High frequency variability in recent climate and the north atlantic oscillation

High-frequency temperature variability was investigated in the temperature time series measured at Prague-Sporilov (Czech Republic) between 1994-2001. The calculations were performed for time series of surface air temperature averaged for 6-hour intervals. Variability was detected by the method of absolute difference of temperature anomalies between two adjacent discrete time periods. The results indicated a frequency dependence of variability. For 24-hour intervals the variability exhibits an irregular character and decreases with time in the eight-year observation period. Variability time series calculated for the 6-hour intervals did not reveal any significant trend, however, apparent quasi-seasonal oscillations exist. A significant correlation between the North Atlantic Oscillation (NAO) activity and temperature variability can be observed. Higher NAO-index values at all frequencies tend to be associated with higher variability.