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Timestamp:
Sep 23, 2009, 4:31:28 PM (15 years ago)
Author:
ole
Message:

Another stab at the bathymetry section

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1 edited

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  • anuga_work/publications/boxing_day_validation_2008/data.tex

    r7522 r7529  
    7676
    7777\subsubsection{Bathymetry Data}\label{sec:bathymetry data}
    78 The bathymetry data used in this study was derived from the following
     78The bathymetry data used in this study were derived from the following
    7979sources:
    8080\begin{itemize}
     
    8888  coastline constrained using SRTM data (\url{http://srtm.csi.cgiar.org})
    8989  as well as Thai Navy charts no.\ 45 and no.\ 362; and 
    90 \item Thai Navy chart no.\ 358 providing water depths in Patong Bay.
     90\item Thai Navy chart no.\ 358 providing depth soundings inside Patong Bay.
    9191\end{itemize}
    9292
    93 These data sets were combined via gridding, interpolation and resampling to produce
    94 four nested grids which are relatively coarse in the deeper water and
    95 progressively finer as the distance to shore Patong Beach decreases as
    96 shown in Figure~\ref{fig:nested_grids}. This progression was chosen
    97 to match model resolution requirements according to the principle that
    98 shallow water flows are more sensitive to variations in elevation data
    99 than deep water flows. Consequently, the elevation data in shallow
    100 waters and on-shore need to be resolved better than elevation data
    101 further off-shore.
    102  
    103 The coarsest bathymetry was obtained by interpolating the DBDB2 grid
    104 to a 27~second arc grid. A subsection of this region was then replaced
    105 by nine second data which was generated by sub-sampling the three
    106 second of arc grid from NOAA. It is an artificially generated data set
    107 which is a subset of the original data.  A subset of the nine second
    108 grid was replaced by the three second data. Finally, a one arc second
    109 grid approximating the bathymetry in Patong Bay and the immediately
    110 adjacent regions was created by digitising Thai Navy bathymetry chart,
    111 no.\ 358. The digitised points and contour lines from this chart are
    112 shown in Figure~\ref{fig:patong_bathymetry}. The gridding was
    113 performed using \textsc{Intrepid}, a commercial geophysical processing
    114 package developed by Intrepid Geophysics\footnote{
    115 See
    116 \url{http://www.intrepid-geophysics.com/ig/manuals/english/gridding.pdf}
    117 for details on the Intrepid gridding scheme.}.
    118 Any points that deviated from the general trend near the boundary were
    119 deleted through a quality control process.
    120 The sub-sampling of larger grids was performed by using \textsc{resample},
    121 a Generic Mapping Tools (\textsc{GMT}) program \cite{wessel98}.
     93These data sets were used to produce four nested grids as
     94shown in Figure~\ref{fig:nested_grids}.
     95The nested approach was chosen to match model resolution requirements
     96according to the principle that shallow water flows are more sensitive
     97to variations in elevation data than deep water flows. Consequently,
     98the elevation data in shallow waters and on-shore need to be resolved
     99better than elevation data further off-shore.
     100The four nested grids were derived as follows:
     101\begin{itemize}
     102  \item \textbf{27~arc second grid} obtained by interpolating the two
     103    minute DBDB2 grid. This is the coarsest grid used in the
     104    simulations.
     105  \item \textbf{9~arc second grid} generated by sub-sampling
     106    the three second arc grid from NOAA.
     107  \item \textbf{3~arc second grid} formed as a subset of the three second grid
     108    from NOAA.
     109  \item \textbf{1~arc second grid} created by digitising Thai Navy
     110    bathymetry chart no.\ 358 followed by a gridding procedure as
     111    described below. This grid is the smallest and
     112    covers the Bay area and immediately adjacent regions.
     113    The digitised points and contour lines
     114    from this chart are shown in Figure~\ref{fig:patong_bathymetry}.
     115\end{itemize}
     116   
     117The gridding process for the finest grid was performed
     118using \textsc{Intrepid}, a commercial geophysical processing
     119package developed by Intrepid Geophysics\footnote{See
     120  \url{http://www.intrepid-geophysics.com/ig/manuals/english/gridding.pdf}
     121  for details on the Intrepid gridding scheme.}. Any points that
     122deviated from the general trend near the boundary were deleted
     123through a quality control process.  The sub-sampling of larger
     124grids was performed by using \textsc{resample}, a Generic Mapping
     125Tools (\textsc{GMT}) program \cite{wessel98}.
    122126
    123127
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