New Far-Infrared Measurements of Earth from NASA’s PREFIRE Mission

Despite representing more than half of Earth’s emission, the spectral nature of emission at wavelengths longer than 15 microns, termed the far infrared, has not been measured for more than four decades. Motivated by the important role far-infrared surface and atmospheric emission play in polar climates, NASA’s Polar Radiant Energy in the Far Infrared Experiment (PREFIRE) mission is filling this observing gap using two 6U CubeSats. Launched in late May and early June, respectively, each PREFIRE CubeSat carries a Thermal InfraRed Spectrometers (TIRS) that measures thermal emission at 64 wavelengths from 5 to 53 micrometers, effectively mapping 95 percent of the energetically relevant portion of Earth’s emission spectrum. This presentation will present the first far-infrared measurements of Earth since early experimental missions in the 1970’s and 80’s. When processed using innovative remote sensing techniques such as optimal estimation and machine learning, these near-complete emission spectra provide insights into spectral surface emissivity, water vapor, cloud properties, and the atmospheric greenhouse effect needed to advance models of thermal fluxes in the cold, dry conditions characteristic of the polar regions and upper atmosphere. Initial data from the first few months in orbit demonstrate how the PREFIRE measurements will help quantify the spectral signatures of the atmospheric and surface processes and feedbacks central to polar climate change.