AIRBORNE LIDAR INVESTIGATIONS OF OZONE AND AEROSOLS DURING THE NASA TRACE-P FIELD EXPERIMENT

Edward V. Browell, PI; William B. Grant, Co-PI; Johnathan W. Hair, Co-I

Large-scale distributions of ozone (O3) and aerosols will be investigated in the western Pacific troposphere as part of the NASA TRACE-P mission to be conducted from March-April 2001.  During this investigation, we specifically propose to study the vertical and horizontal distributions of O3 and aerosol concentrations at high northern latitudes over the western Pacific in the spring.  An airborne differential absorption lidar (DIAL) system will be flown on the NASA DC-8 as part of a comprehensive airborne field experiment.  The airborne DIAL data will provide high-resolution cross sections of O3 (300 m in the vertical and 70 km in the horizontal) and aerosols (60 m in the vertical and 470 m in the horizontal) from the ocean surface to the tropopause along the DC-8 flight track. The two major objectives of this mission are to determine the chemical composition of the Asian outflow over the western Pacific in spring and the chemical evolution of this air.  By measuring the tropospheric cross section of O3 and aerosols from the DC-8 during TRACE-P, both of these objectives can be met.  In addition, by combining these data with in situ and, in some cases, remote measurements of temperature, trace gases, and water vapor, a better picture can be obtained regarding the composition and evolution as well as determining the types of air masses encountered.  Air mass types will be examined to estimate the relative impact of each air mass type on the tropospheric O3 budget over the western Pacific Ocean as a result of photochemical production/destruction and transport of O3.  Natural processes related to aerosol production and transport will also be investigated.

The remote lidar measurements of O3 and aerosol distributions will be correlated to several factors.  Those of primary concern are the atmospheric structure, the vertical transport of gases and aerosols between the marine mixed layer and the free troposphere, exchange between the troposphere and stratosphere, and the subsequent long-range advection of gases and aerosols in the free troposphere.  Aerosol optical properties will be derived from the multiple-wavelength lidar data and the depolarization ratios.    The O3 and aerosol data will also be used to provide information on the physical and chemical structure of the troposphere for each comprehensive set of in situ aircraft measurements.

During the first year of this 3-year research program, we will participate in the detailed planning for the TRACE-P field mission, prepare our UV DIAL system for the field, and make measurements of O3 and aerosols using the airborne DIAL system during March-April 2001.  Real-time (preliminary) data reduction of DIAL O3 and aerosol measurements will be provided in the field and posted on our web site after each flight.   We will also begin the data reduction process.  In the second year, the data reduction and interpretation of the DIAL data will be conducted as they pertain to the sources, sinks, and dynamics of O3 and aerosols over the western Pacific Ocean.  The integration of these data with the other in situ and remotely-sensed data during TRACE-P will also be completed and archived in the second year, which will lead to an improved understanding of O3 and aerosol budgets in the troposphere as well as being useful in making the air mass characterizations.  Also, atmospheric transport of gases and aerosols will be studied using the O3 and aerosol data.  In the third year, we will complete our collaborations with other science team members, prepare manuscripts related to the TRACE-P mission, and submit these joint papers for publication.