Interannual wave climate variability in the Taiwan Strait and its relationship to ENSO events*

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1 Journl of Ocenology nd Limnology Vol. o., P. -9, 8 Internnul wve climte vriility in the Tiwn Strit nd its reltionship to ESO events* OU Ynd ( 欧衍达 ), ZHAI Fngguo ( 翟方国 ) **, LI Peiling ( 李培良 ) Ocen University of Chin, Qingdo, Chin Received Oct. 9, 7; ccepted in principle Dec. 7, 7; ccepted for puliction Dec., 7 Chinese Society for Ocenology nd Limnology, Science Press nd Springer-Verlg GmH Germny, prt of Springer ture 8 Astrct This study investigted the internnul wve climte vriility in the Tiwn Strit (TS) nd its reltionship to the El iño-southern Oscilltion (ESO) phenomenon using high-resolution numericl wve model. The results showed the internnul vriility of significnt wve height (SWH) in the TS, which exhiits significnt sptil nd sesonl vritions, is typiclly weker thn the sesonl vriility. The stndrd devition of the internnul SWH nomly (SWHA) showed similr sptil vritions in the TS throughout the yer, eing lrgest in the middle of the strit nd decresing shorewrd, except in summer, when there ws no locl mximum in the middle of the TS. Further nlyses proved the internnul wve climte vriility in the TS is controlled predominntly y tropicl cyclone ctivities in summer nd y the northesterly monsoon winds in winter. Furthermore, the internnul SWHA in the TS ws found correlted highly negtively with the ESO phenomenon. This reltionship minly derives from tht during the northesterly monsoon sesons. During the northesterly monsoon sesons in El iño (L iñ) yers, the negtive (positive) SWHA in the TS derives from wekened (strengthened) northesterly monsoon winds induced y lower-tropospheric nomlous nticyclone (cyclone) over the western Pcific Ocen nd the South Chin Se. During the southwesterly monsoon seson in El iño (L iñ) yers, however, the SWH in the TS tends to increse (decrese) nomlously ecuse of intensified (wekened) TC ctivities over the western orth Pcific Ocen nd djcent ses. Keyword : significnt wve height (SWH); Tiwn Strit; internnul vriility; El iño-southern Oscilltion (ESO) ITRODUCTIO The Tiwn Strit (TS), locted etween minlnd Chin nd Tiwn Islnd, is nrrow chnnel tht connects the Est Chin Se (ECS) nd the South Chin Se (SCS) (Jn et l.,, ; Feng et l., ). It is dominted y the Est Asi monsoon system, with the se surfce wind flowing from the northest in winter nd from the southwest in summer (Jn et l., ; Guo et l., ). Becuse of the soclled nrrow pipe effect, the TS is n environment of very complex ocen dynmics (Zheng et l., ). Among others, surfce grvity wves re deemed to hve considerle impct oth on shipping security nd on the costl ecosystem nd its mngement (Ymguchi et l., ; Bromirski et l., ; Zheng et l., ; Zhou et l., ). However, few previous studies hve considered the sptiotemporl vritions nd ssocited dynmics of surfce grvity wves in this region. Bsed on stellite oservtions, Chen et l. () reported tht the TS is one of the regions with the lrgest wves in Chin s offshore wters nd the djcent ses. They lso demonstrted tht the significnt wve height (SWH) in the TS hs considerle sesonl vrition, eing lrgest in winter nd smllest in summer. Forced y the Est Asi monsoon system, surfce grvity wves in the TS re dominted y strong northesterly wves in winter, wheres they re ffected y reltively weker * Supported y the tionl turl Science Foundtion of Chin (os. 8, 7), the Shndong Provincil turl Science Foundtion (o. ZRDQ), nd the Shndong Provincil Key Reserch nd Development Progrm (o. ZDJS9A) **Corresponding uthor: gfzhi@ouc.edu.cn

2 o. OU et l.: Internnul wve climte vriility in TS Mzu Jinmen Dongjido Prts Penghu 8 E 7 9 E Fig. Bthymetry (unit: m) of () the entire computtion domin nd () the TS Red dshed lines represent the northern nd southern oundries of the TS. In (), the red dots denote uoy sttions. In (), only ocen regions shllower thn m re shown. southwesterly-southerly wves in summer (Chen et l., ; Guo et l., ). Moreover, the wve directions re more complex in summer thn in winter (Zhng et l., ). The SWH in the TS hs lso een proven to hve considerle internnul vrition sed on oth stellite oservtions (Chen et l., ) nd numericl simultions (Hwng et l., ; Chien et l., ). Using the sme stellite oservtions, Chen et l. () stted tht they found pronounced period of vriility of out five yers in SWH in the TS, which might correspond to the El iño-southern Oscilltion (ESO; Wng et l., ). Considerle internnul vriility of SWH in the TS hs lso een noted y Hwng et l. () nd y Chien et l. () following high-resolution numericl simultions. Mny questions remin to e resolved concerning the internnul wve climte vriility in the TS. First, even though Chien et l. () reported the internnul vriility of SWH t Longdong sttion, locted to the northwest of Tiwn Islnd, the sptiotemporl vritions of SWH over the entire TS remin lrgely unknown. Second, the underlying dynmics lso remin unknown. In winter, surfce grvity wves in the TS re forced y northesterly monsoon winds (Lin nd Fng, ); however, in summer, they re forced oth y southwesterly monsoon winds nd y frequent tropicl cyclone (TC) ctivities (Chng nd Chien, ; Chn, ). Therefore, the dynmics responsile for the internnul wve climte vriility in the TS might differ etween these two sesons. Finlly, lthough potentil reltionship of internnul wve climte vriility in the TS with the ESO phenomenon hs een proposed y previous studies (Chen et l., ; Hwng et l., ), the precise chrcteristics of the driving mechnisms remin uncler. The ojective of the current study ws to investigte the internnul wve climte vriility in the TS sed on high-resolution simultions using regionl ocen wve model. This reminder of the pper is rrnged s follows. In Section, the model setup, relevnt dt, nd methods dopted in the current study re descried in detil. In Section, the model outputs re vlidted ginst oservtions. The results otined nd the conclusions derived re presented in Section nd, respectively. MODEL, OBSERVATIO, AD METHOD. Wve model The present study used the third-genertion Simulting WAves ershore (SWA; Booij et l., 999) model version.9 to hindcst the historicl wve records in the western Pcific Ocen for the period from Jnury 979 to July. As shown in Fig., the computtionl domin (, E) covered the Chin ses (nmely, the Bohi Se, Yellow Se, ECS, nd SCS) nd prt of the western orth Pcific Ocen. The sptil nd temporl

3 J. OCEAOL. LIMOL., (), 8 Vol. Tle Buoy oservtions in the TS Buoy sttion Loction Wter depth (m) Se surfce wind speed SWH Dongjido 9.E, Jinmen 8. E, Mzu. E, Penghu 9. E, Prts 8.8 E, mens no dt. computtionl resolutions were.. nd h, respectively. The resolution of the spectrl domin ws defined s.. Hz, divided into nds. The directionl resolution ws set to. Defult schemes nd prmeter vlues were dopted for the key physicl processes in the wve model. An exponentil growth of wind input ws dopted using the expression of Komen et l. (98). Dissiption processes in the wve model included whitecpping, depth-induced reking, nd ottom friction. The formultion of Komen et l. (98) ws pplied for the whitecpping process with dissiption coefficient of. -. The formultion of Bttjes nd Jnssen (978) ws pplied for depth-induced wve reking. The proportionlity coefficient of the rte of dissiption nd the rtio of mximum individul wve height over depth were set to. nd.7, respectively. The empiricl model of JOSWAP from Hsselmnn et l. (97) ws pplied for ottom dissiption dopting friction coefficient vlues of.8 nd.7 m /s for swell conditions nd wind se conditions, respectively. A lumped trid pproximtion scheme (Eldeerky, 99) nd discrete interction pproximtion scheme (Hsselmnn et l., 98) were used for the trid nd qudruplet wve-wve interction processes, respectively. The thymetric dt used in the wve model were otined from the ETOPO thymetry dtse of the tionl Ocenic nd Atmospheric Administrtion/ tionl Geophysicl Dt Center, which cn e downloded vi glol/etopo.html. The horizontl resolution of the ETOPO dtse is ' '. The wve model ws forced with wind vectors t m ove the se surfce derived from the Europen Centre for Medium-Rnge Wether Forecsts Interim renlysis (ERA-I; Dee et l., ). The se surfce wind vectors re provided t UTC,,, nd 8 with sptil resolution of... In ddition to the high-resolution SWH, men wve direction, nd men wve period derived from the ERA-I glol renlysis, prmetric spectr in the shpe of JOSWAP spectrum (Hsselmnn et l., 97) were defined t ll ocen oundries. Therefore, under the model configurtion dopted, se surfce grvity wves in the TS were not only forced y the locl se surfce wind in the TS ut lso y the winds in the ECS, SCS, nd Pcific Ocen. The wve prmeters of interest were output every h on.. grid.. Oservtion Before conducting in-depth nlyses, it ws considered prudent to evlute the results derived from the wve model ginst oservtions. For tht purpose, we dopted wve height oservtions from oth uoys nd stellites. The red dots in Fig. show the loctions of the uoy sttions considered, nd detiled descriptions of the uoy oservtions re given in Tle. The uoy oservtions were provided y the Centrl Wether Bureu of Tiwn nd they cn e downloded vi Of the uoy sttions considered for verifiction, se surfce wind speed ws oserved t Jinmen, Mzu, Penghu, nd Prts. The uoy oservtions used here covered limited period from July to July with -h smpling intervl. Stellite oservtions were lso used. These included ner rel-time merged SWH (RT-SWH) nd delyed-time long trck SWH oserved y Topex/Poseidon, Json-, nd Json-. The RT- SWH dt were provided on glol.. grid with time intervl of one dy. The stellite missions used to prepre the RT-SWH included ERS- nd, Json-,, nd, Envist, Cryost, HY-, nd Srl to ensure t lest two missions were ville for the genertion of merged mp. Blended SWH oservtions were then cross-clirted using OSTM/ Json- s the reference mission. In the current study, the RT-SWH dt extended from Octoer 9 to July, while the long trck SWHs oserved y Topex/Poseidon, Json-, nd Json- extended from

4 o. OU et l.: Internnul wve climte vriility in TS Tle Comprison etween the simulted (SWA model) SWHs nd oserved (uoy) SWHs Men (m) Buoy nme R Bis (m) SI SWA Oservtion Dongjido Jinmen Mzu Penghu Prts All liner correltion coefficients presented re ove the 9% confidence level. Septemer 99 to Octoer, from Jnury to June, nd from June 8 to July, respectively. All stellite oservtions were provided y AVISO. To exmine the impct of the TC ctivities on the internnul wve climte vriility in the TS, the TC est-trck dtset ws used. This is prepred y the Regionl Specilized Meteorologicl Center of the Tokyo Typhoon Center nd it includes the -hourly positions (TC ltitude nd longitude), intensity grdes, nd centrl pressures of those TCs ppering in the western orth Pcific Ocen during Jnury 979 to July. To investigte the possile reltionship etween the wve climte vriility in the TS nd the ESO phenomenon, the se surfce temperture nomly verged over the iño-. region ws used s the ESO index. For the current study, the ESO index, downloded vi dt/cm/ersst/v/index ws clculted using the Extended Reconstructed Se Surfce Temperture dtset version (Hung et l., ).. Method It hs een proven tht the wve energy per unit surfce re ( E ; unit: J/m ) is proportionl to the squre of the comined SWH (Chen et l., ; Jing nd Chen, ): E = ρ g( H M /), where ρ, g, E, nd H M denote the reference se wter density, grvittionl ccelertion, wve energy, nd comined SWH, respectively. Here, ρ ws set to kg/m nd g ws set s 9.8 m/s. Thus, the wve energy in the TS during different periods of ech month could e estimted ccordingly. For exmple, in August 99, TCs influenced the TS (See Section.. for more detils) on out d. Therefore, the wve energy with TC influence during this month ws estimted s the sum of E during those d, while the wve energy without TC influence ws otined y summing the wve energy during the rest of the month. In the current study, the internnul nomlies of the vriles of interest were clculted s follows. For monthly vriles, monthly men nomlies were otined through sutrcting the monthly climtology from the originl monthly mens. Then, -month running men filter ws pplied to exclude sunnul signls. MODEL VALIDATIO. Comprison with uoy oservtions A comprison of the -hourly SWHs hindcsted y the high-resolution SWA model nd those oserved y uoys is shown in Fig.. Overll, the model hindcsted SWHs gree resonly well with the uoy oservtions in terms of oth mgnitude nd temporl phse. Their simultneous correltions re ll >.8 ove the 9% confidence level t the five uoy sttions. The men ises (Tle ), computed s the model results sutrcting the uoy oservtions, indicte tht the wve model slightly underestimtes SWH t most uoy sttions, especilly when the wves re lrge. At Penghu sttion, however, the wve model slightly overestimtes SWH during most of the oservtion period. onetheless, the ises re considerly low when compred with the men SWH. The rtios of the ises to the oserved SWHs re <% in their mgnitudes t most uoy sttions, nd the sctter indexes (SIs) re lso low, i.e., in the rnge..9. A comprison of the -hourly se surfce wind speeds derived from the ERA-I glol renlysis nd those oserved t four of the uoy sttions is presented in Fig.. Overll, these two dt sets of se surfce wind speed gree resonly well in terms of oth temporl phse nd mgnitude. The simultneous correltions etween them t the four uoy sttions rnge from.79 to.8 ove the 9% confidence level. Moreover, the men wind speeds from the ERA-I glol renlysis nd uoy oservtions re oth out.8.9 m/s (Tle ). However, we lso note tht the ERA-I glol renlysis slightly underestimtes the oserved se surfce wind speeds t the Jinmen nd Mzu uoy sttions with ises of out -.7 nd -. m/s, respectively. Conversely, the oservtions t the Penghu nd Prts uoy sttions re slightly overestimted with ises of up to. nd.7 m/s, respectively. However, the ises

5 J. OCEAOL. LIMOL., (), 8 Vol. Dongjido R=.8 SWA Osvtion Jinmen R=.87 SWH (m) 8 Mzu Penghu R=.88 R=.88 8 Prts R= Time Fig. Six-hourly SWH (unit: m) output y the wve model (red line) nd tht oserved y uoys (lck dshed line) t the Dongjido, Jinmen, Mzu, Penghu, nd Prts uoy sttions In ech pnel, the numer denotes the simultneous liner correltion etween the two time series. re rther low compred with the men vlues. The rtios of the ises to men vlues re.% 9.% in terms of mgnitude, nd the SIs t the four uoy sttions re lso generlly low, i.e., out Comprison with stellite oservtions A comprison of the model simultion nd stellite oservtions is presented in Fig., from which it cn e seen tht the wve model hindcst grees resonly well with the stellite oservtions. Their SIs re generlly low, rnging from. to.9; however, it should e noted tht the lest squres fitted slopes etween the model hindcst nd stellite oservtions re.8 for RT-SWH nd.77 for ll delyed-time SWHs. This mens the hindcsted SWHs re slight underestimtes in comprison with the stellite oservtions. The simultneous liner correltion coefficient etween the dily time series of the hindcst SWH Tle Sme s Tle ut for the wind speed t m ove the se surfce Men (m/s) Buoy mes CC Bis (m/s) SI ERA-I Os. Jinmen Mzu Penghu Prts nd RT-SWH is shown in Fig.e. In the fr western orth Pcific Ocen nd the djcent Chin ses, the correltions re much lrger thn.7 ove the 9% confidence level, indicting resonly good greement etween their temporl fluctutions. In the djcent Chin ses, the correltion is much lrger thn.8 in most res of the SCS, nd etween.7 nd.8 in most regions of the ECS nd the Yellow Se.

6 o. OU et l.: Internnul wve climte vriility in TS Jinmen R=.79 Wind Speed (m/s) Mzu R=.8 ERI Oservtion Penghu R=.87 Prts R= Time Fig. Sme s Fig. ut for the -hourly wind speed (unit: m/s) t m ove the se surfce Bsed on the ove nlyses, it ws concluded tht the SWA model ws cple of reproducing the SWH vritions in the regions of interest. However, it should e noted tht the wve model results generlly underestimte the oserved SWH. One possile reson is tht we dopted the defult prmeter vlues in the model, which might tend to produce SWHs smller thn the oservtions (Jing et l., ). RESULT. Sesonl vriility The climtologicl men SWH over the entire study period is shown in Fig.. It cn e seen tht SWH is lrgest in the western orth Pcific Ocen nd it then decreses towrd the djcent Chin ses. There re two tongues of high SWH: one extending northwrd into the ECS nd the other extending westwrd into the SCS. The SWH in the TS, however, is reltively smll. As shown in Fig., the lrgest SWH in the TS, which is out. m, occurs round the middle of the strit with SWHs then decresing shorewrd. The re-verged SWH in the TS is only out.9 m, much lower thn in the western orth Pcific Ocen t the sme ltitude. Across the northern nd southern oundries of the TS, there re two tongues of high SWH: one extending southwrd from the ECS nd the other extending northwrd from the SCS, respectively. This might imply tht the wve climte in the TS is possily influenced y tht in the ECS, SCS, nd even the western orth Pcific Ocen. The stndrd devition (SD) of the monthly SWH (Fig.c) shows rther different sptil distriution from tht of the climtologicl men SWH. In the western orth Pcific Ocen nd djcent Chin ses, the SD of the SWH hs two regions of high vlues well ove. m, which re locted est of Luzon nd long northest-southwest nd extending from the

7 J. OCEAOL. LIMOL., (), 8 7 SI=. = α=.77 SWH model (m) SI=. =79 α= Vol SWH T/P (m) 7 7 SI=.9 =89 α=.8 d SWH model (m) SWH Json (m) SI=. =7 α=.77 c 9 7 SWH Json (m) e SWH RT (m) E.7 Fig. Sctter digrms of the SWH (unit: m) hindcsted y the wve model nd those oserved y () TOPEX/Poseidon, () Json-, nd (c) Json-, respectively; sctter digrm of the wve model hindcsted SWH (unit: m) nd RT-SWH (unit: m) (d); simultneous correltion mp etween the dily time series of the model hindcsted SWH nd RT-SWH (e) In d, nd α denote the numer of selected grids nd the slope of the lest squres line, respectively. The color legend depicts the numer of dt within.. m grid ox during the period of interest. ote tht only correltions >.7 ove the 9% confidence level re presented in (e).. c E. d E. SWH (m) e Jn. Fe. Mr.. Apr.. My Jun. Jul. Aug. Sep. Oct. ov. Dec. Month E Fig. Climtologicl men SWH (unit: m) over the Chin ses nd djcent wters (), sme s Fig. ut over the TS (), SD (unit: m) of the monthly SWH (c), climtologicl monthly SWH (unit: m) verged over the entire TS (d), nd SD of the climtologicl monthly SWH over the computtion domin (e) In () the contour intervl is. m, wheres it is. m in (), (c), nd (e).

8 o. OU et l.: Internnul wve climte vriility in TS.... E E c E. d SWH Ano. (m) Yer Fig. The SD of the internnul SWHA (unit: m) (), sme s Fig. ut over the TS (), simultneous correltion coefficient etween the internnul SWHA t ech grid point nd tht verged over the entire TS (only correltion coefficients ove the 9% confidence level re presented) (c), nd time series of the internnul SWHA (unit: m) verged over the entire TS (d) Contour intervls in (), (), nd (c) re. m,. m, nd., respectively. Luzon Strit to est of the Vietnm cost in the SCS. The re-verge SD of the SWH in the TS is out. m, while the mximum vlue, which occurs in the middle of the strit, is out. m. The climtologicl monthly SWH verged over the entire TS region is shown in Fig.d. It cn e seen tht SWH in the TS hs considerle sesonl vrition, reching mximum of.8 m in ovemer nd minimum of.8 m in My. This is consistent with historicl oservtions (Guo et l., ). The SD of the climtologicl monthly SWH (Fig.e) in the western orth Pcific Ocen shows similr sptil distriution to tht of the monthly SWH (Fig.c). In the TS, the SD of the climtologicl monthly SWH is lso similr to tht of the monthly SWH (Fig.c). The re-verged SD of the climtologicl monthly SWH over the entire TS is out.7 m, i.e., nerly equl to tht of the monthly SWH. Therefore, the wve climte in the TS is dominted y the sesonl vrition.. Internnul vriility The SD of the internnul SWH nomly (SWHA) over the entire computtion domin is shown in Fig.. Overll, it is much smller thn tht of the nnul cycle (Fig.e) nd it hs different sptil distriution. There re two regions with high SD vlues of the internnul SWHA, which re locted in the western orth Pcific Ocen nd long northest-southwest nd in the middle of the SCS (Fig.). The SD of the internnul SWHA in the TS is reltively smll nd it is not sptilly uniform (Fig.). It shows regionl mximum t round., 9. E, which is out. m smller thn in oth the western orth Pcific Ocen nd the SCS. However, it is generlly smller thn tht of the nnul cycle (Fig.e). The reverged SD in the TS is only out.7 m, i.e., much smller thn tht of the climtologicl monthly SWH. The time series of the internnul SWHA verged in the TS is presented in Fig.d. It is considerly

9 8 J. OCEAOL. LIMOL., (), 8 c Vol. E e E f E g E E E d E h E Fig.7 Mps of the SD of the sesonl men SWHA (unit: m) in () spring, () summer, (c) utumn, nd (d) winter in the western orth Pcific Ocen nd the djcent Chin ses (e) (h) sme s () (d), respectively, ut over the TS. ote, contour intervls in () (d) nd (e) (h) re. m nd. m, respectively. negtive during the yers round 98, 98, 99, 997, 9, nd ut positive during the yers round 98, 988, 998, 7, nd. Given tht El iño or L iñ events occurred in these yers, it could e expected tht the internnul vriility of SWH in the TS would e relted strongly with ESO events (s discussed in Section.). The simultneous liner correltion coefficients etween the internnul SWHAs t ll grid points round the TS nd tht verged over the entire TS re shown in Fig.c. Overll, the correltion coefficient is generlly >.9 in the TS nd it then decreses wy from the strit. The high correltion in the TS indictes tht the entire TS shres nerly the sme temporl vritions in SWH on the internnul time scle. Therefore, the internnul SWHA verged in the TS could e used to represent the internnul wve climte vriility in the TS. Mps of the SD of the sesonl men SWHA in the four sesons re presented in Fig.7. In the current study, the sesons refer to those of the orthern Hemisphere, i.e., summer refers to June August nd winter refers to Decemer Ferury. It cn e seen from Fig.7 tht the SDs of the sesonl men SWHA in the TS re lrger in utumn nd winter thn in the other two sesons. The re-verged SDs of the sesonl men SWHA in the TS in utumn nd winter re. nd. m, respectively, while those in summer nd spring re.8 nd.7 m, respectively. It mens tht the internnul SWH vriility in the TS is much stronger in utumn nd winter thn in summer nd spring. In spring, utumn, nd winter, the sptil distriutions of the SDs of the sesonl men SWHA in the TS re similr to ech other, with the highest vlues ppering in the middle of the strit. Outside the strit, the SD of the sesonl men SWHA is generlly high in the western orth Pcific Ocen nd the SCS. The SD mximum in the SCS lwys occurs round the Luzon Strit in ll three sesons. However, in summer, the SD in the TS shows no regionl mximum in the middle re. The SD mximum in the SCS occurs in the southern prt, which is lso mrkedly different from the other sesons. Therefore, the internnul SWH vriility in summer might e mrkedly different from the other three sesons from the perspective of dynmics.. Dynmics The temporl vrition nd sptil distriution of surfce grvity wves re relted closely to those of se surfce wind forcing (Xu et l., 7). Hence, it is importnt to exmine the reltionship of the

10 o. OU et l.: Internnul wve climte vriility in TS 9 SWH no. (m) SWH no. (m) SWH no. (m) SWH no. (m) SWH no. (m).. -. R=.7 SWH no. Wind speed no Spring R= Yer c Summer R= Yer d Autumn R= Yer e Winter R= Yer Fig.8 Internnul nomlies of SWH (unit: m; lck solid line) nd se surfce wind speed (unit: m/s; lck dshed line) verged over the entire TS () () (e) sme s () ut for sesonl men nomlies in spring, summer, utumn, nd winter, respectively Wind speed no. (m/s) Wind speed no. (m/s) Wind speed no. (m/s) Wind speed no. (m/s) Wind speed no. (m/s) internnul SWH vriility in the TS to se surfce wind forcing oth inside nd outside the TS. The internnul nomlies of SWH nd se surfce wind speed (WS) verged over the entire TS re compred in Fig.8. Overll, they gree resonly well, with the simultneous liner correltion coefficient eing out.7 ove the 9% confidence level. However, it should e noted tht they exhiit very different temporl phses during some periods, e.g., August Septemer 99, July August 99, July Septemer 998, nd August. The sesonl men nomlies of SWH nd se surfce WS verged over the TS in the four sesons re shown in Fig.8 e. Interestingly, the correltion etween SWH nd se surfce WS in summer is mrkedly different from the other three sesons. In summer, the liner correltion coefficient is only out -.7, implying no significnt liner correltion etween them. In the other three sesons, however, the liner correltion coefficients re ll >.7 ove the 9% confidence level. The highest correltion occurs in winter ( R =.9). The different correltions suggest strongly tht the dynmics responsile for the internnul SWH vriility in summer should e mrkedly different from those in the other three sesons. Previous studies hve indicted tht the TS is dominted y strong northesterly monsoon winds from Octoer to Mrch in the following yer, wheres the region is ffected y wek southwesterly monsoon winds during the rest of the yer (Chen et l., ; Guo et l., ). The ove correltion nlyses indicte tht the internnul SWH vriility in utumn, winter, nd spring is minly forced y the

11 J. OCEAOL. LIMOL., (), 8 Vol. TC durtion TC count TC durtion (dy) or count no. (numer/month) Jn. Fe. Mr. Apr. My Jun. Jul. Aug. Sep. Oct. ov. Dec. Month TC durtion no. TC count no. SWH no Yer Fig.9 Climtologicl monthly frequency (unit: numer in one month) nd durtion (unit: d) of TCs within the ffected region (), nd summer men nomlies of the frequency (unit: numer in one month) nd durtion (unit: d) of TCs within the ffected region nd the SWH verged in the TS (unit: m) () SWH no. (m) northesterly monsoon winds, while tht in summer hs no significnt correltion with the southwesterly monsoon winds. The exct dynmics re discussed in the following... Summer In previous studies, mny reserchers hve climed tht the TS nd its djcent res re ffected considerly y strong TC ctivities during summer, in ddition to southwesterly monsoon winds (Ji et l., ). Given the poor correltion etween the internnul SWH vriility in the TS nd the southwesterly monsoon winds, it is useful to exmine whether TC ctivities mke significnt contriution. For this nlysis, we dopted the TC est-trck dtset derived from the Regionl Specilized Meteorologicl Center of the Jpn Meteorologicl Agency (eedhm et l., ). Sttisticlly, the mximum rdii of regions with wind speeds of kt (~ m/s) when TCs pss re pproximtely km (Fng et l., 987; Hu et l., ), which is equivlent to in ltitude or longitude. Therefore, we defined n ffected region (9, E) round the TS center of., 9. E. Thus, when TC center ws locted within the ffected region, the TC ws considered to ffect the wve field in the TS sustntilly. The climtologicl monthly frequency nd durtion (in dys) of TCs tht influence the TS re shown in Fig.9 (Sski et l., ; Bromirski et l., ). Here, the frequency ws defined s the numer of TCs in one month within the ffected region. The durtion ws clculted s the numer of dys within one month when the TS ws influenced y TCs. It cn e seen tht TCs occur mostly during June Septemer, nd tht the mxim of frequency nd durtion oth occur in August. These findings re consistent with previous studies (Chn, ). Thus, in the following, summer refers to the months of June Septemer. The time series of the summer men nomlies of the frequency nd durtion of TCs influencing the TS re presented in Fig.9, together with the SWHA

12 o. OU et l.: Internnul wve climte vriility in TS PSD (m /yer)..... PSD (dy /yer) c PSD (/yer) Period (yer) Fig. Power spectr of the summer men nomlies of the SWH verged in the TS (unit: m /yer) (), the durtion (unit: d /yer) (), nd frequency of the TCs (unit: /yer) influencing the TS (c) In ech pnel, the solid line denotes the power spectrl density, while the dshed line represents the 9% confidence level for red noise. verged over the TS. It is interesting tht the summer men nomlies of oth the frequency nd durtion of TCs show significnt correltions with tht of the SWH in the TS. Their simultneous liner correltions re. nd., respectively, oth ove the 9% confidence level. We lso clculted the power spectr of the three vriles (Bin, 97) to explore their dominnt vrying periods (Fig.). Interestingly, ll three vriles shre dominnt vrying period of out.8 yers, which is significnt t the 9% confidence level. This further suggests tht the internnul SWH vriility in summer in the TS is ffected strongly y TC ctivities. It should e noted tht TCs re synoptic nd tht they hve short durtions within the ffected region round the TS. This prompts the question of why the summer men nomly of SWH is correlted more significntly with TC ctivities thn with the southwesterly monsoon wind. To investigte this, we clculted the men wve energy in the TS in summer during dys with nd without TCs locted in the ffected region. We should note tht the totl wve energy in the summer seson is proportionl to the squre of the summer men SWH. The time series of the summer men wve energy ( E ) is plotted ginst tht with TCs ( E T ) nd without TCs ( E M ) in Fig.. These series were clculted s follows. The totl wve energy, wve energy with TCs, nd tht without TCs in summer were first clculted sed on the -hourly outputs (s descried in Section.). Then, the results were divided y the totl numer of time points in this seson. As cn e seen from the figure, E T is much lower thn E M throughout the yers of interest. However, the fluctution of the former is much stronger thn the ltter. The SD of E T is out 8.9 J/m, i.e., 9.% higher thn tht of E M, which is out. J/m. Menwhile, E T shows greter correltion with E ( R =.8) thn does E M ( R =.). This implies strongly tht E T domintes the internnul vriility of E in summer nd hence, the internnul vriility of the summer men SWH. Figure further compres the

13 J. OCEAOL. LIMOL., (), 8 Vol. Summer men wve energy Summer men wve energy with TCs Summer men wve energy without TCs Wve energy (J/m ) TC durtion (dy) or count no. (numer/month) TC durtion no. TC count no. Summer men wve energy no. Summer men wve energy no. with TCs Summer men wve energy no. without TCs Yer Fig. Time series of E (unit: J/m ), E T (unit: J/m ), nd E M (unit: J/m ) (), nd nomlies of E (unit: J/m ), E T (unit: J/m ), E M (unit: J/m ) (), nd the frequency (unit: numer in one month) nd durtion (unit: d) of TCs influencing the TS in the summer seson Wve energy no. (J/m ) nomlies of the summer men wve energy nd those of TC properties. The dominnce of E T in the vritions of E cn e clerly seen. Their nomlies show resonle greement with ech other in terms of oth temporl phse nd mgnitude. Furthermore, nomlies of oth the frequency nd the durtion of the TCs tht influence the TS show significnt correltions with the nomly of E ( R =. nd R =., respectively). Therefore, we cn conclude tht TC ctivities dominte the internnul vriility of SWH in the TS in summer, while the southwesterly monsoon winds mke secondry contriution... Winter In winter, the TS is dominted y northesterly surfce grvity wves under the forcing of northesterly monsoon winds (figure not shown). In the following, given the months of the previling northesterly monsoon winds, winter denotes the months of Octoer Mrch. As shown in Fig.8, in the TS, the SWHAs re correlted significntly with the locl se surfce WS nomlies in utumn, winter, nd spring when the northesterly monsoon winds previl. Menwhile, Fig.7 shows tht the SD mxim of the sesonl men SWHA occur in the middle re of the TS during these sesons. Therefore, it would pper tht the internnul SWH vriilities in these sesons re controlled minly y locl se surfce wind forcing in the TS. To investigte this point, we conducted nother model simultion with smller computtion domin. In the following discussion, the model simultion using the lrge computtion domin, s shown in Fig., is denoted CTR, while tht using the smll computtion domin is denoted EXR. The model configurtions of EXR were mostly the sme s CTR, except with regrd to the computtionl domin nd the oundry conditions. As shown in Fig., the computtionl domin of EXR covers the region, 7 E. Free oundry conditions were pplied to ll ocen oundries of the EXR domin. The climtologicl men SWH ( H EXR ) output y EXR is presented in Fig.. It cn e seen tht the sptil distriution of H EXR outside the TS is notly

14 o. OU et l.: Internnul wve climte vriility in TS E. c. H CTR no. H EXR no. SWH no. (m) (H CTR H EXR ) no E Yer Fig. Climtologicl men SWH output y EXR ( H EXR ; unit: m) (). The contour intervl is. m. SD of the men nomlies of H EXR (unit: m) in the northesterly monsoon sesons (). The contour intervl is. m. Time series of the men nomlies of the re-verged H CTR (unit: m; lck solid line), H EXR (unit: m; lck dshed line), nd ( H CTR H EXR ) (unit: m; red dshed line) in the TS in the northesterly monsoon sesons (c) different from tht of the climtologicl men SWH ( E CTR ) output y CTR (Fig.) ecuse of the smll computtion domin nd free oundry conditions of EXR. However, the sptil distriutions of the climtologicl mens H EXR nd H CTR inside the TS re similr, i.e., H EXR in the TS is lso lrgest in the middle re nd it then decreses shorewrd. Overll, H EXR is slightly smller thn H CTR. The lrgest vlue of H EXR in the TS is.8 m, which is.7% lower thn the lrgest vlue of H CTR (. m). Moreover, the reverged H EXR over the TS is out.9 m, which is.% lower thn the re-verged H CTR (.9 m). Furthermore, during the northesterly monsoon sesons, the SD of the men nomlies of H EXR (Fig.) is lso similr to tht derived from the CTR simultion (Fig.7e, g, nd h) in terms of oth sptil distriution nd mgnitude, i.e., it shows high vlues in the middle re of the strit. The re-verged SD of H EXR over the TS is out. m, resonly similr to tht of H CTR. Figure c further compres the time series of the men nomlies of the re-verged H CTR nd H EXR in the TS during the northesterly monsoon sesons. As expected, they gree resonly well with ech other in terms of oth temporl vrition nd mgnitude. Their simultneous liner correltion is out.99 ove the 99% confidence level, nd their SDs re. nd. m, respectively. Their difference is shown s the red dshed line, which hs n pproximtely zero verge with the SD eing. m. Therefore, it is suggested strongly tht the wve climte in the TS during the northesterly monsoon sesons is controlled y locl se surfce wind forcing.

15 J. OCEAOL. LIMOL., (), 8 Vol. SWH no. (m) SWH no. ESO index Yer ESO index ( C) ESO index led ESO index lg CC Fig. Time series of the internnul SWHA verged over the TS (unit: m; solid line) nd the ESO index (unit: C, dshed line) (); lgged correltions etween the two time series () All correltion coefficients re ove the 9% confidence level. -.7 Led/lg months. Reltionship to ESO Previous studies hve shown tht the internnul vriility of the SWH round the Tiwn Islnd is modulted y the ESO cycle (Chien et l., ). Therefore, it is meningful to exmine further the potentil reltionship etween internnul wve climte vriility in the TS nd the ESO phenomenon. The time series of the ESO index nd the internnul SWHA verged over the TS, compred in Fig., generlly show vritions with opposite phses. During strong El iño yers (e.g., 98/98, 99/99, nd 997/998), SWH in the TS shows significntly negtive nomlies, while during L iñ yers (e.g., 98/98, 988/989 nd 998/999), positive nomlies of SWH re evident. We clculted the lgged correltions etween the two time series. As shown in Fig., the monthly SWH nomly is correlted highly negtively with the ESO index ( R =-.) ove the 9% confidence level when the ltter leds the former y out two months. Menwhile, their simultneous correltion is out -.8 ove the 9% confidence level. This is similr to the sitution t the Longdong uoy sttion, which is locted to the northest of Tiwn Islnd. Bsed on uoy oservtions, Chien et l. () indicted tht the nnul men of the nomlies of SWH t the Longdong sttion is correlted highly positively ( R =.8) ove the 9% confidence level with the nnul men Southern Oscilltion index. As discussed in Section., the dynmics responsile for the internnul wve climte vriility in the TS in summer re mrkedly different from winter. Therefore, it is helpful to exmine the reltionships in these two sesons... Summer The lgged correltion etween the summer men SWHA nd the ESO index is shown in Fig.. It cn e seen tht the summer men SWHA is correlted modertely positively with the ESO index ( R =.) ove the 9% confidence level with no significnt time lgs. This is notly different from tht etween the internnul SWHA nd the ESO index shown in Fig.. As discussed in Section.., the internnul wve climte vriility in the TS during summer is controlled predominntly y TC ctivities. Therefore, the significntly positive correltion etween the summer men SWHA nd the ESO index implies

16 o. OU et l.: Internnul wve climte vriility in TS CC Led/lg months tht TC ctivity in the western orth Pcific Ocen nd the djcent ses is correlted highly positively with the ESO index. Indeed, previous studies hve reveled pronounced reltionship etween ESO events nd TC ctivities in the western orth Pcific Ocen nd the djcent ses (Chn, 98, ; Dong, 988; Lnder, 99; Chen et l., 998). During El iño summers, more TCs with longer life spns tend to form in the estern prt of the northwestern Pcific Ocen efore following curving pth towrd the ECS nd Jpn (Chn, 98, ; Dong, 988; Lnder, 99; Elsner nd Liu, ; Chu, ), resulting in significntly intensified TC ctivities over the TS. During L iñ summers, however, TCs tend to form in res further west efore trcking westwrd or west-northwestwrd cross the Philippines nd the SCS (Elsner nd Liu, ), resulting in wekened TC ctivities over the TS... Winter ESO index led ESO index lg Fig. Lgged correltion (solid line) etween the ESO index nd the summer men SWH nomly verged over the TS Dshed lines indicte correltion coefficients t the 9% confidence level. The lgged correltion etween the winter men SWHA nd the ESO index is shown in Fig.. Different from the sitution in summer, the winter men SWHA shows significntly negtive correltion with the ESO index ( R =-.9) ove the 9% confidence level when the ltter leds the former y out one month. This is similr to tht etween the totl time series of the internnul SWHA nd the ESO index shown in Fig.. As discussed in Section.., the internnul wve climte vriility in the TS in winter is controlled predominntly y the northesterly monsoon winds. Therefore, the ove negtive correltion suggests strongly tht internnul monsoon wind vriility over the TS should e correlted negtively with the ESO index. Simultneous regression mps of the winter men nomlies of se surfce wind vectors nd wind speeds ginst the normlized winter men ESO index re displyed in Fig.. The most prominent feture in the regression mp is the existence of significnt nticyclonic wind nomlies over the fr western Pcific Ocen nd the SCS. The southwesterly wind nomlies over the TS reduce the northesterly winter monsoon there, inducing negtive se surfce wind speed nomlies. To elucidte this, we clculted the composite winter men nomlies of se surfce wind vectors nd surfce wind speeds during oth El iño yers (Fig.c) nd L iñ yers (Fig.d). The results gree resonly well with the ove regression mps (Fig.). During El iño winters, there re significnt nticyclonic wind nomlies over the western Pcific Ocen nd the SCS. Over the TS, the southwesterly wind nomlies led to significntly negtive nomlies in se surfce wind speed; however, during L iñ yers, the sitution is reversed. The weker (stronger) thn norml winter monsoon long the Est Asin cost during El iño (L iñ) yers hs lredy een noted in previous studies (Tomit nd Ysunri, 99; Zhng et l., 99; Ji et l., 997). From the perspective of dynmics, it is forced y the lower-tropospheric nomlous nticyclone (cyclone) tht is present over the western Pcific Ocen nd the SCS during El iño (L iñ) yers (Wng et l., ; Wng nd Zhng, ; He nd Wng, ). COCLUSIO Bsed on the output of high-resolution numericl wve model, this study investigted the chrcteristics nd underlying dynmics of the internnul wve climte vriility in the TS. The results demonstrted tht the internnul vriility of SWH in the TS is weker thn the sesonl vriility. Generlly, the SD of the internnul SWHA is lrgest in the middle of the strit nd it then decreses shorewrd. It shows similr sptil distriutions throughout the yer, except in summer, when there is no regionl mximum in the middle of the strit. Such results might imply tht the internnul SWH vriility in summer is mrkedly different from tht in the other sesons from the perspective of dynmics.

17 J. OCEAOL. LIMOL., (), 8.. ESO index led Vol.. ESO index lg. m/s S 8 Led/lg months 8-9. c m/s. E -.. d m/s S - 9 E -. S E Fig. Sme s Fig. ut etween the ESO index nd winter men SWHA verged over the TS (). Simultneous regression mps of the winter men nomlies of se surfce wind vectors (gry rrow; unit: m/s) nd wind speeds (color; unit: m/s) over the western Pcific Ocen nd the djcent ses ginst the normlized winter men ino. index (). Composite winter men nomlies of se surfce wind vectors (gry rrow; unit: m/s) nd wind speeds (color; unit: m/s) during El iño yers (c). Sme s (c) ut during L iñ yers (d) In () (d), the contour intervl is. m/s nd the lck dots denote the results ove the 9% confidence level sed on two-sided Student s t-test. As se surfce grvity wves re ll generted y se surfce wind forcing, the reltionship etween the internnul vritions of the monthly men SWH nd se surfce wind speed over the TS ws exmined. Unexpectedly, the internnul SWH nomly showed very low correltion with tht of the monthly men se surfce wind speed in summer when southwesterly monsoon winds previl. During the northesterly monsoon sesons, however, the correltions were very significnt. This further suggests tht the underlying dynmics responsile for the internnul wve climte vriility in the TS re different during the southwesterly monsoon seson in comprison with the northesterly monsoon sesons. Indeed, further nlysis indicted tht the internnul wve climte vriility in the TS in summer is controlled predominntly y TC ctivities, while tht in winter is forced y northesterly monsoon winds. We lso explored the reltionship of the internnul wve climte vriility in the TS with the ESO phenomenon, which is the most ctive lrge-scle climtic vriility in the tropicl Pcific Ocen. Overll, the internnul SWHA in the TS showed significnt correltion with the ESO index (R= -.) ove the 9% confidence level when the former lgged the ltter y out two months. This reltionship is derived minly from tht during the northesterly monsoon sesons. During the northesterly monsoon sesons in El iño (L iñ) yers, there is lower-tropospheric nomlous nticyclone (cyclone) over the western Pcific Ocen nd the SCS (e.g., Wng et l., ; Wng nd Zhng, ). This nomlous nticyclone (cyclone) lrgely wekens (strengthens) the northesterly monsoon winds in the TS, resulting in negtive (positive) SWHA there. During the summer seson in

18 o. OU et l.: Internnul wve climte vriility in TS 7 El iño yers, however, more TCs with longer life spns tend to form in estern prts of the northwestern Pcific Ocen efore following curving pth towrd the ECS nd Jpn (Chn, 98, ; Dong, 988; Lnder, 99; Elsner nd Liu, ; Chu, ). Intensified TC ctivities over the TS induce significnt positive SWHA. During L iñ summers, however, TCs tend to form in res further west efore following westwrd or west-northwestwrd trcks cross the Philippines nd the SCS (Elsner nd Liu, ), resulting in wekened TC ctivities over the TS. DATA AVAILABILITY STATEMET The detils of the dt tht support the findings of this study re descried in Section, including the providers nd wesites from which the dt cn e downloded freely. 7 ACKOWLEDGEMET The uthors would like to thnk Dr. LIU Cong of the Ocen University of Chin for providing helpful dvice during this work, from guidnce on its structure to editing of the pper. References Bin W C. 97. The power spectrum of tempertures in centrl Englnd. Qurterly Journl of the Royl Meteorologicl Society, (): -. Bttjes J A, Jnssen J P F M Energy loss nd set-up due to reking of rndom wves. In : Proceedings of the th Interntionl Conference on Costl Engineering Conference. Americn Society of Civil Engineers, Hmurg, Germny. p Booij, Ris R C, Holthuijsen L A third-genertion wve model for costl regions:. Model description nd vlidtion. Journl of Geophysicl Reserch : Ocens, (C): Bromirski P D, Cyn D R, Helly J, Wittmnn P.. Wve power vriility nd trends cross the orth Pcific. Journl of Geophysicl Reserch : Ocens, 8 (): 9-8. Chn J C L. 98. Tropicl cyclone ctivity in the northwest Pcific in reltion to the El iño/southern Oscilltion phenomenon. Monthly Wether Review, (): 99-. Chn J C L.. Tropicl cyclone ctivity over the western orth Pcific ssocited with El iño nd L iñ events. Journl of Climte, (): Chn J C L.. Internnul nd interdecdl vritions of tropicl cyclone ctivity over the western orth Pcific. Meteorology nd Atmospheric Physics, 89 (-): -. Chng C K, Chien C C.. The studies of the typhoon wve chrcteristic t the estern cost of Tiwn. In : Asin nd Pcific Costl Engineering. Dlin University of Technology Press, Dlin, Chin. p Chen G, Chpron B, Ezrty R, Vndemrk D.. A glol view of swell nd wind se climte in the ocen y stellite ltimeter nd sctterometer. Journl of Atmospheric nd Ocenic Technology, 9 (): Chen H X, Hu F, Yun Y L.. Sesonl chrcteristics nd temporl vritions of ocen wve in the Chinese offshore wters nd djcent se res. Advnces in Mrine Science, (): 7-. (in Chinese with English strct) Chen T C, Weng S P, Ymzki, Kiehne S Internnul vrition in the tropicl cyclone formtion over the western orth Pcific. Monthly Wether Review, (): 8-9. Chen X, Sh W Y, Min J Z.. The simultion of typhoon wves round Tiwn Islnd. Mrine Forecsts, 9 (): -. (in Chinese with English strct) Chien H, Cheng H Y, Chiou M D.. Wve climte vriility of Tiwn wters. Journl of Ocenogrphy, 7 (): -. Chu P S.. ESO nd tropicl cyclone ctivity. Accessed on --. Dee D P, Uppl S M, Simmons A J, Berrisford P, Poli P, Koyshi S, Andre U, Blmsed M A, Blsmo G, Buer P, Bechtold P, Beljrs A C M, vn de Berg L, Bidlot J, Bormnn, Delsol C, Drgni R, Fuentes M, Geer A J, Himerger L, Hely S B, Hersch H, Hólm E V, Isksen L, Kållerg P, Köhler M, Mtricrdi M, Mclly A P, Monge-Snz B M, Morcrette J J, Prk B K, Peuey C, de Rosny P, Tvolto C, Théput J, Vitrt F.. The ERA-interim renlysis: configurtion nd performnce of the dt ssimiltion system. Qurterly Journl of the Royl Meteorologicl Society, 7 (): -97. Dong K El iño nd tropicl cyclone frequency in the Austrlin region nd the northwest Pcific. Austrlin Meteorologicl Mgzine, : 9-. Eldeerky Y. 99. onliner Trnsformtion of Wve Spectr in the ershore Zone. Delft University of Technology, Delft, The etherlnds. p. Elsner J B, Liu K B.. Exmining the ESO-typhoon hypothesis. Climte Reserch, (): -. Fng W L, Xu Q M, Zhng J L, Tn C B Distriution of the wind speed in typhoons over the Est Chin Se. Mrine Forecsts, (): -. (in Chinese with English strct) Feng S Z, Li F Q, Li S J.. An Introduction to Mrine Science. Higher Eduction Press, Beijing, Chin. p.- 7. (in Chinese) Guo T T, Go W Y, Go Y, Gong F.. An nlysis of the climte chrcteristics for Tiwn Strit. Mrine Forecsts, 7 (): -8. (in Chinese with English strct) Hsselmnn K, Brnett T P, Bouws E, Crlson H, Crtwright D E, Enke K, Ewing J A, Gienpp H, Hsselmnn D E,

19 8 J. OCEAOL. LIMOL., (), 8 Vol. Krusemn P, Meerurg A, Müller P, Olers D J, Richter K, Sell W, Wlden H. 97. Mesurements of wind-wve growth nd swell decy during the Joint orth Se Wve Project (JOSWAP). Deutches Hydrogrphisches Institut, Hmurg, Germny. p.-9. Hsselmnn S, Hsselmnn K, Allender J H, Brnett T P. 98. Computtions nd prmeteriztions of the nonliner energy trnsfer in grvity-wve specturm. Prt II: prmeteriztions of the nonliner energy trnsfer for ppliction in wve models. Journl of Physicl Ocenogrphy, (): He S P, Wng H J.. Oscillting reltionship etween the Est Asin winter monsoon nd ESO. Journl of Climte, (): Hu B H, Yng X Q, Tn Y K, Wng Y Q, Fn Y.. A new method for clculting the wind speed distriution of moving tropicl cyclone. Advnces in Atmospheric Sciences, 7 (): Hung B Y, Bnzon V F, Freemn E, Lwrimore J, Liu W, Peterson T C, Smith T M, Thorne P W, Woodruff S D, Zhng H M.. Extended reconstructed se surfce temperture version (ERSST.v): Prt I: upgrdes nd intercomprisons. Journl of Climte, 8 (): 9-9. Hwng C H, Yo C C, Lee W C.. Evlution of wve energy chnges in Tiwn. In : Proceedings of the Interntionl Conference on Energy nd Sustinle Development: Issues nd Strtegies. IEEE, Ching Mi, Thilnd. p.-. Jn S, Tseng Y H, Dietrich D E.. Sources of wter in the Tiwn Strit. Journl of Ocenogrphy, (): -. Jn S, Wng J, Chern C S, Cho S Y.. Sesonl vrition of the circultion in the Tiwn Strit. Journl of Mrine Systems, (-): 9-8. Ji H D, Pn W R, Zhng G R.. umericl simultion of tyhpoon wves in Tiwn Strit nd Ximen By. Mrine Forecsts, 7 (): -8. (in Chinese with English strct) Ji L R, Sun S Q, Arpe K, Bengtsson L Model study on the internnul vriility of Asin winter monsoon nd its influence. Advnces in Atmospheric Sciences, (): -. Jing H Y, Chen G.. A glol view on the swell nd wind se climte y the Json - mission: revisit. Journl of Atmospheric nd Ocenic Technology, (8): 8-8. Jing T S, Ren J L, Shen C Q.. Simultion of significnt wve height in the shllow shelf re y SWA model nd its improvement. Mrine Forecsts, (): 9-7. (in Chinese with English strct) Komen G J, Hsselmnn S, Hsselmnn K. 98. On the existence of fully developed wind-se spectrum. Journl of Physicl Ocenogrphy, (8): 7-8. Lnder M A. 99. An explortory nlysis of the reltionship etween tropicl storm formtion in the western orth Pcific nd ESO. Monthly Wether Review, (): -. Lin Y H, Fng M C.. The ssessment of ocen wve energy long the costs of Tiwn. Chin Ocen Engineering, (): -. eedhm H F, Keim B D, Sthirj D.. A review of tropicl cyclone-generted storm surges: glol dt sources, oservtions, nd impcts. Reviews of Geophysics, (): -9. Sski W, Iwski S I, Mtsuur T, Lizuk S.. Recent increse in summertime extreme wve heights in the western orth Pcific. Geophysicl Reserch Letters, (): L7. Tomit T, Ysunri T. 99. Role of the northest winter monsoon on the iennil oscilltion of the ESO/ monsoon system. Journl of the Meteorologicl Society of Jpn, 7 (): 99-. Wng B, Wu R G, Fu X H.. Pcific-Est Asin teleconnection: how does ESO ffect Est Asin climte? Journl of Climte, (9): 7-. Wng B, Zhng Q.. Pcific-Est Asin teleconnection. Prt II: how the Philippine se nomlous nticyclone is estlished during El iño development. Journl of Climte, (): -. Wng C Z, Deser C, Yu J Y, Diezio P, Clement A.. El iño nd southern oscilltion (ESO): review. In : Glynn P W, Mnzello D P, Enochs I C eds. Corl Reefs of the Estern Tropicl Pcific. Springer, Dordrecht, The etherlnds. p.8-. Xu Y, Bi F, Song J B, He H L. 7. The temporl nd sptil vritions in the Pcific wind nd wve fields for the period -. Act Ocenologic Sinic, (): -. Ymguchi M, Htd Y, Ohfuku M, Li M J, onk H.. -yer wve hindcst nd nlysis of wve height climte trend on the northwestern Pcific Ocen. Journl of Jpn Society for turl Disster Science, (): - 8. Zhng G Y, Zhng X D, Yu M G.. Chrcteristics nd distriution pttern of wind nd wve in se re of Tiwn. Mrine Science Bulletin, (): -. (in Chinese with English strct) Zhng R H, Sumi A, Kimoto M. 99. Impct of El iño on the Est Asin monsoon: dignostic study of the 8/87 nd 9/9 events. Journl of the Meteorologicl Society of Jpn, 7 (): 9-. Zheng C W, Chen X, Li C Y.. Oservtion of wve climte in surrounding wters of Tiwn Islnd. Journl of PLA University of Science nd Technology : turl Science Edition, 7 (): (in Chinese with English strct) Zheng C W, Pn J, Tn Y K, Go Z S, Rui Z F, Chen C H.. The sesonl vritions in the significnt wve height nd se surfce wind speed of the Chin s ses. Act Ocenologic Sinic, (9): 8-. Zhou H, Rorty H, Wen B Y.. Wve height mesurement in the Tiwn Strit with portle high frequency surfce wve rdr. Act Ocenologic Sinic, (): 7-78.