AMIGO
The Abundance of Methane by Interferometric Glint Observation (AMIGO) instrument employs three Fabry-Perot interferometers to measure atmospheric absorption spectra for several greenhouse gases in solar glints over oceans and from small bodies of water over landmasses. The need to understand the behavior of greenhouse gases as they contribute to climate change is critical for scientific understanding as well as in a regulatory capacity as international protocols are developed to help moderate the release of these gases into the atmosphere. Space borne measuring systems are needed because of the global nature of the problem; but, identification of release sites from space is difficult because each surface phenomenon contributes a small fraction to the total column abundance of greenhouse gases that is measured from space.
GLINT
A glint is a reflection of a light beam from a shiny surface such as the reflection of sunlight from a body of water on the Earth's surface. Nominally, the reflection of light from an air water interface is about 2% so while glint is very bright is not as bright as the sun. Because the sun subtends an angle of ~0.5 degrees when viewed from the Earth a glint from a smooth body of water fills a ~05 degree cone. This means that AMIGO when viewing the surface from space can potentially observe a glint from any body of water within a 0.5 degree wide area on the surface. For an altitude of 500 km and with a high sun this is a circle roughly 5 km in diameter. AMIGO uses a pointing system to keep the image of this area located properly on the focal planes for each of AMIGO's three channels throughout the passage of the spacecraft across the sunlit portion of its orbit.
AMIGO GASES
AMIGO measures atmospheric absorption over short spectral regions that contain features associated with methane, carbon dioxide and oxygen. The figure below shows these spectra which also contain some absorption caused by water vapor which AMIGO measures a well.
