نوع مقاله : مقاله پژوهشی
عنوان مقاله English
نویسندگان English
The large-scale atmospheric circulation system, which shapes global and regional climates, derives its required energy from the suns output. However, the temporal trend of solar energy output is not constant or uniform over time; rather, it follows relatively regular cycles dependent on the photochemical processes of the sun. Variations in this energy are associated with the appearance of sunspots on the solar atmosphere. In this study, the relationship between annual precipitation at synoptic stations in Greater Khorasan Province and fluctuations in the number of sunspots was examined and compared over the three most recent solar cycles Using the relationship between total annual precipitation and the number of sunspots by comparing sinusoidal curves and the eleven-year average of precipitation. The findings revealed that during Cycles 22 and 23, which exhibited normal solar cycle conditions, precipitation exceeded the cycle’s average in two distinct periods: the first two years and the final two years of each cycle. During these intervals, most stations recorded above-average rainfall, particularly at northern stations, where the effect was more pronounced. Conversely, in the years between the solar maximum and minimum, precipitation generally decreased, falling below the cycle’s average. However, in the third cycle (Cycle 24), which was an exceptional cycle in the last century—marked by the lowest recorded number of sunspots during both its peak and minimum phases—the pattern differed. While above-normal precipitation occurred at the beginning and end of the cycle, mid-cycle rainfall at most stations remained below the cycle’s average.
کلیدواژهها English
