Hubbard Brook Experimental Forest (USDA Forest Service): Vapor Pressure Measurements, 1966 - present

Hygrothermographs have collected relative humidity at 7
locations within the Hubbard Brook Experimental Forest since
1956. Minimum relative humidity at the time of maximum daily
temperature is then converted to vapor pressure. Because
vapor pressure varies little throughout a day and among
locations, data from all available hygrothermographs were
averaged in order to reduce error. Most of the period of
record prior to 1981 is not digitally available. Data have
only been read from the hygrothermograph charts for three
periods: January 1966 to April 1966; June 1967 to Sept. 1967
and; May 1971 to April 1973. However, the entire
hygrothermograph chart collection has recently been scanned
and prepared for data extraction to fill in gaps in the
dataset. Beginning in 1981, a humidity sensor has operated as
part of the automatic weather station at Headquarters. These data were gathered as part of the Hubbard Brook
Ecosystem Study (HBES). The HBES is a collaborative effort at
the Hubbard Brook Experimental Forest, which is operated and
maintained by the USDA Forest Service, Northern Research
Station.