Climatological Analysis of Extreme and Widespread Precipitations in Southeast of Iran

Document Type : Research Article

Authors

• M. Mohammadi ¹
• M. Akbary ²

¹ - M.Sc. of Climatology, Faculty of Geographical Sciences, Kharazmi University

² Associate Professor of Climatology, Faculty of Geographical Sciences, Kharazmi University

https://doi.org/10.22067/jsw.2022.68783.1024

Abstract

Introduction: Sistan and Baluchestan Province, in southeast of Iran, is covering about 11 percent of the whole space of the country but is one of the driest provinces in Iran and its average annual rainfall is about 110 mm. The purpose of this study was to identify large-scale atmospheric circulation patterns causing extreme and widespread rainfalls during the warm seasons (spring and summer) in southeast of Iran (Sistan and Baluchestan province).
Data and Methodology: Precipitation data of 6 synoptic stations of Sistan and Baluchestan province during a 30-year statistical period (1979-1998) were obtained from Meteorological Organization of Iran (IRIMO). The intensity of precipitation based on 90^th percentile threshold and widespread precipitation index of at least ≥50% of the studied area were calculated. To identify the synoptic patterns of the upper atmosphere, the ERA5 data of the ECMWF European Center of Med-Latitude Weather Forecast with spatial resolution of 0.25° × 0.25° were obtained. The collected atmospheric parameters included mean sea level pressure (mslp), geopotential height (z), specific humidity (q), zonal (U) and meridional (V) wind components, relative vorticity (rv) and omega (w) and maps of the upper atmosphere were drawn at different levels using Gards software in the domain of 10 to 70E and 10 to 90N. Regarding the two selected characteristics, three events of heavy and widespread precipitation were determined.
Results and Discussion: By analyzing the daily rainfall data over a period of 30 years (2018-1988) during the warm months of the year, the number of days with torrential and widespread rainfall in Sistan and Baluchestan province were determined. According to the index the previously defined floods and mudslides were obtained for 3 days with torrential and widespread floods that often occur in the spring, which are categorized to three main patterns including: 1- Gono Tropical Storm 2- Omega Blocking and 3 – 500 hpa trough system. The results showed that during the maximum 24-hour precipitation, in the first synoptic pattern, the southern cities of the province received the maximum precipitation due to the proximity of the storm’s core, but gradually from southern to northern latitudes, the rainfall declined considerably so that Chahbahar station had the maximum rainfall and Zabol station recorded zero rainfall. The storm is expected to move eastward as it moves to higher latitudes, but the high pressure formed on the Indian subcontinent acted as a barrier and directed the storm to the west, thus affecting the southern regions of Iran. In the second and third pattern, the location of Sistan and Baluchestan province in front of the trough axis and advection of cold weather of the northern latitudes were the main causes of instability that lead to heavy rainfall. The moisture of these rainfalls was obtained from Oman, Arabian Sea and Indian Ocean respectively. In the second pattern, the anticyclonic clockwise motions of the Arabian Sea has provided the moisture for extreme precipitation events. Common points of all three precipitation patterns are atmospheric moisture reduction in all three levels of the earth, 850 and 700 hectopascals from south to north of the province. This is mainly due to the distance from moisture sources as well as the arrangement and height of the roughness of Sistan and Baluchestan province, which has caused moisture trapping and prevented the transfer of sufficient moisture for the occurrence of torrential rains. In the second model, the amount of moisture reduction from south to north is less, which indicates the activity of the Arabian Sea high pressure and the power of this high pressure in moisture transfer. In general, with increasing altitude towards the northern regions, mainly rainfall systems have lost their moisture and unevenness has prevented the proper distribution of moisture in the province.
Conclusion: In southeastern Iran, the spatial distribution of precipitation is strongly influenced by the proximity to the sea and the location of the topographic features. Upper air levels turbulences are the most common cause of air mass rise. The main factor in reducing heavy rainfalls in northern areas of Sistan and Baluchestan is the lack of sufficient water vapor to reach these areas. Extreme rainfall is more likely to occur in spring than in summer due to the appropriate thermal gradient in southeastern Iran. Finally, the results of the study showed that the possibility of precipitation in spring compared to summer due to the appropriate temperature gradient in southeastern Iran and the activity of Siberian and Northern European high pressure, the conditions for fronting in these areas are provided. Since the humidity of the southern oceans through atmospheric rivers has been effective in the occurrence of heavy rainfall in southeastern Iran, rising temperatures in the southern oceans due to global warming can strengthen moisture flows in the future and from this route to affect the intensity of rainfall in southeastern Iran.

Keywords

• Extreme precipitation
• Sistan and Baluchestan
• Widespread precipitation

20.1001.1.20084757.1400.35.6.9.4

Main Subjects

• Irrigation

References

• Ahmadi M., and Jafari F. 2018. Complete Routing and Synoptic Analysis A Study Sample of Systems Leading to Heavy Rainfall of More Than 50 mm in Southern Iran, Journal of Spatial Analysis of Environmental Hazards, 5^th Year, No. 3: 83-102. (In Persian with English abstract)
• Akbary M. 2015. Combinatory Mediterranean-Sudanese systems role in the occurrence of heavy rainfalls (case study: south west of Iran), Meteorology and Atmospheric Physics, 2015, DOI:10.1007/s00703-015-0389-x.
• Akbary M., and Nodehi V. 2015. Analysis of trends in annual and summer rainfall of Golestan Province, Geographical Planning of Space Quarterly Journal 5(17): 141-150. (In Persian with English abstract)
• Alijani B., Hashemi-Ana S., Abbasnia M., and Pour Hashemi S. 2014. Analysis of Dynamic, Thermodynamic and Synoptic Conditions of Flood Precipitation in the dry Area of Southeastern Iran, Geography and Environmental Stability 13: 28-13. (In Persian)
• Alijani B. 2017. Climate of Iran, Payam-e-Noor Publication, Number of pages 236.
• Arabi Z. 2005. Synoptic analysis of rainfall from July 17 to 21, 1999 in Iran, Geographical Research, 56: 15-1. (In Persian)
• Ashley S.T., and Ashley W.S. 2008. Flood fatalities in the United States. Journal Appl. Meteor. Climatology 47: 805–818, https://doi.org/10.1175/2007JAMC1611.1
• Moore B., White A., Gottas J., and Neiman P. 2020. Extreme Precipitation Events in Northern California during Winter 2016–17: Multiscale Analysis and Climatological Perspective، Monthly Weather Review 148(3): 1049–1074.
• Borzoo F., and Azizi Gh. 2014. Proposing a simple criterion for estimating heavy rainfall in different regions of Iran, Natural Geography Research, Volume 47, and Number 3. (In Persian with English abstract)
• Chakraborty A. 2016. A synoptic-scale perspective of heavy rainfall over Chennai in November 2015, doi: 10.18520/cs/v111/i1/198-201.
• Dargahian F., Alijani B., and Mohammadi H. 2014. Synoptic study of pressure patterns associated with blocking affecting the occurrence of continuous rainfall (5 days and more) and heavy rains in Iran: in the cold season of 2012-1993. Geography and Environmental Hazards 10: 173-155. (In Persian)
• Dostkamian M., and Mirmousavi S.H. 2015. Analysis of Extreme Precipitation Clusters in Iran, Geography and Development 41: 146-131. (In Persian)
• Farajzadeh M. 2014. Climatic hazards of Iran, Samat Publications, number of pages: 348.
• Farajzadeh M. Moghli M., and Afshari Far M. 2016. Analysis of the role of monsoon systems in precipitation in southeastern Iran, Proceedings of the conference on geophysical development potentials in the oceanic coasts of southeastern Iran. (In Persian)
• Fritz Hermann M., Blount C.D., Albusaidi F.B., and Al-Harthy A.H. 2010. Cyclone Gonu Storm Surge in the Gulf of Oman. Indian Ocean Tropical Cyclones and Climatic Change Publisher; Springer; DOI: 10.1007/978-90-481-3109-9_30
• Ghaderi H., and Alijani B. 2010. Synoptic Analysis of Larestan Severe Precipitations, Journal of Physical Geography, Third Year, No. 8, Summer 2010. (In Persian with English abstract)
• Jennrich G.C., Furtado J.C., Basara J.B., and Martin E. 2020. Synoptic Characteristics of 14-Day Extreme Precipitation Events across the United States, Journal Climate 33(15): 6423–6440.
• Islamic Republic of Iran Meteorological Organization (IRIMO); Office of National Reference of the International Pannel of Climate Change (IPCC) of the Climatological Research Institute - Mashhad, in collaboration with: National Center for Drought and Crisis Management of the Meteorological Research Institute. Detection, evaluation of the effects and prospects of climate change in Iran during the 21st century, 2017.
• IPCC, Climate Change. 2014. Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Field, C.B., Barros V.R., Dokken D.J., Mach K.J., Mastrandrea M.D., Bilir T.E., Chatterjee M., Ebi K.L., Estrada Y.O., Genova R.C., Girma B., Kissel E.S., Levy A.N., MacCracken S., Mastrandrea P.R., and White L.L. (eds.), Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1132 pp., 2014.
• Glisan J.M., Gutowski Jr W.J., Cassano J.J., Cassano E.N., Mark W., Kharin V.V., and Zwiers F.W. 2005. Estimating extremes in transient climate change simulations. Journal Climate 18: 1156– 1173.
• Khosravi M. 2019. A Survey on the of the Summer Precipitation Events Moisture Supply Resources of Southeast of Iran. 12(41): 127-144.
• Lashkari H. 2005. Synoptic Analysis of two patterns of winter rainfalls in southeast of Iran, Modarres Quarterly, Volume 9, Number 1, Spring 2005. (In Persian with English abstract)
• Lashkari H., and Khazaei M. 2014. Synoptic analysis of heavy rainfall in Sistan and Baluchestan province, Sepehr Geographical Information Journal 23(1-90): 70-85. (In Persian with English abstract)
• Luo Y., Mengwen W., Fumin R., Jian L., and Wai-Kin W. 2016. Synoptic Situations of Extreme Hourly Precipitation over China, Journal of Climate.29; 24, 8703-8719. DOI: 10.1175/JCLI-D-16-0057.1.
• Mafakheri O., Saligheh M., Alijani B., and Akbary M. 2016. The Hazards of Rainfall Concentration in Iran. Journal of Geography and Environmental Hazards 6(3): 143-162. (In Persian with English abstract)
• Meehl G.A., Covey C., Delworth T., Latif M., McAvaney B., Mitchell J.F.B., Stouffer R.J., and Taylor K.E. 2007. The WCRP CMIP3 multimodel dataset: A new era in climate change research. Bull. Amer. Meteor. Soc., 88: 1383–1394.
• Wu M., Wu C.C., Yen T.H., and Luo Yali. 2017. Synoptic Analysis of Extreme Hourly Precipitation in Taiwan during 2003–12، Journal of Monthly Weather Review 145(12): 5123–5140.
• Montazeri M., Nami M.H., and Dalaei H. 2013. Synoptic Analysis of Heavy Rainfall November 21, 2011. Kohkiluyeh and Boyer-Ahmad Province Sarzamin Geographical Journal; 10, 37; 77-89. (In Persian with English abstract)
• Omidvar K., and Torki M. 2013. Identifying patterns of heavy rainfall in Chaharmahal and Bakhtiari province, The Journal of Spatial Planning, 16(4): 135-170. (In Persian)
• Parand Khorani A., and Lashkari H. 2011. Heavy Storms in Southern Iran (Case Study of December 31, 1984 to January 4, 1985, Dalaki River Watershed, Journal of Geography and Environmental Planning, 22(41): 136-123. (In Persian)
• Bohlinger P., Sorteberg A., and Sodemann A. 2017. Synoptic Conditions and Moisture Sources Actuating Extreme Precipitation in Nepal, Journal of Geophysical Research: Atmospheres, 122, 12,653–12,671. https://doi.org/10.1002/2017JD027543
• Pourasghar F, Jahanbakhsh S, Sari Sarraf B., Ghaemi H., and Tadayoni M. 2012. Zoning of precipitation regime in the southern half of Iran, Journal of Geography and Planning 17(44): 26-46.
• Rahimi D., Khoshhal J., and Alizadeh T. 2010. Statitistical-Synoptic Analysis of Heavy Precipitations of Dry Lands, Journal of Geography and Regional Planning, No. 14. (In Persian)
• Rastgoo Z., and Ranjbar Saadatabadi A. 2018. Study of heavy and moderate rainfall in Bushehr province from a synoptic-dynamic perspective, Journal of Meteorology and Atmospheric Sciences, 1(1): 96-77. (In Persian with English abstract)
• Rasouli A.A. 2004. Modeling of lightning in Tabriz city from the perspective of flood risk, International Conference on Natural Disasters, 5-7 October 2004, University of Tabriz. Schumacher, R. S., and R. H. Johnson, 2006: Characteristics of U.S. extreme rain events during 1999–2003. Wea. Forecasting, 21: 69–85. (In Persian)
• Saliqeh M. 2001. Synoptic Patterns of Summer Precipitation in Southeastern Iran, Geographical Research Quarterly, Article Number: 521. (In Persian)
• Saliqeh M. 2005. Precipitation mechanism of the southeast of the country, Journal of Physical Geography Research-No. 55. (In Persian)
• Špitalar M., Gourley J.J., Lutoff C., Kirstetter P.-E., Brilly M., and Carr N. 2014. Analysis of flash flood parameters and human impacts in the US from 2006 to 2012. Journal of Hydrology., 519: 863–870, https://doi.org/10.1016/j.jhydrol.2014.07.004
• Tebaldi C., Hayhoe K., Arblaster J.M., and Meehl G.A. 2006. Going to the extremes: An intercomparison of model-simulated historical and future changes in extreme events. Climatic Change 79: 185–2113.
• Vahdani I. 2013. Book of Weather and Climatology, First Issue. Aeezh Publication.
• Yu M., Miao S., and Li Q. 2016. Synoptic analysis and urban signatures of a heavy rainfall on 7 August 2015 in Beijing, Journal of Geophysical Research: atmospheres,122: 65-78., https://doi.org/10.1002/2016JD025420.
• Zwiers F.W., and Kharin V.V. 1998. Changes in the extremes of the climate simulated by CCC GCM2 under CO₂ Journal Climate 11: 2200–2222.