The role of satellite imagery in climate change research, or ICESCAPE

Dr. Kevin Arrigo in Armed with Science, which seems to be a tentacle of the US Department of Defense. Arrigo is a Professor in the Department of Environmental Earth System Science at Stanford and the Chief Scientist for NASA’s ICESCAPE (Impact of Climate change on the Eco-Systems and Chemistry of the Arctic Pacific Environment) mission this summer onboard US Coast Guard Cutter HEALY: …Satellite remote sensing plays two important roles within ICESCAPE. First, by analyzing daily satellite images of everything from sea ice cover to ocean temperature to the concentration of chlorophyll in the water, we can conduct a more efficient sampling program. Want to sample heavy pack ice? Or avoid it? Satellites tell us where to go. Want to collect seawater samples with lots of phytoplankton? Satellites tell us where they are.

The second role played by satellite imagery is a bit different –- it is used to “fill in the blanks” in our field program. Even though ICESCAPE will sample a big chunk of the Chukchi and Beaufort seas, we can’t be everywhere all the time. That would take lots of ships, lots of time, and lots of money. But satellites can tell us what conditions were like before we arrive, after we leave, and in areas we don’t sample. The result? A better understanding of what we are seeing while we are here.

But this is a two-way street. We can help satellite data, too. Robert Frouin (Scripps Institution of Oceanography) is working on ways to extract more information from satellite images when sea ice or high clouds are around. Formerly, satellite pixels (like those tiny dots that make up a picture in your newspaper) that were “contaminated” by clouds or sea ice were discarded or ignored. Not anymore. Frouin’s approach works kind of like those TV shows where the star pushes a button and magically makes a fuzzy picture look sharper. And in a region as cloudy and ice covered as the Arctic, every scrap of information helps!

Finally, field data collected during ICESCAPE by Greg Mitchell (Scripps Institution of Oceanography), Stan Hooker (NASA Goddard Space Flight Center) and Kevin Arrigo (Stanford University) will be used to ensure that satellite data, and the products that are derived from them, are as accurate as they can be (but more about this in later posts)….

This image of Alaska and its ocean environs from June 24, 2010 combines data from different satellites. Brown is land; gray is Arctic sea ice; and the colored areas represent different levels of chlorophyll. Chlorophyll a, the green pigment that aids photosynthesis, is an indicator of the amount of phytoplankton in the ocean. On this image, red illustrates areas of high chlorophyll concentration, where there is a lot of phytoplankton and hence a lot of primary productivity. (Image: Gert van Dijken, Science and Engineering Associate at Stanford University)