HR: 12:05h
AN: A42A-08    [Abstracts]
TI: Quasi-Lagrangian Chemical Sampling during INTEX-B
AU: Latto, A
EM: latto@met.fsu.edu
AF: Florida State University, Department of Meteorology, Tallahassee, FL 32306-4520, United States
AU: * Fuelberg, H
EM: fuelberg@met.fsu.edu
AF: Florida State University, Department of Meteorology, Tallahassee, FL 32306-4520, United States
AB: Lagrangian sampling requires taking in situ measurements of an air parcel, followed by later sampling of that same parcel after it has moved to a new location. This sampling is virtually impossible to achieve for atmospheric parcels; however, a quasi-Lagrangian approach is more feasible. Quasi-Lagrangian sampling involves taking measurements of a parcel at one location, and later sampling of what is believed to be the same, or a very similar parcel, at a different location. A goal of the Intercontinental Chemical Transport Experiment—Phase B (INTEX-B) was to perform quasi-Lagrangian sampling of pollution plumes traveling from Asia toward the United States. Initial chemical measurements during INTEX-B were taken by NASA's DC-8 flying laboratory during flights out of Anchorage, AK. The subsequent, downwind measurements were taken by NCAR's C-130 aircraft during flights out of Seattle, WA. We determined quasi-Lagrangian sampling by creating back trajectories at 1 min intervals along all the C-130 flight tracks. As each trajectory moved back in time, it was continually checked against navigation data of the DC-8 flight being considered. If the trajectory came within 1 deg lat/long, 50 mb, and 1 hour of any location along the DC-8's flight track, quasi-Lagrangian sampling was assumed. Although these thresholds seem reasonable based on trajectory uncertainty, they are subject to revision. The periods between quasi-Lagrangian sampling ranged from one to four days, with the parcels traveling in the lower, middle, and upper troposphere. Usually there were several quasi-Lagrangian sampling periods during each pair of flights. The paper will list the INTEX-B flight legs during which quasi-Lagrangian chemical sampling was achieved, describe the origins and paths taken by the sampled air, and describe the meteorological evolutions that occurred between the origins of the air, its initial sampling by the DC-8, and later sampling by the C-130. Follow- on chemical modeling that will be conducted in collaboration with NASA Langley Research Center also will be described.
DE: 0365 Troposphere: composition and chemistry
DE: 0368 Troposphere: constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting