Investigation of Displacement of Minimum Temperatures Temporal and Spatial Cores in West and Northern West of Iran

    Investigation of Displacement of Minimum Temperatures Temporal and Spatial Cores in West and Northern West of Iran    B. Alijani.   Professor of climatology, Tarbiat Moallm University, Tehran, Iran.     P. Mahmoudi. ( * ), PhD student of climatology, University of Sistan and Baluchestan, Zahedan, Iran.   email: paymanasia@yahoo.com     A. Panahi .  M.A. of climatology, Applied Meteorology Research Centre, Sanandaj, Iran.   Received: 26 October 2009 / Accepted: 17 August 2010, 13-16 P     Extended Abstract   1- Introduction   One of the prominent challenges in current century is climate changes. Among weather parameters, temperature changes as the most basic element of the weather in every district have special importance.   The west and the north-west of Iran, where is a mountainous region and full of snow, consider as water sources for great rivers and also underground water supply.   Therefore, every climatic change in these parts particularly in a cold season,     not only causes changes in a hydrology cycle also in a rainfall regime, soil moisture regime, cultivation pattern, increase or decrease of climatic crisis.   So, recognition and enquiry of changes and fluctuations in different climatic parameters according to different intervals can provide a very noticeable outlook for future programs.   As a result, 2 goals which this research has been pursuing are   · To appoint temporal and spatial cores of severe colds in the west and the north-west of Iran.   · Understand a process of replacement of temporal and spatial cores of severe colds in the west and the north-west of Iran.       2- Methodology   For investigation a replacement of temporal and spatial cores of minimum temperatures in the west and the north-west of Iran and for achieving the aims of this study, data related to absolute minimum temperatures in November to May for 30 years (1976-2005) were collected from 11 select stations from Meteorological organization of Iran.   Cold indicator waves were extracted in related to factors such as, set at least four stations in one group that have the lower minimum temperature and also 2 days intervals exist between elected heads and a group in former stations. The number of collected heads was 283.After appointing cold waves wavelength was defined for all of them based on the number of days and timely core. The coldest station that had the lowest temperature in every group was specified according to the maximum stations in one day in every single head and timely core.   For recognizing the spatial displacement of cold cores, have been divided the study into three interval subgroups during 10 years and changes of spatial cores of annual cold were computed in every interval subgroups and by using” SURFER” and kriging method changed them to maps and then movements of spatial cores were interpreted using maps. Also computed timely movements of coldness cores by using regression method.       3- Discussion   Investigation of displacement of spatial cores of annual indicator heads indicated that the principal place for cold cores is” Nozhe Hamedan” station which showed 6 times frequency in the first decade.   In second decade this place changed from Nozhe Hamedan to Ardebil with 6 times frequency and in third decade from Ardebil to Saghez with 5 times frequency.   So, we can see that one movement in coldness cores happened from approximately 35 degree latitudes to higher than 36 degree ones.   For analyzing the timely displacement of cold cores, consider “years” as independent variable and “a day of happening” as a dependent variable.   Consequences from this analysis show that one displacement in temporal cores cause severe cold in the west and the north-west of Iran. In a way that temporal cores of annual indicator show displacement from early February and late January to late December. It should be mention that this displacement in a 5 percent possible level is not definite.     4- Conclusion   The result of this study showed that one displacement in spatial cores of cold indicator heads in a duration of study (1976-2005) is observable in away that this displacement is from 35 degree geographical latitudes to higher than 36 ones.   Also consequences of analysing the process of temporal cores of indicator heads indicate one movement in temporal cores that cause a severe colds in the west and the north-west of Iran in a manner that temporal cores of annual indicator show displacement from early February and late January to early January and even late December.   It should be mention that these displacements in 5 percent possible level are not definite.   Another point that also originates from the research is when displacement of spatial and temporal cores of cold indicator heads in the west and the north-west of Iran happen, the temperature of indicator heads becomes decreases, which means become colder.   Key words : temporal core of cold- spatioal core of cold, West and Northwest Iran, climate change, Cold wave       References   Alijani, A., M. 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