Growing season precipitation in Finland under recent and projected climate

Abstract

Abstract. The past and projected future precipitation sum in May-September for two areas in Finland, one located in the south-west (SW) and the other in the north-east (NE), is studied using 13 regional climate simulations and three observational datasets. The conditions in the present-day climate for agricultural crop production are far more favourable in the south-western part of the country than the more continental north-eastern Finland. Based on a new high-resolution observational precipitation dataset for Finland (FMI grid), with a resolution of 10×10 km, the only statistically significant past long-term precipitation tendencies in the two study regions are positive. Differences between FMI grid and two other observational datasets during 1961-2000 are rather large in the NE, whereas in the SW the datasets agree better. Observational uncertainties stem from the interpolation and sampling errors. The projected increases in precipitation in the early stage of the growing season would be most favourable for agricultural productivity, but the projected increases in August and September might be harmful. Model projections for the future indicate a statistically significant increase in precipitation for most of the growing season by 2100, but the distribution of precipitation within the growing season is not necessarily the most optimal.

Trends in the average temperature in Finland, 1847–2013

“…At the 10 km resolution, a total of 3,829 grid boxes were needed to cover the whole of Finland. Besides, according to Tietäväinen et al (2010), this spatial model has previously been applied in climatological research projects conducted by Venäläinen and Heikinheimo (1997), Vajda and Venäläinen (2003), Venäläinen et al (2005), Vajda (2007), and Ylhäisi et al (2010).…”

Long-term temporal changes in the occurrence of a high forest fire danger in Finland

“…At the same time, anthropogenic climate warming has affected Finland's climate by increasing mean temperatures . As for precipitation amounts, temporal changes are not easy to detect and they are mostly not significant (Ylhäisi et al, 2010). However, despite the different changes in summertime mean temperature and precipitation sum in the past, the summertime climate type itself in Finland has not changed.…”

“…Due to the large year-to-year variation, there can hardly be found any clear trends in the summertime precipitation in the past climate, but for the future climate, models predict an increase in precipitation during summer months (e.g. Ylhäisi et al, 2010). Thus, projections of the future climate show indications both for increasing fire danger due to increasing temperatures and for decreasing fire danger due to increasing precipitation.…”

“…In this study, long, gridded, climate data sets of monthly mean temperature and precipitation sums (Ylhäisi et al, 2010) in Finland starting from the early 20th century are combined with the time series of the Finnish forest fire index starting from the 1960s. Based on the regional correlations between the fire danger data and the climate data, a fire danger day (FDD) model will be developed.…”

“…Climate data consisted of gridded monthly mean temperatures and monthly precipitation sums (Ylhäisi et al, 2010). The gridded climate data have been produced by interpolating station values of monthly mean temperature and precipitation sums from Finnish weather stations, and from selected stations in Sweden, Norway and Russia near the Finnish border to a 10 km grid using a spatial interpolation method called kriging (e.g.…”