Production of Daily Cyclonicity Indices and its effect on temperature and precipitation over Khorasan region in 1948-2010 Period

Cyclonicity Index in upper level (surface level) may indicate the effects of trough (cyclone) or ridge (anticyclone) pattern over an area. The goal is to create Daily Cyclonicity Indices (DCI) in 500 and 700hPa level over Khorasan province focusing on Mashhad in 1948-2010 period as well as to estimate the frequencies (days/year) of upper circulation types and effect of DCI on temperature and precipitation in region. Daily means of geopotential maps in 500 (and 700) hPa level (23011 numbers) were extracted from NCEP/NCAR Reanalysis Published by NOAA. In upper level five types of atmospheric circulation are diagnosed as follows: area influenced by trough line (TL), trough edge (TE), geopotential col or unclassified pattern (COL), ridge edge (RE) and ridge line (RL). Time series of DCI were then resulted. The frequency averages annually in the total period for the circulation types, TL, TE, COL, RE and RL, are respectively 67, 15, 111, 105 and 66 (days/year). This research showed that the Khorasan area are under: low geopotential height (trough pattern: TL+TE) in 23% of days/year, geopotential col (or unclassified) in 13% of days/year, high geopotential height (ridge pattern: RL+RE) in 47% of days/year. Coverage area of DCI is estimated to be about 300km radius from the center point (over 280,000km2) that extracted from the mean of atmospheric wavelengths. Correlation coefficient between DCI and temperature (precipitation) in monthly scale is -81% (50%).