Abstract
Mixing ratio of nitric oxide (NO) and ozone were measured on board an aircraft over the western Pacific ocean between 7 and 10 th of March, 1989. The latitude range covered was from 35°N to 1°S. NO mixing ratio at 4.5 km varied between 10 and 45 pptv at latitudes between 32 and 15°N and the average NO mixing ratio was about 20 pptv. A peak in NO mixing ratio reaching 45 pptv was encountered near 20°N during both southbound and northbound flights. The average NO mixing ratio at latitudes between 10°N and the equator was about 10 pptv. The latitudinal variation in the ozone mixing ratio was basically similar to that of NO, suggesting larger sources of NO and ozone at mid-latitudes than at lower latitudes.
