The Global Land Cover Facility (GLCF) is an operational research and development project housed in the Department of Geographical Sciences, within the College or Behavioral and Social Sciences, at the University of Maryland. Funded primarily by NASA, GLCF has been involved in numerous research projects encompassing the fields of remote sensing, geospatial ecology, and information systems. Leveraging both custom off-the-shelf and in-house software solutions, GLCF over the past decade has become one of the largest online repositories and world-wide distributors of remotely sensed data. Instrumental to GLCF’s success is the ability to understand user requirements and build web-based interfaces to facilitate quick and timely delivery of terrestrial data and products. GLCF actively participates in local and international organizations and is a member of the Earth Science Information Partners, International Union of Conservation (IUCN), and the Open Geospatial Consortium (OGC).
GLCF houses roughly 50 terabytes of data online and provides users with two interfaces to access the data: Earth Science Data Portal (ESDI) and plain File Transfer Protocol (FTP). ESDI (version 2) is a web-based application developed in-house using Java (Java Servlets, Java Server Pages and Java Beans) tightly coupled with a spatial database backend that allows users to make text-based, temporal, and/or spatial queries to search and retrieve data quickly from the GLCF. Upon retrieving results from the query, users are pro-vided with a shopping basket, where they can quickly preview and download the data for their area of inter-est. GLCF has been computing its user and data volume statistics since August 2002 and. leveraging the two interfaces, GLCF has distributed over a petabyte of data to users worldwide, a milestone we crossed late in 2009.
GLCF changed the way remotely sensed data is used and distributed, including open-access policies and easy-to-use file formats. GLCF was one of the main contributors in helping the U.S. Geological Service reach the decision to make its Landsat archive open to the public in April 2008. Granting open access to data democratizes the Earth sciences, allowing users world-wide to build algorithms, models, and solutions that reveal insights into the Earth system. Of the top 10 users that the GLCF supports, the 6th largest were U.S. colleges and universities. Within the research community, the GLCF has been cited or acknowledged in over 2500 peer-reviewed journal articles on Google Scholar, countless other non-peer reviewed journals, various local and international atlases, books, and software applications.
The GLCF is currently working on various land-use and land-cover change mapping efforts using data from the Landsat series of sensors. The GLCF recently created the first globally consistent Landsat-based estimates of Earth’s surface reflectance and made the data publicly available online. The Global Forest Cover Change project, funded by the NASA MEaSUREs program, is mapping changes in Earth’s forest cover at sub-hectare resolution using the NASA/USGS Global Land Survey datasets circa 1975, 1990, 2000 and 2005. The GLCF will supply the earth-system modeling community a much needed high–resolution, multi-temporal record of forest cover that will be instrumental in monitoring and under-standing forest cover changes and their global implications.
Using similar approaches, the GLCF is mining the historical satellite data record to produce records of Earth’s growing urban cover. Although urban areas cover only 0.5% of Earth’s terrestrial surface, cities represent one of Earth’s fastest-growing land-use types on a per-area basis, and over half of the planet’s 7 billion humans now reside in cities. Urban “impervious surfaces” (i.e. buildings, roads, sidewalks, etc.) generate the “urban stream syndrome” of increased water temperatures and levels of sediments, heavy metals, nitrogen, phosphorous, and fecal coliform bacteria. Urban surfaces also generate the “urban heat island effect”, an increase in temperature due to replacement of vegetation with pavement and buildings. Urbanization is even associated with changes in human populations, including delayed reproduction and decreased birth and death rates. The GLCF is working with the NASA Goddard Space Flight Center to map urban growth globally from 2000 – 2010 and has developed a method to map urban growth at annual resolution from 1984 to 2010.
Throughout, the GLCF has been true to its core competency, making data and products reliably available to its user community. It hopes to continue that legacy for many more years to come.
By: Saurabh Channan