Juyawar thermohaline
 Juyawar thermohaline | |
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| Bayanai | |
| Ƙaramin ɓangare na |
fluid flow (en)  |
| Class of object(s) of occurrence (en) |
sea water (en) |
Thermohaline wurare dabam dabam (THC) wani bangare ne na babban sikelin teku zagayawa da ake samu ta duniya yawa gradients samu ta hanyar zafi saman da kuma ruwa ruwa.[1][2]Sunan thermohaline ya samo asali ne daga thermo-, yana nufin zafin jiki, da kuma haline, yana nufin abun ciki na gishiri - abubuwan da ke ƙayyade yawan ruwan teku.
Ruwan saman da iska ke tuƙawa (kamar kogin Gulf) yana tafiya ne daga mashigin tekun Atlantika, sanyaya da nutsewa a kan hanyar zuwa manyan latitudes - daga ƙarshe ya zama wani ɓangare na Ruwa mai zurfi na Arewacin Atlantic - kafin ya kwarara cikin raƙuman teku.[3] Yayin da mafi yawan ruwan thermohaline ya tashi a cikin Tekun Kudancin, mafi tsufa ruwa (tare da lokacin wucewa na kimanin shekaru 1000) ya tashi a cikin Arewacin Pacific; [4] mai yawa cakude yana faruwa tsakanin raƙuman teku, yana rage bambanci a cikin girman su, samar da tekun duniya tsarin duniya.[3]. Ruwan da ke cikin waɗannan da'irori yana ɗaukar makamashi - a matsayin zafi - da kuma taro - kamar narkar da daskararru da iskar gas - a duk faɗin duniya. Saboda haka, yanayin yawo yana tasiri sosai ga yanayin duniya.
Sau da yawa ana kiran zagawar thermohaline a matsayin bel ɗin jigilar teku, babban mai jigilar teku, ko "bel ɗin jigilar kaya na duniya" - kalmar da masanin kimiyyar yanayi Wallace Smith Broecker ya yi.[5][6]. Hakanan an san shi azaman juyewar juyewar yanayi, ko MOC; Sunan da aka yi amfani da shi don nuna cewa yanayin wurare dabam dabam da ke haifar da yanayin zafin jiki da gishirin gishiri ba lallai ba ne wani ɓangare na zagayawa ɗaya na duniya. Wannan yana faruwa ne, a wani ɓangare, ga wahalar da ke tattare da keɓance sassan wurare dabam dabam na zazzaɓi da zafin jiki da gishiri ke haifarwa daga waɗanda abin ya shafa kamar iska da ƙarfi.[7]
Wannan zagayawa ta duniya ta ƙunshi manyan "gaɓoɓi" biyu; Atlantika medidional juye wurare dabam dabam (AMOC) a tsakiya a arewacin Tekun Atlantika, da Kudancin Tekun na juye wurare dabam dabam, ko Kudancin Tekun meridional wurare dabam dabam (SMOC) located kusa da Antarctica. Tun da kashi 90% na yawan mutane sun mamaye Arewacin Hemisphere, [8] an gudanar da bincike mai zurfi akan AMOC, duk da haka SMOC yana da mahimmanci daidai ga yanayin duniya. Shaidu sun nuna cewa sassan biyu suna raguwa saboda sauyin yanayi a cikin layi tare da karuwar adadin dilution daga narkewar zanen kankara - yana da matukar tasiri ga salinity na ruwa na Antarctic.[9][10] Bugu da kari, yuwuwar rugujewar ko wanne zagayowar zuwa wata kasa mai rauni yana misalta abubuwan da ke faruwa a tsarin yanayi. Idan ko wannen helkwata ya gamu da rugujewar zagawar sa, yiyuwar tsawaita busasshen ruwa da fari za su karu yayin da hazo ke raguwa, yayin da sauran helkwatar za su yi ruwa. Tsarin halittun ruwa yana iya samun ƙarancin abinci mai gina jiki da kuma samun ƙarancin iskar oxygen. A Arewacin Hemisphere, rugujewar AMOC zai haifar da ƙarancin yanayin zafi a yawancin ƙasashen Turai, yayin da ake hasashen gabar tekun gabas ta Arewacin Amurka za ta ga saurin hawan teku. An yarda da rugujewar waɗannan zagayawa gabaɗaya ya wuce fiye da ɗari ɗari, kuma yana iya faruwa ne kawai idan yanayin zafin teku ya yi sauri da girma. Koyaya, waɗannan tsinkaya suna da alamar rashin tabbas.[10][11]
Tarihin bincike
[gyara sashe | gyara masomin]An dade da sanin cewa iska na iya fitar da magudanan ruwa, amma a saman kasa kawai.[8] A cikin karni na 19, wasu masana kimiyyar teku sun ba da shawarar cewa jujjuyawar zafi na iya fitar da igiyoyi masu zurfi. A cikin 1908, Johan Sandström ya yi jerin gwaje-gwaje a wani tashar binciken ruwa ta Bornö wanda ya tabbatar da cewa magudanar ruwa ta hanyar canja wurin makamashin zafi na iya wanzuwa, amma yana buƙatar cewa "dumi yana faruwa a zurfin zurfi fiye da sanyaya".[1][9]. A al'ada, akasin haka yana faruwa, saboda ruwan teku yana dumama daga sama da Rana kuma ya zama ƙasa mai yawa, don haka saman saman yana shawagi a saman na'urar sanyaya, yadudduka masu yawa, wanda ke haifar da madaidaicin teku. Duk da haka, iska da igiyoyin ruwa suna haifar da cakuɗawa tsakanin waɗannan ruwan yadudduka, tare da haɗuwar diapycnal da igiyar ruwa ke haifarwa ta zama misali ɗaya.[10] Wannan hadawa shine abin da ke ba da damar haɗuwa tsakanin sassan teku, don haka, igiyoyin ruwa mai zurfi.[1]
A cikin 1920s, an faɗaɗa tsarin Sandström ta hanyar lissafin rawar salinity a cikin samuwar ruwan teku.[1] Salinity yana da mahimmanci saboda kamar zafin jiki, yana rinjayar yawan ruwa. Ruwa yana raguwa yayin da zafinsa ya karu kuma nisa tsakanin kwayoyin halittarsa yana fadada, amma yana da yawa yayin da gishiri ya karu, tun da akwai gishiri mai yawa da ke narkewa a cikin ruwan.[15]. Bugu da ari, yayin da ruwa mai kyau ya kasance mafi yawa a 4 ° C, ruwan teku kawai yana yin yawa yayin da yake sanyi, har sai ya kai ga daskarewa. Wannan wurin daskarewa kuma yana da ƙasa da na ruwa mai daɗi saboda gishiri, kuma yana iya zama ƙasa da -2 ° C, dangane da salinity da matsa lamba.[16]
Manazarta
[gyara sashe | gyara masomin]- ↑ 1.0 1.1 Rahmstorf, S (2003). "The concept of the thermohaline circulation" (PDF). Nature. 421 (6924): 699. Bibcode:2003Natur.421..699R. doi:10.1038/421699a. PMID 12610602. S2CID 4414604.
- ↑ Lappo, SS (1984). "On reason of the northward heat advection across the Equator in the South Pacific and Atlantic ocean". Study of Ocean and Atmosphere Interaction Processes. Moscow Department of Gidrometeoizdat (in Mandarin): 125–9.
- ↑ 3.0 3.1 "What is the global ocean conveyor belt?". NOAA. Archived from the original on 31 December 2017.
- ↑ Primeau, F (2005). "Characterizing transport between the surface mixed layer and the ocean interior with a forward and adjoint global ocean transport model" (PDF). Journal of Physical Oceanography. 35 (4): 545–64. Bibcode:2005JPO....35..545P. doi:10.1175/JPO2699.1. S2CID 130736022
- ↑ Schwartz, John (20 February 2019). "Wallace Broecker, 87, Dies; Sounded Early Warning on Climate Change". The New York Times. ISSN 0362-4331. Retrieved 5 June 2022.
- ↑ de Menocal, Peter (26 March 2019). "Wallace Smith Broecker (1931–2019)". Nature. 568 (7750): 34. Bibcode:2019Natur.568...34D. doi:10.1038/d41586-019-00993-2. S2CID 186242350.
- ↑ Wunsch, C (2002). "What is the thermohaline circulation?". Science. 298 (5596): 1179–81. doi:10.1126/science.1079329. PMID 12424356. S2CID 129518576.
- ↑ Schmidt, Gavin (26 May 2005). "Gulf Stream slowdown?". RealClimate. Archived from the original on 20 February 2006.
- ↑ Rahmstorf, S (2006). "Thermohaline Ocean Circulation" (PDF). In Elias, S. A. (ed.). Encyclopedia of Quaternary Sciences. Elsevier Science. ISBN 0-444-52747-8.
- ↑ Eden, Carsten (2012). Ocean Dynamics. Springer. pp. 177. ISBN 978-3-642-23449-1.