NO_y formed by precipitating electron events in 1991 and 1992: Descent into the stratosphere as observed by ISAMS

Abstract

NOAA 12 precipitating electron data has been examined together with ISAMS observations of nighttime NO 2 during electron events in November 1991 and May 1992. Energy deposition calculations suggest the significant formation of NO y during these events near 0.1 mbar and for 60°–80°latitude. ISAMS confirms increases of NO 2 from zonally averaged values of ≈1–5 ppbv prior to the events to values in excess of 30–40 ppbv with local maxima in excess of 140 ppbv. The increases occur within 2–3 days and are generally consistent with the calculated NO y formation rates due precipitating electrons. ISAMS data indicate the subsequent transport of the NO 2 into the stratosphere affecting NO 2 mixing ratios below 1 mbar and down to latitudes of ≈30°to 40°in both hemispheres.