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For the near-surface winds over the ocean, many model products and satellite footprints have spatial resolutions on the order of tens of kilometers. I'm interested in knowing how much the winds (both magnitude and direction) are expected to vary over tens of kilometers, at a single instant in time.

Of course, this will depend on a variety of factors - such as if a storm is passing by, distance from the coastline, precipitation etc. I'd be happy to hear about rough numbers in all conditions, but I'm especially interested in the open ocean in both hurricane and non-hurricane conditions.

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    $\begingroup$ There are various wind models used for predicting winds for navigation. These models take into account predicted weather. Different models will have different grid resolutions. weather.eos.ubc.ca/wxfcst gives wind predictions for specific times at 12 km grids. Also there are web products that will give you predicted winds (free) at grid resolutions over 10s of km, for example: sailflow.com $\endgroup$ – Friddy Oct 14 '15 at 21:04
  • $\begingroup$ Thanks @Friddy - I logged in and saw your comment just now. I'm going through the links...but I'm wondering if there are models or theories on even finer, sub-kilometer grid variability, say on the order of meters, 10's, and 100's of meters. I'm mostly interested in the horizontal (u and v) winds. $\endgroup$ – user4624937 Oct 18 '15 at 6:47
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    $\begingroup$ I haven't seen models with finer granularity. If there were such models I would expect that the range over which they are valid would be smaller, in addition I would expect that they would be very sensitive to variations in the amount of wind in the input model. You might want to look at wind models used to predict fire spread for smaller granularity for the wind. As far as marine use is concerned 10 km grid is usually sufficient and other than a strong cold front or thunder storm vertical wind is generally not a factor. $\endgroup$ – Friddy Oct 19 '15 at 23:39
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    $\begingroup$ Okay - I'll look into these wind models. One question @Friddy: you say "10 km grid is usually sufficient" for marine use - I don't doubt this (this appears to be the consensus in community), but does there in fact exist some justification for this sufficiency? Maybe papers or book chapters you can think of? Thanks in advance. $\endgroup$ – user4624937 Oct 20 '15 at 9:02
  • $\begingroup$ My response is just from personal experience, for me, a kayaker, and for most powered vessels the largest issue is swell and wind wave that results from the wind (the force of wind affects me too but by then the seas can be large). For waves to develop they need fetch, an upwind expanse of open water. The shortest fetch to produce any significant wave is about 12 miles, see the chart mid page en.wikipedia.org/wiki/Swell_(ocean). Without too much detail the only interesting variations in wind appear to be near shore. $\endgroup$ – Friddy Oct 21 '15 at 15:56

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