Atmospheric boundary-layer gravity wave observations in the Netherlands

Over last few years we have observed tens of atmospheric gravity wave (GW) events on our operational network and research instruments in The Netherlands, including the North Sea. These events are ducted GWs that are trapped in the stable boundary layer and propagate horizontally, characterized by a near-monochromatic wave with vertical velocity amplitudes up to a few m/s, a period of a few minutes, a duration of one hour or more, and a spatial extent on the order of 100 km or more. The origin of those GWs are non-orographic, and likely linked to weather fronts. These GWs can lead to a strong modulation of wind, temperature and humidity in the lower 100m’s of the atmosphere.

We observe these GWs by various instruments, including Doppler lidars, automatic lidar ceilometers, weather radars, (tower) in-situ sensors and microbarometers that are part of the KNMI synoptic observation network, Cabauw atmospheric research station or North Sea wind lidar network. Together they provide 3D information on mesoscale GWs, including vertical profiles, horizontal spatial extent, and evolution during propagation. We have recently highlighted two GW events: in the Netherlands and Belgium in the night and early morning of June 30, 2022 [1], over the North Sea in the night and early morning of May 2, 2025 [2].

Here we give an overview of our research on boundary-layer GW observations. We explore the occurrence, properties and impact of those GW events in the Netherlands, both onshore and offshore. These comprehensive sets of observations may serve as a testbed for high resolution weather models that aim to capture mesoscale GW events and the effect they have on the (lower) atmosphere. The siting of our North Sea wind lidars, i.e., in the middle of large offshore wind farms, provides the possibility to study the effect of GWs on wind farm performance.

[1]  Knoop S, Assink J D, Leijnse H, Tijm S, de Haij M J, Bosveld F C, Theeuwes N E, Evers L G, Unal C and Laffineur Q, “High-resolution observations of a mesoscale gravity wave event in the nocturnal boundary-layer over The Netherlands and Belgium”, submitted to Journal of Geophysical Research: Atmospheres (preprint on https://doi.org/10.22541/essoar.176478826.60490095/v1)

[2] Knoop S, Assink J D, de Haij M J, de Jong M, “Doppler lidar gravity wave observations within North Sea wind farms”, to be published in Journal of Physics: Conference Series (Torque 2026)