NSA/SKYRAD/C2 - Reprocess: IRT insufficiently heated

IRT had insufficient heating to maintain an internal reference temperature above 0 degrees 
C.  Measurements of sky temperature were over-estimated when instrument was below 
freezing.

Data will be reprocessed, but users can correct data using the following correction 
factor:

If T_reference < -5?C, then

  IRT_corrected = (IRT_original - 32.993K)/0.87238

where T_reference can be estimated with the ambient temperature (e.g.
inst_down_long_hemisp_dome_temp or inst_down_long_dome_temp)

• IRT1 minimum(irt1_min)
• IRT1 mean(irt1_mean)
• IRT1 standard deviation(irt1_sd)
• IRT1 maximum(irt1_max)

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