Sensitivity Study of Cloud Cover and Ozone Modeling to Microphysics Parameterization

Abstract

Abstract-Cloud cover is a significant meteorological parameter influencing the amount of solar radiation reaching the ground surface, and therefore affecting the formation of photochemical pollutants, most of all tropospheric ozone (O 3 ). Because cloud amount and type in meteorological models are resolved by microphysics schemes, adjusting this parameterization is a major factor determining the accuracy of the results. However, verification of cloud cover simulations based on surface data is difficult and yields significant errors. Current meteorological satellite programs provide many high-resolution cloud products, which can be used to verify numerical models. In this study, the Weather Research and Forecasting model (WRF) has been applied for the area of Poland for an episode of June 17th-July 4th, 2008, when high ground-level ozone concentrations were observed. Four simulations were performed, each with a different microphysics parameterization: Purdue Lin, Eta Ferrier, WRF Single-Moment 6-class, and Morrison Double-Moment scheme. The results were then evaluated based on cloud mask satellite images derived from SEVIRI data. Meteorological variables and O 3 concentrations were also evaluated. The results show that the simulation using Morrison Double-Moment microphysics provides the most and Purdue Lin the least accurate information on cloud cover and surface meteorological variables for the selected high ozone episode. Those two configurations were used for WRF-Chem runs, which showed significantly higher O 3 concentrations and better model-measurements agreement of the latter.

The role of precursor emissions on ground level ozone concentration during summer season in Poland

“…This synoptic situation is common also to other severe ozone episodes in this region, e.g. July 2006 (Wałaszek et al 2014b) and June 2008 (Wałaszek et al 2016). However, to the authors' knowledge, the severe August 2015 ozone episode has not been studied in this region yet.…”

“…Model errors are predominantly systematic and are most likely a result of chemical mechanisms and meteorological fields, i.e. cloud cover and wind speed, both of which greatly affect ozone formation processes and have usually large uncertainties (Wałaszek et al 2016;Wałaszek et al 2014a). Some overestimations may also result from missed or shifted rainfall events (Kryza et al 2013).…”

Geoinformatics and Atmospheric Science: Introduction

“…The WRF model is a large, computationally efficient platform dedicated for forecasting the dynamics of various elements of the atmosphere. Wałaszek et al (2017) use the WRF model to simulate the cloud cover over Poland in the case study for a specific period when ozone concentration was very high. Numerous microphysics parameterization schemes are used, and the authors arrive at the conclusion that the Morrison Double-Moment microphysics is recommended for the scrutinised episode.…”