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Question 3. How do ozone loss rates resulting from free radical catalytic processes evolve with time as a function of altitude, latitude, and solar zenith angle? How much ozone is destroyed by chemical processes within the vortex?

This question raises both (a) intravortex loss, which has been crudely quantified in a limited region within the antarctic vortex, as well as (b) more broadly distributed ozone erosion in the northern hemisphere well outside the arctic vortex. How will this situation evolve as chlorine loading approaches 5 ppbv?

• How do the concentration fields of the rate limiting radicals (ClO, BrO, NO2, OH, HO2) evolve with time as a function of altitude, latitude, and solar zenith angle poleward of 40°?

• Where do each of the rate limiting steps in the catalytic cycles peak as a function of altitude, latitude, region, and season?

• What is the evolution of the correlation of ozone versus the tracer fields (N2O, CH4, CFC-11), potential temperature, and potential vorticity between altitudes of 10 and 30 km poleward of 40°

• Does the degree of ozone loss regressed against the tracer fields (N2O, CH4, CFC-11), correspond to the ozone loss determined from dO3/dt surfaces using observed concentrations of the rate limiting radicals?

• How much air is "processed" within the vortex during its lifetime?

• At what rate and by what process does ClO return to "normal" levels of ClONO2 and HCl? What are the chemical and dynamical signatures of air as it spins out from the vortex following vortex break up?

• Why is enhanced ClO so smoothly distributed over large regions outside the vortex? Why is it "capped" at ~100 pptv?

• How will the picture change as the stratosphere approaches 5 ppbv of total chlorine?

III. Impact of Unmanned Aircraft  
 
Impact On Question 1: Obtaining decisive answers to the specific scientific questions raised in Question 1 cannot be obtained with current platforms: satellite, ground based, balloon, or manned aircraft. Effectiveness of previous studies has been seriously constrained by limitations on altitude, latitude, trajectory conditions (i.e. polar night), spatial resolution, and temporal coverage. This has prevented the quantification of vertical and horizontal advection, eddy mixing, and subsidence, as well as radiation heating and cooling rates, which constitute the foundation of efforts to quantify ozone loss.

The first order of business is to establish the time evolution of theta, PV, N2O, CH4, CFC-11, H2O, and O3 between 40° latitude and the pole, using aircraft-borne, in situ measurements between 10 and 30 km.

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