تحلیل فضایی مخاطرات محیطی

تحلیل فضایی مخاطرات محیطی

واکاوی همدیدی دوره های خشک تابستانه سواحل جنوبی دریای خزر و رابطه آن با گردش های وردسپهری

نویسندگان
محمود روشنی 1
محمد سلیقه 2
بهلول علیجانی 2
زهرا بیگم حجازی زاده 2
1 -دانشگاه خوارزمی
2 دانشگاه خوارزمی
10.61882/jsaeh.12.1.45.1
چکیده
در این پژوهش الگوهای همدیدی دوره گرم سال که باعث توقف بارش و ایجاد دوره­های خشک کوتاه تا ابرمدت می­شوند مورد شناسایی و واکاوی قرار گرفتند. بدین منظور از آمار 8 ایستگاه همدید برای شناسایی دوره­های خشک فصل گرم بمدت 30 سال (1986 تا 2015) استفاده گردید. میانگین بارش روزانه دوره هر ایستگاه بعنوان مقدار آستانه جهت تفکیک دوره­های تر و خشک بکار رفت. سپس با توجه به آثار دوره­های خشک، اقدام به تعریف ذهنی و عینی آنها با مدتهای مختلف گردید. بدین ترتیب 5 دوره عددی 12 تا 15، 15 تا 30، 30 تا 45، 45 تا 60 و بیشتر از 60 روز مشخص شد. با تحلیل عاملی داده­های ارتفاع ژئوپتانسیل تراز 500 هکتوپاسگال، 4 مولفه برای هر دوره و در مجموع 20 مولفه برای 5 دوره خشک شناسایی شد. در مجموع 5 الگوی مشترک شرایط پایدار جوی دوره­های خشک را کنترل می­کنند. بطوریکه بیشتر روزهای خشک دوره گرم سال در اثر سیطره هسته پرارتفاع جنب حاره ایجاد می­شوند، که دارای آرایش گسترده، زوجی، دو هسته­ای، سه هسته­ای، جای­گزیده هستند. برخی از روزهای خشک منطقه در اثر زبانه پرارتفاع جنب حاره ایجاد می­شوند که اثر پرارتفاع جنب حاره در خشکی هوای ساحل جنوبی دریای خزر کاملا محرز است. بقیه روزهای خشک در اثر جنوبی شدن جریانات، تضعیف جریانات شمالی و منطقه واچرخندی ناوه ایجاد شدند. همچنین بررسی نقشه آنومالی مولفه­ها و خطوط هم­ارتفاع روز نماینده در تراز 500 هکتوپاسگال نشان داد که آنتی­سیکلونها یا واچرخندها با فاز مثبت و سیکلونها یا چرخندها با فاز منفی آنومالیها هماهنگ هستند.
کلیدواژه‌ها
سطح آستانه
دوره های خشک
تحلیل عاملی
الگوهای همدید
سواحل جنوبی دریای خزر

عنوان مقاله English

Synoptic Analysis of Summer Dry Spells in Southern Coasts of the Caspian Sea and Its Relationship with Atmospheric Circulation

نویسندگان English

Mahmoud Roshani 1
Mohammad Saligheh 2
Bohlol Alijani 2
Zahra Begum Hejazizadeh 2
1 -
2 Kharazmi University
چکیده English

In this study, the synoptic patterns of the warm period of the year that lead to the cessation of rainfall and the creation of short to long dry spells were identified and analyzed. For this purpose, the rainfall data of 8 synoptic stations were used to identify the dry spells of the warm season for 30 years (1986 to 2015). The average daily rainfall of each station was used as the threshold value to distinguish between wet and dry spells. Then, according to the effects of dry spells, they were defined subjectively and objectively with different durations. Thus, 5 numerical periods of 12 to 15, 15 to 30, 30 to 45, 45 to 60 and more than 60 days were identified. By factor analysis of Geopotential height data at 500 hPa, 4 components were identified for each period and a total of 20 components for 5 dry spells. Therefore, 5 common patterns control the stable weather conditions of dry spells. Most dry days are caused by subtropical high-pressure nuclei, which have a wide, even, dual-core, triple-core arrangement. The effect of subtropical high pressure on the dryness of the southern coast of the Caspian Sea is quite evident. Other dry days were caused by southerly currents, weakening of northern currents, and the trough Anticyclones’ area. Also, the anomaly map of the components days at the 500 hPa level showed that the anticyclones and cyclones correspond to the positive and negative phases of the anomalies, respectively.

کلیدواژه‌ها English

Threshold level
dry spells
Factor analysis
synoptic patterns
southern coasts of the Caspian Sea
Mathugama, S. C.; T. S. G. Peiris. 2011. Critical Evaluation of Dry Spell Research. International Journal of Basic & Applied Sciences, 11 (6): 153-160.
سلیقه، محمد. 1395. آب و هواشناسی سینوپتیک ایران. انتشارات سمت. چاپ اول. پاییز 1395. صص 202 تا 211.
Cook, G. D.; R. G. Heerdegen. 2001. Spatial variation in the duration of the rainy season in monsoonal Australia. International Journal of Climatology, 21: 1723-1732. [DOI:10.1002/joc.704]
نایبی، هوشنگ. 1393. آمار پیشرفته کاربردی همراه با Spss. انتشارات دانشگاه تهران. چاپ دوم. ص 229 تا 252.
Lund, I. A. 1963. Map - pattern classification by statistical methods. Journal of applied meteorology, 2: 56-65.
https://doi.org/10.1175/1520-0450(1963)0022.0.CO;2 [DOI:10.1175/1520-0450(1963)0022.0.CO;2]
منصورفر، کریم. 1388. روش‌های پیشرفته آماری همراه با برنامه‌های کامپیوتری. انتشارات دانشگاه تهران. چاپ سوم. ص 254 تا 255.
Kalkstein, L. S.; G. Tan, and J. A. Skindlov. 1987. An evaluation of three clustering procedures for in synoptic climatological classification. Journal of climate and applied meteorology, 26: 717-730.
https://doi.org/10.1175/1520-0450(1987)0262.0.CO;2 [DOI:10.1175/1520-0450(1987)0262.0.CO;2]
Mathugama, S. C.; T. S. G. Peiris. 2011. Critical Evaluation of Dry Spell Research. International Journal of Basic & Applied Sciences, 11 (6): 153-160.
Sheridan, S. C. 2002. The redevelopment of a weather-type classification scheme for North America. International journal of climatology, 22: 51-68. DOI: 10.1002/joc.709. [DOI:10.1002/joc.709]
Cook, G. D.; R. G. Heerdegen. 2001. Spatial variation in the duration of the rainy season in monsoonal Australia. International Journal of Climatology, 21: 1723-1732.
Bhalme, H. N.; D. A. Mooley. 1980. Large-scale drought/floods and monsoon circulation. Monthly weather review. 108: 1197-1211.
https://doi.org/10.1175/1520-0493(1980)1082.0.CO;2 [DOI:10.1175/1520-0493(1980)1082.0.CO;2]
Lund, I. A. 1963. Map - pattern classification by statistical methods. Journal of applied meteorology, 2: 56-65.
Pena, M.; M. W. Douglas. 1998. Characteristics of Wet and Dry Spells over the Pacific Side of Central America during the Rainy Season. Monthly weather review, 130: 3054-3073.
https://doi.org/10.1175/1520-0493(2002)1302.0.CO;2 [DOI:10.1175/1520-0493(2002)1302.0.CO;2]
https://doi.org/10.1175/1520-0450(1963)0022.0.CO;2 [DOI:10.1175/1520-0450(1963)0022.0.CO;2]
Mo, K. C.; J. N. Paegle, and R. W. Higgins. 2001. Atmospheric Processes Associated with Summer Floods and Droughts in the Central United States. Journal of climate, 10: 3028-3046.
https://doi.org/10.1175/1520-0442(1997)0102.0.CO;2 [DOI:10.1175/1520-0442(1997)0102.0.CO;2]
Kalkstein, L. S.; G. Tan, and J. A. Skindlov. 1987. An evaluation of three clustering procedures for in synoptic climatological classification. Journal of climate and applied meteorology, 26: 717-730.
Diem, J. E. 2006. Synoptic-Scale Controls of Summer Precipitation in the Southeastern United States. Journal of climate, 19: 613-621, DOI: 10.1175/JCLI3645.1. [DOI:10.1175/JCLI3645.1]
https://doi.org/10.1175/1520-0450(1987)0262.0.CO;2 [DOI:10.1175/1520-0450(1987)0262.0.CO;2]
Vicente-Serrano, S. M.; J. I. Lopez-Moreno. 2006. The influence of atmospheric circulation at different spatial scales on winter drought variability through a semi-arid climatic gradient in northeast Spain. International journal of climatology, 26: 1427-1453, DOI: 10.1002/joc.1387. [DOI:10.1002/joc.1387]
Sheridan, S. C. 2002. The redevelopment of a weather-type classification scheme for North America. International journal of climatology, 22: 51-68. DOI: 10.1002/joc.709.
Pfister, C.; R. Weingartner, and J. Luterbacher. 2006. Hydrological winter droughts over the last 450 years in the Upper Rhine basin: a methodological approach. Hydrological Sciences Journal, 51(5): 966-985, ISSN: 2150-3435, http://dx.doi.org/10.1623/hysj.51.5.966. [DOI:10.1623/hysj.51.5.966]
Bhalme, H. N.; D. A. Mooley. 1980. Large-scale drought/floods and monsoon circulation. Monthly weather review. 108: 1197-1211.
Santos, J.; J. Corte-real, and S. Leite. 2007. Atmospheric large-scale dynamics during the 2004/2005 winter drought in Portugal. International journal of climatology, 27: 571-586, DOI: 10.1002/joc.1425. [DOI:10.1002/joc.1425]
https://doi.org/10.1175/1520-0493(1980)1082.0.CO;2 [DOI:10.1175/1520-0493(1980)1082.0.CO;2]
Verdon-Kidd, D. C.; A. S. Kiem. 2009. Nature and causes of protracted droughts in southeast Australia: Comparison between the Federation, WWII, and Big Dry droughts. Geophysical research letters, 36: 1-6, Doi: 10.1029/2009GL041067. [DOI:10.1029/2009GL041067]
Pena, M.; M. W. Douglas. 1998. Characteristics of Wet and Dry Spells over the Pacific Side of Central America during the Rainy Season. Monthly weather review, 130: 3054-3073.
Charabi, Y.; S. Al-Hatrushi. 2010. Synoptic aspects of winter rainfall variability in Oman. Atmospheric Research, 95: 470-486. [DOI:10.1016/j.atmosres.2009.11.009]
https://doi.org/10.1175/1520-0493(2002)1302.0.CO;2 [DOI:10.1175/1520-0493(2002)1302.0.CO;2]
Wang, S. Y.; J. H. Yoon, R. R. Gillies, and C. Cho. 2013. What Caused the Winter Drought in Western Nepal during Recent Years? Journal of climate, 26: 8241-8256, DOI: 10.1175/JCLI-D-12-00800.1. [DOI:10.1175/JCLI-D-12-00800.1]
Mo, K. C.; J. N. Paegle, and R. W. Higgins. 2001. Atmospheric Processes Associated with Summer Floods and Droughts in the Central United States. Journal of climate, 10: 3028-3046.
Miron, O.; P. D. Tyson. 1984. Wet and dry conditions and pressure anomaly fields over South Africa and the adjacent oceans, 1963-79. Monthly weather review, 112: 2127-2132.
https://doi.org/10.1175/1520-0493(1984)1122.0.CO;2 [DOI:10.1175/1520-0493(1984)1122.0.CO;2]
https://doi.org/10.1175/1520-0442(1997)0102.0.CO;2 [DOI:10.1175/1520-0442(1997)0102.0.CO;2]
Shabbar, A.; B. R. Bonsal, and K. Szeto. 2011. Atmospheric and Oceanic Variability Associated with Growing Season Droughts and Pluvials on the Canadian Prairies. Atmosphere-Ocean, 49 (4): 339-355, ISSN: 1480-9214, http://dx.doi.org/10.1080/07055900.2011.564908. [DOI:10.1080/07055900.2011.564908]
Diem, J. E. 2006. Synoptic-Scale Controls of Summer Precipitation in the Southeastern United States. Journal of climate, 19: 613-621, DOI: 10.1175/JCLI3645.1.
Rimkus, E.; J. Kazys, D. Valiukas, and G. Stankunavicius. 2014. The atmospheric circulation patterns during dry periods in Lithuania. Oceanologia, 56 (2): 223-239, doi:10.5697/oc.56-2.223. [DOI:10.5697/oc.56-2.223]
Vicente-Serrano, S. M.; J. I. Lopez-Moreno. 2006. The influence of atmospheric circulation at different spatial scales on winter drought variability through a semi-arid climatic gradient in northeast Spain. International journal of climatology, 26: 1427-1453, DOI: 10.1002/joc.1387.
Omidvar, K.; M. Fatemi, M. Narangifard, and K. B. B. Hatami. 2016. A Study of the Circulation Patterns Affecting Drought and Wet Years in Central Iran. Advances in Meteorology, 2016: 1-14, http://dx.doi.org/10.1155/2016/1843659. [DOI:10.1155/2016/1843659]
Pfister, C.; R. Weingartner, and J. Luterbacher. 2006. Hydrological winter droughts over the last 450 years in the Upper Rhine basin: a methodological approach. Hydrological Sciences Journal, 51(5): 966-985, ISSN: 2150-3435, http://dx.doi.org/10.1623/hysj.51.5.966.
Sen, Z.; 2010. Fuzzy Logic and Hydrological Modeling. Taylor and Francis Group, CRC Press, New York, PP: 340. [DOI:10.1201/9781439809402]
Santos, J.; J. Corte-real, and S. Leite. 2007. Atmospheric large-scale dynamics during the 2004/2005 winter drought in Portugal. International journal of climatology, 27: 571-586, DOI: 10.1002/joc.1425.
Verdon-Kidd, D. C.; A. S. Kiem. 2009. Nature and causes of protracted droughts in southeast Australia: Comparison between the Federation, WWII, and Big Dry droughts. Geophysical research letters, 36: 1-6, Doi: 10.1029/2009GL041067.
Charabi, Y.; S. Al-Hatrushi. 2010. Synoptic aspects of winter rainfall variability in Oman. Atmospheric Research, 95: 470-486.
Wang, S. Y.; J. H. Yoon, R. R. Gillies, and C. Cho. 2013. What Caused the Winter Drought in Western Nepal during Recent Years? Journal of climate, 26: 8241-8256, DOI: 10.1175/JCLI-D-12-00800.1.
Miron, O.; P. D. Tyson. 1984. Wet and dry conditions and pressure anomaly fields over South Africa and the adjacent oceans, 1963-79. Monthly weather review, 112: 2127-2132.
https://doi.org/10.1175/1520-0493(1984)1122.0.CO;2 [DOI:10.1175/1520-0493(1984)1122.0.CO;2]
Shabbar, A.; B. R. Bonsal, and K. Szeto. 2011. Atmospheric and Oceanic Variability Associated with Growing Season Droughts and Pluvials on the Canadian Prairies. Atmosphere-Ocean, 49 (4): 339-355, ISSN: 1480-9214, http://dx.doi.org/10.1080/07055900.2011.564908.
Rimkus, E.; J. Kazys, D. Valiukas, and G. Stankunavicius. 2014. The atmospheric circulation patterns during dry periods in Lithuania. Oceanologia, 56 (2): 223-239, doi:10.5697/oc.56-2.223.
Omidvar, K.; M. Fatemi, M. Narangifard, and K. B. B. Hatami. 2016. A Study of the Circulation Patterns Affecting Drought and Wet Years in Central Iran. Advances in Meteorology, 2016: 1-14, http://dx.doi.org/10.1155/2016/1843659.
Sen, Z.; 2010. Fuzzy Logic and Hydrological Modeling. Taylor and Francis Group, CRC Press, New York, PP: 340.