In order to obtain an accurate tide description in the China Seas, the 2-dimensional nonlinear numerical Princeton Ocean Model （POM） is employed to incorporate in situ tidal measurements both from tide gauges and TO...In order to obtain an accurate tide description in the China Seas, the 2-dimensional nonlinear numerical Princeton Ocean Model （POM） is employed to incorporate in situ tidal measurements both from tide gauges and TOPEX/POSEIDON （T/P） derived datasets by means of the variational adjoint approach in such a way that unknown internal model parameters, bottom topography, friction coefficients and open boundary conditions, for example, are adjusted during the process. The numerical model is used as a forward model. After the along-track T/P data are processed, two classical methods, i.e. harmonic and response analysis, are implemented to estimate the tide from such datasets with a domain covering the model area extending from 0° to 41°N in latitude and from 99°E to 142°E in longitude. And the results of these two methods are compared and interpreted. The numerical simulation is performed for 16 major constituents. In the data assimilation experiments, three types of unknown parameters （water depth, bottom friction and tidal open boundary conditions in the model equations） are chosen as control variables. Among the various types of data assimilation experiments, the calibration of water depth brings the most promising results. By comparing the results with selected tide gauge data, the average absolute errors are decreased from 7.9 cm to 6.8 cm for amplitude and from 13.0° to 9.0° for phase with respect to the semidiurnal tide M2 constituent, which is the largest tidal constituent in the model area. After the data assimilation experiment is performed, the comparison between model results and tide gauge observation for water levels shows that the RMS errors decrease by 9 cm for a total of 14 stations, mostly selected along the coast of China's Mainland, when a one-month period is considered, and the correlation coefficients improve for most tidal stations among these stations.展开更多
Eleven tidal constituents K_1, O_1, P_1, Q_1, M_2, S_2, N_2, K_2, M_4, MS_4 and M_6, which are extracted from 10 years TOPEX/Poseidon altimetry data along track points in the Bohai and Yellow Seas, are assimilated syn...Eleven tidal constituents K_1, O_1, P_1, Q_1, M_2, S_2, N_2, K_2, M_4, MS_4 and M_6, which are extracted from 10 years TOPEX/Poseidon altimetry data along track points in the Bohai and Yellow Seas, are assimilated synchronously into a two-dimension non-linear tidal model with adjoint method. And the bias between calculations and observations are provided. The deviations of M_2 are 7.1×10~ -2 m in amplitude and 4.7° in phase-lag. Those of O_1 are 2.8×10~ -2 m and 5.4° accordingly. Compared with other models, our discrepancy is less. It is shown that the precision of the model is more accurate. The co-tidal charts of the eleven constituents are also drawn. The general patterns are in good agreement with those literatures cited.展开更多
文摘In order to obtain an accurate tide description in the China Seas, the 2-dimensional nonlinear numerical Princeton Ocean Model （POM） is employed to incorporate in situ tidal measurements both from tide gauges and TOPEX/POSEIDON （T/P） derived datasets by means of the variational adjoint approach in such a way that unknown internal model parameters, bottom topography, friction coefficients and open boundary conditions, for example, are adjusted during the process. The numerical model is used as a forward model. After the along-track T/P data are processed, two classical methods, i.e. harmonic and response analysis, are implemented to estimate the tide from such datasets with a domain covering the model area extending from 0° to 41°N in latitude and from 99°E to 142°E in longitude. And the results of these two methods are compared and interpreted. The numerical simulation is performed for 16 major constituents. In the data assimilation experiments, three types of unknown parameters （water depth, bottom friction and tidal open boundary conditions in the model equations） are chosen as control variables. Among the various types of data assimilation experiments, the calibration of water depth brings the most promising results. By comparing the results with selected tide gauge data, the average absolute errors are decreased from 7.9 cm to 6.8 cm for amplitude and from 13.0° to 9.0° for phase with respect to the semidiurnal tide M2 constituent, which is the largest tidal constituent in the model area. After the data assimilation experiment is performed, the comparison between model results and tide gauge observation for water levels shows that the RMS errors decrease by 9 cm for a total of 14 stations, mostly selected along the coast of China's Mainland, when a one-month period is considered, and the correlation coefficients improve for most tidal stations among these stations.
文摘Eleven tidal constituents K_1, O_1, P_1, Q_1, M_2, S_2, N_2, K_2, M_4, MS_4 and M_6, which are extracted from 10 years TOPEX/Poseidon altimetry data along track points in the Bohai and Yellow Seas, are assimilated synchronously into a two-dimension non-linear tidal model with adjoint method. And the bias between calculations and observations are provided. The deviations of M_2 are 7.1×10~ -2 m in amplitude and 4.7° in phase-lag. Those of O_1 are 2.8×10~ -2 m and 5.4° accordingly. Compared with other models, our discrepancy is less. It is shown that the precision of the model is more accurate. The co-tidal charts of the eleven constituents are also drawn. The general patterns are in good agreement with those literatures cited.
