marees terrestres bulletin d'informations - Université de la Polynésie ...
marees terrestres bulletin d'informations - Université de la Polynésie ...
marees terrestres bulletin d'informations - Université de la Polynésie ...
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Table 1: Adjusted tidal parameters of Hurghada station.<br />
Tidal<br />
Wave<br />
From<br />
cpd<br />
To<br />
cpd<br />
Amplitu<strong>de</strong><br />
Th. nm / s²<br />
Amplit.<br />
Factor<br />
Stand.<br />
<strong>de</strong>v. %<br />
Phase<br />
shift<br />
(<strong>de</strong>gree)<br />
Stand.<br />
<strong>de</strong>v.<br />
(<strong>de</strong>gree)<br />
Q1 0.501370 0.911390 48.4448 1.1354 0.351 -0.252 0.204<br />
O1 0.911391 0.947991 253.0250 1.1289 0.076 0.058 0.044<br />
M1 0.947992 0.981854 19.8995 1.1029 1.358 -0.931 0.787<br />
P1 0.981855 0.998631 117.7320 1.1321 0.213 0.154 0.122<br />
S1 0.998632 1.001369 2.7830 1.1706 12.551 20.35 6.964<br />
K1 1.001370 1.880264 355.8535 1.1121 0.064 -0.047 0.036<br />
N2 1.880265 1.914128 113.4428 1.1477 0.232 -0.010 0.136<br />
M2 1.914129 1.950419 592.5144 1.1489 0.049 0.005 0.029<br />
L2 1.950420 1.984282 16.7475 1.1624 1.702 0.142 0.961<br />
S2 1.984283 2.002885 275.6689 1.1384 0.100 0.024 0.058<br />
K2 2.002886 2.182843 74.9228 1.1222 0.004 0.164 0.058<br />
2MK3 2.451944 2.869714 2.8350 0.7927 0.035 -7.793 2.503<br />
M3 2.898264 2.903887 10.3383 1.1538 1.104 0.370 0.667<br />
MK3 2.927107 2.940325 0.5859 1.5732 0.142 -1.371 5.172<br />
S3 2.965989 3.001000 1.3475 1.0898 0.058 -0.294 3.065<br />
MN4 3.791510 3.833113 0.0601 2.8219 1.911 157.346 38.786<br />
M4 3.500000 4.499999 0.1671 2.1661 35.356 -151.520 22.490<br />
SN4 3.875000 3.901458 0.0144 10.5698 6.946 -164.754 37.656<br />
MK4 3.936000 6.00000 0.0292 69.1009 25.398 113.794 21.056<br />
7. Ocean Ti<strong>de</strong> Loading Computation<br />
Hurgada tidal station is of re<strong>la</strong>tively small distance to the shore line, so precise computation<br />
of the ocean ti<strong>de</strong> loading is nee<strong>de</strong>d. In or<strong>de</strong>r to compare the observed tidal parameters with the<br />
theoretical tidal signals, the ocean ti<strong>de</strong> loading contribution has to be subtracted from the<br />
observed tidal parameters. The computation of ocean ti<strong>de</strong> loading requires a mo<strong>de</strong>l of ocean<br />
ti<strong>de</strong>s (Zahran et al., 2006). Nowadays, there is a great progress on ocean ti<strong>de</strong> mo<strong>de</strong>ls, based on<br />
the data from TOPEX/POSEIDON. Ocean ti<strong>de</strong> loading has been predicted for the coordinates<br />
of Hurghada tidal station, using the FES2004 ocean ti<strong>de</strong> mo<strong>de</strong>l (Lyard et al., 2006) and the<br />
online computation with the program OLMPP, M. S. Bos and H. G. Scherneck. The<br />
resolution of the ocean tidal mo<strong>de</strong>l (FES2004) is 0.125°x0.125°. The computations were<br />
carried out applying the SPOTL-program (Agnew, 1996) at the coordinates of Hurghada tidal<br />
station. Table 2 shows the results of the ocean ti<strong>de</strong> loading vectors and the corrected tidal<br />
parameters for the main tidal waves.<br />
8. Discussion of Tidal Analysis Results<br />
The evaluation of the discrepancy between observed /corrected and the theoretical parameters<br />
was obtained by computing the residual vectors (Table 3) which are in the range from 0.39<br />
nm/s² for Q1 to 15.3 nm/s² for M2. The theoretical tidal parameters were estimated using the<br />
Dehant (1987) Earth mo<strong>de</strong>l (Eanes, 1994). A systematic bias is existing in the ratio between<br />
the theoretical amplitu<strong>de</strong> factors (Table 3) and the corrected ones (Table 2). This bias reaches<br />
1.5% when consi<strong>de</strong>ring the main diurnal and semi-diurnal tidal constituents. It is difficult to<br />
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