By Kyle Turner, Charlotte Rhoads, Maria Tzortziou, Joaquim Goes, and Antonio Mannino<\/strong>\u00a0<\/p>\n In early 2025,\u00a0Maria Tzortziou<\/a>\u00a0and members of her\u00a0lab\u00a0at\u00a0the City College of New York,\u00a0Joaquim Goes from the Goes-Gomes Lab<\/a>\u00a0at Columbia University\u2019s Lamont-Doherty Earth Observatory,\u00a0and\u00a0Antonio Mannino\u00a0from\u00a0NASA\u2019s\u00a0Goddard Space Flight Center<\/a>,\u00a0joined forces with\u00a0OceanX<\/a>\u2014a global nonprofit working to unlock the ocean\u2019s sustainable potential\u2014to collect data\u00a0in\u00a0some of the most under-sampled regions of the ocean.\u00a0\u00a0<\/p>\n The primary goal of our\u00a0collaboration was to\u00a0support and validate\u00a0science data products from\u00a0NASA\u2019s recently launched\u00a0Plankton, Aerosol, Cloud, ocean Ecosystem (PACE)<\/a>\u00a0satellite mission which, as\u00a0the\u00a0name suggests,\u00a0was\u00a0designed to\u00a0provide cutting-edge\u00a0space-based observations\u00a0to\u00a0better\u00a0study\u00a0and monitor the\u00a0processes, properties, and health of Earth\u2019s closely interconnected ocean and atmosphere.\u00a0<\/p>\n Launched in February 2024,\u00a0the\u00a0PACE\u00a0Ocean Color instrument (OCI)\u00a0is the newest,\u00a0most advanced\u00a0polar-orbiting<\/a>\u00a0satellite\u00a0sensor\u00a0monitoring\u00a0ocean color<\/a>,\u00a0an\u00a0essential variable<\/a>\u00a0for\u00a0tracking\u00a0long-term\u00a0global\u00a0climate and ecosystem change.\u00a0\u00a0<\/p>\n The\u00a0PACE\u00a0mission\u00a0builds on a nearly 30-year\u00a0continuous\u00a0data record of space-based ocean color\u00a0observations that have\u00a0revolutionized our\u00a0understanding\u00a0of ocean biology\u00a0and biogeochemistry,\u00a0providing a daily,\u00a0planet-scale\u00a0view of\u00a0phytoplankton<\/a>\u2014microscopic, single-celled, photosynthetic\u00a0organisms\u00a0that\u00a0form\u00a0the foundation of\u00a0aquatic\u00a0food webs.\u00a0\u00a0<\/p>\n Like plants on land, phytoplankton\u00a0use chlorophyll and other pigments to\u00a0absorb sunlight and take in carbon dioxide\u00a0and nutrients\u00a0to\u00a0grow, producing\u00a0oxygen\u00a0as a byproduct.\u00a0While individually microscopic, phytoplankton blooms\u2014large proliferations of cells that can\u00a0span\u00a0hundreds of square kilometers\u00a0or more\u00a0on the ocean surface\u2014color the\u00a0water\u00a0myriad\u00a0hues\u00a0of green, turquoise, red,\u00a0or brown,\u00a0depending on the\u00a0type (or types)\u00a0of\u00a0species composing the bloom.\u00a0<\/p>\n Compared with\u00a0previous\u00a0polar-orbiting\u00a0ocean color\u00a0sensors\u00a0that could measure only a handful of colors, or wavelengths of light, PACE\/OCI\u00a0provides\u00a0hyperspectral\u00a0resolution<\/a>, recording more than\u00a0two\u00a0hundred different wavelengths over the ultraviolet, visible, and near-infrared regions of the electromagnetic spectrum. This improved\u00a0\u201ccolor vision\u201d\u00a0gives scientists unprecedented ability to detect\u00a0different types\u00a0of phytoplankton based on their\u00a0unique\u00a0optical\u00a0signatures, which can advance our\u00a0knowledge of ocean biodiversity, ecosystem dynamics, and the impacts of ongoing ocean warming and acidification, such as harmful algal blooms.\u00a0This new capability to measure \u201call shades of color\u201d in the ocean also allows observations of the quality\u00a0and transformations of organic carbon\u2014the\u00a0fundamental building block of life on our planet.\u00a0<\/p>\n Tzortziou\u00a0and\u00a0Goes\u00a0are members of the\u00a0PACE Validation Science Team (PVST)<\/a>, a comprehensive\u00a0and rigorous\u00a0effort involving many\u00a0research groups\u00a0across the\u00a0globe\u00a0to\u00a0validate\u00a0the data that PACE is\u00a0now\u00a0collecting in\u00a0orbit.\u00a0The main idea: to ensure that measurements from PACE agree\u00a0(within an acceptable\u00a0error)\u00a0with the same measurements taken\u00a0in situ, or from\u00a0the water\u00a0directly,\u00a0via\u00a0ships, buoys,\u00a0or other platforms.\u00a0\u00a0<\/p>\n To\u00a0obtain\u00a0accurate\u00a0data on the color of the ocean\u00a0from PACE,\u00a0the\u00a0light\u00a0absorption and scattering effects of the atmosphere\u00a0must first\u00a0be accounted for\u00a0and removed\u00a0through\u00a0a complex process known as\u00a0atmospheric correction<\/a>.\u00a0Collecting high-quality\u00a0in situ\u00a0validation data is essential to evaluate\u00a0which atmospheric correction\u00a0methods\u00a0work\u00a0best for PACE and how they can be improved.\u00a0<\/p>\n In situ\u00a0<\/em>validation data is also needed\u00a0to\u00a0assess\u00a0the accuracy of algorithms\u00a0applied to PACE data\u00a0and\u00a0map\u00a0an array\u00a0of\u00a0ecological\u00a0products, such as suspended sediments,\u00a0dissolved organic carbon,\u00a0or phytoplankton community composition, which\u00a0can serve to\u00a0advance\u00a0scientific discovery and\u00a0environmental\u00a0monitoring\u00a0and modeling\u00a0capabilities.\u00a0\u00a0<\/p>\n Because the atmosphere and ocean can have very different properties across\u00a0regions (think\u00a0mega-cities\u00a0versus deserts), the objective of the PVST program is to collect\u00a0consistent, high-quality\u00a0data in as many contrasting areas of the\u00a0ocean\u00a0(and\u00a0inland waters<\/a>) as possible, especially regions\u00a0with a relative\u00a0lack\u00a0of\u00a0historical\u00a0observations.\u00a0\u00a0<\/p>\n This\u00a0lack motivated\u00a0Tzortziou\u00a0and Goes to focus their\u00a0PVST\u00a0activities\u00a0on the\u00a0Northern\u00a0Indian Ocean, which is both historically under-sampled and highly dynamic seasonally and inter-annually.\u00a0The team completed a\u00a0successful\u00a0cruise in the\u00a0Bay of Bengal<\/a>\u00a0on the\u00a0R\/V Thomas G. Thompson\u00a0last spring,\u00a0along with a team from Mannino\u2019s NASA oceans field group. Shortly after, an exciting new opportunity\u00a0came along.\u00a0<\/p>\n You may\u00a0have heard of\u00a0OceanX, a non-profit initiative of\u00a0Dalio Philanthropies, through the\u00a0National Geographic TV series<\/a>. \u201cOceanXplorers\u201d (produced by James Cameron) showcased\u00a0the initiative\u2019s exploration of life in the deep ocean, featuring high-tech\u00a0submersibles and remotely operated vehicles (ROVs)\u00a0aboard the\u00a0state-of-the-art\u00a0research and media vessel\u00a0OceanXplorer<\/a>.\u00a0\u00a0<\/p>\n In January of this year,\u00a0OceanX, in collaboration with\u00a0OceanQuest<\/a>, launched the \u201cAround Africa Expedition,\u201d a four-month mission endorsed by the\u00a0United Nations Ocean Decade<\/a>\u00a0framework, to explore deep sea seamount ecosystems, conduct high-resolution seafloor mapping, and engage college students and early career ocean professionals from across the African continent.\u00a0\u00a0<\/p>\n Prior to the start of the expedition, Goes,\u00a0Tzortziou\u00a0and Mannino\u00a0connected with Vincent Pieribone, co-CEO and chief science officer of\u00a0OceanX\u00a0and senior research scientist at Lamont-Doherty Earth Observatory, to talk about the potential of the Around Africa program to contribute to NASA\u2019s PACE validation efforts.\u00a0Fortunately,\u00a0there were still a few berths available on the ship, and the\u00a0exciting\u00a0partnership\u00a0would become a\u00a0reality.\u00a0<\/p>\n On January 27,\u00a0Goes, Mannino,\u00a0and\u00a0NASA ocean ecologist\u00a0Scott Freeman\u00a0boarded for the first leg of the expedition,\u00a0which would\u00a0cover\u00a0over 1,865 miles (3,000 kilometers)\u00a0from the Maldives in the Indian Ocean to Comoros, an island nation off the coast of Madagascar.\u00a0Later in February, Kyle Turner, a\u00a0research\u00a0associate\u00a0in the\u00a0Tzortziou\u00a0Lab,\u00a0and two new members of the NASA\u00a0Ocean Ecology Lab field support group, Harrison Smith and Kelsey Allen,\u00a0boarded\u00a0the\u00a0OceanXplorer\u00a0in Cape Town, South Africa.\u00a0From Cape Town, the\u00a0ship made a four-day trip to Walvis Bay, Namibia, before\u00a0proceeding\u00a0over 18 days\u00a0up\u00a0the majority of Africa\u2019s west coast to Mindelo,\u00a0Cape Verde. Tzortziou, Goes, and Charlotte Rhoads, a master\u2019s student in the\u00a0Tzortziou\u00a0Lab,\u00a0closed out the journey on the\u00a0final\u00a0transit\u00a0from Mindelo to Las Palmas, Gran Canaria.\u00a0<\/p>\n Over the voyage, a\u00a0sophisticated\u00a0arsenal of scientific instruments was deployed\u00a0on the\u00a0OceanXplorer\u00a0to measure the optical and biogeochemical properties needed to\u00a0thoroughly\u00a0validate\u00a0PACE.\u00a0\u00a0<\/p>\n To measure ocean color, multiple\u00a0hyperspectral\u00a0radiometers, detailed light sensors,\u00a0were\u00a0used. One of these sensors,\u00a0a solar tracking system\u00a0called the\u00a0pySAS<\/a>, was installed on the\u00a0helideck\u00a0at the front\u00a0of the\u00a0ship\u00a0to collect\u00a0light radiance data\u00a0from the water, sun,\u00a0and sky\u00a0continuously\u00a0over the cruise\u00a0(when outside of\u00a0non-permitted exclusive economic zones<\/a>).\u00a0An in-water profiling radiometer, or\u00a0HyperPro<\/a>,\u00a0and a handheld\u00a0Spectra Vista Corporation\u00a0(SVC<\/a>)\u00a0radiometer\u00a0were also used to collect\u00a0ocean color\u00a0measurements\u00a0once\u00a0per day, as close as possible to\u00a0the time that PACE would\u00a0be\u00a0doing its daily overpass of the\u00a0ship\u2019s\u00a0location\u00a0(about\u00a01 p.m. local time).\u00a0\u00a0<\/p>\n Coincident with\u00a0the\u00a0radiometric measurements\u00a0and PACE overpass, water\u00a0samples\u00a0were collected\u00a0using the\u00a0OceanXplorer\u2019s\u00a0CTD-rosette (or\u00a0\u201cCarl\u201d as the crew calls it)\u00a0to\u00a0quantify\u00a0the\u00a0materials\u00a0within the water that\u00a0influence\u00a0its\u00a0color. The\u00a0water\u00a0samples were\u00a0specially\u00a0filtered in the\u00a0ship\u2019s\u00a0wet lab\u00a0for analysis of\u00a0chlorophyll-a and other phytoplankton pigments, particulate and dissolved organic\u00a0carbon, and suspended sediment concentrations, among other things. The samples would be\u00a0returned to the U.S.\u00a0and\u00a0processed\u00a0at\u00a0the NASA or university lab facilities.\u00a0<\/p>\n Measurements and water\u00a0collections\u00a0were also\u00a0taken\u00a0from the ship\u2019s seawater flow-through system, which pumped\u00a0surface water through the ship\u00a0continuously as the ship\u00a0was\u00a0underway.\u00a0A suite of optical sensors was connected in-line to measure the inherent light absorption and scattering properties of the\u00a0seawater. Two other\u00a0water flow imaging\u00a0instruments, an Imaging\u00a0FlowCytobot\u00a0(IFCB<\/a>) and\u00a0FlowCam<\/a>,\u00a0recorded high-resolution microscopic images of individual phytoplankton cells, giving the\u00a0scientists a real-time view of how the phytoplankton community composition was shifting as the ship traversed through changing water conditions.\u00a0<\/p>\n \u00a0<\/p>\n \u00a0<\/p>\n This mountain of\u00a0information\u00a0would\u00a0all\u00a0be related back to the light\u00a0data\u00a0recorded by PACE in space, ensuring the highest level of\u00a0data\u00a0accuracy and helping to push the boundaries of the science\u00a0that\u2019s\u00a0possible with\u00a0the\u00a0new technology\u00a0PACE provides.\u00a0<\/p>\n While getting good validation data was the main\u00a0goal, it\u00a0wasn\u2019t\u00a0the only\u00a0positive outcome\u00a0of the collaboration.\u00a0\u00a0<\/p>\n On each leg of the Around Africa Expedition, a new cohort of students\u00a0or early career ocean professionals\u00a0from all over Africa joined for\u00a0the\u00a0unforgettable experience\u00a0of\u00a0sailing and learning aboard the\u00a0OceanXplorer.<\/em>\u00a0Instructors provided hands-on training\u00a0and lectures\u00a0on things such as environmental DNA (eDNA) sequencing, video media and virtual reality,\u00a0international\u00a0ocean policy,\u00a0and ROV piloting.\u00a0<\/p>\n Members of the PVST team also had the chance to teach about\u00a0the basics of\u00a0satellite remote sensing and the\u00a0importance of the NASA PACE mission, both through prepared presentations and in-person demonstrations of the optical instruments, wet lab sampling procedures, and how to find and download PACE imagery.\u00a0<\/p>\n Across\u00a0their varying roles and backgrounds, many members of the cohort expressed an interest in using PACE\u00a0data\u00a0for their work, ranging from fisheries management in Nigeria\u00a0to coral reef conservation in Madagascar\u2014evidence\u00a0that ocean science and\u00a0NASA\u2019s global ocean imagery\u00a0truly have global reach\u00a0for accelerating knowledge and protecting our shared ocean resources.\u00a0<\/p>\nChanging Colors, Changing Seas<\/strong>\u00a0<\/h2>\n
\u201cOcean-truthing\u201d satellite measurements<\/strong>\u00a0<\/h2>\n
Enter\u00a0the\u00a0OceanXplorer<\/strong>\u00a0<\/h2>\n
The tools of\u00a0PACE\u00a0validation<\/strong>\u00a0<\/h2>\n
Inspiring the next\u00a0ocean leaders<\/strong>\u00a0<\/h2>\n
![](\"https:\/\/science.nasa.gov\/wp-content\/themes\/nasa\/assets\/images\/solar-system\/nasa-starfield.webp\"\/)
<\/p>\n