The North American Land Change Monitoring System (NALCMS) was developed to depict information about land cover - the observed physical cover on the surface of the earth - and land cover change in a seamless, consistent, and automated way across North America at regular intervals.

The NALCMS is a collaborative effort of government agencies in Canada, Mexico and the United States coordinated by the Commission for Environmental Cooperation's North American Environmental Atlas initiative. Based upon the analysis of images collected remotely by satellites, the NALCMS seeks to be a dynamic land cover change monitoring system and a vital long-term information source for users of land cover change products across North America.

How is it unique?

NALCMS is unique in that the entire system was developed to meet the collective needs of the three North American countries and users of North American data. It is accurate, of known quality and is being developed with expertise from all three countries. The NALCMS uses a common strategy and framework to generate consistent results across North America facilitating continental applications and monitoring.

Practical application

Information about land cover change across North America is valuable for a range of audiences, including decision makers, international organizations, nongovernmental conservation organizations, land managers, and scientific researchers. 

NALCMS products can be used for a variety of applications including: Carbon sequestration analysis, wildlife habitat mapping, ecosystem monitoring, environmental planning, weather forecasting, water quality assessments and biofuels production potential. 

The land cover maps of the NALCMS serves as a valuable land change indicator for North America to help us better understand the dynamics of the changing North American environment. 

Products

The first NALCMS products are the Land Cover 2005 map and the satellite imagery showing Seasonal Land Cover Change in 2006. Upcoming NALCMS products will include updated land cover maps at regular intervals and change detection products.

Sources of the data

The NALCMS uses data from a remote sensing instrument called MODIS, the Moderate Resolution Imaging Spectroradiometer. MODIS collects information about the surface of the earth by sensing and recording reflected or emitted energy. The MODIS instruments are part of the National Aeronautics and Space Administration's (NASA) Earth Observing System.

The MODIS instrument from which the data are collected is aboard the Terra satellite. MODIS acquires images of the entire surface of the earth every one to two days, in 36 spectral bands (groups of wavelengths), ranging from 0.4 to 14.4 µm. The MODIS instrument takes measurements continually, and in a very wide field of view (the width of the satellite's viewing swath is 2,330 km). Terra travels from north to south across the equator in the morning.

MODIS' measurements are taken at three different levels of spatial resolution: 250 meters, 500 meters, and 1000 meters. The resolution is the area represented by each pixel of an image; a resolution of 250 meters means that each pixel represents a 250 meter x 250 meter piece of the earth's surface. The smaller the resolution, the more detailed the image.

Data from MODIS are transferred to ground stations in New Mexico and are then sent to the Earth Observation System Data and Operations System (EDOS) at the Goddard Space Flight Center near Washington, DC, where the data are processed and distributed. The NALCMS acquires the MODIS data by downloading it from NASA.

Because the MODIS data files are very large, data storage needs and data download time are significant. For the NALCMS development phase (2005-2007), the required data storage capacity for the MODIS data is approximately 50 TB (50,000 GB). 

Before the NALCMS can use the MODIS data to create maps of land cover, the data needs to be processed. The creation of land cover and land cover change maps using remotely sensed data is an extremely complex process with many steps and decisions. For details about the processing steps, please contact the NALCMS partners.