Analyzing the spatial variability of precipitation extremes along longitude and latitude, northwest Iran


  • Mohammad Arab Amiri Department of Geographic Information System, Faculty of Geodesy and Geomatics Engineering, K.N.Toosi University of Technology, Tehran, Iran
  • Mohammad Saadi Mesgari Department of Geographic Information System, Faculty of Geodesy and Geomatics Engineering and Center of Excellence in Geospatial Information Technology (CEGIT), K.N.Toosi University of Technology, Tehran, Iran


Geo-referenced time series, GIS, Simple precipitation intensity index, Weather extremes, Surface approximation


Precipitation extremes can have significant impacts on the environment and human activities. The simple precipitation intensity index is one of the most commonly used extreme indices, which can represent the extreme precipitation characteristics in the desired time period. The main objective of this research is to realize a spatial analysis of precipitation extremes in
northwest of Iran to investigate spatial trends along longitude and latitude in decadal time scale. Geo-referenced time series from 22 synoptic stations between the years 1991 and 2010 were used. Polynomial fit functions were used for analyzing the spatial variability of extreme precipitation. Besides, the significance of each individual trend surface model order was tested
against the F ratio in order to select the most proper polynomial order for each period. The analyses of extreme precipitation identified significant spatial trends to the intercardinal directions, especially to the southwest. The results of the analysis of the magnitude of changes also showed increasing trends over the whole period.


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