Agenda of the Meteorology and Air Quality Group

MAQ Colloquium announcement

10 May 2021, 16.00 - 16.40 uur Teams

Speaker: Arjan Willemse (MSc thesis)

Title:  will follow

Abstract: will follow


Supervisor: Gert-Jan Steeneveld.

MAQ Colloquium announcement


10 May 2021, 16.40 - 17.15 uur Teams

Speaker: Timo Schreurs (MSc thesis)

Title:  An O3 Penalty for Reducing NOx Emissions?
Estimating trends in the Formaldehyde-to-NO2 Ratio over the
Netherlands to evaluate photochemical O3 production between 2005 and

Abstract: The production of O3 in the lower atmosphere is
controlled by the emissions of its precursors nitrogen oxides (NOx) and
volatile organic compounds (VOCs). With the recent measures to reduce NOx
emissions to create a healthier living environment, there has been less concern
regarding the potential ozone penalty it is accompanied with. This study
assesses the influence of changing emissions in NOx  and
VOCs on photochemical O3 production
during summer over the Netherlands and northwestern Europe between 2005 and
2019. Tropospheric column densities of both NO2 and HCHO derived by
OMI are used and combined into the Formaldehyde-to-NO2 ratio (FNR),
which is an indicator for the production regime of O3 (NOx-saturated/NOx-limited).
With decreasing OMI NO2 columns and annually variable but overall
consistent HCHO columns, we observe an increase in FNR over time. At the same
time, surface measurements indicate a rise in summertime O3 concentrations. To evaluate the
changes in the summertime chemical regime for O3
production, CLASS model experiments are set-up to reproduce the observed HCHO
and NO2 column densities and Osurface
measurements. Based on the model experiments, O3 mixing ratios
increased on average by 10 ppb between 2005 and 2019 due to an increase in FNR.
After the implementation of entrainment from the free troposphere, this
increase reduced to 3 ppb due to a reduction in free tropospheric O3.
Although the influence of entrainment suggests a dampening effect on a rise in
O3, the annual mixing ratios in the boundary-layer increased by 8
ppb in 2005 and 1 ppb in 2019, of which the contributions of the FNR and
entrainment correspond on average to 90% and 10% respectively. 

Supervisor: Folkert Boersma

MAQ Colloquium announcement


11 May 2021, 16.00 - 16.45 uur Teams

MSc seminar Onno Doensen (organized at University Mainz, Germany)

Title & Abstract: will follow 

Supervisor: Jordi Vila