Nitric oxide in the equatorial Pacific boundary layer: SAGA 3 measurements

Overall, NO mixing ratios for measurements made beween 0800 and 1600 LT averaged 2.9 ± 0.1 parts per trillion by volume (pptv), where the uncertainties represent 95% confidence limits in the mean. Concentrations were generally highest near the equator: NO mixing ratios obtained between 0800 and 1600 LT averaged 4.0 ± 0.2 pptv in the 5°S-5°N latitude band and 2.1 ± 0.2 pptv in the 5°-15° bands north and south of the equator. In the equatorial band the average diurnal behavior was a steady rise in NO from early morning until local noon, reaching a peak of about 4.5 pptv that remained until late afternoon before beginning a rapid decline. In the 5°-15° bands north and south of the equator the average diurnal curve for NO was flat (within experimental uncertainties) at about 2 pptv from 0800 to 1600. The NO and O₃ measured on SAGA 3 correspond to a loss rate of ozone of ~1 parts per billion by volume (ppbv) O₃/day in a region where mean surface O₃ is 10 ppbv. -from Authors