Carbon is the basic building block of life, and the carbon cycle represents the cycle of all living organisms. Through the process of photosynthesis, plants on land or algae living in lakes and oceans take up carbon dioxide and convert this into living organic products (such as carbohydrates, proteins, fats, etc.). Through the process of respiration, organisms break down these organic compounds for energy, metabolizing them into various forms of chemical energy and regenerating the carbon dioxide. The level of carbon dioxide in the atmosphere plays an important role in earth's climate through the "greenhouse effect". Therefore, understanding the carbon cycle provides insight about life on earth as well as its role in climate change. The carbon component of interest here is dissolved organic carbon (DOC), which comprises >97% of the organic carbon in the ocean. The dissolved organic carbon in the coastal ocean originates from many sources, including land plant debris and pollution transported by rivers and material excreted from algae and other living organisms in the ocean. Our objective in this study was to quantify DOC from space through the portion of DOC that can be seen by satellite sensorscolored dissolved organic matter (CDOM). The substance that leaches from tea bags is an example of CDOM. Satellite instruments used to study ocean biology do not measure ocean constituents directly, but rather measure light leaving the ocean at multiple wavelengths (blue, green, red, etc.), which can be used to derive the concentration of ocean constituents, including chlorophyll and CDOM. In fact, the presence of high levels of CDOM in coastal waters reduces the accuracy of satellite chlorophyll measurements.We 'conducted multiple expeditionswithin the coastal ocean region along the U.S. MidAtlantic to collect measurements of DOC, CDOM, and light leaving the ocean to develop relationships to compute CDOM and DOC from NASA's MODIS and SeaWiFS satellite sensors. We also evaluated the accuracy of the satellite measurements through comparisons with independent measurements collected at sea. Our results demonstrate that the accuracies of satellite-derived measurements are within 9% for DOC and 20% for CDOM for our coastal ocean study region. These results compare very well with the 33% accuracy for satellite estimates of ocean chlorophyll globally. This study represents the first successful and verified satellite measurements of dissolved organic carbon and colored dissolved organic matter in the coastal ocean. These new satellite products can be applied to study coastal ocean processes such as the export of DOC from land to the ocean, the summer accumulation of DOC from algae and other organisms, and the summer bleaching of CDOM by sunlight. We can apply these satellite observations to investigate interannual and decadal-scale variability in surface ocean CDOM and DOC within coastal waters and monitor impacts of climate change and human activities on coastal ecosystems.https://ntrs.nasa.gov/search.jsp?R=20080040698 2019-03-2...

[1] Although the oceans are a significant source of the greenhouse gas nitrous oxide (N 2 O) to the atmosphere, the magnitude and characteristics of this source are poorly constrained. We present here stable isotope and isotopomer (intramolecular distribution of 15

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Phytoplankton pigments constitute many more compounds than chlorophyll a that can be applied to study phytoplankton diversity, populations, and primary production. In this study, field measurements were applied to develop ocean color satellite algorithms of phytoplankton pigments from in-water radiometry measurements. The match-up comparisons showed that the satellite-derived pigments from our algorithms agree reasonably well (e.g. 30-55% of uncertainty for SeaWiFS and 37-50% for MODIS-Aqua) to field data, with better agreement (e.g. 30-38% of uncertainty for SeaWiFS and 39-44% for MODIS-Aqua) for pigments abundant in diatoms. The seasonal and spatial variations of satellite-derived phytoplankton biomarker pigments, such as fucoxanthin, which is abundant in diatoms, peridinin, which is found only in peridinincontaining dinoflagellates, and zeaxanthin, which is primarily from cyanobacteria in coastal waters, revealed that higher densities of diatoms are more likely to occur on the inner shelf and during winter-spring and obscure other abundant phytoplankton groups. However, relatively higher densities of other phytoplankton, such as dinoflagellates and cyanobacteria, are likely to occur on the mid-to outer-continental shelf and during summer. Seasonal variation of riverine discharge may play an important role in stimulating algal blooms, in particular diatoms, while higher abundances of cyanobacteria coincide with warmer water temperatures and lower nutrient concentrations.