Of course it changes direction, it's a convective circulation.  Wind will come in towards the cloud bands, go up during which the clouds are formed, then diverge above the clouds.  Look for any image of hurricane structure, it's not a simple merry-go-round.  Due to Coriolis effects the convergence/divergence pattern will twist in different directions.

I have to ask why you are asking, it looks as though you have read nothing about storm structure, or the question would not have come up.  If you put your question in context you may get a more useful answer.

I see what you mean, perhaps the question was poorly stated. You are correct, I am not well read in storm structure though I have a basic understanding of the movement of air described above. I am not interested in the macro-structure, just near the sea surface.

Lets confine the conversation to very close to the sea surface. Say you are at the ocean surface on the the right hand side the hurricane eye, in the northern hemisphere the the mean wind direction you measure is southerly. Now, beginning at the same location, you have a vertical profile up to 1 km, would you expect southerly winds all the way up, or would expect some deviation of this?

Of course it changes direction, it's a convective quasi-circulation. Wind vector will come in towards the cloud bands, go up during which the clouds are formed, then diverge above the clouds. Look for any image of hurricane structure, it's not a simple merry-go-round. Due to Coriolis effects the convergence/divergence pattern will twist in different directions.

I have to ask why you are asking, it looks as though you have read nothing about storm structure, or the question would not have come up. If you put your question in context you may get a more useful answer.

I see what you mean, perhaps the question was poorly stated. You are correct, I am not well read in storm structure though I have a basic understanding of the movement of air described above. I am not interested in the macro-structure, just near the sea surface.

Lets confine the conversation to very close to the sea surface. Say you are at the ocean surface on the the right hand side the hurricane eye, in the northern hemisphere the the mean wind direction you measure is southerly. Now, beginning at the same location, you have a vertical profile up to 1 km, would you expect southerly winds all the way up, or would expect some deviation of this?

Look into the Eckman profile.  It tells you what winds do as a function of altitude when surface friction, turbulence and the Coriolis effect is taken into account.  Winds closer to the surface will tend more towards the local low pressure center (which may be a cloud band or the eye), as they get higher they tend more perpendicular due to the Coriolis effect.  The exact profile from theory doesn't work perfectly but there's no inherent reason why hurricane winds will act different from any other winds.

If you think of a hurricane as a rotation cylinder of air then the wind direction will be tangential to the side of the cylinder. That tangent will have the same direction at any point on a line running vertically from the surface. Thus if you approximate a hurricane to a cylinder the wind direction will be constant with height. The Eckman profile only applies to a  unidirectional wind, not a circulating one.

A typhoon-like vortex solution of incompressible 3D Euler equations, Theor. Appl. Mech. Lett. 1. 042003. http://dx.doi.org/10.1063/2.1104203

I have to respectfully disagree with Alastair McDonald's reply.  The upper air away from the surface does of course follow the cylindrical circulation (so long as you are still low in the atmosphere).  But the question is about wind close to the surface, which is governed not only by the pressure gradient and coriolis effects of the upper air, but also frictional effects from the surface.

The Eckman calculation is single column, and is indifferent to the large scale circulation.  In a low pressure system you see the effects as air near the ground cuts across the pressure contours at nearly 45 degrees, but upper air follows the pressure contours.  A hurricane is just a massive low pressure system.  The Eckman profile holds at each location, so that the wind near the ground inclines towards the local low pressure (not directly towards it) while higher  air will circulate perpendicular to the pressure.  Higher still the wind becomes vertical, then eventually switches to circulating the opposite direction.  But all this higher stuff is not Eckman circulation, and does not pertain to the question about surface winds.  About a km high the air is moving around the local low pressure; below it begins to turn so that near the ground it has a component towards the low pressure.

Over ocean, the friction is low ccmpared to land, so near the surface the wind will be closer to circulating around the low pressure than over land, but will still have a component towards the low pressure.

And of course, the Eckman profile is only as good as the turbulence parameterization, but the basic idea of friction causing wind near the surface to have a component towards the low pressure is still true.

Brian,

Yes, of course you are correct. I was ignoring the fact that the air is rising. For that to happen air must flow towards the centre of the hurricane at the base to feed the updraught. 

Close to the surface, it may also depend on you radial distance from the hurricane eye. Check out the following:

Smith, R. K. and Montgomery, M. T. (2014), On the existence of the logarithmic surface layer in the inner core of hurricanes. Q.J.R. Meteorol. Soc., 140: 72–81. doi: 10.1002/qj.2121

They discus various models for inner core dynamics, differing in various assumptions and simplifications. As the author notes:

"...the schemes indicate that a significant turning of the wind vector with height occurs in the lowest few hundred meters, a property that cannot be represented by the traditional log layer."

If outside the core a traditional log layer was appropriate then perhaps one would not expect turning of the wind vector, but of course at some point a transition layer must exist which connects the surface layer to the upper layer.

So if you are traveling radial outward from the center of the eye you would encounter 4 zones: 1) calm eye, 2) inner core (most intense region governed by dynamics outlined in the reference above), 3) outer core (some simplifying assumptions may be made so that a log layer may be sufficient), and 4) outside the hurricane (ambient conditions).

http://onlinelibrary.wiley.com/doi/10.1002/qj.2121/abstract

the log layer referred to is the Eckman profile, with a very simple turbulence parameterization.  If the turbulence changes character you'll diverge from the log profile.  this is getting into fairly advanced stuff, and there is no firm consensus as yet.  A 2014 paper may serve you well - but the mathematics may be complex!

In a hurricane the wind direction change is on the order of < 10 deg in the lower 150 m and then increases to about 25 deg at the typical flight level of 3 km.  

If you carefully examine mean boundary layer wind profiles from GPS dropsonde data (including hodographs in the Smith and Montgomery article) the change in the wind direction is pretty small (

I guess I've been relaxing too much in retirement, & haven't been giving my routine lectures on "Stop Using the Simplistic Linear Closure for the PBL" ;Dec. AGU, 2013.   It has long been known that the Ekman turning is unstable to infinitesimal perturbations (and there are lots of those);  BUT it comes to equilibrium in a modified nonlinear solution; see Brown, 1970 etc, Analytic Methods in Planetary Boundary Layer Modeling, Adam Hilger LTD., London, and Halstead Press, John Wiley and Sons, New York. 150 pp, 1974. (Translated to Russian, Chinese, Korean, 1980); Etling & Brown A Review of Large-Eddy dynamics in the Planetery Boundary Layer, Bound.-Layer Meteor., 65, 215-248, 1993.  Diagnosis of frontal instabilities over the Southern Ocean, Patoux, J., G.J. Hakim and R.A. Brown, Monthly Weather Review, April, 2005, 863-875.  The profiles look much like those observed by Mark.

I know, it's a lot more complicated than Ekman's 1905 solution (which I taught the first hour of my quarter long class in PBL dynamics --- the rest of the quarter was devoted to the nonlinear solution), but it's much better than the obsolete summaries of 1973 & 1984. This has been shown by Patoux et. al (Brown, Foster, and others that include significant improvement in prognostic fields by NCEP) in several papers, e.g.: Diagnosis of frontal instabilities over the Southern Ocean, Patoux, J., G.J. Hakim and R.A. Brown, Monthly Weather Review, April, 2005, 863-875; & Patoux, J., R.C. Foster and R.A. Brown, 2010: A method for including mesoscale and synoptic-scale information in scatterometer wind retrievals, Journal of Geophys. Res, 115. 2010.

There is also the centrifugal force on this flow that can be an instability factor, it produces the same finite perturbation equilibrium vortex flows, or organized large eddies, which have also have a nonlinear solution.

I know this is bad news for many, but please don't blame the messengers. It's the mathematics.