• • 5:' 1. :'()Il . 551. 55 .1 . Prediction of Asian summer monsoon onset using the new JMA global model MASATO S GI Japan , \! ('Ienrolog;ral Aj(t'my . Tokyo. Japan ffi't - JJI"1Pr 'i; 1fr.:rf'l'if 1JiB fT wi nr ,;'t9" &"": 3ft7 p IS !;j"fn'tf 'r. T. -e; ':Ilirrr h;r." lfT I1 'I Of. f'1'; Iffl l' rr lT, l1 r-r %7 'TfTl2JTllr::r.J 1fr f'f."llT 'flIT trT I t" if, 'if'r*·orT. iT:.rT n:1l lfH -1; fq:f,TJf "f I q "rmrloi 'n1 7 ;:r Of I ii::r f:r. SIT flJ9'" 1I i"1: PT it f.t lTt I h :'=r!';f ::r ;'lf. l1 :JT'l' if h;Nf i. , ' AHST RACT. Lb illg rh nc.... HoI,\ op..rational gluhal model . some prc Jiction experiments were carried ou t rl1f 1979 end 19H t'l mmsoon o.iscts. The results of the op er at iona l model forecasts for 19HX nusct \\l.' I'C <Ilso examined. In tilC' . '': forecasts. realist ic southwesterly mon soon Ilows developed starting fro m th e pre-onset init tal coudiuon s. In mo I CUSI.'S 1'( lrm: l li ,, 1l and \.k vcl opmcru of synop tic disturbances such .IS u nset von c .... predicted h) the mod el. The accuracv the predictio n of the se di-a urf- n ncc v. h ll \ -c cr. ;1I11'l 1l1 ' 1.\1 A Glohal w ccsru t mo del lcvcl-. Along with the increase of th; resolu tion . all the phyxical p rocess pararne te r izat ion s wen: renewed, By t he -e cha nges. th e new m odel, compa red with the old model, ha s much ... tr onger radia tive coo ling mo re p reci - pitation and more intense tropica l circulations, Th e: out line of the new J \ -1 A opera tio nal g loba l mod el i" show n in Table I. LOlli... 's :...c hclIlc f or surfac e: and level 2 1110de: 1for ,"ert ka l dim, .., jtln Oni ly anal Y/cd va luc Integrati on domain: Glo be Hor izont al re... olution : Triangu lar t runcation ut wa ve- number 63 9(, Gau ...sian latitude , a nd 192 lon gitud e"! 16 Semi-implicit scheme hr for 00 GMT ini tia l. 192 hr for 12 GMT initia l Included. Small sca le smoo t hed No n linear no rma l mode iniriah za- t ion with Monthly averaged albe do. soil 1l10i ,tu rc. icc cover ,pl 'ci fk-d gcographica lly Earth ,urfacc Sea surface temperature Phr Jical {Jaram"t crf:aliolJf ( 11 Surf ace c Xl' hangc' Orogr a phy Initialization Gr id Vertical level ", Tim e integra tion For ecast ti me In March JMA · ... p redi ct io n mod els werc renc wed. rile nev I" glo bul mod cl is :t model with T tH h or i: on tal resolution and Ifl vcrlk al 2. :\l odrl and d lltn There h ave been ma ny n:.lll1.:tical p red i ctio n -tudic. ... of the Asian summer mon -o on on-, ... :L \VG N E selected the 1979 onset a ... one o fth r C:b C'; for the forccact inter- compari son exper imen ts t Tcrnpcrton and Krishnamurti ('/ 01. 1983 ). Among the seven models participated the experiment s, on ly the FS U model rca ..o nah ly well re- produced th e on ... ct vo r tex , s howi ng the di fficulty or the forecast of mo nso o n o rr-ct . Kershaw (19H4) co n- du cted :)Ol11e cxp erimcnt-, on the same case and showed th e impor tance of initial ana lysis . Kcrshuw (19M5) further showed th c ..en ... itivih of the predicti on of onse t vortex to the sea surface temperatu re of the Arabian SC;l. At Kanumitvu (19S11.t1 ..o took the same c..l.., e and carried out prediction experimen t. In hi.:; cxpe r i- rn c.u , global aspects of the monsoon on -, et were p red i- cted well . wh ile th e local a ..pcct-, such as [ 11 ;: for m at ion of onset vortex were n ot \\ 1.'11 predicted. M o re rece nt ly. Ku ma (1988) studied the 1986 onset, a nd rev ea led the import ant role of th e co nvec tiv e hea tinc over the western Pacific region on the develop ment and we-award sh ift or the Tibetan high. Using the new ope ra tiona l g lo ba l mo de l. ..o rne mllrc predi ction c\p.:rim cll1s we re car ried out fo r the 1979 and 1986 o'''e l. In thi, paper. the re, ults or the ,e e.'tperiment arc pre,cnteu and di'ctl"i ';t, 'd. The rC"iul r... of thc opcrational gloh' !1 IlHl d'."l fPi lhe on'c t rerin d arc a l,o di "cu""l'd I. lntroductlon • ( :!(i9 )