Abstract
Abstract. We examine whether the individual ozone (O3) measurements from the four Aura instruments can quantify the stratosphere-troposphere exchange (STE) flux of O3, an important term of the tropospheric O3 budget. The level 2 (L2) Aura swath data and the nearly coincident ozone sondes for the years 2005–2006 are compared with the 4-D, high-resolution (1° × 1° × 40-layer × 0.5 h) model simulation of atmospheric ozone for the same period from the University of California, Irvine chemistry transport model (CTM). The CTM becomes a transfer standard for comparing individual profiles from these five, not-quite-coincident measurements of atmospheric ozone. Even with obvious model discrepancies identified here, the CTM can readily quantify instrument-instrument biases in the tropical upper troposphere and mid-latitude lower stratosphere. In terms of STE processes, all four Aura datasets have some skill in identifying stratosphere-troposphere folds, and we find several cases where both model and measurements see evidence of high-O3 stratospheric air entering the troposphere. In many cases identified in the model, however, the individual Aura profile retrievals in the upper troposphere and lower stratosphere show too much noise, as expected from their low sensitivity and coarse vertical resolution at and below the tropopause. These model-measurement comparisons of individual profiles do provide some level of confidence in the model-derived STE O3 flux, but it will be difficult to integrate this flux from the satellite data alone.
Highlights
Quantifying and understanding the causes of changes in the tropospheric ozone (O3 ) burden are important topics for climate research and environmental studies, as ozone is a major greenhouse gas and plays a key role in the tropospheric chemistry
We evaluate if the Aura ozone measurements can provide useful information regarding processes, such as tropopause folds (TFs) (Danielsen, 1968), relate these events to stratosphere-troposphere exchange (STE) O3 fluxes; and examine the consistency amongst different Aura datasets, in the upper troposphere and lower stratosphere (UT/LS) region (300–100 hPa)
The Microwave Limb Sounder (MLS) swath (Fig. A7e) indicates an inversion structure at 52◦ N, 100 hPa, which does not appear in the simulation (Fig. A7f). These cases studies of the five Aura ozone measurements and the chemistry transport model (CTM) simulations, made on an instantaneous basis, confirm the model’s ability of reproducing the STE processes and show that the Aura measurements can detect some of the fine structures in O3, such as TFs and stratospheric intrusions deep into the troposphere, while they miss a large number of such cases, presumably due to instrumental noise, lack of sensitivity, and vertical resolution in individual measurements
Summary
Quantifying and understanding the causes of changes in the tropospheric ozone (O3 ) burden are important topics for climate research and environmental studies, as ozone is a major greenhouse gas and plays a key role in the tropospheric chemistry. The model and sonde have the same main shape (Fig. 3a): ozone decreases with height in the boundary layer (1000–800 hPa) and increases in the free troposphere with a clear inversion in the upper troposphere and another one of smaller magnitude at 125 hPa. The CTM misses the high values around 700 hPa. The CTM profile has larger variance in the free troposphere.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
