Hurricane Wind Ratings - Question

[stu]

I have been having an Email discussion with Derek Ortt – and I thought that it would be interesting to move it over to Storm2K for further discussion.

Basically we were mussing over the effects of the forward speed of a hurricane and how this reduces wind speed in the left front quad etc etc.

We rate land falling Hurricanes (Where possible) with fixed position land based Anemometers as well as fixed position Doppler Radar.

One question that I can not quite grasp is how does a REKON aircraft measures hurricane winds given that it is constantly moving and therefore can not calculate sustained winds over one minute for a fixed location. Unless they only deal with gusts.

I would assume that the aircraft knows is forward speed and direction via GPS and by using maths can work out the wind speed that the aircraft is sampling.

The same must go of a drop sonde – the sonde must know its forward speed over ground in order to calculate the wind speed – but again surly this can only measure gusts and not sustained?

[thunderchief]

airplanes indeed can use navigation systems to determine the wind based on the difference between airspeed/heading and groundspeed/course. I dont know for sure what length of time is used by the plane(I seem to remember 10 seconds somewhere).

The dropsonde I beleive has its "wind" measured from the plane, using a direction/rangefinder tracking the drops radio.


EDIT: winds aloft are usually relatively gust free, compared with what is measured at the surface amongst all kinds of mechanical turbulence.

[Charles-KD5ZSM]

The recon planes, i am pretty sure, use measure the wind for about a minute or more.