Data Output
High Speed
The LI-7700 features direct Ethernet data output at up to 40 Hz. Data can be output directly to a computer or routed through a network connection or modem for remote access. Seven analog input channels are available for collecting data from a sonic anemometer and thermocouples.
Flexible Inputs and Outputs
The optional LI-7550 Analyzer Interface Unit provides for a variety of additional data output options, including SDM, RS-232, and high speed DACs for connection to data logging devices. The LI-7550 also provides four additional auxiliary input channels for connecting other sensors.
Onboard Data Logging
The LI-7550 Analyzer Interface Unit logs data to an internal removable USB storage device. High-speed data logging is easily configured to record methane measurements and data from numerous auxiliary sensors (e.g. sonic anemometer, LI-7500 Open Path CO2/H2O Analyzer) through the user interface software. Simply remove the USB storage device and plug it into a computer to view your data.
Sample Data:
Preliminary methane flux and ancillary data collected over a 23 day period in the Florida Everglades at a height of 4 m. Fluxes were obtained with the Eddy Covariance method using an LI-7700 Open Path Methane Analyzer and a CSAT 3-D Sonic Anemometer (Campbell Scientific).
Notice that wind speed and temperature correlate with methane flux and concentration. Nearly every night, reduced wind speeds lead to lower turbulent exchange, and lower temperatures are likely to reduce methane production. As a result, methane fluxes are reduced by a factor of 10, from about 2 mg m-2 h-1 during the day to about 0.2 mg m-2 h-1 at night. However, small fluxes still occur on calm nights, leading to a build-up in the concentration of methane in the ecosystem from about 1.26 mg m-3 to about 1.6 mg m-3. The build-up is eliminated in the mornings with increases in wind speed and turbulent exchange.