Susan Smith has worked as an editor and writer in the technology industry for over 16 years. As an editor she has been responsible for the launch of a number of technology trade publications, both in print and online. Currently, Susan is the Editor of GISCafe and AECCafe, as well as those sites’ … More »
ArcticDEM Adds Largest Quantity of New Elevation Models
March 2nd, 2017 by Susan Smith
Peter Becker, ArcGIS product manager, Esri, talked with GISCafe Voice this week about the ArcticDEM project, that recently released the largest addition of new elevation models to the project. An ongoing collaboration effort between the National Geospatial-Intelligence Agency (NGA), the Polar Geospatial Center (PGC) and Esri, the ArcticDEM project produces high resolution elevation models to support the national security and scientific requirements of the Arctic. It also serves as a public data model that can be used by scientists to assess and augment climate change models. The NGA presented the new ArcticDEM elevation data the twentieth annual Esri Federal GIS (FedGIS) Conference, held February 13 and 14 at the Walter E. Washington Convention Center in Washington, DC.
Coupled with the accessibility of Esri’s online platform, ArcticDEM can meet the need for high-quality elevation data in remote locations and provide accurate measurement of topographic changes. In the latest release, more Arctic geography is covered than ever before, including more populated areas that have been in need of detailed location data to continue their analysis and navigation of the region. ArcticDEM data is a valuable source of data for maritime navigational charts that must have accurate and up-to-date coastal points of reference.
Becker said that optical imagery, collected for the ArcticDEM from DigitalGlobe WorldView satellites rather than radar, is vital for analysis. Nearly all types of analysis utilizes the topography and the shape of the land. “The topography is critical for all sorts of planning exercises, especially for determining where water is going to run off and also to monitor the things like rising or subsistence of the land,” Becker noted.
“Within areas like the Arctic there are a lot of issues related to the land and going lower because of thawing off the ground. Many issues can be monitored, then analyzed if one has an accurate terrain model of the area. That’s been lacking because things like SRTM didn’t exist above 60 degrees. This project is actually creating extremely high resolution terrain models, which not only create a basis for doing analysis, but because they are temporal, they allow us to monitor the terrain and see how things have changed.”
The PGC covers everything above 60 degrees latitude which includes all of Alaska and part of Russia. In this latest release, the ArcticDEM has covered a massive section of Canada and Greenland, and Esri has created a webmap that allows users to access this data. Stereographic projection is available of the North Pole, and for the area of Greenland there is no orthoimagery available.
“Now we have detailed DTMs of the area,” said Becker. “Slope maps were typically used for any type of mobility analysis to figure out how to get from one place to another. There are no roads there and the topography has a huge effect on navigation. Another useful area would be aspect maps, showing where the sun is shining at different times of the day.”
Temporal controls allow you to look at what the different DEMs look like at different points in time. You can see how the ice is changing in a given area from what it looked like a week before or a year before, etc. You will see variations in height, as some areas are increasing and some decreasing. “The app allows you to monitor any particular location and see how the terrain is actually changing.”
There are lot of decrease in ice in a lot of areas, and this type of analysis can be done anywhere in the Arctic. For all types of planning in the Arctic these datasets are critical because previously there was nothing available to measure these changes.
Environmentalists are looking to see how things change in incredible detail. “You’re looking at DTMs that have resolution of 2 meters. That’s a far better resolution that most of U.S. is mapped at,” said Becker. A similar project is underway by the PGS to map the Antarctic at a resolution of about 8 meters.
SRTM is a project that was undertaken in the year 2000 to map the world based on radar using a radar shuttle mission, to collect radar data of the world. That collected data was mapped at 30 meter resolution for the majority of the earth. Unfortunately it missed everything above 60 degrees latitude, so the whole of the North Pole was not mapped.
“What we’re getting are details in an area of the world that few people have managed to go to,” said Becker. “It is an area that is very dynamic and changing rapidly to various effects both natural and unnatural. We can actually start modeling and analyzing these datasets.
A lot of the snow actually moves, Becker noted. In some cases you can see the movement of the glacier over time. In one of the images, you could actually see the movement of the ice as it moved sideways. Sometimes it moves up and down.
The data is also used to fly drones as a DTM is needed to fly the area.
For climate change analysis, scientists can use the ArcticDEM to predict coastline recession, assess the effects of the ice on water resources, the movement of wildlife, etc.
Esri is putting the data up on the web in publicly available services that can be accessed by anybody so they can do their own analysis. “Those datasets can be used in app we provide, or ArcGIS desktop and website apps, or OGC Web Services, There’s actually an OGC Arctic Spatial data pilot project underway which shows interoperability between different data sets. This Arctic DEM is one of key datasets being used in this study.” Access to the data is also available at the NGA.
Esri does provide Landsat data of the Arctic so in this app you can go and turn on Landsat natural color imagery that will access the Landsat 8 archive that flies over the North Pole regularly. Landsat also has temporal imagery as services maintained by Esri, accessing the Landsat data stored in the Amazon Cloud.
The satellite flies over the Arctic region just about every day and over the equator every two weeks. Parts of the year the Arctic is dark so then there is obviously no coverage.
Clearly the ArcticDEM elevation models provide a valuable service in tracking the rate at which glaciers are receding, and a resource for monitoring, planning and adaptation. Communities can use the elevation models to monitor their own coastal erosion and prepare for high risk situations brought on by storms.
Explore visualized data from the ArcticDEM project at the ArcticDEM Explorer website.
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