NSA/METTWR/C1 - 2m Wind Direction Sensor Freezing

The 2m wind direction was failing.  It began to exhibit instances of no movement 
suggesting it was frozen.  After some time it began to make erratic measurements compared to the 
co-located Ultrasonic and compared to the directions at the other levels.

Use the ultrasonic wind direction data.

• 2m Vector Averaged Wind Direction(WD2M_DU_WVT)
• Standard Deviation of 2m Vector Averaged Wind Direction(WD2M_SDU_WVT)