# An Overview

The MEaSUREs Toolbox is a plugin for Antarctic Mapping Tools for Matlab.

## Contents

## Functions in this toolbox

This toolbox contains the the following functions:

`measures_data`is a low-level function for loading MEaSUREs surface velocity and grounding line data.

`measures_interp`interpolates surface velocities to any location(s). There are a few fancy interpolation options, including the ability to return zonal and meridional components of ice velocity, or the ability to return along-track and cross-track components of velocity relative to any arbitrary path.

`measures_displacement`estimates the location of ice parcel(s) after being advected for any amount of time. This is similar to the`flowline`function, but`flowline`helps you figure out*when*a parcel of ice will pass a point, whereas`measures_displacement`helps you figure out*where*the ice will be after a given amount of time.

`measuresps`plots ice speed as color, ice velocity as vectors (quiver plot), or grounding line as line or marker objects. The`measuresps`function does not require any special toolboxes.

`measures`is the original measures plotting function, but it relies on Matlab's Mapping Toolbox, which is expensive and not terribly useful. I'm trying to move away from dependence on the Mapping Toolbox, so expect dwindling support for this function in times to come.

`measuresann_interp`interpolates Mouginot et al.'s MEaSUREs Annual Antarctic Ice Velocity Maps 2005-2016, Version 1.

## Related functions

Here are some related functions that are not in the MEaSUREs toolbox, but are also freely available plugins for Antarctic Mapping Tools:

`flowline`is quite similar to the`measures_displacement`function described above, but calculates flowlines rather than discrete points.

- Antarctic Boundaries comes from the same research group as the MEaSUREs InSAR data, but provides a consistent, nonbreaking grounding line around the continent.

- MEaSUREs Annual Antarctic Ice Velocity Maps 2005-2016, Version 1. I have started on a Matlab implementation for this dataset, and by the time you read this, it will probably be on the Matlab File Exchange site.

- Other grounding lines. Check File Exchange for other grounding lines because there are many, measured by different methods, and each has a slightly different meaning. Current grounding lines are listed here.

## Installation

This toolbox does not require running any installation scripts, but you will need to download the surface velocity data and you'll need to make sure Matlab can find the data and these functions.

1. **Download the data:** Get the data from here: https://nsidc.org/data/NSIDC-0484. It's a file called antarctica_ice_velocity_450m_v2.nc.

2. **Add a path to the data and toolboxes:** Different distributions of Matlab have different ways of telling Matlab where to look for files. There's one way to do it that works on all versions of Matlab, but it requres a couple of steps: First, put all your AMT files into a directory, for me the filepath is `'/Users/chadgreene/Documents/MATLAB/AMT'` and in the `AMT` folder I have many subfolders with all the different AMT plugins. To tell Matlab that it should always look in the `AMT` folder for data and functions, create, go to your `MATLAB` directory and create a file called `startup.m`. It must be called `startup.m`, no other name will work, and it must be in the MATLAB folder. In the `startup.m` file write a line like this:

addpath(genpath('/Users/chadgreene/Documents/MATLAB/AMT'));

But of course you'll want to make sure you change the filepath to match your own file structure.

## Citing these datasets and functions

VELOCITY DATA: Rignot, E., J. Mouginot, and B. Scheuchl. 2017. MEaSUREs InSAR-Based Antarctica Ice Velocity Map, Version 2. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: http://dx.doi.org/10.5067/D7GK8F5J8M8R.

Mouginot, J., B. Scheuchl, and E. Rignot. 2017. MEaSUREs Annual Antarctic Ice Velocity Maps 2005-2016, Version 1. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. http://dx.doi.org/10.5067/9T4EPQXTJYW9.

Literature Citations: Mouginot, J., E. Rignot, B. Scheuchl, and R. Millan. 2017. Comprehensive Annual Ice Sheet Velocity Mapping Using Landsat-8, Sentinel-1, and RADARSAT-2 Data, Remote Sensing. 9. Art. #364. http://dx.doi.org/10.3390/rs9040364

Rignot, E., J. Mouginot, and B. Scheuchl. 2011. Ice Flow of the Antarctic Ice Sheet, Science, Vol. 333(6048): 1427-1430. doi:10.1126/science.1208336.

Mouginot, J., B. Scheuchl, and E. Rignot. 2012. Mapping of Ice Motion in Antarctica Using Synthetic- Aperture Radar Data, Remote Sensing. 4. 2753-2767. http://dx.doi.org/10.3390/rs4092753

GROUNDING LINE DATA: Rignot, E., J. Mouginot, and B. Scheuchl. 2011. MEaSUREs Antarctic Grounding Line from Differential Satellite Radar Interferometry. Boulder, Colorado USA: National Snow and Ice Data Center. http://dx.doi.org/10.5067/MEASURES/CRYOSPHERE/nsidc-0498.001.

A LITERARY REFERENCE FOR THE GROUNDING LINE DATA: Rignot, E., J. Mouginot, and B. Scheuchl. 2011. Antarctic Grounding Line Mapping from Differential Satellite Radar Interferometry. Geophyical Research Letters 38: L10504. doi:10.1029/2011GL047109.

ANTARCTIC MAPPING TOOLS: Greene, C.A., Gwyther, D.E. and Blankenship, D.D. Antarctic Mapping Tools for Matlab. Computers & Geosciences. doi:10.1016/j.cageo.2016.08.003.