Microclimatological Instrumentation

Lethbridge Microclimate Station (Flanagan)

Trent Weather Station (Lafleur)

Temperature Measurement

Thermocouple

2 wires of different composiotion joined by an electrical sourceElectrical resistance sensitive to temperatureResistance is measured and coverted to temperature information

Thermister

The hotter it gets, the less power it lets throughResistance is measured and converted to temperature information

Temperature and Relative Humidity

Temperature and RH sensors housed in Gill Radiation Shield

Relative humidity sensordetects vapour adsorption onto a sulfonated polystyrene surface

Temperature Sensorthermister

                        

Function of Shields:Protect sensor from radiation (especially incoming shortwave and outgoing longwave radiation) while allowing air to pass.

Stevenson Shield

An earlier radiation shield often used with wet and drybulb thermometers

Photo: Trent Weather Station

Rainfall and Snowfall Measurements

Precipitation Gauge with Nipher Shield

Wind Speed and Direction

Cup anemometersignal frequency converted to windspeed

Wind vane

Sonic anemometer

Sound waves measure wind speed and temperature

Time of flight for a sonic impulse to travel from atransmitting to a receiving transducer in both directions determines wind speedand direction

SonicTransducers

Why is thissonic anemometerplaced so much higher than it would be placedover a grasslandor a peatland ?

Source: University of Colorado(African savanna site)

Micrometeorological Tower

Yikes !

Radiation Measurements

Shields made of materials appropriate for desired wavelength(eg. polyethylene for net radiation – transparent to both longwaveand shortwave energy)

Millivolt signals areproportional to the radiation level

Net radiometer

PyranometerMeasures solar radiation onplanar surface

PyrgeometerMeasures infrared (longwave)radiation

UV-B RadiometerMeasures ultraviolet solar radiationon planar surface

Field Station

Tambito al Cocal River

Base camp2º30´25´´N, 77º00´02´´W, 1450 m

Photo taken from microclimate station

Juntas,El Tambo,Cauca,Colombia

901 m asl

Radiation Measurements

Also: pyranometer for broadband incoming radiation

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L K

K (not visible)

UV-A

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TMC F ( Dry)

TMC F (We t )

Max (TMCF Dry)

Max (TMCF We t )

Figure 5.1b. Solar radiation during the dry season and wet season (November) atCentro de Estudios Ambientales Tambito.

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Solar radiation(W∙m-1)

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TMCF (Dry )

TMCF (We t )

Max (TMCF We t )

Ma x (TMCF Dry )

Figure 5.6a Ultraviolet A radiation at Napo, and during the dry season (August) at Centro de Estudios Ambientales Tambito.

Figure 5.6b Ultraviolet A radiation during the dry season and wet season (November) at Centro de Estudios Ambientales Tambito.

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Ultraviolet-A(W∙m-2)

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Ultraviolet-A(W∙m-2)

Radiation Data

More radiation sensors…

Source: University of Colorado

Diffuse Radiation

Measured using a shade disk

Radiation from entire sky except from within 3 of Sun

Heat Flux Plate

Senses conductive heat transmission in the mediumwithin which it is buried

Used for soil energy balance studies

Voltage proportional to heat flux throughplate

Sensible and Latent Heat Fluxes

Eddy correlation (later)

•Sonic anemometer measurements of vertical velocity and temperature

•Krypton hygrometer measurements of water vapour density

Krypton Hygrometer

Source emits in the 121-122 nm range for which absorption by water vapour is strong and other gases do not absorb

Detector senses amount of radiation received inthis range

Baseline established by conventional measurements

                                                 

Old Fashioned Raingauge

Parque MunchiqueCauca, Colombia

Tipping Bucket Raingauge

Each ‘tip’ is logged bythe datalogger

“Leaf’ Wetness Sensor

Figure 5.11a Average leaf wetness at 2.5, 5.0 and 10m height within the canopy of the Bosque station.

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Proportional leaf wetness

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Figure 5.11b Complex pattern of leaf wetness at 2.5, 5.0 and 10m height within the canopy of the Bosque station.from August 9 to September 9, 1999.

9 Aug 19 Aug 29 Aug 7 Sept

Proportional leaf wetness

Day

Leaf Wetness Data

Downloading data from the datalogger…

Ideally, this is how it’s supposed to look…

Power Supplies

Closed Path IRGAS

Data Acquisition Computer

CalibrationEquipment

Equipment Rack

(later)

Source: Dr. Larry Flanagan

Nice and organized !

Other fieldwork related problems…

… turned out to be a ‘false’ Coral (phew!)

Still to come:•CO2/H2O AnalyzerMeasures CO2 and H2O fluxes using eddy covariance techniques

Why ? To measure carbon balance