> For the complete documentation index, see [llms.txt](https://coastwatch.gitbook.io/satellite-course/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://coastwatch.gitbook.io/satellite-course/archive/voyager-tutorial.md).

# Voyager tutorial

Voyager is an interactive map interface for visualizing and downloading oceanographic data that was developed by John Maurer from PacIOOS (<http://www.pacioos.hawaii.edu/voyager/>).&#x20;

OceanWatch (OW) partnered with PacIOOS to develop a separate instance of Voyager specifically for OceanWatch data (remote sensing data), as well as to add some new features.&#x20;

The PacIOOS version of Voyager contains a lot more data types (in situ, models, etc…), go check it out as well!&#x20;

This tutorial will give a brief overview of Voyager.&#x20;

## Introduction to Voyager

Go to the Voyager viewer page: [http://www.pacioos.hawaii.edu/voyager](http://www.pacioos.hawaii.edu/voyager/)&#x20;

On the Welcome screen, click on the “Help” tab and read through it to familiarize yourself with Voyager.

![](/files/-Lyp4aYUh-btxv3XL3qO)

Close the Welcome screen. In the left column, navigate to remote sending > satellite data.

## Choosing a dataset

In the side bar, under “satellite data”:

* select the “MODIS (chlorophyll)” dataset.
* Select the variable “chlorophyll”
* Select a time span (daily, weekly or monthly). \
  Observe the difference in missing data due to clouds between all time spans.&#x20;
* Now select “monthly”.&#x20;
* Click on “oldest”. \
  This will automatically go to the earliest time step in the dataset.&#x20;

You should now have a map for June 2002.

![](/files/-LypHqrf4zbbmP5L4rQY)

## Map options

Click on the + sign next to “map options”, to expand the map options menu.

* There, you can change the color scale used to display the data and adjust the minimum and maximum for the color bar.
* At the very bottom of the side bar, click on “lat/lon” to add a graticule to the map.
* Click on “range”, then click on a location on the map to display lines of equal distance from that location.&#x20;
* Click on “range” again to remove the lines from the map.
* Click on “distance”, then on 2 locations on the map to calculate the distance between them. \
  What is the distance between Japan and California? Click on “change units” to get the distance on km. (metric system for the win!)&#x20;
* Click on “distance” again to clear the map.
* Click on “area” to calculate the area of a polygon on the map. Then clear the map.

## Overlays

* Select a new dataset: "geo-polar blended (SST)". Display the monthly SST for September 2015 in ºC.
* Under the “Navigation” tab, click on the + sign next to “maritime boundaries”, then select "EEZ".
* Unselect EEZ, then at the very top of the side bar, click on “set region”. Select “Hawaii”. Then “set region”. Click on a location close to Kailua-Kona.&#x20;
* In the menu that pops up, click on “all” on the “show data plot” row. This generates a time-series of SST at that location.

![](/files/-LypIh2nhGKDXKEX318m)

## Sharing and saving maps

* Now, at the top right of the screen, click on “link”. Copy the link, and paste in a new browser tab. \
  You should get the exact same map, with the same options. This makes it very easy to share maps with others.&#x20;
* Zoom out until you can see the whole North Pacific. Then at the top right of the screen, click on “save image” then “get image”. This can take a while. Eventually, you will be prompted to save the image. It should look something like this:

![](/files/-LypJtPbC7eppbuV-nEp)