12/04/2019
SatAgro’s “Explorer” offers a convenient way to analyze past weather and it’s impact on our farm. The data you can display goes back to the beginning of the century.
By default, the timeseries assigned to your field come from the closest publicly available weather station, usually operated by government agencies. To check which station your field has been assigned to, go to the “Field sheet” – the station will be stated in the lower right of the “Monitoring” panel.
Premium subscription SatAgro Users who own a private, web-enabled weather station can have weather data integrated with their SatAgro account.
If you prefer non-metric temperature and precipitation unit systems, you can change to imperial in the settings.
Weather timeseries available in SatAgro
Temperature
Calculated as the average daily temperature centigrade, displayed along with an envelope of maximum and minimum recorded temperatures on that day of the year.
Growing Degree Days (GDD)
A very useful variable in agronomy, closely with development stages of plants. This sum is calculated as the sum of all surpluses of average daily temperature above a threshold temperature – 5°C.
For example, the following timeseries of temperature:
| Date | Temperature |
| January 1st | 4°C |
| January 2nd | 6°C |
| January 3rd | 7°C |
Will at the end of January 3rd give a GDD value of:
(4 – 5) + (6 – 5) + (7 – 5) =
= (-1 → 0) + 1 + 2 =
= 3
Crop based GDD
The GDD index variable adjusted to the specific properties of a given crop. Specific crops have differing temperature thresholds, above which they are able to grow. Winter crops have the lowest thresholds (0-4 centigrade), while corn is an example of a warmth-dependent crop (8-10 centigrade). The indexes value is highly correlated with a plant’s growth stages, which makes it especially useful for planning the way you manage your crop. For the index to be calculated properly you have to enter an accurate crop history into the system – this gives the app information on sowing and harvest dates, as well as the threshold temperatures.
Precipitation
The daily sum of precipitation in mm (or liters per square meter).
Precipitation cumulative
Yearly sum of precipitation up to given date in mm. This index makes it easier to compare weather conditions between seasons and keep track of the amount of water available to your crops.
Crop based precipitation
Analogously to Crop based GDD, this is the sum of precipitation from the moment of sowing of a given crop, reset to 0 upon harvest.
Evapotranspiration (ET)
A measure of the possible amount of water removed from the ground per day. It is a more complex variable, calculated on the basis of a series of measurements (temperature, atmospheric pressure, wind speed, insolation, humidity). ET gives us useful information about the water conditions at the moment, but it is important to remember the limitations of this measurement. ET is the value of potential evaporation, i.e. it does not take into account the actual available soil water reserves. The formula is calibrated for 12 cm grass.
