Monitoring the composition of the Earth's atmosphere
Scientist satellite remote sensing at KNMI

On 17 March 1999 I started on a post-doc. job for a period of five years at the Royal Netherlands Meteorological Institute (KNMI), in the research division then called Atmospheric Composition, later names Climate Observations.

Within this division I have been involved in several aspects of monitoring atmospheric trace gases. The work is research related to retrieval and assimilation of data gathered by satellites to obtain, for example, profiles (vertical distributions) and total values of ozone or other species in the Earth's atmosphere. The methods developed are relevant for various satellite missions (e.g. the ozone monitoring instruments GOME, SCIAMACHY, OMI, GOME-2 -- see a separate page for the meaning of these names).
The main thing I worked on first was to provide a better wavelength calibration of the spectra measured by GOME using a Solar reference spectrum. This is necessary for GOME on the one hand because GOME's calibration lamp could be failing at any moment, and on the other hand the retrieval of ozone profiles requires a calibration which is more accurate. The method is also relevant for later missions, such as OMI and GOME-2.

[GomeCal logo] This new wavelength calibration has been converted, together with some other corrections, into a software package called GomeCal. Other users of GOME data can use the package to re-calibrate the measured spectra. The package was released in 2003 via the GomeCal home page at the GOME Fast Delivery website of KNMI.

Additionally, I took part in retrieving an Aerosol Absorption Index (AAI) based on GOME measurements and briefly tried my luck on retrieving concentrations of sulphur dioxide (SO2), which comes into the atmosphere e.g. due to antropogenic polution and volcano eruptions, as a test of the method developed by others.

[GOFAP logo] The work was first part of a project called GOFAP.
That project was set up to create a GOME Fast Delivery Service [the website of which has been deleted around 2010], to provide ozone columns, ozone profiles and assimilated global ozone maps from GOME data on a near-real time bases, i.e. within 3 hours after the measurement (the nominal delivery of total ozone columns from GOME is between two weeks and two months after acquisition).
The results of such fast delivery services can be used for improving numerical weather prediction models, radiation and UV forecasts and ozone measurement experiments.
Some additional information on ozone:

===> The 1999 ozone hole as seen by GOME (110 kb)
           (there will be no such page on the ozone hole of other years)
===> About ozone and the formation of the ozone hole
[TEMIS logo] The work was continued and further extended within the project TEMIS. The aim of the project is the delivery of tropospheric trace gas concentrations (such as ozone, SO2 and NO2), and aerosol and UV products, derived from observations of the nadir-viewing satellite instruments, such as GOME and SCIAMACHY. My work within TEMIS was mainly devoted to the main pages of the TEMIS website, some web-tools there, and processing and analysis of UV index and UV dose data.


End of contract and follow-up

My work at KNMI ended on 17 March 2004.
On 1 June 2004 I started at the Belgian Institute for Space Aeronomy
to continue work in the same field, initially also the TEMIS project.
On 1 June 2011 I returned to KNMI

===> 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
[KNMI logo]
Royal Netherlands Meteorological Institute (KNMI)
Climate Research and Seismology Department
Atmospheric Composition Research Devision
P.O. Box 201
3730 AE   De Bilt
The Netherlands
visiting address:   Wilhelminalaan 10, De Bilt

[DUP logo] By the way:
Both the GOFAP and the TEMIS projects are funded by the European Space Agency (ESA) via their Data User Programme (DUP).
[ESA logo]

Jos van Geffen -- Home  |  Site Map  |  Contact Me

created: 17 March 1999
last modified: 28 November 2014