`pathdistps` documentation

`pathdistps` is part of Antarctic Mapping Tools for Matlab (Greene et al., 2017). Click here for a complete list of functions in AMT.

The `pathdistps` returns the cumulative distance along a path in polar stereographic coordinates (true lat 71 S). Results are not exact because this is the distance in projected coordinates, which inherently have some distortion.

## Contents

## Syntax

d = pathdistps(lat,lon) d = pathdistps(x,y) d = pathdistps(...,'km') d = pathdistps(...,'ref',[reflat reflon]) d = pathdistps(...,'ref',[refx refy])

## Description

`d = pathdistps(lat,lon)` returns the cumulative distance `d` in meters along the path specified by geo coordinates `lat,lon`. Coordinates must be vectors of equal size.

`d = pathdistps(x,y)` returns the cumulative distance `d` in meters along the path specified by polar stereographic coordinates `x,y` where `x` and `y` are vectors of equal size in ps71 meters.

`d = pathdistps(...,'km')` simply divides output by 1000 to give distance in kilometers.

`d = pathdistps(...,'ref',[reflat reflon])` references the output to the track coordinate nearest to the location given by a two-element vector `[reflat reflon]`. This might be useful when analyzing distance along a satellite ground track relative to a point of interest such as a grounding line.

`d = pathdistps(...,'ref',[refx refy])` references the output as above, but using polar stereogprahic (ps71) coordinates.

## Examples

Use `reftrack` from the ICESat reference tracks toolbox and clip to the eastern hemisphere:

% Load reference track: [lat,lon] = reftrack(1304); % Clip to eastern hemisphere: lat = lat(lon>0); lon = lon(lon>0); % Plot for context: figure('position',[100 100 800 400]) subplot(1,2,1) bedmap2('gl','color','black','xy') plotps(lat,lon,'b-')

Calculate the total distance in meters and plot:

d = pathdistps(lat,lon); subplot(1,2,2) plot(d,lon) xlabel 'distance relative to the grounding line (m)' ylabel 'longitude (deg)'

Alternatively, calculate total distance in kilometers, referenced to (66.8575 S, 143.5678 E), which is a point near the ICESat track's intersection with the grounding line:

% Map a red star at the reference point: subplot(1,2,1) plotps(-66.8575,143.5678,'rp','markersize',12) % Calculate distance: d = pathdistps(lat,lon,'km','ref',[-66.8575 143.5678]); subplot(1,2,2) plot(d,lon) xlabel 'distance relative to the grounding line (km)' ylabel 'longitude (deg)'

## Citing AMT

If this function or any other part of Antarctic Mapping Tools is useful for you, please cite the paper that describes AMT.

Greene, C. A., Gwyther, D. E., & Blankenship, D. D. Antarctic Mapping Tools for Matlab. *Computers & Geosciences*. 104 (2017) pp.151-157. doi:10.1016/j.cageo.2016.08.003.

## Author Info

This function was written by Chad A. Greene of the University of Texas at Austin Institute for Geophysics (UTIG), April 2016.