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[MIS01-05] Heavy precipitation over Europe caused by cyclones in recent decades.
Keywords:heavy precipitation, cyclone depth, Atlantic-European sector, reanalysis
The latest studies indicate that global warming is accompanied by an increase in climate extremeness. The precipitation intensification and arid conditions are growing at the same time in most regions of the Earth. These changes are also typical for the European region: there is a trend towards precipitation increase in the northern part of Europe, and a decrease in the south with a simultaneous increase in the number and duration of droughts. However, these trends have spread to the Central and Eastern Europe in recent years.
The heavy precipitation in Europe is associated with extratropical cyclones and convective processes in the atmosphere. Our study presents an evaluation of cyclones originated in the European-Atlantic sector and brining heavy precipitation to Europe during the period of 1979-2019. Cyclones were identified according to the ERA5 reanalysis data. The maximum precipitation totals associated with different types of cyclones have been determined.
Our previous studies showed that precipitation over Europe is provided by 20-25 North Atlantic cyclones and by 5-10 Mediterranean cyclones per season. The daily cyclonic precipitation is about 2-7 mm/day in 50% of cases. The daily precipitation totals caused by the Mediterranean cyclones in spring-summer are the highest among all cyclone types and reach 6-7 mm, in 1/3 cases precipitation totals reach 10-11 mm per day.
In the following step, we evaluated cyclones which bring heavy precipitation (more than 20 mm at least in one point of any cyclone track). The number of these cyclones do not exceed 12% of all cyclones originated and passed the Atlantic-European sector.
The Mediterranean cyclones provide absolute maximum of precipitation totals up to 59 mm, the same totals are detected for the powerful North Atlantic cyclones which originated near eastern coast of North America, passed through the Atlantic Ocean and turned the east-south on the continent. The next by precipitation amount are the North Atlantic cyclones, which regenerated on the fronts of main cyclones while they have been passing the continent. Their precipitation maximum totals are about 40-49 mm. In 2/3 cases the maximal precipitation totals from all types of the cyclones are varied within 12-15 mm, the averaged maximal totals are 9-11 mm.
It was noted that heavy precipitation cases are associated with slow cyclones with speed about 30-50 km/h while average cyclone speed varies within 45-55 km/h. Maximum wind speed in the cyclones associated with heavy precipitation is about 9-13 m/s, with maximal gusts up to 14-19 m/s.
The cyclone depth (difference between last closed isobar and cyclonic center) varies within 6-10 hPa in heavy precipitation cyclones. The cyclone depth may indicate the potential hazard of cyclones. The cyclones that brought heavy precipitation are in most cases characterized by a long lifetime at least 5 days. The cyclone depth changes depend on the duration of the cyclone, and usually does not exceed 5 hPa. The depth of cyclones with heavy precipitation is characterized by high rates on the second or third day and reaches 15-20 hPa. A noticeable increase in the cyclone depth, as a rule, can be found during the first day of cyclone appearance.
The heavy precipitation in Europe is associated with extratropical cyclones and convective processes in the atmosphere. Our study presents an evaluation of cyclones originated in the European-Atlantic sector and brining heavy precipitation to Europe during the period of 1979-2019. Cyclones were identified according to the ERA5 reanalysis data. The maximum precipitation totals associated with different types of cyclones have been determined.
Our previous studies showed that precipitation over Europe is provided by 20-25 North Atlantic cyclones and by 5-10 Mediterranean cyclones per season. The daily cyclonic precipitation is about 2-7 mm/day in 50% of cases. The daily precipitation totals caused by the Mediterranean cyclones in spring-summer are the highest among all cyclone types and reach 6-7 mm, in 1/3 cases precipitation totals reach 10-11 mm per day.
In the following step, we evaluated cyclones which bring heavy precipitation (more than 20 mm at least in one point of any cyclone track). The number of these cyclones do not exceed 12% of all cyclones originated and passed the Atlantic-European sector.
The Mediterranean cyclones provide absolute maximum of precipitation totals up to 59 mm, the same totals are detected for the powerful North Atlantic cyclones which originated near eastern coast of North America, passed through the Atlantic Ocean and turned the east-south on the continent. The next by precipitation amount are the North Atlantic cyclones, which regenerated on the fronts of main cyclones while they have been passing the continent. Their precipitation maximum totals are about 40-49 mm. In 2/3 cases the maximal precipitation totals from all types of the cyclones are varied within 12-15 mm, the averaged maximal totals are 9-11 mm.
It was noted that heavy precipitation cases are associated with slow cyclones with speed about 30-50 km/h while average cyclone speed varies within 45-55 km/h. Maximum wind speed in the cyclones associated with heavy precipitation is about 9-13 m/s, with maximal gusts up to 14-19 m/s.
The cyclone depth (difference between last closed isobar and cyclonic center) varies within 6-10 hPa in heavy precipitation cyclones. The cyclone depth may indicate the potential hazard of cyclones. The cyclones that brought heavy precipitation are in most cases characterized by a long lifetime at least 5 days. The cyclone depth changes depend on the duration of the cyclone, and usually does not exceed 5 hPa. The depth of cyclones with heavy precipitation is characterized by high rates on the second or third day and reaches 15-20 hPa. A noticeable increase in the cyclone depth, as a rule, can be found during the first day of cyclone appearance.