U'NG DUNG D 0 LIEU V I I N THAM RADAR TRONG XAC DINH SINH KHOI LOP PHU Rl/NG
TAI VIET NAM
ThS. T R A N T U A N NGOC KS. NGUYEN THANH NGA
Cue Vien Theim QuSc gia
Tom tat:
Biin doi khihiu dang diin biin phire tap vi inh huang ngay cang ton din moi mat kinh te, xa hdi cOa ioii ngirai. Di giim nhe biin dii khi hiu thi viec bao tin vi phit trien rimg CO y nghTa hit suv to ton. Di co thi bio ton vi phit thin rimg thi cic so lieu ve rimg trong do CO sinh khoi rimg cd y nghTa hit sire quan trong. Trong bai bio niy tic gia giai thieu phtrang phap tinh sinh khii rimg tren mat dit dira tren gia tri tin xa nguac tren inh radar.
Kit qui thir nghiem tinh sinh khii rimg tai tinh Hoa Blnh li khi quan chimg to day la phuong phip rat cd tiim ning trong tinh sinh khoi rimg tai Viet Nam.
d i y dii ve rirng l i r i t quan trpng d l cd the quan ly v i phit triin rirng mpt cich hipu qua [1]. Khflng ehi ed FAO quan t i m den eac sd lieu ve ripng, Cflng upc khung cua Lien hiep qgdc v l biin ddi khi hgu (FCCC) d l c i p d i n t i m quan trpng eua rirng v i hit sue quan tam d i n sd lipu v l ripng die bipt l i sinh khdi rirng, sd lipg lien quan true tiep d i n ham lupng c i c bon chiia treng rtpng[31.
Dpi vcri nydc ta, rirng cc vai trp h i t sire quan trpng trpng d n g cupc phit triin kinh t l xa hpi v i bac ve mfli tryd'ng. Thee tinh tpin chinh thdng thi n>ng deng gpp trye tilp v i n 1 % GDP qudc gia, nhyng dilu quan trpng hpn, rirng l i noi sinh sdng eua 25 trieu ngyfl'i vol nhilu ngyo'i thupe ddng bio d i n tpc it ngypi [4]. D l quin ly, bio ve v i phit trien rirng, nyo'c ta tiin hinh dilu tra danh g i i rtrng theo chu ky n i m n i m [4].
Viec dilu trg, dinh g i i ripng thep chu ky 5 n i m v i n chya thoa man nhu d u ciia c i e n h i quan ly, do thdi gian dilu tra k h i d i i nen eo sy sai lech gitpa b i o c i o vpi tinh hinh thyc t l eiia hien trang rtrng do vigc khai thic v i phit trien rtrng trong thdi gian dien ra dilu tra nhlt la vd'i rtrng trdng, ddi 1. Oat van de
Ljch sip phit trien cua Icai ngud'i g i n liln vo'i rirng v i sip dgng rirng. Rirng l i nggdn cgng d p nggyen lieg thfl cho x i y dyng, giao thflng, l i ngudn thyc pham eho con ngud'i va khi bj chgt p h i d i t rirng trp thinh t i i nguyen dat oho canh t i c nflng nghiep v i chp phit trien dd thj [1]. Rirng ngiy nay dang bj suy giam, vipe suy thoii n>ng v i chgt p h i rifng keo theo nhieu hp Igy cho eon ngud'i v i sy phit trien ben vung cua xa hpi loai ngypi. Chgt p h i ripng khflng chi l i mpt trpng eac t i e nhin ehinh g i y ra hien typng ndng len eua trii d i t thong qua tang khi thai nhi kinh trong khi quyin m i cdn l i m i n h hudng nghiim trpng d i n chu trinh tuin hcan cua nude, tang t i n xuit cgng nhy cydng dp lu lyt, suy kiet t i n g tru nude, l i m thoii hda d i t va d i n d i n sy tuyet chung cua mOt sd Ioii thye v i t va dpng vgt cd mci trtpd'ng sdng l i rirng [2].
Vdi t i m qggn trpng cga njng thi viec b i o v i rtrng dang l i v i n d l h i t sO'c d p thilt tren t h i gidi. To chirc Nflng Luong Liin hpp qgdc (FAO) chp ring thflng lin chinh x i c v i
TAP CHl KHOA HOC BO DAC VA B A N B 6 S 6 19-3/2014
Trao doi - Y kiih^
tugng thudng duge thu hogeh sau khi trong tu 5 d i n 7 ndm. Tuy nhidn, de nang cao t i n xuit diiu tra, danh gia hien trgng rirng Id v i n dd hit sue khd khan khi SLP dung du lieu viin tham quang hpe, logi dtf lieu ma vide chup anh phu thudc vao diiu kien thdi tiit.
De khae phuc hgn c h i v i ngudn du lieu trong didu tra danh gid rung, hien nay trdn t h i gidi da cd nhiiu nghidn cuu ung dtp lieu vidn tham sidu cao t i n hay cdn gpi la viin tham radar [5-6]. Du lieu vidn thdm radar ed Igi the so vdi vien tham quang hpe dd Id viec chyp dnh khdng phu thudc vao diiu kidn thdi tidt ndn ed kha nang chup dnh cho didn tieh Idn trong thdi gian ngan. Ben egnh do, viec xac djnh trye tiip thdng sd sinh khdi ripng thdng qua anh radar cung la mdt trong edc Igi the so vdi su dyng du lieu vidn thdm quang hpc.
ifng dung dir lieu FRADAR trong xae djnh sinh khdi rung tuy khdng phai la v i n dd mdi ddi vdi t h i gidi, tuy nhien, cac nghien cuu tren t h i gidi cho d i n nay tap trung chu ydu vdo rung phia bac (boreal forest) vdi chung loai thdng. Han nua, dp chfnh xac xac dinh sinh khdi rung bang dtp lieu anh RADAR phy thudc rat nhiiu vdo cdc ydu td nhu trl>
lugng rung, dac diim sinh thai rung, cdc diiu kien mdi trudng [7-8]. Do vay, de dp dung cdng nghd nay cho viec xdc djnh sinh khdi rung d Viet Nam c i n cd eae nghien cuu ve ca sd khoa hpc, phuang phap lugn cDng nhu tiin hanh thu nghidm de kiem Chung. Chi tren n i n tang nhu vay thi mdi cd the dua ra dugc cae k i t luat xae dang v i kha nang ung dyng cua cdng nghd trong diiu kidn cy the d Viet Nam.
2. Tong quan ung dung vien tham trong xac djnh sinh khdi Idp phu rung tren the gidi
TLP nhung nam 90 cua thd ky trude, nhidu cdng trinh nghidn cuu khoa hpc da dugc cdng bd chipng td tidm nang eua vidn tham radar trong viec xdc djnh sinh khdi tren
mat dat cua Idp phu rung. Vdi mdl quan tam ngdy edng cao cua xd hdi den thdng tin v i sinh khdi m-ng thi viec ung dung du lipu viin thdm radar trong xac djnh sinh khdi rirng tren mat d i t da va dang duge edc nhd khoa hpc nghien cuu va phat trien manh me trong thdi gian g i n day [9-12].
Ddi vdi cac ung dung vd thdnh lap ban dd sinh khdi rung, viec khai thdc ngudn^dO"
lieu radar eho tdi nay dugc thuc hidn bang hai phuang phap chfnh dd Id phuang phap trye tiep vd gian tiip [13]. Phuang phap trye tiip thidt lap mdi quan he giiia sinh khoi va tin hidu radar phan hdi trdn ca sd cwdng do tin xa ngwac (backscatter) hogc he s6 twang quan (coherence). Trong khi do, phuang phdp gidn tiip udc tinh sinh khoi dua trdn vide su dyng tham sd chiiu cao cay k i t hgp vdi vide su dung phugng trinh sinh trudng.
b. Phuxyng phip w&c tinh sinh khdi diea tren cwang do tan xa
Tu nhtpng nam d i u cua thap ky 1990, mdi quan he giu'a tdn xg ngugc cua song sieu cao t i n va tdng sinh khdi trdn mat dat da dugc nghien ciru mdt cdch rpng khap tgi nhieu khu vuc thu nghiem khdc nhau.
Phuang phap ndy dya tren ca sd vat ly do la sdng radar vdi budc sdng dai cd khd nang xuyen vao sau trong tdn Id va tuang tac vdi cdc thdnh phin eua cay nhu la, cudng canh va than cay. Khi tuang tde vdi cac thanh phin khde nhau cua cay vdi hang sd didn mdi tuang ddi khdc nhau se Idm thay ddi thudc tinh cua tia phan hdi ve cudng 66 va phan cue, nhD'ng thay ddi ndy tuang quan vdi thudc tfnh cua cay hay ndi cu the han Id tia phan hdi mang thdng tin ve sinh khdi cua eay nhd dd cd t h i tinh dugc sinh khdi cua Idp phu thue vat tren mat dit [14].
b. Phwang phip w&c tinh sinh khoi dya tren anh twang quan
Phuang phdp nay su dung gid trj tuong
TAP CHi KHOA HOC DO DAC VA B A N D6 SO 19-3/2014
quan giua hai dnh SAR dugc thu nhdn each nhau mdt khodng thdi gian ngdn su dyng ky thu$t giao thoa. Viec tinh toan sinh khdi tren mat d i t Idp phu ripng dua tren gia thiet, thue v|t vdi sinh khdi Idn cd sy dn djnh cao vd it bj tdc dOng cua mdi trudng (gid, mua) ndn gid trj tuang quan cao tren anh hgn so vdi thye vat ed sinh khdi thap han. Nghien euu sinh khdi tren mat d i t cua Idp phii rung su dung gia trj tuong quan cda cap dnh radar dugc thye hidn nd rd vdo dau nhirng ndm 2000 khi vd tinh ERS1/2 eua ESA duge phong len cho kha nang chyp dnh theo cdu hinh Tandem vd da cd nhung thanh tuu nhit djnh ddi vdi rirng phuang bde, cay hp thdng. Nhidu nghien cuu da chdng td, sir dung trj tuong quan cd the nghien cuu sinh khdi tdi 300 t/ha [15-16].
c. Phwang phap wac tinh sinh khoi dwa trdn tri do pha
Ky thuat InSAR dua trdn vide khai thae van giao thoa eua hai sdng didn tu trudng de udc tinh dd cao cua tam pha tan xg. Vj tri cua tdm pha tdn xg phy thudc vdo cau true eCia tham thyc vat, eae ca e h i tan xg va tinh chit cua bp cam. Ddi vdi khu vyc cd
thdm thyc vdt rung, tam pha tan xg Id tdng hgp cua t i t cd cdc tin hieu phan hdi tu mdt tap hgp Idn cde ddi tugng tan xa bao gdm la, canh, than cay va mat d i t tren didn tich dugc xde ^ n h bdi kich thudc mpt phan t u anh. Tdm phat xa thudng quy djnh bdi cdc ddi tugng tuang tdc manh nhit vdi song radar vd phu thudc vao t i n sd, sy phdn eye, gdc tdi, cung nhu dd ddy eua tdn vd mat dd rung. Ky thuat giao thoa cd the dugc dung d i udc tinh chiiu cao tdn rung do tri do pha giao thoa lidn quan den tam tan xa, ma neu lya chpn ddi t i n vd phan eye mpt each thich hgp, se bao gdm ca dp eao dja hinh va chieu cao cua tan rung.
d. Lwa chon phwang phap
Bang 1 eho thiy viec tinh sinh khdi rung tren mat d i t su dyng tri do pha va gid trj tuang quan eua edc ednh dnh la tuang ddi tuang ddng do thue ehit ca hai phuang phdp nay d i u su dyng cdng nghd radar giao thoa. Be cd cap anh cd gid trj tuang quan eao, anh phdi dugc chyp vdi khdc bipt v i thdi gian d i n tdi thieu, va thdng sd quy dgo ve tinh cd sy tuong ddng hit sue chat che gitpa hai l i n chup.
Bing 1: So sanh phwang phap xic djnh sinh khoi bing dw lieu radar
k i t qua Ngudng bao hda (kenh L)
Thu thdp d d lieu Yeu c i u quy dao
Nhieu pha Oieu kidn cung c i p d u lipu
Dja hinh S y djch chuyen cua dja hinh
D i i u kipn thdi tiet Khi quyen
Phu'O'ng phdp Gia trj tan xa
150 t/ha D o n Binh thu'dng Khong phu thupe
Khong han che Phy thuoc It phu thugc It phu thugc It phy thugc
He so tirvng quan 200 t/ha Lap theo chu ky
Chinh xac cao Phu thuoc
Han che Phu thuoc Phu thuoc Phu thugc Phy thugc
Trj d o pha 300 t/ha Lap theo chu ky
Chinh xac cao Phu thugc
Han che Phu thugc Phy thugc Phu thugc Phy thugc
TAP CHl KHOA HOC BO DAC VA BAN B6 SO 19-3/2014
Trao doi - Y kien.
Trpng khi dp, phyong phap sir dung tri tan xg ciia i n h cfl c i c yeu d u thugn t i i n hpn r i t nhieu eho ngydi sip dgng. Tri t i n xa tren i n h cOng phu thupe khong nhilu v i o dieu kien thdi tiit nen co t h i thu thgp anh d l ding, ngoii ra viec eung d p anh eOng khflng cfl b i t ky han e h i nao.
D i i u b i t lpi nhlt eua phyong phip n i y so vol hai phypng phip efln lai la ngypng b i o hda eua g i i tri tan xg vpi sinh khdi rirng nhp hpn. Tuy nhien vol sinh khdi rirng tren mat dat khflng Ipn cug Viet Nam (70 m'/ha sc vd'i 110 m /ha) thi b i t Ipi n i y cung khflng anh hypng nhilu d i n h i u h i t dien tieh rirng ciia nude ta neu sip dgng phuong phip n i y d l x i c djnh sinh khdi rirng tren mat dit.
Nhu vgy, cc t h i thiy d l tinh sinh khdi rirng tren mat d i t d Viet Nam sir dgng g i i tri t i n xa ngupc tren anh radar cd nhieu uu
diem hpn so vdi sir dung tq tuong quan tren anh eung nhu tri do pha.
3. ThiFc nghiem tinh sinh khoi rifng tren mat dat tinh Hoa Binh.
„ . Dii' lieu S(> dung
Trpng thye nghiim nay sif dung 02 cinh anh ALOS PALSAR p ehe dd chgp strip mede. Bang 2 T h i hien c i e thong s6 kJ thuit eug dii' lieu ALOS PALSAR su' dgng.
(Xem bing 2)
De hdi qgy vdi g i i tri t i n xa ngupc trin i n h , 83 6 tieu chuin dupe sO' dgng trong eong t i c thir nghiem tinh sinh khdi tren m^t d i t ldp phii rirng tinh Hda Binh. Hinh 1 cho t h i y c i c 6 tieu chuan dupe bd tri trai khap tren toan tinh, tuy nhien phia dflng ciia tinh npi thuin tien giao thflng ed sd diem nhieu hpn. fXem hinh 1)
Bang 2: Thong s6 ky thuat cua anh ALOS PALSAR sif dung
TT 1 2
Ngay chup 20/06/2007 07/07/2007
Gdc chup 34.3°
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Hinh 1: Sa do cac d tieu chuan
TAP CHi KHOA HOC DO DAC VA B A N D 6 S6 19-3/2014
Trao doi - Y kien b) Hdi quy gii tri tan xa tren inh vol sinh khoi rimg tren mit dat
G i i tri t i n xa ngupc tren i n h tai vj tri tuong tpng vol 30 fl tiiu ehuan dupc su' dyng d l hdi quy vdi sinh khdi nj'ng t r i n mat dat sip dgng h i m da tuyin. Bing 3 t h i hien k i t q u i hdi qgy da tgyIn ddi vol g i i tq tan xg tren anh ALOS PALSAR va sinh khdi rirng tgi e i c fl t i i u ehuin do ngoai thyc dja.
Bing 3 cho thiy, viec hdi quy sip dgng tq do t i n xg ra hai phan eye HH v i HV eai thipn dang ke k i t qga hdi qgy vpi g i i tri x i c djnh R tang tip 0.808 ddi vdi viec sip dgng tri do t i n xg ngypc phan eye HH len 0.918 khi si>
dgng tri do tip e i hai phin cyc.
c) Tinh sinh khii
Sau khi hdi quy g i i tri t i n xa ngypc tren i n h v i g i i tri sinh khdi td'ng tren mat d i t fl
tiiu chuan, phypng trinh thu dupe sip dgng de tinh sinh khdi tren mat dat rirng tinh Hda Binh tip g i i tri t i n xa ngypc tren anh ALOS PALSAR nhy sau:
^ 205.392
(1) Trcng dd:
- B i i gia tri sinh khdi (tIn/ha);
- X (HV) l i tri t i n xa phin eye HV tren anh (Db);
- Y (HH) la tri t i n xa phin eye HH tren i n h (Db);
- i, j l i sd thip ty hing v i cot tren i n h . Hinh 2 t h i hien k i t q u i tinh sinh khdi rirng tren mat d i t sir dgng g i i tri tan xg tren anh radar sir dgng cong thipc 1.
Bang 3: Hoi quy da tuyin dii voi dir lieu ALOS PALSAR
Tri do sip dung P h i n c y c HH va HV
Phan c y c HV P h i n c y c HH
R2 0.918 0.847 0,808
F 151.739 165.434 117.461
F im h^n 0.000 0.000 0.000
Sai so chuan 17.339 23.274 26.136
Hinh 2: Ban do sinh khoi tren mit dit rimg tinh Hoa Binh
TAP CHl KHOA HOC 0 0 OAC VA B A N D 6 S 6 19-3/2014
D l d i n h g i i k i t q g i tinh sinh khdi, g i i tri sinh khdi rirng tren mat d i t ciia c i e d tieu chuin khflng sir dgng trong tinh t o i n hdi qgy dype SLP dgng d l so sinh vpi k i t qua tinh sinh khdi dya tren gia tri t i n xg tren i n h . Bing 3 so sanh g i i tri sinh khdi tren mat d i t tai vj tri c i e fl tieu chuan eo g i i tri sinh khdi Ipn hpn 15 tIn/ha. Bang chc k i t qua khic kha qugn vol sai sd trung phypng khcang 6.5 tin/ha. Ty le v l sai sfl tinh sinh khdi vdi sinh khdi ripng eo sai sfl dp lech ehuin l i khping 23%, hay nfli cich khic tinh sinh khdi cc t h i cho do chinh xae tdi 77%. (Xem bang 4)
4. Ket luan
K i t q u i tinh sinh khdi rirng tren mgt d i t tinh Hoa Binh sir dung i n h vien thajTi radar CO dp chinh xac cap vol sai sd trung phupng khpang 6.5 tin/ha vi,dfl lech ehuan n l u tinh theo ty le vdi sinh khdi rirng l i 23%.
K i t qua n i y chirng td, sir dung gia tri tan xg tren irih radar de tinh slnli khoi rirng tren mat dit l i r i t kha quan v i e d nhilu tiim nang d l sir dung tren thyc t l .
Tuy nhien rirng tinh Hda Binh chi dgi dien cho mpt trong nam loai sinh thil ru'ng d Viet Nam dd la rirng thudng xanh tren niii d i vfli, d n irng dung tinh sinh khdi sip dgng anh radar dpi vdi cac he sinh t h i l rirng khac.O
Tai Meg tham khao
[1]. FAO., State of the World's Forests, s.o.w. forest. Editor. 2012, FAO: ROME.
[2]. Mgsselman. R. C. and Fox. D. G., A Review of the Role of Temperate Forests in the Global C02 Balance., in Joumai of the Air and Waste Management Association.
2012, Taylor & Francis: London.
[3]. Framework Convention on Climate Change, Report of the Conference of the Parties on its fifteenth session, held in Copenhagen from 7 to 19 December 2009, in Framework Convention on Climate Change,, D. CP15.pdf, Editor. 2009, United Nation: Copenhagen.
[4]. Bp Nflng nghiep va Phit trien Nflng thfln. (2011) Sao cao tiin do nganh Lam nghiep 2006 - 2010.
[5]. Beaudpin, A., et al.. Retrieval of
Forest Biomass from SAR Data.
Intematipnal Jpumal pf Rempte Sensing, 1994. 15(14): p. 2777-2796.
[6]. Askne. J. and Santoro. M., Boreal forest sterm volum estimation from multi- temporal C-band Insar observation. 2008.
[7]. Agstine, J.M., B.G. Mackey, and K.P.
Van Niel, Estimating forest biomass using satellite radar: an exploratary study in a tern- prate Australia Eucaliptus forest For|st ecplpgy management, 2003. 176(1-3): p.
575-583.
[8]. Balzter, H., C S . Rowland, and P.
Saich, Forestry Canopy Height and Carbon Estimation at Monks Wood National Nature Reserve, UK, Using Dual-wavelength SAR Interferometry. Remote Sensing of Environment 2007. 108(3): p. 224-239.
[9]. Beagdpin, A., et al.. Retrieval of for- est Biomass form SAR data. International Journal of Remote Sensing, 1994. 15(14):
p. 2777-2796.
[10]. Rauste, TH., et al.. Radar-based Forest Biomass Estimation. International Journal of Rempte Sensing, 1994. 15(14):
p. 2797-2808.
[11]. Letpan, T, A. Beaudpin, and D.
Guyon, Relating forest biomass to SAR data. IEEE Transactions on Geoscienee and Remote Sensing, 1992. 30: p. 403-411.
[12]. Imhoff, M.L., et al., BioSar(TM): an inexpensive airborne VHP multlband SAR system for vegetation biomass measure- ment IEEE Trgnsgetions on Geoscienee and Remote Sensing, 2000. 38: p. 1458- 1462.
[13]. Kpch, B., Status and Future of Laser Scanning, SAR and Hyperspectral Remote Sensing Data for Forest Biomass Assessment ISPRS Joumai of Photogrammetry and Remote Sensing, 2010.65: p. 581-590.
[14]. Ulaby, F T , R.K. Mpore, and A.K.
Fung, Microwave Remote Sensing- Active and Passive. 1986, Dedham, MA: Artech House Inc.
[15]. Fransson, J.E., Stem volume esti- mation in boreal forests using ERS1/2 coherence and SPOT XS optical data.
International Joumai of Remote Sensing,
TAP CHl KHOA HOC DO DAC VA B A N DO S 6 19-3/2014
Trao doi - Y kienJ
Bang 4: So sinh sinh khoi tinh tCr anh vai sinh khoi d tieu chuin v&i sinh khdi rimg tr§n mat dit l&n han 15 tin/ha
T§n d i e m OTC 29 OTC 30 OTC 31 OTC 32 OTC 34 OTC_36 OTC_39 OTC 42 OTC 43 OTC 46 OTC 47 OTC 49 OTC 50 OTC 52 OTC 54 OTC 55 OTC 60 OTC 61 OTC 62 OTC 63 OTC 64 OTC 65 OTC 71 OTC 72 OTC 73 OTC 74 OTC 75 OTC 76 OTC 77 OTC 82 OTC 83 OTC 84 OTC 86 PR 05 MT PR 09 DR PP 10 BS PP 12 DL PP 19 LV PP 20 NL PP 21 TD DT 10 STDV
Tpa d o X 2314542 2317475 2317438 2316649 2314833 2312797 2301823 2311017 2314549 2305840 2301478 2291250 2290471 2275631 2276226 2274431 2285336 2283952 2292560 2294053 2293208 2285647 2291422 2291730 2291861 2292013 2301951 2302640 2302620 2302179 2302387 2298170 2300581 2277437 2309459 2277449 2273514 2274907 2280152 2288100 2311063
Tpa d p Y 537146 537838 537905 540480 545749 543995 542554 534491 535256 533434 537576 549359 549026 556650 557374 555700 554725 554172 544748 542678 540278 551163 546257 546488 544293 544053 556659 657641 557205 561779 562010 562570 563643 551385 499385 515412 535312 517195 511970 506955 516184
S i n h k h d i d o 17.700 26.700 27.920 49.640 24.480 30.120 20.580 28.960 32.660 26.650 23.300 56.070 18.100 24.020 24.110 38.680 21.290 44.170 18.800 26.670 55.900 17.000 45.080 18.100 65.110 36.140 45.720 34.420 20.430 21.830 27.840 24.850 23.940 80.000 61.000 58.000 48.330 128.000 34.000 160.000 2 1 7 0 0 0
Sinh k h o i t i n h 22.900 32.786 31.223 56.546 26.899 27.932 11.930 24.089 34.288 32.752 18.227 59 884 27.557 18.725 19.971 33.032 36.779 41.443 24.300 22.157 61.528 11 854 56.654 24.300 79.013 44.108 46.845 41.246 27.363 26.254 35.280 31.755 29.655 78.635 67.168 62.410 45.135 135 242 24.938 143 285 198 914 RMSE
Chenh GT 5.200 6.086 3.303 6.906 2.419 -2.188 -8.650
^ . 8 7 1 1.628 6.102 -5.073 3.814 9.457 -5.295 -4.139 -5.648 15.489 -2.727 5.500 -4.513 5.628 -5.146 11.574 6.200 13.903 7.968 1.125 6.826 6.933 4.424 7.440 6.905 5.715 -1.365 6.168 4.410 -3.195 7 242 -9.062 -16.715 -18.086 7.490 6.524
T y l e 29.379 22.795 11.830 13.913 9.881 -7.263 -42.029 -16.821 4.985 22.895 -21.771 6.802 52.249 -22.043 - 1 7 1 6 7 -14.603 72.751 -6.175 29.255 -16.922 10.067 -30.271 25.674 34.254 21.353 22.048 2.461 19.832 33.934 20.268 26.726 27.789 23.873 -1.706 10.111 7.604 -6.612 5.658 -26 653 -10 447 -8 335 23 2536
TAP CHi KHOA HOC OO OAC VA BAN B 6 S 6 19-3/2014
2001. 25: p. 2777-2791.
[16]. Le Toan, T , et al.. On the Relationship Between Radar Measurements and Forest Structure and
Biomass. Proceedings of the 3th Intemational Symposium on Retrieval of Bio- and Geo-physical Parameters from SAR data for Land Application, Sheffield, UK, 2001.0
Summary
Application of radar remote sensing data in determining the forest biomass in Vietnam MSc. Tran Tuan Ngoc, Eng. Nguyen Thanh Nga
Vietnam Remote Sensing Center
Climate change has severe impacted to human soeio-economie. Forest plays critical role in the wprks pf climate change reductien and mitigatipn. Tp prptect the fprests, the for- est investigatipn data including the forest bipmass is very impprtant. This paper intrpdgces the wcrks of fprest abeve grpund estimatipn using radar baeksrattering data. The experi- ment calculating fprest abeve grpund bipmass in Hpa Binh prpvinee has signifiegnt result with the RMSE ef 6.7 ton/ha, which improve that radar backscattering datg could be the pctentigl data for forest above biomass estimation in Vietnam.O
Ngiy nhan bii: 06/02/2014.
SO SANH LU'ONG HOI NlTdC (Tiip theo trang 28)
[7]. Ha-Taek KWON, (2007), "Comparison of Precipitable Water Derived from Ground- Based GPS Measurements with Radiosonde Observation over the Korean Peninsula", Journal of the Meteorological Society of Japan, Vol. 85, No. 6, pp. 733-746.
[8]. Paul Tregoning, (1998), "Accuracy of absolute precipitable water vapor estimates from GPS observations". Journal of Geophysical Research, Vol.103, No.D22, pp. 28,701- 28,710.0
Summary
Comparison of PWV values derived by GNSS and by radiosonde at Tan Son Hoa station, Hochimlnh City
MSc. Huynh Nguyen Dinh Quoc, Ho Chi Minh City University of Natural Resources and Environment
Assoc. Prof Dr Nguyen Ngoc Lau, Hochimlnh City University of Technology Precipitable water vapor (PWV) in the atmosphere Is essential for weather forecast.
Currently, correct determination of PWV is a big concern to those talking interest in hydrom- eteorology. In this paper, we present the algorithms for determining PWV and then com- pare between PWV derived from radiosonde observation data and PWV derived from GPS data at Tan Son Hoa Station, Ho Chi Minh City The deviations between the two PWV val- ues in this study, are less than 1.2mm. In addition, PWV values changed in accordance with changes of weather on the surveying days.O
Ngay nhan bii: 14/12/2013.
TAP CHl KHOA HOC DO OAC VA B A N O 6 SO 19-3/2014
