HR: 0830h
AN: A51A-09    [Abstracts]
TI: Instrument Drift Uncertainties and the Long-Term TOMS/SBUV Total Ozone Record
AU: * Stolarski, R S
EM: stolar@polska.gsfc.nasa.gov
AF: Atmospheric Chemistry and Dynamics Branch, NASA Goddard Space Flight Center Mail Code 613.3, Greenbelt, MD 20771 United States
AU: Frith, S
EM: smh@code916.gsfc.nasa.gov
AF: SSAI, Science Systems Applications Inc, Lanham, MD 20706 United States
AB: Long-term climate records from satellites are often constructed from the measurements of a sequence of instruments launched at different times. Each of these instruments is calibrated prior to launch. After launch they are subjected to potential offsets and slow drifts in calibration. We illustrate these issues in the construction of a merged total ozone record from 2 TOMS and 3 SBUV instruments. This record extends from late 1978 through the present. The question is "How good are these records?". We have examined the uncertainty in determining the relative calibration of two instruments during an overlap period in their measurements. When comparing a TOMS instrument, such as that on Nimbus 7, with an SBUV instrument, also on Nimbus 7, we find systematic differences and random differences. We have combined these findings with estimates of individual instrument drift into a monte-carlo uncertainty propagation model. We estimate an instrument drift uncertainty of a little larger than 1 percent per decade over the 25-year history of the TOMS/SBUV measurements. We make an independent estimate of the drift uncertainty in the ground-based network of total ozone measurements and find it to be of similar, but slightly smaller magnitude. The implications of these uncertainties for trend and recovery determination will be discussed.
DE: 0340 Middle atmosphere--composition and chemistry
DE: 0341 Middle atmosphere--constituent transport and chemistry (3334)
SC: Atmospheric Sciences [A]
MN: 2005 Joint Assembly