Document Type : Research Paper
Authors
1 Professor of Climatology, Department of Physical Geography, Faculty of Social Sciences, University of Mohaghegh Ardabili, Ardabil, Iran.
2 Ph.D. Student of Climatology, Department of Physical Geography, Faculty of Social Sciences, ‎University of Mohaghegh Ardabili, Ardabil, Iran
Abstract
Objective: In the present study, the relationship between the Madden-Julian Oscillation (MJO) index during the dominance of its different phases and the climate patterns prevailing in the Persian Gulf and the Sea of Oman during the period 1994 to 2023 was investigated.
Research Method: MJO index data were obtained from the Australian Bureau of Meteorology website and the eight phases of this index were separated. The days of the MJO were selected with a sequence of more than 15 days and the arrangement of each phase was plotted with the Wheeler and Hendon diagram in MATLAB software. Data related to precipitation, air temperature, Sea Surface Temperature, Sea Level Pressure, geopotential height, cloud density and Outgoing Longwave Radiation (OLR) were obtained from the NOAA website and changes in climate patterns during the dominance of each phase were examined.
Results: Phases 1 and 2 of the Madden-Julian oscillation have the highest number of continuous sequences with a duration of more than 15 days, with 9 events. The study of the OLR showed that within the activity range of each of these phases, the amount of radiant energy at the earth's surface has decreased to a minimum. This situation has led to the strengthening of convective activities and an increase in cloud density in these areas. During all periods of the dominance of the eight phases of the Madden-Julian oscillation, the presence of a thermal low-pressure system has been observed in the study area.
Conclusion: The phased Madden-Julian Oscillation has had a significant impact on the climatic patterns of the Persian Gulf and the Sea of Oman. In phases 1, 2 and 5, the phenomenon of blocking over the studied area has dominated and by blocking warm and dry air, the sea surface temperature has increased and the amount of precipitation has decreased.
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