An explanation of persistence in monthly mean temperatures in the Netherlands

Abstract

Persistence of the anomalies in the monthly mean air temperature has been investigated thoroughly for 15 stations in the Netherlands. All stations used have records of at least 50 years. The persistence is expressed in the correlation coefficient of the air temperature of adjacent months. At all stations the correlation coefficient is high at the end of summer and winter and smaller in the other months. With so many stations in a small area we were also able to resolve large spatial variations. In general, persistence is large close to and over the sea and decreases over land with increasing distance from the coast. We conclude that besides a background persistence caused by the large-scale atmospheric circulation, there is a strong persistence directly controlled by the North Sea, which has a large gradient in the coastal area. The variations of persistence throughout the year can be qualitatively explained by considering (1) the persistence of the sea surface temperature anomaly, (2) the stability of the atmospheric boundary layer over the sea and (3) the stability of the atmospheric boundary layer over land. Finally, we discuss the skill of forecasting schemes based on simple persistence.