SGP/THWAPS/B6  - Minor biases in humidity and saturation vapor pressure

The THWAPS humidity sensor output was scaled so that the instrument output
voltage range (0-1VDC) represented 0-100 %RH. Comparisons with the
co-located chilled mirror sensor at the CF suggested that the THWAPS RH
sensor was reading artifically low at high humidities because of this 100
%RH maximum. 
   
The scaling of the system was changed so that 0-1 VDC now represents 0-110
%RH. This resulted in a slight loss of precision in the measurements, but
since the RH measurement is only accurate to 2-3 %RH at best, this isn't a
significant problem.
   
The saturation vapor correction when temps are below 0C contained an error
in the multiplier.  The incorrect multiplier only equates to an error of
0.01 kPa which is less than the stated uncertainty of the measurement (+/-
0.035 kPa).

• Vapor Pressure (kiloPascals)(vap_pres)
• Relative humidity scaled, by total column amount from MWR(rh)