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MS001
Meteorological data from benchmark stations at the Andrews Experimental Forest, 1957 to present

PRINCIPAL INVESTIGATOR: Christopher Daly
ORIGINATOR: W. Arthur McKee
OTHER RESEARCHER: Sherri L. Johnson, Mark D Schulze, Christoph K Thomas, Julia A. Jones, Donald L. Henshaw, Fox Sparky Peterson, Adam M Kennedy
DATA SET CONTACT PERSON: Adam M Kennedy, Donald L. Henshaw
ABSTRACTOR: Donald L. Henshaw
METHOD CONTACT: Craig Creel, John Moreau, Greg Downing
FORMER INVESTIGATOR: Richard H. Waring, David Greenland, Mark E. Harmon, Frederick A. Bierlmaier, Michael H. Unsworth, Anne W. Nolin, Adam B. Mazurkiewicz, Alfred B. Levno, Roswell C. Mersereau
METADATA CREATION DATE:
15 Oct 2003
MOST RECENT METADATA REVIEW DATE:
17 Jun 2016
KEYWORDS:
hydrology, meteorology, climatology, climate change, atmospheric pressure, vapor pressure, relative humidity, precipitation, snow accumulation, wind direction, wind speed, snow, air temperature, soil temperature, photosynthetically active radiation, solar radiation, soil moisture, disturbance, monitoring
PURPOSE:
Hydrology, climatology, and biology interact over a wide range of spatial and temporal scales. Continuous interaction among climate, soils, landuse, and vegetation shape the hydrology and ecology of a landscape. Long-term measurements of such variables at various time and space scales provide an essential foundation for understanding ecosystem processes, and document changes in the local, regional, and global environments.
METHODS:
Experimental Design - MS001:
Description:

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.

Citation: The Program for Hydroclimatological Measurement at the H.J. Andrews Experimental Forest by Don Henshaw, Arthur McKee, Alok Sikka 18 Aug 1995 http://andrewsforest.oregonstate.edu/research/component/climate/clim95.pdf
Processing Procedure - MS001: Early PRIMET data:
Description:

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

Field Methods - MS001: Air temperature:
Description:

Please follow this link to see a general description and history of air temperature measurements for these stations:

http://andrewsforest.oregonstate.edu/data/studies/ms01/meta/air.htm

Temperature data has been measured with a variety of instruments:

  • Thermocouple wire: Probe is type T thermocouple soldered from thermocouple wire
  • Campbell Scientific thermistor probe: Campbell Scientific model 107 temperature probe (CS107B, CS107B-L) includes the Fenwal Electronics UUT51J1 thermistor
  • Vaisala Relative Humidity/Temperature probes: Temperature and relative humidity are sampled by a Campbell Model HMP35C or the HMP45C probe containing a Vaisala capacitive relative humidity sensor and a Fenwal Electronics UUT51J1 thermistor

Probes were housed in locally designed PVC radiation shields from the 1980s until the mid 2000s. Gill radiation shields replaced the PVC shields at all of the benchmark sites after a significant concurrent comparison was made. Aspirated shields are also now in use. The original 1.5 meter Primary Met Station sensor was housed in a Cotton Region Shelter. Historical methods included Rustrak strip charts with thermister where air temperature is measured by a Yellow Springs Instruments linear thermistor in a standard Cotton Region Shelter and continuously recorded on a separate 30-day Rustrak strip chart scaled from -10 degrees C to 40 degrees C.

Data loggers are typically Campbell Scientific (CR10, CR21X, CR500, or CR23X). Early data loggers used in the 1980s are Interface Instrument models M-2, M-3, and M-4.

Instrumentation: Thermocouple wire; Campbell Scientific model 107 temperature probe (CS107B, CS107B-L) includes the Fenwal Electronics UUT51J1 thermistor; Campbell Model HMP35C or the HMP45C probe containing a Vaisala capacitive relative humidity sensor and a Fenwal Electronics UUT51J1 thermistor; Campbell Scientific data loggers (CR10, CR21X, CR500, or CR23X); Interface Instrument models M-2, M-3, and M-4
Field Methods - MS001: Dew point temperature:
Description:

Please follow this link to see a general description and history of dew point temperature measurements for these stations:

http://andrewsforest.oregonstate.edu/data/studies/ms01/meta/dew.htm

Dew Point is calculated from air temperature and relative humidity every sampling interval (generally every 15 seconds) and output hourly using Tetens Equation for the relation between temperature and the partial pressure of water vapor (see http://andrewsforest.oregonstate.edu/data/studies/ms01/dewpt_vpd_calculations.pdf). This is calculated for independent pairs of air temperature and relative humidity probes at 150 and 450 cm heights for all benchmark stations (except CS2MET which only has sensors at 150 cm height).

Historical methods at PRIMET used a heated lithium-chloride dew point sensor with a thermistor that recorded continuously on a separate 30-day Rustrak strip chart throughout the 1970s. An Interface Instrument hygrometer with linear thermister was used to measure dew point indirectly with a heated Interface Instrument lithium-chloride hygrometer with a linear thermistor from 1979 until 1988. The PRIMET early dew point sensors and subsequent air temperature and relative humidity sensors used to calculate dew point were located in the 150 cm height cotton shelter until May 2000. The cotton shelter was discontinued for dew point calculation and replaced with use of the 450 cm probe on the PRIMET tower.

Instrumentation: Early instrumentation at PRIMET in the 1970s included a heated lithium-chloride dew point sensor. The sensor temperature is measured with a thermistor and recorded continuously on a separate 30-day Rustrak strip chart scaled from -5 degrees C to 20 degrees C with and with an accuracy and resolution of 1 degree C. The Interface Instrument M-2 or M-3 data logger was used. This sensor was often very unreliable. In the 1980s, dew point temperature is measured indirectly by a heated Interface Instrument lithium-chloride hygrometer with a linear thermistor. The accuracy is +/-0.5 degrees C with a resolution of 0.1 degrees C, and range of -14 to 29 degrees C. The Interface Instruments M-4 data logger was used. All other dew point measurements have been calculated from air temperature and relative humidity sensors.
Field Methods - MS001: Precipitation:
Description:

Please follow this link to see a general description and history of precipitation measurements for these stations:

http://andrewsforest.oregonstate.edu/data/studies/ms01/meta/ppt.htm

Precipitation records are generally evaluated every 5 minutes and data points are output to capture 5 minute resolution. In actuality, not all of the gauges are designed for accurate recording at this high temporal frequency except during periods of high intensity rain/snowfall. This is generally due to the sensitivity of the magnetostrictive tank gauge and associated tank diameter in measuring fluid level. The "stand-alone" gauges at UPLMET, VANMET and CENMET are designed for greater sensitivity to changes in tank depth and the 5 minute output is good during most precipitation events. The "shelter gauges" at those sites are not as sensitive to a change in fluid depth. The tipping bucket gauge at PRIMET reliably outputs tips on a 5 minute basis, although this record is somewhat artificial at 5 minute resolution, especially in light rain situations where the gage does not tip in every 5 minute segment and 15 minute resolution is probably more realistic. Early chart data at CS2MET and the H15MET have been digitized and are generally accurate at 15 minutes resolution.

The longest continuous precipitation record on the Andrews is at the Climatic Station on Watershed 2 (CS2MET): 1957-10-01 to Present. Data is collected weekly from a standard US Weather Bureau standard 8” rain gauge and an adjacent Universal recording gauge (chart). The weekly charts were originally hand digitized on a daily basis, and adjusted to the standard gauge total. Subsequently, all charts have been electronically digitized, and data can be reliably output at a 15 minute resolution. This high resolution chart data has also been corrected to the standard gage total on a weekly basis. This Universal rain gauge was originally positioned at another location on the Andrews (at FORKS) and that record can be used to extend the daily CS2MET precipitation record back to December, 1951. A ETI Instruments NOAH IV gauge was installed in 2011 and runs concurrently with the Universal gauge and the standard gauge

At the Hi-15 Meteorological Station (H15MET), a standard rain gauge has always been maintained along with an accompanying recording rain gauge. Historically, the charts were hand digitized on a daily basis, and the daily record corrected to the standard gauge periodic total using a prorating technique. Beginning in 1992 a more reliable recording gauge was installed using a pressure transducer to measure fluid depth, and this record is available with no correction to the standard gauge, although the standard gauge is still operational.

At both the Upper Lookout (UPLMET) and Central (CENMET) Stations, two gauges are in operation: a stand-alone gauge with two concentric, encircling wind fences, and a second gauge atop the station shelter. The orifice of the stand alone gauge is heated by a thermistatically-controlled propane heater. This heated gauge with the shielding fences has dramatically improved our precipitation catch, particularly in heavy snow conditions, and has prevented snow bridging over the gauge orifice. The shelter gauge is located on top of our station shelter and heated through ducts from the shelter's propane heating system. This gauge has also improved catch over the more traditionally heated rain gauges, but is protected only with an alter wind shield and catches less than the stand-alone.

At Vanilla Leaf (VANMET) the original gauge in the clearcut was installed in 1987 but the record is discontinued in 1996. This gauge suffered from its openly exposed siting in this high elevation clearcut. Heavy snow and inadequate wind shielding were major problems. A stand-alone type gauge similar in design to those used at UPLMET and CENMET was installed in the adjacent and naturally sheltered meadow above the VANMET clearcut in 1998. This site takes advantage of the naturally-protected meadow and the wind fences are not employed here.

Instrumentation: Stand-alone rain gauges with Valdais-type concentric wind fencing are designed for use at remote Andrews locations in heavy snow conditions. The stand-alone gauges are constructed in two sections: 1) a heated orifice section 2) an unheated stand pipe section, and are designed to work with Campbell Scientific data loggers. The two concentric, encircling wind fences are used at CENMET and UPLMET (see design description http://andrewsforest.oregonstate.edu/data/studies/ms01/stand_alone_raingage_design.pdf). Shelter-top rain gauges are currently in use at CENMET, UPLMET, and H15MET. The shelter-top gauge sits on top of a shelter and is heated using ducted shelter heat from the shelter propane heater controlled by the datalogger and thermistor. Continuous precipitation is measured by recorded tank depth measurements (magnetostrictve tank gauges or pressure transducer) in association with Campbell Scientific data loggers. Stevens A-35 chart recorders were used at some sites as a precipitation record backup. Wind Alter shields are typically employed. The Climatic Station at WS#2 (CS2MET) employs a Belfort Universal Recording Rain Gage, Cat No. 5-780 Series. 8" diameter, 12" capacity, and accuracy of .33%. The record is corrected to a nearby 8" US Weather Service Standard Raingage. An ETI Instruments Noah IV gauge was installed in 2011. The Primary Met Station employs a Texas Electronics tipping bucket gauge with 8" diameter orifice with data logger located on a 1 meter high platform with a Campbell Scientific data logger.
Field Methods - MS001: Relative humidity:
Description:

Please follow this link to see a general description and history of relative humidity measurements for these stations:

http://andrewsforest.oregonstate.edu/data/studies/ms01/meta/rel.htm

Generally, relative humidity is output hourly and is measured at heights of both 150 and 450 cm at these benchmark stations using Vaisala sensors with Campbell data loggers. Early records at CS2MET employed a hygrothermograph sensor to record daily max-min relative humidity from within a Cotton Region shelter on a recording chart from 1958 to 1998. Standard maximum and minimum thermometers on a Townsend support and a sling psychrometer were used to make weekly corrections to the hygrothermograph chart readings.

Instrumentation: Temperature and relative humidity are sampled by Campbell Model HMP35C or HMP45C probes containing a Vaisala capacitive relative humidity sensor and a Fenwal Electronics UUT51J1 thermistor. The probes were originally housed in a locally-designed PVC radiation shield, which were later replaced with Gill radiation shields. Campbell Scientific data loggers are used. The original 1.5 meter Primary Met Station sensor was housed in a Cotton Region Shelter. Historical instrumentation include the the Weather Measure Hi-Q hygrothermograph (http://www.novalynx.com/225-5020.html), a precision, self-contained recording instrument that measures and records ambient temperature and relative humidity simultaneously on a double scale chart. A specially treated bundle of human hair is used to measure relative humidity over the full range of 0 to 100%. The hair expands and contracts with increasing or decreasing amounts of water vapor in the air. The chart is installed on a self-contained brass clock which is spring-wound with accuracy of +/- 1%. A Belfort hygrothermograph had been used previously in the late 1950s and 1960s. The Belfort Maximum Minimum Thermometer Cat No. 5-484 indicates the temperature extremes reached over a 24 hour period and is the standard for correcting chart temperature readings.
Field Methods - MS001: Snow lysimeter:
Description:

Please follow this link to see a general description and history of snow lysimeter measurements for these stations:

http://andrewsforest.oregonstate.edu/data/studies/ms01/meta/lys.htm

Precipitation and melting snow runoff are measured by a tipping bucket with tips summarized in 5 minute intervals. General installation: The lysmeter collection pan was constructed from 2 x 12s and plywood. The pan was covered with hyplon (white vinyl polymer), and a bathtub drain installed in one corner. The pan was installed on the ground surface and was leveled such that the collected water would flow to the corner with the drain. The water is then directed to a tipping bucket (TB) in the basement of the structure by pvc pipe which is buried to prevent freezing. The final deminsions of the lysimeter pan are 92" x 93" x 12", so a volume of water equal to .01" of ppt is 1.4032 L.

Instrumentation: The Campbell data logger records the Tipping Bucket snow lysimeter tips (.01" of ppt/snowmelt input). An electromagnetic counter acts as a check to recorded tips. Sensors are connected to the data logger through a Campbell wiring panel.
Field Methods - MS001: Snow moisture and depth:
Description:

Please follow this link to see a general description and history of snow water equivalence (moisture) and snow depth measurements for these stations:

http://andrewsforest.oregonstate.edu/data/studies/ms01/meta/sno.htm

Snow water equivalence (SWE) and snow depth are measured every 5 minutes. Due to high variability in readings, particularly of snow depth, values may only be posted every hour for some data. Snow moisture is measured with a Park Mechanical pressure pillow and Druck pressure transducer. Snow depth is measured with a Campbell Scientific model SR50 sonic ranging snow depth sensor or Judd communications snow depth sensor. The snow depth sensor takes up to 10 readings, performs error checking and outputs a reading in mm every 5 minutes. Depth sensor measurement range is 0.5 to 10 meters. The snow sensor is mounted on a long pipe extending from the shelter. The snow pillow readings are instantaneous at 5 minute intervals. Campbell Scientific data logger is used. Snow moisture and snow depth are merged in the output files.

Instrumentation: Snow moisture is measured with a Park Mechanical pressure pillow and Druck pressure trandsducer. Snow depth is measured with a Campbell Scientific model SR50 sonic ranging snow depth sensor or Judd communications snow depth sensor. Campbell Scientific data loggers are used.
Field Methods - MS001: Snow course :
Description:

Snow moisture and snow depth are measured with snow cores at 5 points across a transect (see entity 20). This station snow course (transect) is near the station and tries to follow a single contour. The average of these 5 points provides a check of the snow pillow and snow depth sensor. Snow depth is also measured at each corner of the station snow pillow using a permanently set graduated stake (pvc pipe). The average depth is converted to snow water equivalence using the density calculated from the station snow course.

Instrumentation: Mt Rose snow core sampler
Field Methods - MS001: Soil moisture:
Description:

Please follow this link to see a general description and history of soil moisture measurements for these stations:

http://andrewsforest.oregonstate.edu/data/studies/ms01/meta/smo.htm

Soil moisture is measured with a water content reflectometer (WCR) beginning in 1998 replacing older gypsum block technology. Values are output on a daily basis at four depths (10, 20, 50, 100 cm) from the four benchmark stations (PRIMET, CENMET, UPLMET, VANMET)

Instrumentation: Campbell Scientific CS615 Water Content Reflectometers
Field Methods - MS001: Soil moisture potential:
Description:

Please follow this link to see a general description and history of soil moisture potential measurements for these stations:

http://andrewsforest.oregonstate.edu/data/studies/ms01/meta/smp.htm

Gypsum blocks were used to record mean daily soil moisture potential at the four benchmark stations (PRIMET, CENMET, UPLMET, VANMET) beginning in 1994. Water content reflectometers were added beginning in 1998 at all sites and all gypsum block measurements were terminated by May 2000. Hourly measurements were made between 1988 and 1990 at PRIMET but were discontinued and restarted in Oct 1994 on a daily basis only. At VANMET, soil moisture potential measurements were summarized by daytime and nighttime hours only from 1987 to 1994 at depths of 10, 20, 30 cm. From 1987 to 1993, mean daily soil moisture potentials were recorded in the rooting zone of 3 individual trees at VANMET.

Instrumentation: Campbell Scientific model 223 gypsum soil moisture blocks were used historically. A polynomial equation relates changes in soil moisture with changes in block resistance. The manufacturer supplied equation is calibrated from -.1 to -15 bars. Values less than -15 bars are listed as out of range. Data logger is Campbell Scientific.
Field Methods - MS001: Soil temperature:
Description:

Please follow this link to see a general description and history of soil temperature measurements for these stations:

http://andrewsforest.oregonstate.edu/data/studies/ms01/meta/soi.htm

Mean hourly soil temperatures are measured at the four benchmark stations (PRIMET, CENMET, UPLMET, VANMET) at four depths (10, 20, 50, 100 cm). Thermocouple wire was used in the earliest measurements and were protected inside of a PVC structure. Most measurements begin in 1994 but measurements were made at PRIMET beginning in 1988 at 20 cm depth only. At VANMET, measurements were summarized by daytime and nighttime hours only from 1987 to 1993 at depths of 10, 20, 30 cm, and soil temperature was recorded in the rooting zone of 3 individual trees.

Instrumentation: Thermocouple wire: Probe is type T thermocouple soldered from thermocouple wire or, Campbell Scientific thermistor probe: Campbell Scientific model 107 temperature probe (CS107B, CS107B-L) includes the Fenwal Electronics UUT51J1 thermistor. Data logger is a Campbell Scientific, typically CR10, CR21X, CR500, or CR23X.
Field Methods - MS001: Solar PAR:
Description:

Please follow this link to see a general description and history of photosynthetically active radiation (PAR) measurements for these stations:

http://andrewsforest.oregonstate.edu/data/studies/ms01/meta/par.htm

Mean Photosynthetically active radiation (PAR) is measured at Central Meteorological Station (CENMET) and output at 15 minute intervals. Maximum solar radiation is based on instantaneous micromoles per second per square meter, and the time of the maximum value is accurate to the minute. It is common for solar radiation sensors to read negative at night (-1 to -7), and negative nighttime readings are changed to 0. The daily values average in these negative values, creating a minor error in the daily values.

Instrumentation: LICOR PAR (photosynthetically active radiation) quantum sensor, Campbell Scientific model LI190SB. The output of the PAR sensor is a daily average, daily maximum and 15 minute averages, and the units are in micromoles/sec/meter2.
Field Methods - MS001: Solar radiation:
Description:

Please follow this link to see a general description and history of solar radiation measurements for these stations:

http://andrewsforest.oregonstate.edu/data/studies/ms01/meta/sol.htm

Total incoming solar radiation is recorded at the four benchmark stations (PRIMET, CENMET, UPLMET, VANMET) and output every 15 minutes starting in 1994. This total incoming solar radiation data is also output every day in megaJoule per m2 along with the maximum daily rate of incoming solar radiation in watts per m2 and the time of the maximum accurate to the minute. Solar radiation measurement began in 1972 at PRIMET, but much of the incoming solar radiation data from the 1970's is estimated. Values are output on an hourly basis until 1994 at PRIMET. Data had originally been output as langleys but has been converted to more standard units.

Instrumentation: Kipp and Zonnen solar radiation pyranometer with thermopile type sensor, model CM-6B with Campbell Scientific data logger located on a 1 meter high platform at Primary Met and on top of shelters at other stations. An earlier model used was the CM-5 with an Instrument Interface M4 data logger. Historical method: The signal is recorded continuously from the Lintronic dome solarimeter on a 30-day Rustrak strip chart scaled from 0 to 2.0 cal/cm2/min with a resolution of 0.1 cal/cm2/min. Data loggers used were the Interface Instrument M-2 or M-3. This historical solar sensor was often unreliable.
Field Methods - MS001: Watervapor pressure deficit:
Description:

Please follow this link to see a general description and history of water vapor pressure deficit measurements for these stations:

http://andrewsforest.oregonstate.edu/data/studies/ms01/meta/vpd.htm

Vapor pressure deficit values are calculated and output hourly from air temperature and relative humidity probes that sample every 15 seconds. Values are output in millibars and are collected at 150 and 450 cm heights at each of the four benchmark stations (PRIMET, CENMET, UPLMET, VANMET). The earliest hourly calculations were started at PRIMET in 1988 from air temperature and relative humidity sensors located in the 150 cm cotton shelter based on sampling every 15 seconds (in millibars). Please see the following for calculation details: http://andrewsforest.oregonstate.edu/data/studies/ms01/dewpt_vpd_calculations.pdf

Instrumentation: Water vapor pressure deficit is computed from relative humidity and air temperature every 15 second sampling interval and output hourly.
Field Methods - MS001: Wind speed and direction:
Description:

Please follow this link to see a general description and history of precipitation measurements for these stations:

http://andrewsforest.oregonstate.edu/data/studies/ms01/meta/wnd.htm

Hourly mean wind speed, resultant mean wind vector magnitude and standard deviation, resultant mean daily wind vector direction, and daily wind direction vector components (Wind Rose) are output at each of the four benchmark stations (PRIMET, CENMET, UPLMET, VANMET). The data logger samples every 15 seconds and the sensor is installed a 10m height. It has been discovered that wind speed from this propeller-style wind anemometers are not accurate below 1 meter per second. Much of this data will be tagged as 'Questionable' or possibly removed.

Instrumentation: Wind speed and direction is sampled by a RM Young Model 05103 Wind Monitor mounted to the tower. Potentiometer measures direction, anemometer measures wind speed. Data logger is a Campbell Scientific model. Data collected by the Wind Monitor is processed by the Campbell Wind Vector instruction #69 option #2. Historical method: Wind speed was measured with a cup-type anemometer which provides contact closure for every .322 km of air movement. This signal is recorded by an event marker along the border of the same Rustrak strip chart used to record dewpoint. Data logger is Interface Instrument M-2 (1970's) or, Wind speed sensors (R.M. Young #6101 tachometer generators) were mounted on a tower. Data logger is Interface Instrument M-4 (1980's).
Models/Algorithms - MS001:
Description:

Dewpoint and vapor pressure deficit equations can be found at:

http://andrewsforest.oregonstate.edu/data/studies/ms01/dewpt_vpd_calculations.pdf

SUPPLEMENTAL INFORMATION:
NSF grants: DEB-7611978, DEB-8012162, DEB-8514325, DEB-9011663, DEB-9632921, DEB-0218088, DEB-0823380, DEB-1440409
SITE DESCRIPTION:
Temperature and rainfall in the Andrews Experimental Forest are are typical of a maritime climate with wet, relatively mild winters and dry, cool summers. Humidity is generally high through winter months, and maximum daily relative humidity approaches 100 percent at night throughout the year. Minimum summer humidities generally hover around 30-50 percent. Temperature extremes range from near 0 degrees F in unusually cold winters to over 100 degrees for brief periods almost every summer. The range in mean annual temperature (1972-2002) is 7.1-10.5 degrees C at a low elevation site (PRIMET). Precipitation varies with elevation - long-term annual average at low elevation (450 m) is 2200 mm, and at high elevation (1200m) is 2600 mm.
TAXONOMIC SYSTEM:
None
GEOGRAPHIC EXTENT:
H. J. Andrews Experimental Forest
ELEVATION_MINIMUM (meters):
436
ELEVATION_MAXIMUM (meters):
1300
MEASUREMENT FREQUENCY:
continuous
PROGRESS DESCRIPTION:
Active
UPDATE FREQUENCY DESCRIPTION:
annually
CURRENTNESS REFERENCE:
Ground condition