PRECISE MONITORING OF TERRESTRIAL AEROSOLS AND TOTAL SOLAR IRRADIANCE: INTRODUCING THE NASA GLORY MISSION

The NASA Glory mission will support the U.S. Climate Change Science Program (USGCRP) by continuing and improving upon long-term monitoring of key forcings influencing global climate. Specifically, Glory is an Earth-orbiting observation and scientific data evaluation mission designed to achieve three critical objectives. One is to determine the global distribution, microphysical properties, and chemical composition of natural and anthropogenic aerosols and clouds with accuracy and coverage sufficient for a reliable quantification of the aerosol direct and indirect effects on climate. The second is to continue the 27-year total solar irradiance (TSI) measurement record to quantify the effect of solar variability on the Earth's climate. A third is to demonstrate the operational weather benefits of these measurements for eventual adoption by the National Polar-orbiting Environmental Satellite System (NPOESS) to meet three Aerosol and Cloud Climate Data Records (CDRs) incorporated into the NPOESS Integrated Operational Requirements Document (IORD-II) in 2001. These objectives are met by implementing two separate science instruments. The Aerosol Polarimetry Sensor (APS) has the ability to collect multi-angle photopolarimetric measurements of the troposphere along the satellite ground track within the visible, near- and short-wave infrared spectral regions from 400 to 2200 nm. Based on a proven technique demonstrated by the aircraft Research Scanning Polarimeter (RSP), APS is essential for NPOESS because it can provide aerosol measurements to an IORD minimum-required accuracy ten times better than possible with intensity radiometry offered by current sensors such as MODIS and MISR or the Visible Infrared Imager/Radiometer Suite (VIIRS) under development for NPOESS. The Total Irradiance Monitor (TIM) will measure sunlight incident on the Earth's atmosphere by collecting high accuracy and precision measurements of TSI. Glory is expected to be launched in December of 2008 and fly as part of the A-Train constellation of Earth-orbiting spacecraft, which will include the EOS Aqua and Aura, CALIPSO, CloudSat, OCO, and PARASOL satellites. APS data will be contemporaneous and synergistic with data from several other key A-Train instruments. Glory observations will improve retrievals of aerosol climate forcing parameters and global aerosol assessments with other A-Train instruments as well as paving the way for improved operational results from NPOESS. The scientific knowledge provided by the Glory mission will be essential to understanding climate change for sound, scientifically based economic and policy decisions related to environmental changes caused by climate variability as well as to offer significant improvements in operational weather observations and forecasting. It is expected that both Glory instruments will be subsequently flown on NPOESS platforms to continue their benefits to operational weather as well as climate trend assessments well beyond the initial Glory mission demonstration. The Glory TIM is a rebuild of the proven TIM currently flying on the Solar Radiation and Climate Experiment (SORCE), so will maintain continuity of the 27-year TSI record.