P42  A WRF/Chem Ozone Sensitivity Study using Ensemble Modeling for Slovenia and Northern Adriatic Area

Zabkar, Rahela and Joze Rakovec, University of Ljubljana and Center of Excellence SPACESI; Darko Koracin, Desert Research Institute, Reno

In the present work results of an extensive tropospheric ozone sensitivity modelling study performed using the WRF/Chem model as part of the research activities related to the recently implemented operational ozone forecast in Slovenia, are presented. The motivation came from results of a previous work focused on the roles of regional vs. local emission sources on ozone levels in Slovenia. During the high ozone episodes in Slovenia the main dynamic characteristics of episodes were generally well simulated, but some significant discrepancies between simulated and measured ozone and basic meteorological variables were common to all analyzed high ozone episodes, including underestimation of daytime ozone levels in Slovenian coastal areas and overestimation of nighttime ozone levels at some stations.

The aim of the present study is: (1) to investigate the previously observed model systematic errors in simulated ozone levels, (2) to explore ability of different WRF physics parameterization schemes to accurately simulate meteorological conditions typical of high ozone episodes over a region of the geographically complex northeastern Mediterranean Basin, and (3) to investigate the sensitivity results of simulated ozone levels due to the main sources of model uncertainties (meteorological boundary layer processes, anthropogenic and biogenic emissions, lateral and initial chemical boundary conditions).  To accomplish the study goals, more than 50 experimental ensemble simulations were performed for an episode that was highly favorable for ozone formation. The experimental runs consisted of different WRF model physical parameterizations, including different planetary boundary layer, land surface model, surface layer, radiation schemes, and with improved sea surface temperature. In addition, some tests regarding other major sources of model uncertainties (e.g., biogenic and anthropogenic emissions, their temporal variations, and chemical boundary conditions) were also included in the ensemble runs to examine the influence of these uncertainties on model results.