پديد آورندگان :
ﻧﻌﯿﻤﯽ، ﻣﺮﯾﻢ ﺳﺎزﻣﺎن ﺗﺤﻘﯿﻘﺎت آﻣﻮزش و ﺗﺮوﯾﺞ ﮐﺸﺎورزي - مو ﺳﺴﻪ ﺗﺤﻘﯿﻘﺎت ﺟﻨﮕﻞ ﻫﺎ و ﻣﺮاﺗﻊ ﮐﺸﻮر، ﺗﻬﺮان , ﻣﯿﺮاﮐﺒﺮي، ﻣﺮﯾﻢ داﻧﺸﮕﺎه ﺗﻬﺮان - داﻧﺸﮑﺪه ﻣﻨﺎﺑﻊ ﻃﺒﯿﻌﯽ، ﺗﻬﺮان , ﺧﺴﺮوﺷﺎﻫﯽ، ﻣﺤﻤﺪ ﺳﺎزﻣﺎن ﺗﺤﻘﯿﻘﺎت آﻣﻮزش و ﺗﺮوﯾﺞ ﮐﺸﺎورزي - مو ﺳﺴﻪ ﺗﺤﻘﯿﻘﺎت ﺟﻨﮕﻞ ﻫﺎ و ﻣﺮاﺗﻊ ﮐﺸﻮر، ﺗﻬﺮان , زﻧﺪي ﻓﺮ، ﺳﻤﯿﺮا ﺳﺎزﻣﺎن ﺗﺤﻘﯿﻘﺎت آﻣﻮزش و ﺗﺮوﯾﺞ ﮐﺸﺎورزي - مو ﺳﺴﻪ ﺗﺤﻘﯿﻘﺎت ﺟﻨﮕﻞ ﻫﺎ و ﻣﺮاﺗﻊ ﮐﺸﻮر، ﺗﻬﺮان , ﻗﺎﺳﻤﯽ آرﯾﺎن، ﯾﺎﺳﺮ ﺳﺎزﻣﺎن ﺗﺤﻘﯿﻘﺎت آﻣﻮزش و ﺗﺮوﯾﺞ ﮐﺸﺎورزي - مو ﺳﺴﻪ ﺗﺤﻘﯿﻘﺎت ﺟﻨﮕﻞ ﻫﺎ و ﻣﺮاﺗﻊ ﮐﺸﻮر، ﺗﻬﺮان
چكيده لاتين :
Climatic components are the vital factors influencing the dust event. It was believed that changes
in climate parameters play a crucial role in the occurrence of dust events. Former studies have shown that
temperature, rainfall, and wind speed contribute to poor vegetation, providing requirements of dust events. Longterm
dust data indicated that climate has a profound effect on dust events and the occurrence of dust storms
compared to the desertification process (Zhang and Anastasio, 2003). Monitoring Iran’s meteorological data
indicates changes in precipitation and temperature in the last two decades (Rezaei and Ghasemieh, 2019).
Alterations in the amount and pattern of rainfall and rising temperature can initiate the changes that cause natural
hazards, including dust storms. Hence, in the present study, the trend of changes in climatic parameters in
Khorasan Razavi province has been investigated. Note that the climatic parameters are consisting of rainfall,
average temperature, wind speed, and frequency of erosive winds.
Material and methods: According to the objectives of the present study, the monthly precipitation, temperature,
and wind speed of seven synoptic stations including, Mashhad, Sabzevar, Sarakhs, Neishabour, Torbat
Heydariyeh, Kashmar, and Quchan, were obtained from the meteorological organization of Khorasan Razavi
from 1990 to 2016. Hourly dust codes also were extracted to detect the number of dusty days in the study period. The relationship between climatic parameters of precipitation, temperature, wind speed, and erosive wind
frequency was inspected by the Pearson correlation coefficient for each station. Later, the trend of dust events
and climatic parameters was analyzed using the Mann-Kendall trend test.
Results and discussion: Results of dust codes indicated the local origin for the highest frequency of dusty days.
Even though Sarakhs and Mashhad stations had the highest dusty days, Quchan and Kashmar had the lowest one
in the study region. The Mann- Kendall test pointed out an increase in temperature for all study stations except
Neishabour. Meanwhile, the precipitation had a downward trend in the Mashhad, Kashmar, Sabzevar, Torbat
Heydariyeh, and Sarakhs stations and an increasing trend in the Neishabour and Quchan. Raising the frequency
of the erosive wind in Quchan, Kashmar, Sabzevar, Sarakhs, and Neishabour stations during the study period
could also be stated. In most of the stations (except Mashhad and Neishabour) upward tendency in the number of
dusty days is consistent with other researchers such as Mehrshahiand Nekounam (2009) in Sabzevar, Boochani,
and Fazeli (2011) in Ilam, Shahsavani et al. (2011) in Khuzestan stated. Hence, the decreasing tendency of dusty
days in Mashhad and Neishabour is also in line with Rafiei et al. (2015) in Yazd, Semnan, Kashan, Ramsar, and
several other stations. The falling trend of wind speed in Mashhad station can be reflected as the main reason for
the reduction of dust events. In addition, the rising tendency of precipitation and possible decline of drought in
Neishabour can be considered as the main reasons for the decrease in the number of dusty days. To understand
the effect of climatic factors on the occurrence and intensification of dust events, the relationship between the
number of dusty days and climatic parameters was determined. The results of correlation analysis between dust
events and climatic parameters showed that the temperature directly affects the dust events in all stations except
Mashhad. The positive correlation between temperature and dust events was stated in other studies (Bahrami et
al., 2013; Amgalan et al., 2017). The correlation coefficient between dust event and precipitation showed a
negative relationship between them which was significant at 95% level in Sarakhs station. Other studies (Ali et
al., 2016; Broomandi et al., 2017; Amgalan et al., 2017) have also indicated the inverse effect of precipitation on
dust events, which is following the findings of this study. The results of correlation analysis between the number
of dusty days and wind speed and the frequency of erosive wind showed that the enormous influence on dust
events is wind speed. While, at Neishabour station, there is a significant negative relationship between dust and
wind speed. Indeed, the inverse relationship between dust and wind speed indicates that with increasing wind
speed, the dust emission does not increase and another factor reduces the effect of wind speed. As Kimura
(2012) reported the impact of vegetation on reducing the wind speed impact on the dust occurrence.
Conclusion: It was proven that the number of dusty days is in line with the variations of the climatic parameters.
The decrease in rainfall, increase in temperature, and wind speed has been accompanied by an increase in dusty
days in the region. In general, correlation analysis of dusty days and climatic parameters in Khorasan Razavi
province indicated that wind speed and the frequency of erosive wind have considerable influence on dust
events. However, the effect of wind speed on dust events at the Neishabour station reflected the significance of
vegetation cover on reducing the transfer of soil particles.
