Mirror emissivity measurements for the NASA AURA HIRDLS instrument

Conference item

The High Resolution Dynamics Limb Sounder (HIRDLS) instrument is scheduled for launch on the NASA AURA satellite in January 2004; it is a joint project between the UK and USA. HIRDLS is a mid-infrared limb emission sounder which will measure the concentrations of trace species and aerosol, and temperature and pressure variations in the Earth's atmosphere between about 8 and 100 km altitude on a finer spatial scale than been achieved before. HIRDLS has particularly stringent radiometric calibration accuracy requirements. A warm (280-300K) 'In-Flight Calibrator' (IFC) black cavity within the instrument plus a view to cold space are used to perform radiometric calibration. The cavity has an entrance aperture which is much smaller than the full beam size, and it is viewed through a focusing mirror. The cavity and focusing mirror are ideally maintained at the same temperature but differences of up to 1 C may exist, in which case a correction utilising the mirror emissivity can usefully be made. That emissivity has been measured at instrument level during pre-launch calibration by viewing an external target at the same temperature as the IFC while varying the calibration mirror temperature.

Authors: Barnett, J; Djotni, K; Hepplewhite, C; Oduleye, O; Palmer, C

• Publication status: Published
• Host title: INFRARED SPACEBORNE REMOTE SENSING XI
• Volume: 5152
• Pages: 238-246
• Publication date: 2003-01-01
• DOI: 10.1117/12.514591
• ISSN: 0277-786X
• ISBN: 0819450251
• Keywords: calibration; limb-viewing; reflectivity; infrared; HIRDLS