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NASA What Color Is the Ocean?

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NASA What Color Is the Ocean? Modeling Phytoplankton Diatoms What Color is the Ocean? 150° W 100° W 50° W 0° 50° E 100° E 150° E The image at right shows a harmful algal bloom in Florida Coupled with ship-based measurements and computer models, The color of an object is actually the color of the light reflected while all other colors satellite data allow scientists to observe and study different are absorbed. Most of the light that is reflected by clear, open ocean water is blue, on July 2, 2016. The bloom was caused by cyanobacteria, characteristics about the ocean and how they have changed 45° N while the red portion of sunlight is quickly absorbed near the surface. Therefore, but not all cyanobacteria blooms are toxic. over time, as well as predict how they might change in the future. very deep water with no reflections off the sea floor appears dark navy blue. Near This false-color image [right], generated using the NASA Ocean Biogeochemical Model, shows the primary production by diatoms, the Bahama Islands however, where the water is clear but also shallow, sunlight a group that tends to be large and contributes heavily to the global 0° is reflected off white sand and coral reefs near the surface, making the water carbon cycle. Primary production reflects the amount of carbon that appear turquoise. Deep, clear, open ocean water appears dark Measuring Ocean Color: At Sea and From Space Credit: NASA is converted using sunlight from carbon dioxide into organic carbon navy blue [top right], while shallow coastal waters through a process called photosynthesis. The organic carbon surrounding islands can appear turquoise due 45° S Scientists can measure ocean color directly—by taking water samples from ships and permanent observation sites— represents the carbon that will be usable by higher trophic levels. There are many places on Earth where water is not deep or clear, and therefore, to the reflection of white sand and coral reefs These data help to improve our understanding of the global ocean not always blue. Suspended particles and dissolved material in water increase on the ocean surface [middle and left]. or indirectly—using Earth-observing satellites that measure the amount of light backscattered and reflected from Earth’s carbon and biogeochemical cycles. the scattering of light and absorb certain wavelengths differently, influencing the Credit: NASA surface at various wavelengths. Unlike patchy ship-based measurements, satellites provide continuous global coverage Credit: Cecile Rousseaux/USRA/NASA 75° S color of the water. For example, phytoplankton are microscopic marine plants that over long timescales. NASA’s Coastal Zone Color Scanner (CZCS) operated from 1978 through 1986, and was the first use chlorophyll and other light-harvesting pigments to carry out photosynthesis. satellite ocean color mission and provided a proof-of-concept despite its limited view. The first dedicated global ocean color 0 1 2 3 4 Chlorophyll is a green pigment that absorbs Smelly algae blooms as thick sensor, Sea-viewing Wide Field-of-view Sensor (SeaWiFS), operated from September 1997 until the end of the mission in x10-3PgC y-1 the red and blue portions of the light spectrum as guacamole closed Atlantic December 2010. Today, NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard the SPECTRAL(petagrams COVERAGEof carbon per year) Aqua satellite (launched in May 2002) and the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National and reflects green light. Ocean water with high beaches, polluted lakes and OCEAN COLOR HERITAGE SENSORS compared with PACE concentrations of phytoplankton can appear Polar-orbiting Partnership (NPP) satellite (launched in October 2011) routinely observe ocean color along with ocean color Spectral Coverage PACE as various shades of green, depending upon rivers, and could even be satellites operated by other countries. CZCS SeaWiFS MODIS VIIRS What (1978-1985) (1997-2010) (2002-)* (2011-) PRODUCTS Ocean Color Heritage Sensors compared with PACE the type and density of the phytoplankton seen from space in summer Absorbing aerosols population. Other types of algae can make 2016. If you wanted to surf or To continue the eighteen-year record of ocean color measurements, VIOLET This graph compares the portions of the electromagnetic spectrum NO MEASUREMENTS ULTRA- Dissolved organics is water appear reddish or deep yellow. Near that the PACE Ocean Color Instrument will observe compared to PRODUCTS NASA plans to launch the Plankton, Aerosol, Cloud, ocean VIOLET go fishing in affected areas, ULTRA- Sediment-laden water (brown and tan) pours previous NASA ocean color sensors. Human eyes are adapted Total pigment or coastal areas, dissolved organic matter, such Ecosystem (PACE) mission in 2022. The Ocean Color Instrument Chlorophyll-a Functional groups into the northern Gulf of Mexico from the you were out of luck. to see a narrow band of this spectrum called visible light. Using Atchafalaya River in this image taken on as decaying plants, can produce a yellow or BEACH (OCI) onboard PACE will provide the most advanced, continuous satellite sensors to detect multiple spectral band combinations, CLOSED Particle sizes the April 7, 2009. brown color. Soil runoff produces a variety of global observations at high-spectral resolution from the ultraviolet scientists can study various aspects of ocean color in ways that Color Credit: NASA yellow, red, brown, and gray colors. (UV) to near infrared (i.e., 350 – 800 nanometers), plus several they cannot from a photograph. Ocean color features, clouds, Physiology and aerosols each leave their signatures in the electromagnetic short-wave infrared (SWIR) bands. PACE’s broad spectral coverage VISIBLE spectrum and scientists can observe and analyze these patterns Atmospheric Pigment Phytoplankton growth depends on the correction / fluorescence will unveil a variety of new products to aid our understanding of the to detect changes. VISIBLE MODIS availability of sunlight and nutrients. When ocean as well as the atmosphere. Over the ocean, UV data will help chlorophyll conditions are favorable, phytoplankton Spectrophotometry is a method to measure how much light a water Find more information at http://pace.gsfc.nasa.gov. flourescence Coastal biology populations can grow at a rate faster sample absorbs by measuring the intensity of light that passes through discriminate between living and non living components of the upper Credit: NASA Atmospheric than they are consumed, a phenomenon the solution. The diagram illustrates how a spectrophotometer works. ocean. Visible wavelengths will be used to identify the composition Atmospheric cyanobacteria diatom dinoflagellate green algae coccolithophore correction correction known as a bloom. Phytoplankton blooms (clear ocean) (clear ocean) Credit: NASA of phytoplankton communities. NEAR NEAR Phytoplankton are the foundation of the aquatic food web, the primary may cover hundreds of square kilometers INFRARED INFRARED producers, feeding everything from microscopic, animal-like zooplankton and are easily visible from space. In Atmospheric 5 nanometer resolution (345 - 885 nm), 26 required multispectral bands Atmospheric Ocean correction correction to multi-ton whales. Small fish and invertebrates also graze on the this image, ocean waters glow peacock (coastal)** (coastal) & Aerosol/cloud plant-like organisms, which are eaten by larger marine animals and so on. green off the northern Namibian coast Can we tell if a bloom is toxic Remote Sensing of Ocean Color 0.025 *MODIS on Terra does not yet provide science-quality ocean data properties INFRARED Cover image: **MODIS/VIIRS short-wave infrared bands are not optimized for oceans 3 bands Like land plants, phytoplankton consume carbon dioxide and produce on November 21, 2010. Phytoplankton SHORT-WAVE 0.02 INFRARED from space? Not yet. Water SHORT-WAVE oxygen during photosynthesis. In fact, phytoplankton created about half blooms often occur along coastlines This true color image of the North Atlantic Ocean was created using data ) Near IR -1 from the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi the oxygen we breathe today. Phytoplankton are extremely diverse, varying where deep, nutrient-rich waters well up from the ocean depths. The light quality managers use ocean r 0.015 (s National Polar-orbiting Partnership satellite collected on April 12, 2015. from photosynthesizing bacteria (cyanobacteria), to plant-like diatoms, to color of this ocean water suggests the calcite plating of coccolithophores is 0.01 Notice the swirling phytoplankton eddies and different color coastal waters armor-plated coccolithophores (drawings not to scale). turning the water milky. color satellite data to decide Rrs associated with runoff from the eastern United States. Credit: NASA Credit: NASA where to take water samples 0.005 Credit: NASA (remote sensing reflectance) to measure for toxins. 0 400 500 600 700 800 900 During photosynthesis, Wavelength (nm) Why is Ocean Color Important? phytoplankton consume carbon dioxide on a Scientists use ocean color data to study: scale comparable to • fundamental questions about phytoplankton land plants. Some of The high spectral resolution of PACE will this carbon is carried blooms, the aquatic food web, and fisheries; to the deep ocean Colored Dissolved enable scientists to distinguish phytoplankton when phytoplankton Organic Matter Phytoplankton • the storage of carbon in the ocean and the role die and sink, and Clear Water types, which will hopefully
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