Monitoring the composition of the Earth's atmosphere
Scientist satellite remote sensing at KNMI
On 1 June 2011 I returned to the Royal Netherlands Meteorological Institute
(KNMI), after having been there
during 1999-2004 and at the
Belgium Institute of Space Aeronomy (BIRA-IASB)
The research division I am in at KNMI is called Climate Observations.
The satellite instrument TROPOMI ("Tropospheric Monitoring Instrument")
has been developed by industrial parties for launch in 2016 on board
of the European GMES Sentinel-5 Precursor satellite, and will act as the
successor of OMI ("Ozone Monitoring Instrument") aboard the NASA satellite
EOS-Aura (2004-present). KNMI has the scientific lead for the TROPOMI
instrument and fulfils the role of Principal Investigator (PI) institute for
this international mission, as it also does for OMI.
The TROPOMI mission objective is to monitor the troposphere for scientific
research and in support of services to society. Measurements are taken down
to the Earth's surface with sufficiently high resolution in both space and
time, in order to be able to quantify anthropogenic and natural emissions,
and to quantify atmospheric life cycles of trace gases and aerosol particles
which have an impact on air quality and climate forcing from the regional to
the global scale.
[Adapted from Dobber et al., 2008]
For this TROPOMI mission I play a role in the team that works on the
definition and development of the TROPOMI algorithms for trace gas, aerosol
and cloud data products, and of the operational TROPOMI software.
In addition to the development of new algorithms, this team also maintains
and improves existing algorithms for OMI -- in close collaboration with the
teams working with data from other satellite instruments (notably SCIAMACHY,
- See for more information on the main projects:
Nitrogen dioxide (NO2)
My main focus is the algorithm for the retrieval of concentrations of
nitrogen dioxidd (NO2), a key element of air quality issues -- NO2 in the
atmosphere originates from anthropogenic (i.e. man-made) sources and from
natural processes: fossil fuel combustion, biomass burning, soil release,
For TROMOPI my work involves development of the algorithm, based on an
existing NO2 algorithm for OMI. At the same time the OMI algorithm is being
improved. This work is done in close with researchers from other institutes
and within the framework of international projects.
The work on NO2 for OMI and TROPOMI also connects me to the
The image on the right shows the NO2 concentration in the troposphere over
Europe as derived from OMI measurements, averaged over September 2011.
See for more information on NO2, data and maps the
UV index & UV dose
Since the second half of 2015 for a small part of my time I returned
to an old favourite:
UV index and UV dose data.
It was time to implement a few improvements to the data processing system:
higher spatial resolution, more recent background input data, improved
cloud correction, improved error estimates, etc.
The image on the left shows the UV index over Europe as derived from
ozone measurements of the GOME-2 instrument.
[Source: TEMIS website]
In addition I play a supportive role in the KNMI contribution to the
international GLOBE project regarding the topic "measurements of aerosol
concentrations", helping e.g. with processing the data.
The Global Learning and Observations to Benefit the Environment (GLOBE)
program is a worldwide hands-on, primary and secondary school-based science
and education program. GLOBE's vision promotes and supports students,
teachers and scientists to collaborate on inquiry-based investigations of
the environment and the Earth system working
in study and research about the dynamics of Earth's environment.
Aerosols are small particles (dust, sand, etc.) and droplets floating in the
air. Aerosols contribute to the greenhouse effect and climate change, and
they can cause breathing problems. For this reason aerosol concentrations
are monitored by satellite and ground based instruments. Within GLOBE pupils
can contribute to the understanding of aerosol concentrations by taking
daily measurements of the sunlight.
For GLOBE Netherlands KNMI coordinates the aerosol measurements and
uses the data for comparisons with satellite measurements.
- See for more information on GLOBE:
Furthermore I have contributed to the educational material made by KNMI in
relation to the GLOBE Aerosol activities. And I have contributed to
material for "Earth Observation and Climate" workshops KNMI occasionally
gives for schools, e.g. in the country-wide framework of science activities
schools ("Wetenschapsweek" and such).
===> list of my publications
about my post-doc. positions in atmospheric research.
See a separate page
for the meaning of some acronyms.
Place of work
Royal Netherlands Meteorological Institute (KNMI)
Climate Research and Seismology Department
Atmosphere and Climate Devision
P.O. Box 201
3730 AE De Bilt
visiting address: Utrechtseweg 297, De Bilt
By the way:
During the period June 2011 - May 2014 I was
officially not employed by KNMI itself but by the KNMI-operated
Stichting Wetenschappelijk Onderzoek (SWO; "Foundation for
Scientific Research" in English).
Since 2 Sept. 2014 I am employed by KNMI -- via the Ministery of
Infrastructure and Environment, of which KNMI is part
(for contractual reasons there had to be a gap between
Jos van Geffen --
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created: 26 May 2011
last modified: 29 July 2016