Introduction to Remote Sensing
August 30th, 2007 at 9:58 pm (Education, Spacecraft, Technology)
Today was the first day of my Remote Sensing class, which I am attending remotely through USC’s Distance Education Network. In this 2.5-hour class, we covered an introduction to what remote sensing is, what kinds of instruments are used, and some highlights in terms of scientific discoveries that have been obtained through this technology. Here are some tidbits I took away that were surprises:
- Some of the earliest “remote sensing” involved sending cameras up with balloons, then retrieving them and developing their film. This kind of surveillance was used as far back as the Civil War!
- The (spectral) width of atmospheric absorption bands varies with atmospheric pressure, and therefore with altitude; as pressure increases, they spread out to cover adjacent wavelengths.
- Sea-surface height varies with water temperature (this is how they track El Nino) and with water depth (useful for mapping the ocean floor from orbital observations of the sea surface). Separating the two effects (lower sea-surface can mean colder water and/or an oceanic trough) would seem to be a significant challenge.
- Landsat-7, unlike its predecessors, can detect clouds in images on-board and decide to discard cloudy images.