AIRBORNE LIDAR MEASUREMENTS OF OZONE AND AEROSOL DISTRIBUTIONS OVER NORTH AMERICA AND THE WESTERN ATLANTIC OCEAN DURING THE INTEX-NA FIELD EXPERIMENT Edward V. Browell, (1) Johnathan W. Hair, (1) Carolyn F. Butler, (2) Marta A. Fenn, (2) Anthony Notari, (2) Susan A. Kooi, (2) Syed Ismail, (1) Melody A. Avery, (1) R. Bradley Pierce, (1) and Henry E. Fuelberg (3) (1) NASA Langley Research Center, Science Directorate, M.S.401-A, Hampton, VA 23692 USA. E-mail: e.v.browell@larc.nasa.gov, j.w.hair@larc.nasa.gov, s.ismail@larc.nasa.gov, m.a.avery@larc.nasa.gov, r.b.pierce@larc.nasa.gov (2) Science Applications International Corp., One Enterprise Parkway, Suite 300, Hampton, VA 23666. E-mail: c.f.butler@larc.nasa.gov, m.a.fenn@larc.nasa.gov, a.notari@larc.nasa.gov, s.a.kooi@larc.nasa.gov (3) Florida State University, Department of Meteorology, Tallahassee, FL 32306. E-mail: fuelberg@met.fsu.edu ABSTRACT The NASA Langley airborne Differential Absorption Lidar (DIAL) made extensive measurements of tropospheric ozone (O 3 ) and aerosol distributions during the Intercontinental Chemical Transport Experiment - North America (INTEX-NA) conducted from July 1 to August 14, 2004. The airborne DIAL system was operated simultaneously in nadir and zenith modes from the NASA DC-8 aircraft for complete atmospheric cross sections from near the surface to above the tropopause along the flight track. Large- scale distributions of O 3 and aerosols were obtained over North America (NA) and the western Atlantic Ocean on seventeen long-range flights of the DC-8. Air masses with enhanced O 3 and aerosols in the lower troposphere were observed in conjunction with the outflow of pollution from the United States (US) over the western Atlantic. Biomass burning plumes from distant Alaskan fires were frequently observed in the mid troposphere over NA as were air masses with mixtures of stratospheric air and polluted tropospheric air. The amount of O 3 from the stratosphere was found to be about 20% at low latitudes (<30 o N) and more than 40% at high latitudes (>40 o N). The first average latitudinal and longitudinal distributions of O 3 , aerosols, and potential vorticity (PV) were determined from the INTEX-NA data, and the relative occurrence of different air mass types was examined in different latitude and longitude regions. These results are discussed with respect to sources, sinks, and transport of air masses observed during this field experiment. 1. INTRODUCTION NASA Langley Research Center's airborne DIAL system participated in the INTEX-NA field experiment to investigate the large-scale variations of O 3 and aerosols associated with sources of pollution over NA and the transport of this pollution over the western Atlantic Ocean. The airborne DIAL system was operated on the DC-8 aircraft which was based in three locations for this field experiment: NASA Dryden Flight Research Center (DFRC), Edwards Air Force Base (AFB), California; Mid-America Airport, St. Louis, Missouri; and Pease Airport, Portsmouth, New Hampshire. Remote profile measurements of O 3 and aerosol backscatter and depolarization were made from near the surface to above the tropopause along the flight track of the DC-8. In situ measurements of O 3 , aerosols, and a wide range of trace gases were made onboard the DC-8 and correlated with the remote DIAL measurements. Meteorological analyses of PV distributions along the flight track were used to indicate the fraction of observed O 3 that could be attributed to stratosphere-troposphere exchange. Five- day backward trajectories were also used to indicate the possible origin of observed air masses. The airborne DIAL system used ultraviolet (UV) DIAL wavelengths of 288 and 300 nm for the measurement of O 3 profiles and multiple-wavelength aerosol backscatter profile measurements at 576/599 (nadir/zenith) and 1064 nm. Aerosol depolarization profiles were also made simultaneously below and above the aircraft at 576 and 599 nm, respectively. This airborne DIAL system and the techniques used for these measurements have been described in detail in many previous publications [see e.g., 1-3]. Seventeen long-range flights of the airborne DIAL system were accomplished during the INTEX-NA field experiment for a total of more than 130 hours of data. There were two data flights from Edwards AFB over the eastern Pacific Ocean to examine the types of air masses coming into the US from the west. There were two separate deployments to St. Louis with a total of five data flights, and there were ten data flights from Portsmouth. The locations of the various flight tracks