Introduction to the LI-710

The LI-710 Evapotranspiration Sensor measures the total transport of water from evaporation and transpiration over an area using automated eddy covariance flux calculations. The output from the LI-710 is evapotranspiration, energy flux, and other parameters in 30-minute increments. It uses the SDI-12 protocol to transfer data to an external data recorder.

Figure 1‑1. The LI-710 Evapotranspiration Sensor consists of two transducers for anemometric measurements and an air intake.

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 vegetation (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 footprint 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 footprint will encompass a uniform land area surrounding the sensor or an area upwind of the prevailing wind direction (see Deploying the LI-710 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 connects 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 for a complete list.

Table 1‑1. Spares and accessories that are included with the LI-710.
Description Quantity Part Number
Pump 1 286-17946
Pump O-ring; 16×1.5 mm VITON 75 1 192-18247
Pump O-ring; 29×2 mm VITON 75 1 192-18249
Screws; M3×0.5 20 Stainless Steel 4 151-18159
Hex key; 2.5 mm ball end 1 611-20555
Intake Filter Tool 1 6371-021
Intake O-ring; 14.5×1 mm FKM 75 5 192-09986
Intake Filters 5 6571-002

Replacement parts

The spares kit included with each LI-710 includes the parts listed in Table 1‑1. Additional replacement parts are available for purchase.

Filter pack

Part number 9971-015

Five replacement filters are included in the spares kit. Additional filter packs are available for purchase. The filter pack includes five filters and five O-rings.

Replacement pump

Part number 9971-016

One replacement pump is included in the spares kit. Additional pumps are available for purchase. The kit includes one pump, two O-rings, and four screws.

Accessories

The accessories below are available from LI-COR.

Extension cable

Part number 392-20529

25-meter extension cable with weather-resistant connectors on each end. Extends the data/power cable for a total length of 30 meters.

Crossover fitting

Part number 7900-342

The LI-710 can mount to a horizontal cross bar (1¼" outside diameter) with a ¾" × 1" crossover fitting.

Swivel mount

Part number 7900-344

The LI-710 can mount to a vertical mast (1" outside diameter) with a ¾" swivel mount.

Mounting kit with riser bar

Part number 7900-340

The mounting kit includes a crossover fitting (¾" × 1"), swivel mount (¾"), and a 56 cm (22") riser bar.

Figure 1‑2. The crossover fitting, riser bar, and swivel mount are available individually or as a kit.

Cross bar and mounting hardware

The following components can be used to add a cross bar to a mast with an outer diameter of 2.375" (about 6 cm).

Cross Bar (1): 1.5 m long, 3.3 cm OD Schedule 80 aluminum pipe 6061-T6.

Part number 9879-010

Mounting Plate: For mounting the cross bar to a mast.

Part number 9879-020

Brackets (4): For mounting the cross bar to the mast.

Part number 9879-043

Mounting Hardware Kit: For mounting the cross bar to a mast.

Part number 9979-018