Amasu Okulingisa Isimo Sezulu Sekhompyutha
Ukumodela isimo sezulu ngokubala kuwumzamo wesayensi wokumelela uhlelo lwesimo sezulu soMhlaba—isimo sezulu, ulwandle, umhlaba, iqhwa, kanye ne-biosphere—ngendlela yezibalo ezilingiswa ngamakhompyutha. Umgomo akukhona nje “ukubikezela isimo sezulu,” kodwa kunalokho ukuqonda ukuziphatha kwesimo sezulu kwesikhathi eside, ukuhlola umthelela wemisebenzi yabantu, nokuhlola izimo zesikhathi esizayo ngokusekelwe ezinguqukweni ekukhishweni kwamagesi okushisa ukushisa, ukusetshenziswa komhlaba, kanye nezici zemvelo njengokuqhuma kwezintaba-mlilo kanye nokushintshashintsha kwelanga. Ngenxa yokuthi isimo sezulu siwuhlelo oluyinkimbinkimbi, ukumodela isimo sezulu kuncike ezinhlobonhlobo zamasu okusebenzisa izibalo ahambisanayo, kusukela kumamodeli angokomzimba asekelwe ku-equation kuya ezindleleni zezibalo kanye nokufunda komshini.
1. Amamodeli asekelwe ezibalweni ezibonakalayo (Amamodeli Anamandla)
Indlela eyisisekelo kakhulu ekubumbeni isimo sezulu ukubumbana okuguquguqukayo, okwakha amamodeli avela emithethweni yemvelo eyaziwayo. Empeleni, ukuguquguquka komkhathi nolwandle kuchazwa ngezilinganiso ezihlukile ezingaphelele njengezilinganiso zeNavier-Stokes (zamanzi), izilinganiso ze-thermodynamics (amandla), ukulondolozwa kobuningi (ukuqhubeka), kanye nezilinganiso zokuthuthwa komphunga wamanzi noma usawoti. Ngenxa yokuthi lezi zilinganiso azinazo izixazululo ezilula zokuhlaziya esikalini seplanethi, amakhompyutha asetshenziselwa ukwenza ukuhlanganiswa kwezinombolo ngokuhamba kwesikhathi.
Amamodeli e-climate dynamics avame ukuhlukaniswa abe yizingxenye eziningana: umkhathi, ulwandle, umhlaba, iqhwa lolwandle, futhi ngezinye izikhathi i-chemistry yomkhathi. Ukusebenzisana phakathi kwalezi zingxenye kuhlanganiswa ngokushintshana kwamandla, umswakama, umfutho, kanye nokushintshana kwekhabhoni. Inzuzo yendlela ebonakalayo ukuvumelana kwayo nezimiso eziyisisekelo zemvelo; izinkinga zayo izindleko zayo zokubala kanye nokuthembela kwayo ekwenzeni lula izinqubo ezincane kakhulu (isb., amafu ajikelezayo).
2. Ukuhlukanisa igridi kanye nokulungiswa kwendawo kanye nesikhathi
Ngenxa yokuthi uMhlaba uyaqhubeka, amamodeli adinga amasu okuhlukanisa: ubuso nomkhathi kuhlukaniswe ngamaseli egridi (izikwele) ngezingqimba ze-latitude-longitude kanye nezendlalelo eziqondile. Isixazululo segridi (isb., 100 km, 25 km, noma esincanyana) sinquma imininingwane engamelwa. Uma isinqumo sincanyana, izinqubo eziningi zendawo zingabonakala ngokucacile, kodwa izidingo zokubala zanda kakhulu.
Ngaphezu kwegridi yendabuko ye-latitude-longitude, amanye amamodeli asebenzisa igridi ye-cubic-spherical noma izindlela ze-finite element ukunciphisa izinkinga zezinombolo eduze kwezinsika. Ukukhetha isinyathelo sesikhathi nakho kubalulekile: isinyathelo sesikhathi esikhulu kakhulu singenza imodeli ingazinzile, kuyilapho isinyathelo esincane kakhulu sinciphisa ijubane lokulingisa. Ngakho-ke, izinhlelo ezithile zezinombolo—njenge-semi-implicit noma i-split-explicit—zisetshenziselwa ukugcina ukuzinza ngenkathi zihlala zisebenza kahle.
3. Ukuhlelwa kwezinqubo zegridi engaphansi
Izinqubo eziningi ezibalulekile zenzeka ezikalini ezincane kunezisele zegridi, njengokwakheka kwamafu, ukuxokozela kwezingqimba zomngcele, imvula eguquguqukayo, noma ukusebenzisana kwe-aerosol namafu. Ngenxa yokuthi azikwazi ukulingiswa ngokucacile ezinqumweni zomhlaba ezivamile, zimelelwa yimingcele: imithetho ye-empirical noma ye-semi-empirical ehlobanisa izimo zesikali segridi nemiphumela emaphakathi yezinqubo ezincane.
Ukulinganisa kungenye yemithombo emikhulu yokungaqiniseki ekubikezelweni kwesimo sezulu, ikakhulukazi maqondana namafu, athinta ukubonakaliswa koMhlaba (i-albedo) kanye nempendulo yemisebe. Amasu esimanje okulinganisa ahlanganisa izindlela zokulinganisa ezi-stochastic, ezifaka izinto ezingaba khona ukuze zimele ukuhlukahluka okuncane okungaxazululwa yigridi.
4. Amamodeli okujikeleza okuvamile kanye namamodeli esistimu yoMhlaba (GCM kanye ne-ESM)
Amamodeli ezulu omhlaba aziwa kakhulu yi-General Circulation Models (GCMs), alingisa ukujikeleza komoya kanye/noma kolwandle ngezinga leplanethi. Amamodeli aphelele aziwa ngokuthi ama-Earth System Models (ESMs), anezela imijikelezo ye-biogeochemical efana nemijikelezo ye-carbon ne-nitrogen kanye ne-vegetable dynamics. Ngama-ESM, abacwaningi bangacwaninga hhayi kuphela impendulo yokushisa ekukhishweni komoya kodwa nokuthi ukuguquka kwesimo sezulu kuthinta kanjani ikhono lezinto eziphilayo lokumunca i-carbon, ngaleyo ndlela kudale impendulo yesimo sezulu ne-carbon.
Ezingeni lokusetshenziswa, lo modeli usetshenziselwa ukuzama "izimo": isibonelo, ukuthi isimo sezulu singathuthuka kanjani uma ukukhishwa kwegesi kuqhubeka nokwenyuka, kuhlala kuzinzile, noma kwehla ngokushesha. Imiphumela yakha isisekelo sezifundo zesayensi zomhlaba wonke futhi inika ulwazi ngenqubomgomo yesimo sezulu.
5. Ukwehlisa izinga: kusukela emhlabeni wonke kuya esifundeni
Izidingo zomsebenzisi zivame ukuba zezasendaweni: umthelela emvuleni yasemadolobheni, amazinga okushisa aphezulu ezindaweni zezolimo, noma ingozi yezikhukhula zasemfuleni. Ngenxa yokuthi amamodeli omhlaba wonke avame ukuba mancane kakhulu ngemininingwane yendawo, kusetshenziswa amasu okwehlisa izinga.
Kunezindlela ezimbili eziyinhloko. Okokuqala, ukwehlisa izinga nge-dynamical nge-Regional Climate Model (RCM), esebenzisa imodeli enesinqumo esiphezulu esifundeni esithile enemikhawulo yemodeli yomhlaba wonke. Okwesibili, ukwehlisa izinga ngezibalo, okusungula ubudlelwano bezibalo phakathi kwezinguquko ezinkulu (isb., ukujikeleza komoya) kanye nezinguquko zendawo (imvula yesiteshi). Ukwehlisa izinga ngezibalo kushibhile kodwa kuncike ekucabangeni ukuthi ubudlelwano bezibalo obudlule buzoba khona esikhathini esizayo.
6. Ukuhlanganiswa kwedatha ukuze kwakhiwe kabusha imodeli kanye nokuvumelana kwayo
Nakuba ukuhlanganiswa kwedatha kwaziwa kakhulu ekubikezeleni isimo sezulu, le ndlela ibalulekile nasekuboniseni isimo sezulu, ikakhulukazi ekuhlaziyeni kabusha kanye nokwakha kabusha izimo zesimo sezulu zomlando. Ukuhlanganiswa kwedatha kuhlanganisa ukubonwa (isathelayithi, isiteshi, umkhumbi, i-buoy) kanye namamodeli angaphambili ukukhiqiza izilinganiso ezihambisanayo ngokomzimba zesimo somkhathi nolwandle.
Izindlela ezidumile zifaka phakathi i-Kalman Filter (kanye nezinto ezitholakala kuyo njenge-Ensemble Kalman Filter) kanye nezindlela eziguquguqukayo (3D-Var/4D-Var). Esimweni sezulu, ukuhlanganiswa kusiza ukuhlanganisa idatha ehlakazekile nengaphelele, kunikeze imikhiqizo yomlando ewusizo ekuhloleni amamodeli nokuqonda izitayela zesikhathi eside.
7. Ukumodela kweqembu lonke kokungaqiniseki kanye namathuba
Isimo sezulu siyaphithizela, ngakho-ke imiphumela yokulingisa iyazwela ezimweni zokuqala kanye nokukhetha kwamapharamitha. Ukuze kufezwe lokhu, kusetshenziswa imodeli yeqembu: ukusebenzisa imodeli izikhathi eziningi enezimo zokuqala ezahlukahlukene, izimo, noma amapharamitha ukukhiqiza amathuba ahlukahlukene. Ama-Ensemble avumela abacwaningi ukuthi bahlole amathuba esigameko (isb., ukuphindeka kabili kwethuba legagasi lokushisa okukhulu) kunokuba kube yindlela eyodwa yomphumela.
I-Ensemble iphinde isekele ama-ensembles amamodeli amaningi, ahlanganisa amamodeli amaningi avela ezikhungweni ezahlukene. Ukuqhathanisa phakathi kwamamodeli kuyasiza ekuboneni izici eziqinile (ezihambisanayo) kanye nalezo ezingakaqiniseki.
8. Ukuhlolwa kwemodeli kanye nokulinganiswa kokusebenza (ukuqinisekiswa kwemodeli)
Amasu okumodela awagcini nje ekusebenziseni ukulingisa; ukuhlolwa kwemodeli kubaluleke ngokulinganayo. Amamodeli aqhathaniswa nokubonwa komlando, ukuhlaziywa kabusha, kanye namarekhodi e-paleoclimate (isb., ama-ice cores noma ama-sediment) ukuqinisekisa ikhono lawo lokukhiqiza kabusha amaphethini okushisa, imvula, ukujikeleza kwe-monsoon, i-El Niño–La Niña, kanye nemikhuba yokufudumala komhlaba. Izindlela zokuhlola zifaka phakathi izibalo zokulinganisa (ukubandlulula, i-RMSE, ukuhlangana), ukuhlaziywa kwe-extremes, kanye nokuhlolwa kokulondolozwa kwamandla namanzi.
Ukuhlolwa kwanamuhla kugcizelela nokuhlola okusekelwe enqubweni: hhayi nje ukufanisa izinombolo, kodwa nokuhlola ukuthi imodeli iphinda ikhiqize yini izinqubo ezifanele zomzimba, isibonelo izindlela zokwakheka kwamafu ezindaweni ezishisayo noma ukuguquguquka kwemisinga emikhulu yolwandle.
9. Ukufunda komshini kanye namamodeli e-hybrid
Eminyakeni yamuva nje, ukufunda komshini (i-ML) sekuyindlela ehambisanayo. I-ML isetshenziselwa ukusheshisa izingxenye ezibizayo (ukumodela okungesinye), ukulungisa ukucwasa (ukulungiswa kokucwasa), noma ukwakha amapharamitha amafu kanye nokuxokozela okufundwe ekulingiseni okunesisombululo esiphezulu kakhulu kanye nedatha yokubuka.
Indlela ethembisayo iyimodeli ehlanganisiwe: ukuhlanganisa umongo ongokoqobo (ukugcina ukuvumelana nemithetho yokonga) nemodyuli ye-ML yezinqubo ze-sub-grid. Izinselele ezinkulu ukwenziwa okubanzi ngale kobubanzi bedatha yokuqeqesha, ukuhunyushwa, kanye nokuqinisekisa ukuzinza kwezinombolo lapho i-ML ihlanganiswa kumamodeli wesimo sezulu sesikhathi eside.
10. Ukusebenza kahle kwekhompyutha kanye nokusebenza kahle kwamandla
Ukumodela isimo sezulu kwanamuhla kusebenza kuma-supercomputer anama-core ekhompyutha ayizinkulungwane kuya kwezigidi. Amasu okulinganisa, ukwenza ngcono ikhodi, kanye nokuphathwa kokufakwa kwedatha nokukhishwa kwayo kubalulekile. Izinqumo eziphakeme kakhulu kanye nama-ensemble amakhulu akhiqiza ama-petabyte edatha, okwenza ukuphathwa kwedatha, ukucindezela, kanye nokuhlaziywa kwedatha (ukucubungula idatha ngenkathi ukulingisa kusebenza) kubaluleke kakhulu.
Ukufika kwama-GPU kanye nezakhiwo ezintsha zekhompyutha kuholele ekuthuthukisweni kabusha kwamamodeli ukuze asebenze kahle kakhulu. Okwamanje, umphakathi wesimo sezulu nawo uqala ukucabangela umthelela wekhabhoni wekhompyutha, okwenza ukusebenza kahle kungabi yindaba yesikhathi kuphela kodwa nokusetshenziswa kwamandla.
I-Penutup
Amasu okumodela isimo sezulu ngokubala ahlanganisa i-physics, izibalo zezinombolo, izibalo, isayensi yedatha, kanye nokubala okusebenzayo okuphezulu. Kusukela kumamodeli aguquguqukayo asekelwe ku-equation, ukuhlukanisa igridi, kanye nokulinganisa i-sub-grid, kuya kuma-ensembles, ukwehlisa izinga, ukuhlanganisa idatha, kanye nokuhlanganiswa kokufunda komshini, konke kuhlose ukuqonda uhlelo lwesimo sezulu oluyinkimbinkimbi nokunikeza ulwazi oluthembekile. Njengoba ukubonwa, imibono, kanye namakhono okubala kuthuthuka, ukumodela isimo sezulu kuzokwazi ukuphendula imibuzo ephuthumayo: ukuthi isimo sezulu sishintsha kanjani, ukuthi sishintsha ngokushesha kangakanani, nokuthi yimaphi amasu azosebenza kahle kakhulu ekunciphiseni nasekuzivumelaniseni nesikhathi esizayo.
