@article{MAKHILLIJTM202015319995,
    title = {The Study of Frequencies of High-Amplitude Ridge Blocks with Incidence of Falls Droughts
over Iran (Case Study: Between 1976-2005)},
    journal = {International Journal of Tropical Medicine},
    volume = {15},
    number = {3},
    pages = {47-51},
    year = {2020},
    issn = {1816-3319},
    doi = {ijtmed.2020.47.51},
    url = {https://makhillpublications.co/view-article.php?issn=1816-3319&doi=ijtmed.2020.47.51},
    author = {Leila,Hasan and},
    keywords = {Air pollution,climatology,drought,environment,agriculture},
    abstract = {Drought is a complex and dissonant natural
phenomenon which its intensity changes and its
occurrence take place slowly. This phenomenon is not
predictable and different factors such as geographical
location, atmospheric conditions, etc. are involved in its
occurrence. Drought adversely affects peoples living
conditions, economy and agriculture. Using monthly and
annual precipitation data received from Iran
Meteorological Organization and also data from National
Centre for Environment Prediction-National Centre for
Atmospheric Research (NCEP-NCAR) of the United State
and using statistical methods, three cases of autumn
drought periods in 1998, 1995 and 1996 have been
identified and using synoptic maps received from this
centre, atmospheric flow patterns, including high-pressure
and low-pressure were studied. Maps used in this study
are the daily maps with levels of 500 and 1000 HP in a
network with a single degree latitude and longitude
including 00-75 Northern degrees and 00-90 Eastern
degrees. According to the statistical analysis conducted in
this thesis, for different stations (31 stations) during the
30-years period, the results display a very dry climate in
most of the stations and the order of dry years is as
follows: 1998, 1995, 1996, 1983 and 1990. Among these
years, we had a very little rainfall in the autumn of 1998,
1995 and 1996 in most of the stations. It was due to a high
amplitude blocking ridge on Iran region which we had
studied and discussed in this study.}
    }