The Use of Far Infrared Spectral Measurements in Understanding Arctic Climate Change

Water vapor plays an important role in the process of Arctic amplification of global climate change. Diminishing sea ice and snow cover and increasing temperatures result in an increase in atmospheric moisture. As a strong greenhouse gas, the additional water vapor enhances atmospheric warming and impacts atmospheric processes such as evaporation and precipitation as well as cloud formation and maintenance. Water vapor is also a key factor in atmospheric radiative transfer. Far infrared (FIR) radiation (wavelengths greater than 15 µm) is particularly sensitive to changes in atmospheric moisture content and comprises more than half of the radiation emitted to space from the Arctic. Regular measurements of FIR radiation from space could give new insight to the role of water vapor in Arctic climate change. The Polar Radiant Energy in the Far InfraRed Experiment (PREFIRE) will make these measurements in order increase understanding of Arctic energy budget and the role of FIR radiation in Arctic climate. To that end, this study seeks to assess the utility of spectral FIR measurements in characterization of polar climate variability through improved atmospheric water vapor retrievals. Analysis of atmospheric retrievals simulated for the PREFIRE mission indicates improvement in both water vapor and temperature retrievals in the Arctic when far infrared radiation is measured in addition to mid infrared wavelengths (5 – 15 µm). These measurements, combined with the spatial and temporal resolution of the PREFIRE mission, will allow for new insights into the role of water vapor in the changing Arctic climate.