HR: 1400h
AN: SA53A-02    [Abstracts]
TI: The Long Term Trend and Solar Cycle Variation Observed in 12 Years of Hydroxyl Temperatures Over Davis, Antarctica.
AU: * French, J
EM: john.french@aad.gov.au
AF: Australian Antarctic Division, 203 Channel Hwy, Kingston, Tas 7050, Australia
AU: Burns, G
EM: gary.burns@aad.gov.au
AF: Australian Antarctic Division, 203 Channel Hwy, Kingston, Tas 7050, Australia
AB: Hydroxyl (6-2)-band rotational temperature observations have been accumulated at Davis station, Antarctica (68°S, 78°E) over 12 consecutive years since 1995. Hydroxyl emissions originate in a layer ~8km thick near 87km altitude and the rotational temperatures derived are a proxy for atmospheric temperature near the mesopause. This region is modelled to be sensitive to increases in CO₂and is expected to cool over the long term as the increased CO₂radiates more absorbed energy to space. Here we examine the seasonal and inter-year variability in hydroxyl temperatures and use a multiple linear regression analysis to extract solar cycle and long term linear trend coefficients. A total of 3413 nightly average temperatures are calculated from over 150,000 individual temperature measurements that pass selection criteria over the 12 year interval. Winter average temperatures, calculated from the nightly averages between day 108 to 258 each year vary between 203 and 210K and show a solar cycle dependence of about 0.05 K/solar flux unit (or 6K per solar cycle). The long term linear trend in these data (-0.11±0.12 K/year) is not statistically different from zero, in contrast to some published trends of up to -0.7 K/year. The winter of 2002 was anomalously warm before the unusual southern hemisphere strat-warm and early ozone hole break-up. Including this year has a considerable effect on the trend coefficients and our estimate of the number of years required to detect a statistically significant trend.
UR: http:www.aad.gov.au
DE: 0310 Airglow and aurora
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1630 Impacts of global change (1225)
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
SC: SPA-Aeronomy [SA]
MN: 2007 Joint Assembly