d. The burn severity map at right was produced with Landsat’s infrared imaging, including a SWIR band that is found on few other satellites. Within the fire perimeter, dark green is non-burned, light blue is low burn severity, yellow is moderate severity, and red is high.
Clouds can be a real headache when it comes to satellite imaging. Thin, almost transparent cirrus clouds are often difficult to spot, leaving scientists scratching their heads when data from pixels beneath them come out slightly skewed.
But Landsat 8 has an answer for that.
The newest spacecraft in the Landsat family – which has been acquiring data since February 2013 – contains a spectral band on its Operational Land Imager (OLI) that identifies the high-altitude clouds that are not otherwise apparent in other bands.
These images show that well. On the left, cirrus formations drift above the landscape. On the other hand, cirrus clouds are difficult to discern in the natural-color composite Landsat 8 image on the right, looking down on Columbia, S.C., and across the border north to Charlotte, N.C.
Scientists are using the cirrus band to flag images that are heavy with cirrus cloud contamination. Landsat’s newest band makes that easy to detect, thus allowing for the most accurate data possible.
Great Salt Lake North Arm Reaches Record Low February 19, 2016
The water level of the north arm of Great Salt Lake, Utah, has reached a record low elevation of 4,191.6 feet, 1 foot below the previous record. Lower snowpack in recent years has lessened the spring runoff flowing into the lake. These Landsat images show the change in water levels between 2011 and 2015.
Great Salt Lake is a closed lake, with no outlet. Since water leaves the lake only through evaporation, it leaves behind its dissolved minerals, making the lake up to 8 times as salty as seawater.
On the right side of these images are evaporation ponds. Water from the north arm is pumped to these ponds. The water evaporates and salt, potassium, and other minerals are extracted.
The lake’s north and south arms are separated by a railroad causeway, the straight line cutting across the images. Limited water circulates between the lake’s north and south arms through the Union Pacific Railroad Causeway breach, but because of the low water levels, the breach is now dry. The result is even saltier water in the north arm.
A USGS article published in late 2015 provides more information about Great Salt Lake.
Measuring Water Use with Landsat February 11, 2016
As drought conditions continue in the western United States, there is more demand for water for irrigation purposes. Increasing population also increases water demand.
Scientists at the USGS Earth Resources Observation and Science (EROS) Center developed a method to use remote sensing data to quantify water use in the Colorado River Basin. Using Landsat and other ancillary data, including Landsat’s thermal infrared data, scientists created the first ever evapotranspiration (ET) map for the entire basin. ET is water that transpires from plants and evaporates from the ground. It can be used as a measure of water usage. Landsat’s 30-meter resolution allows scientists to estimate ET at the field level.
The annual water use map on the left is based on Landsat data collected during 2010. The colors correspond to millimeters (mm) of water lost to the atmosphere through ET. Fields that are green and blue show the highest ET values. Relatively more water has been used on those irrigated fields. Orange hues are areas that have very little ET, such as sparsely vegetated desert. The Landsat 8 image on the right from September 28, 2015, shows many irrigated crop fields just south of Phoenix, Arizona. The image shows the same area as the water use map for comparison.
With the ET map, water managers get information not seen in just the natural color image. This method can be used to create annual water use maps of other regions or even nationwide. Accurate information on water availability and usage is necessary for planning sustainable use of water, particularly in an ar