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Processed images from Earth orbiting spacecraft
Bjorn Jonsson
post Nov 15 2012, 12:37 AM
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For some reason it didn't come to my attention until recently (less than a year ago) that the entire Landsat imagery plus a lot of data from other Earth orbiting spacecraft is freely available for download at http://earthexplorer.usgs.gov/ . Maybe this is because for a long time it was more difficult to find good and freely available global maps (or get data to make maps) of the Earth than it was for other planets/satellites - I somehow was under the impression that the vast majority of Earth imagery was commercial.

The Earth is visually a really spectacular planet (in my opinion possibly even the most photogenic body in the entire solar system) so it's possible to get spectacular results by downloading some of this data. The data can be selected by spacecraft, instrument, location, months/years, cloud cover percentage etc.

Data is available from several Landsat satellites but the best data is from Landsat 7; Landsat 5 is also good. This is multispectral data with a resolution of 30 meters/pixel. Here is an experimental and spectacular 12 frame mosaic showing southern Greenland (10% the original size):

Attached Image


The full size version (19000 pixels square) plus additional information can be seen in this blog entry at the Planetary Society website. This image shows a spectacular and complex 'maze' of long and narrow fjords and islands, narrow valleys flanked by steep mountains, glaciers and glacial rivers, countless lakes and ponds and in general a landscape that has been shaped by advancing and retreating glaciers, depending on climate. One important thing to note is that overall this data turned out to be easier to process than is typical for data from other planets.
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Bjorn Jonsson
post Jun 8 2013, 06:15 PM
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Landsat 8 was launched in February. Following a period of checkouts and calibrations it started regular operations in late May. Below is a mosaic of three Landsat 8 images showing a part of northern Iceland. The full size version (12020x18130 pixels) can be downloaded here, the version below is 30% of the original size:

Attached Image


The images were obtained on June 4, 2013 near local noon. The resolution of the full size version is 30 m/pixel. At this time the weather was characterized by strong southerly winds and mountain waves are prominent, especially left of center.

The Landsat 8 image data is of significantly higher quality than earlier Landsat data. In particular, the images are 16 bits which is significant when dealing with high dynamic range scenes where glaciers, snow and clouds are visible together with relatively dark terrain. In this case, the clouds were typically brighter than the dark terrain by a factor of ~5 in the original images . Some areas have relatively fresh snow that is even brighter. The version above has been processed to brighten the dark terrain without losing too much of the detailed structure visible in the clouds.

These images are made available shortly after acquisition, for example I downloaded some images only several hours after they were taken.
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scalbers
post Feb 13 2015, 09:49 PM
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There are some other satellites where color processing can be considered of the land surface and clouds. This includes quite a few spectral bands in DISCOVR - EPIC instrument (near future - as discussed in another thread), VIIRS, and GOES-R ABI (future).

So for the present, we can consider VIIRS polar orbiter also having quite a few spectral bands.

GOES-R ABI will have good rapid update frequency (just minutes) in geosynchronous orbit, though it only has two bands in the visible region with others in the near-IR.

Some other geosynchronous weather satellites (apart from GOES) have or will have multiple visible bands.

Steve


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