Shipboard measurements of boundary layer NO, NO2, and NOy during the Pacific Transit (upper) and ACE-1 (lower) cruises. Vertical axes are mixing ratios in ppt (parts per trilli); arrows indicate approximate times where air from land (plumes) was sampled. Numbers indicate general air mass categories. During Transit, 1: polar/easterlies; 2: equatorial trades; 3: SW Pacific; 4: NZ/Australia. During ACE-1, 1: westerlies; 2: westerlies/Australia; 3: westerlies; 4: Australia.