Creating Bioclimatic Maps Using Spatial Interpolation Techniques in Northern Turkey

Abstract

This study used Geographical Information System (GIS) and spatial interpolation techniques to calculate the spatial distribution of various bioclimatic indices for Northern Turkey. The results varied among the indices. Ordinary Kriging (OK) was the most appropriate method for producing bioclimatic maps of summer drought stress (SDS), winter cold stress (WCS), Rivas-Martinez om-brothermic (O-i) and continentality (C-i) in the study area. On the other hand, Simple Kriging (SK) was the best fitted interpolation method for De Martonne Aridity Index (I-DM). Thin Plate Spline (TPS) had the highest root mean square error (RMSE), whereas the lowest RMSE values were derived from Inverse Distance Weighting (IDW) and Spline with P=2. In general, the lowest RMSE values were obtained with N=8 and N=12. Spatial maps produced by the most appropriate methods showed different climatic conditions. Whereas SDS values were similar along the coast and then increased in line with movement towards the interior, WCS values were lower along the coastline, and then increased with movement inland.In terms of I-DM, the study area was classified into 5 different regions, from semi-dry to very humid. Whereas the results for SDS, WCS and I-DM were in harmony with one another,O-i showed the entire region to be hyperhumid, which is incompatible with the results of the other indexes as well as with the observable conditionsin the region. C-i indicated the region to be predominantly defined as oceanic.