The study of two cases of severe flooding over the Eastern Azerbaijan Province from the synoptical and kinematic view and coincident of these events with GFS precipitation forecast (period on 2000-2010)
Subject Areas : Marine Physics
Kh.
Porjavad Asl
1
(Faculty of Marine Science and Technology, Islamic Azad University Tehran North Branch)
F.
Arkian
2
(Faculty of Marine Science and Technology, Islamic Azad University Tehran North Branch)
Keywords: Flood, Blocking, Eastern Azerbaijan, Inverted Thermal Trough, Cut-off Low,
Abstract :
Our statistical study showed that during period 2000-2010, Eastern Azerbaijan Province was threated by numerous severe floods. These occurred during spring with a frequency of 66% and summer with 28% and fall with 4% and winter with only 2% frequency. From damages viewpoint, we selected two of most severe floods of the province to work on. The first one was in Tabriz city, centre of Eastern Azerbaijan Province, on 14th of May 2007. The other one occurred in Mianeh city on 18th of June 2009. For studying the two severe floods, we analyzed synoptic charts at all standard levels for 13-15th of May 2007 and 17-19th of June 2009. We found an inverted thermal trough at the earth’s surface impacting with baroclinic short waves trough that moving fast from west to east over the region. The above features were induced by two blocking patterns. First one was a blocking high, located over north of Siberia, and second one was a Cut-off low, located over north of central Europe. The magnitude of upward mention over 700hpa level troughs, was and magnitude of absolute vorticity over 500hpa, level troughs were in the range of . the main pattern for the second flood, occurred in Mianeh, was also an inverted thermal trough at the earth’s surface, impacting a could cut-off low in middle and upper troposphere, located over Turkey for this case, we found that the magnitude of upward motion in the centre of cut-off low at 700hpa was and magnitude of absolute vorticity in the center of cut-off low at 500hpa was but at the same time absolute vorticity over the province was . The total daily amounts of precipitation forecast from GFS model was in a good harmony with recorded daily precipitation in the stations for the Mianeh flood but for Tabriz’s flood, the result was not appropriate.
