Abstract. The impact of climate change on surface ozone over Europe was studied using four offline regional chemistry transport models (CTMs) and one online regional integrated climate-chemistry model (CCM), driven by the same global projection of future climate under the SRES A1B scenario. Anthropogenic emissions of ozone precursors from RCP4.5 for year 2000 were used for simulations of both present and future periods in order to isolate the impact of climate change and to assess the robustness of the results across the different models. The sensitivity of the simulated surface ozone to changes in climate between the periods 2000-2009 and 2040-2049 differs by a factor of two between the models, but the general pattern of change with an increase in southern Europe is similar across different models. Emissions of isoprene differ substantially between different CTMs ranging from 1.6 to 8.0 Tg yr −1 for the current climate, partly due to differences in horizontal resolution of meteorological input data. Also the simulated change in total isoprene emissions varies substantially across models explaining part of the different climate response on surface ozone. Ensemble mean changes in summer mean ozone and mean of daily maximum ozone are close to 1 ppb(v) in parts of the land area in southern Europe. Corresponding changes of 95-percentiles of hourly ozone are close to 2 ppb(v) in the same region. In northern Europe ensemble mean for mean and daily maximum show negative changes while there are no negative changes for the higher percentiles indicating that climate impacts on O 3 could be especially important in connection with extreme summer events.

The impact of climate change on surface ozone over Europe was studied using four offline regional chemistry transport models (CTMs) and one online regional integrated climate-chemistry model (CCM) driven by the same global projection of future climate under the SRES A1B scenario. Anthropogenic emissions of ozone precursors from RCP4.5 for year 2000 were used for simulations of both present and future periods in order to isolate the impact of climate change and to assess the robustness of the result across the different models. The sensitivity of the simulated surface ozone to changes in climate between the periods 2000–2009 and 2040–2049 differs among the models, but the general pattern of change with an increase in southern Europe and decrease in northern Europe is similar across different models. Emissions of isoprene differ substantially between different CTMs ranging from 1.6 to 8.0 Tg yr⁻¹ for the current climate, partly due to differences in horizontal resolution of meteorological input data. Also the simulated change in isoprene emissions varies substantially across models explaining part of the different response. Average model changes in summer mean ozone and mean of daily maximum ozone exceed 1 ppb(v) in parts of the land area in southern Europe. Corresponding changes of 95-percentiles of hourly ozone exceed 2 ppb(v) in the same region. Over land areas in northern Europe ensemble mean changes in all these measures are mostly negative

The aim of this paper is to describe the use of a general methodologytailored to the evaluation of micro-scale meteorological models appliedto flow and dispersion simulations in urban areas. This methodology,developed within COST 732, has been tested through a large modellingexercise involving many groups across Europe. The major test caseused is the Mock Urban Setting Test (MUST) experiment representingan idealised urban area. It is emphasised that a full model evaluationis problem-dependent and requires several activities including astatistical validation that requires a careful choice of the metricsfor the comparison with measurements

The Greenland ice sheet (GrIS) covers a complex network of canyons thought to be preglacial and fluvial in origin, implying that these features have influenced the ice sheet since its inception. The largest of these canyons terminates in northwest Greenland at the outlet of the Petermann Glacier. Yet, the genesis of this canyon, and similar features in northern Greenland, remains unknown. Here, we present numerical model simulations of early GrIS history and show that interactions among climate, the growing ice sheet, and preexisting topography may have contributed to the excavation of the canyon via repeated catastrophic outburst floods. Our results have implications for interpreting sedimentary and geomorphic features beneath the GrIS and around its marine margins, and they document a novel mechanism for landscape erosion in Greenland.