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/).

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.

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

This tutorial will give a brief overview of Voyager.

Introduction to Voyager

Go to the Voyager viewer page: http://www.pacioos.hawaii.edu/voyager

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

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.

• Now select “monthly”.

• Click on “oldest”. This will automatically go to the earliest time step in the dataset.

You should now have a map for June 2002.

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.

• 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!)

• 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.

• 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.

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.

• 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: