Nghien ctfu & Trao doi NGHIEN CtfU KHA NANG Dl/BAO SlTXUAT HIEN TIEN TRIEN
CUA AP THAP NHIET DCfl VA BAO TRl/OiC NHIEU NGAY
TREN BIEN DONG BANG CONG CU MO HINH SO TRI TREN MIEN HAN CHE ETA
TS. D§ Ngoc Thang
Trung tam Dif bao Khi tifdng Thiiy van Trung ifdng
V
r di trudng hgp can bdo so 2 - 2007 (ten qud'c te0704), md hinh dU bdo thdi tiet khu vUc ETA dd dugc chgy dU bdo +168h (7 ngdy) vdi 2 sa do tham sd hda ddi luu BMJ vd KF, bang sdlieu ddu vdo Id md hinh todn cau GFS cHa NCEP (My). Tren casdphdn tich vd tinh todn khoang cdch tic vi tri tdm bdo thUc den vi tri tdm bdo du bdo, dd cd the nhdn thay quy dgo di/bdo cua sado tham sdhda ddi luu Kain-Fritsch (KF) td't han han so vdi vdi sado BMJ trong trUdng hgp ndy. Dieu dd gdp phdn minh hoa khd ndng bieu dien ddng van chuyen khd'i lugng cua dd'i luu trong bdo cua sa do KF Id rat khd quan, vd dong thdi cdng ggi y cd the si^ dung md hinh ETA vdi sado KF de tham khdo khi cd hinh the cd bdo hade ATND hogt ddng tren bien Ddng.1. MoT dau
Md hinh dif bao thdi tie't nghiep vit tren mien ban che (ciing cdn cd the goi la mo hinh khu vifc) ETA da du'dc nghien ctJu tai Viet Nam tif khoang 10 nam nay [7], de'n nay, qua nghien ctJu va iJng diing thii' nghiem, da td ra cd ke't qua kha tot va da du'dc tJng diing chinh thiJc vao nguon thong tin tham khao cho dtj'bao nghiep via ban ngan tai Trung tam Dif bao Khi tu'dng Thiiy van Trung u'dng (TT DB KTTV TLf) tii' nam 2006. Nhd kha nang cung cap dn dinh ciia so' heu md hinh toan cau GFS bdi NCEP (My) vdi thdi ban dif bao 180h (tiJc 7,5 ngay-dem), chiing tdi khdng nhitng da chay du"
bao han ngan (3 ngay dem), ma cdn cd the chay dif bao ban vifa (7,5 ngay dem) vdi md hinh ETA de cung cap thdng tin tham khao cho dif bao nghiep vu ciia Phdng DB Han vii'a - Han dai ciia TT DB KTTV TlT.
Hinh the Synop difdc xet d day la cdn bao so' 2 (nam 2007), cd ky hieu qud'c te "0704". Day
la cdn bao khong manh, hinh thanh ivi mdt ATND tren bien Ddng. Mac dii cap do gid khdng Idn, nhifng gay mifa va lu lut nghiem trong cho Tay Nguyen va Mien Trung ciia Viet Nam vdi nhiJng thiet hai ve ngifdi va ciia lai rat Idn nhif bao chi va cac phifdng tien thdng tin dai chiing da difa tin.
Bang phifdng phap chay thiJ nghiem md hinh so'tri ETA vdi 2 sd do tham so hda dd'i lifu Kain - Fritsch (KF) va Belts - Miller - Janjic (BMJ) cd so sanh vdi san pham DBST ciia Nhat Ban, chiing tdi mud'n khao sat va so sanh kha nang dif bao sif xua't hien va quy dao ciia ATND (va sau do la cdn bao so' 2) vdi cdng cu duf bao la md hinh so' tri khu viJc ETA.
2. Tdm tat ve crfn bao so'2
Diln bie'n ciia cdn bao nay difdc cho trong bang 1 the hien quy dao thifc ciia cdn bao tif liic cdn la ATND (theo sd lieu ciia TT DB KTTV TU):
Ngifdi phan bien: ThS. Do Le Thuy
Tap chi Khi tifgTng Thuy van * Thang 5/2008 13
Nghien cuTu & Trao doi
Bang 1. Vi tri, ciidng dg cua cdn bdo so'2 (ndm 2007)
So'TT 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Ngay 01-8-2007
02-8-007
03-8-2007
04-8-2007
05-8-2007
06-8-2007
07-8-2007
Gid (QT) OOz 06z 12z 18z OOz 06z 12z 18z OOz 06z 12z 18z OOz 06z 12z 18z OOz 06z 12z 18z OOz 06z 12z 18z OOz 06z 12z 18z
Kinh do 114,0 114,1 114,3 114,3 114,0 113,7 113,2 113,1 113,1 112,8 112,5 112,6 112,5 111,4 110,1 109,9 109,6 109,5 109,5 109,5 109,3 109,3 108,5 108,0 107,6 107,3 107,0 106,1
VTdo 12,5 12,6 12,6 12,6 12,5 12,7 12,7 12,8 13,2 13,6 13,6 13,6 13,7 14,0 14,3 14.3 14,3 14,3 14,8 15,5 16,6 17.0 17.6 18.0 18,3 18.5 18,2 18.1
Pmin Mb 1002 1000 1000 1000 1000 1000 1002 1002 1002 1002 1002 998 998 998 998 998 996 996 996 996 998 998 1000
998 998 998 998 998
Vmax Kts m/s 33 16,5 32 16,0 32 16,0 32 16,0 32 16,0 30 15,0 30 15,0 30 15,0 30 15,0 30 15,0 30 15,0 35 17,5 35 17,5 35 17,5 35 17,5 35 17,5 35 17,5 35 17,5 35 17,5 35 17,5 35 17,5 30 17,5 30 17,5 30 17,5 25 12,5 25 12,5 30 15,0 30 15,0
Tif bang 1 nhan thay khoang thdi gian OOz ngay l-VIIl-2007 (TiJc 07h ngay l-VlIl-2007 theo gid Ha noi) bat dau hinh thanh ATND. Vao liic 23h30 gid Ha Noi, ngay 31-VII, Trung tam Difbao KTTV TLf bat dau phat ban tin "khan ca'p" va dif bao (xem hinh 1 va 2). Ngay 5-V1II-2007, bao sd 2 xuo'ng sau nhat (Pmin = 996 mb), van td^c gio cifc dai dat khoang 17,5 m/s. Cho de'n ngay 8-VIlI- 2007 thi suy yeu va tan ra.
Nhifbang 1 cho thay, tuy gio bao chi dat cap 8, nhUng lu'dng mUa tai Tay Nguyen va Mien trung rat Idn, da gay 10 lut nghiem trong (vi du: mUa tich luy 24h tai Bao Loc- Lam Dong ngay 4-VIII la 123 mm; tai Hu'dng Khe - Ha TTnh ngay 5-VIII la 151mm...).
Hinh 1. Diidng di cua bdo sd'2 (ndm 2007) theo TT DB KTTV Tif
14
Tap chi Khi tifc^ng Thuy van * Thang 5/2008
Nghien ciJu & Trao doi
^.Hinh 2. Bdn do phdt tin vd dUbdo bdo sd'2 cda TTDB KTTV TLf vdo ldc 22h30 gid HN ngdy 31-7-2007, khi cdn bdo con Id ATND.
3. So sanh kha nang di]f bao ve cdn bao so' 2 bang cong cu mo hinh so' trj:
Mot cau hdi cd the difdc dat ra mot each tif nhien la: vdi mot ATND hinh thanh ngay tren Bien Dong nhif tru'dng hdp bao sd' 2, vdi cac md hinh sd'tri da difdc chay va iJng dung d Viet Nam trong khoang gan 10 nam trd lai day, chiing cd kha nang dif bao sdm difdc sif xua't hien nay khdng? Ne'u cd, thi nang life dif bao ciia mdi md hinh dat difdc d miJc nao?
Bo so' heu difdc chon liii lai, la OOZ, ngay 30 - 7 - 2007. Dd'i vdi md hinh ETA, vdi sif lifa chon sd do BMJ, dif bao 48b iJng vdi 07b gid HN, ngay Ol-VIII-2007 duTdc cho tren hinh 3.
Ban dd tifdng iJng ciia mo hinh toan cau ciia Nhat Ban (JMA) difdc cho tren hinh 4.
Nhin tdng the, nhan tha'y md hinh ETA vdi sd do BMJ cho difbao 48b kha td't dd'i vdi vi tri tam bao. Md hinh toan cau ciia JMA dd'i vdi tru'dng hdp dang xet, chu'a chd'ng td kha nang dif bao sif xua't hien ciia ATND nay. Dieu nay
cd the difdc ly giai la do do phan giai ciia md hinh JMA la 1,25 do, thifa hdn nhieu so vdi md hinh khu vifc ETA (1/5 do), do dd nhieu qua trinh quy md nhd cd 30 Ion ciia md hinh JMA bi bd qua va gay nen sai so' vao thdi ban dif bao 48h.
Hinh 3. Bdn do dii bdo 48h trUdng dp sudi miic bien, dUdng dong cua gid cdch be mat 10m vd miia tich luy 24h theo md hinh ETA vdi sddo BMJ
Tap chi Khi tufgfng Thuy van * Thang 5/2008 15
Nghien cufu & Trao doi
30 2007 JMA 1.25^.125
BOE BSE 95 E 95E lOSE UOE USE IME 12SE 120E
Hinh 4. Bdn do dii bdo trUifng dp suat tgi miic bien, dUdiig dong cdch be mat 10m vd lUdng mUa tich luy 24h; Theo san pham ciia mo hinh todn cau JMA.
So sanh dif bao ciia md hinh ETA (hinh 3)
vdi md hinh toan cau JMA (hinh 4) can ciJ vao du'dng ddng vao thdi diem 07h ngay 2-VIII- 2007, chiing ta ciing thay rd: tai Idp khdng khi sat da't, tai toa do IdioangX =114°,(p =13,5° cd the nhan tha'y cac ddng khdng khi hoi tu rd ret, dac trufng cho hoan Imi XTND hoac bao; ngu'dc lai tai Ichu vifc toa do nay tren ban dd ciia JMA khdng nhan tha'y sif hoi tu nhif vay ciia khdng khi tai Idp difdi ciia khi quyen.
De cd the so sanh chat che va day dii hdn, md hinh ETA da difdc chay lai cho bo so' heu 18Z 31-VII-2007, vdi thdi han 168h (7 ngay- dem). Ke't qua thiir nghiem difdc so sanh trong bang 2 dd'i vdi vi tri tam ATND hoac khi thanh bao.
Bang 2. So sanh toa do tdm ATND (hoac bdo) cda dif bdo giita ETA vdi sddo BMJ vd KF ddi vdi so lieu 18Z 31-8- 2007, chgy dU bdo 168h
Dir bao 00 h
06 12 18 24 30 36
^12 48 54 60 66 72 78 84 90 96 102 108 ll^l 120 126 132 138 144 150 156 162 168
Ngay 18z31-7 - 07 OOz 01 8-810-/
06z 12z 18z OOz 02 - 8 - 07
06z 12z 18z OOz 03 - 8 - 07
06z 12z 18z OOz 04 - 8- 0/
06z 12z 18z OOz 0 5 - 8 - 0 7
06z 122 18z OOz 0 6 - 8 - 0 7
06z 12z 18z OOz 07 - 8 - 07
06z 12z 18z
VTd9(ETA) KF
- 12,75 13,05 12,75 12,75 13,25 13,75 13,75 13,25 13,25 13,25 13,25 13,25 13,75 13,75 14.75 15,25 15,25 16,25 16,25 16,75 16,75 16,75 16,75 16,75 16,75 16,25 16.50
Kinh dp (ETA) KF
- 115,00 114,80 115.75 116,25 116.75 116,25 115,75 115,25 115,25 114,75 114,25 114,25 113,75 113,75 113.25 112.75 112,25 111,75 111,25 110,25 109.75 109,25 109.25 108.75 107,75 106,75 106.20
16
Tap chi Khi tiTrfng Thuy van * Thang 5/2008
Nghien cufu & Trao doi
So' Heu tren bang 2 ciia toa do dif bao bao so' 2 dd'i vdi sd do BMJ va KF ciia ETA difdc the hien tren ban do ciia hinh 5, va hinh 6 tifdng i^ng.
Hinh 5. Quy dgo dUbdo 168h (7 ngdy) dot vdi cdn bdo sd 2 (td khi con Id ATND) cua sddo BMJ (ETA) td 06z ngdy 01- 8 de'n 18z ngdy 07 - 8 -2007.
t&miM'^ «E '"^ "^ 1'™ "== ™ "'^ soo;l*M-iMS
So heu ve khoang each (tinh bang Km) tiJf tam bao difbao cua cac sd do va tam bao thifc difdc tinh toan va so sanh trong bang 3.
Bang 3. Khoang cdch tii tdm bdo thiic de'n tdm bdo dii bdo cho bdi cdc sddo BMJ (ETA) vd KF (ETA) cung vdi cdc gid tri trung binh ddi vdi dUbdo 3 ngdy ddu vd 7 ngdy cho bdo sd'2.
S6' TT 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Tholi gian di^
bao 12h 18 24 30 36 42 48 54 60 66 72 78 84 90 96 102 108 114
Khoang each tit vi trf thi^c d&'n vj tri dl? bao bdi K F (ETA) K m
98,5 72,6 157.4 244,5 334,7 348,4 304,0 232,3 267,3 245,9 182,2 195,1 255,2 398,6 365,0 355,3 314,2 289,1
Tap chi Khi tir<;^ng Thuy van * Thang 5/2008 17
Nghien cuTu & Trao dO'i
So*
TT 19 20 21 22 23 24 25 26 27 1 ^ 12 1 ^ 27
Thcfi gian d\f bao
120 126 132 138 144 150 156 162 168 Gia tri trung binh cho dif b i o
3 ngAy (feu Gia tri trung binh cho duf Mo
7 ngay
Khoang each tiJf vl t r i thiJc dSh vi tri drf bao bdi KF (ETA) Km
205,6 103,9 55,6 122,4 190,9 208,4 195,1 212,3 168,2 224
227
Cac ke't qua cua bang 3 difdc the hien bang nhan tha'y, trong tru'dng hdp cdn bao so' 2, hai dd thi tren hinh 7, vdi thdi ban d\i bao each sd do tinh toan dd'i lu\i BMJ va KF cho 2 dy nhau 12h. bao diln bie'n thdi tie't va sif di chuyen cua tam
Tif ke't qua tinh toan ciia bang 3 va hinh 7, bao khac biet nhau mot each rd ret.
Sai so K h o a n g e a c h Tam bao t h u c
Nei Ucn VonH - KF Boo Nr 2(2007) "0704"
- > Tom KF
Khi tinh trung binh 7 ngay, sd do KF (ETA) cho sai lech trung binh la khoang 227 km, nho nha't trong so' 2 sd do dem ra phan tich. Sd do BMJ td ra kem hdn khi ban dif bao keo dai de'n 7 ngay vdi sai lech trung binh len de'n 454 km.
Sd do KF the hien hdn ban so vdi sd do BMJ trong cung mot md hinh Idiu vifc la ETA. Dieu nay phii hdp vdi cac ke't qua nhan difdc trong cac nghien ciJu trifdc day [5], [6].
Dd'i vdi trung binh 3 ngay (72h), ca hai dif bao (BMJ va KF) deu cho sai so' chap nhan
Hinh 6. Do thi sai so^khoang cdch td tdm bdo thiic den tdm dii bdo cda sddo KF cho dii bdo 168 h cdch nhau 12h doi vdi cdn bdo so 2 (0704)
du'dc. Phan dif bao tu" 12h de'n khoang 36h, sd do BMJ td ra td't hdn so vdi KF, sau 36h de'n 72h va tham chi 168h sd do KF the hien difbao td't hdn so vdi BMJ. Khi thdi ban dif bao tang len de'n 7 ngay, sai so' ciia BMJ tang rat nhieu (gan gap 2 lan), trong khi sai sd'ciia KF (ETA) lai tang rat it. Dieu nay the hien ban chat vat ly ciia sd do KF la sd do "ddng khd'i" (mass flux) theo quan diem ly luan hien dai hdn, trong khi sd do BMJ la loai sd do "hieu chinh"
(adjustment) khdng trifc tie'p siJ dung md hinh
18 Tap chi Khi tiftfng Thuy van * Thang 5/2008
Nghien ciJu & Trao doi
/?.may ([4], [6] va [8]). Sif phat trien ciia XTND cd ifu the trdi ciia ddng van chuyen Jdid'i lifdng manh me theo phifdng thang diJng, vi vay sd do KF dap ifng td't hdn hien tu'dng vat ly nay trong md hinh so' tri.
4. Ke't luan va kie'n nghi
- Suf khac biet rd ret nhan du'dc khi so sanh dif bao ciia sd do tham so' hda dd'i lifu BMJ va KF trong ciing mot md hinh khu vifc ETA cho tha'y vai trd quan trong ciia sif lifa chon phu'dng phap tham so' hda cac qua trinh vat ly quy md nhd (nhu' dd'i lifu...). Qua day ciing neu bat sif can thie't nen dau tif diing miJc cho cac nghien ciJu ve tham sd' hda dd'i lifu trong cac md hinh sd'tri d Viet Nam.
- Gia tri sai so' trung binh 7 ngay kha td't (227 km) ciia sd do KF trong ETA gdi y cd the diing dif bao ciia sd do KF (ETA) khi thdi tiet
cd bao boat ddng tren Jdiu vifc Viet Nam. CQng qua day, nhan tha'y mot hu'dng nghien ciJu cd the mang lai Idi ich khoa hoc va thifc tien la nghien cii^i cai tie'n sd do Kain-Fritsch trong md hinh ETA.
- Hien nay nhu cau kinh te-xa hoi ve duf bao ATND va bao ngay cang cao, du" bao bao d Viet Nam da du'dc nang len tiJf 24h de'n 48h.
Mac dii vay, vdi dieu kien hien cd d Viet Nam, chiing ta cdn cd the xem xet de'n viec nang cao them thdi ban duf bao bao len de'n 72h. Dieu nay xua't phat tif nhan dinh rang ATND va bao cd quy md sy-nd'p, vdi sif phat trien hien nay ciia cac md hinh sd' tri toan cau (vi du GFS ciia NCEP...) va cac md hinh khu vifc dang chay d Viet Nam nhu": ETA, HRM, MM5 va RAMS thi kha nang du" bao trifdc 72h dd'i vdi mot thifc the khi quyen Idn nhu" bao la trong tam cd the hien thifc hda.
Tai li§u tham khao
7. A guide to The Workstation Eta Model", NCEP, NOAA, Washington, USA. Matthew P.; 2002.
2. The Step-Mountain Eta Coordinate Model: Further Developments of the Convection, Viscous Sublayer, and Turbulence Closure Schemes", Monthly Weather Review, Vol. 122, No 5, pp. 927-945. Janjic Z. (1994); Reprinted from American Meteorological Society by FHI (Yugoslavia) 3]. Further Studies of the parameterisation of the Influence of Cumulus Convection on Large-Scale
Flow", Journal of the Atmospheric Sciences, Vol. 31, pp. 1232-1240; Kuo H. L. 1974
4. A one-Dimensional Entrainment /Detrainment Plume Model and Its Application in Convective Parameterization", Journal of The Atmospheric Sciences, Vol. 47, No. 23, pp. 2784-2802; Kain J.
S and Fritsch J. M. ; 1990
5. Nghien ciiu so sanh hai so do tham sdhda ddi luu BMJ vd KF trong mo hinh ETA tren co sd ddnh gid du bdo quy dgo bdo XANGSANE (0615)"; Tuyen tap bdo cdo Hoi thdo KH Lan thiiX Vien KH KTTV &MT- thdng 3-2007. Dd Ngoc Thang -TTDB KTTV TLf.
6. Nghien ciiu cai tien so do tham so'hda ddi luu dp dung vdo mo hinh dif bdo thdi tie't sd'tri ETA cho Viet Nam". Ludn dn Tie'n si - Vien KH KTTV vd Moi trudng - Hd Noi; 2006. Do Ngoc Thdng - TTDB KTTV TLf
7. Chgy thii nghiem budc ddu mo hinh nghiep vu ETA95 trong dif bdo trUdng cdc yeu tdkhi tugng tgi khu vifc Nhiet ddi (cho trudng hop khdng co niii)", Tgp chi Khi tugng - Thiiy vdn, Hd Noi thdng V-1999, tr. 34-41; Dd Ngoc Thdng, Do Le Thuy.
8. Trdn Tdn Tie'n (2002), "Ddi luu khi quyen ", NXB DHQG, Hd Ngl.
