 |
|
 |
|
|
|
 |
Equipment Descriptions
Dataloggers: Each LAIS station is equipped with a model CR23X datalogger manufactured by Campbell Scientific. A datalogger is a specialized computer which accepts electronic signals from various instruments, performs mathematical functions on the data, and records summaries in internal memory at designated intervals.
Communication: Most stations transmit data to a centralized computer every five minutes by using a combination of RAD brand short-haul modems, buried communications cable, and a Lantronix UDS-10 network interface. Some stations have radios substituted in place of the buried cable, and some still use telephone modems. Where the network interface and the weather station are not within the same local calling area, data is generally transmitted only once per day.
Power: The dataloggers operate on 12 volts direct current. In most cases, this is provided by an internal battery that is kept fully charged by a 30-watt solar panel. In some cases, the internal battery is kept charged by an adapter plugged into a regular 110-volt AC outlet. Some stations substitute a larger gelcell battery for the internal battery.
Soil Temperature: Most stations have four Type T (copper-constantan) thermocouples at depths of 0 (just barely covered by dirt), 5, 10 and 25 cm, in the center of bare soil plots at least 8 feet square.
Air Temperature and Relative Humidity: A dual sensor measures temperature and relative humidity. Each station has a Vaisala HMP35A, which has a platinum temperature sensing element, and a Humicap relative humidity sensor.
Backup Air Temperature:All stations have a second temperature sensor to help in judging the quality of the primary temperature sensor's data. If both temperatures agree, it is unlikely that they are far off from actual air temperature. In many cases, the backup sensor is identical to that used in National Weather Service electronic Maximum Minimum Temperature Systems. All stations will soon have the Campbell Scientific 107 thermistor as the backup, along with a matching sensor at a height of 9 meters.
Solar Radiation: Solar radiation is measured with a LiCor pyranometer at every station.
Photosynthetically Active Radiation (PAR):Many stations have a LiCor quantum sensor that measures that portion of sunlight that is photosynthetically active.
Wind Speed and Direction: All stations measure both wind speed and direction with an RM Young Wind Monitor, configured for use with Campbell Scientific dataloggers, at a height of 10 meters. At most locations, wind speed and direction are also measured at 3 meters. In this case the sensors are a Met One 014 anemometer and a Met One 024 vane. As an additional note, an indicated "North" wind is a wind that is generated from the North traviling towards the "South"
Precipitation: All stations have Handar 444A tipping bucket rain gauge or a similar unit manufactured by Hydrological Services. Either brand transmits a signal to the datalogger each time .01 inches of rainfall accumulates. Many of the stations also have an official manual precipitation gauge in the same location.
Barometric Pressure: All stations in the LAIS network also observe barometric pressure.
 |
© Copyright 2002 LSU AgCenter All Rights Reserved
|
 |
|