RT6 Plenary Prague GA Examples of FMIs work Ari Venäläinen, Kirsti Jylhä Ilmatieteen laitos

RT6 Plenary Prague GA Change in the number of snow cover days (%) from to Ari Venäläinen and Kirsti Jylhä

RT6 Plenary Prague GA Observed number of snow cover days Ari Venäläinen and Kirsti Jylhä

RT6 Plenary Prague GA 12 observing stations Variable length of time series Monthly data about 100 years, daily about 50 years Parameters examined: –monthly, two week, five day, daily and six hour precipitation –the length of dry spells (thresholds 10, 50, 100 and 200 mm) Precipitation extremes in Finland Ari Venäläinen and Kirsti Jylhä

RT6 Plenary Prague GA The variation of return level estimates for dry spell lengths among the studied 12 stations Ari Venäläinen and Kirsti Jylhä

RT6 Plenary Prague GA The variation of return level estimates for monthly, two weeks and daily precipitation among the studied 12 stations. Ari Venäläinen and Kirsti Jylhä

RT6 Plenary Prague GA CONCLUSIONS Large differences in the return levels between the 12 stations used in the study, i.e. the level that represents a 10 year return period at one station may be a 500 year level at another location. These differences may be caused not only by the spatial variation of climate but also by the relatively short measuring periods and the limitations statistical extreme value analyses have. The physics behind the most rare events may be something that we are not able to take into account. The changing climate causes further challenges when calculating the return periods. What is past, present and future climate? Future work; similar kind calculations using climate scenarios. Ari Venäläinen and Kirsti Jylhä