خلاصة:
Investigating the statistical and synoptic status of a region's climate requires the use of statistics and data that have occurred daily and in real-time, taking into account some frequencies of the occurrence of that phenomenon. In the not-so-distant past, perhaps little attention was paid to upper atmospheric conditions, and only surface conditions were statistically analyzed; however, today, with the use of numerous techniques, specialized software, and remote sensing, researchers have been able to study atmospheric phenomena on a planetary and systemic level and identify climatic patterns. Precipitation is considered one of the most irregular climatic elements in semi-arid regions, especially since its specific occurrence conditions—particularly heavy rainfall, which often leads to floods—must be studied and considered in environmental planning. The investigation of precipitation occurrence conditions, especially heavy rainfall in the South Khorasan region, using statistical and synoptic methods along with the coordinated use of sea level pressure maps and 500 hPa level maps, is one of the features of this research. It is hoped that in the future, such applied research will receive more attention from researchers in this field.
ملخص الجهاز:
13 Heavy Rainfall In the general review of the extracted maps related to heavy rainfall in the region, the following points are observed almost commonly in all maps: which are as follows: 1- The presence of intense instability in the surface maps, indicating an unstable atmosphere over the region, and due to passing over moisture sources, especially the Persian Gulf, the Sea of Oman, and sometimes the Indian Ocean, sufficient moisture has been absorbed, creating suitable conditions for ascent and the precipitation process.
The presence of two factors: 1) The replacement of a low-pressure core over the region 2) The formation of a trough over the region has caused intense instability to be created in the region and, given the suitable moisture conditions, both the surface and upper-air systems have prepared a favorable ground for heavy rainfall in the region, covering the entire surface of the region.
3 Nahbandan 10 Khor 35 Qaen 15 Ferdows 44 Bashruyeh 26 / Figure 3: 500 hPa level map on April 25, 1995 / Figure 4: Surface zero level map on April 25, 1995 Figure (5 and 6) Map of February 22, 1996 The movement of the Saudi Arabian low pressure from the southwest toward Iran and the establishment of low pressure in the region, along with the presence of a sharp pressure gradient and the movement of air currents toward higher latitudes, has caused the formation of a front that forces moist air to ascend.
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