A number of LASP atmospheric scientists and students presented their work at the December AGU (American Geophysical Union) meeting in San Francisco. A sampling of the work includes:

Linnea Avallone presented a poster about a fastresponse ultraviolet absorption ozone instrument that her group has designed and deployed in both Antarctica and on the NASA WB-57F aircraft. They are able to make 10 Hz measurements of ozone with a precision of better than 5 ppb, which allows for the ozone flux studies presented by Lars Kalnajs (see below), and for sampling of fine scale structure in the atmosphere, such as that seen in dissipating rocket plumes.

Sean Davis (graduate student with Linnea Avallone) described measurements of ice water content in cirrus clouds during the 2004 Midlatitude Cirrus Experiment. The closed-path laser hygrometer used to measure total water has been demonstrated to be accurate to better than 20% (2-sigma). Recently begun comparisons of in situ measurements of ice water content with those derived from satellite remote sensors show that there is good agreement when the satellite is observing over the ocean or without significant cloud-cover below the cirrus.

Don Woodraska presented descriptions and analysis of the SEE atmospheric occultation measurements including comparisons to MSIS model predictions in a poster entitled “Solar occultation measurements of the thermosphere by the TIMED Solar EUV Experiment (SEE)”. Coauthors included Tom Woods and Frank Eparvier. Tom and Frank were also involved in the poster “Estimating the TIMED Satellite Drag Using the Solar EUV Experiment (SEE) Measurements", which presented analysis of the decay of the TIMED satellite orbit, making correlations with solar irradiance variability at different wavelengths in the EUV and FUV.

Lynn Harvey (working with Cora Randall) presented a poster on the correlation between anticyclone frequency and midlatitude ozone variability. Results show that ozone variability inside anticyclones is different than ozone outside anticyclonic air masses and that the differences between air mass types vary as a function of latitude, altitude, and season. Observed differences in the middle stratosphere are captured by NCAR’s coupled chemistry climate model, WACCM. An increase in anticyclone frequency in the middle stratosphere in WACCM is correlated with ozone decreases in this region, suggesting that dynamically forced ozone variability is contributing to ozone trends.

Odele Hofmann (graduate student with Peter Pilewskie) presented a paper “Cloud Properties Derived from Visible and Nearinfrared Reflectance in the Presence of Aerosols”. She presented results from the 2004 International Consortium for Atmospheric Research on Transport and Transformation Science (ICARTT) experiment showing how pollution outflow over the Gulf of Maine influences cloud properties derived from airborne and satellite remote sensing.

Lars Kalnajs (graduate student with Linnea Avallone) described recent work done in Antarctica looking at the flux of ozone to the snow-covered surface. Using three different methods, they showed that ozone is lost to the snow-covered surface, a finding that differs from published studies conducted in other locales. This loss to the surface is consistent with a proposed mechanism that involves halogen chemistry in or near the snow.

Cora Randall coauthored a presentation led by Bruno Nardi on the validation of HIRDLS ozone data showing that ozone profiles can be retrieved with high accuracy and vertical resolution, and precision better than 5%. She was also coauthor on a presentation showing that including line-of-sight variations significantly improves the accuracy of ozone retrievals applied to remote-sensing aircraft measurements.

Cynthia Singleton (graduate student with Cora Randall) presented inferred and modeled ozone loss calculations from the 2004- 2005 Arctic winter. The 2004-2005 Arctic winter can be characterized as one of the coldest Arctic winters ever recorded, which increased the potential for record ozone loss. They showed that a large amount of ozone loss was observed compared to other Arctic winters and that the chemistry transport model used was able to simulate the ozone loss for the dynamically active winter.