Alexander van Eijk
In a military context, situational awareness, i.e., an understanding of how well you can see and how well you can be seen, is crucial. Turbulence degrades image quality and absorption by aerosols reduces contrast, which reduces the maximum distance at which you can see.
The research focuses on a small-scale description of atmospheric flow processes, with emphasis on turbulence. For this, we use a series of numerical (weather prediction) tools from coarse to high resolution. This framework is used to model the dispersion of aerosols, in particular those generated at the sea surface, in the lower atmosphere while taking into account the features of the heterogeneous terrain (land-sea transition, orography, etc.). It is our ambition to understand the necessary and sufficient detail of this numerical modeling to optimize computational requirements and the physical footprint that can be handled.
Within TNO, this work is predominantly embedded within DSS but it also relates to other TNO areas: turbulence degrades the quality of (laser) communication systems, and aerosols are important to climate and air quality.
In 2021 an effort was started to implement an aerosol source function in a high-resolution numerical weather model (LES). The spatially resolved aerosol concentrations will be compared to observations made in Le Croisic (France) by optical particle counters and lidar.
Concurrently, aerosol observations made during a cruise in Biskay Bay are analysed to verify the aerosol source function used in the LES. Ongoing projects include the (numerical) modelling of the atmospheric aerosol loading during Haboobs (dust storms) in a remote region of West Africa. The results are expressed in terms of visibility and compared to satellite observations, as few in-situ data is available.
Furthermore, the study of aerosol concentrations in False Bay (South Africa) was continued. Attention is now given to rain events and offshore flow conditions, which mix in aerosols generated by sources over land,
- Faith February, Characterization of aerosol leadings at the southern tip of Africa, University of Cape Town (main supervisor: Katye Altieri) (Government funding)
- Thomas Kociok, Sahara dust Haboobs and effect on visibility - Karlsruhe Institute of Technology (main supervisor: Peter Knippertz) (Funded by Fraunhofer IOSB)
- W. Bruch, J. Piazzola, H. Branger, A.M.J. van Eijk, C. Luneau, D. Bourras and G. Tedeschi (2021). Sea spray generation dependence on wind and wave combination: a laboratory study. Boundary Layer Meteorol.
- Tedeschi, G., A.M.J. van Eijk, J. P. Piazzola and J.T Kusmierczyk-Michulec (2017). Influence of the surf zone on marine aerosol concentration in coastal area. Boundary-Layer Meteorol., 163:327–350, doi:10.1007/s10546-016-0229-7
- Calmet, I, P.G. Mestayer, A.M.J. van Eijk and O. Herlédant (2017). A coastal bay summer breeze study. Part 2: High-resolution numerical simulation of sea-breeze local influences. Boundary-Layer Meteorol. 167:27-51, doi: 10.1007/s/10546-017-0319-1