Microclimatological Instrumentation Trent Weather Station (Lafleur) Lethbridge Microclimate Station (Flanagan) Example of Coulee Weather Station (Letts) Tipping Bucket Raingauge Each ‘tip’ is logged by the datalogger Tipping Bucket Raingauge Mechanism Old Fashioned Raingauge Parque Munchique Cauca, Colombia Lakeview Ridge, Waterton Lakes National Park Temperature Measurement Thermocouple •2 wires of different composition joined by an electrical source •Electrical resistance sensitive to temperature •Resistance is measured and coverted to temperature information Thermister •The hotter it gets, the less power it lets through •Resistance is measured and converted to temperature information Temperature and Relative Humidity Temperature and RH sensors housed in Gill Radiation Shield Relative humidity sensor detects vapour adsorption onto a sulfonated polystyrene surface Temperature Sensor: thermister 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 dry bulb thermometers Photo: Trent Weather Station Rainfall and Snowfall Measurements Precipitation Gauge with Nipher Shield Wind Speed and Direction Cup anemometer signal 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 a transmitting to a receiving transducer in both directions determines wind speed and direction Sonic Transducers Why is this sonic anemometer placed so much higher than it would be placed over a grassland or 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 longwave and shortwave energy) Net radiometer Millivolt signals are proportional to the radiation level Pyranometer Measures solar radiation on planar surface Pyrgeometer Measures infrared (longwave) radiation UV-B Radiometer Measures ultraviolet solar radiation on planar surface Base camp 2º30´25´´N, 77º00´02´´W, 1450 m Field Station Tambito al Cocal River Photo taken from microclimate station Juntas, El Tambo, Cauca, Colombia 901 m asl Radiation Measurements L K UV-A K (not visible) L Also: pyranometer for broadband incoming radiation Radiation Data 0 08h00 10h00 12h00 14h00 16h00 14h00 16h00 Solar Time b) Photosynthetically active radiation (µmol m-2 s-1) 1600 1200 800 400 0 08h00 10h00 12h00 Solar Time 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 medium within which it is buried Used for soil energy balance studies Voltage proportional to heat flux through plate Sensible and Latent Heat Fluxes Eddy correlation •Sonic anemometer measurements of vertical velocity and temperature •Krypton hygrometer measurements of water vapour density Krypton Hygrometer Source emits in the 121122 nm range for which absorption by water vapour is strong and other gases do not absorb Detector senses amount of radiation received in this range Baseline established by conventional measurements “Leaf’ Wetness Sensor Leaf Wetness Data 1 0, 9 0, 8 Proportional leaf 0, 7 wetness 0, 6 2.5 m etre s 0, 5 5.0 m etre s 10 m etre s 0, 4 0, 3 0, 2 0, 1 0 0 2 4 6 8 10 12 Hour 14 16 18 20 22 1 0,9 Figure 5.11a Average leaf wetness at 2.5, 5.0 and 10m height within the canopy of the Bosque station. 0,8 Proportional leaf 0,7 wetness 2.5 metres 5.0 metres 10 metres 0,6 0,5 0,4 0,3 0,2 0,1 0 9 Aug 0 19 Aug 200 400 Day 29 Aug 600 7 Sept Downloading data from the datalogger… Ideally, this is how it’s supposed to look… Nice and organized ! Power Supplies Equipment Rack Closed Path IRGAS (CO2/H20 Analyzers) Calibration Equipment Source: Dr. Larry Flanagan Data Acquisition Computer Photosynthesis Measurements Weather stations often support ecological or biological research Other fieldwork related problems… … turned out to be a ‘false’ Coral (phew!)