Current Conditions
Temperature
Ambient air temperature surrounding the device is measured using a carefully designed chamber that allows air to flow freely past the measurement sensor.
Humidity
Relative Humidity is the ratio of water vapor in the air relative to the maximum possible.
Pressure
Barometric pressure is the pressure of the atmosphere exerted on an object below. The Mark measures barometric pressure at the same frequency as air temperature and relative humidity, so will accurately represent changes in barometric pressure caused by changing weather conditions.
We present sea level corrected pressure using the following equation: Po=P*exp(H*g/(R*T)). Our Arable Mark measures H, P, and T. R and g can be considered constants.
Sunlight
Sunlight is the amount of shortwave energy received from the sun and sky at a specific point. Sensors measure shortwave energy continuously over the course of a day, and Arable integrates these instantaneous values to obtain total daily sunlight for a given location.
Today’s Forecast
Temperature
Ambient air temperature surrounding the device is measured using a carefully designed chamber that allows air to flow freely past the measurement sensor. Measurements are reported at 2m above ground.
Forecasted Precipitation
Forecasted Precipitation is taken from the state of the art weather forecast GEFS. It is a 115x115 km grid that is updated every 6 hours.
Observed Precipitation
Observed Precipitation is the amount of precipitation that the Mark has measured thus far in a 24-hour period counting from 12am. The Mark measures observed precipitation using a microphone which records the frequency and intensity of raindrops as they hit the dome.
Leaf Wetness (Condensation)
Last Wet
Time since the canopy was last wet.
Duration
Total amount of time the canopy has been wet over the past 24 hours.
10 Day Total Wet Hours
Total amount of time the canopy has been wet over the past 10 days.
Rainfall is not included in the Leaf Wetness calculation. This measurement calculates condensation occurring when air temperature reaches the dew point.
Water Stress
Leaf Temperature
Leaf Temperature is measured by a sensor that is pointed down toward the plant canopy. The Mark calculates the leaf temperature using an infrared energy signal from the canopy and a temperature of the detector within the Mark. Higher leaf temperatures are correlated with water stress due to less evapotranspiration. Evapotranspiration (ET) serves to cool the leaves.
Leaf Temperature - Air Temperature
Leaf Temperature minus Air Temperature is calculated using the difference between the surface temperature measured with the bottom infrared thermometer and the ambient air temperature.
Leaf to air temperature difference is based on the assumption that a canopy with available water transpires at its maximum potential resulting in a lower leaf temperature. When water becomes limiting, the leaf transpires less than maximum and the cooling effect of transpiration is reduced resulting in a higher leaf temperature.
Positive values denote surface temperatures above air temperature. Higher positive differences indicate greater water stress. Negative values denote surface temperatures below air temperature. At mid-day, negative values indicate the surface is cooler than ambient air temperature.
Leaf to Air Temperature 4 Week Trend
Leaf to Air Temperature hourly trends for over the past 4 weeks.
Plant Vigor
Chlorophyll Index
The Chlorophyll Index is a proxy for plant productivity and the chlorophyll and nitrogen content in the plant. The Mark’s spectrometer detects reflected light in the red edge and near infrared regions of the spectrum to calculate a Chlorophyll Index. A higher Chlorophyll Index is indicative of higher chlorophyll and nitrogen levels in the canopy and higher productivity in the plant.
Weekly % Change
Weekly % Change shows the percentage of change in the Chlorophyll Index from 7 days ago.
Chlorophyll Index 4 Week Trend
Chlorophyll Index daily trends for over the past 4 weeks.
NDVI
NDVI
NDVI, or Normalized Differential Vegetation Index, represents the amount of green growing material present. The Mark’s spectrometer detects reflected light in the red and near infrared regions of the spectrum to calculate NDVI. A higher NDVI is indicative of more canopy cover.
Weekly % Change
Weekly % Change shows the percentage of change in NDVI from 7 days ago.
NDVI 4 Week Trend
NDVI daily trends for over the past 4 weeks.
Water In
Forecasted Precipitation
Forecasted Precipitation is taken from the state of the art weather forecast GEFS. It is a 115x115 km grid that is updated every 6 hours.
Observed Precipitation
Observed Precipitation is the amount of precipitation that the Mark has measured thus far in a 24-hour period counting from 12am. The Mark measures observed precipitation using a microphone which records the frequency and intensity of raindrops as they hit the dome.
Water Out
Forecasted Evapotranspiration
Forecasted Evapotranspiration for 10 day window. Forecasted ET for a specific location is from the GFS weather forecast that is updated every 6 hours.
Observed Evapotranspiration
Observed Crop Evapotranspiration for each day in a 10 day window. Crop Evapotranspiration is the quantity of water lost through evaporation and transpiration above the plant canopy. This calculation relies on multiple inputs from the device including four component net radiation and site-specific microclimate characteristics, all of which are measured directly by the Mark. A value of 0 is indicative of a wet environment (usually following a storm) whereas a value of 10 indicates an environment that is rapidly transporting water into the atmosphere.