Recent measurements of oxidized nitrogen compounds in the troposphere

Abstract

The role of active nitrogen in the photochemical production of ozone in the troposphere is thought to be well known. In rural and remote regions, a knowledge of the distribution of total odd nitrogen species (NOy) is critical to the analysis and development of global and regional atmospheric models. In the summer of 1986 a fairly comprehensive suite of measurements of NOx, NOy, HNO3, PAN, O3 and other species were made over the eastern Pacific in the middle free troposphere and boundary layer during the NASA GTE/CITE 2 program. More limited studies were made over the continental U.S. The measurements allow an examination of the partitioning of NOy into reservoir and active species and a comparison with results from earlier programs carried out in the fall of 1983 and spring of1984. More recently, the Mauna Loa Observatory Photochemistry Experiment (MLOPEX) was conducted in May and the first week of June 1988 at the NOAA GMCC station at 3.4 km altitude. Here measurements of NOx, NOy, HNO3, NO3−, O3, NMHCs, J(NO2), H2CO, HOOH, PAN, organic nitrates and other organic peroxides were measured around-the-clock. The experiment provided a large database from both upslope and downslope flow conditions. The results are contrasted with the aircraft flights and with multi-species measurement experiments organized by the NOAA Aeronomy Laboratory in the continental U.S. In particular, the ozone photochemical tendency, partitioning of NOx and NOy, and the role of measured organic nitrates are addressed.