[1] The NASA Transport and Chemical Evolution over the Pacific (TRACE-P) aircraft mission was conducted in February-April 2001 over the NW Pacific (1) to characterize the Asian chemical outflow and relate it quantitatively to its sources and (2) to determine its chemical evolution. It used two aircraft, a DC-8 and a P-3B, operating out of Hong Kong and Yokota Air Force Base (near Tokyo), with secondary sites in Hawaii, Wake Island, Guam, Okinawa, and Midway. The aircraft carried instrumentation for measurements of long-lived greenhouse gases, ozone and its precursors, aerosols and their precursors, related species, and chemical tracers. Five chemical transport models (CTMs) were used for chemical forecasting. Customized bottom-up emission inventories for East Asia were generated prior to the mission to support chemical forecasting and to serve as a priori for evaluation with the aircraft data. Validation flights were conducted for the Measurements Of Pollution In The Troposphere (MOPITT) satellite instrument and revealed little bias (6 ± 2%) in the MOPITT measurements of CO columns. A major event of transpacific Asian pollution was characterized through combined analysis of TRACE-P and MOPITT data. The TRACE-P observations showed that cold fronts sweeping across East Asia and the associated warm conveyor belts (WCBs) are the dominant pathway for Asian outflow to the Pacific in spring. The WCBs lift both anthropogenic and biomass burning (SE Asia) effluents to the free troposphere, resulting in complex chemical signatures. The TRACE-P data are in general consistent with a priori emission inventories, lending confidence in our ability to quantify Asian emissions from socioeconomic data and emission factors. However, the residential combustion source in rural China was found to be much larger than the a priori, and there were also unexplained chemical enhancements (HCN, CH 3 Cl, OCS, alkylnitrates) in Chinese urban plumes. The Asian source of CCl 4 was found to be much higher than government estimates. Measurements of HCN and CH 3 CN indicated a dominant biomass burning source and ocean sink for both gases. Large fractions of sulfate and nitrate were found to be present in dust aerosols. Photochemical activity in the Asian outflow was strongly reduced by aerosol attenuation of UV radiation, with major implications for the concentrations of HO x radicals. New particle formation, apparently from ternary nucleation involving NH 3 , was observed in Chinese urban plumes.

Mixing ratios of tropospheric carbon monoxide measured by a gas filter radiometer carried aboard the space shuttle during November 1981 are reported. The data represent average mixing ratios in the middle and upper troposphere between 38°N and 38°S latitude. Approximately 10,000 individual measurements were obtained in each of the two channels of the instrument. The data are presented in the form of plots that show the individual carbon monoxide mixing ratio measurements as a function of latitude and longitude and in the form of maps that show the data averaged over 5° latitude by 5° longitude squares. The data show relatively little variation in the mixing ratio in the southern hemisphere; however, the data from both the tropics and the northern hemisphere show strong gradients with both latitude and longitude.

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The Measurement of Air Pollution from Satellite (MAPS) experiment measured the distribution of middle tropospheric carbon monoxide (CO) from the space shuttle during October 1984. The data represent average mixing ratios in the middle troposphere between 57°N and 57°S. Approximately 75,000 individual CO measurements were obtained during the 9‐day mission. The data are presented in maps that show the CO mixing ratios averaged over 5° latitude by 5° longitude areas for 6 days of the mission. Comparisons with concurrent, direct measurements taken aboard aircraft show that the inferred concentrations are systematically low by 20–40% depending upon which direct measurement calibration standard is used. The data show that there are very large CO sources resulting from biomass burning over South America and southern Africa. Measured mixing ratios were high over northeast Asia and were highly variable over Europe.