The CALMIT "SpecLab" provides a facility for collecting spectral data under controlled, experimental conditions. SpecLab provides research facilities, storage space for the field program, and office space. At the core of the facility is "dark room" where spectral measurements can be made in a systematic fashion. Several types of spectroradiometer systems can be mounted in a very convenient, yet controlled, manner using a versatile, ceiling-mounted "sensor platform." A variety of laboratory equipment is available to researchers and students including a Shimadzu UV-2501PC (UV-VIS) recording spectrophotometer and a LI-COR 3100 area meter.
Supplemental artificial light for culturing algae and plants is provided by numerous 400W metal-halide lights, while spectral measurements are made using 500W halogen lights. SpecLab also contains facilities and equipment for analyzing water samples as well as large ovens for drying vegetation samples.
Field Research Facility
The CALMIT Field Research Facility (CFRF) is located at the University of Nebraska Agricultural Research and Development Center-Ithaca (ARDC), which is about 35 miles north and slightly east of Lincoln, near Mead, Nebraska
The ARDC is a 9,000-acre experiment station, operated under the aegis of the Agricultural Research Division of the Institute of Agriculture and Natural Resources.
The field remote-sensing program is one of the major program areas under the aegis of CALMIT. An impressive array of facilities and equipment combine to provide faculty, staff, students, and visiting scientists with an unusual opportunity to conduct field-oriented investigations. The emphasis of the field activities is on close-range remote sensing, but data collected by means of many other related technologies can be linked to the spectral data.
Aerial Remote Sensing Platform
CALMIT staff members, in cooperation with the UNL Department of Electrical Engineering and the UNO Aviation Institute, developed (2001) an aerial remote sensing platform for collection of spectral data. The platform is a Piper Saratoga, which over the years has undergone extensive modifications to facilitate the deployment of sensors. The AISA-Eagle (AE) Hyperspectral Imager (VNIR) is the primary on-board sensor. The AE covers the visible and near infrared portions of the electromagnet spectrum (between 400 and 1000 nm) and can be programmed to acquire up to 512 spectral channels at spatial resolutions from 0.75 to 2.5 meters.
All-Terrain Terrestrial Vehicle Data Collection Platform
CALMIT staff have constructed a unique, versatile all-terrain instrument platform, which is being used primarily for collecting spectral data in agricultural/cropland environments. The system, referred to as "Hercules," has great potential for "precision-agriculture" applications. "Hercules" provides a high-clearance mechanism for making measurements such as spectral reflectance in field settings. The pertinent characteristics of the Hercules platform include a ground clearance of 72 inches, a width of 120 inches, and wheels positioned for movement through crops with 30-inch rows.
The working platform on Hercules is 10 x 10 feet. The Hercules platform itself has a driver's seat and four scientist desks. Thus, up to five passengers/scientists can be accommodated during data-collection missions. The ample desk space allows instrument operations to be executed easily and efficiently. The instrument package can be raised to a height of approximately 50 feet above the ground surface, and rotated through a full circle around the platform.
The boom can be lowered nearly to ground level to accommodate either sensor attachment or calibration by means of a reference panel on, for example, a tripod. The maximum sensor payload for the boom, at full extension, is ~60 pounds. The operator has complete control of the sensor position from the deck. That is, the operator not only has control of the boom, and thus sensor field-of-view, but also the nadir or off-nadir position of the sensor. That view angle can be changed and verified easily and quickly.
CALMIT operates a 24-foot pontoon boat, which has been specially modified for collection of spectral data above, at, and beneath the surface. The boat provides an excellent workspace for data collection on lakes and reservoirs.
In addition to equipment for monitoring radiation fluxes, the boat carries a GPs receiver, onboard computing, and portable water-quality and analysis equipment. Researchers often operate our numerous pyranometer, terrestrial-quantum, and underwater-quantum sensors when collecting spectroradiometer data in the field.
In the case of the underwater sensors, upwelling and downwelling PAR are typically measured at two different depths, as a means of calculating the rate of extinction of light in lakes and reservoirs. The boat can be safely towed over long distances to facilitate study of distant aquatic systems. Water samples are typically collected and analyzed in support of our remote-sensing research on lakes and reservoirs. Detailed analyses of plant pigments, specific cations and anions, and other parameters are available through our own facilities, those of our research partners, and other university collaborators. CALMIT owns portable analysis equipment including instrumentation for measuring conductivity, turbidity, alkalinity, and other physicochemical parameters. A portable laboratory, with a spectrometer and reagent chemicals, provides additional measurement capabilities. With the portable and lab-based instrumentation, we are able to make measurements on-site, on a same-day basis, at remote locations and/or in a clinical-laboratory setting. This affords repeatable water sampling linked directly to remotely sensed data either from our spectroradiometers or in conjunction with aircraft/satellite overpasses.
In 1995, our first Ocean Optics PSD1000-C spectrometer was purchased. This instrument collected 1100 discrete channels of information from 300 to 900 nm, using two fiber-optic cables. The two cables are configured in a manner analogous to the SE-590 systems, so that simultaneous incoming and reflected solar irradiance are measured. In 2001, four Ocean Optics USD-2000 systems were acquired, and since that time, much of our day-to-day data collection is done with these spectroradiometers mounted on Hercules, boat platforms, and even underwater. Having two dual-fiber systems allows for simultaneous data collection by two field crews. We now have 11 Ocena Optics instruments,
The first Analytical Spectral Device (ASD) FieldSpec FR system, purchased in early 1998, provides hyperspectral coverage from 350 to 2500 nm. The additional capability in the mid-infrared spectrum is important with regard to staff research involving agricultural vegetation. The system was configured to allow positioning both on the boom of the Goliath vehicle and by one individual carrying it on foot into the field. The ASD can be used for assessing vegetation at both canopy and leaf levels (with optional leaf clip). A second ASD-FR was acquired in 1000.
In 2001, CALMIT purchased a UniSpec radiometer capable of collecting data in 256 channels ranging from 300 to 1100 nm. The UniSpec provides us with capability for not only assessing water quality but also vegetation at leaf-level.