Four portable instruments (PARIS, MAESTRO-G, SPS-G and DOAS) were
brought to AStrO for the campaign to join two MSC instruments (DA8 FTS
and DIAL) which are permanently located at the observatory. The
measurements from these six instruments were complemented by frequent
ozonesonde flights from the Eureka Weather Station.
MSC DA8 Fourier Transform
Infrared Spectrometer (DA8 FTS)
The primary instrument for the campaign is the DA8 Fourier transform
infrared spectrometer (FTS). It was installed at AStrO in 1993. It is
used to record atmospheric absorption spectra in the infrared with an
apodized resolution of 0.004 cm
-1, using the sun as light
source. Liquid-nitrogen-cooled InSb and MCT detectors and several
interference filters are employed to acquire spectra from about 650
cm-1 to 4500 cm
-1. The FTS is
an NDSC-validated instrument with a 10-year data set. Column
amounts of all but one of the ACE baseline species are retrieved from
the FTS spectra.
MSC DA8 at AStrO
Suntracker mirror
on roof of AStrO
Differential Absorption Lidar
(DIAL)
The ozone DIAL system at AStrO has been operated by MSC, CRESTech, and
York University in the past. These measurements provide vertical
profiles of ozone and temperature. Profiles of aerosol and water
vapour are also expected to be retrievable. The DIAL uses a XeCl
laser with hydrogen Raman shifter to provide outputs at 308 nm (the
“on” or ozone absorbed wavelength) and 353 nm (the “off” or
unabsorbed wavelength). A 1-meter Newtonian telescope collects
the
elastic backscattered radiation at these wavelengths as well as the
Raman scattering from atmospheric nitrogen and water vapour.
Ozonesondes
Regular ozonesonde flights are made by MSC once a week from the Eureka
Weather Station. The ozonesondes make in situ measurements of ozone
partial pressure on ascent. Profiles of pressure and temperature
are provided by radiosondes that fly along with the ozonesondes.
For the intensive phase of the campaign (Feburary 22 - March 8), the
frequency of flights was increased to daily.
Charlene preps
the ozonesonde before launch
Keeyoon watches
as Andre and Charlene set up the sonde for launch
Raven balloon waiting
for launch in hydrogen shed
Portable Atmospheric Research
Interferometric Spectrometer (PARIS-IR)
The Portable Atmospheric Research Interferometric Spectrometer is an
adapted version of the ACE-FTS, the high-resolution Fourier transform
spectrometer on board SciSat-1. PARIS-IR uses the radiance from
the Sun to measure atmospheric solar absorption spectra. Vertical
coumn amounts covering almost the same range of species as ACE-FTS
(except for N2O5) w be retrieved from the PARIS spectra. A ZnSe
beamsplitter and HgCdTe and InSb detectors provide wide wavenumber
coverage in the infrared (750 -4100 cm-1). The maximum
resolution of PARIS-IR is 0.02 cm-1.
Front view of PARIS
instrument
Final location of
PARIS
PARIS sharing solar beam
with DA8
MAESTRO-G and SPS-G
The MAESTRO-G spectrometer is a ground-based version of the SciSat-1
MAESTRO instrument. It consists of two independent spectrometers,
operating from 285 to 550 nm and from 525 to 1030 nm. It uses a concave
holographic grating with 1024 pixel photodiode array detector,
providing 1-2 nm spectral resolution. The MAESTRO-G detector is
uncooled, but operation outside on the roof of AStrO should provide
sufficient cooling. Spectra will be collected using both
zenith-sky and direct solar viewing. Total columns of ozone, NO2,
H2O, OClO, BrO, SO2, and aerosol optical depth should be retrievable
from the MAESTRO-G spectra. The SunPhotoSpectrometer (SPS), the
forerunner of MAESTRO, is also included in the campaign. These
instruments have been flown on STS-52, aboard the ER-2 as part of the
NASA Upper Atmospheric Research and High Speed Research Programs and on
the MANTRA 1998, 2000, 2002 balloon flights.
MAESTRO and SPS on
tracker platform
The earlier
verison - the manual "suntracker"
UV-visible Grating
Spectrometer (DOAS)
The University of Toronto UV-visible grating spectrometer records
UV-visible absorption spectra of the light scattered from the zenith
sky. It consists of a triple-grating spectrometer with
diffraction gratings of 400, 600 and 1800 grooves/mm, providing
spectral resolutions of 2.0, 0.9, and 0.5 nm (FWHM). The detector is a
thermoelectrically cooled CCD array. The spectra will be analyzed
using the technique of differential optical absorption spectroscopy
(DOAS) to retrieve vertical columns of O3 and NO2. Vertical profiles of
NO2 will also be derived from the measurements of NO2 slant column
variation with solar zenith angle. The instrument is automated
and will remain at AStrO for the extended phase of the Arctic campaign.
View of grating
spectrometer
DOAS in hatch before
"dome"is installed
