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Prediction of tidal propagation and circulation in Chilean Inland Seas using a frequency domain model

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Title Prediction of tidal propagation and circulation in Chilean Inland Seas using a frequency domain model
Names Nunez, Rodrigo H. (creator)
Neshyba, Steve (advisor)
Date Issued 1990-08-03 (iso8601)
Note Graduation date: 1991
Abstract The calculated flow field and tide wave propagation in the Chilean Inland
Seas is modeled with a non-linear tidal embayment method (TEA-NL, Westerink
et al, 1988) and assimilation of tide records of the Chilean Hydrographic Institute.
Model is validated for two test cases with assimilated error-free boundary
conditions.
An Inverse Tidal Method (I. T. M.) developed as a time-domain method by
Bennett and McIntosh in 1982, is used to calculate the forcing functions, but in
the frequency-domain instead.
The model is first run using all available tide data. A second run with a
subset of five stations shows how the choice and location of stations affect the
prediction of tide wave propagation and flow fields. The boundary conditions
calculated by the I. T. M. for the cases of seven and five stations reproduced the
known data at the stations with like error magnitudes. However, for the seven
stations case, the tide wave propagation along the seaward side of Chiloe Island
(Pacific Ocean) propagated from South to North (the known direction of
propagation is from North to South). After disregarding two stations, the model
gave tide waves along the seaward side of Chloe Island propagating from North to
South. The model is clearly sensitive to perturbations introduced by hydraulics
factors other than pure tide wave propagation.
Charts of model simulation of flow fields are shown at 3, 6, 9 and 12 hours of
the M2 tidal cycle. Charts of phases and amplitudes are also shown.
Conclusions from the study are that the I. T. M. is a good data assimilation
technique to calculate the forcing functions of a numerical model, even when
known data is scarce. Further, the I. T. M. is a valuable aid in choosing locations
for new and useful data to improve the simulation.
Next steps required to improve the understanding of the Chilean Inland Seas
are a good field survey (based on the results of the I. T. M.), the development of a
transport model against which measured flow data can be compared, the inclusion
of river discharge in the boundary conditions, the preparation of trajectory charts
to demonstrate particle diffusion and advection, the expansion to three-dimensional
models, etc.
Genre Thesis/Dissertation
Topic Tides -- Chile -- Mathematical models
Identifier http://hdl.handle.net/1957/23532

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