Airborne Laser Infrared Absorption Spectrometer (ALIAS-II) for in situ atmospheric measurements of N_(2)O, CH_(4), CO, HCI, and NO_(2) from balloon or remotely piloted aircraft platforms

摘要

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 (180 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 HCI 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 ≤3s, 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.