Grid-mode-1 series are anomaly series interpolated to a regular grid of 1° latitude and 1° longitude ranging from 4° to 19°E and from 43° to 49°N.
Like CRSM-series, also “grid-1” series intend to reduce still remaining undetected inhomogeneities/outliers through the process of averaging. They overcome any remaining inhomogeneities of the network in terms of spatial distribution of the sites and they allow for easier and more systematic use in many kinds of analyses. The method applied was a modified Gaussian weighted inverse distance interpolation. The filter width of the weighting function was set with respect to spatial decorrelation of the respective climate element (Auer et al, 2007 , Fig.10 , Fig.11). Some few existing steep climate gradients in the region like the alpine main chain for all elements, coastal versus inland for temperature and a few others were initially defined as barriers for any information transport. Also the search radius was set according to the specific spatial decorrelation. This is a measure to avoid transfer of information to a gridpoint over unrealistic long-distances especially in earlier times when network density was lower.
For temperature, two such grid-1 datasets were produced. The version “high-elevation” is only present for grid-points in the direct alpine realm and was calculated from a selection of high- elevation or summit series. The version “low-elevation” comprises all grid points in the GAR.
For precipitation the series from the wind exposed summit sites had been excluded from the stmod-dataset already (Auer et al., 2005 ), due to the well known uncertainties of precipitation measurements at high elevated Alpine sites. Consequently, no high elevation grid-1 version was produced.
For air pressure only sites up to a maximum altitude of 650m asl were used for gridpoint-interpolation. These low elevation fields can be expected to mainly carry information usable for questions of circulation. Higher elevated sites were excluded due to their systematic bias originating from the temperature and humidity of the atmospheric layers beneath. However, respective studies targeting directly on such effects, have to remain on the respective low- and high elevation pairs of stmod series (e.g. Böhm et al 1998 ).
Currently the following grids are available (compressed as zip, size approx. 500kB)
A fourth grid-1 mode is envisaged for the future: it will be anomaly series of the climate parameter sunshine duration