The LTER Executive Board recently formed an Ad-hoc Remote Sensing Committee to review the LTER remote sensing data archive, the data requirements, and coordination and support from the LTER Network Office (LNO). The Committee consisted of Andrew Fountain (MCM) as chair, Morgan Grove (BES), Mark Williams (NWT), Dave Verbyla (BNZ), and John Vande Castle (LNO) as an ex-officio member. The committee made a number of recommendations on ways to improve access to remote sensing data and information for the Network:
- that LTER form a "Spatial Data and Analysis Committee" to focus coordination by LNO and the LTER sites, and enhance top-down and bottom-up information flow within the LTER Network. To assess the specific needs for remote sensing data and coordination by the sites and the Network, LNO should survey all sites on their current remote sensing data holdings and spatial data needs. Although the Committee focused primarily on site needs, the LNO survey could include needs for data that contribute to needs of the LTER Decadal Plan and Integrative Science for Society and the Environment (ISSE) research. The past and planned cyberinfrastructure needs and assessment surveys provide some background information for this, although not in the detail suggested by the Committee.
- that LNO continue to facilitate communication on spatial data and analysis at several levels between LTER sites, key investigators, and agencies. For example, LNO should continue coordinating planning efforts for proposed future NASA satellite missions -- such as the DESDynyl spacecraft to provide LIDAR (Light Detection and Ranging) and Synthetic Aperture Radar remote sensing data, and the HyspIRI (Hyperspectral Infrared Imager) mission to provide space-borne hyperspectral and multispectral thermal imaging data for ecological research.
- that LNO lead in developing cooperative agreements to acquire LIDAR data for sites, and arrange for hyperspectral imagery (such as AVIRIS -Airborne Visible/Infrared Imaging Spectrometer data) for all sites on repeated intervals and during special disturbance events. Access to LIDAR data from the NSF-funded NCALM (NSF Center for Airborne Laser Mapping) program would also be an excellent contribution for Decadal Plan/ISSE research. LNO should also continue to provide links to data from other agencies, such as MODIS direct broadcast imagery, MODIS time series data subsets, imagery of LTER sites from the International Space Station, and the Global Fiducial reconnaissance data for LTER sites awaiting future declassification.
- that LNO act as a clearinghouse for information related to new and emerging technologies, for new spatial data, and for data available in historic archives. With the help of the LTER Information Management and NISAC Committees, this information could include aerial photographic imagery available for and acquired by LTER sites, as well as data from the National Agricultural Imagery Program, the US Department of Agriculture’s Forest Service, and individual State governments. Another example would be information on the availability of data from the National Aerial Photography Program (NAPP) and National High Altitude Photography (NHAP) aerial collections, which are available at no charge for online download. The committee also suggested a common access through LNO to online and offline information on the remote sensing holdings already acquired by each LTER site.
- that LNO review and obtain cloud-free Landsat images for all LTER sites. The Committee focused on the Landsat-5 record, whose data is available from 1984 to the present. Although previous Technology Committee meetings have made a similar recommendation, such an archive has not been practical because of licensing and costs issues. However, that is no longer the case because, for the first time in history, the data are available at no cost and without license restrictions. So reviewing the entire Landsat record and obtaining cloud-free images would be an excellent service that LNO could provide the Network. The Committee considered the Landsat archive very valuable to individual LTER sites, but it can also provide a powerful database to support Decadal Plan and ISSE research.
Data from Landsat-4 and Landsat-7 could also be considered because that would improve and extend the record from 1982 to the present. The Landsat-7 data was far superior to that of Landsat-5 until technical problems degraded the data in 2003. Landsat -7 also contains a 15 m panchromatic band that is quite valuable for LTER spatial analysis. An archive of the best Landsat data in practice translates to about four to five images per year for most LTER sites. The Arctic, Antarctic, and tropical sites might have only four or five usable scenes in the entire Landsat record because of acquisition difficulties, while sites in the southwestern United States might have as many as 14 cloud-free scenes per year. Some sites might also require more than one Landsat scene to cover the entire site. It is clear that further discussion is required on the number of scenes, length of the archive record, and how the data are stored since these issues are important to the feasibility and costs associated with the archive.
By Andrew Fountain, MCM,
& John Vande Castle, LNO