Hubbard Brook Experimental Forest: Vapor Pressure Measurements, 1966 - ongoing

Relative humidity has been measured within the Hubbard Brook Experimental Forest since 1956. Prior to 1981, relative humidity was measured at seven hygrothermographs within the forest. Minimum relative humidity at the time of maximum daily temperature was converted to vapor pressure. Digital data from the hygrothermograph charts are only available for three short periods prior to 1981: January 1966 to April 1966; June 1967 to Sept. 1967 and; May 1971 to April 1973. Beginning in 1981, a humidity sensor has operated as part of the automatic weather station at Headquarters. After installation of the digital sensor in 1981, mean daily air temperature and mean daily relative humidity were used in vapor pressure calculations. These data were gathered at the Hubbard Brook Experimental Forest in Woodstock, NH, which is operated and maintained by the USDA Forest Service, Northern Research Station.