Tsinkaye na Arctic
 Tsinkaye na Arctic | |
|---|---|
meteorological phenomenon (en)  |
Arctic oscillation (AO) ko Northern Annular Mode / Northern Hemisphere Annular Mode (NAM) wani yanayi ne a arewacin Arctic pole na digiri 55 latitude. Yana da muhimmiyar yanayin canjin yanayi ga Arewacin Hemisphere. Ana kiran analog din kudancin Antarctic oscillation ko Southern Annular Mode (SAM). Alamar ta bambanta a tsawon lokaci ba tare da wani lokaci ba, kuma ana nuna shi ta hanyar matsin lamba na matakin teku na lokaci guda na alamar daya a cikin Arctic, daidaita shi da anomalies na alamar da ke gaba da kusan 37-45 ° N.[1]
Oscillation na Arewacin Atlantic (NAO) dangi ne na kusa da oscillation na Arctic. Akwai muhawara game da ko ɗayan ko ɗayan ya fi wakiltar yanayin yanayi. Ana iya gano NAO a hanyar da ta fi dacewa da jiki, wanda zai iya haifar da ƙarin tasiri a kan tasirin canje-canje a cikin yanayi.
Bayyanawa
[gyara sashe | gyara masomin]
Oscillation na Arctic ya bayyana a matsayin mai kama da zobe (ko "annular") na matsin lamba na matakin teku wanda ke tsakiya a kan sanduna. Kasancewar nahiyoyi da manyan wuraren da ke ƙasa suna rushe tsarin da ke kama da zobe a gefen Arctic, yayin da anomalies da ke kewaye da gefen Antarctic kusan zagaye ne.
Masana ilimin yanayi sun yi imanin cewa yanayin Arctic oscillation yana da alaƙa da (kuma don haka yana da wani ɓangare na tsinkaya na) Yanayin yanayi na duniya. Masanin yanayin yanayi na NASA James E. Hansen ya bayyana tsarin da Arctic oscillation ke shafar yanayi a maki don haka [bayani da ake buƙata] nesa da Arctic, kamar haka (lura, duk da haka, cewa bayanin Hansen ba daidai ba ne: matsin lamba a cikin Arctic yana da ƙasa a cikin matakin AO mai kyau, wanda tsari kuma ke inganta jet stream):
The degree to which Arctic air penetrates into middle latitudes is related to the AO index, which is defined by surface atmospheric pressure patterns. When the AO index is positive, surface pressure is high in the polar region. This helps the middle latitude jet stream to blow strongly and consistently from west to east, thus keeping cold Arctic air locked in the polar region. When the AO index is negative, there tends to be low pressure in the polar region, weaker zonal winds, and greater movement of frigid polar air into middle latitudes."[3]
An bayyana alamar oscillation ta Arctic ta amfani da ƙarancin tsawo na yau da kullun ko na kowane wata 1000 hPa daga latitudes 20 ° N zuwa 90 ° N. Ana tsara ƙarancin a kan tsarin loading na oscillation na Arctic, [4] wanda aka bayyana a matsayin aikin orthogonal na farko (EOF) na kowane wata yana nufin 1000 hPa na tsawo a lokacin 1979-2000. Sa'an nan kuma ana daidaita jerin lokutan tare da daidaitattun daidaitattun ma'auni na kowane wata.
Lokaci-lokaci
[gyara sashe | gyara masomin]A cikin mafi yawan ƙarni da suka gabata, oscillation na Arctic ya canza tsakanin matakai masu kyau da mara kyau. Bayanai ta amfani da ma'anar tafiyar kwanaki 60 ya nuna oscillation yana ci gaba zuwa mafi kyawun lokaci tun daga 1970s, ko da yake ya yi tafiya zuwa mafi tsaka tsaki a cikin shekaru goma da suka gabata. Har ila yau jujjuyawar tana jujjuyawa tsakanin ma'auni mara kyau da tabbatacce akan ma'auni na yau da kullun, kowane wata, yanayi da ma'auni na shekara-shekara, kodayake masana yanayin yanayi sun sami babban matakan tsinkaya ga tsinkayar ɗan gajeren lokaci. Dangantaka tsakanin ainihin abubuwan lura da ma'anar kwanaki 7 na Tsarin Hasashen Duniya na Hasashen AO kusan 0.9. [5]
Edward Lorenz ne ya fara gano wannan yanayin a tsakanin matsin lamba na teku a cikin latitudes na polar da na matsakaici [6] kuma David WJ Thompson da John Michael Wallace ne suka sanya masa suna a shekarar 1998. [7]
Tasirin
[gyara sashe | gyara masomin]Cibiyar Bayanan Snow da Ice ta Kasa ta bayyana tasirin oscillation na Arctic a wasu daki-daki. A cikin kyakkyawan lokaci, matsin lamba mafi girma a tsakiya latitudes yana fitar da guguwar teku zuwa arewa, kuma canje-canje a cikin tsarin yaduwar suna kawo yanayin rigar zuwa Alaska, Scotland da Scandinavia, da kuma yanayin bushewa zuwa yammacin Amurka da Bahar Rum. A cikin kyakkyawan lokaci, iska mai sanyi na hunturu ba ya kaiwa zuwa tsakiyar Arewacin Amurka kamar yadda zai kasance a lokacin mummunan lokaci na oscillation. Wannan yana kiyaye yawancin Amurka a gabashin Dutsen Rocky da dumi fiye da yadda aka saba, amma ya bar Greenland da Newfoundland da sanyi fiye da yadda ya saba. Tsarin yanayi a cikin mummunan lokaci gabaɗaya "abanci" ne ga waɗanda ke cikin kyakkyawan lokaci.
Masana ilimin yanayi yanzu suna kiran sauye-sauyen Arctic a cikin bayanin jama'a na hukuma game da matsanancin yanayi.
Manazarta
[gyara sashe | gyara masomin]- ↑ "Arctic Oscillation (AO) time series, 1899 – June 2002". Archived from the original on 2013-05-18. Retrieved 2012-01-21.
- ↑ "CPC - Teleconnections: Arctic Oscillation Loading Pattern".
- ↑ Hansen, James; Reto Ruedy; Makiko Sato; Ken Lo (2009). "If It's That Warm, How Come It's So Damned Cold?" (PDF). Retrieved 2013-07-17. Cite journal requires
|journal=(help) - ↑ "CPC - Teleconnections: Arctic Oscillation Loading Pattern".
- ↑ "CPC – Monitoring & Data: Daily Arctic Oscillation Index". Archived from the original on 2010-12-30. Retrieved 2012-01-29.
- ↑ Lorenz, Edward N. (1951). "Seasonal and Irregular Variations of the Northern Hemisphere Sea-Level Pressure Profile". Journal of Meteorology. 8 (1): 52–59. Bibcode:1951JAtS....8...52L. doi:10.1175/1520-0469(1951)008<0052:SAIVOT>2.0.CO;2. ISSN 1520-0469.
- ↑ Thompson, David W. J.; John Michael Wallace (1998). "The Arctic oscillation signature in the wintertime geopotential height and temperature fields". Geophysical Research Letters. 25 (9): 1297–1300. Bibcode:1998GeoRL..25.1297T. doi:10.1029/98GL00950. Retrieved 2010-08-28.