نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی دکتری آب و هواشناسی دانشگاه خوارزمی تهران، ایران
2 عضو هیات علمی و استاد دانشگاه خوارزمی تهران، ایران
3 استاد پژوهشگاه هواشناسی و علوم جو تهران، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
One of the patterns of major climate changes in tropical maritime regions is the Maden-Julian oscillation, which affects sub-seasonal time periods of 30 to 60 days, tropical and subtropical regions. This phenomenon brings the variability of various quantities of the atmosphere and the ocean, such as pressure, surface temperature, and the rate of evaporation from the ocean surface in tropical regions. In this research, first, the daily rainfall data of 48 synoptic stations, 1980-2020, was obtained from the Meteorological Organization. And quality control in three zero levels 1 and 2, including structural quality control, physical limits, correlation of parameters within the report, climatic range, temporal and spatial correlation, quality control.The Madden-Julian Oscillation is one of the large-scale climate change patterns in the maritime tropics, with subseasonal time periods of 30 to 60 days affecting tropical and subtropical regions. This phenomenon can cause changes in various quantities of the atmosphere and ocean, such as pressure, sea surface temperature, and the rate of evaporation from the ocean surface in tropical regions.In this research, the effects of Maden Julian fluctuation on the weather elements of Iran have been investigated with the aim of knowing the effects of different phases in order to improve the quality of forecasts and benefits in territorial planning. At first, the daily rainfall data of 1980-2020 was received from the National Meteorological Organization and quality controlled. Using the Wheeler and Hendon method, the two main components RMM1 and RMM2 were analyzed, based on which the amplitude of the above two components is considered as the main indicator of the intensity and weakness of this fluctuation. This index is based on the experimental orthogonal functions of the meteorological fields, including the average wind levels of 850 and 200 hectopascals and outgoing long wave radiation (OLR) between the latitudes of 20 degrees south and 20 degrees north. The clustering of the 7-day sequence with a component above 1 was used as the basis for clustering all eight phases, and by calculating the abnormality of each phase compared to its long term in the DJF time frame, the zoning of each phase was produced separately. In the end, phases 1, 2, 7, 8 were concluded as effective phases in Iran's rainfall and phases 3, 4, 5, 6 as suppressive phases of Iran's rainfall.Phases with a sequence of 7 days and a component above 1 were used as the basis for clustering all eight phases, and by calculating the abnormality of each phase compared to its long duration in the DJF time frame and by passing the data through the 30-60 day intermediate filter, zoning Each phase was produced in latitude 25 to 40 degrees north and longitude 44 to 63 east. With the investigations carried out and the output of the models and finally the production of zoning related to Iran's rainfall anomalies in the eight phases of the MJO, the country's daily rainfall data were analyzed in the period from 1980 to 2021, which finally after applying Data optimization filters, Iran's precipitation zoning output using Arc Gis software were produced separately for all eight phases. According to the outputs, the distribution of rainfall in the conditions of phase one can be seen with a variety of fluctuations, among which the share of rainfall and rainfall anomalies is greater in the southwestern and southern regions of Iran, especially in the regions of Fars, Hormozgan, West Kerman and Bushehr provinces. It is significantly different from other regions of Iran. In the region of the Caspian coast, the main reason for the rainfall is different from the rainfall in other regions of Iran, and it is not discussed in this analysis. Iran's rainfall anomaly in phase 2 has weakened compared to phase 1 of rainfall, and it can be felt that the anomaly is weaker in most areas. Iran's rainfall anomaly in Phase 3 of Madden Julian Oscillation has shown, we have significantly limited rainfall and almost locally. In phase 3, there is no rainfall in Iran, and obviously, with the beginning of the positive phase of the Madden Julian Oscillation, which includes phases 3, 4, 5, and 6, the changes in precipitation in Iran are different from the negative phases 1, 2, 7, and 8, and their changes can be considered in relation to each other.Eliminating the boundary between spatial-temporal scales and a deeper understanding of distant planetary systems is always an important challenge that the scientific community is facing. Undoubtedly, progress in medium-range and seasonal weather forecasting and our understanding of large-scale weather patterns and the identification of specific causes of their occurrence rely on our deep understanding of the behavior of atmospheric-oceanic patterns and their relationship with each other. to be Based on the direction of this research, the investigation of precipitation anomalies associated with the eight phases of MJO during the period of December, January and February 1980 to 2020 showed that the precipitation behavior of each of these phases is different from each other and the position, intensity and extent under the influence These abnormalities are variable in each phase.
کلیدواژهها [English]
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