Wen-Zhou Zhang - Academia.edu (original) (raw)

Papers by Wen-Zhou Zhang

Research paper thumbnail of Influence of Tropical Cyclones in the Western North Pacific

Recent Developments in Tropical Cyclone Dynamics, Prediction, and Detection, 2016

The Western North Pacific (WNP) is the most favorable area in the world for the generation of tro... more The Western North Pacific (WNP) is the most favorable area in the world for the generation of tropical cyclones (TCs). As the most intense weather system, TCs play an important role in the change of ocean environment in the WNP. Based on many investigations published in the literature, we obtained a collective and systematic understanding of the influence of TCs on ocean components in the WNP, including sea temperature, ocean currents, mesoscale eddies, storm surges, phytoplankton (indicated by chlorophyll a). Some ocean responses to TCs are unique in the WNP because of the existence of the Kuroshio and special geographical configurations such as the South China Sea.

Research paper thumbnail of Physical drivers of chlorophyll variability in the open South China Sea

Journal of Geophysical Research: Oceans, 2016

The variability of chlorophyll a concentration (Chl a) in the open South China Sea (SCS) was exam... more The variability of chlorophyll a concentration (Chl a) in the open South China Sea (SCS) was examined using observations from two Bio-Argo floats. During the period of September 2014 to August 2015, there was a permanent subsurface Chl a maximum (SCM) in the depth range of 48 to 96 m in the central basin of the SCS. In the northern basin, the SCM disappeared in winter, replaced by enhanced surface layer phytoplankton with high Chl a. The values of the SCM were influenced by the vertical displacement of isotherms. Strong wind forcing and surface cooling were the main physical drivers of high surface Chl a in winter. In the north, stronger wind than in the center, lower sea surface temperature (SST) than in the center, and Kuroshio water intrusion were more favorable for the upward transport of nutrient-rich deep water. A large amount of nitrate could be advected from the Taiwan Strait and shallow continental shelf to the northern basin in winter. A combination of strong wind mixing, surface cooling, Kuroshio water intrusion, and horizontal advection caused the winter surface phytoplankton bloom in the north.

Research paper thumbnail of Volume transport through the Taiwan Strait and the effect of synoptic events

Continental Shelf Research, 2014

Volume transport through the Taiwan Strait during 2005-2008 was simulated using a shallow water m... more Volume transport through the Taiwan Strait during 2005-2008 was simulated using a shallow water model forced by high spatio-temporal resolution meteorological data. On average, simulated monthly mean transports ranged from a southward maximum of 0.38 Sv in December to a northward maximum of 2.02 Sv in June, with an annual mean northward transport of 0.78 Sv. These estimates are in agreement with the published results based on bottom-mounted ADCP observations. Several sensitivity experiments were conducted to separately examine possible influence of ignoring air pressure or applying time-averaged wind forcing on the transport estimate. We found that excluding the air pressure component in the model gave rise to an insignificant difference (0.01 Sv) in the mean transport estimate. Using multi-year-averaged monthly mean wind, however, provided markedly different results; it brought about a magnitude change of up to 0.65 Sv for the monthly mean transport and 0.34 Sv for the annual mean transport. The nonlinear parameterization of wind stress was mainly responsible for the distortion. In addition, we found that typhoons, as one kind of synoptic events, had an accumulative influence not only on the monthly mean transport during the typhoon season but also on the annual mean transport. The effect of typhoons reduced the monthly mean transport by up to 0.45 Sv and the annual mean transport by 0.09 Sv (more than 10%). Therefore, high temporal resolution wind data with synoptic scale variability are required to accurately estimate the monthly mean and annual mean transports when using a model.

Research paper thumbnail of Strong southward transport events due to typhoons in the Taiwan Strait

Journal of Geophysical Research: Oceans, 2009

Transport through the Taiwan Strait under the influence of five typhoons was investigated using b... more Transport through the Taiwan Strait under the influence of five typhoons was investigated using both buoy observations and numerical model simulations during the period of 27 August to 5 October 2005. The results show that the effects of typhoons on the Taiwan Strait and its adjacent sea area caused strong southward transport events in the Taiwan Strait, which changed the direction of the Taiwan Strait northward transport temporarily. Typhoon‐generated local wind stress and/or along‐strait water level gradient were the direct driving factors in these southward transport events. The numerical results show that the Coriolis force made a negative contribution to these events and the contribution of the along‐strait momentum gradient was insignificant.

Research paper thumbnail of Typhoons enhancing northward transport through the Taiwan Strait

Continental Shelf Research, 2013

Volume transport in the Taiwan Strait is usually northward for most of the year and varies season... more Volume transport in the Taiwan Strait is usually northward for most of the year and varies seasonally because of the adjustment of the East Asian monsoon. Based on model simulations, the influence on this northward transport of every typhoon formed during the period 2005-2009 was examined. The results showed that there were four typhoons which enhanced northward transport during these five years. The current measurements, obtained from a buoy deployed in the Taiwan Strait, matched these events exactly. These typhoons had special moving tracks and life histories. They traveled westward in the area south of the strait or moved northward from the south to the north. Under the influence of such a typhoon, the prophase southward atmospheric forcing in the strait was weak and the anaphase northward atmospheric forcing (mainly along-strait wind stress) was strong, which is necessary and crucial in enhancing the northward transport. The ageostrophic process, another important driving factor in transport change, was generated mainly by local atmospheric forces inside the strait under the typhoon weather conditions and its effect on transport magnitude was comparable to that of direct atmospheric forcing. It first stored some energy from the atmospheric forcing to restrain the transport change, and then released the stored energy to prolong and even to intensify the enhanced northward transport.

Research paper thumbnail of Varying intensity of Kuroshio intrusion into Southeast Taiwan Strait during ENSO events

Continental Shelf Research, 2015

The Taiwan Strait is the only direct passage between the South China Sea (SCS) and the East China... more The Taiwan Strait is the only direct passage between the South China Sea (SCS) and the East China Sea. Variations in the intensity of Kuroshio Branch and surface currents in the SCS result in seasonal and interannual variability in the hydrography of the SE Taiwan Strait, where the northwardly pointing funnel-like Penghu Channel is located. These currents vary with the intensity and direction of monsoons. The teleconnection between air-sea interaction of the east Pacific and west Pacific reportedly has time differences. The data in this study reveal that the salinity of the seawater in the Penghu Channel is highest during El Niño events with a seven-month lag to the monthly Niño 3.4 index, and lowest during La Niña periods, also with a lag of seven months to the monthly Niño 3.4 index. The chemical parameters also vary with these events. The concentrations of apparent oxygen utilization, nutrients, and hydrogen ions vary with the mixing ratio of SCS water and Kuroshio Branch water. The maximum concentrations of nutrients are significantly higher during the summer, seven months after a La Niña event (La Niña-7), than in other seasons. However, biological activities also affected these chemical parameters. In spring, active photosynthesis consumes more nutrients and hydrogen ion concentrations in La Niña-7 periods than in normal-7 periods.

Research paper thumbnail of Numerical study on tides in the Taiwan Strait and its adjacent areas

… of Oceanography in …, 2007

Diurnal and semi-diurnal tides in the Taiwan Strait and its adjacent areas are calculated by usin... more Diurnal and semi-diurnal tides in the Taiwan Strait and its adjacent areas are calculated by using a two-dimensional finite-difference model. Compared with data of more than 20 observation stations around the Taiwan Strait, the model-produced results agree quite well with those of previous researches using observational data from coastal tidal gauge stations. According to the results, the co-tidal and co-range charts are given. Furthermore, the characteristics of 8 major tidal constituents have been illuminated respectively. The result shows that: (1) The tide motion can be attributed to the interaction between the degenerative rotary tidal system in the north and the progressive tidal system in the south. (2) The southward and northward tidal waves of semi-diurnal tide converge in the middle of the Taiwan Strait while the diurnal tidal waves propagate southwestward through the Taiwan Strait and the Luzon Strait. (3) The maximum amplitude of semi-diurnal tides exists at the area between the Meizhou Bay and Xinghua Bay, and that of diurnal tides appears in the region to the east of the Leizhou Peninsula. (4) The patterns of co-tidal and co-range charts of N 2 , K 2 and P 1 , Q 1 tidal constituents are similar to those of M 2 , S 2 and K 1 , O 1 tidal constituents, respectively.

Research paper thumbnail of A two-way nested coupled tide-surge model for the Taiwan Strait

Continental Shelf Research, 2007

A two-way nested coupled tide-surge prediction model was established and applied in the Taiwan St... more A two-way nested coupled tide-surge prediction model was established and applied in the Taiwan Strait and adjacent sea area in this study. This two-dimensional (2D) model had a fine horizontal resolution and took into account the interaction between storm surges and astronomical tides, which made it suitable for depicting the complicated physical properties of storm surges in the Taiwan Strait. A two-way nesting technique and an open boundary condition developed from Flather's radiation condition and Røed and Smedstad's local mode idea, were successfully implemented in the model. A simulation experiment showed that the open boundary condition could be used in the coupled tide-surge model and that the performance of the two-way nested model was slightly superior in accuracy to that of the one-way nested one. The fluctuations of storm surge residuals with tidal period at Sansha and Pingtan tide stations during the period of typhoon Dan in 1999 were well reproduced by the model, with the coupling effect between storm surges and tides indicating that the effect of astronomical tides upon typhoon surges should be considered in a storm-surge prediction model for the Taiwan Strait. The forecast experiment during typhoon Talim in 2005 showed that the storm surge prediction outputs by the model were better in the early 20 h of the forecast period of each model run than those in the later period due to the prediction accuracy of the typhoon track, maximum winds, and central air pressures.

Research paper thumbnail of Tide-surge Interaction Intensified by the Taiwan Strait

Journal of Geophysical Research, 2010

The Taiwan Strait is a long and wide shelf-channel where the hydrodynamics is extremely complex, ... more The Taiwan Strait is a long and wide shelf-channel where the hydrodynamics is extremely complex, being characterized by strong tides, and where storm surges frequently occur during the typhoon season. Obvious oscillations due to tide-surge interaction were observed by tide gauges along the northern Fujian coast, the west bank of the Taiwan Strait, during Typhoon Dan (1999). Numerical experiments indicate that nonlinear bottom friction (described by the quadratic formula) is a major factor to predict these oscillations while the nonlinear advective terms and the shallow water effect have little contribution. It is found that the tide-surge interaction in the northern portion of the Taiwan Strait is intensified by the strait. Simulations based on simplified topographies with and without the island of Taiwan show that, in the presence of the island, the channel effect strengthens tidal currents and tends to align the major axes of tidal ellipses along the channel direction. Storm-induced currents are also strengthened by the channel. The pattern of strong tidal currents and storminduced currents along the channel direction enhances tide-surge interaction via the nonlinear bottom friction, resulting in the obvious oscillations along the northern Fujian coast.

Research paper thumbnail of Upper ocean response to tropical cyclones: a review

Geoscience Letters

Tropical cyclones (TCs) are strong natural hazards that are important for local and global air–se... more Tropical cyclones (TCs) are strong natural hazards that are important for local and global air–sea interactions. This manuscript briefly reviews the knowledge about the upper ocean responses to TCs, including the current, surface wave, temperature, salinity and biological responses. TCs usually cause upper ocean near-inertial currents, increase strong surface waves, cool the surface ocean, warm subsurface ocean, increase sea surface salinity and decrease subsurface salinity, causing plankton blooms. The upper ocean response to TCs is controlled by TC-induced mixing, advection and surface flux, which usually bias to the right (left) side of the TC track in the Northern (Southern) Hemisphere. The upper ocean response usually recovers in several days to several weeks. The characteristics of the upper ocean response mainly depend on the TC parameters (e.g. TC intensity, translation speed and size) and environmental parameters (e.g. ocean stratification and eddies). In recent decades, ou...

Research paper thumbnail of Strong southward transport events due to typhoons in the Taiwan Strait

Journal of Geophysical Research, 2009

1] Transport through the Taiwan Strait under the influence of five typhoons was investigated usin... more 1] Transport through the Taiwan Strait under the influence of five typhoons was investigated using both buoy observations and numerical model simulations during the period of 27 August to 5 October 2005. The results show that the effects of typhoons on the Taiwan Strait and its adjacent sea area caused strong southward transport events in the Taiwan Strait, which changed the direction of the Taiwan Strait northward transport temporarily. Typhoon-generated local wind stress and/or along-strait water level gradient were the direct driving factors in these southward transport events. The numerical results show that the Coriolis force made a negative contribution to these events and the contribution of the along-strait momentum gradient was insignificant.

Research paper thumbnail of Tide-surge Interaction Intensified by the Taiwan Strait

Journal of Geophysical Research, 2010

1] The Taiwan Strait is a long and wide shelf-channel where the hydrodynamics is extremely comple... more 1] The Taiwan Strait is a long and wide shelf-channel where the hydrodynamics is extremely complex, being characterized by strong tides, and where storm surges frequently occur during the typhoon season. Obvious oscillations due to tide-surge interaction were observed by tide gauges along the northern Fujian coast, the west bank of the Taiwan Strait, during Typhoon Dan (1999). Numerical experiments indicate that nonlinear bottom friction (described by the quadratic formula) is a major factor to predict these oscillations while the nonlinear advective terms and the shallow water effect have little contribution. It is found that the tide-surge interaction in the northern portion of the Taiwan Strait is intensified by the strait. Simulations based on simplified topographies with and without the island of Taiwan show that, in the presence of the island, the channel effect strengthens tidal currents and tends to align the major axes of tidal ellipses along the channel direction. Storm-induced currents are also strengthened by the channel. The pattern of strong tidal currents and storminduced currents along the channel direction enhances tide-surge interaction via the nonlinear bottom friction, resulting in the obvious oscillations along the northern Fujian coast.

Research paper thumbnail of Strong southward transport events due to typhoons in the Taiwan Strait

Journal of Geophysical Research, 2009

1] Transport through the Taiwan Strait under the influence of five typhoons was investigated usin... more 1] Transport through the Taiwan Strait under the influence of five typhoons was investigated using both buoy observations and numerical model simulations during the period of 27 August to 5 October 2005. The results show that the effects of typhoons on the Taiwan Strait and its adjacent sea area caused strong southward transport events in the Taiwan Strait, which changed the direction of the Taiwan Strait northward transport temporarily. Typhoon-generated local wind stress and/or along-strait water level gradient were the direct driving factors in these southward transport events. The numerical results show that the Coriolis force made a negative contribution to these events and the contribution of the along-strait momentum gradient was insignificant.

Research paper thumbnail of A two-way nested coupled tide-surge model for the Taiwan Strait

Continental Shelf Research, 2007

A two-way nested coupled tide-surge prediction model was established and applied in the Taiwan St... more A two-way nested coupled tide-surge prediction model was established and applied in the Taiwan Strait and adjacent sea area in this study. This two-dimensional (2D) model had a fine horizontal resolution and took into account the interaction between storm surges and astronomical tides, which made it suitable for depicting the complicated physical properties of storm surges in the Taiwan Strait. A two-way nesting technique and an open boundary condition developed from Flather's radiation condition and Røed and Smedstad's local mode idea, were successfully implemented in the model. A simulation experiment showed that the open boundary condition could be used in the coupled tide-surge model and that the performance of the two-way nested model was slightly superior in accuracy to that of the one-way nested one.

Research paper thumbnail of Influence of Tropical Cyclones in the Western North Pacific

Recent Developments in Tropical Cyclone Dynamics, Prediction, and Detection, 2016

The Western North Pacific (WNP) is the most favorable area in the world for the generation of tro... more The Western North Pacific (WNP) is the most favorable area in the world for the generation of tropical cyclones (TCs). As the most intense weather system, TCs play an important role in the change of ocean environment in the WNP. Based on many investigations published in the literature, we obtained a collective and systematic understanding of the influence of TCs on ocean components in the WNP, including sea temperature, ocean currents, mesoscale eddies, storm surges, phytoplankton (indicated by chlorophyll a). Some ocean responses to TCs are unique in the WNP because of the existence of the Kuroshio and special geographical configurations such as the South China Sea.

Research paper thumbnail of Physical drivers of chlorophyll variability in the open South China Sea

Journal of Geophysical Research: Oceans, 2016

The variability of chlorophyll a concentration (Chl a) in the open South China Sea (SCS) was exam... more The variability of chlorophyll a concentration (Chl a) in the open South China Sea (SCS) was examined using observations from two Bio-Argo floats. During the period of September 2014 to August 2015, there was a permanent subsurface Chl a maximum (SCM) in the depth range of 48 to 96 m in the central basin of the SCS. In the northern basin, the SCM disappeared in winter, replaced by enhanced surface layer phytoplankton with high Chl a. The values of the SCM were influenced by the vertical displacement of isotherms. Strong wind forcing and surface cooling were the main physical drivers of high surface Chl a in winter. In the north, stronger wind than in the center, lower sea surface temperature (SST) than in the center, and Kuroshio water intrusion were more favorable for the upward transport of nutrient-rich deep water. A large amount of nitrate could be advected from the Taiwan Strait and shallow continental shelf to the northern basin in winter. A combination of strong wind mixing, surface cooling, Kuroshio water intrusion, and horizontal advection caused the winter surface phytoplankton bloom in the north.

Research paper thumbnail of Volume transport through the Taiwan Strait and the effect of synoptic events

Continental Shelf Research, 2014

Volume transport through the Taiwan Strait during 2005-2008 was simulated using a shallow water m... more Volume transport through the Taiwan Strait during 2005-2008 was simulated using a shallow water model forced by high spatio-temporal resolution meteorological data. On average, simulated monthly mean transports ranged from a southward maximum of 0.38 Sv in December to a northward maximum of 2.02 Sv in June, with an annual mean northward transport of 0.78 Sv. These estimates are in agreement with the published results based on bottom-mounted ADCP observations. Several sensitivity experiments were conducted to separately examine possible influence of ignoring air pressure or applying time-averaged wind forcing on the transport estimate. We found that excluding the air pressure component in the model gave rise to an insignificant difference (0.01 Sv) in the mean transport estimate. Using multi-year-averaged monthly mean wind, however, provided markedly different results; it brought about a magnitude change of up to 0.65 Sv for the monthly mean transport and 0.34 Sv for the annual mean transport. The nonlinear parameterization of wind stress was mainly responsible for the distortion. In addition, we found that typhoons, as one kind of synoptic events, had an accumulative influence not only on the monthly mean transport during the typhoon season but also on the annual mean transport. The effect of typhoons reduced the monthly mean transport by up to 0.45 Sv and the annual mean transport by 0.09 Sv (more than 10%). Therefore, high temporal resolution wind data with synoptic scale variability are required to accurately estimate the monthly mean and annual mean transports when using a model.

Research paper thumbnail of Strong southward transport events due to typhoons in the Taiwan Strait

Journal of Geophysical Research: Oceans, 2009

Transport through the Taiwan Strait under the influence of five typhoons was investigated using b... more Transport through the Taiwan Strait under the influence of five typhoons was investigated using both buoy observations and numerical model simulations during the period of 27 August to 5 October 2005. The results show that the effects of typhoons on the Taiwan Strait and its adjacent sea area caused strong southward transport events in the Taiwan Strait, which changed the direction of the Taiwan Strait northward transport temporarily. Typhoon‐generated local wind stress and/or along‐strait water level gradient were the direct driving factors in these southward transport events. The numerical results show that the Coriolis force made a negative contribution to these events and the contribution of the along‐strait momentum gradient was insignificant.

Research paper thumbnail of Typhoons enhancing northward transport through the Taiwan Strait

Continental Shelf Research, 2013

Volume transport in the Taiwan Strait is usually northward for most of the year and varies season... more Volume transport in the Taiwan Strait is usually northward for most of the year and varies seasonally because of the adjustment of the East Asian monsoon. Based on model simulations, the influence on this northward transport of every typhoon formed during the period 2005-2009 was examined. The results showed that there were four typhoons which enhanced northward transport during these five years. The current measurements, obtained from a buoy deployed in the Taiwan Strait, matched these events exactly. These typhoons had special moving tracks and life histories. They traveled westward in the area south of the strait or moved northward from the south to the north. Under the influence of such a typhoon, the prophase southward atmospheric forcing in the strait was weak and the anaphase northward atmospheric forcing (mainly along-strait wind stress) was strong, which is necessary and crucial in enhancing the northward transport. The ageostrophic process, another important driving factor in transport change, was generated mainly by local atmospheric forces inside the strait under the typhoon weather conditions and its effect on transport magnitude was comparable to that of direct atmospheric forcing. It first stored some energy from the atmospheric forcing to restrain the transport change, and then released the stored energy to prolong and even to intensify the enhanced northward transport.

Research paper thumbnail of Varying intensity of Kuroshio intrusion into Southeast Taiwan Strait during ENSO events

Continental Shelf Research, 2015

The Taiwan Strait is the only direct passage between the South China Sea (SCS) and the East China... more The Taiwan Strait is the only direct passage between the South China Sea (SCS) and the East China Sea. Variations in the intensity of Kuroshio Branch and surface currents in the SCS result in seasonal and interannual variability in the hydrography of the SE Taiwan Strait, where the northwardly pointing funnel-like Penghu Channel is located. These currents vary with the intensity and direction of monsoons. The teleconnection between air-sea interaction of the east Pacific and west Pacific reportedly has time differences. The data in this study reveal that the salinity of the seawater in the Penghu Channel is highest during El Niño events with a seven-month lag to the monthly Niño 3.4 index, and lowest during La Niña periods, also with a lag of seven months to the monthly Niño 3.4 index. The chemical parameters also vary with these events. The concentrations of apparent oxygen utilization, nutrients, and hydrogen ions vary with the mixing ratio of SCS water and Kuroshio Branch water. The maximum concentrations of nutrients are significantly higher during the summer, seven months after a La Niña event (La Niña-7), than in other seasons. However, biological activities also affected these chemical parameters. In spring, active photosynthesis consumes more nutrients and hydrogen ion concentrations in La Niña-7 periods than in normal-7 periods.

Research paper thumbnail of Numerical study on tides in the Taiwan Strait and its adjacent areas

… of Oceanography in …, 2007

Diurnal and semi-diurnal tides in the Taiwan Strait and its adjacent areas are calculated by usin... more Diurnal and semi-diurnal tides in the Taiwan Strait and its adjacent areas are calculated by using a two-dimensional finite-difference model. Compared with data of more than 20 observation stations around the Taiwan Strait, the model-produced results agree quite well with those of previous researches using observational data from coastal tidal gauge stations. According to the results, the co-tidal and co-range charts are given. Furthermore, the characteristics of 8 major tidal constituents have been illuminated respectively. The result shows that: (1) The tide motion can be attributed to the interaction between the degenerative rotary tidal system in the north and the progressive tidal system in the south. (2) The southward and northward tidal waves of semi-diurnal tide converge in the middle of the Taiwan Strait while the diurnal tidal waves propagate southwestward through the Taiwan Strait and the Luzon Strait. (3) The maximum amplitude of semi-diurnal tides exists at the area between the Meizhou Bay and Xinghua Bay, and that of diurnal tides appears in the region to the east of the Leizhou Peninsula. (4) The patterns of co-tidal and co-range charts of N 2 , K 2 and P 1 , Q 1 tidal constituents are similar to those of M 2 , S 2 and K 1 , O 1 tidal constituents, respectively.

Research paper thumbnail of A two-way nested coupled tide-surge model for the Taiwan Strait

Continental Shelf Research, 2007

A two-way nested coupled tide-surge prediction model was established and applied in the Taiwan St... more A two-way nested coupled tide-surge prediction model was established and applied in the Taiwan Strait and adjacent sea area in this study. This two-dimensional (2D) model had a fine horizontal resolution and took into account the interaction between storm surges and astronomical tides, which made it suitable for depicting the complicated physical properties of storm surges in the Taiwan Strait. A two-way nesting technique and an open boundary condition developed from Flather's radiation condition and Røed and Smedstad's local mode idea, were successfully implemented in the model. A simulation experiment showed that the open boundary condition could be used in the coupled tide-surge model and that the performance of the two-way nested model was slightly superior in accuracy to that of the one-way nested one. The fluctuations of storm surge residuals with tidal period at Sansha and Pingtan tide stations during the period of typhoon Dan in 1999 were well reproduced by the model, with the coupling effect between storm surges and tides indicating that the effect of astronomical tides upon typhoon surges should be considered in a storm-surge prediction model for the Taiwan Strait. The forecast experiment during typhoon Talim in 2005 showed that the storm surge prediction outputs by the model were better in the early 20 h of the forecast period of each model run than those in the later period due to the prediction accuracy of the typhoon track, maximum winds, and central air pressures.

Research paper thumbnail of Tide-surge Interaction Intensified by the Taiwan Strait

Journal of Geophysical Research, 2010

The Taiwan Strait is a long and wide shelf-channel where the hydrodynamics is extremely complex, ... more The Taiwan Strait is a long and wide shelf-channel where the hydrodynamics is extremely complex, being characterized by strong tides, and where storm surges frequently occur during the typhoon season. Obvious oscillations due to tide-surge interaction were observed by tide gauges along the northern Fujian coast, the west bank of the Taiwan Strait, during Typhoon Dan (1999). Numerical experiments indicate that nonlinear bottom friction (described by the quadratic formula) is a major factor to predict these oscillations while the nonlinear advective terms and the shallow water effect have little contribution. It is found that the tide-surge interaction in the northern portion of the Taiwan Strait is intensified by the strait. Simulations based on simplified topographies with and without the island of Taiwan show that, in the presence of the island, the channel effect strengthens tidal currents and tends to align the major axes of tidal ellipses along the channel direction. Storm-induced currents are also strengthened by the channel. The pattern of strong tidal currents and storminduced currents along the channel direction enhances tide-surge interaction via the nonlinear bottom friction, resulting in the obvious oscillations along the northern Fujian coast.

Research paper thumbnail of Upper ocean response to tropical cyclones: a review

Geoscience Letters

Tropical cyclones (TCs) are strong natural hazards that are important for local and global air–se... more Tropical cyclones (TCs) are strong natural hazards that are important for local and global air–sea interactions. This manuscript briefly reviews the knowledge about the upper ocean responses to TCs, including the current, surface wave, temperature, salinity and biological responses. TCs usually cause upper ocean near-inertial currents, increase strong surface waves, cool the surface ocean, warm subsurface ocean, increase sea surface salinity and decrease subsurface salinity, causing plankton blooms. The upper ocean response to TCs is controlled by TC-induced mixing, advection and surface flux, which usually bias to the right (left) side of the TC track in the Northern (Southern) Hemisphere. The upper ocean response usually recovers in several days to several weeks. The characteristics of the upper ocean response mainly depend on the TC parameters (e.g. TC intensity, translation speed and size) and environmental parameters (e.g. ocean stratification and eddies). In recent decades, ou...

Research paper thumbnail of Strong southward transport events due to typhoons in the Taiwan Strait

Journal of Geophysical Research, 2009

1] Transport through the Taiwan Strait under the influence of five typhoons was investigated usin... more 1] Transport through the Taiwan Strait under the influence of five typhoons was investigated using both buoy observations and numerical model simulations during the period of 27 August to 5 October 2005. The results show that the effects of typhoons on the Taiwan Strait and its adjacent sea area caused strong southward transport events in the Taiwan Strait, which changed the direction of the Taiwan Strait northward transport temporarily. Typhoon-generated local wind stress and/or along-strait water level gradient were the direct driving factors in these southward transport events. The numerical results show that the Coriolis force made a negative contribution to these events and the contribution of the along-strait momentum gradient was insignificant.

Research paper thumbnail of Tide-surge Interaction Intensified by the Taiwan Strait

Journal of Geophysical Research, 2010

1] The Taiwan Strait is a long and wide shelf-channel where the hydrodynamics is extremely comple... more 1] The Taiwan Strait is a long and wide shelf-channel where the hydrodynamics is extremely complex, being characterized by strong tides, and where storm surges frequently occur during the typhoon season. Obvious oscillations due to tide-surge interaction were observed by tide gauges along the northern Fujian coast, the west bank of the Taiwan Strait, during Typhoon Dan (1999). Numerical experiments indicate that nonlinear bottom friction (described by the quadratic formula) is a major factor to predict these oscillations while the nonlinear advective terms and the shallow water effect have little contribution. It is found that the tide-surge interaction in the northern portion of the Taiwan Strait is intensified by the strait. Simulations based on simplified topographies with and without the island of Taiwan show that, in the presence of the island, the channel effect strengthens tidal currents and tends to align the major axes of tidal ellipses along the channel direction. Storm-induced currents are also strengthened by the channel. The pattern of strong tidal currents and storminduced currents along the channel direction enhances tide-surge interaction via the nonlinear bottom friction, resulting in the obvious oscillations along the northern Fujian coast.

Research paper thumbnail of Strong southward transport events due to typhoons in the Taiwan Strait

Journal of Geophysical Research, 2009

1] Transport through the Taiwan Strait under the influence of five typhoons was investigated usin... more 1] Transport through the Taiwan Strait under the influence of five typhoons was investigated using both buoy observations and numerical model simulations during the period of 27 August to 5 October 2005. The results show that the effects of typhoons on the Taiwan Strait and its adjacent sea area caused strong southward transport events in the Taiwan Strait, which changed the direction of the Taiwan Strait northward transport temporarily. Typhoon-generated local wind stress and/or along-strait water level gradient were the direct driving factors in these southward transport events. The numerical results show that the Coriolis force made a negative contribution to these events and the contribution of the along-strait momentum gradient was insignificant.

Research paper thumbnail of A two-way nested coupled tide-surge model for the Taiwan Strait

Continental Shelf Research, 2007

A two-way nested coupled tide-surge prediction model was established and applied in the Taiwan St... more A two-way nested coupled tide-surge prediction model was established and applied in the Taiwan Strait and adjacent sea area in this study. This two-dimensional (2D) model had a fine horizontal resolution and took into account the interaction between storm surges and astronomical tides, which made it suitable for depicting the complicated physical properties of storm surges in the Taiwan Strait. A two-way nesting technique and an open boundary condition developed from Flather's radiation condition and Røed and Smedstad's local mode idea, were successfully implemented in the model. A simulation experiment showed that the open boundary condition could be used in the coupled tide-surge model and that the performance of the two-way nested model was slightly superior in accuracy to that of the one-way nested one.