AIRCRAFT MEASUREMENTS MADE DURING THE SPRING MAXIMUM OF OZONE OVER HAWAII - PEROXIDES, CO, O-3, NOY, CONDENSATION NUCLEI, SELECTED HYDROCARBONS, HALOCARBONS, AND ALKYL NITRATES BETWEEN 0.5 AND 9 KM ALTITUDE

Between April 22 and May 11, 1992, ten flights of the University of Wy oming King Air were made during the maximum in tropospheric ozone over the central North Pacific Ocean in conjunction with the spring intens ive of the second Mauna Loa Observatory Photochemistry Experiment. Dur ing the first week of flights, an episode of remarkably large total re active nitrogen, NOy (similar to 2 ppbv) persisted in the 5-9 km altit ude region for 3-4 days. Backtrajectory calculation's combined with th e trace gas and aerosol measurements confirm that its source was due p rimarily to export from northern latitude continental surface regions. The total amount of odd nitrogen transported over Hawaii during this event was estimated to be 1-2% of the annual emissions from subsonic a ircraft or from stratospheric input. Throughout the measurement progra m layers of elevated O-3, NOy, condensation nuclei (CN), and other spe cies were frequently found between the onset of the marine boundary la yer temperature inversion and 4-5 km altitude. Structure and strong gr adients within these layers contribute to the daily variations seen at the 3.4 km elevation of the Mauna Loa Observatory during the nighttim e downslope flow. The dryness of these low-altitude layers and the cal culated air mass trajectories indicate that export from northern latit udes occurred mainly with subsidence to the Hawaii region rather than from transit just above the boundary layer inversion. There was no evi dence of recent stratospheric input to the altitude region sampled bel ow 9 km. However, the observations cannot distinguish whether O-3 inpu t from the stratosphere occurred earlier in the air mass histories at higher latitudes. Fine vertical scale anticorrelations between CN and O-3 or NOy were also often observed particularly in the last week of t he program when NOy mixing ratios were more typical of the remote trop osphere. These features are attributed to new particle formation near the tops of cloud convection episodes and they illustrate the importan ce of such processes in contributing to the detailed layering and dilu tion of some chemical species in the free troposphere during this time of year. Mean and median profiles for many of the title species are g iven for high and low-to-moderate NOy categories.