If you look at something close to your face, you might notice its location seems to change depending on whether you have one or both eyes open. Perhaps the object seems to move left or right relative to the background, without even moving your head. This is what is known as parallax, the apparent difference in the location of an object based on point of view.

With satellite data, parallax is always something important to consider, because the features you see may not actually be where they appear to be. Parallax can cause meteorologists to misidentify the location of a storm cloud top or wildfire plume. In order to account for parallax, it’s necessary to understand the orbital characteristics of the two basic types of satellites for meteorological data — geostationary and polar — since that is what determines their viewing angle over Alaska. Once aware of how parallax affects satellite data, we can get to work correcting the displacement.

The following is a three-part series from 2022 by GINA’s satellite liaison Carl Dierking discussing parallax and its affect on satellite data in Alaska.