Airborne measurements of total reactive odd nitrogen (NO_<i>y</i>)

Abstract

Airborne total reactive odd nitrogen measurements were made during August and September 1986 over the continental United States and off the west coast over the Pacific Ocean during NASAs Global Tropospheric Experiment/Chemical Instrumentation Test and Evaluation 2 program. The NO y instrument combined a catalytic surface converter which reduced NO y component species to NO on a heated Au surface with a NO/O 3 chemiluminescence detector. Measurements were made in the marine and continental boundary layer and the free troposphere up to 6.1 km altitude. NO y mixing ratios between 24 pptv and more than 1 ppbv were found, with median values of 101 pptv in the marine boundary layer, 298 pptv in the marine free troposphere, and 288 pptv in the continental free troposphere, respectively. The marine troposphere exhibited layered structure which was also seen in the simultaneously measured ozone mixing ratio and dew point temperature. The averaged vertical NO y profile over the ocean does not show a distinct gradient. The NO y mixing ratio over the continent decreases with increasing altitude. The latter is consistent with our understanding that the continents are the major source region for these gases.