The Arable Mark: Accuracy and Applications January 7, 2018
Overview Physical and Biological Observations Precipitation Air temperature, humidity, pressure Shortwave (SW) radiation (down & upwelling) Longwave (LW) radiation (down & upwelling) Seven-band spectrometer (up and down) Band 1: 440-510 nm Band 2: 515-555 nm Band 3: 565-595 nm Band 4: 620-690 nm Band 5: 690-740 nm Band 6: 780-900 nm Band 7: 930-960 nm Photosynthetically active radiation (PAR) Contextual and Health Observations GPS coordinates Acoustic sonogram (sound classification) Tilt, compass, acceleration Voltage, Charge RSSI Derived data (examples) Net radiation (Rn) from SW and LW radiometers ETo from radiometers and static air properties ETc from ETo and canopy cover Leaf temperature from upwelling longwave Surface wetness from leaf temperature Disease risk from leaf wetness and temperature Frost risk from net longwave balance Canopy cover and biomass from spectrometer* Growth rate from change in canopy cover* Canopy nitrogen content from spectrometer* Light use efficiency from spectrometer* Flowering and pollination from spectrometer* Photosynthesis (A) from PAR, fapar, and LUE* * benefits from variety-specific calibration Advantages of the Arable Mark versus a conventional weather station: Integrated modem, power, and mounting dramatically reduces installation burden Measures not only conventional weather, but also drivers of crop performance (ET, A), as well as crop response to drivers (growth, reproduction, stress, nutrient and water status) Measures not only static air properties (temp, humidity, rain) but also surface fluxes (Rn, H, LE) Measures of agronomic importance (ET, disease risk, frost risk) Backfill and infill from weather model to enable complete seasonal view of heat accumulation versus a weather model: Enables bias correction for Point Forecasts of T, precip and crop metrics like ET and disease versus a drone: Continuous measurements enable integration in time (e.g. heat accumulation) and ephemeral events (e.g. frost, heat spike, rain event) that are essential for forecasts versus a satellite: Continuous and high fidelity spectroscopy unlocks value of infrequent and error-prone imagery
Accuracy Measurement Setting UNL Ameriflux Site, Mead NE, June 2016, 5m above a field of soybeans (Glycine max) Rutgers University Photochemical Assessment Monitoring Site (a) at New Brunswick, NJ in August, 2016 Reference Instruments Vaisala HMP50 Temperature and Relative Humidity Sensor (Vaisala Instruments, Vantaa, Finland) RM Young 61302V (RM Young, Traverse City, MI) R 2 = 0.99 R 2 = 0.95 R 2 = 0.99 Measurement Mark Sensor Accuracy Mark to Reference Relative Accuracy Reference Manufacturer Accuracy Air Temperature ± 0.75 C over the range -40 to 125 C 4% of measurement (mean relative error ± one σ) ± 1.5 C over the temperature range -40 C to 60 C Relative Humidity ± 3% RH over the range 0 to 100% 6% of measurement (mean relative error ± one σ) ± 3% RH over the range 0 to 90% RH and ± 5% over the range 90 to 95% RH Barometric Pressure ± 4 mbar over the pressure range 500 to 1100 mbar 0.1% of measurement (mean relative error ± one σ) 0.05% over analog pressure range (± one σ)
Accuracy Measurement Setting UNL Ameriflux Site, Mead NE, June 2016 Rutgers University Photochemical Assessment Monitoring Site (a) at New Brunswick, NJ in August, 2016 Reference Instruments Kipp and Zonen CM3, CNR4 Net Radiometer (Kipp and Zonen B.V., Delft, The Netherlands) LI-190 Quantum Sensor (LI-COR, Inc. Lincoln, NE) R 2 = 0.98 R 2 = 0.87 R 2 = 0.98 Measurement Mark to Reference Relative Accuracy Reference Manufacturer Accuracy Shortwave Energy Longwave Energy 4% at the daily total level of downwelling energy (mean error ± one σ) 4% at the daily total level of upwelling energy (mean error ± one σ) 5% at the daily total level (95% confidence interval) < 10% at the daily total level (95% confidence interval) Net Radiation 10% at the daily total level (mean error ± one σ) Not stated PAR 6% at the daily total level (mean error ± one σ) ± 5% traceable to the U.S. National Institute of Standards and Technology
Accuracy Measurement Setting UNL Ameriflux Site, Mead NE, June 2016 Rutgers University Photochemical Assessment Monitoring Site (a) at New Brunswick, NJ in August, 2016 Reference Instruments B&W Tek i-trometer Portable Spectrometer (B&W Tek, Newark, DE) Instruments SA, Inc. Monochromator Spectrometer bands relative to solar spectrum Absorption kernels of spectrometer bands
Accuracy
Applications: Mounting Strawberry Center Pivot Tea Celery Vineyard Orchard
Applications: Mounting Hops Research Potatoes Rangeland
Applications: Water Cycle ETo, Kc, and ETc Measurement Setting UNL Mesonet (Brule N, Brule S), June-July 2017 R 2 = 0.72 MAE = 0.85 mm/day Reference Instruments Vaisala HMP50 RM Young 61302V Li-200 Pyranometer Water Potential Measurement Setting Various CA Vineyards Aug 2017 Reference Instruments PMS Model 1505D Pressure Bomb
Applications: Disease Liquid water and temperature sensitivity define many pathogens Downy Mildew Powdery Mildew Apr May Jun Jul Aug Sep Oct
Applications: Crop Monitoring and Prediction
Applications: Spatial Analysis 6/6/2017 Satellite 6/12/2017
Applications: Short term weather extremes Frost, Heat, Scald