OCEAN TIDES LOADING COMPUTATIONS

GRAVITY

Avalaible stations

Ocean Tides Models

SCW80           1°x1°                O1 - K1 - P1 - Q1 - K2 - M2 - N2 - S2 - MF

CSR3              0.5°x0.5°          O1 - K1 - P1 - Q1 - K2 - M2 - N2 - S2

FES95             0.5°x0.5°          O1 - K1 - P1 - Q1 - K2 - M2 - N2 - S2

ORI96             0.5°x0.5°          O1 - K1 - P1 - Q1 - K2 - M2 - N2 - S2

CSR4              0.5°x0.5°          O1 - K1 - P1 - Q1 - K2 - M2 - N2 - S2  

NAO99            0.5°x0.5°         O1 - K1 - P1 - Q1 - K2 - M2 - N2 - S2 - MF

GOT00            0.5°x0.5°          O1 - K1 - P1 - Q1 - K2 - M2 - N2 - S2

FES02             0.25°x0.25°      O1 - K1 - P1 - Q1 - K2 - M2 - N2 - S2

TPX06             0.25°x0.25°      O1 - K1 - P1 - Q1 - K2 - M2 - N2 - S2 - MF

FES04           0.125°x0.125°    O1 - K1 - P1 - Q1 - K2 - M2 -N2 - S2

This data base keeps ocean tides loading computations performed with the program CD104 developed at the International Center of Earth Tides. The tidal loading is evaluated according to a convolution of the ocean tide models with the Green’s functions derived by Farrell (Farrell, 1972) on the basis of the codes developed by Moens (Melchior et al.,1980). For the older models (CSR3, FES95, ORI96 and SCW80) we applied a mass conservation algorithm proportional to the tidal amplitude (Melchior et al.,1980).

We computed the tidal loading corrections using 10 different ocean tide models: CSR3.0 (Eanes, 1996) and CSR4.0, FES95.2 (Le Provost & al., 1994), FES02 (Lefèvre & al., 2002), FES04, GOT00 (Ray, 1999), NAO99 (Matsumoto & al., 2000), ORI96 (Matsumoto & al., 1995), SCW80 (Schwiderski, 1980). We replaced TPX02 (Egbert & al., 1994) by its new version TPX06. SCW80 model is used as a working standard since more than 20 years but its coverage is not sufficient in many areas. The new generation of ocean tide models really emerged about 1995 with the use of satellite altimetric data (Andersen & al., 1995). CSR3 and FES95.2 had been recommended by Shum & al.( 1997) and tested on tidal gravity data by Melchior & Francis (1996). CSR4.0, FES02, GOT00 are recent updates of previous well documented models. Most of the recent models have been intercompared and tested on tidal gravity data by Baker & Bos (2003) or Boy et al. (2003).

For each map, except FES04, it is possible to download the ocean tides model itself under a compressed form. Each record corresponds to a cell of the grid with the following format:

Sequence number, colatitude, longitude, area of the cell (m2), amplitude and phase of the ocean tides component Q1, O1, P1, K1, N2, M2, S2, K2, Mf.

For each wave in each map the tidal loading computation results are given for all the “available stations”, two lines for one station:

line1:

     STATION             LONG   LAT   ATTRACTION  LOADING            MAP   XY

Nr.       name                                       ampl.    phase    ampl.   phase

200 BRUXELLES       4.36     50.80  0.0912-159.83  0.0831 119.98  O1   SCW.  91

 

line 2:

     STATION             LONG   LAT   ALT.                  GLOBAL               MAP   XY

Nr.       name                                                                 ampl.  phase

200 BRUXELLES       4.36     50.80    101.              0.1334   162.31  O1   SCW.  92

 

In the first line we give separately the contribution due to gravitational attraction on one side and to flexure and potential change (LOADING) on the other. In the second line we give the global effect.

The amplitudes are given in microgal.

The phases a are local and are related to the Greenwich phases ao by the relation

a =  - (ao + d1l)

where l is the longitude (East positive) and d1 the first argument number of Doodson.

 

X :0  no mass conservation correction

     9 mas conservation correction proportional to the amplitude

Y:1 line1

    2 line 2

BIBLIOGRAPHY

 [1]         Baker, T.F., Bos, M.S. (2003): Validating Earth and ocean models using tidal gravity measurements. Geophys. J. Int., 152, 468-485.

[2]         Boy, J.-P., Llubes, M., Hinderer, J., & Florsch, N., 2003a. A comparison of tidal ocean loading models using superconducting gravimeter data, J. Geophys. Res., 108, B4, 2193, doi:10.1029/2002JB002050

[3]         Eanes, R., Bettadpur, S. (1996): The CSR3.0 global ocean tide model: Diurnal and Semi-diurnal ocean tides from TOPEX/POSEIDON altimetry, CRS-TM-96-05, Univ. of Texas, Centre for Space Research, Austin, Texas

[4]         Egbert, G., Bennett, A., Foreman, M. (1994): TOPEX/Poseidon tides estimated using a global inverse model. Journal of Geophysical Research, 99(C12), 24821-24852.

[5]         Farrell, W.E. (1972): Deformation of the Earth by surface load. Rev. Geophys., 10, 761-779

[6]         Lefèvre, F., Lyard, F.H., Le Provost, C., Schrama, E.J.O. (2002): FES99: a global tide finite element solution assimilating tide gauge and altimetric information. J. Atmos. Oceanic Technol., 19, 1345-1356.

[7]         Le Provost, C., Genco, M.L., Lyard, F., Vincent, P., Canceil, P. (1994): Spectroscopy of the ocean tides from a finite element hydrodynamic model. Journal of Geophysical Research, 99(C12), 24777-24797.

[8]         Matsumoto, K., Ooe, M., Sato, T., Segawa, J. (1995): Ocean tides model obtained from TOPEX/POSEIDON altimeter data. J. Geophys Res., 100, 25319-25330.

[9]         Matsumoto, K., Takanezawa, T., Ooe, M. (2000): Ocean tide models developed by assimilating TOPEX/POSEIDON altimeter data into hydrodynamical model: a global model and a regional model around Japan. J. Oceanography, 56, 567-581.

[10]      Melchior P., Moens M., Ducarme B. (1980): Computations of tidal gravity loading and attraction effects. Bull Obs. Marées Terrestres, Obs. Roy. Belg., 4, 5, 95-133.

[11]      Melchior, P., Francis, O. (1996): Comparison of recent ocean tide models using ground-based tidal gravity measurements. Marine Geodesy, 19, 291-330

[12]      Ray, R.D. (1999): A global ocean tide model from TOPEX/POSEIDON altimetry: GOT99. NASA Tech. Mem. 209478, Goddard Space Flight Centre, Greenbelt, MD, USA.

[13]      Schwiderski, E.W. (1980): Ocean Tides I, Global ocean tidal equations. Marine Geodesy, 3, 161-217

[14]      Shum, C.K., Woodworth P.L., Andersen, O.B., Egbert, G., Francis, O., King, C., Klosko, S., Le Provost, C., Li X., Molines, J.M., Parke, M., Ray, R., Schlax, M., Stammer D., Temey, C., Vincent P., Wunsch C. (1997): Accuracy assessment of recent ocean tide models. Journal of Geophysical Research, 102 (C11):25,173-25,194