Professor, Department of Geophysics, Science and Research Branch, Islamic Azad University, Tehran, Iran
Professor, Department of Surveying and Geomatics Engineering, University of Tehran, Tehran, Iran
M.Sc. in Geophysics, Department of Geophysics (Gravimetry), Science and Research Branch, Islamic Azad University, Tehran, Iran
In recent years, several ocean tide models have been used to calculate tides using data of satellite and tide gauges data. Global ocean tide models have many applications in various sciences such as geophysics, geology and geodesy and oceanography. Considering the existence of many models, a quantitative evaluation of research, and ranking and selecting the best model of the global ocean tide Models is considered as an important objective
The purpose of this study is validation of global ocean tide models including, FES2004, FES99, NAO.99b, TPXO6.2, TPXO7.1, in the Persian Gulf and Oman sea and selecting the optimal model which can be used to determine the characteristics of the tide in these regions. Since most of the global tide models are designed for deep sea, so the models evaluated in this study have been chosen not only suitable to the latitude and the longitude of the Persian Gulf and Oman Sea but also to be used in the shallow sea as well Oman Sea.
In order to evaluate the models, the tidal analysis results obtaind from the models are compared with the tidal analysis based on tide gauge observations in the Persian Gulf and Oman Sea (Jask, Chahbahar,Shahid Rajaee,.Bushehr,Emam Hassan,Kangan).For the tidal analysis based on global ocean tide models we must test the models. To test the models TPXO6.2 and TPXO7.1, we have to use special software called Tide Model Driver (TMD). The TMD package contains scripted function for use in batch-mode Matlab processing. The input data are the geographical latitudes and longitudes of the studied area as well as the selected tidal components. The output data will be the amplitudes and the phases of the tidal components. The models (FES2004, FES99, and NAO99b) open in Matlab and need a short program in Matlab for determining the geographical situation in the area of the Persian Gulf and Oman Sea. The input data are the geographical latitudes and longitudes of the studied area as well as the selected tidal components. The output data will be the amplitudes and the phases of the tidal components.
In this research the tidal analysis based on tide gauges is conducted in two ways: tidal modeling and utilizing the results of IOS software. The tidal modeling was used with the Fourier sine and cosine series expansion and least squares.
In both ways it was resulted that the major section of elevation data at the stations related to main tidal components (K1, O1, M2, S2) and the largest amplitude observed in stations is related to M2. In this study the results of five models of the global tide ocean compared with the results acquired by tide gauges using software IOS and at all stations using several different statistical method .The statistical are.
- Amplitude root mean square
- Rss of amplitude root mean square
- Vector difference root mean squars
- Rss Vector difference root mean squars
Assesment of root mean square of amplitude of tidal components that are drived by the models in this research are compared with the tide gauges results (using both two manner, software and tidal modeling) showed that the root mean squares of all estimated amplitudes of models except FES99 is less than dm. The results of statisstical analysis showed that the best agreement with the tide gauge results with the tide results evaluated by models is corresponding to Jask and Chabahar which are closer the open sea; and results of the FES2004 model has the best agreement with the tide gauge results in the Persian Gulf and Oman Sea.
Results of FES2004 model which are compared with results of tidal gauge showed that this model has the lowest Rss for RMS for amplitude (8.5843cm). Results of FES2004 model which compared with results of IOS software showed that this model has the lowest Rss for RMS for amplitude (8.795 cm), also the FES2004 model has the lowest Rss for RMS differential vector (9.378 cm).