ternatively, 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 ot