# btnav2

##

Last updated Sat Sep 18 21:04:35 1999

Comparison of NAV and BT velocities

## 1. SYNOPSIS

databtnav2(year_base, data_file, ps_file, plot_title, note )

## 2. DESCRIPTION

This Matlab function makes a plot of NAV anf BT velocities for comparions. The input ASCII file can be generated with the xtract(1) utility and must have the following columns:

1. Time in decimal days
2. Longitude in degrees
3. Latitude in degrees
4. U ship from ACCESS_VARIABLES
5. V ship from ACCESS_VARIABLES
6. Longitude from NAVIGATION
7. Latitude from NAVIGATION
8. Speed (in m/s) from NAVIGATION
9. Direction from NAVIGATION
10. U from BOTTOM_TRACK
11. V from BOTTOM_TRACK
12. Depth from BOTTOM_TRACK

The return value data is an array with the data from the input file, with the additionnal columns:

1. Ship speed
2. Ship direction
3. NAV eastward velocity
4. NAV northward velocity
5. BT speed
6. BT direction

## 3. PARAMETERS

year_base

  Base year corresponding to the times in the input file.

data_file

  Name of input data file.

ps_file

  Name for output postscript file.

plot_title

  Title for plot.

note

  Additionnal string to be printed on the plot.

## 4. RETURNS

This function returns an array with the data from the input data file an the addiionnal columns described above.

## 5. AUTHORS

Pierre Jaccard, Geophysical Institute, University of Bergen, 1999