Tashoshin tashar kankara

tashar tashar kankara wani nau'in tashar ruwa mai narkewa ne wanda ke samuwa a ƙarƙashin tashar kan kankara mai iyo da aka haɗa da takalma na kankara. Tashoshin basal galibi ramuka ne masu zagaye waɗanda ke daidaitawa da kwararar kankara. Wadannan tashoshin ana samun su galibi a kusa da Greenland da kankara na Antarctic a wuraren da ke da ruwan teku mai dumi. Yammacin Antarctica musamman yana da mafi yawan tashoshin basal a duniya. Tashoshin basal na iya zama tsawon kilomita goma, faɗin kilomita, kuma ya yanke daruruwan mita zuwa cikin kankara. Wadannan tashoshin na iya canzawa kuma su girma daidai da sauri kamar yadda kankara ke iya, tare da wasu tashoshin da ke da ƙimar yankan da ke kusa da mita 22 a kowace shekara.  Ana rarraba tashoshin basal bisa ga abin da hanyoyin da suka kirkiresu da kuma inda suka samo asali.

Tashoshin basal na iya shafar farfajiyar kankara da yanayin basal. Manyan tashoshin basal tare da faɗin sama da kilomita 1 wanda ke yanke fiye da mita 50 a cikin kankara na kankara na iya samar da tashoshin farfajiyar da suka isa su gano ta hanyar tauraron dan adam.Alley, Karen E.; Scambos, Ted A.; Siegfried, Matthew R.; Fricker, Helen Amanda (April 2016). "Impacts of warm water on Antarctic ice shelf stability through basal channel formation". Nature Geoscience. 9 (4): 290–293. Bibcode:2016NatGe...9..290A. doi:10.1038/ngeo2675. ISSN 1752-0908. Tashoshin basal kuma suna samar da farfajiyar farfajiya da basal crevassing. Ta hanyar ƙirƙirar fasalulluka irin su basal da surface crevasses da kuma rage kankara shelves, basal tashoshin na iya lalata kankara shelf kuma ya ba da gudummawa ga asarar kankara.Dow, Christine F.; Lee, Won Sang; Greenbaum, Jamin S.; Greene, Chad A.; Blankenship, Donald D.; Poinar, Kristin; Forrest, Alexander L.; Young, Duncan A.; Zappa, Christopher J. (June 2018). "Basal channels drive active surface hydrology and transverse ice shelf fracture". Science Advances. 4 (6): eaao7212. Bibcode:2018SciA....4.7212D. doi:10.1126/sciadv.aao7212. ISSN 2375-2548. PMC 6007161. PMID 29928691.Alley, Karen E.; Scambos, Ted A.; Alley, Richard B. (March 2023). "The role of channelized basal melt in ice-shelf stability: recent progress and future priorities". Annals of Glaciology. 63 (87–89): 18–22. doi:10.1017/aog.2023.5. ISSN 0260-3055. S2CID 257753085.

 Matsayi 
Ana rarraba tashoshin basal zuwa manyan rukuni uku ta hanyar yadda kuma inda aka kafa su dangane da layin kafa na kankara: tashoshin da ke cikin teku, tashoshin subglacially, da tashoshin layin ƙasa.Alley, Karen E.; Scambos, Ted A.; Siegfried, Matthew R.; Fricker, Helen Amanda (April 2016). "Impacts of warm water on Antarctic ice shelf stability through basal channel formation". Nature Geoscience. 9 (4): 290–293. Bibcode:2016NatGe...9..290A. doi:10.1038/ngeo2675. ISSN 1752-0908. Layin da aka kafa shi ne ma'anar inda kankara ko kankara ya haɗu da teku kuma ya fara iyo, yana samar da kankara. Abubuwan da zasu iya zama tashoshin basal amma ba za a iya gano su ba tare da ƙarin bayani ba sun samar da rukuni na huɗu da aka sani da tashoshin yiwuwar.

 Tashoshin da ke cikin teku 
Tashoshin basal waɗanda ba su haɗu da layin ƙasa na kankara ba an san su da tashoshin teku. Duk da yake wasu tashoshin basal an kafa su ne daga ruwa mai narkewa daga takardar kankara, waɗannan tashoshin an cire su daga shimfidar kankara kuma dole ne a kafa su ta hanyar hanyoyin teku. Ruwa mai dumi na teku ya tashi zuwa tushe na kankara, ko saboda wani bump a cikin ƙasa ko kuma saboda yana da mafi girma, kuma yana narkewa da kasa na kankara.Vaughan, David G.; Corr, Hugh F. J.; Bindschadler, Robert A.; Dutrieux, Pierre; Gudmundsson, G. Hilmar; Jenkins, Adrian; Newman, Thomas; Vornberger, Patricia; Wingham, Duncan J. (September 2012). "Subglacial melt channels and fracture in the floating part of Pine Island Glacier, Antarctica: Subglacial Channels and Crevassing". Journal of Geophysical Research: Earth Surface. 117 (F3): n/a. doi:10.1029/2012JF002360. S2CID 131444235. Wannan ruwan dumi yawanci ana fitar da shi ta hanyar ruwan teku. Tashoshin da ke cikin teku sun zama masu zurfi daga asalin su a cikin hanyar kwarara (ƙanƙara). Alley, Karen E.; Scambos, Ted A.; Siegfried, Matthew R.; Fricker, Helen Amanda (April 2016). "Impacts of warm water on Antarctic ice shelf stability through basal channel formation". Nature Geoscience. 9 (4): 290–293. Bibcode:2016NatGe...9..290A. doi:10.1038/ngeo2675. ISSN 1752-0908.

 Tashoshin da ke ƙarƙashin dusar ƙanƙara 
Farkon tashar da ke karkashin glacially ya kasance kai tsaye a kan layin kafawa.Alley, Karen E.; Scambos, Ted A.; Siegfried, Matthew R.; Fricker, Helen Amanda (April 2016). "Impacts of warm water on Antarctic ice shelf stability through basal channel formation". Nature Geoscience. 9 (4): 290–293. Bibcode:2016NatGe...9..290A. doi:10.1038/ngeo2675. ISSN 1752-0908. Wadannan tashoshin an kafa su ne ta hanyar ruwan da ya narke a karkashin dusar ƙanƙara maimakon tsarin teku kawai kuma suna da alaƙa da su a kan kan kankara inda asarar taro ta hanyar narkewar subglacial ya wuce asarar daga jariri.Dow, Christine F.; Lee, Won Sang; Greenbaum, Jamin S.; Greene, Chad A.; Blankenship, Donald D.; Poinar, Kristin; Forrest, Alexander L.; Young, Duncan A.; Zappa, Christopher J. (June 2018). "Basal channels drive active surface hydrology and transverse ice shelf fracture". Science Advances. 4 (6): eaao7212. Bibcode:2018SciA....4.7212D. doi:10.1126/sciadv.aao7212. ISSN 2375-2548. PMC 6007161. PMID 29928691. Calving shine lokacin da kankara, kankara, ko kankara ya rasa taro ta hanyar kankara da ke fashewa cikin teku kuma yana samar da kankara. Tashoshin da ke karkashin glacially sun samo asali ne lokacin da ruwan da ya narke daga kankara ko kankara ya kai layin ƙasa kuma ya yi hulɗa da teku da ke kewaye. Ruwan da ya narke yana tashi, yana narke kankara da ke sama kuma yana samar da tashar. Ba kamar tashoshin da ke cikin teku ba, waɗannan tashoshin suna cikin zurfin su kai tsaye a layin ƙasa.

 Tashoshin da ke cikin layi 
Tashoshin da ke cikin layi suna kama da tashoshin da aka samo asali a cikin cewa suna tsallaka layin da ke cikin kankara. Wadannan tashoshin sun bambanta da cewa ba su samo asali ne daga ruwan da ya narke a karkashin glacial ba kuma a maimakon haka suna samuwa a wuraren da akwai yiwuwar kadan ko babu ruwan da ya rushe a karkashin glacier.Alley, Karen E.; Scambos, Ted A.; Siegfried, Matthew R.; Fricker, Helen Amanda (April 2016). "Impacts of warm water on Antarctic ice shelf stability through basal channel formation". Nature Geoscience. 9 (4): 290–293. Bibcode:2016NatGe...9..290A. doi:10.1038/ngeo2675. ISSN 1752-0908. Tashoshin da ke cikin ƙasa suna da halaye da yawa tare da tashoshin da aka samo asali daga teku. Dukansu an kafa su ne ta hanyar hanyoyin teku kuma suna zurfafawa.

 Rashin daidaituwa saboda tashoshin basal 

 Gidan kankara yana raguwa 
Lokacin da tashoshin basal suka shiga cikin kankara, suna samar da yanki, ingantaccen raguwa a wannan yankin. Lokacin da narkewar basal ke faruwa a kan kankara, saman shelf yana raguwa don rama canjin a cikin taro. Nazarin ya nuna cewa ƙarancin ƙididdiga tare da tashar basal na iya zama har zuwa sau uku matsakaicin ƙarancin kankara. Wadannan yankuna masu laushi sun fi rauni fiye da sauran kankara kuma sun fi fuskantar rashin kwanciyar hankali. Ruwan teku mai zafi wanda ya haifar da canjin yanayi an haɗa shi da karuwar tsarin tashar basal da kuma raguwar kankara.

 Rashin da ya faru 
Tashoshin basal na iya haifar da raguwa da raguwa, canza rarraba damuwa na kankara ta hanyar ƙirƙirar yankuna na tsawo da matsawa.Dow, Christine F.; Lee, Won Sang; Greenbaum, Jamin S.; Greene, Chad A.; Blankenship, Donald D.; Poinar, Kristin; Forrest, Alexander L.; Young, Duncan A.; Zappa, Christopher J. (June 2018). "Basal channels drive active surface hydrology and transverse ice shelf fracture". Science Advances. 4 (6): eaao7212. Bibcode:2018SciA....4.7212D. doi:10.1126/sciadv.aao7212. ISSN 2375-2548. PMC 6007161. PMID 29928691. Yankunan tsawo suna da matukar damuwa ga fashewar farfajiyar da basal. Kashewa yadda ya kamata yana haifar da tsagewa a cikin kankara wanda zai iya bambanta sosai a girman. Tashoshin basal suna samar da fashewar farfajiyar daidai da jagorancin kwararar kankara. Lokacin da ruwan da ya narke ya gudana cikin karyewa, mafi girman yawan ruwa idan aka kwatanta da kankara na iya ƙara girman tsagewa a cikin tsari da aka sani da hydrofracturing. Wannan na iya haifar da abubuwan da suka faru da haihuwa kuma ya kara lalata kankara. A halin yanzu, yawancin kwararar kankara ta Antarctic da kuma asarar taro ba su lissafa asarar taro saboda hydrofracture ba. 

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