SGP/THWAPS/B4 - RH sensor failure

RH values dropped to ~20% below those recorded at nearby sites and occasionally flatlined 
at 0%.  RH sensor was replaced.

Use nearby MesoNet or SMOS sites RH data instead.

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