Investigating the Relationship between heavy rainfall west of Iran and Atmospheric Rivers

Abstract

Introduction
Precipitation, as one of the important climatic elements, has certain complexities, and usually the precipitations of one point in different time scales do not have simple and symmetrical statistical distributions (Asgari and Rahimzadeh, 2015). Reducing or increasing the amount of rainfall has an effect on many other climatic and environmental phenomena such as runoff, floods, air temperature, humidity, and also on many human activities (Gandhamkar and Khadem al-Hosseini, 2018). Therefore, it can be seen that the change in the amount and regime of rainfall can be a sign of climate change. The issue of climate and its change is an irreversible situation, and one of its manifestations and consequences is the change in climatic elements, especially temperature and precipitation in different regions (2001, IPCC). One of the most important changes in the climatic elements is the rainfall extremes, which according to atmospheric scientists, climate change has not only caused an increase in the rainfall extremes, but also increased the intensity of these rainfalls (Narimani and Daran, 2019). Therefore, it is very important to know the mechanisms governing these precipitations. Therefore, in this study, an attempt has been made to identify the atmospheric conditions governing these types of precipitation. In recent years, the effect of an atmospheric phenomenon called atmospheric rivers in causing heavy rains in some parts of the world such as Europe and the United States has attracted the attention of atmospheric scientists, which shows that atmospheric rivers play a very important role in providing The humidity of these rains has been (Shadamani et al., 2015). As a result, in this study, it has been attempted to examine the effects of the Joy River and the conventional conditions of heavy rainfall western Iran.

Methodology
The main purpose of this study was to investigate the atmospheric structure of the west of the country, emphasizing the effects of the atmospheric river on such rainfall. As a result, environmental attitudes have been used to achieve this goal. The reason for this approach is that the time and spatial changes are much more severe than other climatic variables, so the circulation approach to the environment often fails to explain atmospheric falls (Mirmosavi et al. 1399). In fact, the choice of this approach allows the researcher to focus only on precipitation and consequently synthetic types that are associated with the phenomenon of precipitation (Masoudian, 2011: 51). Therefore, in the first step, the daily rainfall data for the years 1990 to 2019 is from the country's meteorological organization, which creates a matrix of 10957 (32) (32 indicating the number of stations and 10957 representing the number of stations and 10957. The number of days is the day. Then, considering the two main conditions of one: Extraction of heavy precipitation threshold based on the 95th -by -95th: The heavy rainfall based on the 95th percense was at least 30 % of the stations were extracted. Used to analyze the atmospheric atmospheric database of the US Oceanic and Oceanic Climate (NCEP/NCAR) with 2.5 x 2.5 degrees of arc and geoptt altitude of 1000 and 500 hectopskal, The orbital and meridian components of the 1000, 850 and 500 hectops and the special moisture of 850 for 10 degrees west to 80 degrees east and zero to 80 degrees North were obtained from this base and to identify the atmospheric rivers. The integrated data of the vertical vapor flux (East and North of the Horizontal Water Vapor Transport (IVT)) has been used by the European Middle Ages Preference Center (ECMWF) with 0.5 degree arch. The integrated data of the vertical water vapor flux, including special sprinkle, orbital, and meridian, from 1000 to 300 hectop barley levels, are calculated in the Utiller device as follows (Relation 1).

In this respect, IVT indicates the vertical water vapor flux, q indicates a special kg per kg (kg kg^(-1)) U and V orbital and half-enclosure components per second (m s^(m s^ 1)), G is a acceleration and DP is the difference between the two levels. (Lavers et al, 2012; Ramos et al 2015) In the present study, to accurately examine the effects of the riverbank and carefully analyze the weather conditions affecting heavy rainfall, classify corresponding days with heavy rainfall data based on sea pressure data Using the mergers' analysis method, then to analyze the effects and identify the effects of the atmospheric river, to provide average atmospheric and IVT data for each group and separately the entry route of each atmospheric river for each identified group.
Conclusion
This study was aimed at investigating the relationship between heavy rainfall and the Joy River and its synergy analysis. To this end, the daily precipitation data of 32 synoptic stations with the same statistical period during 1990 to 2019 were obtained from the Meteorological Organization, then the criterion for extracting the days with heavy rainfall of 95, 95th per station occurred at least 30 % at least 30 %. The stations were found and it was found that 52 heavy rainfall cases were taken into account with the above two conditions. Then, for better understanding of the clustered analysis by integrating methods, the sea pressure alignment data for 52 days was heavy with heavy rainfall, and the results showed that these rainfalls were investigated in three major groups, followed by more and more. The average for each group has been analyzed and identified by the Joy River, and in the final step of the Joy River movement is drawn for each group.
In all three patterns, there is always an interaction between the two high-pressure Siberian-European centers with Sudan and Iceland's low pressure. In most cases, the high -pressure Siberian and European compactness has merged with one another in its orbital expansion and created a high -pressure belt. Siberian high -pressure and high -profile European pressure, both at the time of integration with unity and at the time of confrontation with Iceland, has been drawn to the Arab and North African Sea, respectively, each strengthened the Sudanese low pressure, respectively, respectively. . Siberian high -pressure tongues on the Arabian sea have paved the way for strengthening and even creating a high -pressure cell on the Arabian sea. The airflow showed that the two high -pressure Siberian and European tongues have transmitted the Arabian Sea, the Oman Sea and the Mediterranean into the Sudanese low -pressure, and given the low dynamic nature of the Sudanese Pressure, the field of activity and movement. Outside the normal conditions, it has exacerbated the movement of the atmosphere. The arrangement of air flows and curves in the lower and middle levels of the atmosphere well proves and proves the role of the Arab Sea, the Red Sea, the Persian Gulf and to some extent the Oman Sea and the Mediterranean Sea in supplying heavy rainfall western Iran. It can be said that a strong convergence of the moisture of the aforementioned water resources is created from the lower to the middle of the atmosphere and has paved the way for the creation of the atmospheric river. In the study, 52 heavy rainfall cases were observed in all cases with a river from East Africa and extended to the western parts of Iran, confirming this issue of the movement of the Joy River in all three groups. In the first group, the main origin of the rivers from East Africa started, but in the second and third group we saw another route from the Mediterranean that increased the rainfall so that the average rainfall of the first group was 18.81 mm and in the second and third group. Respectively reached 18.61 and 19.50 mm.