An Intercomparison of Tropospheric Ozone Derived From Two Aura Instruments
Open Access
- Author:
- Doughty, David C.
- Graduate Program:
- Meteorology
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- November 11, 2009
- Committee Members:
- Anne Mee Thompson, Thesis Advisor/Co-Advisor
Anne Mee Thompson, Thesis Advisor/Co-Advisor - Keywords:
- satellites
validation
verification
ozone
trace gas - Abstract:
- In situ ozonesonde measurements from the IONS-06 (NASA's INTEX [Intercontinental Chemical Transport Experiment] Ozonesonde Network Study) 2006 intensive Field campaign are compared with two estimates of ozone derived from Aura satellite retrievals taken daily in the same period (April-May 2006). The domain of validation is northwest North America, where gradients in column ozone can present technical challenges to precise ozone measurement. One estimate is based on mapping stratospheric ozone to forward trajectories for global coverage, then subtracting integrated stratospheric column ozone from the total column ozone to derive tropospheric column ozone. The other technique uses total column ozone and stratospheric pro files in an assimilation into a chemical-transport model that provides three-dimensional ozone fi elds. Although both retrieval techniques approximate variability observed in day-to-day in-situ measurements, it is found that the assimilation yielded tropospheric ozone column values 1.9% less than ozonesondes, and tropospheric ozone residual tropospheric ozone columns were 15.7% less than ozonesondes. Additionally, profi les from the assimilation method showed persistent high bias from 300 to 200 hPa, that partially canceled with negative biases in the lower troposphere, so apparent elevated accuracy of the assimilation method is to some degree a consequence of compensating errors within the troposphere. Finally, cases are examined to better understand potential factors that may be the performance of the assimilation, especially with regards to meteorological conditions. Analysis of cases suggest that some errors in the upper troposphere are due to complex synoptic conditions, but not all error can be explained by dynamics.