Climatology
Maryam Teymouri; Bromand Salahi; Mohammad-Ali Nasr Esfahani
Abstract
To study the cyclogenesis within the Mediterranean region in different phases of Madden-Julian Oscillation (MJO) during the cold season (November, December, January, and February) between 1989 and 2020, MJO index and mean sea level pressure data from the European Centre for Medium-Term Atmospheric Prediction, ...
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To study the cyclogenesis within the Mediterranean region in different phases of Madden-Julian Oscillation (MJO) during the cold season (November, December, January, and February) between 1989 and 2020, MJO index and mean sea level pressure data from the European Centre for Medium-Term Atmospheric Prediction, ERA5 section were utilized. For visualizing the frequency, depth, and tracking characteristics of cyclogenesis, the University of Melbourne method was used. The results showed that the strongest cyclones in the region formed in phases 8, 6, and 7, respectively, with a pressure less than 994 hPa. In terms of the frequency of cyclogenesis and the core of cyclones in the region, the highest and the lowest amount of cyclogenesis were related to phase 7 and 1, respectively. The results showed that phases 6 and 7 have the strongest central pressures, whereas phases 1, 3, and 5 have the weakest central pressures of the MJO phases. Phase 2 has the lowest value of central pressure and the highest average pressure is related to phase 5. The tracking of cyclones that formed within the Mediterranean region showed that most of the paths that ended in the western regions of Iran were in phases 2 and 8, whereas in other phases, these tracks had a southwest to northwest direction. These situations were the case during phases 3, 4, 6 and 7, which caused most of the cyclones formed in the cold season of the year to affect most of the north-western regions of Iran.
Saeed Jahanbakhsh Asl; Batool Zeynali; Tahereh Jalali
Volume 16, Issue 39 , May 2012, , Pages 25-49
Abstract
In this research amount of seasonal effect of the Mediterranean Sea surface temperature (MedSST) has been investigated on seasonal precipitation of East Mountainsides of Zagros and Iran Central basins. For this purpose, warm, cold and base periods were determined for dates of MEDSST[1] in statistics ...
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In this research amount of seasonal effect of the Mediterranean Sea surface temperature (MedSST) has been investigated on seasonal precipitation of East Mountainsides of Zagros and Iran Central basins. For this purpose, warm, cold and base periods were determined for dates of MEDSST[1] in statistics period of (197-2005) for every season. Then statistic Medians of precipitation were determined so as (Rw, RC and Rb)[2] in each period and for all stations. Theses medians in every season and period were compared to specify amounts of these effects. The results indicated when MedSST is colder than base in winter season, precipitation of winter increases in the studied regions, but the temperatures of warmer than base in autumn increase autumn precipitation. Also MEDSST of colder than base of autumn is the cause of precipitation increase in winter and MEDSST of warmer than base of summer is cause of precipitation increase in autumn. The results of correlation analysis indicated that between oscillations of MEDSST and precipitation in winter there is negative correlation, in autumn it is positive correlation and between oscillations of MEDSST in autumn season and precipitation in winter season there is negative correlation. Between anomalies of MEDSST in summer and precipitation of autumn there does not exist any relevant correlation but between increases of autumn precipitation of the study region and warmer than normal MedSST of summer season the trends exist.
[1]- Mediterranean Sea Surface Temperature (MEDSST).
[2]- Rain Median of Warm period, Rain Median of Cold period and Rain Median of Base period of Mediterranean SST.
