SGP/TWR/C1 - 25m Low battery voltage affected data

Shortly after 2003 GMT on 2 September 1997 a GFCI circuit breaker tripped in the tower 
base AC box, resulting in a drop in CR21X voltage of 0.4 volts in seven minutes.  This 
resulted in a steady drop in battery voltage for the next 30 hours, and incorrect, out of 
range, or missing values for temp, rh, and vap_pres.

• -180.0 - +180.0(alt)
• lon(lon)
• base time in epoch(base_time)
• Vapor Pressure (kiloPascals)(vap_pres)
• Aspirator flow status (% of time with proper flow)(aspirator)
• North Latitude(lat)
• Environmental Temperature (hybrid-b grid)(temp)
• Time offset from base_time(time_offset)
• Relative Humidity (hybrid-b grid)(rh)
• Average battery voltage(vbat)

• Standard Deviation of Air Temperature(sd_temp)
• Relative Humidity (hybrid-b grid)(rh)
• Vapor Pressure (kiloPascals)(vap_pres)
• base time in epoch(base_time)
• lon(lon)
• -180.0 - +180.0(alt)
• Standard deviation of vapor pressure(sd_vap_pres)
• Environmental Temperature (hybrid-b grid)(temp)
• Aspirator flow status (% of time with proper flow)(aspirator)
• North Latitude(lat)
• Standard Deviation of Relative Humidity(sd_rh)
• Time offset from base_time(time_offset)