7.4 Simultaneous water vapor and ozone lidar observations of a stratospheric intrusion during the MOHAVE-2009 campaign

Wednesday, 26 January 2011: 2:45 PM
3B (Washington State Convention Center)
Thierry Leblanc, California Institute of Technology, Wrightwood, CA; and I. S. McDermid and A. Hauchecorne

Ozone and water vapor signatures of a stratospheric intrusion were simultaneously observed by the Jet Propulsion Laboratory lidars located at Table Mountain Facility, California (TMF, 34.4N, 117.7W) during the Measurements of Humidity in the Atmosphere and Validation Experiments (MOHAVE) 2009 campaign. Here, these observations are placed in the context of the meridional displacement of the tropopause by Rossby waves, and the resulting contrast in the properties of the air masses sampled by lidar. The intrusion event is characterized using the ozone and water vapor lidar measurements, the potential vorticity (PV) fields advected by the high-resolution transport model MIMOSA, and 10-days isentropic back-trajectories. In the early days of the MOHAVE campaign (Oct 16-19, 2009), the lidars systematically sampled subtropical air from the ground to the cold point tropopause (i.e., ~400 K, ~17 km). The advected PV maps indicated that the subtropical jet was, in average, located north of TMF during that time. On October 19, an upper Low located in the vicinity of TMF caused the subtropical jet stream to reinforce while approaching the site from the west. By October 20 the jet stream was located just south of TMF, wrapping counterclockwise around the upper Low, and the lidars sampled air masses with midlatitudes and polar lowermost stratospheric characteristics between 310 K (~7 km) and 380 K (~14 km). The ozone and water vapor simultaneously measured by the TMF lidars throughout the campaign were found to be largely anti-correlated, which is consistent with the typical upper troposphere-lower stratosphere duality characterized by a wet and ozone-poor subtropical upper troposphere and a dry and ozone-rich extra-tropical lowermost stratosphere. However, it is shown that this ozone and water vapor anti-correlation relation collapsed just after the stratospheric intrusion event, pointing out to mixed air along the jet stream before and/or during its displacement south of TMF. The various highly-correlated signatures observed during this event demonstrate the strong capability of the water vapor and ozone lidars at TMF, and provide new confidence in the future detection by lidar of long-term variability of water vapor and ozone in the UTLS
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