title: Airborne laser infrared absorption spectrometer (ALIAS-II) for in situ atmospheric measurements of N2O, CH4, CO, HCl, and NO2 from balloon or remotely piloted aircraft platforms.
abstract: The Airborne Laser Infrared Absorption Spectrometer II (ALIAS-II) is a lightweight, high-resolution (0.0003-cm(-1)), scanning, mid-infrared absorption spectrometer based on cooled (80 K) lead-salt tunable diode laser sources. It is designed to make in situ measurements in the lower and middle stratosphere on either a balloon platform or high-altitude remotely piloted aircraft. Chemical species that can be measured precisely include long-lived tracers N(2)O and CH(4), the shorter-lived tracer CO, and chemically active species HCl and NO(2). Advances in electronic instrumentation developed for ALIAS-I, with the experience of more than 250 flights on board NASA's ER-2 aircraft, have been implemented in ALIAS-II. The two-channel spectrometer features an open cradle, multipass absorption cell to ensure minimal contamination from inlet and surfaces. Time resolution of the instrument is <or=3 s, allowing rapid in situ measurements with excellent spatial resolution. ALIAS-II has completed successful balloon flights from New Mexico, Alaska, and Brazil providing CH(4) and N(2)O vertical profiles in the tropics, mid-latitudes, and high northern latitudes up to altitudes of 32 km.
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, USA. dcscott@igor.jpl.nasa.gov
authors.forename: D C
authors.initials: DC
authors.lastname: Scott
authors.forename: R L
authors.initials: RL
authors.lastname: Herman
authors.forename: C R
authors.initials: CR
authors.lastname: Webster
authors.forename: R D
authors.initials: RD
authors.lastname: May
authors.forename: G J
authors.initials: GJ
authors.lastname: Flesch
authors.forename: E J
authors.initials: EJ
authors.lastname: Moyer