In this paper, some corrections was made to the assumption that the forcing is quasi-static, which is the basis of the nonlinear diabatic initialization scheme adopted by a global model T106L19. Thus the tidal signal ...In this paper, some corrections was made to the assumption that the forcing is quasi-static, which is the basis of the nonlinear diabatic initialization scheme adopted by a global model T106L19. Thus the tidal signal is expressed and excluded from the initialization scheme. It shows that the new scheme captures the semi-diurnal pressure variation and is much closer to the uninitialized field. Compared with the standard initialization scheme, both the anomaly correlation coefficients and RMS of 500 hPa geopotential height simulated under the new scheme have improved significantly.展开更多
Tidal motion is the source of short-term vertical motion that an ice shelf experiences, and hence has a significant impact on ice shelves. During the 2003/2004 Austral summer season, five days of GPS measurements were...Tidal motion is the source of short-term vertical motion that an ice shelf experiences, and hence has a significant impact on ice shelves. During the 2003/2004 Austral summer season, five days of GPS measurements were carried out on the front of the Amery Ice Shelf （AIS）, East Antarctica, by the 20th Chinese National Antarctica Research Expedition （CHINARE）. The GPS data was processed using GAMIT/GLOBK software with 2-hour static data segment and the vertical precision is less than 0.18 m. To verify our results for the vertical component, we compare the ice shelf GPS tidal signal with a tidal result derived from tide gauge measurements at China＇s Zhongshan Station on Antarctica. Comparison of the GPS results with the tide gauge were in good agreement in amplitude at the few cm level, which indicates that the tide under the front of Amery Ice Shelf is irregular semidiurnal tide, the maximal tidal differences is approximately 2 m. GPS data can be used to validate the ocean tide model around the Antarctic area and such studies are important to improve our knowledge of the Antarctic ice shelf mass balance and dynamical models of ice sheet/ocean interaction.展开更多
When using long range sound travel-time measurements to monitor the ocean temperature changes, the tidal effects must be corrected from the data. On the basis of a linear model of the tidal signal, and using measureme...When using long range sound travel-time measurements to monitor the ocean temperature changes, the tidal effects must be corrected from the data. On the basis of a linear model of the tidal signal, and using measurements taken within a specified period and at 4 hour intervals, a pseudorinverse method is used to predict the traveltime change due to the aggregate effect of barotropic tides along the sound path. The sampling period should be sufficiently long to give an acceptable prediction accuracy. In order to estimate all the major tidal constituents and separate closely spaced frequency components, a sampling period of 18 months is recommended. The linear model should include as many constituents as possible to minimize the predictioll error. This is feasible because in modeling the tide, the only parameter needed for each constituent is the frequency; and the freqencies of the astronomical components are known to a high precision, while the nonastronoIIilcal components are trivial in this application. Quantisation errors are reduced by means of multipath averaging.展开更多
基金Scientific research project for the 10th five-year economic development period(2001BA607B02) a project from the Chinese Academy of Meteorological Sciences (7046/2001-9Y-2)
文摘In this paper, some corrections was made to the assumption that the forcing is quasi-static, which is the basis of the nonlinear diabatic initialization scheme adopted by a global model T106L19. Thus the tidal signal is expressed and excluded from the initialization scheme. It shows that the new scheme captures the semi-diurnal pressure variation and is much closer to the uninitialized field. Compared with the standard initialization scheme, both the anomaly correlation coefficients and RMS of 500 hPa geopotential height simulated under the new scheme have improved significantly.
基金supported by the National Natural Science Foundation of China (40806076)State Key Laboratory of Cryospheric Science, Chinese Arcticand Antarctic Administration (20070206)Key Labora-tory of Polar Surveying and Mapping, State Bureau of Sur-veying and Mapping (200805)
文摘Tidal motion is the source of short-term vertical motion that an ice shelf experiences, and hence has a significant impact on ice shelves. During the 2003/2004 Austral summer season, five days of GPS measurements were carried out on the front of the Amery Ice Shelf （AIS）, East Antarctica, by the 20th Chinese National Antarctica Research Expedition （CHINARE）. The GPS data was processed using GAMIT/GLOBK software with 2-hour static data segment and the vertical precision is less than 0.18 m. To verify our results for the vertical component, we compare the ice shelf GPS tidal signal with a tidal result derived from tide gauge measurements at China＇s Zhongshan Station on Antarctica. Comparison of the GPS results with the tide gauge were in good agreement in amplitude at the few cm level, which indicates that the tide under the front of Amery Ice Shelf is irregular semidiurnal tide, the maximal tidal differences is approximately 2 m. GPS data can be used to validate the ocean tide model around the Antarctic area and such studies are important to improve our knowledge of the Antarctic ice shelf mass balance and dynamical models of ice sheet/ocean interaction.
文摘When using long range sound travel-time measurements to monitor the ocean temperature changes, the tidal effects must be corrected from the data. On the basis of a linear model of the tidal signal, and using measurements taken within a specified period and at 4 hour intervals, a pseudorinverse method is used to predict the traveltime change due to the aggregate effect of barotropic tides along the sound path. The sampling period should be sufficiently long to give an acceptable prediction accuracy. In order to estimate all the major tidal constituents and separate closely spaced frequency components, a sampling period of 18 months is recommended. The linear model should include as many constituents as possible to minimize the predictioll error. This is feasible because in modeling the tide, the only parameter needed for each constituent is the frequency; and the freqencies of the astronomical components are known to a high precision, while the nonastronoIIilcal components are trivial in this application. Quantisation errors are reduced by means of multipath averaging.
