Image of the day, November 29, 2017

This image shows an application of active sonar remote sensing to map fish populations and habitat. Sonar involves the active emission of sound pulses, which are reflected by objects that have a different density than the surrounding water. In this application, the sound wave is reflected off of the air-filled swim bladder inside the fish (the white arrow in the center of the image points to a school of fish), and the strength of the echo (represented by color) increases with the size of the fish. The arrow on the right points to the seafloor, which also reflects sonar. This application of sonar is commonly used by researchers and commercial fisheries, and also by members of the public in portable fishfinders, which are used by anglers to locate good fishing spots.

https://oceanservice.noaa.gov/facts/fish-sonar.html

Original image from: https://flowergarden.noaa.gov/science/fostersanctuaryscience2011.html

Fishfinders: http://www.anglerwise.com/2010/05/24/using-fish-finder-for-walleye-fishing-sonar-basics/

A Remote Sensing Imagery Search Engine in the Age of the Remote Sensing Boom

For this image, the significance more so lies in the source of the image than the image itself.  It is a snapshot of the power that this new search engine application for aerial and satellite imagery possesses.  This particular photo is a Landsat satellite photo of pivot irrigation fields.  The photo is pulled from the application itself where the user is able filter between aerial or Landsat imagery and either sift through popular search filters such as pivot irrigation or suburbs or input one of their own by selecting their own sample location.  In choosing their own sample location, the user is supplied with a long list of like features throughout the tileset as determined by a likeness/likelihood algorithm.  The application is becoming increasingly important in a day and age when aerial and satellite imagery is constant and flowing.  Currently my supervisor at the State Cartographer's Office is using the application to attempt to find all baseball fields throughout southern Wisconsin that a potential client could market to based on his findings.  This would be tedious by any other means, but with the application he can select a single baseball field in one area and use the accompanying mini map to find all baseball fields in southern Wisconsin based on likeness.  Linked below is an article that gives context to the importance of the application and also a link to an FAQ provided by the lab behind the application's development that provides insight into how the application functions.

Article:  http://www.cbc.ca/news/technology/satellite-imagery-descartes-labs-geovisual-search-planet-1.4013039

FAQ:  https://descarteslabs.com/search-faqs.html

Image of the Day 11/23

This image is of Bardarbunga Volcano is Iceland. This image specifically is of a lava field of this volcano that is active. There is a pool of magma in the right hand side of the image as well. This was taken using the German satellite TerraSAR-X and the image shows an area of 30km x 50km. This image is especially interesting because this specific volcano has was active in November and was on watch for an eruption. I could not find a photo of the most recent volcanic activity and this image is from 2015.

Source: http://www.dlr.de/dlr/en/desktopdefault.aspx/tabid-10460/685_read-11494/#/gallery/16367

Image of the Day 11/21

Landsat Images showing Ice Scours in the Caspian Sea

Image 1: This is a Landsat 8 image of the Caspian sea acquired on April 16^th, 2016. The image clearly shows a strange seabed scouring phenomena in the region of Tyuleni Archipelago (the light colored lines that break up the darker green vegetation visible on the seabed). One thing that makes them curious is that groups of scours are often parallel to each other and appear to be formed by objects traveling in the same direction. The initial cause of these features was confusing to analysts, one possible proposal is that they were human in origin - the result of seafloor trawling. It was not until this image was compared to the second image, taken in January, that the origin of the scours was identified as gouging caused by sea ice starting to break up.

Image 2: A Landsat 8 image that shows the same region in winter. In the northeastern portion of the image the ice is starting to break up and it is possible to see the scour marks which occur behind the leading edge of shrinking ice floes. This occurs because the Caspian sea is very shallow and the sea ice that develops there is relatively warm and thin. This means the ice pieces are easily moved by wind and currents and are often pushed together, causing some of them to tilt, forming structures called “hummocks.” In the shallow water, the “keels” of these hummocks can become wedged in the sediment, causing scouring as the ice bed is moved. Once the ice melts, only the scour marks persist in the spring and summer, creating the pattern seen in the first image. The parallel nature of groups of lines in the first image can be explained by several ice pieces all being dragged along a similar path by the same wind/current.

Flooding Rivers in Cambodia During Wet Season - 11/16/17

This is an image of Cambodia which shows a flooded region between the Mekong River and the Tonlé River. The image was taken by the Japanese satellite, ALOS, on May 5^th, 2015. The Mekong River is one of the best resources of protein/fish for the surrounding communities. The Tonlé River changes the direction of flow depending on the season. During the dry season it flows south, which contains the months of November through May. During the wet season it flows north which contains the months of June through October. During the wet season the river level rises and causes flooding which then forms a large body of water between the two rivers. The flooding helps to increase fishing since the surface area of the Mekong increases by over six times in the process.

Rann of Kutch - Salt Desert Northwest India

This image is from the Sentinel 2A satellite over Northwestern India. The region, known as the Rann of Kutch, is a salt marsh that is flooded during the monsoon season in summer and reverts to aridity in the winter months. The image is false color, presumably NIR, Red, and Green. As such, there is a distinct line between the vegetated grasslands, in red,  on the bottom half of the image and the salt deserts, in white,  on the top half of the image. Most notably the rectilinear pools of blue are the result of different minerals being extracted in the area. Considering that the whitest areas are arid and salty, the more blue there is in the image the more abundant other minerals in that area. The grasslands were formerly fed by the Indus river until its course was altered during an earthquake in the 20th century. As a product of human processes increased drought, overgrazing, and invasive species threaten the stability of the grasslands. 

Image of the day 11/12

This image of the Putorana Plateau in Siberia is taken from the Sentinel-2A satellite.  Putorana Plateau includes the Putransky State Nature Reserve which is 100 km from the Arctic Circle, so there are no humans there.  There is a mountain range, forests, lakes and rivers.  The lakes are frozen for the most part and the mountains are flat-topped ('plume volcanism').  

Image of the Day November 8, 2017

This is an image of the Eyjafjallajokull volcano on the southern coast of Iceland taken on April 17, 2010 by MODIS, three days after the eruption started. I chose this image because there have been several significant earthquakes from another large Icelandic volcano, Bardarbunga, indicating an eruption may happen relatively soon, and Eyjafjallajokull can be used an analog to help predict possible impacts. This eruption disrupted air traffic in Europe for days, and caused glacier melts and flooding. I like this image because at first glance it looks like it may be silt or sediment in water, however you can see the shadow of the ash plume at the volcano, and you realize just how high it is. To help estimate the height of the plume, NASA used their Multi-angle Imaging SpectroRadiometer on board Terra Satellite to create a 3D image. 

Image of the day - 11.02.2017

This is a false-color Sentinel 2A image of southern Mongolia. The image captures part of the Dobi Desert (given by the sandy, rocky, rigid texture and irregular tone to the image), as well as part of the Baga Bogd Mountain Range as emphasized by the texture and depth/vertical depth on the bottom of the image. The vibrant light blue feature at the top of the image (off-center) is the Taatsiin Tsagaan Lake, which gets its “vivid turquoise colour” from high concentrations of salt (in false-color). Since the image is false-color, I would say the band combinations likely include NIR, Red, and Green. Because of this, areas that appear red have a high reflectance in the NIR—these are vegetated locations. These areas include the mountain range, areas near the lake and smaller bodies of water, as well as the area a bit farther south from the lake. Sentinel 2A images like this one are incredibly pertinent and useful in observing changes in vegetation, soil, water, and erosion patterns.

Image of the day 11/1/17

Image of the day 11/1/2017