Dissolved organic carbon (DOC) is one of the largest pools of carbon in the ocean, and is of the same size as the carbon dioxide in the atmosphere. Estuaries connecting the land and the ocean are one of the most important DOC sources to the ocean, and play an important role in the global carbon cycle. Because of their complex chemical, physical, geological and biological properties, estuaries have become rich ecological environment. In this study, we investigated the seasonal distributions of DOC in the Taiwan Strait (TS) and Taiwanese rivers, aiming to understand the distributions and variations of DOC in different seasons. The results show that DOC concentrations are generally the highest in the upper estuary, and then decrease downstream due to mixing with the low DOC seawater. The process of river flow constantly accumulates terrestrial material, and the DOC shows positive correlations with Chl. a, CH4 and BOD (Biochemical Oxygen Demand), suggesting that biological activities and pollutions could be sources of DOC in the estuary. The DOC concentrations (salinity<1) varied in dry (Nov.-Apr.) and wet (May-Oct.) seasons with ranges of 42-1185 £gM (mean=245¡Ó254£gM; n=32) and 18-565 £gM (mean=183¡Ó151£gM; n=24), respectively. The total DOC flux of 25 rivers is 87.8 Gg C/yr, which can be translated to the fluxes of all rivers in Taiwan to be 101.9 Gg C/yr. The amount of DOC flux in Taiwan is only about 0.07% of the tropical area, but the per unit area flux (3.92 gC /m2 /yr) is almost twice those of the tropical rivers (2.13 gC /m2 /yr). In Taiwan, the population density and land use are higher than the world average. Consequently, the impacts of the environment by human activities reveal the utmost export of DOC, and need further investigation. Next, in the TS, the DOC shows significant negative correlations with Sigma-T, and the distributions of DOC are mainly controlled by physical mixing in both winter and summer. In the western TS, DOC concentration is relatively high, compared to the eastern part, and is because of low temperature and salinity, but high DOC coastal China current flowing from north to south. DOC concentration decreases with increasing depth owing to the intrusion at depth by the Kuroshio, which contains relatively low DOC. In winter, the import of coastal China current brings more nutrients from north to south, and supports the growth of bacteria which depletes the DOC and oxygen. As the result, DOC decomposition rate is higher in winter than in summer. The TS¡¦s DOC fluxes in summer (northern TS: 3.85¡Ñ1012mol C/yr¡Fsouthern TS: 3.75¡Ñ1012mol C/yr) are higher than in winter (northern TS: 3.69¡Ñ1012mol C/yr¡Fsouthern TS: 2.84¡Ñ1012mol C/yr). Main differences are due to the prevailing southwest monsoon winds in summer transporting more water from the South China Sea to the TS, and the river discharge brings more terrigenous organic matters into the TS. Therefore, the DOC export in summer is higher than in winter.

The studies of tidal current and sea level variation in the Taiwan Strait are popular topics in recent years. The sea level data, to be applied to data analysis or model forcing and validation, are mostly observed in the near shore region. It is relative not easier to obtain real tidal data in the offshore area. This study intended to obtain sea level data within Taiwan Strait, using in-situ water depth measurements collected by EK500 of research vessels OR1, OR2 and OR3 during 1989-2003. The basic assumption of this work is that the changes of sea level and topographical depth equal to observed water depth. By using a large set of field measurements, it is possible to get bottom topography such that tidal data can be extracted by harmonic analysis of long-term discrete time series of water depth data. A total of 1513 cruises of water depth data were collected, which account for nearly 6 million samples. These data were screened through a series of criteria for quality control. Firstly, data were plotted cruise by cruise ( longitude vs latitude , longitude vs depth , time vs depth), then reasonable range of time, depth and region were choosed manually. Second, outliers, defined as values greater than 3 standard deviations on 5 point moving mean along the cruise track (or time), were replaced by linear interpolation values. Finally, a 2-minute moving average was applied to the along track time series water depth data. This step was trying to remove the effect of surface waves. The original huge records were reduced to about 550,000 valuable samples for the 1513 cruises data. According to the density distribution of water depth samples in Taiwan Strait, 32 sub-region were selected for topography and harmonic analyses. In each sub-region, the bottom topography was mapped by an optimal interpolation method through a Gaussian weighting function. The radius of Gaussian weighting function applied is 3 time of the distance of grid. Water depth samples subtracted topographical depth of nearby grid to form a set of sea level data ready for harmonic analysis. The phase and amplitude of semi-diurnal tides (M2) and diurnal tides (K1¡BO1) in each sub-region were computed for the 32 regions in Taiwan Strait. The water depth measurements derived sea level variations were compatible with that of a global tidal model (OSU) and a set of moored long-term pressure records in the middle of the strait. Especially, the tidal phase among these results were quite close. However, the tidal amplitudes of water depth data derived were smaller. Sensitivity analysis showed that the errors, differences between OSU model and depth derived sea levels, were small with regions of high density of water depth measurements. Both harmonic derived sea level variations and OSU model predictions indicated a southward propagating tidal wave, which matched with the scenario of Kevin wave propagation in Taiwan Strait. Our analysis also showed that the sea level variations in the northern part of the strait were dominated by M2 and K1 components while the southern part of the strait were dominated by M2 and O1 components.

Abstract The Art of War by Sun Tzu is ¡§To know yourself and enemy, will be ever-victorious¡¨ The mainland China has always ¡§threatening by characters and militarily force to Taiwan¡¨, and emphasized ¡§ not get rid of and liberate Taiwan by militarily ¡§, can nearly confirm the mainland China regard military affair as the fundamental key of negotiation backing. It is worth noting , Many military exercises and strategy and over the years of the mainland China, analysed the report by military experts and media analysis such as , Dong-Shan Island military exercises of East China Sea, and guess the mainland China is dispatch troops the first-selected strategic objective which is attacking the Penghu(Pescadores) in recent years. Why the archipelago of Penghu is the locking goal of simulation to attack Taiwan by mainland China ? Especially the high-ranking military officer Shi Lang campaign and seized Penghu against Ching Dynasty, it was from Dong-Shan Island of the mainland China before going to war is Zheng's Dynasty strategy by force fighting to surrender too. In history experience and example, all kinds of overseas attacked of Taiwan campaigns, it took Penghu as the strategic objective. in war history, The fate between Taiwan and Penghu seems link up together and closely. what was the trick and strategy about this by mainland China? According to international strategy, the Penghu is the first island chain of Pacific Ocean while enclose and stopping up strategy by the U.S. it is one of the main pass of international crude oil channel of Taiwan Straits. the modern international war all arises because of petroleum, that China while emerging rapidly is dependent on the petroleum, has already become the second major energy-consuming country in the world, the security imported of the crude oil is increasingly day by day, the Penghu is looks like prickles down the back for China. Taiwan is the narrow and long island, extremely short of the strategic depth, the modern war has already struck the speed that the persons who defend react greatly, To ensure security of Taiwan , it must to overcome this disadvantage; In addition, The Ministry of National Defence is carrying on the withdrawing troops of Kim-Men and Ma-Zu. How to use the limited defence weapons, strive for early warning time, and resist enemy out of the territory when attacked on suddenly and frighten effective become the task of top priority of our strategic Distribution, and whether Penghu archipelago can play the key role of the leading base appropriately, It is worth to deep discussion. This research is since the instance of the war between two sides of the Taiwan Straits verifying, Commenting strategic position and worth were in the war incident of the Taiwan Straits .And Mainland China bet on all strategic phenomenon in Taiwan Straits as well as defend the essence action of strategy with Taiwan¡¦s defenses in recent years, including the influence between Taiwan and Mainland China through transport and exchange, To be necessary to discussion the change about Penghu. Hope from ancient and modern documents research, let everyone know how importance of Penghu to Taiwan, and bring up appropriate suggestions as strategic value to make the best of the Penghu from theory and science. Keyword¡GPenghu, Taiwan Strait, Cross-Strait, Strategic research, Strategic position

The dynamics of marginal seas is complex in terms of carbon dioxide absorption and release. This thesis analyzes data collected in the southern Taiwan Strait and in the South China Sea. In order to deduct the influence of temperature on the fCO2, fCO2 is normalized to the average water temperature (fCO2 mean). In the spring of 2008, in the Taiwan Strait, when salinity was smaller than approximately 33.8, measured fCO2 mean and salinity had a negative correlation; but when the salinity was higher than approximately 33.8, the correlation was positive. When salinity was smaller than apprx. 33.8, fCO2 cal. mean correlated slightly negatively to chlorophyll. This indicates that the low fCO2 cal. was not only caused by the increase of the CO2 solubility at lower temperatures, but also by the biotic photosynthesis. On the contrary, when the salinity was higher than apprx. 33.8, fCO2 cal. mean and the chlorophyll held positive correlation. It indicates that the influence of photosynthesis was reduced. In this case, the primary factor of fCO2 cal. change was due to the mixing of the high normalized dissolved inorganic carbon (NDIC=35¡ÑDIC/S) China Coastal Current with low NDIC seawater. With a raise of seawater temperature, then a decrease of the CO2 solubility, seawater became a source of carbon dioxide. In the summer of 2008, the northern South China Sea was influenced by Pearl River plume, resulting in lower fCO2 and salinity. The fCO2 of the China coast was influenced not only by the Pearl River plume, but also by the Jiulong River plume and upwelling. The Taiwan Strait water mass mainly contains the South China Sea water, a Kuroshio branch and the China Coast Current. During an El Niño year, the monsoon weakens, so that the volume of Kuroshio entering the South China Sea increases. However, for La Niña years, the monsoon strengthens, therefore the volume of the Kuroshio entering the South China Sea decreases. As a result, the Taiwan Strait water changes interannually due to different mixture of seawater of the Kuroshio and the South China Sea. The southern Taiwan Strait could be divided into the Penghu Channel and the western strait. During an El Niño summer, the Penghu Channel is occupied by waters with high temperature, salinity and pH, but low NDIC and nutrients. This is because more Kuroshio waters enter the South China Sea, then move northward to the southern Taiwan Strait. The hydrology in the Penghu Channel in normal years shows different result from season to season. In the summer, the Penghu Channel contains low temperature, salinity and pH water. In winter, waters with high salinity and pH, but low AOU, NDIC and nutrients prevail. This indicates that less Kuroshio waters enter the South China Sea in summer than in winter. The hydrology of the Penghu Channel changes decidedly from season to season in a normal year but spring, summer and fall have no clear change in the El Niño period, because more Kuroshio waters enter the South China Sea in summer. The wind effect during the El Niño period becomes weakened, have the hydrology during summer monsoon is similar to the hydrology in spring and summer. The waters of the Penghu Channel reach the highest pH, but the lowest AOU, NDIC and nutrients in winter. Older waters from upwelling move to the north in the western Strait during spring and fall in a normal year. However, during the El Niño period, possibly due to the weaker monsoon, such upwelling signal is reduced. Waters of the western strait in winter have higher temperature, salinity and pH, but lower NDIC during the El Niño period compared to a normal year. This indicates that the El Niño influences not only the Penghu Channel but also the entire southern Taiwan Strait in winter.

Methane (CH4) is not only important but also a long-lived greenhouse gas. Scientists estimated that more than half of CH4 is released from the water column. Studies of methane from water column are almost focused on rice fields, wetlands and swamps in Taiwan. There are only limited studies of methane about rivers, lakes and coasts. So this study investigated CH4 distribution in natural waters on and around Taiwan. The average surface methane concentration in the South China Sea (SCS) is about 5.10¡Ó3.61 nM (n=103). The average surface methane concentration in the West Philippines Sea (WPS) is about 3.44¡Ó3.89 nM (n=56), lower than in the SCS. The average surface concentration in the Northern and Southern Taiwan Strait are, respectively, 4.72¡Ó3.19 nM (n=64) and 4.01¡Ó3.19 nM (n=51), and are between the average concentrations in the SCS and the WPS. The sea-to-air fluxes of methane in the SCS and the WPS are 0.38¡Ó0.99 £gmol/m2/h (n=103) and £gmol/m2/h (n=56), respectively. The sea-to-air fluxes of methane in the Northern and Southern Taiwan Strait are, respectively, 0.37¡Ó0.55 £gmol/m2/h (n=64) and 0.10¡Ó0.53 £gmol/m2/h (n=51). Although the sea-to-air fluxes for methane is much lower than the flux for carbon dioxide, methane emission in the SCS contributes nearly the same greenhouse effect as carbon dioxide does. In Taiwan, the average surface methane concentration in rivers is about 3221¡Ó12386 nM, and the emission is about 104¡Ó337 (£gmol/m2/h) (n=179). The average surface methane concentration and flux are, respectively, 2164¡Ó5432 nM and 265¡Ó1289 £gmol/m2/h (n=120) in the water column in China, including the coasts of Hong Kong , Pearl River and Yangtze River. The average surface methane concentration and flux in the natural water are higher than in Taiwan. In Asia, the average surface methane concentrations of the natural waters are, respectively, 8240¡Ó22753 nM (n=27) and 7639¡Ó24554 nM (n=50) in Thailand and Indonesia, twice the concentration in Taiwan. The average surface methane concentrations of the natural waters are, respectively, 2841¡Ó3358 nM (n=5) and 1939¡Ó3694 nM (n=15) in Malaysia and the Philippines, lower than in Taiwan. The emissions of methane in the natural waters are, respectively, 845¡Ó2622 £gmol/m2/h (n=50), 292¡Ó341 £gmol/m2/h (n=5) and 181¡Ó356 £gmol/m2/h (n=15) in Indonesia, Malaysia and the Philippines, also much higher than in Taiwan. The flux of methane in natural waters in Thailand (100¡Ó265 £gmol/m2/h, n=25) is as the same as in Taiwan.

The purpose of this study was to discuss the CO2 variation in and around the South China Sea (SCS), the largest marginal sea in the world. The SCS and Sulu Sea (SS) in November and December respectively, were a small CO2 source to the atmosphere. The West Philippine Sea (WPS) was a large CO2 source to the atmosphere in September. Due to strong upwelling and mixing in the SCS, the excess CO2 penetrated only to approximately 1000m compared to 1200m in the WPS. Because the SCS subsurface water flows to the SS through the 420 m-deep Mindoro Strait, the excess CO2 in the SS was found throughout the entire water column. According to NOAA, 2002 was a weak-to-moderate strength ENSO year and the second warmest since 1986. The Taiwan Strait is the sole passage which connects the East and South China Seas, but the CO2 variation in the Taiwan Strait is unclear during the ENSO year. We heady discuss the relation between the ENSO and CO2 variation in the Taiwan Strait. During the ENSO year, the Penghu Channel mixed in more Kuroshio water but the upwelling strength weakened. During an ENSO event, the southwest monsoon and surface circulation are weaker than normal, hence there is less SCS water flowing to the Penghu Channel. Primary productivity in the non-ENSO year (2001) was high so the fCO2 was low in the upwelling area in the Penghu Channel. The £G fCO2(sea-air) was about 15&#x00B5;atm and 20&#x00B5;atm in the non-ENSO year and the ENSO year, respectively. The southern Taiwan Strait was a source of CO2 in summer. The hydrology in the northern Taiwan Strait in summer was comprised mainly of two different water masses. A salinity front was found at between 25.67oN, 121.24oE and 25.87oN, 120.95oE in the non-ENSO year and at between 25.67oN, 121.24oE and 25.77oN, 121.08oE in the ENSO year. There was coastal upwelling in the western Taiwan Strait in the ENSO year. In the ENSO year, the southward flowing China Coastal Current in winter (January to March) was weaker than normal, which led to a higher percentage of northward flowing water mass in summer. As a result, the summer time salinity in the surface layer became higher so the vertical density gradient became lower than a normal year. East of the front was the Kuroshio and west of the front was the water mass that flew through the Taiwan Strait. The Kuroshio is high in temperature and salinity so the fCO2 to the east of the front was higher than found west of the front in the non-ENSO year. In the ENSO year, owing to the coastal upwelling, the fCO2 near the Chinese coast was higher than east of the front. The northern Taiwan Strait had a £G fCO2(sea-air) of about 21&#x00B5;atm and 16&#x00B5;atm in the non-ENSO and the ENSO years, respectively, and it was still a source of CO2 in summer.

The features of upwelled water are cold, salty and nutrient-rich. However, factors such as the air-sea exchanges of heat affect temperature, and freshwater input from rivers, precipitation and evaporation affect salinity. As biologically important elements are mostly in the dissolved inorganic forms in young upwelled waters, and are mostly in the particulate organic forms in old upwelled waters, the aging status of upwelled waters can be expressed as the relative percentages of biologically important elements in the inorganic and organic forms. Further, nutrients may be consumed by biological productivity. For these reasons, we hereby judge upwelling in the Taiwan Strait (TS) between 2000 and 2002 by the Degree of Nutrient Consumption (DNC, DNCC = and DNCX = ¡AX is nitrogen or phosphorus). The value of DNC is low in young upwelled waters but high in old upwelled waters. In summer, autumn and winter, waters at, or east of, a front in the northeastern Taiwan Strait were affected by the Kuroshio off eastern Taiwan. This front divides the Kuroshio water, the South China Sea (SCS) water that flows through the TS and the Coastal China Current water (in winter). The implications are that not all currents in the Taiwan Strait flow in a northerly direction, even in summer. Because the axis of Kuroshio moved away from eastern Taiwan and upwelling weakened in SCS in 2002, salinity east of the front was fresher, and nutrient and DON were lower in 2002 than 2001. On the other hand, upwelling induced higher DON west of the front. In August, 2002, the water in the southern TS was higher in temperature, more salty, but nutrient and DON were lower than in 2001 because of weakened upwelling in the SCS, and water that intruded into the TS had a higher percentage of Kuorshio. The trend of upwelling, DNCC,P,N was along the west Penghu Channel from bottom to surface. Rates of temperature, salinity and DNCC,P,N variation were greater during 2001 than in 2002, reflecting slower rate of upwelling in 2002.

In the design and plan of the coast engineering, long-term and continual tidal database represent the indispensable role. This paper collect the tidal database, their locations include the ocean around the Taiwan and the South China Sea. Use the artificial neural networks (ANN) to build model and find the relationship between neighbor tidal observation stations. There are many reasons to cause the tide phenomenon, include the tide generating force, season, coastal geography, geography of sea floor, resonance of gulf or estuary, change depth of sea, and so on, it will be determined by local environment. The tide analysis and prediction usually use the harmonic analysis method. This method need long-term and continual tidal record, and the theory depend on the tide generating force, it has limit about accuracy. The application of artificial neural networks is used in nonlinear science problems in general cases. The back propagation (BP) networks is the one model of the artificial neural networks, this paper use ANN-BP model to build the relationship from different tide observed stations, and verify the quality of model. From the result of verified models, the ANN-BP model can predict and supplement the tide record very well. The items of research include: ¡i1¡j the relationship between two neighbor tide observed stations. (one station input, one station output) ¡i2¡jthe relationship between three neighbor tide observed stations. (two station input, one station output) ¡i3¡j input several tide observed stations and output one station. ¡i4¡j the correlation of connected weight and threshold between different models. ¡i5¡j change the parameters of ANN-BP model and discus the affect of model¡¦s quality. ¡i6¡j application of truly case. From the result of this paper, in the design and plan of the coast engineering, the long-term tide observed record can be predict from the ANN-BP model and tide record of neighbor observed stations. When the tide record has miss or lost cause by machine or other reasons, the ANN-BP model can supplement the lost tide record well. This paper show the ANN-BP model can be apply to predict and supplement the tide record very well, and will be possible applied method.

This study utilized, for the first time, the d18Osw as a tracer to investigate the seasonal variations of circulation in the Taiwan Strait (TS), which is the predominant sea passage with an average depth of 60 m connecting the East China Sea (ECS) and the South China Sea (SCS). The result shows that the circulation system in TS is mainly influenced by the inter-mixing among the China Coastal Water (CCW), the SCS water (SCSW), and the Kuroshio Water (KW). In spring, the KW dominates in TS, whereas the CCW is still observed in northwest TS. During the summer, SCSW replaces the KW and becomes the major water type in the TS, yet the KW is found to be restricted in the southwest part and the bottom of the TS. Due to the larger discharge from rivers (mainly the Yangtz River), the CCW has a more extensive distribution in the TS in summer than other seasons. In fall and winter, the CCW occupies the northern part of TS due to the stronger northeastern monsoon which limits the intrusion of the KW through the Luzon Strait to the northern TS. The two distinct water types inevitably form a front in the central TS. The hydrographic variations at Penghu Channel (PHC) were also explored in this study. The d18Osw indicates that the perennial intrusion of the KW into the PHC is varying throughout different seasons. This intrusion is found strongest in fall and winter. In summer, the upper layer of PHC is occupied chiefly by SCSW, while the KW remains at the bottom layer in PHC. By including an additional inflow of 0.5Sv from TS to ECS, this study further reconstructed a box model of the ECS, which was previously furnished by Lin(1999). The new estimates suggest that ~0.38*104 km3/year of the Kuroshio surface water (0-50m) and ~1.54*104 km3/year of the upwelled Kuroshio subsurface water (50-150m) are transported to the ECS, while ~3.83*104 km3/year of the ECS water are exported to the western Pacific Ocean.

El Ni&#x00F1;o is now a focal point for global climate change research, but its influence on the Western Pacific is still uncertain. Taiwan Strait is an important pathway, which connects the South China Sea and the East China Sea, and is strongly influenced by the monsoon. Generally, in winter, the strong winter monsoon brings the cold and nutrient-rich Changjiang Diluted Water¡]CDW¡^southward. While during the El Ni&#x00F1;o event, because of the weakened south wind in northern Taiwan, more cold CDW moves southward, and hence the decreased seawater temperature in spring and fall. The trend is opposite in summer. There is a high salinity signal in the seas outside of Hsin-Chu, suggesting sea water coming from the Kuroshio, which has circumvented the northeast tip of Taiwan. Meanwhile, there is a front which separates this Kuroshio water and CDW. During the El Ni&#x00F1;o, the front moves eastward, especially in summer. The salinity east of the front decreases gradually from spring to winter water, the center of upwelling located at the eastern side of the front in spring, and at or near the front from summer to winter. Furthermore, The N/P ratio of the northern Taiwan Strait water became higher after the Three Gorges Dam (TGD) became operational. The nitrous oxide (N2O) is a long-lived greenhouse gas. Unfortunately, in Taiwan, there are few data about N2O emission from rivers, lakes and coastal areas. This research also studies the N2O distribution in natural waters around Taiwan. The average surface water concentration and sea to air flux in the Taiwan Strait¡]7.81¡Ó1.28nM¡F0.28¡Ó0.38£gmol/m2/hr¡^is higher than in the South China Sea¡]SCS¡F7.55¡Ó2.45 nM¡F0.21¡Ó0.27£gmol/m2/hr¡^and the West Philippine Sea¡]WPS¡F5.3¡Ó0.62nM¡F-0.20¡Ó0.25£gmol/m2/hr¡^, which displays a rare sink signal in the world oceans. There is an N2O maximum observed around 1000m in the WPS, and another shollower one around 700m in the SCS, presumably because of the intenive upwelling and vertical mixing in the SCS basin. There are some rather high N2O concentrations (N2O>30nM) in the SCS, observed near the continental slope. We assume that these are released from sediments on the continental slope. Although the sea-to-air flux of N2O is much lower than the flux of CO2, N2O emission in the SCS contributes more than two times the greenhouse effect than CO2 does. Besides, The N2O concentration during El Ni&#x00F1;o is lower than usual, probably due to a smaller amount of the CDW. Finally, the average N2O concentrations of river and submarine groundwater discharge in Taiwan are about 32.3¡Ó43.3nM and 9.72¡Ó13.2 nM, respectively.