Jacek Walczewski

Relations between occurrence of circulation type (Lityński's classification) in Cracow and occurrence of 24hour inversions in 1994-2005

Acoustic soundings of boundary layer have been carried out in Cracow since 20 years, using sodar (up to 1000 m) due to investigate conditions of air pollutants from low domestic source. Data sets allowed to estimate a frequency of occurrence of inversions (i.e. increase of temperature with height) in planetary boundary layer. Hence, a correlations between inversion occurrence and synoptic situation has been studied. The term “synoptic situation" here means occurrence of miscellaneous types of atmospheric circulation (according to 15 types of Litynski's classification). Period of ten years has been under investigation (1994-2005, excluding 1995 and 2002 due to lack of data). This period has been divided into two sub-periods 1994-2000 (excluding 1995) and 2001-2005 (excluding 2002), climatologically different (maximum number of days with inversions in given type of circulation in first period was 50%, in second - 37%). Conditional probability of day with long (24hours) inversions was also studied. Circulation characteristic of 3650 days was also carried out using sodar data as well. Circulation types SC+SWC (13) and WC+NWC (14) were found in groups with major inversion percentage in both periods, while 0A (5), EC+SEC (12), 0C (15) and 00 (10) - with minor percentage. These data may be used for forecasting of atmospheric pollutants.