 |
| Titel |
The Second Cabauw Intercomparison Campaign for Nitrogen Dioxide Measuring Instruments — CINDI-2 — Overview |
| VerfasserIn |
Arnoud Apituley, Michel Van Roozendael, Francois Hendrick, Karin Kreher, Andreas Richter, Thomas Wagner, Udo Frieß |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250146171
|
| Publikation (Nr.) |
 EGU/EGU2017-10177.pdf |
|
|
|
|
|
| Zusammenfassung |
| For the validation of space borne observations of NO2 and other trace gases from
hyperspectral imagers, ground based instruments based on the MAXDOAS technique are an
excellent choice, since they rely on similar retrieval techniques as the observations from orbit.
In both cases, retrievals take into account the light path of scattered sunlight though the
entire atmosphere. Since MAXDOAS instruments are relatively low cost and can be
operated autonomously almost anywhere, they are credible candidates to form a
world-wide ground based reference network for satellite observations. To ensure
proper traceability of the MAXDOAS observations, a thorough intercomparison is
mandatory.
The Cabauw Experimental Site for Atmospheric Research (CESAR) site in centre of The
Netherlands was the stage of the Cabauw Intercomparison of Nitrogen Dioxide Measuring
Instruments (CINDI) in June-July 2009 and again for the second campaign, CINDI-2, in
2016. Cabauw was chosen because the flat terrain offered a free view of large parts of the
horizon, needed to accommodate the viewing geometry of the MAXDOAS observations. The
location is under influence of both clean as well as polluted airmasses. This gives a wide
range of possible trace gas concentrations and mixtures. Furthermore, at CESAR a wide
range of observations are routinely carried out that fulfil the requirement to provide the
background necessary for unraveling the differences between the observations from different
MAXDOAS instruments that can be quite diverse in design and data treatment. These
observations include parameters needed to understand the light paths, i.e. in-situ aerosol
observations of optical and microphysical properties, as well as vertical profiles of
aerosol optical properties by (Raman) lidar. In addition, vertical profiles of NO2
could be measured during CINDI-2 using the unique NO2 sonde, and a NO2 lidar
system.
With the imminent launch of Sentinel-5 Precursor/TROPOMI, with a nadir pixelsize of
3.5 × 3.5 km2, and recent developments in MAXDOAS instruments there was a need for
CINDI-2. This campaign was completed in September 2016 and had the goals
to:
To assess the consistency of slant column measurements of key target species
(NO2, O3, O2O2 and HCHO) relevant for the validation of S5P and the future
ESA atmospheric Sentinels, from a large number of DOAS and MAXDOAS
instruments from all over the world,
to study the relationship between remote-sensing column and profile
measurements of those species and reference measurements of the same species,
and
to investigate the horizontal representativeness of MAXDOAS measuring
systems in view of their use for the validation of satellite tropospheric
measurements on the scale of 25-50 km2.
A feature of recent MAXDOAS developments is the use azimuthal scanning, in
addition to elevation scanning such as in e.g. the PANDORA type of instruments.
This, and the number of participating instruments, that expanded to 42, posed a
challenge to the design of the CINDI-2 campaign. To support the campaign goals, NO2
profiles were again provided by NO2 sondes and lidar, as well as through in-situ
observations using the Cabauw meteorological tower. Extensive aerosol information was
gathered using Raman aerosol lidar as well as by in situ samplers. The analysis
of the CINDI-2 data is ongoing. In the presentation a campaign overview will be
given.
http://www.cesar-observatory.nl
http://www.tropomi.eu/science/cindi-2 |
|
|
|
|
|
|