Interesting topic.
As noted by others, Winds from the tower are based on a 10m height above the ground, at one location at the airport. The AWOS winds are based on a 2 minute average, including gusts on a 10 minute average.
ATIS winds are updated every 10 minutes, using the same equipment, this is why one must use the tower reported winds for landing.
FMS winds are calculated using the pitot tubes (at least one set front/back) and the distance the INS says it has travelled. Winds are only 2d horizontal headwind and tailwind, as the system can only measure winds in the direction of travel. Depending on the system, the winds are updated every 4 to 5 seconds. Due to latency, it tells you the winds where you were...
When an aircraft is descending, the measurement being only 2D horizontal headwind or tailwind, doesnt really accurately represent the wind because of the 3D vertical component of descent.
Other issues such as turns, once again, winds may not be accurately represented.
Many FMS use a 'blended' wind calculation. The FMS allows for wind input, but only at 3 or 4 locations. There were the forecasted winds in the system from flight ops at departure, the real time winds, and the input winds. Some systems will only update if the winds are outside parameters set from the forecast.
Winds input will be updated on the specific location or waypoint only, but may be blended as an average.
Many of these issues are coming up as a result of the trajectory and time based flow management programs being researched.
Is there a scripted mandatory go-around based on FMC wind only? No.
I wonder about this. Airbus has the automated wind shear alert system, that senses winds, looking for the probability of wind shear. From what I understand, if this system alerts, it is a mandatory GA. I am not certain of the parameters, but from what I understood, it does look at headwind/tailwind, and horizontal/vertical displacement.
Perhaps A drivers can add something about this.
There are also systems that send an ACARS message with data like this for flightdeck use...
Does anyone use this type of information?