GeoGratis in Action

GIS analyses of ice-sheet erosional impacts on the exposed shield of Baffin Island, eastern Canadian Arctic

Abstract: The erosional impacts of former ice sheets on the low-relief bedrock surfaces of Northern Hemisphere shields are not well understood. This paper assesses the variable impacts of glacial erosion on a portion of Baffin Island, eastern Canadian Arctic, between 68° and 72°N and 66° and 80°W. This tilted shield block was covered repeatedly by the Laurentide Ice Sheet during the late Cenozoic. The impact of ice-sheet erosion is examined with GIS analyses using two geomorphic parameters: lake density and terrain ruggedness. The resulting patterns generally conform to published data from other remote sensing studies, geological observations, cosmogenic exposure ages, and the distribution of the chemical index of alteration for tills. Lake density and terrain ruggedness are thereby demonstrated to be useful quantitative indicators of variable ice-sheet erosional impacts across Baffin Island.

GIS input data: Digital elevation model (DEM) data were obtained from GeoGratis. The Canadian Digital Elevation Data (CDED) dataset consists of an ordered array of ground elevations at regularly spaced intervals. The source data for CDED at the scale of 1:50 000 are extracted from hypsographic and hydrographic elements of the National Topographic Data Base (NTDB), various scaled positional data acquired from the provinces and territories, or remotely sensed imagery.

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The ice-sheet erosional impact on the Baffin Island Shield

The ice-sheet erosional impact on the Baffin Island Shield is indicated by a colour scale. The colour scale shows areas of weaker to stronger erosional impact, ranging from gray (weakest) to black (strongest) through purple and red.

The ice-sheet erosional impact on the Baffin Island Shield

The ice-sheet erosional impact on the Baffin Island Shield is indicated with an X for points where the impact is the most intense, with areas in red showing high impact and areas in green showing low impact. The ice drainage pathways are indicated with black arrows.

Using geomatics for stratospheric balloon flights

Inflating a stratospheric balloon

Figure 1: Inflating a stratospheric balloon

By Philippe Vincent, GIS Data Officer, Stratos Program, Canadian Space Agency

In partnership with the French space agency Centre National d'Études Spatiales, or CNES, the Canadian Space Agency (CSA) unveiled its new mid-latitude base for the launch of stratospheric balloons in June 2012, in Timmins, Ontario.

These remotely controlled balloons can carry up to 1.75 tons of equipment into the stratosphere. They require no engine or fuel, and are fully recoverable. The balloons can reach altitudes of up to 42 km.

The altitude at which they fly is too low to be covered by satellites (400 km and above), too high for aircraft (14 km and below) and passed through too quickly by sound rockets.

The balloons can be used to collect a wide range of important data on the Earth’s environment and atmosphere, or even to scan the universe for the purposes of astronomical research

Benefits

The CSA-CNES agreement allows Canada to provide its user community with frequent opportunities to access CNES stratospheric balloon flights every year, from here and elsewhere in the world. The balloons provide a new platform that is up to 40 times less costly than using a satellite or launcher. Canadian researchers and engineers are using the balloons to test technologies and thus contribute to advancing space science.

Using geospatial data

The use of geospatial data involves two components.

  1. Safety component

    This component is applied during the flight stage and consists of identifying zones or areas to be avoided during landing in order to prevent bodily harm (populated areas), damage to infrastructure (energy, transportation…) and to avoid protected areas (ecological zones).

  2. Recovery component

    This component begins during the flight stage and continues after the components have landed by parachute. This allows the recovery team to define ownership (public, private), the jurisdiction of the area, and the route to get to the landing sites.

Map supporting the safety component during the flight stage. The map contains data on infrastructure as well as a margin around populated areas. In yellow, an example of a trajectory and its landing zone.

Figure 2: Map supporting the safety component during the flight stage. The map contains data on infrastructure as well as a margin around populated areas. In yellow, an example of a trajectory and its landing zone.

 

Because they are dependent on winds, flights can last from 8 to 14 hours, and the balloons can travel several hundred kilometres. For this reason, the geospatial data covers the provinces of Ontario and Quebec in their entirety. Data sources include data from GeoGratis and GeoBase websites and more specifically from CanVec, NTDB collections and other external sources. The Canada Centre for Mapping and Earth Observation has been of invaluable help in establishing the database.

For more information, see the Stratos Program on the Canadian Space Agency website.