Joanna Struzewska

First application of MC2-AQ to multiscale air quality modelling over Europe

Abstract A three-dimensional air quality model (MC2-AQ) developed for studying oxidant chemistry on regional to urban scales over North America was adapted and implemented for European conditions. The modelling system is based on the Canadian Mesoscale Compressible Community (MC2) Model, a non-hydrostatic meteorological model, to which modules permitting on-line calculations of chemical transformations, anthropogenic and biogenic emissions, and deposition were added. The transport of chemical species is done on the same grid and with the same advection, convection, and diffusion schemes as are used for the meteorological fields. The developed model is highly flexible and was adapted to different scales by allowing for self-nesting. In this paper we present model results for a high-ozone episode, June 18–26, 2000, over Europe. The modelling system was able to reproduce general characteristics (growth, extent, and dissipation) of the pollution episode. Accumulation of ozone precursors during weak wind and high-temperature synoptic conditions was essential for episode formation. Subsequent episode development and advancement across Europe was driven by frontal systems. A stationary front associated with a low-pressure system over Ukraine prevented the further eastward transport of the polluted air mass. The episode was terminated after the passage of a cold front advecting relatively clean Atlantic air mass.

Interannual variability of tropospheric NO2 column over central Europe — observations from SCIAMACHY and GEM-AQ model simulations

Spatial and temporal variability of NO2 tropospheric column over Europe was analyzed for a 3 year period (2008–2010) based on monthly average observations from SCIAMACHY and the GEM-AQ model results. The GEM-AQ model was run in a global variable configuration with a resolution of ∼15 km over Central Europe. Spatial averaged time series were calculated for two selected regions in Western and Central Europe in order to assess the seasonal and interannual variability of the tropospheric NO2. The spatial pattern is similar near large emission sources for consecutive years. However, in remote regions there are differences due to interannual variability of meteorological conditions. Highest tropospheric NO2 column values (over 150 × 1015 molecules/cm2) were persistent over the Benelux and over most of the European agglomerations. The general agreement between modelled and observed NO2 column is good. In the remote areas, the modelled NO2 column shows weaker gradients than the observed field.

The impact of urban morphology and land cover on the sensible heat flux retrieved by simultaneous satellite and in-situ observations

Retrieval of sensible heat flux requires the input of, among others, temperature gradient and wind speed. The lower level of temperature measurement is commonly replaced by remotely-sensed radiative surface temperature. Studies that utilize simultaneous satellite and in-situ retrievals of sensible heat flux are scarce. In this paper, we present preliminary results of the analyses of the impact of urban morphology and land cover on the sensible heat flux. It was calculated by two approaches, the first was based on satellite observations of radiative surface temperature and the second utilized in-situ measurements of road kinetic temperature. Except for the surface temperature, for both approaches we used the same input parameters. Road kinetic temperature and wind speed were measured by automatic road weather network. Nine stations were located across the city of Warsaw outside the city centre in low-rise urban structure. A time series of MODIS thermal data for the period 2005-2014 was utilized.

A 15-Year Analysis of Surface Ozone Pollution in the Context of Hot Spells Episodes over Poland

Analysis of summertime temperature characteristics and ozone exposure indexes were carried out for eight locations in Poland for a 15-year period (1997–2011). The number of days with the maximum temperature exceeding 25°C and 30°C was calculated for each year. The analysis covered the 8-hour running average and daily maximum of near surface ozone concentrations. Also, the accumulated exposure when ozone concentrations were above 120 μg/m3 (AOT60) was calculated as a diagnostic indicator of adverse health effects for each year. Although high ozone concentrations are associated with hot temperatures, the exposure to values higher than 120 μg /m3 is correlated with the length of the hot weather period rather than with the occurrence of days with extremely high temperatures. In most cases the elevated ozone concentrations occurred during days when the maximum temperature was higher than 24°C. Episodes of very high ozone concentrations, exceeding 180 μg /m3, were not associated with heat wave periods at analysed locations.

Multiscale Atmospheric Chemistry Modelling with GEMAQ

Tropospheric chemistry and air quality processes were implemented on-line in the Global Environmental Multiscale model. The integrated model, GEM-AQ, was developed as a platform to investigate chemical weather at scales from global to urban. The current chemical mechanism is comprised of 50 gas-phase species, 116 chemical and 19 photolysis reactions, and is complemented by a sectional aerosol module with 5 aerosols types. All tracers are advected using the semi-Lagrangian scheme native to GEM.