In situ measurements of stratospheric ozone depletion rates in the Arctic winter 1991/1992: A Lagrangian approach

Abstract

Abstract. A Lagrangian approach has been used to assess the degree of chemically induced ozone loss in the Arctic lower stratosphere in winter 1991/1992. Trajectory calculations are used to identify air parcels probed by two ozonesondes at different points along the trajectories. A statistical analysis of the measured differences in ozone mixing ratio and the time the air parcel spent in sunlight between the measurements provides the chemical ozone loss. Initial results were first described by von der Gathen et al. [1995]. Here we present a more detailed description of the technique and a more comprehensive discussion of the results. Ozone loss rates of up to 10 ppbv per sunlit hour (or 54 ppbv per day) were found inside the polar vortex on the 475 K potential temperature surface (about 19.5 km in altitude) at the end of January. The period of rapid ozone loss coincides and slightly lags a period when temperatures were cold enough for type I polar stratospheric clouds to form. It is shown that the ozone loss occurs exclusively during the sunlit portions of the trajectories. The time evolution and vertical distribution of the ozone loss rates are discussed.

Results of an interactively coupled atmospheric chemistry – general circulation model: Comparison with observations

“…The high interannual standard deviation of 0.6 ppbv stresses the strong influence of the dynamic variability on chlorine activation. This result is in agreement with the SLIMCAT simulations and analyses of observations (Müller et al, 1996(Müller et al, , 1997aRex et al, 1998Rex et al, , 1999von der Gathen et al, 1995), which also indicate a strong interannual variability in ClO x mixing ratios and related ozone changes during the northern winters 1991/92 to 1996/97. In the northern hemisphere, activated chlorine is first converted to ClONO 2 during February and March, and recovers back to HCl only later, in good agreement with observations.…”

Trajectory hunting: A case study of rapid chlorine activation in December 1992 as seen by UARS

“…Thus the MLS data for December 24 are shown at 472 K, 530 K, and 598 K, while the data for December 29 are shown at 465 K, 520 K, and 585 K. However, for simplicity, we refer to the three levels as "465 K", "520 K", and "585 K" throughout the paper. Large changes in potential vorticity along a trajectory are indicative of substantial influence from diabatic effects or small-scale diffusion [e.g., Rex et al, 1998]. To guard against these situations, we checked In addition, these particular parcels follow paths that are confined well inside the vortex.…”

“…The difference between the initial and final concentrations of ozone (or any other species) for these parcels can then be at- 0148-0227/00/1999JD901054509.00 "Trajectory hunting" is a technique to find air parcels that have been sampled at least twice over a period of several days. The trajectory hunting approach that we employ in this paper is similar to the Match technique [e.g., Rex et al, 1998]. However, there are clear differences.…”

ILAS observations of chemical ozone loss in the Arctic vortex during early spring 1997

“…Quantitative analyses of the amounts of ozone destruction and/or ozone loss rates in the polar vortex have been done using TOMS data, satellite-borne ozone profiling sensor data such as MLS, and ozone sonde data at particular ground stations [Newman et Rex et al [1997Rex et al [ , 1998Rex et al [ , 1999 applied a new technique called "Match" to a data set of ozone sonde measurements. They calculated the amount of ozone change in an air parcel that has passed two separate locations inside the polar vortex so that dynamic effects can be neglected and only chemical changes remain.…”