Ulrik Smith Korsholm

On-line Integrated Meteorological and Chemical Transport Modelling: Advantages and Prospectives

The strategy for developing new-generation integrated Meso-Meteorological (MetM) and Atmospheric Chemical Transport Model (CTM) systems is discussed and an overview of the European COST728 (http://www.cost728.org) integrated systems is given. Advantages and disadvantages of on-line integration versus the more common off-line coupling of MetMs and CTMs are mentioned using DMI-ENVIRO-HIRLAM (HIgh Resolution Limited Area Model) as a specific example. Current progress in the DMI-ENVIRO-HIRLAM system development and its urban on-line coupled modelling applications are considered. Several sensitivity tests of off-line versus on-line coupling in DMI-ENVIRO-HIRLAM as well as verification versus the ETEX experiment are considered, and results are discussed.

Air Quality in the Nordic Countries and Climate Changes in the Arctic

The report use ozone measurement data retrieved in the Arctic with balloon borne ozone sondes for the last 20-30 years. Four stations with the best data series have been selected. Using a Monte Car ...

Time series analysis of Arctic tropospheric ozone as short-lived climate force

Ozone soundings from 9 Nordic stations with rather different data coverage have been homogenized followed by an interpolation to standard tropospheric pressure levels. A Bayesian model was applied ...

Overview of DMI ACT-NWP Modelling Systems

The multi-scale multi-module off-line and on-line coupled atmospheric chemistry transport and numerical weather prediction modeling systems developed and employed at the DMI are described. Several physics, chemistry, and aerosol modules which are currently implemented into used models for different applications are outlined. Recent developments and testing of these models are presented on examples, which show promising results.

Status and Evaluation of Enviro-HIRLAM: Differences Between Online and Offline Models

Online coupled model systems in which a meteorological model contains emissions, transport, dispersion, deposition, chemistry and aerosol physics of pollutants have recently received much attention, mainly due to the prospects of including feedbacks between pollutants and meteorological fields and quantifying indirect effects. There are, however, several other important differences between online and offline coupled models and in this context it is important to investigate when online models are useful. This study presents the current status of Enviro-HIRLAM, an online coupled model developed at the Danish Meteorological Institute, and investigates the importance of increased availability of meteorological information to transport and dispersion. Enviro-HIRLAM is shown to perform satisfactory during tests of transport, dispersion and deposition, using data from the first European Tracer Experiment (ETEX-1) and measurements of deposited Cesium-137 made after the Chernobyl accident. Offline and online simulations of the ETEX-1 release are compared and it is shown that the offline coupling interval plays an important role in constraining the influence of meso-scale disturbances on (long range) plume development.