Section 1. Introduction to the LI-710
The LI-710 uses eddy covariance calculations that are optimized for the hardware
and sensor configuration. It combines vertical wind speed measurements with high-
precision relative humidity measurements to compute evapotranspiration from the
area surrounding the sensor. When the prevailing wind directions around the LI-710
are random or uniform, measurements represent the surrounding area and veget-
ation (known as the “fetch footprint”). When wind is from a prevailing direction,
measurements represent the land area and vegetation under the prevailing winds.
The fetch footprint encompasses an area around the LI-710 that is 50 to 100 times
the height of the sensor (e.g., a 2-meter height above the canopy has a fetch foot-
print of 100 to 200 meters).
The LI-710 does not provide horizontal wind information and therefore, it does not
report the fetch footprint of the measurement. In a proper deployment, the foot-
print will encompass a uniform land area surrounding the sensor or an area upwind
of the prevailing wind direction (see Deploying the LI-710 on page2-1 for more
information).
What's what
If you have just received your LI-710, check the packing list to be sure you have
everything that you ordered. The LI-710 may include some or all of the following
components.
Evapotranspiration sensor
Part number
9971-010
The sensor features one cable connector for power and data and one mounting post
for mounting onto a tripod or meteorological sensor platform using a 1" (2.54 cm)
cross-over fitting.
Data and power cable
Part number
392-19605
Each sensor includes a 5-meter long combined data and power cable. The cable con-
nects to the SDI-12 terminals on a datalogger.
Spares kit
Part number
9971-008
Each LI-710 is shipped with a spares kit, which includes replacement parts and a tool
for the instrument. See Table 1-1 on the facing page for a complete list.
1-2 LI-710 Evapotranspiration Sensor Instruction Manual
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