Hgi nghi Khoa hgc ky niem 35 ndm Vien Khoa hgc vd Cong nghe Viet Nam - Hd Ngi 102010
CONG NGHE GPS VA iTNG DUNG TRONG LINH VUC NGHIEN ClTU KHOA HOC TRAI DAT
GLOBAL POSITIONING SYSTEM AND ITS APPLICATION FOR THE EARTH'S SCIENCES
Le Huy Minh, Pham Xuan Thanh, Tran Thj Lan, Nguyen Chien ThSng, Nguyen Ha Thanh, Le Tru-o-ng Thanh
Vien Vit ly dia ciu
A8, 18 Hoing QuIe Viet, Ciu Giiy, Ha Ndi Email: [email protected]
Tom tat:
Bdi bdo trinh bdy nguyen ly sir dung cdng nghe GPS trong cdc nghien ciru dien ly, khi quyen vd dich chuyen kien tgo vd Trdi ddt vd mdt sd kit qud sir dung sd lieu cdc trgm GPS lien tuc tgi Hd Ngi, Hue vd thdnh phd Hd Chi Minh giai dogn 2005-2009 trong cdc huang nghien ciru ndy a Viet Nam. Ket qud nghien ciru chi ra rdng Viet Nam ndm a viing di thuang dien ly xich dgo, khu vuc phia Bdc ndm a viing dinh di thuang (ndng do dien tir cue dgi), phia Nam ndm a viing ddy di thuang (ndng do dien tir cue tieu). Ndng do dien tir quan sdt duryc tgi cdc trgm thay ddi tir ngdy ng sang ngdy kia vai chu ky ngdy dem ro ret, bien thien theo miia vai cue dgi a thdi ky phdn diem vd cue tieu cr thai ky miia ddng vd miia he, vd phu thudc vdo chu ky hogt dgng Mat Trai. Do tre thien dinh vd hdm luang hai nuac tdng cdng tdng ddi luu khi quyen tinh dugc tir sd lieu GPS the hien ro sir bien ddi theo thai gian vai cdc chu ky ngdy dem vd bien ddi theo miia phu thugc vi tri dia ly ciia cdc trgm. Ket qud tinh todn van tdc dich chuyen vd Trdi ddt tir cdc sd lieu GPS trong thai gian da neu cho thdy rdng cdc diem Hd Ndi, Hue vd Tp HCM dich chuyen tuyet ddi ve phia ddng nam vai cdc van tdc 35,4; 32,3 vd 24,1 mm/ndm mot cdch tuang irng trong he quy chieu ITRF2005. Tinh todn dich chuyen tuang ddi so vai khdi Sundaland cho thdy rdng cdc trgm Hd Ngi, Hue vd Tp HCM dich chuyen ve phia tdy nam van tdc khodng 8-12 mm/ndm vdi xu the quay theo chieu kim ddng hd. Cdc ket qud da chi ra khd ndng to lan ciia viec sir dung sd lieu cdc trgm GPS lien tuc trong viec nghien ciru cdc hien tuang vdt ly trong tdng dien ly vd tdng khi quyen, vd dich chuyen kien tgo vo Trdi Ddt a Viet Nam.
Abstract:
The applications of the GPS (Global Positioning System) for studying the ionosphere, the troposphere and the crustal motion and some scientific results from the Hanoi, Hue and Ho Chi Minh city continuous GPS data for the period
2005-2009 wewe presented. It was shown that Vietnam is under the equatorial ionisation anomaly (lEA), the Northen part in the crest and the Southern one in the hole. The ionospheric total electron content (TEC) calculated from GPS data at each station varies from day to another depending on the solar activity. In time series of the TEC, it can be seen clearly the diurnal variations, seasonal one with the maximum in the equinox and the minimum in the summer and the winter... The zenithal total delay and tropospheric integrated water vapour calculated from
GPS continuous data show also the diurnal and seasonal variations depending on the geographic position of the stations. The estimation of the Earth 's crust
Tiiu ban: Cdc khoa hgc vi trdi ddt ISBN: 978-604-913j;0J,6j^
determined from nearly 5 year data found that the horizontal velocity vectors in ITRF2005 in the Hanoi, Hue and Ho Chi Minh city stations are of 35,4, 32,2 and 24,1 mm/yr to the south-eastward, respectively. The relative velocity vectors with regard to the Sundaland block at these postions are of8-12mm/yr to the southwest and implicate the clockwide rotation of the Indochine block. The obtained results show the important possibilities for using the continuous GPS data to study the physical phenomena in the ionosphere and in the troposphere, and the tectonic
motion of the Earth's crust in Vietnam.
1. Mffdau
He thing djnh vi toin ciu (Global Positionning System - GPS) gom 24 ve tinh (hien tai sl ve tinh cdn sir dung dugc it hon) bay d do eao khoing 20.200 km trong 6 mat phang quT dao vdi do nghieng li 55° so vdi mat phing xich dao. Mdi ve tinh phit ra eic thdng tin vdi muc dich dinh vj tren hai sdng mang lien ket Li va L2 trong dii L. Hai tin sd mang fi va fj duge suy tir tin so eo bin fo=10,23MHz (f,=154fo=l 575,42MHz; f2=120fo= 1227,60MHz) [10]. Tin hieu truyen tir cac ve tinh eiia he thdng djnh vj toin ciu tdi mdt miy thu tren mat dit bj inh hudng ding ke bdi ting dien ly vi ting khi quyen (giy nen eii ggi li do tre dien ly va do tre ting khi quyen), vi eic inh hudng niy dugc eoi li cic ngudn nhieu vdi mye dich djnh vj. Tuy nhien, dya vio do tre dien ly ngudi ta ed the thu duge thdng tin ve ndng do dien tir tdng edng ting dien ly, mdt tham sd dien ly quan trong cd lien quan tdi cie qui trinh vit ly lien quan tdi tir trudng Trii dit vi boat ddng Mat Trdi [13,16,18,19]. Dua vio do tre khi quyen ngudi ta cd the dinh gii dugc him lugng hoi nude tdng cdng ting ddi lun khi quyen, mot tham sd quan trgng lien quan tdi eic hien tugng khi hiu ciia Trii Dit [2- 5,7,11,20,21,26,27]. Mdt khi cic inh hudng eua ting dien Iy vi ting khi quyen duge loai bd, tir cie sd lieu GPS trong mdt khoing thdi gian dii dii, ngudi ta cd the thu duge thdng tin ve van tdc djch ehuyen vd Trii Dit tai eic vj tri quan sit vdi do phin giii tdi ed mm [6,8,22,23].
Thyc te hien nay viec img dyng cdng nghe GPS cho ci ba ITnli vyc neu tren phit trien manh me d khip mgi noi tren the gidi. Trong khudn khd hgp tic giiia Vien Vit ly dja ciu, Vien Khoa hgc vi Cdng nghe Viet Nam vdi Trudng Dai hgc Rennes 1, Trudng Vien thdng qude gia Bretagne, Cdng hda Phip, ba tram thu tin hieu ve tinh GPS lien tyc dugc dit tai Hi Ndi, Hul va thinh phi Hd Chi Minh (Tp HCM) tir diu nim 2005 vi 2006 tdi nay [1,13,18-20].
Bai bio niy trinh biy mdt sd ket qui dinh gii biin dii theo thdi gian eiia nong do dien tir tdng cdng ting dien ly, do tri thien dinh vi him lugng hoi nude ting ddi luu khi quyin, djch chuyen kien tao vd Trii dit tai eic tram GPS neu tren, minh hga triln vgng img dung cdng nghe GPS lien tyc d Viet Nam.
2. So lieu va nguyen tac xir ly so lieu
Ba tram thu GPS lien tue dit tai Hi Ndi, Hul va Tp HCM Ii cic miy thu GPS loai GSV4004 (A vi B) vdi bing dien tir thu nhin tin hieu loai OEM4-G2, vdi hai kilu anten NOV503 (di vdi miy GSV4004A) vi NOV533 (di vdi miy GSV4004B). Tram Hi Ndi tir thing 4/2005 din 13/01/2006 dit miy GSV4004A, sau dd dit miy GSV4004B. Tram Hui dit miy GSV4004A, tram Tp HCM dit miy GSV4004B. Cie tham sd quan sit duoc eua cic miy thu GPS loai niy li: Cl, Ll, Dl, Sl, P2, L2, D2 vi S2. Trong do Cl vi P2 li cic khoing cich gii mi C/A vi ma Y, Ll va L2 la phep do pha, Dl vi D2 li eic tin so Doppler, Sl va S2 li cudng do tin hieu d cie tan so GPS f, va fj mdt cich tuong img. Cie sd lieu quan sit dugc ehuyen sang djnh dang RINEX. Khoing cich thdi gian thu nhin tin hieu d eic tram Hul va Tp HCM li 30 giiy, d tram Hi Ndi li 1 giiy nhung ehiing tdi sir dyng sd lieu liy mau lai vdi khoing cich 30 giiy.
Hgi nghi Khoa hgc ky niem 35 ndm Vien Khoa hgc vd Cong nghe Viet Nam - Hd Ngi 10/2010
Mdi trudng dien ly li mdi trudng tin xa, ky thuat GPS 2 tin sd cho phep loai bd inh hudng eiia ting dien ly vi viec tinh toin ndng do dien tir tdng cdng ting dien ly (Total electron content - TEC) tir sd lieu GPS dya tren cdng thiic [13,18]:
TEC ^
40,3 (p'2,-pl-Ab'-Ab^) (1)
trong dd fi vi f2 li hai tin sd GPS, p,'^ vi p'^^ li khoang each gii giOa ve tinh i va may thu j ddi vdi cac tan sd fi va fi, Ab' vi Abj lien quan tdi eic do lech do phin cimg ve tinh vi do phin cimg miy thu. TEC trong cdng thiic (1) li TEC nghieng dugc chuyin sang TEC theo phuong thing dimg tai diem cit ting dien ly theo edng thiic:
TECV = TEC.cos z vdi z - aresin R^ cos a
(2)
trong dd Re li bin kinh Trii dit (6371km), h,on la do cao ldp don dien ly thudng duge liy li 400km, a li gdc nhin ve tinh tai vj tri miy thu. Trong eic ket qui tinh toin chiing ta se ehi quan tim tdi TECV, do viy khi ndi TEC da ngy y li TEC thing dung. Tdng cic do lech do phin Cling ve tinh va phin cirng miy thu trong edng thirc (1) dugc tinh bing cich so sinh TEC tinh duge theo cdng thirc vdi TEC tinh tir cie md hinh toin ciu dugc tinh vdi khoing cich thdi gian li 2 filng [13,18]. TEC dugc tinh theo don vj TECU, 1 TECU = lO'^ dien tir/m . Tir TEC tinh dugc do tre dien ly (tinh bing m) vi dy ddi vdi tin sl fi theo edng thire:
40 3
d,^,„=-^TEC (3)
J\
Ting khi quyen (hay cu the hon li ting ddi luu khi quyen) khdng phii li mdi trudng tin xa ddi vdi eic sdng radio tdi cic tin sd cd 15 GHz, vi the do khiic xa la nhu nhau doi vdi ei hai tan sd. Anh hudng eiia ting khi quyen tdi viee truyen tin hieu ve tinh GPS duge dinh gii bdi dai lugng ggi li do tre tdng edng ting ddi lun dugc xie djnh theo cdng thiie [2-5]:
Ap = CT = W^\N'""ds (4)
trong dd e li van tdc anh sing trong chin khdng, x li do tre tinh bing don vj thdi gian vi N"^°'' la do khiic xa cua khi quyen trung hda. N'™'' cd the dugc chia thinh hai thinh phin:
^U-np ^^ln,p ^^irop ^^^
trong dd thinh phan khd N"/'' giy bdi thinh phin thiiy tTnh vi thinh phan udt N^"''' giy bdi thanh phin khdng thuy tTnh ciia khi quyen. Nhu vay do tre ting ddi lun duge viet la:
Ap = Ap^+Ap„, (6)
Do tre ting ddi lun phu thudc khoing cich truyen eua tin hieu radio qua ting khi quyen trung hda vi the phu thudc vio gdc nhin ve tinh a. De nhin manh sy phu thudc gdc nhin ve tinh ngudi ta viet:
Ap = /,(or)Ap>/,„(a)AA! (7)
trong dd fd vi fw li cac ham ve ddi vdi do tre khd vi do tre udt, ApJ vi Ap° la cac do tre khd va do tre udt d thien dinh mdt each tuong img. Mdt him ve ia. mdt md hinh toan hgc bilu thi
Tiiu han: Cdc khoa hgc ve trdi ddt
sy phu thuoc gdc nhin ve tinh eiia cic dg tri tuong iing, xip xi bic nhit bing cosec cua goc nhin \e tinh. De tinh toin do tre ting ddi km. trong cic phan mini xir ly sd lieu GPS nhu Gamit [9] hoac Bernese... ngudi ta dua vio md hinh do tre ban dau tii- md binh khi quyen chuin. cic him ve khd vi udt, tir quan sit GPS, phin mim su dung phuong phip binh phuang nhd nhit de dinh gii do tre ting ddi luu trong klioing thdi gian nhit djnh (thudng li 1 hoac 2 tilng). Tir do tre thu dugc, loai trir do tri thiiy tTnh tinh tir md hinh cd the thu dugc do tre udt vi tir dd thu dugc him lugng hoi nude tdng cdng.
Viec tinh toin vi tri tram thu GPS tai mdi thdi diem quan sit vi tien tdi danh gii dich chuyin kiln tao vd Trai dit tai vj tri may thu vdi do ehinh xie cd mm trong he quy chieu chuin gin vdi Trii dit ddi hdi nhirng xir ly kha phire tap bing eic phin mem neu tren. Vi du khi chay phin mim GAMIT, cin phii chuin bi cic tep sau diy: process.default (quy dinh mdi trudng chay phin mim, cic nguIn sd lieu ben trong va ben ngoii, cie tep qui dao ve tinh, ciu true cho lun trir kit qui), sites.default (bao him ten eic tram IGS vi cie tram dia phirong dugc sir dung vi cich thirc quin ly tii lieu tram), station.info (chiia thdng tin ve kieu miy thu vi anten, gii tri do eao ciia anten, thdi gian boat ddng...), Ifile (chira thdng tin ve tga do gin diing ciia tram), sestbl (thilt lip eic lya chgn thich hgp cho viee phin tieh). Ngoai ra ein phii cap nhit thdng tin Ijch thien vin ve tinh, eic md hinh trieu Mat Tring vi Mat Trdi, vj tri cue eung nhu he quy chieu sir dung tinh toin tga do tram [9].
3. Ket qua va thao luan
3.1. Bien ddi theo thdi gian ciia ndng dp dien tir tdng cpng tdng dien ly
Hinh 1 bilu thj tiln trinh ngiy dem ciia TEC ngay 30/03/2009 tai Hi Ndi, Hue va thinh phd Hd Chi Minh; tit ei eic ky hieu diu + li TEC tinh dugc theo tit ei cic ve tinh, duong lien net li TEC trung binh d timg thdi diem quan sit. Chiing ta thiy ring vio thdi gian ban ngiy TEC ldn hon vao thdi gian ban dem, TEC bit diu ting vio khoing 22hUT (05hLT) dat eye dai vio khoing 06-07hUT (13-14hLT), tir khoing 12hUT (19hLT) TEC giim nhanh vi dat eye tieu vao khoing 22hUT (05hLT). Bien do eye dai tai tram Hi Ndi li ldn nhit va bien do eye dai tai Tp HCM li nhd nhit. Hinh 2a li bin dd phin bd theo thdi gian vi vT do ciia TEC ngiy 30/03/2009 d khu vyc nude ta tir vT do khoing 04° den vT do khoing 27°. Tren bin dd phin bd niy ehiing ta thiy vio ban ngiy xuit hien mdt vimg dj thudng TEC ed eye dai d khoing 18-20°, eye tieu d viing xich dao tir (d khoing vT do 8°). Dj thudng niy dugc biet nhu li dj thudng dien ly xich dao [1,13,18,19], Viet Nam nim hoan toan trong viing dj thudng dien ly neu tren, diy la diem die biet ciia ciu tnic dien ly d nude ta. Sir dyng sd lieu GPS vi the cd the nghien cuu die trung ciu tnic ciia di thudng nay vi mdi quan he giiia di thudng dien ly xich dao vdi cie hien tugng vit ly lien quan tdi hoat ddng Mat trdi, boat ddng eiia tir quyen... Tren hinh 2b li bin dd phin bd thdi gian vT do eiia do tre dien ly ddi vdi tin sd fi sir dung trong edng nghe GPS. Do tre dien ly vio ban dem khoing dudi 2m, vio ban ngiy tir 2 m den tren 5m. d viing dinh di thudng do tre dien ly dat eye dai. Viee xiy dyng dugc cic bin do do tre dien ly theo thdi gian va vT do duge tien hinh hing ngiy tren co sd sd lieu 3 tram GPS lien tyc Hi Ndi, Hue vi Tp HCM dudi dang eic bin dd sd, do viy cic do dac trie dia diing edng nghe GPS mdt tin sd cd the sir dung chung de ning eao do chinh xie do dae vdi viec sir dung hieu img dien ly chinh xie hon tir sd lieu GPS d Viet Nam.
Hgi nghi Khoa hgc ky niem 35 ndm Vien Khoa hgc vd Cong nghe Viet Nam - Hd Ngi 10 2010
0 3 6 9 12 15 18 21 24 0 3 6 9 12 15 18 21 24 0 3 6 9 12 15 18 21 24
UT UT UT
Hinh 1. Biin thien TEC ngdy 30/03/2009 a) tgi Hd Ndi, b) tgi Hui vd c) tgi Tp HCM
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a) b)
Hinh 2. Ban do phdn bd a) TEC vd b) do tre dien ly theo thdi gian vd vT do thu duac tir sd lieu 3 trgm GPS a Viet Nam ngdy 30/03/2009.
Hinh 3 li bien thien TEC ngiy dem trung binh thing tai Hi Ndi, Hue va Tp HCM. Cd the thiy TEC bien ddi theo miia khi rd ret, eye dai vio thdi ky xuin phin (thing 4) vi thu phin (thing 10), eye tieu vio miia he (thing 7) va miia ddng (thing 1 hoac thing 12). Hinh 4 bieu dien bien thien theo thdi gian eiia eiia bien do eye dai ngiy dem TEC trung binh thing tai Hi Ndi, Hue, Tp HCM vi sd vet den mat trdi trung binh thing trong khoing thdi gian 2005- 2009. Tir 2005 den khoing thing 1/2009 sd vet den mat trdi trung binh thing giim din (Mat Trdi d pha di xudng) vi sau dd bit diu ting (Mat trdi chuyen sang pha di len), trong pha di xudng thi eye dai bien do ngiy dem TEC d xuin phin eao hon eye dai d thu phin, trong pha di len thi ngugc lai eye dai bien do ngiy dem d thu phin eao ban d xuin phin, nhu viy bien do ngiy dem TEC tai mdi tram bien thien theo miia rit rd ring v i phy thudc chit che vio sd vet den Mit trdi.
^ m ^ : : ^ i ^
-n--Hinh 3. Bien thien TEC ngdy dem trung binh thdng tgi Hd Ngi (trdi), tgi Hui (giua) vd
Tai TD HCM (nhai) tmncr nnm 7000
Tgi Tp HCM (phai) trong ndm 2009.
Tieu ban: Cdc khoa hgc ve trdi ddt ISBN: 978-604-913-0J6^
D U 111 UJ O
u
m t o
111 I -
0 3 6 9 12 3 6 9 12 3 6 9 12 3 6 9 12 3 6 9 12 2005 2006 2007 2008 2009
60
0 3 6 9 12 3 6 9 12 3 6 9 12 3 6 9 12 2005 2007 2008 2009
0 3 6 9 12 3 6 9 12 3 6 9 12 3 6 9 1 2 3 6 9 1 2 2005 2006 2007 2008 2009
2005 2006 2007 2008 2009 2010
Hinh 4. Bien thien theo thdi gian cua bien do cue dgi ngdy dem TEC trung binh thdng a) tgi Hd Ndi. b) tgi Hue. c) tgi Tp HCMvd sd vet den mat trai trung binh thdng 2005-2009.
Khi tin hieu ve tinh GPS truyen qua vimg dien ly cd nhieu loan mat do dien tir ed gradient mat do ldn tao nen nhung thing giing rit nhanh ve bien do va pha ciia tin hieu, hien tugng nay duge ggi li nhip nhiy dien ly. Cic miy thu GPS lien tyc duge dit tai Hi Ndi, Hue va Tp HCM dang boat ddng hien nay duge lip dit trong khudn khd hgp tic vdi Phip vdi mdt trong cie mye dich li theo ddi hien tugng nay d khu vyc Viet Nam. Cic ket qua nghien cim budc diu cho thiy nhip nhiy dien ly thudng xuit hien vio ban dem d khu vyc dinh di thudng dien ly xich dao. trong nim nhip nhiy dien ly xuit hien nhieu vio thdi ky phin diem, tin suit xuit hien nhap nliiy bien ddi theo boat tinh Mat Trdi. Nhiing tinh chit niy gin tuong ty vdi tinh chit eiia trudng tir vi bien thien cac tham sd dien ly d nude ta [16.17]. TEC ciing bien ddi rd ret trong thdi gian bao tir [14,19]. Nhu viy eic thdng tin vl ting dien ly thu duge tir eic so lieu GPS ed mdt mdi chit ehe vdi boat tinh Mat Trdi, boat tinh tir ciing nhu cie tham sd dien ly thu duge tir cae thim dd thing dung vi diy la chii de nghien cim cdn duge phit trien de tim hieu ky eing hon cic qua trinh vit ly trong ting dien ly, dy bio dien ly dip img nhu ciu ngay eing tang cua \ iee nghien cim vi sir dung khoang khdng vii try khdng chi d eic nude phit trien tren the gidi mi ca d Viet Nam.
Hgi nghi Khoa hgc ky niem 35 ndm Vien Khoa hgc vd Cong nghe Viet Nam - Hd Ngi 10/2010
Ngudi ta cdn thiy TEC lien quan tdi cac hien tugng xiy ra trong vd Trii dit nhu ddng dit [14] hoac sdng thin [15], nhiing hudng nghien ciru niy cdn chua duge dl cap tdi d Viet Nam vi eung li mdt trong nhirng ehii de cd the phit trien trong tuong lai.
3.2. Bien ddi theo thai gian ciia dp tre thien dinh vd hdm luang hai nirac tong cpng tdng ddi luu khi quyen
Sir dyng phin mem GAMIT vi cic sd lieu GPS ehiing tdi thu dugc chuoi sd lieu do tre thien dinh tdng cdng ZTD tinh bing mm trong khoing thdi gian 2005-2009 dugc trinh biy tren hinh 5. Do phin giii thdi gian eiia chuoi sd lieu li 1 tilng ddng hi. nhu viy moi ngiy tinh dugc 24 gii trj ZTD, moi gid mdt gii tri. Trong khoing thdi gian 2005-2009.'sd lieu eua cic tram Hi Ndi vi thinh phi Hd Chi Minh li tuong dii diy dii, sd lieu eiia tram Hul bi thilu gin 1 nim giira thing 5/2007 vi thing 5/2008. Dii khdng diy dii sl lieu d tram Hul, nhung ehiing ta thiy ZTD bien ddi theo chu ky nim khi rd ret. Trudc khi dk cap tdi vin dl ehu ky nam, chiing ta biy xem xet eic die trung biin dii ngiy dem trung binh eua do tre thien dinh tdng edng tai timg tram rieng biet.
2750 -p 2650
^ 2550 I- Q
N 2450 j- -^ - I - H-ANOI 2350
90 180 270 360 90 180 270 360 120 240 360 90 180 270 360 90 180 270 Ngay - 2005 Ngay - 2006 Nuny - 200" Nuny - 2008 Ng.iy - 200O
2750 1- -,
E E
360
I-O N
90 180 270 360 90 180 270 360 90 180 270 360 90 180 270 Ngay - 2(K)6 Ngay - 200" Ngay - 2008 Ngay - 2009
360
E E^
H Q N
2750 ^ 2650 2550 2450 2350
n ,- I - I T P H O CHI MINH
90 180 270 360 Ngav - 2005
90 180 270 360 Ngav - 2006
90 180 270 360 Niiav - 200"
90 180 270 360 Ngay - 2008
•\ I . . ^ . I 90 180 270 360 Naav - 2000
Hinh 5. ZTD tgi cdc trgm Hd Ndi, Hui vd Tp HCM giai dogn 2005-2009
De nghien eiin bien thien ngiy dem eiia ZDT, chiing tdi tiln hinh liy gii trj trung binh gid eiia toin bd chudi sd lieu quan sit trong khoing thdi gian 2005-2009 ddi vdi tram Hi Ndi vi Tp HCM vi 2006-2009 dii vdi tram Hul, kit qui dugc trinh biy tren hinh 6. Tir hinh 5 ehung ta cd the thiy do ldn ciia ZTD trung binh tai Ha Ndi li khoing 2562mm, tai Hul la 2590mm %i tai Tp HCM li klioang 2604mm. Nhu viy rd ring eing gin xich dao thi ZTD cd do ldn tuyet ddi eing ldn, tuy nhien bien do biin thien ngiy dem eiia ZTD d hinh 6 cho thiy a Hue li ldn nhit va o Hi Ndi la nlid nhit. Dao ddng ngiy dem trung binh tai mdi tram cd hai
Tiiu ban: Cdc khoa hgc ve trdi ddt ISBN: 978^604-913^0]^
eye dai vi hai eye tieu khi rd ring; eye dai thii nhit vio bull sing \ i o khoing 2bUT (9hLT) tai Hi Ndi. khoing 5hUT (12hLT) tai Hul va Tp HCM: eye dai thir hai vio ban dem khoing 17hUT (24hLT) tai Hi Ngi vi khoing 14hUT (21hLT) tai Hul va Tp HCM; cue dai thir hai CO bien do ldn ban eye dai thir nhit, die biet li d tram Hul va Tp HCM. De xem xet chi tiet hon ddng gdp eiia eic dao ddng ed ehu ky khie nhau trong tiln trinh ngiy dem trung binh, chiing tdi tiln hinh phan tich Fourier tdi n=4 chuoi sd lieu biin thien ZTD trung binh ngay dem (liy ZTD ngiy dem trir di gii tri trung binh ngiy). Ket qui xie djnh eic he sd tren dugc trinh bay trong bing 1 vi dugc bieu dien d hinh 6d. eic hii dilu hda n=l,2,3,4 tuong img vdi cic dao ddng chu ky 24 gid, 12 gid. 8 gid vi 6 gid mdt cich tuong irng. Tir bing 1 chiing ta ed thi thiy ring eac dao ddng cd ehu ky 24 gid vi 12 gid ddng vai trd quan trgng trong tien trinh ngiy dem cua ZTD. Tai Tp HCM va Hul he sd Cl ldn hon he so C2, trong khi tai Hi Ndi he sd C2 ldn hon he sl CL nhu thi tai Hul vi Tp HCM dao ddng ed chu ky 24 gid chiem uu thi. trong khi tai Hi Ndi dao ddng cd ehu ky 12 gid lai chiem uu the. Sy chenh lech ve pha (pi giira Ha Ndi vi Hul khi ldn khoing 124° giii-a Hul vi Tp HCM khoing 18°. Cic dao ddng CO chu ky 12 gid va 24 gid trong khi quyen tuong img vdi cic dao ddng trieu do kich ddng nhiet va trgng lyc tir Mat Trdi [11]. sy khie nhau ve cic dao ddng chu ky 24 gid vi 12 gid d biin thien ngiy dem trung binh eiia ZTD d tai 3 tram Ha Ndi, Hue va Tp HCM cho chiing ta thiy ring cic dao ddng trilu d vj tri nghien cim cd sy khie nhau rit rd ret, ZTD thu duge tir sl lieu GPS vi thi ed thi duge sir dung trong nghien cim ddng lyc ciia cie qui trinh vit ly trong khi quyin. Tren hinh 6d ehiing tdi trinh biy tien trinh ngiy dem trung binh ciia ip suit khi qu\in do dugc tai tram Phu Thuy (cich Hi Ngi 20km) trong khoing thdi gian 1999-2001.
Chiing ta ed the thiy ring mie dii chudi sd lieu khdng thu duge trong ciing khoing thdi gian, nhung bien thien ngay dem trung binh eiia ip do duge tai mat dit d tram Phu Thyy tuong quan rit tdt vdi bien thien ngiy dem trung binh ZTD tai Hi Ndi thu dugc tir sd lieu GPS, he sd tuong quan li 0,88. Chiing ta biet ring ZTD phy thudc vao mat do khi quyen, mi mat do ciia khi quyen lien quan chit che vdi ip suit, nhu viy thdng tin ve ZTD li rit ed y nghTa trong nghien cim ve trang thii khi quyen. vi cd the ehuyen ddi sang ip suit vdi do tin ciy eao.
Ngiy nay trudc tinh trang cd nhung thay ddi toin ciu ve klii hiu, thdng tin ve ting khi quyen thu duge tir sd lieu GPS li mdt ddng gdp quan trgng vi thyc te chiing cd the thu duge trong mgi dieu kien thdi tiet, ed the ddng gdp vio viee nghien cim khi hiu d mgi ty le, tir ty le toan ciu [26,27] tdi ty le dia phuong [2.4,21].
Bdng 1. Cdc hdi dieu hda cua bien thien ngdy dem trung binh ciia do tre thien dinh tdng cdng tgi Hd Ndi, Hue vd thdnh phd Hd Chi Minh
n 1 2 3 4
Ha Noi
Cn
1.91 2.35 0,26 0.13
(Pn
-38,71 -19,66 -64,14 -51.59
H
Cn
4.70 3,01 0.60 0.27
ue
(Pn
85.48 1,52 49,25 -11.24
Tp Ho Chi Minh
Cn
4.65 1.78 0,46 0.28
CPn
67,69 -1,14 -62,56 -28.12
Hgi nghi Khoa hgc ky niem 35 ndm \ 'ien Khoa hgc vd Cong nghe Viet Nam - Hd Ngi 10/2010
9 12 15 18 21 C i f l r - l T
Hinh 6. Tien trinh ngdy dem trung binh ciia ZTD a) tgi Hd Ndi, b) tgi Hui vd c) tgi Tp HCM.
d) Bien thien ngdy dem trung binh cua ZTD vd xdp xi bdng chudi Fourier tirang irng tgi ba trgm Hd Ndi (hinh thoi). Hue (hinh vudng), Tp HCM (hinh tam gidc) vd tiin trinh ngdy dem
trung binh cua dp sudt khi quyen giai dogn 1999-2001 tgi Hd Ndi (duang liin net) Nhu d tren di neu, tir ZTD tinh toin duge tir sl lieu GPS, sir dung md hinh ed thi tinh dugc do tre thien dinh thiiy tTnh (zenithal hydrostatic delay - ZHD), sau dd tinh do tri thien dinh udt ZWD bang hieu sd giiia ZTD vi ZHD vi tir dd ed thi chuyin dii sang him lugng hoi nude tdng cdng (integrated water vapour - IWV) ting dii Imi khi quyin. Vi ZHD biin dii it theo thdi gian trong ngiy do viy eic phin tieh tiln trinh ngiy dem eua ZTD d tren eung hoan toin dung ddi vdi IWV.
CM
E
"S) 80 60 40 20
90 180 270 360 90 180 270 360 90 180 270 360 90 180 270 360 90 180 270 360 Ngay - 2005 Ngay - 2006 Ngay - 2007 Ngay - 2008 Ngay - 2009
80 ; ; , ^ •
90 180 270 360 Ngay - 2006
90 180 270 360 Ngay - 2007
90 180 270 360 Ngay - 2008
90 180 270 360 Ngay - 2009
CM
E
"5) 80 60 40 20
90 180 270 360 90 180 270 360 90 180 270 360 90 180 270 360 90 180 270 360 Ngay - 2005 Ngay - 2006 Ngay - 2007 Ngay - 2008 Ngay - 2009
Hmh 7. Bien thien theo thai gian cua hdm lirgmg hai nuac trung binh ngdy tgi Hd Ngi, Hui vd Tp HCM thu duryc tir sd lieu GPS (duang mdu xanh) vd tir md hinh todn cdu (duang mdu do)
giai dogn 2005-2009
Dk dinh gii ket qui tinh toin IWV, hinh 7 bilu dien biin thien theo thdi gian cua IWV trung binh ngiy tinh duge tryc tilp tir sl lieu GPS (eic dudng mau xanh) vi him lugng nude trong khi quyen tir md hinh toin ciu diing sd lieu tii phin tich cua Trung tim Dy bio mdi trudng qude gia My - Phdng Nang lugng [12] (cic dudng miu dd) tinh d khu vyc \i tri
Tiiu ban: Cdc khoa hgc ve trdi ddt
cie tram Hi Ndi. Hul vi Tp HCM trong khoing thdi gian 2005-2009. Tuong ty trong [20] eo thi thiy biin ddi theo thdi gian eiia IWV tinh duge rit phii hgp vdi biin ddi theo thdi gian cua IWV tir md hinh toin ciu d ci ba tram, tuy nhien tai tram Ha Ndi sy chenh lech giua IWV tinh tir sl lieu GPS \ i tir md hinh toin ciu li ding kl. IWV biin ddi vdi chu ky nim khi rd ring, tai Ha Ndi eye dai vio thing 7, eye tieu vio thing 12 vi thing 1, tai Hue va Tp HCM IWV ciing eye dai vio miia he nhung dinh eye dai khdng rd ring nhu d Hi Ndi. Chdng ehat len dao ddng ehu ky nim la eic giao ddng cd chu ky nhd tir mdt vii ngiy tdi cd chyc ngiy, nhtmg dao ddng niy chic chin phii lien quan tdi nhiing bien ddi thdi tiet ed the quan sit dugc tir cie sl lieu khi tugng, diy la ehii dl cho nhiing nghien cim tiep. Nhirng ket qua so bd tririh biy d diy eung chi ra khi ning to ldn eiia viee su dyng sd li|u GPS lien tue trong viee nghien cim cie qui trinh khi hiu d khu vyc nude ta, mdt ehii dl van cdn chua ed dieu kien de phit trien.
3.3 Djch chuyin kiin tgo vd Trdi dat tai cdc tram GPS lien tuc a Viet Nam vd khu vuc Ddng Nam A
Sir dung sd lieu GPS lien tuc tai 3 tram cua Viet Nam vi sd lieu eua cic tram GPS len tue trong khu vyc Ddng Nam A vi thi gidi. kit qui tinh toin djch chuyen tuyet ddi vd Trii dit d khu vyc Ddng Nam A trong ITRF2005 dugc trinh biy trong bing 1 vi duge bieu dien tren hinh 8 (eic vector minh). Kit qui tinh toin djch chuyenjuong ddi ciia cie tram so vdi khdi Sundaland dugc trinh bay d bing 2 vi eung duge bilu dien tren hinh 8 (cie vector dim).
Vj tri eye Euler ciia khdi Sundaland li (49,0"^, -94.2"E) vi van tie gdc quay li 0,336'Vtrieu nim duge liy theo Simson va nnk [22]. Cie tram tir KUNM tdi BAKO nim trong khdi Nam Trung Hoa hoac khii Sundaland dang djch chuyin vl phia ddng nam, cic tram d phia Bac (KUNM, Hi Ndi vi Hul) djch chuyin nhanh hon vdi van tie 3,2-3,5cni/nim, eic tram d phia Nam (Tp HCM, NTUS, BAKO) dich chuyin chim hon vdi van lie 2,2-2,6em/nim. Tram PIMO d mang Philippine dang djch chuyin vl phia tiy bic vdi van tdc 3cni/nim, ket qua nay hoan toin phii hgp vdi xu the djch chuyen kien tao ming hien nay.
Bang 2. Cdc thdnh phdn tga do vd van tdc trong 1TRF2005 tinh duac tir sd lieu
Tram
KUNM Hi Ndi
Hul Tp HCM NTUS BAKO
cdc trgm GPS lien tuc a Viet Nam vd Ddng Nam A Toa do
Kinh do 102.797 105,800 107.593 106,560
103.680 106.849
VI do 25.030 21,047 16,459 10,849
1.346 -6.491
VE mm/nam
29,7 31,4 28,6 20,9
17,7 24,6
DLBPTB mm/nam
0,88 1,70 1,07 1,00
1,42 0,99
VN mm/nam
-19,1 -16,4 -15,1 -11,9 -13.0 -9.8
DLBPTB mm/nam
0.88 1,67 1,06 0,99
1,41 0.98 1.02
|V|
Mm/nam
35,3 35,4 32,3 24,1
21,9 26,5 30.1
Phuo'ng do 122.7 117.6 117.7 119,7
126.3 111.7
Hoi nghi Khoa hgc ky niem 35 ndm Viin Khoa hgc vd Cong nghe Viel Nam - Hd Ngi 102010
Bang 3. Dich chuyin tirang ddi cua cdc trgm GPS lien tuc a Viet Nam vd Ddng Nam A so vdi khdi Sundaland
Ten tram KUNM
Hi Ndi Hul TpHCM
NTUS BAKO
PIMO
VE (mm/nam) -6,1 -3,5 -5,2 -11.4 -11,3 -LO -61,8
VN (mm/nam) -11.9
-8,0 -5.9 -3.2 -5.4 -0,9 21.7
|V| (mm/nam) 13,3
8,7 7.9 11,8 12,5 1,4 65,5
Phuong vj (°) 207.1 203.6 221.3 254,4 244.6 228,9 289.4
Cic ket qui tinh toin van tdc tuong ddi so vdi khdi Sundaland cua chung tdi kha phii hgp vdi ket qui eiia Simson vi nnk (trir tram NTUS), vi du ddi vdi cic tram KUNM, BAKO vi PIMO li 13. 2 vi 64nim/niin mot cich tuong irng so vdi 13.3, 1,3 vi 65.5 mm/nim o bing 2. Sy phii hgp nhu viy li co sd de tin cay cie ket qui thu vdi sd lieu mdi eiia 3 tram GPS lien tuc ciia Viet Nam. Khi xem xet chudi thdi gian ciia cic tga do tram NTUS chung tdi thay cd mdt sy nhay bic vio thing 8/2007. dudng thing xip xi chudi sd lieu trude vi sau thdi diem nhiy bic ed he sd gdc khie nhau ding ke. die biet la d thinh phin Bac, do dd ehiing tdi ehi sir dung chudi thdi gian ciia cic tga do sau thdi diem nhiy bic niy d tram NTUS de tinh toin van tdc. Cic nghien cuu trude diy khdng sir dyng chudi sd lieu tdi thdi diem nhiy bic nay d tram NTUS vi the mi cd sy sai lech giua ket qui eiia chiing tdi vdi cie ket qui trong [22] ddi vdi tram niy. vi cic ket qui thu dugc trong tinh toin ciia ehiing tdi phii hgp hon vdi trudng van tdc kien tao hien nay. Cie tram Hue vi Tp HCM nam d klidi Ddng duong, ket qui d bing 2 vi hinh 8 cho ehiing ta thiy khdi Ddng Duong ed xu the quay theo chieu kim ddng hd rd ret, dieu niy li phii hgp \di quan diem kien tao ciia Taponnier [24]. Trong sd 4 tram d trong khdi Sundaland li Hul. Tp HCM, NTUS vi BABO thi chi ed tram BAKO cd van tdc tuong ddi so vdi klili Sundaland li nhd khdng ding ke. 3 tram cdn lai ed van tdc tir 8-12mni/nam, dieu niy CO the cho thiy bien dang trong ndi khdi Sundaland la ding ke vdi cae sd lieu mdi a Hi Ndi.
Hue vi Tp HCM. Sy thay ddi rd ret ciia trudng \ i n tdc tuong ddi so vdi klidi Sundaland d ba vj tri Hi Ndi. Hue vi Tp HCM cung chi rd sy cin thiet cua viee dit them cac tram GPS lien tuc d Viet Nam de ed the lim sing to vin de niy.
Ngiy nay viee do dae djch chuyen vd Trii dit bing phuong phip GPS. trong ky thuat vien thim ngudi ta cdn sir dyng mdt sd phuong phip trie dja klidng gian khie: phuong phip giao thoa khoing cich rit xa (Very Long Baseline Interferometry - VLBl), he thdng Doppler.
phirong phip giao thoa anh radar (Interferometrie Synthetic Aperture Radar - INSAR),... mdi phirong phip ed nguyen ly lim viec rieng vi duge sir dung vdi mye dich khie nhau. Phuong phap VLBl li ky thuat giao thoa thien vin diing trong thien vin radio, do dac khoing cich tir cic diem tren mat dit tdi eic ngudn d khoing cich rit xa (vi du cic quasars), dua vao sy chenh lech ve thdi gian tdi ciia sdng radio tai cic diem cd the tinh dugc khoing cich giira chiing vdi do chinh xie eo mm, phuong phip ed the duge sii' dung khi xie dinh dich chuyen ciia cic mang kien tao. He thdng Doppler DORIS li mdt he thing ciia Phip gdm khoang 60
Tieu han: Cdc khoa hoc ve trdi ddt ISBN: 978-604-913-026i8_
tram phan bd tuong ddi ddng deu tren toin ciu. he thing eiinc dya tren viee do dac khoang cich tir cic tram tdi cie ve tinh ciia he thdng (TOPEX/Poseidon \ i Jacon). Do ehinh xac ciia eic do dae khoang cich vdi muc dich dinh \j diing he thong niy thip hon so vdi he thdng GPS. tuy nhien eic do dae niy cung duge diing trong he quy chilu chuin qude te. Phuong phip INSAR thudng dugc sir dung xie djnh djch chuyin xiy ra do ddng dit \ di viec sir dyng phuang phip giao thoa cic inh radar tai viing chin tim ddng dit trudc va sau khi xiy ra ddng dit. phuang phip ni\- cho phep xie djnh khi ehinh xie djch trugt xiy ra do dgng dit tren doan dirt gay nhit dinh. cd the xiy dyng md hinh ca ciu chin tieu ddng dit. mdt thdng tin quan trgng trong nghien cim kien tao vd Trii dit. Phuong phip INSAR chua dugc sir dung rdng rai d Viet Nam trong cic nghien cim djch chuyen vd Trii dit do ddng dit. chii yeu do nhiing dich chuyen lien quan tdi ddng dit d Viet Nam trong thdi gian gin diy tuong ddi nhd, trin ddng dit ldn nhu ddng dit Tuin Giao nim 1983 khdng the ed inh radar d khu vyc Viet Nam d thdi diem niy de nghien cim. 0 nhieu noi tren the gidi ngudi ta da sir dung phirong phap INSAR trong viee nghien cim vi theo ddi hien tugng trugt Id dit. tuy nhien d Viet Nam do chua cd duge eo sd dii: lieu inh radar phong phii do viy phuong phip eung chua dugc irng dung rdng rai, diy li mdt trong nhirng hudng cd the phit trien manh trong tuong lai trong cac nghien cim ve mdi trudng.
30
100 105 110
Kinli do dia Iv
115 120 125
Hiiih 8. Dich chuyen tuyet doi (vector manh) vd dich chuyen tirang doi so vai cue Euler ciia khdi Sundaland (cdc vector ddm) cua cdc trgm lid Ngi. Hui. thdnh phd Hd Chi Minh vd cdc
trgm IGS trong khu vuc Ddng Nam A.
4. Ket luan
- Ket qui tinh toin ndng do dien tir tdng cdng ting dien ly tir sd lieu ba tram GPS lien tuc o Ha Ndi. Hue \ a Tp Hd Chi Minh lim sing to cau true cua dj thudng dien ly xich dao d Viet Nam. khu \yc phia Bic d viing dinh di thudng. khu \yc phia Nam nim d viing diy dj
Hgi nghi Khoa hgc ky niem 35 ndm I 'ien Khoa hgc vd Cong nghe Viet Nam - Hd Ngi 10 2010
ddi theo miia vi theo boat tinh Mat Trdi li eo sd khoa hgc tin ciy cho viee phit trien cic nghien cim ting dien ly tir sd lieu GPS vi eic qui trinh vit ly lien quan tdi boat ddng Mat trdi vi tir quyen Trii dit d viing xich dao Viet Nam.
- Do tre thien dinh vi him lugng hoi nude tdng edng ting ddi lun khi quyen thu dugc tir sd lieu ba tram GPS lien tuc d Hi Ndi, Hue vi Tp HCM cho thiy ring tien trinh ngiy dem ciia chiing tai mdi tram cd nhirng die diem rieng phin inh dieu kien khi hiu khu vyc tram.
- Cic dinh gii van tdc djch ehuyen tir sd lieu GPS lien tyc ed do tin ciy rit cao do cd dugc chudi sd lieu lien tue hing ngiy ve bien thien tga do. Djch chuyen kien tao vd Trii dit thu duge tir sd lieu GPS lien tue tai eic tram Hi Ndi, Hue vi Tp HCM cho thiy cie vj tri niy dang djch chuyen tuyet ddi ve phia ddng nam vdi cic van tdc tuong img li 35,4, 32,3 vi 24,1 mm/nam. So vdi khdi Sundaland, cie tram Hi Ndi, Hue vi Tp HCM djch chuyen tuong ddi ve phia tiy nam vdi van tdc bing 8.7, 7,9 vi 12,5 mm/nim vi khdi Ddng duong dang quay theo chieu kim ddng hd. Viee ting cudng cic tram ghi GPS lien tyc d Viet Nam li rit ein thiet, se cho phep hieu biet ehi tiet ve chuyen ddng quay niy ciia khdi Ddng Duong ciing nhu djch ehuyen tren dirt gay ldn d pham vi khu vyc nhu dirt gay Sdng Hdng se cho phep dinh gii chinh xie dieu kien kien tao ehi phdi toin bd cic qui trinh dja chit d nude ta.
- Nhirng ket qui thu duge d diy minh hga khi ning to ldn eiia viee sir dung edng nghe GPS trong cic nghien ciru irng dyng trong ITnh vyc eic khoa hgc Trii dit.
Loi cam o-n:
Bii bio duge hoan thinh vdi sy trg giiip kinh phi ciia de tii edng nghe vii try "Ung dung cdng nghe vii try de nghien cim dinh gii inh hudng ciia ting dien ly vi ting khi quyen tdi do ehinh xie khi sir dung tin hieu ve tinh d khu vyc Viet Nam"; eic de tii nghien cim eo bin "Sir dung sd lieu GPS lien tyc d Viet Nam vi Ddng Nam A nghien cim ndng do dien tir tdng cdng ting dien ly vi mdi lien quan vdi bien thien tir trudng Trii dit, dinh gia ham lugng hoi nude tdng edng ting ddi lun vi djch chuyen vd Trii dit d eic diem quan sit tai Viet Nam" vi "Nghien cim khi ning dy bio ngiy bit diu gid miia miia he - miia mua tren khu vuc Nam Bd".
TAI LIEU THAM KHAO
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Doerlinger, "'GPS monitoring of the tropospheric water vapor distribution and
Tieu ban: Cdc khoa hgc vi irdi ddt ISBN: 978-604-9[3
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