The "thermal wind" does in fact not exist at high level, so that last question is nonsensical.
You could ask either what is the thermal wind, or what is the wind at high level.
Remember that the thermal wind is not in fact a measurable, actual wind, it is merely the term used to describe the
change in wind, usually as a result of changes in air temperature; which cause the isobaric surfaces to slope, thus creating a pressure gradient that changes the wind.
In your example;
09020KT at SFC and 27040KT at say, 12000 feet.
The change in wind is 27060KT (you need to draw this up with vectors), but it might look something like
<-----27040---------o--09020-->
<-----------27060---------------<
So, 27060KT in 12000 ft is 27005KT
pr 1000 feet.
Ie the thermal wind is westerly at 5 kt
pr 1000 feet -- so you would derive the following:
SFC -- 09020KT
1000' -- 09015KT
2000' -- 09010KT
3000' -- 09005KT
4000' -- CALM
5000' -- 27005KT
6000' -- 27010KT
etc.
The easterly flow at the surface could possibly be due to a low pressure to the south in the northern hemisphere. So as we see -- the thermal wind is affecting the wind to the extent of making it 5 knots more westerly for every thousand feet -- this would normally be caused by cold air to the north.
Of course wind patterns could be, and often are, way more complex. I'm sure you've read about high and low pressures, sea and land breezes, and local phenomenons and terrain affecting the wind direction and speed. Such variances are usually stronger (more affecting) than the thermal component (thermal wind), however the thermal wind is a factor all the way to the tropopause, and will therefore be more significant at high altitude.
When solving questions involving pressures, temperatures and winds, I like to picture the following:
The atmosphere is an accordion (the musical instrument), pulled out so that the folds are parallell to the surface. It rests on a table. Where the pressure is low, that end rests below the table. Where pressure is high, that end of the accordion floats above the table. Where the air is cold, the accordion is slightly compressed, where it is warm, the accordion is pulled out (expanded).
Little marbles are free to roll on the planes that the folds make up, they roll downwards a bit before turning 90 degrees right (northern hemisphere).
So this fellow right here is telling me that:
on the left side of the bottom of the instrument (say Ireland!) the pressure is high (QNH 1020), while on the right side (say England), the pressure is low (QNH 995). The air above Ireland is cold and compact, while that over England is somewhat warmer. The surface wind will go from left to right, add 90 degrees right turn, and you'll know the wind will be northerly. At altitude it will progressively reduce, before becoming southerly way up on the top of the instrument. So the thermal wind is simply the
change between each fold.
Good luck
