FrictionVelocity (1) is an intermittent venture in blogging about a life in atmospheric & ocean science; mostly the (occasionally) weird and (sometimes) wonderful bits of it that involve making measurements in the wild. Primarily the fault of Ian Brooks, it features contributions from members of my research group at the University of Leeds, and our collaborators at the National Oceanography Centre in Southampton..

Our research is based around measurements of physical processes in the atmosphere and ocean, in particular turbulent exchange processes. These measurements are often made in remote parts of the world, and not infrequently under rather extreme weather conditions. Making measurements on an Arctic ice floe, or at sea in a storm is usually hard, and occasionally miserable; it is also a great privilege, providing opportunities to go places and to see and do things that very few people get. Being at sea in a force 12 wind with waves up to 17m high isn’t something I would necessarily recommend, but it’s a hell of a ride.

Friction Velocity (2) a scaling velocity used in studies of turbulent flow, usually represented by the symbol u*, it is proportional to the turbulent wind stress – the loss of momentum from the wind due to friction at the surface.


Contributors:

Ian Brooks is a boundary-layer meteorologist and senior lecturer in the Institute for Climate & Atmospheric Science within the School of Earth & Environment at the University of Leeds. A physicist by training, I studied thunderstorms for my PhD, moved sideways to study marine stratocumulus clouds, have slowly worked my way down towards the ocean surface, and have recently been venturing into the water. I may yet end up as an oceanographer. My other major research interest is in Arctic boundary layer and cloud processes.

Sarah Norris is a post-doctoral research fellow at Leeds. She has a degree in ‘proper’ meteorology;  started studying sea-spray aerosol fluxes for her PhD and still hasn’t escaped. She is the longest serving member of the group, and much prefers being in the field than stuck in front of a computer back in the office (and who can blame her).

Rebecca Jansen is currently between degree programmes – she completed a masters in Physics of the Earth and Atmosphere in 2011, and will be starting a PhD in October 2012, studying Arctic boundary layer cloud processes. In the mean time she’s (mostly) analyzing data on ocean whitecaps for the the WAGES air-sea interaction project.

Guests Contributors for the Arctic Ocean 2016 expedition

Anna Fitch is a climate modeller at SMHI.

Piotr Kupiszewski recently completed his PhD at ETH Zurich, and is running aerosol and fog sensors for research at MISU during the AO2016 cruise.

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2 comments
  1. Bill Rust said:

    Where did you get definition 2 of friction velocity. I’m documenting a wind erosion model and I’m trying to understand how observed wind velocity relates to friction velocity. I have code that does something but it is not well documented as to what so I am floundering and would appreciate any enlightenment that you might have.

    • It’s a widely used scaling term in boundary layer meteorology. See for example the definition in the AMS Glossary. Definition (2) is rather simplified, strictly u* = (tau^0.5)/rho where tau is the turbulent wind stress and rho is air density.

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