AIRBORNE NITROUS-OXIDE OBSERVATIONS OVER THE WESTERN PACIFIC-OCEAN - SEPTEMBER OCTOBER 1991

The Langley tunable diode laser instrument package incorporated an add itional channel to measure nitrous oxide (N2O) during the Pacific Expl oratory Mission (PEM) West A. These measurements represent the first a irborne, fast response (5-s) N2O data set obtained within the troposph ere, Most data were recorded over the western Pacific between 0 degree s N and 45 degrees N latitude, 110 degrees E and 180 degrees E longitu de, and 0.3 to 12 km altitude. Important observations include a decrea sing N2O latitude gradient of approximately 0.4 parts per billion volu mn (ppbv) from northern midlatitudes to the equator, a decreasing N2O longitude gradient of 0.4 ppbv from the western Pacific to the central Pacific at northern midlatitudes, and an enhancement of 0.2 ppbv in t he boundary layer (altitudes below 0.5 km) relative to the rest of the tropospheric vertical profile. Other observations include increased N 2O mixing ratios within both urban and biogenic affected air masses an d reduced N2O mixing ratios in stratospheric intrusions. These relatio nships with air mass source characteristics are exhibited in the large -scale correlations between N2O and CO, CH4, and CO2 in the free tropo sphere. Atmospheric inputs of N2O are examined and the relative streng ths of continental biogenic and anthropogenic/industrial sources are e stimated. The data set is also examined for evidence of an oceanic sou rce of N2O.