George Shevchenko and Alexander Romanov - PICES · and Alexander Romanov2 2Russian Institute of...
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WAVE STRUCTURE OF TIDAL MOTIONS NEAR THE NORTH KURIL ISLANDS AS REVEALED FROM SATELLITE ALTIMETRY MEASUREMENTS (ALTIMETRY OBSERVATIONS OF DIURNAL SHELF WAVES NEAR SAKHALIN AND THE NORTH KURIL ISLANDS) George Shevchenko 1 and Alexander Romanov 2 2 Russian Institute of Satellite Instruments, Moscow 1 Sakhalin Research Institute of Fisheries and Oceanography, Yuzhno-Sakhalinsk
Transcript of George Shevchenko and Alexander Romanov - PICES · and Alexander Romanov2 2Russian Institute of...
WAVE STRUCTURE OF TIDAL MOTIONS NEAR THE NORTH KURIL ISLANDS AS REVEALED FROM
SATELLITE ALTIMETRY MEASUREMENTS(ALTIMETRY OBSERVATIONS OF DIURNAL SHELF WAVES
NEAR SAKHALIN AND THE NORTH KURIL ISLANDS)
George Shevchenko1
and Alexander Romanov2
2Russian Institute of Satellite Instruments, Moscow
1Sakhalin Research Institute of Fisheries and Oceanography, Yuzhno-Sakhalinsk
Shelf waves at diurnal frequencies cause strong tidal currents, intensive energy dissipation and small-scale variations of diurnal amplitudes and phases.
The question: Can we use satellite altimetrydata to detect and examine diurnal shelf waves?
Areas where diurnal shelf waves are found:
Northeastern Sakhalin shelf [Rabinovich and Zhukov, 1984; Putov and Shevchenko, 1998; Ohshima et al., 2002; Shevchenko et al., 2004; Thomson et al., 2007]
Northern Hokkaido shelf [Odamaki, 1994]
Southern Kuril shelf [Efimov and Rabinovich, 1980; Kovalev and Rabinovich, 1980]
Central Kuril shelf (CTW) [Nakamura et al., 2000; Rabinovich and Thomson, 2001]
Northern Kuril shelf (present study)
Tidal energy flux for K1 wave [Kowalikand Polyakov, 1998]
Areas of strong tidal currents and significant tidal energy dissipation
Topex\Poseidon sub-satellite tracks where altimetry data (1993-2002) were used to determine tidal wave amplitudes and phases [Shevchenko, Romanov, 2004].
Obtained K1 and O1 amplitudes and phases were used
Spatial variations of K1 amplitude and phase of the north-directed velocity component on the northeastern Sakhalin based on current (30 moorings) and ice-drift (3 coastal radar stations) measurements [Shevchenko et al., 2004]
Strong diurnal currents in the narrow nearshorezone between Cape Elizabeth and Lunsky Bay
180º
Cape Elizabeth
Lunsky Bay
51.0
51.5
52.0
52.5
53.0
53.5
54.0
143.0 143.5 144.0
27
27
28
28
29
29
30
30
31
31
32
32
33
Computed K1 tidal ellipses [from Kowalik and Polyakov, 1998]
Spatial salinity distribution during ebb tides.
Predicted tidal currents. Shelf waves are responsible for the current divergence and convergence zones
143 144 145
50
51
52
53
54
21712172
21732174
21752176
22612262
22632264
22652266
23712372
23732374
23752376
51
127
203
Ascending TP tracks (51, 127 and 203) crossing northeastern shelf of Sakhalin Island.
Area of shelf waves
180º
51
K1 and O1 amplitude variability on the northeastern Sakhalin shelf
127
203
K1 amplitude, cm
15
20
25
30
35
1 2 3 4 5 6
O1 amplitude, cm
15
20
25
30
35
1 2 3 4 5 6
t.51
t.51
t.127
t.127
t.203
t.203
51
K1 and O1 phase variability on the northeastern Sakhalin shelf
127
203
K1 phase, deg
80
90
100
110
1 2 3 4 5 6
O1 phase, deg
40
50
60
70
1 2 3 4 5 6
t.51
t.51
t.127
t.127
t.203
t.203
80
90
100
110
K1 sea level amplitude and phase distribution on the base of coastal and mooring observations [Putov, Shevchenko, 1998]
Positive contribution of shelf wave
Negative contribution of shelf wave
≈ 25 deg
Amplitude, cm Phase, deg
Paramushir I.
Onekotan I.
Shiashkotan I.
Matua I.
Descending T/P tracks (160, 84, 8 and 186)
Assumed area of diurnal shelf waves
Shelf is too narrow and deep
First Kuril Strait Kamchatka
K1 amplitude, cm
22
27
32
1 2 3 4 5 6 7
O1 amplitude, cm
15
20
25
1 2 3 4 5 6 7
160
t.160
t.160
84
t.84
t.84
8
t.8
t.8
K1 and O1 amplitude variability on the North Kuril shelf
160
84
8
K1 phase, deg
170
180
190
200
1 2 3 4 5 6 7
O1 phase, deg
160
170
180
1 2 3 4 5 6 7
t.8
t.8
t.84
t.84
t.160
t.160
K1 and O1 phases variability on the North Kuril shelf
Phase, deg
-20
-10
0
10
20
30
1 26 51 76 101
126
151
176
201
226
251
Amplitude, cm
0
10
20
30
40
1 26 51 76 101
126
151
176
201
226
251
distance, km
K1 wave structure as combination of Kelvin and shelf waves
Shelf wave parameters:
Wavelength: 274 km Phase speed: 11.4 km/h Level amplitude: 10 cm Current speed: 31 cm/s
Kelvin wave parameters:
Wavelength: 21000 km Phase velocity: 880 km/h Level amplitude: 30 cmCurrent speed: 2 cm/sTrack 84
Track 8
First Kuril Strait Shiashkotan I.
Phase, deg
Amplitude, cm
Longshore distance, km
ConclusionsWe found increasing and decreasing K1 and O1 amplitudes along TP tracks 51 and 127 and significant phase shift between these tracks on the northeastern Sakhalin shelf.
Similar amplitudes and phases variations were found on the shelf of the North Kuril Islands (TP tracks 84 and 8). We consider these results as evidence of diurnal shelf waves in this area.
Estimations of diurnal shelf wave level and velocity amplitudes are not exact enough. We consider results obtained as a preliminary finding. To obtain more exact estimations, we need mooring current measurements in this area.
