Nicholas Tufillaro

Application of the hyperspectral imager for the coastal ocean to phytoplankton ecology studies in Monterey Bay, CA, USA

As a demonstrator for technologies for the next generation of ocean color sensors, the Hyperspectral Imager for the Coastal Ocean (HICO) provides enhanced spatial and spectral resolution that is required to understand optically complex aquatic environments. In this study we apply HICO, along with satellite remote sensing and in situ observations, to studies of phytoplankton ecology in a dynamic coastal upwelling environment—Monterey Bay, CA, USA. From a spring 2011 study, we examine HICO-detected spatial patterns in phytoplankton optical properties along an environmental gradient defined by upwelling flow patterns and along a temporal gradient of upwelling intensification. From a fall 2011 study, we use HICOs enhanced spatial and spectral resolution to distinguish a small-scale ―red tide‖ bloom, and we examine bloom expansion and its supporting processes using other remote sensing and in situ data. From a spectacular HICO image of the Monterey Bay region acquired during fall of 2012, we present a suite of algorithm results for characterization of phytoplankton, and we examine the strengths, limitations, and distinctions of each algorithm in the context of the enhanced spatial and spectral resolution.

A framework for estimating potential fluid flow from digital imagery

Given image data of a fluid flow, the flow field, , governing the evolution of the system can be estimated using a variational approach to optical flow. Assuming that the flow field governing the advection is the symplectic gradient of a stream function or the gradient of a potential function-both falling under the category of a potential flow-it is natural to re-frame the optical flow problem to reconstruct the stream or potential function directly rather than the components of the flow individually. There are several advantages to this framework. Minimizing a functional based on the stream or potential function rather than based on the components of the flow will ensure that the computed flow is a potential flow. Next, this approach allows a more natural method for imposing scientific priors on the computed flow, via regularization of the optical flow functional. Also, this paradigm shift gives a framework--rather than an algorithm--and can be applied to nearly any existing variational optical flow technique. In this work, we develop the mathematical formulation of the potential optical flow framework and demonstrate the technique on synthetic flows that represent important dynamics for mass transport in fluid flows, as well as a flow generated by a satellite data-verified ocean model of temperature transport.

Evaluating VIIRS Ocean Color Products for West Coast and Hawaiian Waters

Automated match ups allow us to maintain and improve the ocean color products of current satellite instruments MODIS, and since February 2012 the Visible Infrared Imaging Radiometer Suite (VIIRS). As part of the VIIRS mission Ocean Calibration and Validation Team, we have created a web-based automated match up tool that provides access to searchable fields for date, site, and products, and creates matchups between satellites (MODIS, VIIRS), and in-situ measurements (HyperPRO and SeaPRISM). The goal is to evaluate the standard VIIRS ocean color products produced by the IDPS and available through NOAA’s CLASS data system. Comparisons are made with MODIS data for the same location, and VIIRS data processed using the NRL Automated Processing System (APS) used to produce operational products for the Navy. Results are shown for the first year of VIIRS data matching the satellite data with the data from Platform Eureka SeaPRISM off L. A. Harbor in the Southern California Bight, and HyperPRO data from Station ALOHA near Hawaii.

Multislit optimized spectrometer for ocean color remote sensing

The National Research Council’s recommended NASA Geostationary Coastal and Air Pollution Events (GEO-CAPE) science mission’s purpose is to identify “human versus natural sources of aerosols and ozone precursors, track air pollution transport, and study the dynamics of coastal ecosystems, river plumes and tidal fronts.” To achieve these goals two imaging spectrometers are planned, one optimized for atmospheric science and the other for ocean science. The NASA Earth Science Technology Office (ESTO) awarded the Multislit Optimized Spectrometer (MOS) Instrument Incubator Program (IIP) to advance a unique dispersive spectrometer concept in support of the GEO-CAPE ocean science mission. MOS is a spatial multiplexing imaging spectrometer that simultaneously generates hyperspectral data cubes from multiple ground locations enabling a smaller sensor with faster revisit times compared to traditional concepts. This paper outlines the science, motivation, requirements, goals, and status of the MOS program.

HICO On-Orbit Performance and Future Directions

The Hyperspectral Imager for the Coastal Ocean (HICO) is flying on the International Space Station. Here we give a brief overview of HICO on-orbit performance and suggest future directions for imaging the coastal ocean.

Remotely sensing the complexity of rivers and estuaries

The coasts of oceans are rich and complex environments. Over half the world’s population live on the coast or along river systems. Water resources in these regions are used for transportation, waste disposal, fisheries, and industries such as oil and gas production. Unfortunately, it is difficult to study these environments using visible remote sensing techniques. Due to water’s strong absorption of visible light, oceans appear dark relative to land in remotely sensed images. In addition, coastal regions are often spatially and spectrally complex. Several color agents, such as sediments from land runoff and pigments from biological productivity (e.g., plankton blooms), are stirred together by tidal forcing and strong coastal currents in these locations. The Hyperspectral Imager for the Coastal Ocean (HICO) was designed to unravel this complexity and is the first space-borne hyperspectral imaging spectrometer that specifically samples ocean coasts. The system has been operating on the International Space Station since October 2009 and has so far captured over 8000 images. This data can be accessed through the Oregon State University HICO website.1 With HICO, selected coastal regions can be targeted. Measurements with full spectral coverage (88 channels between 400 and 900nm) are made at distance intervals of 92m on the ground.2, 3 We have used this data to study estuaries and coastal rivers in the USA and Asia. The high spatial resolution and continuous spectral sampling of HICO makes it particularly valuable for these studies. A key advantage of HICO data is the continuous spectra obtained for each pixel. These provide the opportunity to develop new water remote-sensing algorithms, beyond band ratios, that are based on the analytical spectroscopy techniques that have Figure 1. Hyperspectral Imager for the Coastal Ocean (HICO) image (a) and remotely sensed spectra (b) from the Elwha River on 10 January 2012 (21:56 GMT). The reflectance (Rrs) spectra (b) for the transect shown (a) display a steep decline from 700–730nm for water with high sediment concentration. This results in a negative extrema of the first derivative of the spectrum around 716nm (c). This peak can be used to track the outflow from the Elwha River into the Strait of Juan de Fuca.

Correction: Ryan, J., et al. Application of the Hyperspectral Imager for the Coastal Ocean to Phytoplankton Ecology Studies in Monterey Bay, CA, USA. Remote Sens. 2014, 6, 1007–1025

Studies of phytoplankton ecology in Monterey Bay, CA, USA, using the Hyperspectral Imager for the Coastal Ocean (HICO) and other satellite remote sensing and in-situ observations, were presented in [1]. [...]

Multislit optimized spectrometer: flight-like environment test results

The NASA ESTO funded Multislit Optimized Spectrometer (MOS) Instrument Incubator Program advances a spatial multiplexing spectrometer for coastal ocean remote sensing from laboratory demonstration to flight-like environment testing. The multiple slit design reduces the required telescope aperture leading to mass and volume reductions over conventional spectrometers when applied to the GEO-CAPE oceans mission. This paper discusses the performance and characterization of the MOS instrument from laboratory and thermal vacuum testing. It also presents the current technology readiness level and possible future applications. Results of an ocean color data product simulation study using flight-like performance data from MOS are also covered. The MOS instrument implementation for GEO-CAPE provides system benefits that may lead to measurable cost savings and reductions in risks while meeting its science objectives.

Multislit optimized spectrometer: fabrication and assembly update

The NASA ESTO funded Multi-slit Optimized Spectrometer (MOS) Instrument Incubator Program will advance a spatial multiplexing spectrometer for coastal ocean remote sensing from lab demonstration to flight like environment testing. Vibration testing to meet the GEVS requirements for a geostationary orbit launch will be performed. The multiple slit design reduces the required telescope aperture leading to mass and volume reductions over conventional spectrometers when applied to the GEO-CAPE oceans mission. The MOS program is entering year 3 of the 3-year program where assembly and test activities will demonstrate the performance of the MOS concept. This paper discusses the instrument design, fabrication and assembly. It outlines the test plan to realize a technology readiness level of 6. Testing focuses on characterizing radiometric impacts of the multiple slit images multiplexed onto a common focal plane, and assesses the resulting uncertainties imparted to the ocean color data products. The MOS instrument implementation for GEO-CAPE provides system benefits that can lead to cost savings and risk reduction while meeting the science objectives of understanding the dynamic coastal ocean environment.

Hyperspectral Imaging of Rivers and Estuaries

The Hyperspectral Imager for the Coastal Ocean (HICO) is the first spaceborne imaging spectrometer designed to sample the coastal ocean. HICO samples selected coastal regions at 92 m ground sample distance with full spectral coverage (88 channels covering 400 to 900 nm) and a high signal-to-noise ratio to resolve the complexity of the coastal ocean. HICO has been operating on the International Space Station since October 2009 and collected over 8000 scenes for more than 50 users. We have been using HICO data to study major rivers and estuaries in the US and Asia. Our results show the advantages of HICO’s additional spectral channels and higher spatial resolution for studying these complex coastal waters. We use these data to suggest requirements for spatial and spectral sampling for future ocean color sensors.