HR: 0830h
AN: A21D-0993    [PDF]
TI: The Good, the Bad, and the Ugly: 25 Years of TOMS Optical Degradation
AU: * Jaross, G
EM: jaross@qhearts.gsfc.nasa.gov
AF: SSAI, 10210 Greenbelt Rd., Suite 400, Greenbelt, MD 20706 United States
AU: Wellemeyer, C G
EM: cgw@qhearts.gsfc.nasa.gov
AF: SSAI, 10210 Greenbelt Rd., Suite 400, Greenbelt, MD 20706 United States
AU: Taylor, S L
EM: taylor@qhearts.gsfc.nasa.gov
AF: SSAI, 10210 Greenbelt Rd., Suite 400, Greenbelt, MD 20706 United States
AU: Cebula, R P
EM: richard_cebula@ssaihq.com
AF: SSAI, 10210 Greenbelt Rd., Suite 400, Greenbelt, MD 20706 United States
AU: McPeters, R D
EM: mcpeters@wrabbit.gsfc.nasa.gov
AF: Code 916, NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: Bhartia, P K
EM: bhartia@carioca.gsfc.nasa.gov
AF: Code 916, NASA Goddard Space Flight Center, Greenbelt, MD 20771 United States
AU: Krueger, A J
EM: akrueger@umbc.edu
AF: JCET\slash UMBC, 1000 Hilltop Circle, Baltimore, MD 21250 United States
AB: The long-term stability of the TOMS data products (total ozone, aerosols, reflectivity, and UVB) is determined primarily by the accuracy of time-dependent sensor calibrations. These calibrations include variations in components such as electronics and spectral registration. But none has had a greater influence on product uncertainty than optical degradation. Radiometry in the TOMS wavelength range, from 309 nm to 380 nm, is particularly susceptible to contaminants and their subsequent photo-polymerization. Each of the 4 TOMS instruments has exhibited a unique set of degradation characteristics, which resulted in distinctly different challenges to maintaining calibration. The Nimbus 7 TOMS (1978-1993) flight calibration system was inadequate for maintaining long-term calibration, so alternate methods were employed. The Meteor-3 spacecraft of the second TOMS (1991-1994) had a precessing orbit that introduced periods of large calibration uncertainty. And the scan mirror on the Earth Probe TOMS (1996-present) has degraded as much as 80%, resulting in complex, spatially and spectrally dependent changes. We present here a summary of TOMS degradation characteristics and their effect on calibration uncertainties. We expect the resulting uncertainty of the ozone trend, as measured by TOMS, to be in the 2%-3% percent range for the preceding 25 years.
DE: 0325 Evolution of the atmosphere
DE: 0394 Instruments and techniques
DE: 1694 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting