenic particles in the forest canopy, and quantifying the perturbations that occur in presence of anthropogenic emissions. Here we present the results of the high-resolution simulations (4km) that were performed over the Colorado mountains using the WRF-Chem model during summer 2011. The aerosols were simulated using the MOSAIC aerosol model with updated SOA yields and NO3 chemistry. The meteorological and passive tracer analyses were performed to identify the main circulation patterns and periods featuring the transport of the front-range urban pollution over the forest site. For each of these periods the WRF-Chem model predictions of main organic aerosol components were assessed and compared with the AMS data. The role of NOx in SOA formation is discussed. In addition, the sensitivity of the model results to changes in the landuse were assessed by comparing the results between MODIS and USGS landuse types.