Author(s)

RENE PARRA

Abstract

Microphysics schemes resolve cloud processes that occur on the scales of the cloud droplets, affecting precipitation, radiation and surface energy budgets, therefore influencing atmospheric and air quality modelling. Working with a spatial resolution of 1 km, we investigated the impact of microphysics options coded in the Weather Research and Forecasting with Chemistry (WRF-Chem) model version 3.2 for modelling weather and air quality variables during September 2014 in Cuenca (2500 masl), an Andean city in southern Ecuador. We considered nine options: 1 Kessler, 2 Purdue Lin, 3 WSM3, 4 WSM5, 5 WSM6, 6 Eta GCP, 7 Thompson, 8 Goddard and 10 Morrison 2-Moment. The cumulus option was deactivated, and direct effects between aerosols and atmospheric variables were considered. The CBMZ and the MOSAIC mechanisms were used to speciate the hourly emissions from the 2014 Cuenca emission inventory. Data for comparison with modelled quantities were recorded at stations located over the urban area, belonging to the city’s air quality network. The 3 WSM3, 6 ETA GCP and 2 Purdue Lin microphysics options collectively demonstrated better performance in modelling both weather and air quality variables. Although all the options correctly modelled surface temperature and wind speed, the performance for wind direction was fair and solar radiation at the surface was overestimated for all schemes, capturing between 70% and 78% of the days, regardless of whether rainfall was present or not. Updated WRF-Chem versions and new schemes should be assessed, or even the development of a dedicated option is required to improve the modelling of processes associated with microphysics over the tropical Andean region.

Keywords

Cuenca, direct effects, one atmosphere, configuration, atmospheric modelling