Analyzing Satellite Ocean Color Match-Up Protocols Using the Satellite Validation Navy Tool (SAVANT) At MOBY and Two AERONET-OC Sites

The satellite validation navy tool (SAVANT) was developed by the Naval Research Laboratory to help facilitate the assessment of the stability and accuracy of ocean color satellites, using numerous ground truth (in situ) platforms around the globe and support methods for match-up protocols. The effects of varying spatial constraints with permissive and strict protocols on match-up uncertainty are evaluated, in an attempt to establish an optimal satellite ocean color calibration and validation (cal/val) match-up protocol. This allows users to evaluate the accuracy of ocean color sensors compared to specific ground truth sites that provide continuous data. Various match-up constraints may be adjusted, allowing for varied evaluations of their effects on match-up data. The results include the following: (a) the difference between aerosol robotic network ocean color (AERONET-OC) and marine optical Buoy (MOBY) evaluations; (b) the differences across the visible spectrum for various water types; (c) spatial differences and the size of satellite area chosen for comparison; and (d) temporal differences in optically complex water. The match-up uncertainty analysis was performed using Suomi National Polar-orbiting Partnership (SNPP) Visible Infrared Imaging Radiometer Suite (VIIRS) SNPP data at the AERONET-OC sites and the MOBY site. It was found that the more permissive constraint sets allow for a higher number of match-ups and a more comprehensive representation of the conditions, while the restrictive constraints provide better statistical match-ups between in situ and satellite sensors

VARIABILITY IN THE BACKSCATTERING TO SCATTERING AND F/Q RATIOS OBSERVED IN NATURAL WATERS

, examine the spectral variability of the ratio and examine the variability in different water types related to the changes in the Volume Scattering Function (VSF). In addition, we estimate the T*f/Q (Mobley 9 ) term from above-water measurements of remote sensing reflectance (Rrs) coupled with direct measurements of absorption (a) and backscattering (b b ) coefficients. We will examine the spectral dependence of the T*f/Q term and its relationship to the b b /b ratio, which we use as a substitute for the changing VSF. Finally, we will show how the estimated T*f/Q values vary from the commonly used value of 0.051 used for satellite processing

Optical scattering and backscattering by organic and inorganic particulates in U.S. coastal waters

We present the results of a study of optical scattering and backscattering of particulates for three coastal sites that represent a wide range of optical properties that are found in U.S. near-shore waters. The 6000 scattering and backscattering spectra collected for this study can be well approximated by a power-law function of wavelength. The power-law exponent for particulate scattering changes dramatically from site to site (and within each site) compared with particulate backscattering where all the spectra, except possibly the very clearest waters, cluster around a single wavelength power-law exponent of −0.94 . The particulate backscattering-to-scattering ratio (the backscattering ratio) displays a wide range in wavelength dependence. This result is not consistent with scattering models that describe the bulk composition of water as a uniform mix of homogeneous spherical particles with a Junge-like power-law distribution over all particle sizes. Simultaneous particulate organic matter (POM) and particulate inorganic matter (PIM) measurements are available for some of our optical measurements, and site-averaged POM and PIM mass-specific cross sections for scattering and backscattering can be derived. Cross sections for organic and inorganic material differ at each site, and the relative contribution of organic and inorganic material to scattering and backscattering depends differently at each site on the relative amount of material that is present

Dedicated JPSS VIIRS Ocean Color Calibration/Validation Cruise

The NOAA/STAR ocean color team is focused on “end-to-end” production of high quality satellite ocean color products. In situ validation of satellite data is essential to produce the high quality, “fit for purpose” remotely sensed ocean color products that are required and expected by all NOAA line offices, as well as by external (both applied and research) users. In addition to serving the needs of its diverse users within the U.S., NOAA has an ever increasing role in supporting the international ocean color community and is actively engaged in the International Ocean-Colour Coordinating Group (IOCCG). The IOCCG, along with the Committee on Earth Observation Satellites (CEOS) Ocean Colour Radiometry Virtual Constellation (OCR-VC), is developing the International Network for Sensor Inter-comparison and Uncertainty assessment for Ocean Color Radiometry (INSITU-OCR). The INSITU-OCR has identified, amongst other issues, the crucial need for sustained in situ observations for product validation, with longterm measurement programs established and maintained beyond any individual mission. Recently, the NOAA/STAR Ocean Color Team has been making in situ validation measurements continually since the launch in fall 2011 of the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polar-orbiting Partnership (SNPP) platform, part of the U.S. Joint Polar Satellite System (JPSS) program. NOAA ship time for the purpose of ocean color validation, however, had never been allocated until the cruise described herein. As the institutional lead for this cruise, NOAA/STAR invited external collaborators based on scientific objectives and existing institutional collaborations. The invited collaborators are all acknowledged professionals in the ocean color remote sensing community. Most of the cruise principal investigators (PIs) are also PIs of the VIIRS Ocean Color Calibration and Validation (Cal/Val) team, including groups from Stennis Space Center/Naval Research Laboratory (SSC/NRL) and the University of Southern Mississippi (USM); City College of New York (CCNY); University of Massachusetts Boston (UMB); University of South Florida (USF); University of Miami (U. Miami); and, the National Institute of Standards and Technology (NIST). These Cal/Val PIs participated directly, sent qualified researchers from their labs/groups, or else contributed specific instruments or equipment. Some of the cruise PIs are not part of the NOAA VIIRS Ocean Color Cal/Val team but were chosen to complement and augment the strengths of the Cal/Val team participants. Outside investigator groups included NASA Goddard Space Flight Center (NASA/GSFC), Lamont-Doherty Earth Observatory at Columbia University (LDEO), and the Joint Research Centre of the European Commission (JRC). This report documents the November 2014 cruise off the U.S. East Coast aboard the NOAA Ship Nancy Foster. This cruise was the first dedicated ocean color validation cruise to be supported by the NOAA Office of Marine and Air Operations (OMAO). A second OMAO-supported cruise aboard the Nancy Foster is being planned for late 2015. We at NOAA/STAR are looking forward to continuing dedicated ocean color validation cruises, supported by OMAO on NOAA vessels, on an annual basis in support of JPSS VIIRS on SNPP, J-1, J-2 and other forthcoming satellite ocean color missions from the U.S as well as other countries. We also look forward to working with the U.S. and the international ocean community for improving our understanding of global ocean optical, biological, and biogeochemical properties.JRC.H.1-Water Resource

Coupling Ocean Models and Satellite Derived Optical Fields To Estimate LIDAR Penetration and Detection Performance

A global-scale climatological assessment of the temporal and spatial relationships between physical and optical ocean layers was previously performed to determine LIDAR efficiency for measuring the 3D Ocean. That effort provided estimates of laser sensor penetration depth (PD) in the global oceans and identified critical coupling between Mixed Layer Depth (MLD) and Optical Depth (OD) based on potential laser power and ensuing attenuation. We make use of a Bio-Physical ocean model configured for the Gulf of Mexico (GOM) along with remotely sensed satellite measurements to examine LIDAR performance in the Gulf of Mexico coastal regions. The 4Km GOM ocean model runs in near-realtime and produces physical and bio-optical fields which are coupled to in-house derived satellite bio-optical products such as the Diffuse Attenuation Coefficient at 490 nm (Kd490). PD and MLD are coupled to determine laser power efficiency rates across multiple attenuation lengths. The results illustrate the potential utilization of space-borne oceanographic LIDAR to penetrate through the water column, elucidating its applicability for a variety of scientific (characterization of the ocean subsurface layers) and applied (target detection) objectives. © 2012 SPIE

Seasonal Trends of Biophysical Ocean Properties and Anomalies Across the Mississippi Shelf

© 2018 SPIE. The seasonal cycle in surface biological, optical and physical properties across the river dominated Mississippi (MS) Shelf changed during years 2015 to 2017 at different locations across the shelf. VIIRS satellite and ocean model products were used to monitor cycles for different properties of both the nowcast and anomalous water properties. MS Shelf water properties vary spatially between offshore waters and coastal MS Sound waters, as well as temporally throughout the year. Ten selected regions spanning east to west from the MS Sound to the shelf break characterized the cross shelf seasonal fluctuations in satellite-derived chlorophyll-a, backscattering, euphotic depth, sea surface temperature, and modeled salinity currents. The seasonal relationships between physical and bio-optical properties were determined for different regions across the shelf and the seasonal eastward movement of the MS river plume across the shelf was identified in June. Yearly MS Sound seasonal cycles of coastal bio-physical properties are different from the shelf regions\u27 offshore seasonal cycles and indicate a time-lag between the bio-optical responses to the physical properties. Bio-optical and physical results on the shelf indicated seasonal movements of the MS River plume locations. Results show the seasonal bio-physical response of the shelf waters which can be used to address and understand the timing of data collection and how ocean events are influenced by the natural seasonal cycle interactions between biological and physical properties. The seasonal cycle study will enable the ability to monitor the shelf water quality and to identify non-typical conditions and the impact of an event on the cycle. Correlations between the monthly seasonal cycle of bio-optical and physical properties such as salinity, ocean color, chlorophyll-a and particle scattering were not consistent over the shelf. Seasonal cycles of salinity and chlorophyll-a show improved correlation if chlorophyll-a is delayed one month from the salinity at offshore locations on the shelf. Results of the seasonal trends support how data collected at a single image location on the shelf during a certain month can be different from other seasons. The seasonal cycle of the dynamic anomaly properties (DAP) of bio-physical properties were determined to show how seasonal abnormal changes and trends at locations across the shelf can provide a method for seasonal adaptive sampling. The yearly differences in monthly cycles from 2015 to 2017 at shelf locations, identified elevated chlorophyll-a in several months of 2016 and yearly temperature differences in multiple areas. The seasonal cycle of Euphotic depth, solar UV light penetration, showed a maximum peak (deeper Euphotic depth) at certain shelf locations during the months of September and October and minimal penetration in Aug of 20152016,2017. This information could be useful to understand months for maximum oil UV degradation in case of an oil spill

Estimating Sea Surface Salinity In Coastal Waters of the Gulf of Mexico Using Visible Channels On SNPP-VIIRS

Sea surface salinity is determined using the visible channels from the Visual Infrared Imaging Radiometer Suite (VIIRS) to derive regional algorithms for the Gulf of Mexico by normalizing to seasonal river discharge. The dilution of river discharge with open ocean waters and the surface salinity is estimated by tracking the surface spectral signature. The water leaving radiances derived from atmospherically-corrected and calibrated 750-m resolution visible M-bands (410, 443, 486, 551, 671 nm) are applied to bio-optical algorithms and subsequent multivariate statistical methods to derive regional empirical relationships between satellite radiances and surface salinity measurements. Although radiance to salinity is linked to CDOM dilution, we explored alternative statistical relationships to account for starting conditions. In situ measurements are obtained from several moorings spread across the Mississippi Sound and Mobile Bay, with a salinity range of 0.1-33. Data were collected over all seasons in the year 2013 in order to assess inter-Annual variability. The seasonal spectral signatures at the river mouth were used to track the fresh water end members and used to develop a seasonal slope and bias between salinity and radiance. Results show an increased spatial resolution for remote detection of coastal sea surface salinity from space, compared to the Aquarius Microwave salinity. Characterizing the coastal surface salinity has a significant impact on the physical circulation which affects the coastal ecosystems. Results identify locations and dissipation of the river plumes and can provide direct data for assimilation into physical circulation models. © 2014 SPIE

Enhanced Satellite Remote Sensing of Coastal Waters Using Spatially Improved Bio-Optical Products From SNPP-VIIRS

The spatial dynamics of coastal and inland regions are highly variable and monitoring these waters with ocean color remote sensors requires increased spatial resolution capabilities. A procedure for the spatial enhancement of ocean color products, including chlorophyll and inherent optical properties (IOPs), is developed using a sharpened visible water-leaving radiance spectrum for the visible infrared imaging radiometer suite (VIIRS). A new approach for spectral sharpening is developed by utilizing the spatial covariance of the spectral bands for sharpening the M bands (412, 443, 486, 551, 671. nm; 750-m resolution) with the I-1 band (645. nm; 375-m resolution). The spectral shape remains consistent by the use of a dynamic, wavelength-specific spatial resolution ratio that is weighted as a function of the relationship between proximate I- and M-band variance at each pixel. A comparison of bio-optical satellite products at 375-m and 750-m spatial resolution with in situ measurements of water leaving radiance and bio-optical properties show an improved capability of the VIIRS 375-m products in turbid and optically complex waters, such as the Chesapeake Bay and Mississippi River Plume. We demonstrate that the increased spatial resolution improves the ability for VIIRS to characterize bio-optical properties in coastal waters

Improved Monitoring of Bio-Optical Processes In Coastal and Inland Waters Using High Spatial Resolution Channels On SNPP-VIIRS Sensor

The dynamic and small-scale spatial variability of bio-optical processes that occurs in coastal regions and inland waters requires high resolution satellite ocean color feature detection. The Visual Infrared Imaging Radiometer Suite (VIIRS) currently utilizes five ocean color M-bands (410,443,486,551,671 nm) and two atmospheric correction M-bands in the cnear infrared (NIR; 745,862 nm) to produce ocean color products at a resolution of 750-m. VIIRS also has several high resolution (375-m) Imaging (I)-bands, including two bands centered at 640 nm and 865 nm. In this study, a spatially improved ocean color product is demonstrated by combining the 750-meter (M- channels) with the 375-m (I1-channel) to produce an image at a pseudo-resolution of 375-m. The new approach applies a dynamic wavelength-specific spatial ratio that is weighted as a function of the relationship between proximate I- and M-band variance at each pixel. This technique reduces sharpening artifacts by incorporating the native variability of the M-bands. In addition, this work examines the viability of replacing the M7-band (862 nm) with the I2-band (865 nm) to determine the atmospheric correction and aerosol optical depth at a higher resolution. These true (I-band) and pseudo (M-band) high resolution radiance values can subsequently be utilized as input parameters into various algorithms to yield high resolution optical products. The results show new capability for the VIIRS sensor for monitoring bio-optical processes in coastal waters. © 2013 SPIE

Atmospheric Correction and Vicarious Calibration of Oceansat-1 Ocean Color Monitor (OCM) Data in Coastal Case 2 Waters

The Ocean Color Monitor (OCM) provides radiance measurements in eight visible and near-infrared bands, similar to the Sea-viewing Wide Field-of-View Sensor (SeaWiFS) but with higher spatial resolution. For small- to moderate-sized coastal lakes and estuaries, where the 1 × 1 km spatial resolution of SeaWiFS is inadequate, the OCM provides a good alternative because of its higher spatial resolution (240 × 360 m) and an exact repeat coverage of every two days. This paper describes a detailed step-by-step atmospheric correction procedure for OCM data applicable to coastal Case 2 waters. This development was necessary as accurate results could not be obtained for our Case 2 water study area in coastal Louisiana with OCM data by using existing atmospheric correction software packages. In addition, since OCM-retrieved radiances were abnormally low in the blue wavelength region, a vicarious calibration procedure was developed. The results of our combined vicarious calibration and atmospheric correction procedure for OCM data were compared with the results from the SeaWiFS Data Analysis System (SeaDAS) software package outputs for SeaWiFS and OCM data. For Case 1 waters, our results matched closely with SeaDAS results. For Case 2 waters, our results demonstrated closure with <em>in situ</em> radiometric measurements, while SeaDAS produced negative normalized water leaving radiance (<em><sub>n</sub>L<sub>w</sub></em>) and remote sensing reflectance (<em>R<sub>rs</sub></em>). In summary, our procedure resulted in valid <em><sub>n</sub>L<sub>w</sub></em> and <em>R<sub>rs</sub></em> values for Case 2 waters using OCM data, providing a reliable method for retrieving useful <em><sub>n</sub>L<sub>w</sub></em> and <em>R<sub>rs</sub></em> values which can be used to develop ocean color algorithms for in-water substances (e.g., pigments, suspended sediments, chromophoric dissolved organic matter, <em>etc</em>.) at relatively high spatial resolution in regions where other software packages and sensors such as SeaWiFS and Moderate Resolution Imaging Spectrometer (MODIS) have proven unsuccessful. The method described here can be applied to other sensors such as OCM-2 or other Case 2 water areas