Following the successful Twin Otter flights in 2008 and 2009, a completely redesigned AMAX-DOAS pylon was deployed aboard the NOAA Twin Otter for the CalNex and CARES field campaign in 2010 in California. A total of 52 research flights (204 flight hours) were conducted over the course of two months. The purpose of the CU AMAX-DOAS deployment was to measure horizontal and vertical distributions of nitrogen dioxide (NO2), formaldehyde (HCHO), glyoxal (CHOHO) and aerosol extinction over California, particularly over the South Coast Air Basin (SoCAB), characterize boundary conditions for comparison with atmospheric models, and probe for pollutant concentrations above the boundary layer.

The plane was equipped with a suite of remote sensing instruments: the University of Colorado deployed (1) CU AMAX-DOAS instrument, (2) two 4-channel radiometers (zenith and nadir viewing) to measure surface albedo (SA); further, NOAA/ESRL/CSD deployed (3) a nadir-pointing Tunable Ozone Profiler for Aerosol and oZone (TOPAZ) lidar, which measures vertical distribution of ozone (O3), and the (4) University of Leeds HALO Doppler lidar, which measures 3-dimensional wind fields, as well as (5) a nadir pointing infrared pyrometer, and (6) an in-situ Omonitor.
(A) NO2 vertical column measured by CU AMAX-DOAS during one of the research flight in CalNex 2010. (B) Time trace of flight altitude (blue), ground altitude (black) and SZA (green) from the same flight.


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Twin Otter flight tracks during CalNex and CARES 2010.