RainMachine Mini User Manual
6.
Appendix 1
6.1. Evapotranspiration (ET)
Evapotranspiration accounts for the amount of water lost to the atmosphere as a result of
evaporation (both from soil and plant leaves) and transpiration from the plant tissues. Using
ET, the RainMachine estimates how much water your lawn, garden and trees need to grow
healthy. To learn more about evapotranspiration, please consult:
http://en.wikipedia.org/wiki/Evapotranspiration
RainMachine downloads weather forecast data from NOAA
*
and using a complex algorithm,
it calculates ET and estimates the water needs for the next days. NOAA provides forecast
data for the entire US with a 5 km (approx. 3 miles) spatial resolution, allowing RainMachine
to predict the watering adjustments.
*
National Oceanic and Atmospheric Administration
http://www.noaa.gov
Note: Unlike other smart sprinkler controllers, RainMachine uses free weather data from
NOAA’s National Weather Service, a governmental agency paid from your tax dollars. You
will never pay fees for accessing weather data.
6.2. Quantitative Precipitation Forecast (QPF)
After estimating the water loss, RainMachine takes into account the estimated amount of rain,
with spatial resolution of 5 km.
QPF is the expected amount of melted precipitation accumulated over a specified time period
over a certain area.To learn more about QPF, please refer to:
http://www.hpc.ncep.noaa.gov/qpf/qpf2.shtml
Note: QPF becomes better as we approach the event (e.g.: the rainfall). Better results on
saving water can be obtained if your program frequency is less than 3 days.
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