HALOE observations of the Arctic Vortex during the 1997 spring: Horizontal structure in the lower stratosphere

In late March, 1997, HALOE observed very low ozone (less than 1 ppmv at 48OK), low HCl, generally high NO x , and normal levels of H 2 O within the Arctic vortex. Trajectory mapping techniques show that the lower stratospheric Arctic vortex was locally chemically perturbed during this period. Regions of low HCl and low NO x mixing ratios found within the Arctic vortex indicate that partitioning within the odd chlorine family had been shifted from reservoir species to active species. Low O 3 mixing ratios within these regions strongly suggest that chlorine‐catalyzed photochemical destruction of O 3 had recently taken place. Regions of low HCl and higher NO x mixing ratios are also observed within the Arctic vortex. Correlations of O 3 , H 2 O, NO x and HCl with HF are used to quantify the changes in these constituents during March and early April, 1997. Temporal changes in the correlation of HCl and NO x with HF indicate increases in these species. No trend in the correlations of H 2 O or O 3 with HF was found in the lower stratosphere.