Thursday, October 29, 2015

Mapping Invasive Plant Distributions

Invasive plants (Introduced plants that have negative effects on the environment) can pose serious problems to ecosystems by extirpating native plants and causing changes in plant-animal dynamics. In aquatics systems, invasive plants often alter water chemistry or displace native populations of aquatic animals. It is, therefore, crucial for ecosystem stability to monitor and control the spread of invasion. 

Scientists in Germany (in 2013) developed software that allows the identification of two submerged invasive plants in German lakes (Elodea nuttalli and Najas marina) from an aerial photo. The software uses reflectance of incident light to detect these plants since each plant species reflects light in a specific way based on both physical structure and pigmentation. These particular plants can also be used as indicators of changing ecosystem conditions because they commonly colonize lakes with rising water temperatures. I think this is cool because it not only allows for easier monitoring of invasive plants (compared to a physical survey from a boat!) but also presents data on invasive plant spread in a way that is easy for the general public to understand.

 The photo itself is a false color image of a shoreline of Lake Starnberg in Germany. The density of invasive plants in the shallow areas of the lake was measured based on reflectance of incident light and then illustrated using a  rainbow of colors signifying various degrees of invasion (blue=non-vegetated sediment, green/yellow= sparse vegetation, red=dense vegetation). Notice that the areas of dense vegetation occur farther from the shoreline. This is common in submerged aquatic plants since they are outcompeted by emergent plants in shallow waters.

Tuesday, October 27, 2015

Civil War in Syria

    This image depicts the Tigris River at the border of Syria and Northern Iraq as the civil war in Syria progresses. Based on this ancillary knowledge one could assume the patches of dots are refugees fleeing over the bridge to Iraq. The boxes within the image may be some sort of storage unit, or construction materials for refugee camps. The dispersal of people in the bottom of the picture would suggest that it is the area that is Syria because they are congregating to try and get across the bridge, while the top part is Northern Iraq since there are few people towards the top border of the image indicating that there are no people coming across the bridge that way.

    This image is particularly interesting because it shows the effects of the war on the people who aren't really involved and the process of displacement. The Syrian Civil War is also timely as it has popped up in US and European news feeds due to Russia's recent involvement despite the war starting back in 2011. It is also interesting because of the level of detail in the photo, as the photo covers a small area with great detail. The source website did not say which satellite the photo was taken from, but from the resolution of the image, it could be a more recent iteration of either Landsat or SPOT.

Monday, October 26, 2015

Self-absorbed Earth takes tons of selfies

OK, so maybe the Earth isn't actually self-absorbed or taking selfies, but the humans located on its surface want a blue marble-like picture of the Earth on a daily basis. NASA (the humans) isn't taking just one Earth-selfie a day... they're snapping at least 12 images of the completely sun-lit side of the Earth throughout the course of a day as the Earth rotates.

Selfie! Sequence of natural-color images from Oct. 17, 2015 from the EPIC camera aboard DSCOVR.

The iPhone camera, is located one million miles away (over 4 times the distance from the Earth to the Moon) aboard the Deep Space Climate Observatory (DSCOVR). The overall purpose of the spacecraft is to detect and provide advanced warning of Earth-directed space weather caused by the Sun. In addition, DSCOVR observes Earth in order to measure reflected sunlight and re-emitted radiation from the surface of the Earth. 

The Earth Polychromatic Imaging Camera (EPIC) is a spectroradiometer and images in 10 narrow spectral bands ranging from the near-infrared (0.764 and 0.779 micrometers) through the visible (0.443, 0.552, 0.680, and 0.688 micrometers) and into the ultraviolet (0.317, 0.325, 0.340, and 0.388 micrometers) portion of the electromagnetic spectrum. From the vantage point of EPIC at LaGrange-1 point, NASA has a continuous and simultaneous view of the sun-lit side of the Earth. They are able to obtain images with high temporal (1-day return) and relatively high spatial resolution (24 km after compression) covering half of the Earth's surface in one shot! Previously, this was only achieved by stitching many photos together from satellites orbiting much closer to Earth. 

These images of Earth are extremely useful for climate studies. Scientists can monitor the concentration levels of water vapor, ozone and aerosols in the atmosphere, the amount of UV radiation reaching the Earth's surface, cloud cover and cloud heights, albedo, and the overall energy balance of the Earth system. One exciting benefit for scientists is that the data obtained by EPIC will overlap the data coming from low-Earth and geostationary satellites (e.g. Landsat, MODIS) and can be used for comparison and missing data due to near-Earth satellite return times.

Image of North and South America from October 25, 2015 taken by EPIC camera.

View recent and archived natural-color images of Earth from EPIC here!

Original source:

Additional sources (not already linked to in post): 

Wednesday, October 14, 2015

Fires Day and Night

I had a really hard time determining what was a worthy image for the RSITN blog. I decided to look up "remote sensing in the news" and see what came up. I came across some articles with fires from the summer. This was pretty interesting as at night you can see the fires at night by the glow and the smoke by the day. Pretty neat.

An image of fires during the day and night

The article boasts being seen by space. but we know the technology we have is able to see at night but it makes for a great contrast. The at night part lets the viewer pinpoint the average location of the fires. I'm assuming that that there is a geosynchronous satellite normally used for weather. I like that they decided to get this image. 

Modeling Bearded Capuchin Monkey Habitat

Bearded Capuchin monkeys have recently become a topic of great interest within the scientific community. Found in northeastern Brazil, they have garnered attention due to an odd behavior they exhibit: they use stone tools to get to the meat inside of palm nuts, cracking the casings. Scientists want to research the monkeys further, but are concerned that suitable monkey habitat is rapidly disappearing due to industrial agriculture.

Here’s where remote sensing comes in: a team at the University of Maryland and the University of Georgia observed Capuchins and recorded their activities with GPS, while a multi-spectral satellite image was used to determine land cover/land use. Next, an NDVI was developed and researchers mapped the density of the vegetation in the study area. The team also added factors into the model such as elevation, bare soil, shadow and percentages of green vegetation.

The researchers took all of this information into account and turned it into a habitat model. Red and warmer colors are areas with high habitat suitability, while blue and cooler colors represent lower suitability. By mapping the areas of suitable monkey habitat, researchers are better prepared to protect those habitats that are the largest priority and most used by the monkeys.

Credit: Journal of Applied Remote Sensing doi:10.1117/1.JRS.9.096020 (© the authors)

Flooding in Columbia, SC

Recently there has been a lot of flooding in Columbia, South Carolina. I thought remote sensing could offer a unique opportunity to show how far the flooding had spread.  Although it may be difficult to see the relative depth of the water, it very easy to quickly get an idea of how much area is covered in water via aerial images. After a quick google search it was clear that multiple media outlets had coverage of the flooding which included aerial images. The article below is one example of many articles that used aerial imagery to assist in the coverage of this natural disaster.

The Washington Post in particular had a couple of good examples of what the area looked like both before and during the flooding. The first set of images show farmland in the area near Columbia. Throughout the image it’s clear that the agriculture in the area is going to be hugely effected by the massive amounts of water. The second set of images shows the before and after shots of a local river. What is most striking about these images is the two bridges that span the river. Both are completely wiped out! These images show that remote sensing can be useful in detecting all kinds of damages cause by floods and other natural disasters.

Tuesday, October 13, 2015

Remote Sensing to Combat Weeds

In the NDVI orthomosaic (left), the red area is sandy soil; it produced very little wheat. In the color-enhanced orthomosaic (right), the blue area represents the sandy soil with little growth.
Kristina Polziehn

As we shift from intensive to precision agriculture, we're going to need tools to give us an up-to date view of our crops and fields. The article in question is using UAV (unmanned aerial vehicles) to remotely sense their crop fields for weeds. The maps can show them areas of higher weed density, and can even track the spread of herbicide resistant populations. 

Farmers are in need of maps that show them areas in the field that are stressed from either water damage, pests, lack of nutrients.. etc. and remote sensing can help with these issues as well. 

Remote sensing can also be used to get an even better idea about the distribution of soil types on the landscape so farmers can manage water and nutrients better based on whether the soil is sandy or clay. 

The author also discusses the fact that whether you use a UAV or larger, piloted aircraft, the images produced are significantly more useful than current crop scouting and mapping methods. 

Tuesday, October 6, 2015

Satellite Imagery of California Wildfires

Although this article is a few months old, I came across it while doing research on this summer's wildfires for another class.  This article not only shows true-color images but uses false-color to highlight the area of active burning.  The animation, while somewhat awkward, allows you to utilize the benefits of both color-scales.  In the true-color image the large smoke plume is more visible, while the actual fire is more visible in the false-color image. (Note: We discussed this in lecture today when talking about NDVI v. EVI v. SAVI and this comes up in Lab 4! Even though this isn't about vegetation, the science applies.) 

Also, this article was written as these fires were burning, which shows just how helpful remote sensing can be when time is of importance.  The images were taken and released, and an entire article was written on the very next day.  The images were taken by NASA's Aqua satellite.

Monday, October 5, 2015

Time Lapse - 1984-2012 Saudi Arabia Irrigation

The first thing that came to me when we were given this assignment was Google Earth Engine. They have awesome data, and who doesn't love a good time lapse?

This is a time lapse of Saudi Arabia irrigation development. It uses Landsat imagery over a course of 28 years to show the growth crops and irrigation. This imagery is pretty awesome because on the first frame, there is almost no sign of irrigation or crops; just a barren dessert. As the years progress, the fields start to appear seemingly out of nowhere, dotting the landscape with crop circles. 

This is a great example of showing how humans can change their environment and their effect on that environment. 

I embedded the video so you can see it here, and I'll give you a link to see it at Google Earth Engine too!