What color is the sea? If you ask a child, they'll likely say that it's blue without batting an eye. If you ask an adult, some will maintain that same response. Many others will say that it’s transparent and that kids think it's blue because of the sky’s reflection and the absorption and scattering of light. To make the question even more complicated, NASA recently shared the first images from its PACE satellite, which show us that the oceans on our planet are not all the same color.
At the eastern end of the Mediterranean, the terrain is varied. The Nile Delta (lower left) stands out with its green color in the Egyptian desert. There are also patches of green along the coasts of Israel, Lebanon, and Syria. The island of Cyprus, south of Turkey, is in the center of the image.
Color depends on many factors. NASA took these photos hundreds of miles from Earth to demonstrate what’s happening on the planet through an environmental lens. These images aren't just regular snaps of the ocean, but rather images taken by measuring infrared wavelengths of light reflected by the ocean. The reflected light features colors not perceptible to the human eye.
Phytoplankton bloom in the Gulf of Oman observed from space.
Another example is the Arctic, where thawing permafrost and the flow of carbon-rich water are causing part of the ocean to emit more carbon dioxide than it absorbs. Even color can vary simply because of depth, which causes light to strike the ocean floor in a completely different way. In other cases, you can see how the blue hue disappears due to processes like eutrophication, which refers to the proliferation of algae and oxygen depletion in water.
Located in the far east of Russia, the Kamchatka Peninsula covers an area roughly the size of Colorado, with more than 100 volcanoes stretching across a 621-mile-long landmass.
PACE aims to measure the health of the planet. In early February, NASA launched the PACE (Plankton, Aerosol, Cloud, Ocean Ecosystem) satellite as part of a mission to provide all kinds of measurements related to climate, air quality, and the way light reflects off ocean waters.
Both images include Japan’s second-largest island, Hokkaido, and Sakhalin, a Russian island. On the left is the real color image. On the right is the shortwave infrared shot, which shows reflected light in colors not visible to the human eye.
As such, the satellite is a valuable first step for scientists. It allows them to obtain data faster, providing a global assessment of the composition of various aerosol particles in the atmosphere. This information will, in turn, provide much needed information on the role of aerosol particles in rising temperatures, among others. Importantly, with PACE's first images, we're getting an accurate visual of the oceans from Earth’s orbit.
The snow-capped Verkhoyansk Mountains and meandering rivers provide stark visual contrasts in this image taken in a remote region of Siberia.
The ocean and climate change. As you can see in the images, satellite data will allow us to study microscopic life in the ocean and particles in the air. This way, we can better understand issues such as the health of fisheries, harmful algal blooms, air pollution, and smoke from forest fires. It will also help us study how the ocean and atmosphere interact and are affected by climate change.
In this image, ice clouds and snow are purple, liquid clouds are pink, water is black, barren ground is brown, and vegetated areas are deep red (e.g., top right).
Behold the ocean like never before. Researchers can observe the ocean, the ground, and the atmosphere through the ultraviolet, visible, and near-infrared light spectrum of the satellite’s Ocean Color Instrument. While previous color satellites could only detect a handful of wavelengths in the water, PACE detects more than 200 wavelengths.
PACE processes the colors in this image to enhance the green tones of the ocean. Why do we care about the green in the oceans? Because they’re a valuable sign of productivity in the ocean ecosystem and an indicator of the health of these bodies of saltwater.
In fact, with this broad spectral range, researchers can identify specific phytoplankton communities, which is one of the satellite's key missions. These communities are important because distinct species play separate roles in the ecosystem and the carbon cycle and in some cases are even harmful to human health.
Image | NASA (PACE)