title: PARduino: a simple and inexpensive device for logging photosynthetically active radiation.
abstract: Photosynthetically active radiation (PAR, 400-700 nm) is one of the primary controls of forest carbon and water relations. In complex terrain, PAR has high spatial variability. Given the high cost of commercial datalogging equipment, spatially distributed measurements of PAR have been typically modeled using geographic coordinates and terrain indices. Here, we present a design for a low-cost, field-deployable device for measuring and recording PAR built around an Arduino microcontroller-named PARduino. PARduino provides for widely distributed sensor arrays and tests the feasibility of using open-source, hobbyist-grade electronics for collecting scientific data. PARduino components include a quantum sensor, an EME Systems signal converter/amplifier and an Arduino Pro Mini microcontroller. Additional components include a real-time clock, a microSD Flash memory card and a custom printed circuit board. The components were selected for ease of assembly. We found strong agreement between the PARduino datalogger system and National Institute of Standards and Technology traceable sensors logged by an industry standard datalogger (slope = 0.99, SE < 0.01, P < 0.01; intercept = - 14.84, SE = 0.78, P < 0.01). The average difference between the two systems was 22.0 µmol m(-2) s(-1) with PARduino typically underestimating PAR. The average percentage difference between systems was 3.49%. On average, PARduino performed within the factory absolute calibration of the PAR sensor; however, larger errors occurred at low PAR levels. Using open-source technologies such as this can make it possible to develop a spatially distributed sensor network within the constraints of a typical research budget.
authors.affiliation: Department of Geography, Institute of Arctic and Alpine Research, University of Colorado at Boulder, Campus Box 450, Boulder, CO 80309, USA holly.barnard@colorado.edu.
authors.forename: Holly R
authors.initials: HR
authors.lastname: Barnard
authors.affiliation: Department of Geography, Institute of Arctic and Alpine Research, University of Colorado at Boulder, Campus Box 450, Boulder, CO 80309, USA.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Findley
authors.affiliation: National Ecological Observatory Network, Inc., 1685 38th St., Ste. 100, Boulder, CO 80301, USA.
authors.forename: Janae
authors.initials: J
authors.lastname: Csavina
mesh_terms: D002138:Calibration; D005240:Feasibility Studies; D065928:Forests; D008027:Light; D010788:Photosynthesis / Q000528:radiation effects*; D011874:Radiometry / Q000191:economics / Q000295:instrumentation* / Q000592:standards; D013997:Time Factors
keywords: Arduino; calibration; data acquisition; datalogger; open source