Processed Thematic Mapper satellite imagery for selected areas within the U.S.-Mexico borderlands

These processed Landsat satellite images provide high-resolution multispectral coverage of selected areas. The characteristics of the MSS and TM bands were selected to maximize their capabilities for detecting and monitoring different types of Earth resources. For example, TM band 2 can detect green reflectance from healthy vegetation, and band 3 of TM is designed for detecting chlorophyll absorption in vegetation. TM band 4 is ideal for near-IR reflectance peaks in healthy green vegetation and for detecting water- land interfaces. Wavelength of TM band 1 can penetrate water for bathymetric mapping along coastal areas and is useful for soil-vegetation differentiation and for distinguishing forest types. The two mid-IR red bands on TM (bands 5 and 7) are useful for vegetation and soil moisture studies, and discriminating between rock and mineral types. The thermal-IR band on TM (band 6) is designed to assist in thermal mapping, and for soil moisture and vegetation studies. TM Bands 7, 4, and 2 have been combined to make false-color composite images. This band combination makes vegetation appear as shades of red, brighter reds indicating more vigorously growing vegetation. Soils with no or sparse vegetation will range from white (sands) to greens or browns depending on moisture and organic matter content. Water bodies will appear blue. Deep, clear water will be dark blue to black in color, while sediment- laden or shallow waters will appear lighter in color. Urban areas will appear blue-gray in color. Clouds and snow will be bright white. They are usually distinguishable from each other by the shadows associated with the clouds. Exposed bedrock will appear in a wide range of colors depending on the composition and other factors.