NSA/SKYRAD/C1 - Downwelling IRT bias

The downwelling IRT was measuring higher sky/cloud temperatures than the AERI. The problem 
was corrected when the mirror was replaced.

• Sky Infra-Red Temperature(sky_ir_temp)
• Sky Infra Red Temperature Maxima(sky_ir_temp_max)
• Sky infrared temperature, standard deviation(sky_ir_temp_std)
• Sky Infra-Red Temperature Minima(sky_ir_temp_min)