SGP/THWAPS/C1 - RH too high

The T/RH sensor was reporting much higher humidity than the sonde station and nearby 
sensors for some sonde launches.

Use sgpsurthrefC1.b1 or sgpmetC1.b1

• Standard Deviation of Relative Humidity(sd_rh)
• Standard deviation of vapor pressure(sd_vap_pres)
• Vapor Pressure (kiloPascals)(vap_pres)
• Relative Humidity (hybrid-b grid)(rh)