Title: The High Altitude Lidar Observatory (HALO): A multi-function lidar and technology testbed for airborne and space-based measurements of water vapor and methane
Presenting Author: Amin Nehrir
Organization: NASA Langley Research Center
Co-Author(s): Anthony Notari, David Harper, Fran Fitzpatrick,James Collins, Susan Kooi, Charles Antill, Richard Hare, Rory Barton-Grimley, John Hair, Richard Ferrare, Chris Hostetler

Abstract:
NASA Langley Research Center is developing the High Altitude Lidar Observatory (HALO) system to address the observational needs of NASA?s weather, climate, carbon cycle, and atmospheric composition focus areas. HALO is a multi-function airborne lidar being developed to measure atmospheric H2O and CH4 mixing ratios and aerosol/cloud/ocean optical properties using the DIfferential Absorption Lidar (DIAL) and High Spectral Resolution Lidar (HSRL) techniques, respectively. HALO is designed as an airborne simulator for future space-based greenhouse gas DIAL missions called out by the 2018 Earth Science Decadal Survey and serves as testbed for risk reduction of key technologies required to enable future space-based missions. To respond to a wide range of airborne process studies, HALO can be rapidly reconfigured to provide either CH4 DIAL+HSRL, H2O DIAL+HSRL, or CH4 DIAL+H2O DIAL measurements using three different high TRL lasers developed by Fibertek Inc. and a single multi-channel and multi-wavelength receiver. This paper will provide an overview of the HALO program including advancements of new laser technologies enabling for airborne and space-based measurements of water vapor and methane.