GeoData Center Project: Nenana RiverRemote Sensing

Alaska is viewed from space by a number of different satellites. Depending on the time of year, the wavelength that the satellite senses earth surface data in, the amount of area that is sensed at a time and how these data are processed, the images of Alaska look very different.

Learn about remote sensing.

Landsat sensors record reflected and emitted energy from Earth in various wavelengths of the electromagnetic spectrum.

Landsats 5 and 7 "see" and record blue, green, and red light in the visible spectrum as well as near-infrared, mid-infrared, and thermal-infrared light that human eyes cannot perceive (although we can feel the thermal-infrared as heat).

Landsat data are acquired over the same area every 16 days.

This Landsat image (right) was acquired during the summer. It is a "real" color image.

Blue represents glaciers>
Greenrepresents leafy vegetation

Red-pink represents bare rock
Brown-reds represent shrubs
White represents clouds

MODIS (or Moderate Resolution Imaging Spectroradiometer) is a key instrument aboard two different satellites: Terra (EOS AM) and Aqua (EOS PM).

Terra's orbit around the Earth is timed so that it passes from north to south across the equator in the morning, while Aqua passes south to north over the equator in the afternoon. Terra MODIS and Aqua MODIS are viewing the entire Earth's surface every 1 to 2 days, acquiring data in 36 spectral bands, or groups of wavelengths (see MODIS Technical Specifications). These data will improve our understanding of global dynamics and processes occurring on the land, in the oceans, and in the lower atmosphere.

These images show the Nenana River Valley in summer (left) and winter (right).

The numbers mark the same spots on each image and are the same as those found on the topographic map.

What are some of the similarities and differences between the two images?
Which image would you use to map vegetation? water features?