Landsat at your fingertips

The USGS has put together a slick GUI that let's you browse (as if it were GoogleEarth) and download Landsat data. The interface is described here.

One of my students found this and showed it to me. (Over the next few weeks, hopefully I'll be able to post much of the material and discoveries from my new course "Spatial Data and Analysis".)

Ice loss and satellite measurement

There's a paper in last week's Nature showing new estimates of global glacial ice loss. The work is interesting in its own right (the authors estimate that glacial loss from several areas is lower than prior estimates, although the global total is similar) but I think it's particularly noteworthy for FE readers because it's a nice example of a paper using data from the GRACE satellites. If you don't know of the GRACE twins and need to be reminded of humanity's ability to produce amazing technological advancement, you might want to read this overview from one of the project sites:

As the GRACE-twins fly in formation over the Earth the precise speed of each satellite and the distance between them is constantly communicated via a microwave K-band ranging instrument. As the gravitational field changes beneath the satellites - correlating to changes in mass (topography) of the surface beneath - the orbital motion of each satellite is changed. This change in orbital motion causes the distance between the satellites to expand or contract and can be measured using the K-band instrument. From this, the fluctuations in the Earth's gravitational field can be determined. 

Here's an example of how it works. The two GRACE satellites are traveling in space, both 500 kilometers above the earth. As the front satellite approaches an area of higher gravity, it will be pulled toward the area of higher gravity and speed up. This increases the distance betweenthe two satellites. As the satellites straddle the area of higher gravity, the front satellite will slow down and the trailing satellite will speed up. As the trailing satellite passes the area of higher gravity, it will slow down and the lead satellite will not be affected. As the satellites move around the Earth, the speeding up and slowing down of the satellites will allow scientists to measure the distance between the two satellites, and, therefore, map the earth's gravity field.

A map of the Earth's gravitational field can in turn be used to infer mass changes driven by (for example) melting glaciers, changes in groundwater, or a variety of other phenomena, making GRACE useful for a wide variety of different research topics.

JPL's main site for the project is here, and a (long) list of publications using GRACE data is available here.

Heat

If you're in the continental US this week you've no doubt experienced one of the worst heat waves in a while. It's hitting 100 (Fahrenheit, sorry) in New York today and the same air mass broke records across the country as it slid east. To that end, here are a few explanatory science links to get you through your needlessly hot Friday afternoon:

• An excellent guide to NOAA's heat and humidity satellites
• A great overview of the insanity that was midwest weather this week (that and the previous link via boingboing's Maggie Koerth-Baker)
• Heat and public health from weather.gov
• Wikipedia's great list of historical heat waves
• A peak into the fascinating and contentious economic literature on heat and agricultural yields

Enjoy!

The Satellite Sentinel Project

While reading about the new nation of Southern Sudan, I notice a citation to the Satellite Sentinel Project. I hadn't heard of this project, so I looked it up. It sounds like a great use of modern technology and I'll be interested if it's effective.  [Note to social scientists: evaluating its effectiveness seems like an excellent, albiet difficult, research topic.] From their site:

About the Satellite Sentinel Project 

George Clooney initiated the Satellite Sentinel Project (SSP) while on an October 2010 trip to Southern Sudan with Enough Project Co-founder John Prendergast. SSP combines satellite imagery analysis and field reports with Google's Map Maker technology to deter the resumption of war between North and South Sudan. The project provides an early warning system to deter full-scale civil war between Northern and Southern Sudan and to promote greater accountability for mass atrocities by focusing world attention and generating rapid responses on human rights and human security concerns. 

SSP was launched as a six-month pilot project on December 29, 2010, as the result of an unprecedented collaboration between Not On Our Watch, the Enough Project, Google, the United Nations UNITAR Operational Satellite Applications Programme (UNOSAT), DigitalGlobe, the Harvard Humanitarian Initiative, and Trellon, LLC. UNITAR/UNOSAT's role concluded when the pilot phase ended on June 30, 2011. 

The project works like this: Commercial satellites passing over the border of northern and southern Sudan are able to capture possible threats to civilians, observe the movement of displaced people, detect bombed and razed villages, or note other evidence of pending mass violence. 

Google and Trellon collaborated to design the web platform for the public to easily access the images and reports. Harvard Humanitarian Initiative provides system-wide research and leads the collection, human rights analysis, and corroboration of on-the-ground reports that contextualizes the satellite imagery. The Enough Project contributes field reports, provides policy analysis, and, together with Not On Our Watch, and our Sudan Now partners, puts pressure on policymakers by urging the public to act. DigitalGlobe provides satellite imagery and additional analysis. 

The Satellite Sentinel Project marks the first sustained, public effort to systematically monitor and report on potential hotspots and threats to security along a border, in near real-time (within 24-36 hours), with the aim of heading off humanitarian disaster and human rights crimes before they occur. 

Not On Our Watch -- co-founded by Don Cheadle, George Clooney, Matt Damon, Brad Pitt, David Pressman, and Jerry Weintraub -- has provided seed money to launch the project. 

TRMM Satellite picks up Joplin tornado

Our colleague and occasional guest poster Kyle Meng points out that NASA's TRMM satellite (previously here) passed over the supercell that generated this past weekend's megatornado in Joplin, MO, generating a map of the resultant precipitation. You can find out about it here.

TRMM Satellite Data

Our colleague Amir points us to the great tropical precipitation data coming out of the Tropical Rainfall Measuring Mission Satellite. Lots of (tropical) rainfall and storm data, including for big events like cyclones, going back to 1998.

Also worth checking out, and going up on the student resources page shortly, is their very nice little Q&A on climate and weather, here.