This Snapshot of Coastal Processes in Australia is Lovely and Surreal

This striking image isn't a piece of watercolour abstract art. It's an estuary in Western Australia and a gorgeous example of utility of data beyond the visible spectrum. By combining wavelengths from deep blue through infrared, this Landsat image can be used to asses coastal processes and vegetative health.

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One of the things I love about Landsat imagery is that the data extends beyond the visible wavelengths. With the most recent satellite, Landsat 8, collecting in 11 distinct bands, image processors have a wealth of data to mix and match in order to highlight specific environmental processes.

Landsat 8 carries two instruments: the Operational Land Imager (OLI) and a Thermal Infrared Sensor (TIRS). The OLI captures the same visible, near infrared, and shortwave infrared wavelengths as earlier Landsat satellites, with additional detectors for deep-blue (Band 1) and infrared (Band 9). The TIRS collects long-wavelength infrared data at a lower resolution. Each wavelength band has particular functionality: investigating the coastal zone and aerosols (Band 1), highlighting active fires (Band 6,7), evaluating vegetation health (Bands 3, 6, and 7), or identifying clouds.

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This particular image goes beyond the typical "Remap three bands to red-green-blue and get on with our lives" simplicity of most false-coloured images. Instead, the land and water were masked and viewed with separate wavelength bands with data captured by OLI. Land is short wavelength infrared, near infrared, and green, to highlight vegetation health, while water is red, blue, and ultra-blue bands to highlight sediment and nutrient patterns in shallow water. Bright green vegetation is happy and healthy, while the yellower and even brown vegetation on the slopes farthest from the estuary is downright stressed. Within the water, the deepest blue is clear, deep water, fading to yellow in the muddy estuary, and into bright red in muck thick enough to steal boots off unwary visitors.

Why bother doing something so complicated when you could just map out two images? The acquisition date date is a hint: 12 May 2013. Landsat 8 wasn't declared fully operational until two weeks later, on May 30th. This image with its complex processing was part of the calibration and verification stage of the satellite, running it through its paces to see what it could do.

Table credit: USGS. Image credit: NASA/USGS Landsat/Geoscience Australia. Want it bigger or different dimensions? Here it is in 1920x1200 and 1600x1200.




Slight correction, Mika — Landsat 8 collects in 11 spectral bands. TIRS has two bands in the thermal IR, centered around 10.8 microns and 12.0 microns. The 12.0 micron band (band 11) isn't used very often, but it's there.

By the way, I can pass you a rumor that we have been turned on for an Earth as Art 4 project, so we'll soon be making another round of artistic images for display in art museums. I've already submitted about 20 candidates. I might put some on my Flickr account, as I have for the previous Earth as Art runs. Should be a nice collection.