Statistical downscaling of climate scenarios over Scandinavia

Abstract

Studies from recent years involving development and application of statistical downscaling models for Scandinavia (mainly Norway and Sweden) are reviewed. In most of the studies linear techniques were applied. Local temperature and/or precipitation were predictands in a majority of the studies. Large-scale temperature fields, either from 2 m or 850 hPa, were found to be the best predictors for local temperature, while a combination of atmospheric circulation indices and tropospheric humidity information were the best predictors for local precipitation. Statistically downscaled temperature scenarios for Scandinavia differ depending on climate model, emission scenario and downscaling strategy. There are nevertheless several common features in the temperature scenarios. The warming rates during the 21st century are projected to increase with distance from the coast and with latitude. In most of Scandinavia higher warming rates are projected in winter than in summer. For precipitation, the spread between different scenarios is larger than for temperature. A substantial part of the projected precipitation change is connected to projected changes in atmospheric circulation, which differ considerably from one model integration to another. A tendency for increased large-scale humidity over Scandinavia still implies that projections for the 21st century typically indicate increased annual precipitation. This tendency is most significant during winter. In northern Scandinavia the projections tend to show increased precipitation also during summer, but several scenarios show reduced summer precipitation in parts of southern Scandinavia. Comparisons with results from global and regional climate models indicate that both regional modeling and statistical downscaling add value to the results from the global models.

Recent forest limit changes in south-east Norway: Effects of climate change or regrowth after abandoned utilisation?

“…Future projections of precipitation, snow and wind are more uncertain than the predictions of a warmer climate (Benestad 2002;Hanssen-Bauer et al 2005;Raper & Giorgi 2005;Solomon et al 2007). None of the tested snow variables in this study explained any forest height growth changes for Norway spruce.…”

“…Future temperatures are expected to rise more in the winter season than in the summer season (Hanssen-Bauer et al 2005). The winter season, however, is not a period of plant growth, and the tree species in the study area 'have passed the selection filter' (Kö rner & Paulsen 2004, 714) and are adapted to cold and variable winters (e.g.…”

Statistical downscaling of daily mean temperature, pan evaporation and precipitation for climate change scenarios in Haihe River, China

“…For many regional and local applications, users of climate model results have long been dissatisfied with the inadequate spatial scale of climate scenarios produced from coarse resolution GCMs outputs (Cubasch et al 1996;Risbey and Stone 1996;Eric and Salathe 2003). In the past couple of decades, different downscaling methods have been proposed in order to deal with the problem of spatial scale mismatch, and these methods have been widely used in their cradles, such as Europe and USA (Hanssen-Bauer et al 2005;Fowler and Wilby 2007;Hellstrom et al 2001;Wilks 1989;Murphy 2000;Hayhoe et al 2004;Vrac et al 2007;Coulibaly 2004;Wetterhall et al 2005Wetterhall et al , 2006Wetterhall et al , 2007.…”

An evaluation of statistical models for downscaling precipitation and their ability to capture long‐term trends

“…It is well known that much of the precipitation (orographic rain) along the west coast of Norway can be related to westerly winds (Henry, 1922), and hence SLP patterns (Nordli et al, 2005;Hanssen-Bauer et al, 2005), but SLP PMs may not be as skillful in other parts of the world, such as in the interior of continents. Thus, it is not given that the SLP PM yields the highest 'cor'-or r-scores for other regions.…”