مجله ژئوفیزیک ایران

مجله ژئوفیزیک ایران

تاثیر گرمایش سریع شمالگان بر الگوهای جوّی در غرب آسیا

نوع مقاله : مقاله پژوهشی‌

نویسندگان
1 دانشجوی دکتری هواشناسی، موسسه ژئوفیزیک دانشگاه تهران، ایران
2 دانشیار گروه فیزیک فضا، موسسه ژئوفیزیک دانشگاه تهران، ایران
چکیده
آهنگ افزایش دمای نامتناسب شمالگان نسبت به میانگین جهانی گرمایش سریع شمالگان نامیده می‌شود. با کاهش‌ شیو نصف‌النّهاری‌ دما،‌ چینش قائم سرعت‌ باد مداری و در نتیجه سرعت باد در ترازهای‌ بالا نیز کاهش‌ می‌یابد. به‌ دنبال کاهش‌ سرعت‌ باد مداری‌، امواج راسبی‌ بزرگ‌مقیاس با سرعت‌ کمتر از غرب به‌ شرق حرکت‌ می‌کنند و در پی‌ آن دامنه‌ این امواج افزایش‌ می‌یابد. هدف پژوهش حاضر بررسی تاثیر گرمایش سریع شمالگان در منطقه غرب آسیا واقع در 60-30 درجه شمالی و 75-20 درجه شرقی است. در این پژوهش دوره‌های پیش و پس ازگرمایش سریع شمالگان به ترتیب 1991-1965 و 2021-1995 درنظر گرفته شده است. محل تشکیل بیشینه دامنه امواج تراز میانی جو در فصل زمستان در دوره پس از گرمایش سریع شمالگان نسبت به دوره پیش از گرمایش سریع شمالگان، افزایشِ ارتفاع داشته است. همچنین گسترش عرض‌جغرافیایی بیشینه دامنه امواج راسبی در دوره پس از گرمایش سریع شمالگان کاهش یافته است. از تغییرات در محلِ تشکیل و پهنای گسترش امواج راسبی می‌توان نتیجه گرفت که علاوه بر تغییر محل فعالیت موج، سرعت انتشار شرق‌سوی امواج در این فصل بیشتر شده است. در فصل تابستان، در دوره مورد مطالعه تندی جت جنب‌حارّه بویژه در بخش‌های غربی تضعیف شده و موقعیت آن به سمت استوا جابجا شده است. شاخص گردش نصف‌النّهاری در دوره پس از گرمایش سریع شمالگان در اغلب بخش‌های غرب آسیا مقادیر معنادار مثبت و منفی دارد که به معنی نصف‌النّهاری شدن امواج تراز میانی جو است. حرکت کند‌ترِ الگوهای جوّی و افزایش احتمال وقوع رویدادهای فرین در تابستان در دوره پس از گرمایش سریع شمالگان قابل انتظار است. در فصل پاییز در دوره پس از گرمایش سریع شمالگان، موقعیت جت جنب‌حارّه، استواسو شده و شدّت آن، به ویژه در بخش شرقی منطقه غرب آسیا بیشتر شده است. تشدید جریان‌جتی در این بخش باعث تضعیف امواج سیّا‌ره‌ای شبه‌ساکن می‌شود.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

The impact of rapid Arctic warming on weather patterns in West Asia

نویسندگان English

Azam Sanei 1
Omid Alizadeh 2
Farhang Ahmadi-Givi 2
Parviz Iran Nejad 2
1 Ph.D. Student, Space Physics Department, Institute of Geophysics, University of Tehran, Tehran, Iran, Tehran, Iran
2 Associate Professor, Space Physics Department, Institute of Geophysics, University of Tehran, Tehran, Iran
چکیده English

The near-surface temperature in the Arctic has increased about four times greater than the global average temperature in recent decades, the feature called rapid Arctic warming or Arctic amplification. Different dynamical pathways have been hypothesized through which Arctic amplification may influence the midlatitude weather. There is also some evidence that extreme weather in midlatitudes of the Northern Hemisphere is linked to rapid Arctic warming.

We analyzed the ERA5 data for the period 1965–2021 to investigate the impact of rapid Arctic warming on weather patterns in West Asia. We defined pre-Arctic and post-Arctic amplification periods as 1965–1991 and 1995–2021, respectively. We analyzed wind speeds between 400 and 100 hPa to investigate the response of the upper-tropospheric jet stream in West Asia to rapid Arctic warming. We defined the meridional extent of an isopleth of the geopotential height at 500 hPa (Z500) as the difference between the maximum and minimum latitudes reached by a single Z500 isopleth each day. By averaging these daily values in different seasons during the pre-Arctic and post-Arctic amplification periods, we obtained seasonal averages of the meridional wave extent in these two time periods.

In winter, the altitude of the maximum geopotential height in the middle troposphere has increased in the post-Arctic amplification period. Moreover, the latitudinal extension of the maximum amplitude of Rossby waves has decreased. These two changes imply that the speed of the eastward propagation of Rossby waves has intensified in the post-Arctic amplification period.

In summer, the subtropical jet stream has wakened and shifted toward the equator in the post-Arctic amplification period. Due to the weakening of the meridional temperature gradient, both the subtropical and subpolar jet streams become weaker and shift poleward in summer. The poleward shift of the subtropical jet stream has also occurred in the post-Arctic amplification period, while the jet has weakened compared to the pre-Arctic amplification period. The analysis of the meridional circulation index (MCI) shows significant positive and negative values in most parts of West Asia in the post-Arctic amplification period, implying that Rossby waves have become wavier and their speed has decreased, associated with which is a higher possibility for the occurrence of extreme weather events in summer.

In autumn, in the post-Arctic amplification period, the jet stream has intensified in the eastern parts of West Asia compared to the climatology and the pre-Arctic amplification period. Between 50 and 75 ºE, the subtropical jet stream in West Asia has shifted toward the equator in the post-Arctic amplification period. As the subtropical jet stream separates the warmer tropical air from the colder air of higher latitudes, its equatorward shift in the post-Arctic amplification period implies the development of negative temperature anomalies in most parts of West Asia.

کلیدواژه‌ها English

rapid Arctic warming
West
Asia
geopotential height
jet stream
Rossby wave
Alizadeh, O., and Ghafarian, P., 2023, Large-scale driving mechanisms of the lowest and highest annual temperatures in northwestern Iran: Weather, doi: 10.1002/wea.4422 (in press).
Alizadeh, O., and Lin, Z., 2021, Rapid Arctic warming and its link to the waviness and strength of the westerly jet stream over West Asia: Global and Planetary Change, 199, 103447.
Barnes, E. A., 2013, Revisiting the evidence linking Arctic amplification to extreme weather in midlatitudes: Geophysical Research Letters, 40(17), 4734-4739.
 
Black, E., Blackburn, M., Harrison, G., Hoskins, B., and Methven, J., 2004, Factors contributing to the summer 2003 European heatwave: Weather, 59(8), 217-223.
Blackport, R., Screen, J. A., van der Wiel, K., and Bintanja, R., 2019, Minimal influence of reduced Arctic sea ice on coincident cold winters in mid-latitudes: Nature Climate Change, 9(9), 697-704.
Cavalieri, D. J., and Parkinson, C. L., 2012, Arctic sea ice variability and trends, 1979–2010: The Cryosphere, 6(4), 881-889.
Cohen, J., Screen, J. A., Furtado, J. C., et al., 2014, Recent Arctic amplification and extreme mid-latitude weather: Nature Geoscience, 7(9), 627-637.
Ding, Q., Wallace, J. M., Battisti, D. S., Steig, E. J., Gallant, A. J., Kim, H. J., and Geng, L., 2014, Tropical forcing of the recent rapid Arctic warming in northeastern Canada and Greenland: Nature, 509(7499), 209-212.
Farley Nicholls, J., and Toumi, R., 2014, On the lake effects of the Caspian Sea: Quarterly Journal of the Royal Meteorological Society, 140(681), 1399-1408.
Francis, J. A., and Hunter, E., 2006, New insight into the disappearing Arctic sea ice: Eos, Transactions American Geophysical Union, 87(46), 509-511.
Francis, J., and Skific, N., 2015, Evidence linking rapid Arctic warming to mid-latitude weather patterns: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 373(2045), 20140170.
Francis, J. A., and Vavrus, S. J., 2012, Evidence linking Arctic amplification to extreme weather in mid-latitudes: Geophysical Research Letters, 39(6).
Francis, J. A., and Vavrus, S. J., 2015, Evidence for a wavier jet stream in response to rapid Arctic warming: Environmental Research Letters, 10(1), 014005.
Gong, T., Feldstein, S., and Lee, S., 2017, The role of downward infrared radiation in the recent Arctic winter warming trend: Journal of Climate, 30(13), 4937-4949.
Hanna, E., Hall, R. J., and Overland, J. E., 2017, Can Arctic warming influence UK extreme weather?: Weather, 72(11), 346-352.
Hersbach, H., Bell, B., Berrisford, P., et al., 2020, The ERA5 global reanalysis: Quarterly Journal of the Royal Meteorological Society, 146(730), 1999-2049.
Holton, G., and Hakim, J., 2013, An Introduction to Dynamic Meteorology (Fifth Edition): Academic Press, 127-170, ISBN 9780123848666.
Honda, M., Inoue, J., and Yamane, S., 2009, Influence of low Arctic sea-ice minima on anomalously cold Eurasian winters: Geophysical Research Letters, 36(8).
Horton, D. E., Johnson, N. C., Singh, D., Swain, D. L., Rajaratnam, B., and Diffenbaugh, N. S., 2015, Contribution of changes in atmospheric circulation patterns to extreme temperature trends: Nature, 522(7557), 465-469.
Hoshi, K., Ukita, J., Honda, M., Nakamura, T., Yamazaki, K., Miyoshi, Y., and Jaiser, R., 2019, Weak stratospheric polar vortex events modulated by the Arctic sea-ice loss: Journal of Geophysical Research: Atmospheres, 124(2), 858-869.
Kim, B. M., Son, S. W., Min, S. K., et al., 2014, Weakening of the stratospheric polar vortex by Arctic sea-ice loss: Nature Communications, 5, 4646.
Koriche, S. A., Nandini-Weiss, S. D., Prange, M., et al., 2021, Impacts of variations in Caspian Sea surface area on catchment-scale and large-scale climate: Journal of Geophysical Research: Atmospheres, 126(18), e2020JD034251.
Laliberté, F., and Kushner, P. J., 2014, Midlatitude moisture contribution to recent Arctic tropospheric summertime variability: Journal of Climate, 27(15), 5693-5707.
Lee, S., Gong, T., Johnson, N., Feldstein, S. B., and Pollard, D., 2011, On the possible link between tropical convection and the Northern Hemisphere Arctic surface air temperature change between 1958 and 2001: Journal of Climate, 24(16), 4350-4367.
Luo, B., Luo, D., Wu, L., Zhong, L., and Simmonds, I., 2017, Atmospheric circulation patterns which promote winter Arctic Sea ice decline: Environmental Research Letters, 12(5), 054017.
Orsolini, Y. J., Senan, R., Benestad, R. E., and Melsom, A., 2012, Autumn atmospheric response to the 2007 low Arctic Sea ice extent in coupled ocean–atmosphere hindcasts: Climate Dynamics, 38(11), 2437-2448.
Overland, J., Francis, J. A., Hall, R., Hanna, E., Kim, S. J., and Vihma, T., 2015, The melting Arctic and midlatitude weather patterns: Are they connected? Journal of Climate, 28(20), 7917-7932.
Overland, J. E., and Wang, M., 2010, Large-scale atmospheric circulation changes are associated with the recent loss of Arctic Sea ice: Tellus A: Dynamic Meteorology and Oceanography, 62(1), 1-9.
Rantanen, M., Karpechko, A. Y., Lipponen, A., et al., 2022, The Arctic has warmed nearly four times faster than the globe since 1979: Communications Earth & Environment, 3(1), 168.
Schweiger, A. J., Lindsay, R. W., Vavrus, S., and Francis, J. A., 2008, Relationships between Arctic sea ice and clouds during autumn: Journal of Climate, 21(18), 4799-4810.
Screen, J. A., Deser, C., and Simmonds, I., 2012, Local and remote controls on observed Arctic warming: Geophysical Research Letters, 39(10).
Screen, J. A., and Simmonds, I., 2010, The central role of diminishing sea ice in recent Arctic temperature amplification: Nature, 464(7293), 1334-1337.
Screen, J. A., and Simmonds, I., 2013, Exploring links between Arctic amplification and mid-latitude weather: Geophysical Research Letters, 40(5), 959-964.
Stuecker, M. F., Bitz, C. M., Armour, K. C., et al., 2018, Polar amplification dominated by local forcing and feedbacks: Nature Climate Change, 8(12), 1076-1081.
Thompson, D. W., and Wallace, J. M., 2001, Regional climate impacts of the Northern Hemisphere annular mode: Science, 293(5527), 85-89.
Woollings, T., Barriopedro, D., Methven, J., et al., 2018, Blocking and its response to climate change: Current Climate Change Reports, 4(3), 287-300.
Yao, Y., Luo, D., Dai, A., and Simmonds, I., 2017, Increased quasi stationarity and persistence of winter Ural blocking and Eurasian extreme cold events in response to Arctic warming, Part I: Insights from observational analyses: Journal of Climate, 30(10), 3549-3568.
Zhang, X., He, J., Zhang, J., Polyakov, I., Gerdes, R., Inoue, J., and Wu, P., 2013, Enhanced poleward moisture transport and amplified northern high-latitude wetting trend: Nature Climate Change, 3(1), 47-51.
Zhang, X., Sorteberg, A., Zhang, J., Gerdes, R., and Comiso, J. C., 2008, Recent radical shifts of atmospheric circulations and rapid changes in Arctic climate system: Geophysical Research Letters, 35(22).
Zhang, P., Wu, Y., Simpson, I. R., Smith, K. L., Zhang, X., De, B., and Callaghan, P., 2018, A stratospheric pathway linking a colder Siberia to Barents-Kara Sea sea ice loss: Science Advances, 4(7), eaat6025.
Zhao, L., Lee, X., Smith, R. B., and Oleson, K., 2014, Strong contributions of local background climate to urban heat islands: Nature, 511(7508), 216-219.
Zhou, B., Xu, Y., Wu, J., Dong, S., and Shi, Y., 2016, Changes in temperature and precipitation extreme indices over China: Analysis of a high-resolution grid dataset: International Journal of Climatology, 36(3), 1051-1066.