ارتباط نوسان شمالگان(AO) با تغییرپذیری دمای زمستانه شمال غرب ایران

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشیار، گروه جغرافیا، دانشگاه پیام نور، تهران، ایران

2 استادیار، گروه جغرافیا، دانشگاه لرستان، خرم آباد، ایران

3 دانشجوی کارشناسی ارشد آب و هواشناسی، دانشگاه پیام نور، تهران، ایران

چکیده

نوسانات شمالگان (AO) یکی از الگوهای مؤثر تغییرپذیری گردش عمومی جو در منطقه برون حاره نیمکره شمالی و از عوامل اصلی کنترل عناصر اقلیمی مانند دما و بارش است. در این پژوهش به بررسی تأثیر فازهای مثبت و منفی این نوسان بر دمای زمستانه شمال غرب کشور، طی دوره آماری 2010-1965 پرداخته شد. به‌منظور دستیابی به اهداف این پژوهش از دو پایگاه داده: 1- داده دمای متوسط ایستگاه‌های همدید شمال غرب کشور و 2- داده‌های جوی شامل متغیر فشار تراز دریا(هکتوپاسکال) و ارتفاع ژئوپتانسیل(متر) استفاده شد. داده‌های جوی از مرکز ملی پیش‌بینی محیطی امریکا (NCEP/NCAR) دریافت شد. به‌منظور بررسی این داده‌ها محدوده‌ای‌ بین 40 - تا 120 درجه شرقی و 0 تا 80 درجه شمالی در نظر گرفته شد. سپس با استفاده از تحلیل خوشه‌ای‌ و ادغام وارد به تحلیل همدید فازها پرداخته شد. یک تقسیم‌بندی سه گروهه برای فاز منفی و تقسیم‌بندی سه گروهه دیگری برای فاز مثبت حاصل شد. برای هرکدام از گروه‌ها یک ماه نماینده تعیین شد. بعداز تحلیل الگوهای فشار به استخراج الگوهای مربوط به این فازها پرداخته شد درنهایت با استفاده از روش همبستگی به بررسی رابطه‌ی نمایه نوسان شمالگان با دمای زمستانه شمال غرب اقدام گردید. نتایج حاصله بیانگر این مطلب بود که میزان دما برای گروه‌هایی با فاز منفی نسبت به فاز مثبت دارای شرایط دمایی پایین تری بوده است. حال‌آنکه طی فاز مثبت این شرایط دمایی افزایش‌یافته است. با توجه به استقرار الگوهای فشار طی فاز منفی و میانگین دمای ماهیانه می توان چنین استنباط نمود که در این فاز شرایط سردتر و پایدارتری نسبت به فاز مثبت در محدوده مطالعاتی حاکم بوده است و به تبع آن در فاز مثبت شرایط دمایی بالاتری نسبت به فاز منفی رخ داده است. بررسی رابطه این نمایه با دمای زمستانه شمال غرب نشان از ضریب همبستگی معکوس و منفی دما با نوسان شمالگان دارد.

کلیدواژه‌ها


عنوان مقاله [English]

Relationship of Arctic Oscillation (AO) and winter temperatures variability on the north- west Iran

نویسندگان [English]

  • Amirhossein Halabian 1
  • Mostafa Karampour 2
  • Fariba Mahmoodimehr 3
1 Associate professor, Payame Noor University
2 Assistant Prof. Geography Department, Lorestan University, Khoramabad, Iran.
3 Msc in climatology, Payame Noor University
چکیده [English]

Abstract:

Introduction

Teleconnection patterns indicates a large variations that happen in the patterns of atmospheric waves and jet streams. Teleconnections are associated with the anomaly of atmospheric large scale and hemisphere circulation. Teleconnection patterns affecting on the amounts of temperature, precipitation, location and intensity of jet streams in the extensive regions. Arctic Oscillation is the leading mode of extratropical circulation from the surface to the lower-level stratosphere in the northern hemisphere(Hojati & Masoodian, 2018). Arctic Oscillation as one of the teleconnection patterns of the north hemisphere includes an atmospheric pressure anomaly in sea level in the north polar latitudes and middle latitude (45oN); that is shown in negative and positive phases(khosravi et al, 2007). Fluctuations in the Arctic Oscillation create a seesaw pattern in which atmospheric pressure at polar and middle latitudes fluctuates between negative and positive phases(Hojati& Masoodian, 2018). The AO pattern controls pressure, temperature and precipitation changes patterns and geopotential level, wind azimuth, in specific periods of year. Arctic Oscillation(AO) is one of the effective patterns in general circulation of atmosphere variability in extra-tropic region of northern hemisphere and is the main factors in controlling climate elements such as temperature and precipitation. Meanwhile temperature is one of climatic impressible element of the other climatic affective elements which is under the effect of this pattern (khosravi et al, 2007). Since temperature is a main element in the formation of the climate, and its variations can alter the climate structure of each region, therefore, studying the relationship of teleconnection patterns and temperature variability has a large part to be climatological research. In this regard, numerous researches has been carried out on the relationship of Arctic Oscillation (AO) and temperature changes, and the identification and analysis of the patterns of temperature has been considered by different methods in numerous studies. Here, we can be mention researchers such as Thompson and Wallace(1998), Wallace(2000), Thompson(2000), Cintia(2000), Roger et al(2000), Gong et al(2002), Philip et al(2002), Gong and Wang(2003), Daoyi and Shaou(2003), Wang et al(2005), Bond and Harrison(2006), Turkes and Erlat(2008), Sun and Ahn(2014) and in Iran, Masoodian(2005), Nazemalsadat et al(2006), Khosaravi et al(2007), Nasr isfahani et al(2008), Khoshakhlagh et al(2008), Esfandiari et al(2009), Khorshiddost et al(2010) and Alizadeh et al(2011). Since the identification of temperature patterns and its variations is very important for management and planning, this research seeks to evaluate and analyze the relationship of Arctic Oscillation (AO) and winter temperature variability on the north- west Iran.

Materials and methods

In this research we examined the effect of this oscillation positive and negative phases on north-west winter temperature of country during 1965-2010. To achieve this goals, two databases was used. First, the mean temperature data of north-west synoptic stations of country and second, atmospheric data including sea level peressure variable ( hPa) and geopotential height(m). Atmospheric data were recieved from NCEP/NCAR. To study these data, a framework has been considered between -40-120 degree eastern and 0 - 80 degree northern with resolution of 2.5*2.5 degree that have been borrowed from database of (NCEP/NCAR) dependent to National Atmosphere and Oceanography Institute of USA. Then, agglomerative hierarchical cluster analysis on the basis of ward linkage method have been done on data of negative and positive phases in Matlab software. A three groups classification has been obtained for negative phase and the other 3 groups classification for positive phase. Each group was assigned to an exponent month. After analyzing the patterns, we educed the patterns related to these phases. Finally, we studied the relationship between Arctic Oscillation exponent and north- west winter temperature by using correlation method. All of these steps and calculations conducted by using Matlab, GrADS and Surfer.

Results and discussion

Obtained results represented that the temperature value in negative phase groups was lower than positive phases. Whereas this temperature condition was increased during positive phases. According to pressure patterns deployment during negative phase and monthly temperature average, we can deduce that in this phase, the cooler and more stable conditions have prevailed in studied region than positive phase and consequently, the higher temperature condition has been accurred in positive phase than negative phase.

Conclusion

Studying the relationship of the exponent with winter temperature in north-west indicate the inverse and negative correlation coeficient with Arctic Oscillation.

کلیدواژه‌ها [English]

  • Synoptic Analysis
  • Temperature
  • Arctic oscillation
  • phase
  • Iran
  1. Esfandiari, F., Sobhani, B., Azadi Mobaraki, M. & Jafaezadeh, F. (2009). A statistical analysis of snowy days in Tabriz and their association with the phenomenon of large-scale ocean/ atmosphere irculation of the Atlantic Ocean (NAO). Journal of geographical sciences, 10(13), 84-102.
  2. Esmaili, K., Gandomkar, A., & Khodagholi, M. (2020). Identifying the trend of temperature changes in the South Iranian coasts and its relationship with teleconnection. Physical Geography Quarterly, 13(49), 1-22.
  3. Akbari T.,& Masoodian S.A. (2007). An analysis of relationship between monthly temperature of Iran and teleconnection patterns of Northern hemisphere.  Research Bulletin of Isfahan University (Humanities), 22(1), 117-132.
  4. Halabian, A., & Mohammadi, B. (2012). The relation of monthly temperature of some sample stations in Iran with different Enso indices. Geographic Space, 12(38), 1-19.
  5. Khosravi M.,Karimi Khajeh Lengi, S., & Saligheh M. (2007). The relationship between Arctic Oscillation index and temperature variabilities in shahr-e-kord station. Geography and Development, 5(9), 126-136.
  6. Khourshiddoust A.M., Ghavidel Rahimi, Y., & Abbaszadeh, K. (2010). The application of large-scale atmospheric-oceanic patterns in the analysis of precipitation fluctuations (case study of Ahar station). Geographic Space, 10(29), 95-128.
  7. Khoush Akhlagh, F., Ghanbari, N., & Masoumpour Samakoush, J. ( 2009). The study of North Atlantic Oscillation effect on temperature and precipitation regimes of Southern shores of Caspian Sea. Physical Geography Research, 66, 57-70.
  8. Ghavidel Rahimi, Y., Farajzadehasl M., & Hatamikia, M. (2016). The Artic Oscillation (AO) and its role on of winter time monthly minimum temperatures variability in Northeastern region of Iran. Journal of Geographical Sciences, 16(42), 41-58.
  9. Asakereh, H., (2007). Climate Change. Zanjan University, Iran, 256 pages.
  10. Alijani, B. & Kaviani, M.R. (2011). Principle of Climatatology. Samt, Tehran, Iran, 592 pages.
  11. Alizadeh, A., Erfanian M., & Ansari, H. (2011). Assessment of teleconnection patterns affecting rainfall and temperature (case study: Mashhad synoptic station). Iranian Journal of Irrigation and Drainage, 5(2), 176-185.
  12. Qayour, H.A., & Asakereh, H. (2012). Study of teleconnection effect on Iran climate (case study: the effect of North Atlantic fluctuations and Southern fluctuations on the average monthly changes in Jask temperature). Geographical Researches, 16-17(4-1), 94-113.
  13. Farshadfar, E. (2010). Multivariate principles and procedures of statistics. Taghbostan, Kermanshah, Iran, 754 pages.
  14. Gerkaninezhad Moshozi Z., & Bazrafshan, O. (2018). Impact of climatic signals on the wet and dry season precipitation (case study: Persian Gulf and Oman Sea watersheds). Journal of the Earth and Space Physics, 44(2), 333-349.
  15. Masoodian, S.A. (2005). The effect of ENSO on precipitation in Iran, Journal of Geography and Regional Development, 3(4), 73-82.
  16. Nazem Alsadat S.M.J., Rahimi M., & Keshavarzi, A.R. (2006). An evaluation of the impact of El Nino - Southern Oscillation (ENSO) on stream flow and hydrological drought (wet) in Fars province. Iranian Journal of Agricultural Sciences, 37(2), 361-369.
  17. Nasr Esfahani, M.A., Mohebolhojah, A.L. & Ahmadi Givi, F., (2009). The effects of NAO on some meteorological parameters over Middle East and South West Asia. Iranian Journal of Geophysics, 2(2), 51-64.
  18. Bond, N, A, & Harrisond, E, (2006). ENSO’S effect on Alaska during opposite phases of the Arctic Oscillation. Int J Climatol, 26, 1821–1841
  19. Cintia B. UVO, (2003). Analysis and regionalization of northern Atlantic European winter precipitation based on its relationship with the north Atlantic Oscillation. International Journal of Climatology, 23, 185- 1194.
  20. Daoyi‚G., & Shaou‚ W. (2003). Influence of Arctic Oscillation on winter climate over China. Journal of Geographical sicenec, 13(2), 208-21
  21. Gong, D. Y., Ho, C.H., (2002). The Siberian high and climate change over middle to high latitude Asia, Appl. Climatol., 72,1-9.
  22. Gong, D.Y., & Wang, S.W. (2003). Influence of Arctic Oscillation on winter climate over China, Journal of Geographical Sciences, 13, 208–216
  23. Mohammadrezaei, M., Soltani, S., & Modarres, R. (2020). Evaluating the effect of ocean-atmospheric indices on drought in Iran, Theoretical and Applied Climatology, 1-2, 219–230.
  24. Sun, J., & Ahn, J.B. (2014). Dynamical seasonal predictability of the Arctic Oscillation using a CGCM. International Journal of Climatology,35, 45-62
  25. Philip Nott, M., Desante, D. F., Siegel, R., & Pyle, P. (2002). Influences of the El Nino /Southern Oscillation and the North Atlantic Oscillation on Aviav productivity in forest of the pacific Nortewest of North America, Global Ecology and Biogeography, 11, 333-342.
  26. Rigor, G., Colony, R.L., & Martin, S. (2000). Variations in surface air temperature observations in the Arctic, J Climate,13,896–914.
  27. Thompson D.W. J., & Wallace, J. M. (2000) (b). Annular modes in the extratropical circulation, Part II: J. Climate, 13(5),1000- 1016.
  28. Thompson D.W. J., & Wallace, J. M. (2000) (a). Annular modes in the extratropical circulation, Part I: Month -to- Month variability. Climate, 13(5), 1000-1016.
  29. Turkes‚M., & Erlat‚ E. (2008). Influence of the Arctic Oscillation on the variability of winter mean temperatures in Turkey. Theoretical and applid climatology,92, 75-85.
  30. Wang‚ D.‚ Wang‚ C., Yang‚ X., & Lu‚ J. (2005). Winter Northern hemisphere surface air temperatre variability associated the Arctic Oscillation and North Atlantic Oscillation, Geophys, Res, lett‚ 32, 1-4.