Ithonya Lemifudlana Yasolwandle Ekushintsheni Kwesimo Sezulu Somhlaba Wonke Ezifundweni Zokubuka Ulwandle Ezibonakalayo
Ukushintsha kwesimo sezulu emhlabeni wonke akunqunywa nje kuphela yimisebenzi yabantu emhlabeni, kodwa futhi kuthonywa kakhulu yizimo zolwandle. Ku-oceanography ebonakalayo, imisinga yolwandle ibhekwa njenge "zinjini zokuthutha" zamandla eMhlabeni: ukuhambisa ukushisa, usawoti, kanye nobuningi bamanzi kusuka esifundeni esisodwa kuya kwesinye. Ngenxa yokuthi izilwandle zigcina ukushisa okweqile okubangelwa ukwanda kwamagesi okushisa, indlela ukushisa okusatshalaliswa ngayo imisinga izonquma amaphethini esimo sezulu, ukuqina kwesiphepho, ukuguquguquka kwezinga lokushisa, ngisho nezinguquko ohlelweni lwesimo sezulu oluphakathi kwamazwekazi. Ukuqonda imisinga yolwandle kusho ukuqonda enye yezinto ezibangela isimo sezulu somhlaba wonke.
1. Imisinga yolwandle njengabathuthi bokushisa kanye nabalawuli bokusatshalaliswa kwamandla
Imisinga yolwandle yakhiwa yinhlanganisela yamandla omoya, umehluko wobuningi (othonywe yizinga lokushisa kanye nosawoti), ukujikeleza koMhlaba (umphumela weCoriolis), kanye nesimo sezitsha zolwandle. Ngezinga elikhulu, imisinga yakha uhlelo lokujikeleza oluhambisa ukushisa kusuka ezindaweni ezishisayo, ezithola ukukhanya kwelanga okuningi, kuya ezindaweni eziphakeme ezipholile. Le nqubo izinzisa isimo sezulu somhlaba: ngaphandle kwemisinga yolwandle, izindawo ezishisayo beziyoba zifudumele kakhulu, kanti izindawo ezisenyakatho bezizoba zibanda kakhulu.
Isibonelo esaziwa kakhulu yi-Gulf Stream kanye nokwelulwa kwayo, i-North Atlantic Current, ethwala amanzi afudumele aye eNyakatho Atlantic. Lo mthombo unegalelo esimweni sezulu esifudumele saseNtshonalanga Yurophu uma kuqhathaniswa nezinye izifunda eziku-latitude efanayo. Kusukela embonweni we-oceanographic ongokoqobo, lokhu kubonisa ukuthi ukukhuphuka kokushisa (ukudluliselwa kokushisa ngokuhamba kwamanzi amaningi) kungashintsha kanjani isimo sezulu sesifunda kakhulu.
2. Ukujikeleziswa kwe-thermohaline kanye "nebhande lokuhambisa" lomhlaba wonke
Ngaphezu kwemisinga engaphezulu eqhutshwa ngumoya, kukhona ukujikeleza okujulile, okuqhutshwa ubuningi okwaziwa ngokuthi ukujikeleza kwe-thermohaline. Umehluko wobuningi uvela ekupholiseni, ekuhwamukeni, ekuqandeni kweqhwa lolwandle (okwandisa usawoti wamanzi asele), kanye nokufakwa kwamanzi ahlanzekile okuvela emvuleni naseqhweni okuncibilikayo. ENyakatho ye-Atlantic, amanzi angaphezulu angabanda futhi abe nosawoti owanele ukucwila ukuze akhe izinqwaba zamanzi ajulile (isb., Amanzi Ajulile AseNyakatho ye-Atlantic). Lawa manzi abe esegeleza phansi ekujuleni kolwandle aye eningizimu yezwe futhi axhumane nezinqubo zokuphakama kwezinye izindawo.
Lolu hlelo luvame ukubizwa ngokuthi “ibhande lokuhambisa lomhlaba,” nakuba empeleni luyinkimbinkimbi kakhulu. Kodwa iphuzu elibalulekile lisobala: ukujikeleza kwe-thermohaline kuxhumanisa izilwandle zomhlaba, kuthuthe ukushisa nekhabhoni ngokuhamba kwesikhathi kusukela emashumini kuya emakhulwini eminyaka. Uma lokhu kujikeleza kuba buthaka noma kushintsha, amaphethini okufudumala komhlaba kanye nezimo zezulu zesifunda nakho kungashintsha.
3. Imisinga yolwandle kanye nempendulo yesimo sezulu
Imisinga yolwandle ayiphenduli nje kuphela ekushintsheni kwesimo sezulu kodwa futhi ingasiqinisa noma isinciphise. Ku-oceanography ebonakalayo, impendulo ebalulekile ihlanganisa:
1. Impendulo yeqhwa-i-albedo: Imisinga ethwala ukushisa iye ezindaweni ezibandayo ingasheshisa ukuncibilika kweqhwa lolwandle. Njengoba iqhwa lolwandle lincipha, ubuso bolwandle obumnyama bumunca imisebe yelanga eyengeziwe, okwandisa ukufudumala kwendawo kanye nokusheshisa ukuncibilika.
2. Impendulo yokugeleza kwamanzi ahlanzekile: Ukuncibilikisa iqhwa laseGreenland kanye nokwanda kwemvula ezindaweni eziphakeme kwengeza amanzi ahlanzekile eNyakatho ye-Atlantic. Amanzi ahlanzekile anciphisa usawoti kanye nokuminyana, ngaleyo ndlela avimbele ukwakheka kwamanzi ajulile. Lokhu kunamandla okwenza buthaka ukujikeleza kwamanzi amakhulu njenge-Atlantic Meridional Overturning Circulation (AMOC).
3. Ukushisa kolwandle–impendulo yesimo sezulu: Izinguquko emisinga zingashintsha izinga lokushisa kolwandle (SST). I-SST ithonya ukuhwamuka, ukwakheka kwamafu, amaphethini okucindezela komoya, kanye nezindawo zemvula. Ngamanye amazwi, imisinga yolwandle ilawula “uphethiloli” womkhathi.
Lezi zibonelo ezintathu zibonisa ukuthi izinguquko ezincane ekujikelezeni kwegazi zingabangela imiphumela yochungechunge ohlelweni lwesimo sezulu.
4. I-ENSO: isibonelo sokusebenzisana kwemisinga, imimoya, nesimo sezulu somhlaba wonke
Isenzakalo se-El Niño–Southern Oscillation (ENSO) siyisibonelo esivelele sokuxhumana kwemisinga nesimo sezulu. Olwandlekazini olushisayo lwasePacific, imimoya yezohwebo ivame ukusunduza amanzi afudumele ngasentshonalanga, kuyilapho amanzi abandayo, acebile ngezakhamzimba ekhuphukela ngasempumalanga. Ngesikhathi se-El Niño, imimoya yezohwebo iyancipha, imisinga kanye nezinga lokushisa kuyashintsha, ukukhuphuka kuyancipha, futhi amanzi afudumele anda aye ePacific ephakathi nendawo. Imithelela isakazeka emhlabeni wonke ngokuxhumana komoya: izinguquko emaphethini emvula eNingizimu-mpumalanga ye-Asia nase-Australia, ukwanda kwemvula ezingxenyeni zaseNingizimu Melika, kanye nokuphazamiseka kwamaphethini esiphepho ezindaweni ezahlukene.
Ngokombono wezolwandle, i-ENSO ikhombisa ukuthi izinguquko emifuleni engaphezulu kanye namagagasi kaKelvin/Rossby olwandle zingaguqula kanjani isimo sezulu phakathi kwezinkathi zonyaka ngisho nangaphakathi kweminyaka. Ngokuphathelene nokushintsha kwesimo sezulu, kunesithakazelo esikhethekile sokuthi ukufudumala komhlaba kuzoshintsha yini ubukhali, imvamisa, noma izici ze-ENSO, yize lokhu kusalokhu kuyisihloko socwaningo olusebenzayo ngenxa yobunzima bokusabela kolwandle nomoya.
5. Indima yamandla kagesi ekugcineni ukushisa kanye "nokuphumula" kokushisa komhlaba
Ulwandle lungamunca ukushisa okukhulu, lukugcine ezingqimbeni eziphezulu noma lukudlulisele ekujuleni ngokuxuba okuqondile, ukudlulisa umoya, kanye nokujikeleza kwe-thermohaline. Kwezinye izikhathi, ukufudumala kokushisa komoya ongaphezulu kubonakala kuhamba kancane uma kuqhathaniswa nomkhuba wesikhathi eside. Enye incazelo esekelwa yizifundo ezahlukahlukene ukuthi ukushisa okwengeziwe "kudonswa" olwandle, ikakhulukazi ngaphansi komhlaba, ngenxa yezinguquko emimoyeni nasemisingeni.
Lokhu kusho ukuthi imisinga yolwandle ithonya indlela ukufudumala komhlaba “okuvela ngayo” ebusweni. Ukufudumala akunyamalali, kodwa kungasatshalaliswa ngendlela ehlukile ngaphakathi kohlelo lolwandle nomoya-mpilo, kuthonye imibono kanye nokuguquguquka kwesimo sezulu sesikhathi esiphakathi.
6. Imisinga yolwandle, ikhabhoni, kanye nezixhumanisi zokushintsha kwesimo sezulu
Nakuba ukugxila okuyinhloko kwe-oceanography yemvelo kuyi-dynamics, imisinga nayo idlala indima ebalulekile emjikelezweni wekhabhoni. Imisinga engaphezulu ilawula ukushintshaniswa kwe-CO₂ phakathi kolwandle nomoya, kuyilapho ukujikeleza okujulile kugcina ikhabhoni encibilikisiwe isikhathi eside. Ukuphakama phezulu kungaletha amanzi acebile ngekhabhoni ebusweni, okungabe sekukhipha i-CO₂ emoyeni, kuye ngezimo zamakhemikhali kanye ne-biological. Ngokuphambene nalokho, izindawo zamanzi acwilayo zingavala ikhabhoni ekujuleni.
Ngamanye amazwi, ukushintsha kwemisinga kungashintsha ikhono lolwandle lokusebenza njengesinki sekhabhoni. Uma leli khono lehla, izinga lokuqongelela kwe-CO₂ emoyeni linganda, kusheshiswe ukufudumala komhlaba.
7. Umthelela wezinguquko emifudlaneni yolwandle esimweni sezulu esibi kakhulu kanye nemvelo
Izinguquko emisinga kanye namazinga okushisa olwandle zingandisa amathuba okuba kube namagagasi okushisa olwandle, okungaholela ekukhanyeni kwamakhorali, kushintshe izindawo zokuhlala zezinhlanzi, futhi kuphazamise uchungechunge lokudla. Ngokombono womoya, ama-SST afudumele angaqinisa iziphepho zasezindaweni ezishisayo ngokunikeza amandla afihliwe ngokuhwamuka. Imisinga efudumeza izindawo ezithile noma eyandisa isikhathi samanzi afudumele ingandisa ingozi yokwanda kwesiphepho.
Ngaphezu kwalokho, izinguquko emifudlaneni yasogwini zingathinta amaphethini emvula, amaphethini enkungu, kanye namazinga okushisa omhlaba eduze nogu. Ezimweni eziningi, ukuguquka kwesimo sezulu kuqinisa ukuhlukaniswa kolwandle, kunciphisa ukuxubana, futhi kungenza buthaka ukuhlinzekwa kwezakhamzimba ezivela ekujuleni. Ngokwemvelo, lokhu kuphinde kuhlotshaniswe nokuguquguquka kwamanje kanye nokuqina kwekholomu yamanzi.
8. Izinselele zocwaningo kanye nezindlela zokucwaninga ngezolwandle ezibonakalayo
Ukuhlola ithonya lemisinga yezulu emhlabeni kudinga ukubonwa kanye nokwakheka kwemodeli. Izinsimbi ezifana ne-Argo floats, i-altimetry yesathelayithi, ama-drifter, ama-Acoustic Doppler Current Profilers (ama-ADCP), kanye nama-transoceanic moorings asetshenziselwa ukumaka imisinga kanye nokuguquguquka kwezinga lokushisa nosawoti. Amamodeli okujikeleza kolwandle kanye namamodeli esimo sezulu emhlabeni wonke asiza ukuhlola izimo zokushintsha, okuhlanganisa izimpendulo ze-AMOC, izinguquko ekukhuphukeni, kanye nokushintsha kwamaphethini wamanje ongaphezulu.
Izinselele zibalulekile ngoba ulwandle luyaphithizela, lunezilinganiso eziningi, futhi lusebenzisana kakhulu nomoya. Ukungaqiniseki kuvela futhi kudatha yomlando elinganiselwe ezindaweni ezikude (isb., i-Southern Ocean) kanye nobunzima bezinqubo zokuxuba ezincane okunzima ukuzimelela kumamodeli.
Isiphetho
Ku-oceanography ebonakalayo, imisinga yolwandle iyisici esibalulekile esilawula ukusatshalaliswa kokushisa, sithonya umjikelezo wekhabhoni, futhi sibumba amaphethini esimo sezulu sesifunda nesomhlaba wonke. Imisinga yomhlaba eqhutshwa ngumoya kanye nokujikeleza kwe-thermohaline kusebenza ndawonye njengohlelo olukhulu lokuthutha, olungaqinisa isimo sezulu ngenkathi futhi ludala ukuguquguquka njenge-ENSO. Lapho ushintsho lwesimo sezulu lushintsha izinga lokushisa, usawoti, imimoya, kanye nokufakwa kwamanzi ahlanzekile, imisinga yolwandle ingashintsha ngokufanele—futhi lezo zinguquko zingaphinde zibuye, ziqinise noma zishintshe indlela yokushintsha kwesimo sezulu.
Ngakho-ke, ukuqonda imisinga yolwandle akuyona nje indaba yesayensi yasolwandle, kodwa kuyisisekelo esibalulekile sokubikezela ukuguquka kwesimo sezulu, ukuklama amasu okuzivumelanisa nezimo ogwini, nokugcina ukuqina kwezindawo zemvelo zasolwandle kanye nezinsiza. Ukuqaphela isikhathi eside kanye nokulingisa okuthuthukayo kuyisihluthulelo sokuqonda "ukushaya" kolwandle okulawula isimo sezulu soMhlaba.
