Abstract
We demonstrate for the first time that total ozone in the martian atmosphere is highly correlated with the dynamical tracer, potential vorticity, under certain conditions. The degree of correlation is investigated using a Mars global circulation model including a photochemical model. Potential vorticity is the quantity of choice to explore the dynamical nature of polar vortices because it contains information on winds and temperature in a single scalar variable. The correlation is found to display a distinct seasonal variation, with a strong positive correlation in both northern and southern winter at poleward latitudes in the northern and southern hemisphere respectively.The identified strong correlation implies variations in polar total ozone during winter are predominantly controlled by dynamical processes in these spatio-temporal regions. The weak correlation in northern and southern summer is due to the dominance of photochemical reactions resulting from extended exposure to sunlight. The total ozone/potential vorticity correlation is slightly weaker in southern winter due to topographical variations and the preference for ozone to accumulate in Hellas basin. In northern winter, total ozone can be used to track the polar vortex edge.The ozone/potential vorticity ratio is calculated for both northern and southern winter on Mars for the first time. Using the strong correlation in total ozone and potential vorticity in northern winter inside the polar vortex, it is shown that potential vorticity can be used as a proxy to deduce the distribution of total ozone where satellites cannot observe for the majority of northern winter. Where total ozone observations are available on the fringes of northern winter at poleward latitudes, the strong relationship of total ozone and potential vorticity implies that total ozone anomalies in the surf zone of the northern polar vortex can potentially be used to determine the origin of potential vorticity filaments.
Highlights
While the relationship of ozone and potential vorticity on Mars has never before been investigated, a strong correlation between potential vorticity, a dynamical tracer, and ozone provides several applications
If a strong correlation is apparent between potential vorticity and ozone at poleward latitudes in polar night, the spatial distribution of potential vorticity, which can be constrained by observations of temperature as a function of pressure (McConnochie, 2007) or through reanalysis datasets (Mitchell et al, 2015; Montabone et al, 2014), can be used as a proxy for ozone to extend the coverage of total ozone observational datasets
The strong relationship between total ozone and Potential vorticity (PV) on isentropic surfaces is demonstrated for Mars
Summary
While the relationship of ozone and potential vorticity on Mars has never before been investigated, a strong correlation between potential vorticity, a dynamical tracer, and ozone provides several applications. The annular nature was noted by Banfield et al (2004) and McConnochie (2007), with the latter using temperature retrievals from the Thermal Emission Spectrometer (TES) as a function of pressure to derive PV assuming zero winds at a fixed pressure level They found the northern winter polar vortex is better organised than the corresponding feature in the south and is likely to be a greater barrier to mixing. The lack of destruction mechanisms at this time of year potentially allows studies of the atmospheric dynamics by treating ozone as a quasi-passive tracer (Lefèvre et al, 2004) This indicates a significant correlation could exist between total ozone and PV on Mars due to the quasi-conservative nature of PV (Holton and Hakim, 2004). The ozone/PV ratio is calculated for Mars in Section 5 and used to investigate the creation of total ozone maps and identification of dynamical features in the surf zone
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