code  description    
A    Accepted value has passed all QC tests applied as represented by the quality level     
B    Wind speed measurement is less than or equal to 0.1 m per second and wind direction is not considered reliable     
E    Estimated value     
F    Sensor most likely frozen and value is not reliable     
M    Missing value     
Q    Questionable value     
S    Daily value is based on a sunrise to sunrise timeframe     
U    Wind direction is undefined when wind speed measurement is zero