North American Overlay Mapping
Layer Notes - Satellite Photograph
The background layer 'Photo' is extracted from NASA's 656MB 43200x21600 pixel tiff image 'land_shallow_topo'; its scale of 120 pixels per degree determined the choice of scale for NAOMI. This spectacular 'Blue Marble' image, a composite of Land Surface, Shallow Water, and Shaded Topography, is the most detailed true-color image of the entire Earth to date. Using a collection of satellite-based observations, scientists and visualizers stitched together months of observations into a seamless, true-color mosaic of every square kilometer of our planet.
Much of the information contained in this image came from a single remote-sensing device-NASA’s Moderate Resolution Imaging Spectroradiometer, or MODIS. Flying over 700 km above the Earth onboard the Terra satellite, MODIS provides an integrated tool for observing a variety of terrestrial, oceanic, and atmospheric features of the Earth.
The land and coastal ocean portions of these images are based on surface observations collected from June through September 2001 and combined, or composited, every eight days to compensate for clouds that might block the sensor’s view of the surface on any single day. Two different types of ocean data were used in these images: shallow water true color data, and global ocean color (or chlorophyll) data.
Topographic shading is based on the GTOPO 30 elevation dataset compiled by the U.S. Geological Survey’s EROS Data Center. MODIS observations of polar sea ice were combined with observations of Antarctica made by the National Oceanic and Atmospheric Administration’s Advanced Very High Resolution Radiometer sensor, or AVHRR.
A variety of different sized images covering the whole world can be downloaded from this website:
- NASA Goddard Space Flight Center Image by Reto Stöckli (land surface, shallow water).
- Enhancements by Robert Simmon (ocean color, compositing).
- Data and technical support: MODIS Land Group; MODIS Science Data Support Team; MODIS Atmosphere Group; MODIS Ocean Group
- Additional data: USGS EROS Data Center (topography); USGS Terrestrial Remote Sensing Flagstaff Field Center (Antarctica).
- Satellite: Terra
- Sensor: MODIS