# adcp_tide

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Last updated Sat Sep 18 16:48:36 1999

Interpolate tide data to ADCP positions and time

## 1. USAGE

adcp_tide

## 2. DESCRIPTION

This Matlab script interpolates first all U and V tide components at ADCP positions for all times. These are then interpolated at ADCP ensemble times. The output file can be used to generate a vector plot of the tidal current at ADCP ensembles, and to detide ADCP currents.

Tidal data are read from five different input files:

1. Time in decimal days (suffix .t)
2. Longitude in degrees (suffix .lon)
3. Latitude in degrees (suffix .lat)
4. Eastward tidal component (suffix .u)
5. Northward tidal component (suffix .v)

ADCP ensemble times can be read from the output of the getnav utility. See below for the input .

## 3. PARAMETERS

The following parameters must be edited before running the script:

year_base

  Year base corresponding to input decimal days

tide_file

  Root name of ASCII files containing tide data. Extensions will be added automatically.

adcp_file

  Name of a file with ADCP time,longitude and latitude as output by utility getnav.

out_file

  Name of output file. See below for its .

## 4. INPUT FILE FORMAT

Input data have only one column with one data for each grid point. The grid defines a two dimensional geographical area with associated longitude, latitude, eastward and northward currents values at each point. These data must be listed in the same order in each file. If several times are listed in the time file, current values must repeat themselves in the corresponding files in the same order as well. All of these files can be generated with the xtract(1) utility.

## 5. OUTPUT FILE FORMAT

The generated file has the following columns:

1. ADCP time
2. Longitude
3. Latitude
4. Eastward tidal component
5. Northward tidal component

## 6. SEE ALSO

xtract(1)

## 7. AUTHORS

Pierre Jaccard, Geophysical Institute, University of Bergen, 1999