IN-SITU MEASUREMENTS OF BRO DURING AASE-II

BrO measured from the NASA ER-2 during AASE II exhibited a mean value (for 20-minute averages) of 5.4 +/- 0.3 pptv, with a standard deviatio n of 3.1 pptv. Ratios of BrO to available inorganic bromine (Br(y)) sh ow only slight increases in polar regions relative to midlatitudes. A comparison between observed latitudinal and diurnal variations of this same ratio and that calculated by photochemical models shows reasonab le agreement in behavior, but significant discrepancies in magnitude. It is unclear whether this difference is due to errors in measurements , models or both.