Long‐range transport of Asian outflow to the equatorial Pacific

The second Pacific Exploratory Mission to the Tropics (PEM T‐B) was conducted as part of NASA's Global Tropospheric Experiment (GTE) from 25 February through 19 April 1999. Long‐range pollution signatures are examined during four PEM T‐B flights that ranged as far northeast as California and as far southwest as coastal New Guinea. The signatures are studied to determine their ages and chemical evolution during transport. The chemical species examined include nonmethane hydrocarbons, halocarbons, and carbon monoxide. Wind data from the European Centre for Medium Range Weather Forecasts (ECMWF) are used to calculate backward trajectories along the four flight tracks. Results show that some pollutants originating from the Asian continent, and even farther west, are transported across the Pacific by the middle latitude westerly winds and reach the subtropical Pacific anticyclone where they subside and turn southwestward under the influence of the low level trade winds. The parcels ultimately reach the western Pacific near coastal New Guinea after 20–25 days of transit.