Strong anticyclones and deep cyclones over Svalbard in the years 1971-2015

This paper presents annual and long-term variability in the occurrence of cyclone and anticyclone centres over Svalbard during the period 1971-2015. The study is based on average daily air pressure values at sea level for 12 grid points and on the typology of synoptic situations. Particular emphasis is placed on the occurrence of deep and very deep cyclones (with a pressure of <= 990 hPa and <= 970 hPa, respectively) and strong and very strong anticyclones (with a pressure of >= 1030 hPa and >= 1035 hPa, respectively). On average there were about 17.5 days with a cyclone and 4.9 days with an anticyclone centre over Svalbard annually. The results of the analysis show no clear trend in the number of cyclones moving over the study area, but there was an observable increase in the frequency of anticyclones. There were also no major changes in the annual maximum of occurrence of the pressure systems under study.