A new long-term gridded precipitation data-set for the alps and its application for Map and Alpclim

One of the objectives of EU-project ALPCLIM is the generation of a gridded data-set of monthly instrumental precipitation data. The area of investigation covers the Alps and wide regions of the surroundings from 4° to 18°E and 43° to 49° N. Grid distance is 1 deg longitude and 1 deg latitude. The project is not finished yet, more than 140 single series have been collected by now and are in the state of homogeneity testing and adjusting. The average linear distance of the stations is 75 km. Furthermore first results can be shown, dealing with the main purpose of the generation of the instrumental data-set within ALPCLIM—to use the instrumental data (both temperature and precipitation) to create a longer temperature proxi-data-set based on stable isotope ice core data from high elevation sites in the Monte Rosa and Mont Blanc region. The ice core temperature proxis are supposed to be at least 500 years long. The precipitation series will be used to analyse the problem that ice-cores in principle carry information only for precipitation days, not for all days. Analyses on daily temperature and precipitation data of 50 years series have shown already a way to construct “precipitation-mass weighted mean temperatures” for the longer series based on monthly values. The degree of correlation of those “precipitation-mass-weighted” temperatures with real temperatures will decide on the possibility to use stable isotope proxis from high level sites as temperature information. In addition to the described use within ALPCLIM, also projects like MAP may profit from the outcome of the ALPCLIM precipitation data-set. It will provide the MAP community with carefully homogenised monthly precipitation series to see the situation of MAP-results in a long-term context.