Tropospheric Ozone Laminar Structures and Vertical Correlation Lengths

1. Tropospheric Ozone Laminar Structures and Vertical Correlation Lengths Michael J. Newchurch1, Guanyu Huang1, Brad Pierce3, John Burris2 , Shi Kuang1, Wesley Cantrell1, Lihua Wang1, Patrick I. Buckley1 , Steve Johnson4, Kevin Knupp1, Dustin Phillips1 1University of Alabama in Huntsville, 2NASA/Goddard Space Flight Center, 3University of Wisconsin-Madison, 4NASA/Marshall Space Flight Center Introduction Ozone laminae frequently occur in ozonesonde and DIAL profiles. These ozone layers have significant potential implications for a variety of dynamic and chemical atmospheric processes and energy budgets (Newell et. al,. 2001). However, we have limited understanding of the mechanisms involving ozone layers and models rarely reproduce these laminae. (Colette et al., 2005a and 2005b,Stoller et al., 1999, Newell et al., 2001, Thouret et al., 2001).Based on two independent methods (Gradients and Wavelets), we study the morphology of ozone laminar structure and its applications to models and satellite retrievals. 10-year Huntsville ozonesonde data show a strong seasonal variation and the ubiquity of ozone laminae. DIAL profiles provide continuous observation of the sub-hourly evolution of atmospheric processes involving ozone laminae. 2. Motivation GEO-CAPE will measure tropospheric gases and aerosols at ~8km and hourly resolution. Vertical resolution is on the order of 5-10km in the troposphere. This vertical resolution is inadequate to resolve laminar structures that characterize tropospheric ozone and aerosols. Furthermore, GEO-CAPE information content in the PBL will likely be inadequate to resolve the processes responsible for air quality variability. We seek, therefore, to augment the space-borne measurements with a ground-based measurement system. Ozonesondes are extensively used in various atmospheric chemistry studies because of their low upfront cost and well-characterized behavior. However, the whole process for a sonde launch typically requires four hours. And four-hour ozonesonde resolution is prohibitively expensive. We therefore consider a lidar network to provide the necessary spatial and temporal resolution. 3. Ozone Laminae and Correlation Lengths 4. Nocturnal Jet Ozone Transport and STE Oct. 4 2008 Low frequency of layers near tropopause Co-located wind profiler Aerosol ext.coeff. at 291nm from O3 DIAL High frequency of layers below tropopause Co-located ceilometer backscatter Figure 1 Seasonal variations occur in altitudinal distributions. Layer height WRT to tropopause height. Figure 2 seasonal correlation of surface ozone w/ ozone aloft. Ozone in FT is not correlated with surface ozone Figure 6. Huntsville DIAL observes an ozone enhancement in the residual layer from the late evening to midnight on 4 Oct. 2008 due to the nocturnal jet ozone transport. Apr. 17 Apr. 23 Ozone DIAL retrieval Apr. 27 May 1 Dry Air Two clusters Sonde • Correlation Lengths • Definition: the altitude over which R^2 decreases from 1 to 0.5. • Each line is a regression through the correlations of at least 0.5. • Correlations >0.5 above the first occurrence of a statistically insignificant value (<0.5) are not considered. • Measurements of ozone above correlation length carries no info about surface ozone. • Corollary: To determine surface ozone concentration, a measurement must contain info from within the correlation length. Figure 7. A Stratosphere- troposphere exchange (STE) observed by Huntsville DIAL and Huntsville ozonesondes at April, 2010 5. RAQMS and Ozone DIAL Comparison May 4 May 5 May 6 May 1 May 2 May 3 May 4 May 5 May 6 May 7 May 8 May 3 May 7 Daytime PBL top collapsed EPA Surface Data Figure 8. The comparisons between RAQMS results with 1° by 1° horizontal resolution and ozone DIAL observations, May 4- 7 2010. • Ozone laminae occur frequently throughout the troposphere and exhibit seasonal and diurnal variability. • Correlation lengths suggest that surface ozone amounts are unrelated to contemporaneous ozone aloft. However, we expect upstream aloft ozone to affect surface amounts downstream. • Ozonesonde profiles, even as often as 4-hour intervals, are inadequate to resolve the spatio-temporal evolution of troposheric laminar structures. • NBL transport studies show promise for enhancing our knowledge of nighttime regional effects of pollution sources. • Regional CTMs struggle to reproduce the measured spatio-temporal evolution of ozone laminae. 6. Conclusion Figure 4. correlation between EPA surface ozone and ozone aloft based on Huntsville ozone DIAL profiles. EPA local measurement is located 4.5 miles southeast of Huntsville DIAL. Laminar structures cause anomalous behavior in correlation. Figure 5. Ozone observation of 4-hour temporal resolution (upper panel) vs. 10-min temporal resolution (DIAL data , lower panel) NOAA ESRL Global Monitoring Annual Meeting, May 17-18, 2011 Boulder CO. http://nsstc.uah.edu/atmchemmike@nsstc.uah.edu