AGU Ocean Sciences Meeting (Feb. 2002) COAST abstracts:

• Ashe et al.
  
• Bane et al.
  
• Barth et al.
  
• Coletti et al.
  
• Haines et al.
  
• Karp-Boss et al.
  
• Kosro et al.
  
• Kurapov et al.
  
• Okeefe et al.
  
• Ott et al.
  
• Perlin et al.
  
• Ruttenberg et al.
  
• Sutor et al.
  

OS41E-75

M2 Internal Tide off Oregon: Inference From Data Assimilation

A. L. Kurapov, G. D. Egbert, J. S. Allen, R. N. Miller,
S. Y. Erofeeva, and P. M. Kosro

A linearized, baroclinic, spectral in time, inverse model has been
developed and applied to study the M2 internal tide during May-July
1998 in a limited area (40x60 km) near the Oregon coast, where
measurements of surface currents are available from two coast-based
HF radars. The surface current data are harmonicly analyzed in short
time segments and the resulting harmonic constants are assimilated
into the model with use of the generalized inverse method.
ADCP mooring currents are analyzed in a similar way and are used
for validation of data assimilation results. Data analysis reveals
substantial intermittency of the internal tide, both in amplitude
and phase. Representers obtained as a part of the generalized inverse
solution show the zone of influence of surface data. In particular,
since the M2 frequency is superinertial, the information from the
surface data propagates along baroclinic beams throughout the water
column. Most baroclinic signal in the area is generated outside our
small domain and baroclinic fluxes at the OB are restored by means
of data assimilation. Experiments with synthetic data demonstrate
that the choice of error covariance for the OB fluxes affects
wave radiation through the OB, and hence model performance. An OB
condition covariance that allows radiation is obtained by nesting.
Assimilation of surface velocity radial components measured by the
HF radars captures the temporal variability of the internal tide
both near the surface and at depth, and improves the rms difference
between the solution and the ADCP measurements, thus demonstrating
that surface velocity observations contain valuable information
about the internal tide.