Synoptic conditions of advection of arctic and tropical air masses over the Lublin region

Abstract

The aim of the study is to characterize the frequency and determinants of the synoptic conditions of advection of arctic and tropical air masses over the Lublin region. Their occurrence in the regional scale in the years 1951–2010 was based on lower synoptic maps for 12 UTC, which derived from PIHM/IMGW-PIB. In turn, the calendar of circulation types for the Lublin region was used to assess the synoptic conditions of the analyzed air masses. The annual frequency of arctic air masses reached 13.4%. The highest frequency of these air masses occurred in spring, with the maximum in April (20.4%), and the lowest in summer (July and August, < 5%). Days with tropical air were recorded less frequently (4.1% of all days in the year). It is most often found in the summer (with a maximum of 9.2% in July) and the lowest in winter (< 1%). In the years 1951–2010, there were signifi cant changes in the frequency of advection of arctic and tropical air masses (average increase by 8 and 3 days per 10 years, respectively). The occurrence of arctic masses signifi cantly increased in winter, autumn and spring, and tropical in the summer. In all seasons, the arctic air was most likely to be recorded during the northern and northeastern circulation types, while the lowest in the southern and southwestern types. In the case of tropical air, it is most likely to occur during air fl ow from directions E-SE-S-SW. Regardless of the time of the year, arctic and tropic air masses are characterized by signifi cant anomalies in air temperature at 850 hPa and 850–1000 hPa thickness.