Much of the early climatological measurements on the Andrews Forest were associated with the investigation of the initial small watersheds experiment (Watersheds 1, 2, 3). The Climatic Station on WS 2 was installed in 1956 to measure precipitation and a hygrothermograph was added in 1958. The High-15 station was established to measure precipitation in 1964 in conjunction with small watersheds 6, 7, 8, and has evolved into a secondary meteorological station. A more general set of modeling needs led to the installation of the Primary Meteorological Station in 1972 to characterize the meso-scale environment. Originally, solar radiation, air temperature, dew point temperature, and windspeed were collected. Along with precipitation from the climatic station on WS 2, these were the primary climatic variables needed for the models predicting the rates at which materials accumulate or move through ecosystems (Waring et al., 1978). Significant improvements to the station were made in 1975, 1979, and 1988, as the station evolved from chart recorders to state-of-the-art digital data loggers (Bierlmaier and McKee, 1989). The Vanilla Leaf Met Station was installed in 1987. The primary intent was to provide micro- meteorological data for a study of seedling survival following clearcut and shelterwood logging at high elevation. Ultimately, the shelterwood site was discontinued and the clearcut site has evolved as a primary high elevation meteorological station.
Four Benchmark Meteorological Stations (BMS) and two second-level stations are included in the MS001 database. The Primary Meteorological and Vanilla Leaf Meteorological BMS are retained. Two new BMS are installed. In 1994, the Upper Lookout Meteorological Station was established at high elevation (4200 ft, ENE aspect) on clearcut L708 in the SE Andrews. In 1995 the Central Meteorological BMS was established at a centrally located site on clearcut L351 (3300 ft, WSW aspect) in the east-central Andrews. A GIS analysis of elevation and aspect indicated the average elevation (3170 ft., 966 m) and average aspect (267 degrees) of the Andrews Forest, and the Central Met Station was located to represent these general averages. Modifications are made to the Primary and Vanilla Leaf Stations to standardize measured variables, temporal resolution, methods, and instrumention across all BMS. Sites will be cleared and required openings maintained following standards of the National Weather Service, the LTER network, and where appropriate, the NADP network. Telemetering of all BMS was completed in 1996. Second-level stations (SLS) at the Hi-15 and WS 2 Climatic Station will continue to be maintained for measurement of precipitation, temperature, and other data to maintain continuity of historical records. These sites also follow established procedural standards.
The BMS include meteorological measurement of air and soil temperature, relative humidity, calculated dew point temperature and vapor pressure deficit, wind speed and direction measurement, incoming solar radiation, photosynthetically active radiation (PAR), soil moisture, snow melt, and snow moisture and depth.
View the climate data collection methods used over time at select stations by following the link below. You can filter results by parameter, climate station, and date range, or use the general text search.
https://hjandrews.shinyapps.io/im_methods_history/
Radiation measurements are collected at multiple stations:
PRIMET and VANMET (benchmark stations): NR01 4-component sensors record mean downward and upward shortwave and longwave radiation, plus total net radiation. Data output every 5 minutes starting in 2013.
Daily mean values for all radiation components are post-calculated and reported in watts per m2.
View climate data collection methods used by each unique probe by following the links below. Filter results by database code, site code, parameter, probe, climate station, and date range. A general text search is also available.
https://andlter.forestry.oregonstate.edu/MethodCode/View_History.aspx
Photosynthetically Active Radiation (PAR) measurements:
Mean PAR is measured at Central Meteorological Station (CENMET). Output schedule: 5-minute intervals starting April 2015; prior to that, 15-minute intervals starting in 1998.
Maximum solar radiation is based on instantaneous measurements in micromoles per second per square meter. The time of maximum value is accurate to the minute.
Data quality note: Solar radiation sensors commonly read slightly negative at night (-1 to -7 µmol/s/m2). Negative nighttime readings are changed to 0 in the dataset. Because daily averages include these negative values before correction, a minor error exists in the daily values.
View climate data collection methods used over time at select stations by following the link below. Filter results by parameter, climate station, date range, database code, site code, and probe. A general text search is also available.
Solar radiation measurements:
Benchmark stations (PRIMET, CENMET, UPLMET, VANMET): Total incoming solar radiation calculated with 5-minute output starting in 2014 or 2015 (depending on site). Prior to that, 15-minute output starting in 1994.
WS7MET (secondary benchmark site): Pyranometers record mean downward and upward shortwave radiation. Output schedule: 10-minute intervals beginning February 16, 2007; changed to 15 minutes on September 24, 2012; changed to 5 minutes on April 30, 2015. These two pyranometers were removed on September 9, 2022 and replaced with a single upward facing pyranometer (CS320)
PRIMET and VANMET: NR01 net radiometers installed in 2013 to record upward and downward shortwave radiation components.
Data format and units:
Method codes in the dataset differentiate between total incoming and outgoing solar radiation measurements.
Pre-2015 data was output daily in megajoules per m2, along with maximum daily rate of incoming solar radiation (watts per m2) and time of maximum (accurate to the minute). Since 2015, daily mean downward and upward shortwave radiation data are post-calculated and reported in watts per m2.
Historical notes:
Solar radiation measurement at PRIMET began in 1972 with hourly output until 1994. Much of the incoming solar radiation data from the 1970s is estimated. Original data output in langleys has been converted to standard units.
View climate data collection methods used over time at select stations by following the link below. Filter results by parameter, climate station, date range, database code, sitecode, and probe. A general text search is also available.
Longwave radiation measurements:
NR01 net radiometers were installed at PRIMET and VANMET benchmark stations in 2013, recording mean upward and downward longwave radiation components. Total longwave radiation measurements began in 2018.
Method codes in the dataset differentiate between mean and total values for incoming and outgoing solar radiation. Since 2015, daily mean downward and upward longwave radiation data are post-calculated and reported in watts per m2.
A description of the early processing history and instrumentation for the Primary Meteorological Station (PRIMET), 1972-1989, is posted here:
http://andrewsforest.oregonstate.edu/data/studies/ms01/ms001_primet_1972_1989.pdf
