EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

The impact of London on a low-level jet

Aristofanis Tsiringakis1,2, Natalie Theeuwes2, Janet Barlow3, and Gert-Jan Steeneveld1
Aristofanis Tsiringakis et al.
  • 1Wageningen University & Research, Meteorology and Air Quality Section, Wageningen, Netherlands
  • 2Royal Netherlands Meteorological Institute (KNMI), De Bilt, Netherlands
  • 3Department of Meteorology, University of Reading, Reading, UK

The low-level jet (LLJ) is an important phenomenon that can affect (and is affected by) the turbulence in the nocturnal urban boundary layer (UBL). We investigate the interaction of a regional LLJ with the UBL during a 2-day period over London. Observations from two Doppler Lidars and two numerical weather prediction models (Weather Research & Forecasting model and UKV Met Office Unified Model) are used to compared the LLJ characteristics (height, speed and fall-off) between a urban (London) and a rural (Chilbolton) site. We find that LLJs are elevated (70m) over London, due to the deeper UBL, an effect of the increased vertical mixing over the urban area and the difference in the topography between the two sites. Wind speed and fall-off are slightly reduced with respect to the rural LLJ. The effects of the urban area and the surrounding topography on the LLJ characteristics over London are isolated through idealized sensitivity experiments. We find that topography strongly affects the LLJ characteristics (height, falloff, and speed), but there is still a substantial urban influence.

How to cite: Tsiringakis, A., Theeuwes, N., Barlow, J., and Steeneveld, G.-J.: The impact of London on a low-level jet, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11307,, 2021.


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