Three kind of application of ADCP is reported for long-term monitoring in coastal sea.(1)The routine monitoring of water qualities. The water quality and ADCP echo data (600 kHz) observed in the long-term are analgzed...Three kind of application of ADCP is reported for long-term monitoring in coastal sea.(1)The routine monitoring of water qualities. The water quality and ADCP echo data (600 kHz) observed in the long-term are analgzed at MT (Marine Tower) Station of Kansai International Airport in the Osaka Bay, Japan. The correlation between the turbidity and echo intensity in the surface layer is not good because air bubbles generated by breaking wave are not detected by the turbidity meter, but detected well by ADCP. When estimating the turbidity consists of plankton population from echo intensity, the effect of bubbles have to be eliminated. (2) Monitoring stirring up of bottom sediment. The special observation was carried out by using following two ADCP in the Osaka Bay, One ADCP was installed upward on the sea. The other ADCP was hanged downward at the gate type stand about 3 m above from the bottom. At the spring tide, high echo intensities indicating the stirring up of bottom sediment were observed. (3) The monitoring for the boundary condition of water mixing at an estuary. In summer season, the ADCP was set at the mouth of Tanabe Bay in Wakayama Prefecture, Japan. During the observation, water temperature near the bottom showed remarkable falls with interval of about 5-7 d. When the bottom temperature fell, the inflow current with low echo intensity water appears at the bottom layer in the ADCP record. It is concluded that when occasional weak northeast wind makes weak coastal upwelling at the mouth of the bay, the combination of upwelling with internal tidal flow causes remarkable water exchange and dispels the red tide.展开更多
Taiwan Island is at the joint of Eurasian Continent and Pacific Plate, under threatening of typhoons and northeasterly strong winds. Consequently, enormous human lives and properties are lost every year. It is necessa...Taiwan Island is at the joint of Eurasian Continent and Pacific Plate, under threatening of typhoons and northeasterly strong winds. Consequently, enormous human lives and properties are lost every year. It is necessary to develop a coastal sea-state monitoring system. This paper introduces the coastal sea-state monitoring system （CSMS） along Taiwan coast. The COMC （Coastal Ocean Monitoring Center in National Cheng Kung University） built the Taiwan coastal sea-state monitoring system, which is modern and self-sufficient, consisting of data buoy, pile station, tide station, coastal weather station, and radar monitoring station. To assure the data quality, Data Quality Check Procedure （DQCP） and Standard Operation Procedure （SOP） were developed by the COMC. In further data analysis and data implementation of the observation, this paper also introduces some new methods that make the data with much more promising uses. These methods include empirical mode decomposition （EMD） used for the analysis of storm surge water level, wavelet transform used for the analysis of wave characteristics from nearshore X-band radar images, and data assimilation technique applied in wave nowcast operation. The coastal sea-state monitoring system has a great potential in providing ocean information to serve the society.展开更多
Wave overtopping at a sea dike was observed using video images during a storm in July 2018 at Rizhao Coast,China.A shore-based video monitoring system was mounted to collect coastal images with a sample frequency of 1...Wave overtopping at a sea dike was observed using video images during a storm in July 2018 at Rizhao Coast,China.A shore-based video monitoring system was mounted to collect coastal images with a sample frequency of 1 Hz in the beginning 10 min of each hour during daylight.A method to extract the frequency,location,width and duration of individual overtopping events based on the shore-based video monitoring system was developed.A total of 6252 individual overtopping events were detected over a 360m long sea dike during the storm of 10 h in a safe and labor-saving way,enabling a detailed analysis of the temporal and spatial variation of wave overtopping.The temporal variation of overtopping duration,frequency and volume is basically in sync with the change of tidal level(R=0.87,0.82 and 0.76,respectively).The increase of wave height increases the overtopping frequency significantly.We found a high correlation between the hourly observed data and the predicted results of two commonly used formulae.Unlike the previous field measurements of overtopping that were limited in a single location,significant spatial variation of overtopping in the alongshore direction is found.The overtopping volume varies with a factor of 6 within the range of several wave lengths.It is further revealed that the spatial variation of overtopping is highly correlated with the alongshore variation of surf zone width with a correlation coefficient of 0.895.The present study suggests the feasibility of shore-based video monitoring technique to capture the main features of wave overtopping at coastal dikes,providing new possibilities to monitor wave overtopping in the field and to improve prediction tools.展开更多
文摘Three kind of application of ADCP is reported for long-term monitoring in coastal sea.(1)The routine monitoring of water qualities. The water quality and ADCP echo data (600 kHz) observed in the long-term are analgzed at MT (Marine Tower) Station of Kansai International Airport in the Osaka Bay, Japan. The correlation between the turbidity and echo intensity in the surface layer is not good because air bubbles generated by breaking wave are not detected by the turbidity meter, but detected well by ADCP. When estimating the turbidity consists of plankton population from echo intensity, the effect of bubbles have to be eliminated. (2) Monitoring stirring up of bottom sediment. The special observation was carried out by using following two ADCP in the Osaka Bay, One ADCP was installed upward on the sea. The other ADCP was hanged downward at the gate type stand about 3 m above from the bottom. At the spring tide, high echo intensities indicating the stirring up of bottom sediment were observed. (3) The monitoring for the boundary condition of water mixing at an estuary. In summer season, the ADCP was set at the mouth of Tanabe Bay in Wakayama Prefecture, Japan. During the observation, water temperature near the bottom showed remarkable falls with interval of about 5-7 d. When the bottom temperature fell, the inflow current with low echo intensity water appears at the bottom layer in the ADCP record. It is concluded that when occasional weak northeast wind makes weak coastal upwelling at the mouth of the bay, the combination of upwelling with internal tidal flow causes remarkable water exchange and dispels the red tide.
基金supported by National Natural Science Foundation of China (Grant No. 51109075)Fundamental Research Funds for the Central Universities (Grant No. 2011B05814)Doctoral Fund of Ministry of Education of China (Grant No. 20100094120008)
文摘Taiwan Island is at the joint of Eurasian Continent and Pacific Plate, under threatening of typhoons and northeasterly strong winds. Consequently, enormous human lives and properties are lost every year. It is necessary to develop a coastal sea-state monitoring system. This paper introduces the coastal sea-state monitoring system （CSMS） along Taiwan coast. The COMC （Coastal Ocean Monitoring Center in National Cheng Kung University） built the Taiwan coastal sea-state monitoring system, which is modern and self-sufficient, consisting of data buoy, pile station, tide station, coastal weather station, and radar monitoring station. To assure the data quality, Data Quality Check Procedure （DQCP） and Standard Operation Procedure （SOP） were developed by the COMC. In further data analysis and data implementation of the observation, this paper also introduces some new methods that make the data with much more promising uses. These methods include empirical mode decomposition （EMD） used for the analysis of storm surge water level, wavelet transform used for the analysis of wave characteristics from nearshore X-band radar images, and data assimilation technique applied in wave nowcast operation. The coastal sea-state monitoring system has a great potential in providing ocean information to serve the society.
基金This work was supported by the Fundamental Research Funds for the Central Universities(Grant Nos.B200202064,B200201064)the National Science Fund for Distinguished Young Scholars(Grant No.51425901)+2 种基金the Key Laboratory of Ministry of Education for Coastal Disaster and Protection,Hohai University(Grant No.202003)Projects supported by the Key Program of National Natural Science Foundation of China(Grant No.41930538)the National Natural Science Foundation of China(Grant No.51879096,51909076).
文摘Wave overtopping at a sea dike was observed using video images during a storm in July 2018 at Rizhao Coast,China.A shore-based video monitoring system was mounted to collect coastal images with a sample frequency of 1 Hz in the beginning 10 min of each hour during daylight.A method to extract the frequency,location,width and duration of individual overtopping events based on the shore-based video monitoring system was developed.A total of 6252 individual overtopping events were detected over a 360m long sea dike during the storm of 10 h in a safe and labor-saving way,enabling a detailed analysis of the temporal and spatial variation of wave overtopping.The temporal variation of overtopping duration,frequency and volume is basically in sync with the change of tidal level(R=0.87,0.82 and 0.76,respectively).The increase of wave height increases the overtopping frequency significantly.We found a high correlation between the hourly observed data and the predicted results of two commonly used formulae.Unlike the previous field measurements of overtopping that were limited in a single location,significant spatial variation of overtopping in the alongshore direction is found.The overtopping volume varies with a factor of 6 within the range of several wave lengths.It is further revealed that the spatial variation of overtopping is highly correlated with the alongshore variation of surf zone width with a correlation coefficient of 0.895.The present study suggests the feasibility of shore-based video monitoring technique to capture the main features of wave overtopping at coastal dikes,providing new possibilities to monitor wave overtopping in the field and to improve prediction tools.
