Martijn Schaap

Researcher air quality

Major environmental challenges of the 21st century relate to the composition of our atmosphere. Exposure to pollutants such as particulate matter is associated with significant health impacts. Deposition of atmospheric reactive nitrogen causes a loss of biodiversity in ecosystems through eutrophication.

Research area

In addition, emissions of long lived greenhouse gases and short lived climate forcers drive global and regional climate change. Besides common sources in energy production, agriculture and material and food consumption, the fate and impact of many pollutants are intertwined through processes in the atmosphere. The complex interactions call for an integrated approach to develop cost effective mitigation strategies.

As mitigation strategies are becoming increasingly expensive, the demand for high quality information on the state of the environment, the origin of the pollution and the effectiveness of potential measures become more and more important.

Recent results

My research focuses on improving the quality of chemistry transport models to meet these demands for particulate matter and reactive nitrogen. Specific attention is given to developing new modelling techniques to detail the meteorological dependencies of anthropogenic emissions and the use of novel satellite data to verify emission strengths. During the last three years we provided a 15 year reanalysis of nitrogen deposition for Germany.

The modelled dry deposition with LOTOS-EUROS showed good correspondence to novel flux measurements in the Bavarian Forest. In collaboration with Wageningen University an emission module for agriculture was developed which aims to forecast crop dependent manure application across north-western Europe.

Detailed evaluation of different set-ups connecting LOTOS-EUROS to the German weather model COSMO revealed that moving to a different vertical structure better captured observed pollutant variability, which was later confirmed by evaluation against Spanish ozone campaigns and against TROPOMI-NO2 satellite data.

First results of the assimilation of TROPOMI-NO2 yields a better correspondence of modelled ground level concentrations with observations and hints at an underestimation of emissions in the east of Germany. Finally, we have devoted attention to the validation of source apportionment techniques for particulate matter and nitrogen oxides.

PhD supervision

  • Joscha Pültz (FU-B internal funding)
  • Markus Thürkow (German Government funding)
  • Pascal Wintjen (German Government funding) – Together with Dr. Christian Brummer (vTI)
  • Xinrui Ge (NWO) – together with promotor Wim de Vries (WUR)
  • Shelley van der Graaf (NWO) - together with promotor Jan-Willem Erisman (VU) – defended her thesis on 12-01-2022

Top publications

  • Wintjen, P., Schrader, F., Schaap, M., Beudert, B., and Brümmer, C. (2022), Forest–atmosphere exchange of reactive nitrogen in a remote region – Part I: Measuring temporal dynamics, Biogeosciences, 19, 389–413,
  • Thürkow, M., Kirchner, I., Kranenburg, R., Timmermans, R. M. A., & Schaap, M. (2021). A multi-meteorological comparison for episodes of PM10 concentrations in the Berlin agglomeration area in Germany with the LOTOS-EUROS CTM. Atmospheric Environment, 244.
  • Super, I., Dellaert, S.N.C., Tokaya, J.P., Schaap, M. (2021), The impact of temporal variability in prior emissions on the optimization of urban anthropogenic emissions of CO2, CH4 and CO using in-situ observations, Atmospheric Environment: X, 11, 100119,
  • Belis, C. A., Pernigotti, D., Pirovano, G., Favez, O., Jaffrezo, J. L., Kuenen, J., … Yubero, E. (2020). Evaluation of receptor and chemical transport models for PM10 source apportionment. Atmospheric Environment: X, 5.
  • Daellenbach, K. R., Uzu, G., Jiang, J., Cassagnes, L. E., Leni, Z., Vlachou, A., Schaap, M., … Prévôt, A. S. H. (2020). Sources of particulate-matter air pollution and its oxidative potential in Europe, Nature, 587 (7834), 414–419.
  • Ge, X., Schaap, M., Kranenburg, R., Segers, A., Jan Reinds, G., Kros, H., & De Vries, W. (2020). Modeling atmospheric ammonia using agricultural emissions with improved spatial variability and temporal dynamics. Atmospheric Chemistry and Physics, 20(24), 16055–16087.
  • Manders, P. Builtjes, L. Curier, L., ..., and M. Schaap, M., “Curriculum vitae of the LOTOS–EUROS (v2.0) chemistry transport model”, Geosci. Model Dev., 10, 4145–4173,, 2017.


Princetonlaan 6
NL-3584 CB Utrecht

Postal address

P.O. Box 80015
NL-3508 TA Utrecht