Trends in Turkey Climate Extreme Indices from 1971 to 2004

Extreme climate events usually have strong impacts on society and a small change in the mean condition can cause a large change in the likelihood of an extreme. A joint WMO CCl/CLIVAR Expert Team (ET) on Climate Change Detection, Monitoring and Indices has defined 27 core climate indices mainly focusing on extreme events using freely available software, RClimDex, developed and maintained on behalf of the ET by the Climate Research Branch of Environment Canada.. Indices have the advantage that they can be freely exchanged within the international scientific community. The complete list of the 27 indices, RClimDex software and users guide are available from http://cccma.seos.uvic.ca/ETCCDMI. In this study, we have run RClimDex software to calculate climate extreme indices for about 100 stations in Turkey for the period from 1971 to 2004. The results show that numbers of summer days and tropical nights have been increasing all over Turkey while ice days and frost days decreasing. Summer days have increased about 6 days per decade. Most of the trends are statistically significant at the 5% level. Growing season length has increased over Turkey except for coastal regions. This will be have a positive effect on summer agricultural products but some negative affects will be experienced by orchards for example which rely on cold conditions. Maximum of maximum, minimum of maximum, maximum of minimum and minimum of minimum temperatures have increased at most stations. Warm days and warm nights have been increasing all over Turkey while cool days and cool nights have been decreasing. Warm spells have increased while cold spells have decreased. Diurnal temperature range has increased in most inland stations while it has decreased along coastal areas. Trends in simple daily intensity index have been increasing in most of the stations even mean annual total precipitation declined in 30 stations located in the Aegean and inland Anatolia. The number of heavy precipitations days have been increasing especially in the Black Sea and Mediterranean regions and usually cause extreme flood events. The maximum one-day and 5 days precipitation have also increased except eastern Marmara and south Anatolia region. Consecutive dry days have