An Investigation on Teleconnection between SOI and NAO Signals and Droughts in Zayanderoud Watershed

The long-term monitoring and forecasting of climatological parameters in each zone can be a suitable technique to deal with the consequence of climatic fluctuations such as drought، flood and etc. The purpose of this study was to identify the Zayanderoud watershed drought and the effect of Southern Oscillation Index (SOI) and the North Atlantic Oscillation (NAO) on climate conditions and climatical parameters such as precipitation. To do this، the long-term time series (1970-2009) of synoptic and climatology stations and the data of NAO and SOI were provided from the site of NOAA. To determine the extent and impact of the NAO and SOI on drought، the correlation between the standard precipitation index at the end of May for 3-، 5- and 8-month time scales and SOI and NAO indices were estimated. Also، the correlation coefficients between seasonally and monthly precipitation in this watershed and the associated indices were calculated. The results showed that the precipitation of Meime، Najaf abad، Freydan، Freydoonshahr، Daran، Chadegan، Koohrang has statistically a significant negative correlation with SOI. However، Esfahan، Freydan and Freydoonshahr have statistically a significant negative correlation with NAO. Shahreza، Abade and Varzane that are located in the dry zone showed no statistically significant correlation with any signals and SOI and NAO indices. The mentioned indices in both synchronized and unsynchronized states showed to have a statistically significant correlation with seasonally and monthly precipitation in different parts of this watershed.