Wednesday, September 19, 2012

Satellites: Spying on Earth processes

This is a blogpost of mine taken from the Florida Coastal Everglades Blog. I hope this gives you an idea of some of the stories we are interested in posting on the LTER grad student blog. Contributions can be short and sweet, long and informative, or just full of site pictures! Just as long as they are your tales of what it is like to be a scientist. Cheers!

The Everglades covers an area of 734 square miles, which is about half of the size of the state of Rhode Island and about 350,000 football fields. This is a very large area to cover and can become logistically difficult and costly when you are trying to understand the transformations of the Everglades ecosystem with respect to the natural and man-made modifications to the way water moves through the system.  What if there was a way to measure and monitor these changes to the landscape as a whole without even leaving your office?  Oh wait, there is! Satellites!

Satellites have been orbiting the Earth (among other celestial bodies) for the past three decades. And since the release of free images from NASA Earth-oriented satellites like Landsat and MODIS, remote sensing science has taken huge strides to understanding Earth surface processes. More specifically, related to my research in the Everglades, I can use the multi-spectral images to measure water quality (nutrient) and chemistry (salt) changes. Additionally, we can use these images to calculate the amount of water that leaves the surface through evapotranspiration; a combination of evaporation (water that changes from a liquid to a gas from open water bodies or the soil) and transpiration (water that is released to the atmosphere from the process of photosynthesis). Measuring the changes to water quality and evapotranspiration in the Everglades will help us understand the man-made and natural impacts to the environment and to hopefully make better environmentally and hydrologically conscious decisions, both managerially and socially. Taking advantage of the longevity of the satellite program, with 30 plus years of satellite data in storage, we can get a great view of how the landscape of the Everglades has changed through time from a combination of human-related and natural effects.
Though the satellite data helps us see the Glades from Space, we still need to collect field-based data from strategic field sites for calibration and validation purpose. However, that is a topic for another day.
And now time for some artsy, scientific images that were made using Landsat images…
Orginal Landsat 5TM (Band 5, 4, 2)

Evapotranspiration (calculation)

Evapostranpiration (calculation)

albedo (calculation)

Temperature band from Landsat 5 TM

Net radiation (calculation)

Soil heat flux (calculation)

SAVI (calculation)

Chloride concentration in dry season (calculation)

Chloride concentration in wet season (calculation)

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