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MISU research seminar | Martin Hagman

Model representation of low clouds in the Arctic boundary layer

by Martin Hagman
PhD student at the Department of Meteorology (MISU)

Time: 6 December 2018, 14h45–15h15
Venue: Rossbysalen C609, Arrhenius Laboratory, 6th floor

Abstract
The Swedish Armed Forces have been using one set of the WRF model during a couple of years to issue forecasts for Scandinavia and parts of Finland. During this time, it has been noticed that the model has severe problems to represent and to depict the development of low clouds. The problem is pronounced during wintertime over the northern parts of the area when the boundary layer is stably stratified, especially over snow-covered ground. So far, no study of the origin of the excess cloudiness has been made. Generally, this problem doesn’t seem to appear to the same extent in the IFS, Arome or in the HIRLAM-models.

To find a solution for this problem I have set up the WRF-system over Scandinavia in the same way that it is done in the Swedish Armed Forces. To study the behavior of the model I have made reruns and looked at data for the site of Sodankylä in northern Finland. The period is chosen to be January and February 2018.

Sodankylä is a good place to evaluate, because there are a lot of observational data here to compare with. What we have found out so far is that the vertical interpolation from the ECMWF analysis seems to work out fine. We have also found that the initialisation of the model is one part of the problem. A more in-depth analysis have been conducted by setting up a single column(SCM) version of WRF for Sodankylä.

In this seminar I will show you the magnitude of this low cloud-problem and also present some results from both the full scale model and the SCM.

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