Geodeziya, kartografiya, geografiya

Bands 10 and 11 are in the thermal infrared, or TIR – they see heat. Instead of measuring the temperature of the air, like weather stations do, they report on the ground itself, which is often much hotter. A study a few years ago found some desert surface temperatures higher than 70 °C (159 °F) – hot enough to fry an egg. Luckily, LA is relatively temperate in this scene:

Notice that the very dark (cold) spots match the clouds in Band 9. After them, irrigated vegetation is coolest, followed by open water and natural vegetation. The burn scar near Malibu, which is covered in charcoal and dry, dead foliage, has a very high surface temperature. Within the city, parks are generally coolest and industrial neighborhoods are warmest. There is no clear urban heat island in this scene – an effect that these TIR bands will be particularly useful for studying.

Let’s make another false-color image by using this TIR band for red, a SWIR band for green, and the natural green band for blue (a 10-7-3 image):

Urban areas and some kinds of soil are pink. In the true-color image, wild vegetation is almost uniformly olive-colored, but here we see a distinction between peach-colored scrubland, mahogany-colored woodland, and so on. Cooling onshore breezes appear as a slight purple gradient along the coast of the city. The colored strips on either side of the image are areas where not all sensors have coverage.

More to Come

Everything we’ve seen here is from a single one of the 25,000+ scenes already in the NASA/USGS Landsat 8 archives – each one indexed, documented, and free to use for any purpose. Every day, another 400 gigabytes of imagery arrive. The potential of this open, ever-growing dataset is huge, and I hope you’ve seen something here that encourages you to use Landsat 8 data yourself. Follow @MapBox on Twitter for a followup post on techniques, where we’ll cover how to use open-source tools to select, download, and process Landsat 8 scenes from concept to final product.

http://landsat.usgs.gov/band_designations_landsat_satellites.php 2. http://landsat.gsfc.nasa.gov/?page_id=5377 and 3. https://www.mapbox.com/blog/putting-landsat-8-bands