Long-term changes in the heat island of Prague under different synoptic conditions

The long term changes of the Prague urban heat island are analyzed separately for different groups of synoptic (circulation) types during the 1961-1990 period. The synoptic types are taken from Bradka's synoptic catalogue, which is in common use in the Czech Republic; and the grouping of types is based on their cyclonicity and directional characteristics. The increase in the heat island intensity is steeper under anticyclonic than cyclonic conditions in all seasons except for spring. The increase in the intensity differs between dominant airflow directions. With only a single exception, the heat island intensification is much larger under the synoptic types with the north to northeast and south to southwest flow than under the other flow directions.