A tuned ocean color algorithm for the Arctic Ocean: a solution for waters with high CDM content.

The Arctic Ocean (AO) is the most river-influenced ocean. Located at the land-sea interface wherein phytoplankton blooms are common, Arctic coastal waterbodies are among the most affected regions by climate change. Given phytoplankton are critical for energy transfer supporting marine food webs, accurate estimation of chlorophyll a concentration (Chl), which is frequently used as a proxy of phytoplankton biomass, is critical for improving our knowledge of the Arctic marine ecosystem and its response to the ongoing climate change.

Extending aquatic spectral information with the first radiometric IR-B field observations.

Planetary radiometric observations enable remote sensing of biogeochemical parameters to describe spatiotemporal variability in aquatic ecosystems. For approximately the last half century, the science of aquatic radiometry has established a knowledge base using primarily, but not exclusively, visible wavelengths. Scientific subdisciplines supporting aquatic radiometry have evolved hardware, software, and procedures to maximize competency for exploiting visible wavelength information.

Spectrally simplified approach for leveraging legacy geostationary oceanic observations.

The use of multispectral geostationary satellites to study aquatic ecosystems improves the temporal frequency of observations and mitigates cloud obstruction, but no operational capability presently exists for the coastal and inland waters of the United States. The Advanced Baseline Imager (ABI) on the current iteration of the Geostationary Operational Environmental Satellites, termed the Series (GOES-R), however, provides sub-hourly imagery and the opportunity to overcome this deficit and to leverage a large repository of existing GOES-R aquatic observations. The fulfillment of this opportunity is assessed herein using a spectrally simplified, two-channel aquatic algorithm consistent with ABI wave bands to estimate the diffuse attenuation coefficient for photosynthetically available radiation, ().

One- and Two-Band Sensors and Algorithms to Derive (440) from Global Above- and In-Water Optical Observations.

The colored (or chromophoric, depending on the literature) dissolved organic matter (CDOM) spectral absorption coefficient, aCDOM(λ), is a variable of global interest that has broad application in the study of biogeochemical processes. Within the funding for scientific research, there is an overarching trend towards increasing the scale of observations both temporally and spatially, while simultaneously reducing the cost per sample, driving a systemic shift towards autonomous sensors and observations. Legacy aCDOM(λ) measurement techniques can be cost-prohibitive and do not lend themselves toward autonomous systems.

Community composition and photosynthetic physiology of phytoplankton in the western subarctic Pacific near the Kuril Islands with special reference to iron availability.

The western subarctic Pacific (WSP) is known as one of the most productive regions among the world's oceans in spring. However, its oceanic waters are also known as a High Nutrient, Low Chlorophyll (HNLC) region during summer due to low iron (Fe) availability in seawater. Indeed, recent studies have demonstrated that the distribution of Fe in the WSP is complex and heterogeneous.

Pan-Arctic distributions of continental runoff in the Arctic Ocean.

Continental runoff is a major source of freshwater, nutrients and terrigenous material to the Arctic Ocean. As such, it influences water column stratification, light attenuation, surface heating, gas exchange, biological productivity and carbon sequestration. Increasing river discharge and thawing permafrost suggest that the impacts of continental runoff on these processes are changing.

Sources and assumptions for the vicarious calibration of ocean color satellite observations.

Spaceborne ocean color sensors require vicarious calibration to sea-truth data to achieve accurate water-leaving radiance retrievals. The assumed requirements of an in situ data set necessary to achieve accurate vicarious calibration were set forth in a series of papers and reports developed nearly a decade ago, which were embodied in the development and site location of the Marine Optical BuoY (MOBY). Since that time, NASA has successfully used data collected by MOBY as the sole source of sea-truth data for vicarious calibration of the Sea-viewing Wide field-of-view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer instruments.

Platform perturbations in above-water radiometry.

A comparison of above- and in-water spectral measurements in coastal (but predominantly Case-1) conditions has shown that the uncertainty in above-water determinations of water-leaving radiances made from an offshore tower depends on the proximity of the above-water measurement with respect to the side of the platform. For purposes of this study the proximity of the sampling platform is parameterized as the perpendicular distance (denoted x) from the side of the sampling platform to the center of the area on the sea surface observed by the sea-viewing sensor, the so-called surface spot, which is set by the field of view of the radiometer (or the overlapping fields of view of a multiaperture sensor). Two above-water data processing methods were used to create a diagnostic variable (formulated for Case-1 waters only but also applicable to Case-2 conditions over short time scales) to quantify the presence of superstructure reflections.

Above-water radiometry in shallow coastal waters.

Above- and in-water radiometric data were collected from two coastal platforms: a small boat and an oceanographic tower. The above-water data were processed with and without a correction for bidirectional effects (Q02 and S95, respectively). An intercomparison of water-leaving radiances over a wide range of environmental conditions showed (a) total uncertainties across the blue-green domain were to within 4%, (b) a convergence of the Q02 method with the in-water method (average Q02 intercomparisons were to within 4%), and (c) chlorophyll a concentrations derived from Q02 reflectances and the OC4V4 (Ocean Color 4 Version 4) algorithm agreed with independent high-performance liquid-chromatography determinations to within approximately 32%.