SGP/SIRS/C1 - SW direct normal data drop out

NIP cable had failed during this time period.

Short_direct_normal data are not recoverable during this time period. However, it can be 
reconstructed using the following formula for each one minute data:
   short_direct_normal = (down_short_hemisp-down_short_diffuse_hemisp)/cos(zenith angle)

• short_direct_normal_std
• short_direct_normal_max
• short_direct_normal_min
• short_direct_normal

• inst_direct_normal