A new tidal model for the Persian Gulf and Oman Sea based on satellite altimetry and coastal tidal gauge observations



Based on 11 years of TOPEX/Poseidon satellite altimetry and coastal tide gauge sea level observations, four tidal constituents, namely O1, K1, M2 and S2, are modeled for the Persian Gulf and Oman Sea using a time-wise approach according to the following details. By selecting the cycle 100 as the reference, 772 points on 12 paths along the track of the altimetry satellite footprints over the Persian Gulf and Oman Sea are selected as the center points of 772 circular cells that were used to catch the repeated MGDR data from cycle 8 through 345 that fall within the aforementioned circular cells with a radius of 0.053?. In this way 772 time series of the sea level observations located at the center of the circular cells are developed. These data were further corrected for all effects whose correction parameters are given by the MGDR data files; except the tidal correction that was kept to become the source of information for our tidal modeling. The gaps in the 772 satellite derived time series are filled via inverse solution of the autocorrelation function that was applied to the existing sea level variation data. Besides, the 1 hourly time series of sea level observations at 17 tide gauges along the Iranian coast line at the Persian Gulf and Oman Sea were used both to check the validity of the tidal models developed by the altimetry data at the 772 point over the above mentioned sea areas and to increase the accuracy of satellite derived tidal models at the shallow waters. The equally spaced 772 satellite altimetry derived time series and 17 time series at the coastal tide gauge stations are subjected to Fourier analysis to obtain the major tidal constituents, which are next used as the initial value within a least square solution to obtain the adjusted tidal frequencies, their phase angles and amplitudes. The result of this step for the satellite derived time series were modeling of all the existing tidal constituents with periods greater than 20 days, as the repetition of the TOPEX/Poseidon satellite altimetry observation is 9.915 days, except for the crossover points where the repetition time period is half. Next, via forward modeling, the effects of the modeled tidal constituents were removed from the original 772 time series to remain with the residual time series that were re-orders according to their observation hour, without considering their observation date in order to develop 2 hourly residual time series, which were used to derive the other short period tidal constituents.
The result of the numerical computation and the comparison of the satellite derive models with that obtained by tide gauge observations granted the success of the method and such a new tidal model for four tidal constituents namely, O1, K1, M2 and S2 is developed for the test area, i.e. Persian Gulf and Oman Sea.