A statistical survey on linking between thunderstorm frequency and teleconnection patterns in Iran

Abstract

This study aims to find the effect of teleconnection patterns on daily thunderstorm frequency (DTF) in Iran. The data applied for this attempt were the DTF occurrence of 25 synoptic weather stations and 12 teleconnections in a 51-year period during 1960–2010. The main methods applied were Kriging geostatistical method, Pearson correlation, multiple regression, and analysis of variance. Analyzing the monthly correlation of DTF with teleconnection patterns, it was revealed that this relation was significant and meaningful in May, June, and October in the South, West, and East regions with regard to the sea surface temperature (SST) of the Pacific Ocean, multivariate ENSO index (MEI), and Southern Oscillation Index (SOI), and the correlation was significant in the northern areas with the Arctic Oscillation (AO) index. The seasonal analysis also pointed to the significant and meaningful correlation between MEI and SST indices and southern and western regions of the country in spring and autumn. The annual DTF was similar to seasonal intervals in that they showed meaningful correlation of this event with MEI and SST, in all regions of the studied area. Multiple regression and analysis of variance showed that in May, June, and October, as well as spring, autumn, and the annual interval, the highest variation in DTF in stations located in the south and east of the country can be explained with the fluctuations of teleconnection patterns of the El Nino Southern Oscillation (ENSO), AO, and North Atlantic Oscillation (NAO). Generally, the effect of teleconnection patterns which are efficient in the occurrence of DTF can be better studied through the SST of the Pacific Ocean, MEI, SOI, and AO.