Why is Iran’s rainfall less?
According to Ekhtaz Online report, quoting from Fars, rainfall plays a decisive role in Iran due to its dry and semi-arid weather conditions. This rainfall is very important for various aspects of the ecosystem, economy, agriculture and general welfare of the country. The water year starts from the beginning of the autumn season and ends at the end of the summer season of the following solar year. For a long time, the dominant profession of Iranians has been agriculture or jobs related to it. According to the data, the surface of half of the crops is dry land.
The Sudanese low pressure system is one of the precipitation systems that has a direct impact on some regions of Iran. Rainfall in the geography of Iran has always been a concern among people and rulers. Livelihood and fear of hunger and preservation of survival are the factors that focus agriculture in the long term with preference and distinction. In different periods of time, several systems are effective in Iran, such as: Sudanese, Mediterranean, Siberian, Indian subcontinental monsoon, European migrant, monsoon and El Nino, which can rule over drought and drought conditions in Iran.
Due to the dryness of Iran’s climate, rainfall is absolutely vital to maintain the sustainability of the environment, economic prosperity and the well-being of our countrymen. Effective water management, conservation and sustainable agricultural practices are crucial to maximize the benefits of rainfall in the country. Rainfall is the most important variable whose changes are directly reflected in soil moisture, surface currents, and underground water. These variables have a direct relationship with the rainfall systems entering Iran as well as the moisture sources that inject moisture into the systems. One of the most effective cold systems of the year over Iran is the Sudanese low pressure system, which is called the Sudanese wave in some sources. This system is one of the components of the general circulation of the atmosphere in the southwestern regions of the Red Sea, between Sudan and Ethiopia, which is formed over the west of Ethiopia and the country of Sudan during most of the year.
The existence of this system remains constant over the mentioned region from the beginning of October to the end of May, and with the easterly currents, especially in the lower layers of Ward Sepehr, from the Gulf of Aden or from the eastern regions of Somalia, the warm and humid air of the Gulf of Aden and the western Indian Ocean towards the center Sudanese low pressure transmits. This low pressure has warm conditions during the mentioned months and is formed as a low pressure tongue between the high pressure located over North Africa and the high pressure located over the Arabian Peninsula.
The activation of this system is directly related to the eastern Mediterranean trough and according to its scope, the said low pressure can be in the form of a return letter from the Red Sea or in the form of a dynamic low pressure wave and with a diagonal movement towards the southwest to southeast regions. Iran will be transferred; Therefore, with what was described above, the activation of this system from thermodynamic to dynamic and its movement towards the north or northeast regions and the proper supply of moisture into this system causes precipitation in the southern half of Iran.
The survey conducted on 200 Sudanese systems in a statistical period of 20 years (1969-1989) showed that Sudanese systems enter Iran from five main ways and cause rainfall according to the synoptic patterns. The first two routes are integrated with a Mediterranean roundabout and the other three routes enter the country independently. In the first path, the Sudanese systems merge with the Mediterranean system over Cyprus and the eastern Mediterranean and move from the west. In the second path, the Sudanese and Mediterranean systems are merged over Iraq and affect Iran from the west and southwest. In the remaining three routes that the Sudanese systems operate independently, in route A. Sudanese systems enter Iran from the north of Saudi Arabia, Kuwait and Khuzestan. on the way b. The systems affect Iran through North Arabia and Bushehr province. On the way c. Sudanese systems enter the country through the center of Saudi Arabia and Hormozgan province.
Experts believe that the role of the Sudanese rain system in the rains of the southern half or even the northern half of Iran is important and significant. Therefore, the drought and drought in the southern half of Iran is mostly directed towards this system and it determines the models of drought and drought. The rains from this system are not only effective in Iran, but also in the eastern areas of the Mediterranean and even in Turkey, and many studies have been conducted on this system both inside and outside the country. The behavior of the Sudanese system will show a different behavior due to the interference with other systems, which cannot necessarily be acknowledged that the Sudanese system will produce precipitation or other behavior.