Publication Date:
2017-10-17
Description:
The Airborne imaging differential optical absorption
spectroscopy (DOAS) instrument for Measurements of
Atmospheric Pollution (AirMAP) has been developed for the
purpose of trace gas measurements and pollution mapping.
The instrument has been characterized and successfully operated
from aircraft. Nitrogen dioxide (NO2) columns were
retrieved from the AirMAP observations. A major benefit of
the push-broom imaging instrument is the spatially continuous,
gap-free measurement sequence independent of flight
altitude, a valuable characteristic for mapping purposes. This
is made possible by the use of a charge coupled device (CCD)
frame-transfer detector. A broad field of view across track
of around 48� is achieved with wide-angle entrance optics.
This leads to a swath width of about the same size as the
flight altitude. The use of fibre coupled light intake optics
with sorted light fibres allows flexible instrument positioning
within the aircraft and retains the very good imaging capabilities.
The measurements yield ground spatial resolutions
below 100m depending on flight altitude. The number of
viewing directions is chosen from a maximum of 35 individual
viewing directions (lines of sight, LOS) represented
by 35 individual fibres. The selection is adapted to each situation
by averaging according to signal-to-noise or spatial
resolution requirements. Observations at 30m spatial resolution
are obtained when flying at 1000m altitude and making
use of all 35 viewing directions. This makes the instrument
a suitable tool for mapping trace gas point sources and
small-scale variability. The position and aircraft attitude are
taken into account for accurate spatial mapping using the
Attitude and Heading Reference System of the aircraft. A
first demonstration mission using AirMAP was undertaken
in June 2011. AirMAP was operated on the AWI Polar-5
aircraft in the framework of the AIRMETH-2011 campaign.
During a flight above a medium-sized coal-fired power plant
in north-west Germany, AirMAP clearly detected the emission
plume downwind from the exhaust stack, with NO2 vertical
columns around 2�1016 molecules cm
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
Permalink