Satellite band designations and principal applications
There is a diagram showing the band widths of a number of optical sensors here (opens in new window).
Visible Blue - TM Band 1
Designed for water penetration, making it useful for coastal water and lake bathymetry and sediment load mapping. Also useful for differentiation of soil from vegetation, and deciduous from coniferous flora; it is lower for vegetation and coniferous forest. Well fragmented and granular rocks (e.g. some shales, phosphates, evaporites) scatter blue light and result in a high band 1 (and sometimes 2).
Visible Green - TM Band 2, MSS Band 1, SPOT XS/XI Band 1, IRS LISS Band 1
Designed to measure visible green reflectance peak of vegetation for vigour assessment. Also used to map sediment concentration in turbid waters, and is higher for ferrous iron rich rock compared to ferric iron.
Visible Red - TM Band 3, MSS Band 2 to 3, SPOT XS/XI Band 2, IRS LISS Band 2
A chlorophyll absorption band important for vegetation discrimination. It is higher for rocks and soils rich in iron, especially ferric iron.
Atmospheric effects contribute strongly to the visible bands - band 1 may have up to a 70% contribution from sky radiance.
Near infra-red - TM Band 4, MSS Band 3 to 4, SPOT XS/XI Band 3, IRS LISS Band 3
Useful for determining healthy vegetation and for delineation of water bodies. Peaks strongly for chlorophyll in healthy vegetation, resulting in a characteristic 'red-edge' between bands 3 and 4. Vegetation stressed by seeped petroleum may cause a measurable shift in the 'red-edge'. In the absence of vegetation ratios of bands 1 through 5 show ferric / ferrous iron differences in rocks and minerals.
Short wave infra-red - TM Band 5, SPOT XI Band 4, IRS LISS Band 4
Indicative of vegetation moisture content and soil moisture. Contained water absorbs, resulting in lower values. Dry material results in relatively higher values. Also useful for discriminating snow and clouds (low for snow, high for clouds). In vegetation free areas band 5 varies according to the type of iron oxide present in rocks and soils, and is generally high for all alteration minerals.
Short wave infra-red - TM Band 7 (2.08 - 2.35um)
This band was selected for its potential for discriminating rocks and for hydrothermal altered zones for mineral exploration. Hydroxyl (OH) molecular bonds in minerals stretch and the resultant electronic vibration causes absorption of energy around 2.2um, resulting in marked low values in band 7 for clay-rich minerals. Carbonate rich materials can also cause the same effect. Silica rich materials, dust in the air and bare soil are often relatively high in band 7.
Thermal infra-red - TM Band 6 (10.40 - 12.50um)
Used for thermal mapping. Useful for heat intensity, vegetation and crop stress analysis and locating thermal pollution. It is usually higher for darker coloured rocks.