Geographical Research

The main purpose of this article is، showing similar fluctuation of temperature series and their consistency with what happened in the global level. In addition، it determines new estimates of regional seasonal and annual temperature trends over Iran، after the detection of artificial and natural non homogenous points of 33 synoptic stations for the period of 1960 2010. The 22 stations with shorter records are used only to confirm variability during overlapping periods as evidence. Due to similarity of the results of homogeneity tests and also to prevent of complexity، assessing of data homogeneity have been surveyed only by using the results of Standard Normal Homogeneity test (SNHT)، expert judgment and Metadata. The results showed، the country may be segmented to 10 such regions in terms of trends and variability of temperature. In addition، it was shown، the country with having different climatic type and with facing similar natural fluctuation، have experienced similar variability and fluctuation of temperatures in all regions at nearly equal rates of 0.4-0.5 and 0.2-0.3 (°C /decade) for annual minimum and maximum temperature، respectively in Iran. Non homogeneities in the temperature series relate mostly to relocation and changes of environmental conditions at individual stations. In the case of ignoring these non homogeneities، it is appeared errors in the statistical characteristics of temperature، Furthermore، it will be followed uncertainties in spatially averaged trends. The finding in earlier work of a few individual stations with negative trends is found to be due to artificial effects like relocation.