Improvements in satellite and computing technology mean we can collect much more Earth observation data than ever before. Utilizing that data is a challenge weÛªre still working on, however.
There is a potential treasure trove of scientific knowledge in the variety and amount of data collected through remote Earth observation. But the potential is only half the story ÛÒ developing ways to effectively use that data is another challenge.
Jack Kaye of NASA spoke to issues surrounding Earth observation by satellites at the 2015 Annual Meeting of the American Association for the Advancement of Science (AAAS) held in February in San Jose, California.
Kaye, associate director for research in NASAÛªs Earth Science Division, emphasized the variety of data that can be collected from space and the multitude of ways that data can be used to learn more about Earth and its population.
For example, something as simple as comparing the relative intensity of lights at night can be fruitful information for those studying the location and development of populations.
ÛÏNight lights are a great way of thinking about human geography,Û Kaye said. ÛÏYou can look at where people are. The North Korea-South Korea border is very clear, because there are very few night lights in North Korea.Û
Remote observation can be used used to evaluate and quantify the impact that humans are having on the planet. ÛÏYou can see how weÛªve literally changed the face of the Earth,Û Kaye said. ÛÏWithout the point of view of satellites, it would be very, very difficult to have a quantitative sense of what the Earth is doing.Û
According to Kaye, remote observation data becomes an even more powerful tool when multiple data sets are combined. For example, the Aquarius satellite has been taking measurements of sea surface salinity (SSS). But some of the most important information from this mission has come from combining the SSS data with other data sets. ÛÏIf you start combining this (SSS data) with precipitation data, that starts giving you a real window into the weather cycle over the ocean,Û Kaye said. ÛÏYou can start inferring things about evaporation.Û
One of the biggest advantages of remote observation is the ability to observe a variety of environments, including places that may be difficult to reach on the surface, like the middle of the ocean ÛÒ or even underground.
ÛÏWe’re seeing things about our planet that we couldn’t see before,Û Kaye said. ÛÏWe can even look underground (with the) Gravity Recovery and Climate Experiment (GRACE) satellites.Û
Instruments on the GRACE satellites detect subtle variations in EarthÛªs gravitational field. This information can be used to track groundwater, ocean currents, and glacier changes, among other things.
Big data challenges
Hurdles to meaningful Earth observation donÛªt end with getting satellites into the sky and collecting data, as the volume of data collected is so enormous that finding the resources to analyze it is a significant challenge. Melba Crawford, associate dean of engineering for research at Purdue University, said at the AAAS event that each data set presents its own challenges with different combinations of spatial and spectral resolution. Crawford has developed new methods of analyzing this data that extract information by reducing the dimensions of the data.
The big data problem could be further compounded by the addition of crowdsourced data, such as information reported by forest managers, farmers, and other land managers.
ÛÏOne thing people are really excited about is leveraging non-traditional data sources,Û said Crawford, who is a former president of the IEEE Geoscience and Remote Sensing Society. However, this data would be difficult to validate and may not be usable for scientific analysis.
Just developing the tools to analyze data isnÛªt the only requirement to making good use of Earth observation systems. Sharing data among agencies and nations is essential to getting the most out of our Earth observation, according to Kaye.
ÛÏ(The data sets) are made widely available because we believe in an open data policy,Û Kaye said. ÛÏHaving the open data policy is really important, because if our partners are finding things, and we canÛªt get it, it doesnÛªt do us much good.Û
You can find this open data at earthdata.nasa.gov.
Below: The gradual disappearance of Lake Urmia in Iran, 1972-2014. Images from Landsat. Video Credit: NASA’s Goddard Space Flight Center