The influence of north atlantic oscillation on local drought occurrences in the iberian peninsula using the vegetation temperature condition index

Due to its climatic characteristics the Iberian Peninsula is frequently afflicted by droughts, though with a high spatiotemporal variability. The North Atlantic Oscillation (NAO) is the major atmospheric circulation pattern influencing rainfall events in Iberia. The study evaluates the impact of the NAO on local drought occurrences in Iberia for spring and summer seasons during the years 2001-2005, 2007 and 2010. The Vegetation Temperature Condition Index (VTCI) is a remote sensing drought index that uses information on vegetation activity and land surface temperature. A point correlation analysis between NAO and biweekly VTCI was applied and maps were produced at a confidence level of at least 90%. A clear correlation pattern was found for summer months showing positive correlation in the NW and negative correlation in the S and SE of the Iberian Peninsula. In spring, April reveals the strongest correlation, whereas the pattern is reverse to June. Spring months play an important role for water availability of plants. This study shows that knowledge about the influence of NAO at a local scale can be useful for developing an outlook system for soil moisture conditions especially for spring months.