NSA/SKYRAD/C2 - Instrument grounding problem

The down_long_hemisp1 was often 50 W/m^2 greater than down_long_hemisp2 during the suspect 
times.  Data logger grounding issues were addressed by site ops and have corrected the 
problem.

Use down_long_hemisp2.

• Instantaneous Downwelling Pyrgeometer Case Thermistor Resistance, Pyrgeometer1(inst_down_long_hemisp1_case_resist)
• Instantaneous Downwelling Pyrgeometer Thermopile, Pyrgeometer1(inst_down_long_hemisp1_tp)
• Instantaneous Downwelling Pyrgeometer Dome Thermistor Resistance, Pyrgeometer1(inst_down_long_hemisp1_dome_resist)

• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer1, Maxima(down_long_hemisp1_max)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer1, Standard Deviation(down_long_hemisp1_std)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer1, Minima(down_long_hemisp1_min)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer1(down_long_hemisp1)