Dariusz Stramski's research while affiliated with University of California, San Diego and other places
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Publications (149)
Radiative transfer (RT) simulations have long been used to study the relationships between the inherent optical properties (IOPs) of seawater and light fields within and leaving the ocean, from which ocean apparent optical properties (AOPs) can be calculated. For example, inverse models used to estimate IOPs from ocean color radiometric measurement...
Extending the capabilities of optical remote sensing and inverse optical algorithms, which have been commonly focused on the visible (VIS) range of the electromagnetic spectrum, to derive the optical properties of seawater in the ultraviolet (UV) range is important to advancing the understanding of various optical, biological, and photochemical pro...
Radiative transfer (RT) simulations have long been used to study relationships between the inherent optical properties (IOPs) of seawater and light fields within and leaving the ocean from which the ocean apparent optical properties (AOPs) can be calculated. For example, inverse models to estimate IOPs from ocean color radiometric measurements have...
The ocean plays a central role in modulating the Earth’s carbon cycle. Monitoring how the ocean carbon cycle is changing is fundamental to managing climate change. Satellite remote sensing is currently our best tool for viewing the ocean surface globally and systematically, at high spatial and temporal resolutions, and the past few decades have see...
Global observations of ocean color from space provide a unique capability to conduct multi-decadal studies of biogeochemical constituents and processes in the upper ocean layers at the regional, basin, and global scales. The concentration of particulate organic carbon (POC) in the surface ocean waters is one of the biogeochemically important data p...
High complexity and variability in composition of water constituents pose major challenges for development of algorithms to estimate biogeochemical data products from optical observations over the continuum of diverse aquatic environments. To address these challenges, we examined an adaptive optical approach that accounts for variability in composi...
Accurate estimates of the oceanic particulate organic carbon concentration (POC) from optical measurements have remained challenging because interactions between light and natural assemblages of marine particles are complex, depending on particle concentration, composition, and size distribution. In particular, the applicability of a single relatio...
As the concentration of particulate organic carbon (POC) in the surface ocean plays a key role in marine biogeochemical cycles and ecosystems, its assessment from satellite observations of the global ocean is of significant interest. To achieve a global multi-decadal data record of POC by merging observations from multiple satellite ocean color mis...
Plain Language Summary
The particle size distribution (PSD) describes how the concentration of particles changes with particle size, and it is an important characteristic of suspended oceanic particles that influences ocean ecology and biogeochemistry. We analyze an extensive set of measurements of the PSD from the Pacific, Atlantic, and Arctic Oce...
Optical proxies based on light scattering measurements have potential to improve the study and monitoring of aquatic environments. In this study, we evaluated several optical proxies for characterization of particle mass concentration, composition, and size distribution of suspended particulate matter from two contrasting coastal marine environment...
Accurate measurements of absorption data are required for the development and validation of inversion algorithms for upcoming hyperspectral ocean color imaging sensors, such as the NASA Phytoplankton, Aerosol, Cloud, and ocean Ecosystem mission. This study aims to provide uncertainty estimates associated with leading approaches to measure hyperspec...
The MALINA oceanographic campaign was conducted during summer 2009 to investigate the carbon stocks and the processes controlling the carbon fluxes in the Mackenzie River estuary and the Beaufort Sea. During the campaign, an extensive suite of physical, chemical and biological variables were measured across seven shelf–basin transects (south–north)...
The MALINA oceanographic campaign was conducted during summer 2009 to investigate the carbon stocks and the processes controlling the carbon Fluxes in the Mackenzie River estuary and the Beaufort Sea. During the campaign, an extensive suite of physical, chemical and biological variables was measured across seven shelf–basin transects (south-north)...
This publisher's note corrects an equation in Appl. Opt.59, 8314 (2020)APOPAI0003-693510.1364/AO.396709.
Polarized light scattering measurements have the potential to provide improved characterization of natural particle assemblages in terms of particle size and composition. However, few studies have investigated this possibility for natural assemblages of marine particles. In this study, seawater samples representing contrasting assemblages of partic...
The size distribution of suspended particles influences several processes in aquatic ecosystems, including light propagation, trophic interactions, and biogeochemical cycling. The shape of the particle size distribution (PSD) is commonly modeled as a single-slope power law in oceanographic studies, which can be used to further estimate the relative...
Light emerging from natural water bodies and measured by
radiometers contains information about the local type and concentrations of
phytoplankton, non-algal particles and colored dissolved organic matter in
the underlying waters. An increase in spectral resolution in forthcoming
satellite and airborne remote sensing missions is expected to lead to...
Measurements of the particulate volume scattering function, βp(ψ), at light wavelength of 532 nm, particle size distribution, PSD, and several metrics of particulate concentration and composition were made on eight contrasting seawater samples from nearshore and coastal oceanic environments including river estuary and offshore locations. Both βp(ψ)...
Light emerging from natural water bodies and measured by remote sensing radiometers contains information about the local type and concentrations of phytoplankton, non-algal particles and colored dissolved organic matter in the underlying waters. An increase in spectral resolution in forthcoming satellite and airborne remote sensing missions is expe...
Supplement to: Casey, KA et al. 2019: A global compilation of in situ aquatic high spectral resolution inherent and apparent optical property data for remote sensing applications. Earth System Science Data Discussions https://doi.org/10.5194/essd-2019-105
Light emerging from natural water bodies and measured by remote sensing radiometers contains...
We evaluated the performance of a recently developed absorption partitioning model [J. Geophys. Res. Oceans120, 2601 (2015)JGRCEY0148-022710.1002/2014JC010604] that derives the spectral absorption coefficients of non-algal particles, aNAP(λ), and colored dissolved organic matter, ag(λ), from the total absorption coefficient of seawater. The model’s...
An extensive data set of measurements within the Chukchi and Beaufort Seas is used to characterize the optical properties of seawater associated with different phytoplankton communities. Hierarchical cluster analysis of diagnostic pigment concentrations partitioned stations into four distinct surface phytoplankton communities based on taxonomic com...
The particulate beam attenuation coefficient at 660 nm, cp(660), was measured in conjunction with properties of suspended particle assemblages in August 2009 within the Canadian Beaufort Sea continental margin, a region heavily influenced by freshwater and sediment discharge from the Mackenzie River, but also by sea ice melt. The mass concentration...
We measured the linearly polarized light scattering of pure water and seawater at various salinities and estimated the depolarization ratio using five different methods of data analysis after removing the scattering due to contamination by residual nanoparticles. The depolarization ratio values (δ) estimated for pure water using these different met...
The light scattering properties of seawater play important roles in radiative transfer in the ocean and optically-based methods for characterizing marine suspended particles from in situ and remote sensing measurements. The recently commercialized LISST-VSF instrument is capable of providing in situ or laboratory measurements of the volume scatteri...
Although the light fields and apparent optical properties (AOPs) within the ocean euphotic layer have been studied for many decades through extensive measurements and theoretical modeling, there is virtually a lack of simultaneous high spectral resolution measurements of plane and scalar downwelling and upwelling irradiances (the so-called irradian...
Protocols for measuring particulate absorption on filter pads in a spectrophotometer. Comparison of transmission mode, center-mounted integrating sphere, and transmission-reflectance mode, including uncertainty budget.
Chapter 5: Spectrophotometric measurements of particulate absorption using filter pads.
IOCCG Protocol Series (2018). Inherent Optical Property Measurements and Protocols:
Absorption Coefficient, Neeley, A. R. and Mannino, A. (eds.), IOCCG Ocean Optics and
Biogeochemistry Protocols for Satellite Ocean Colour Sensor Validation, Volume 1.0,
IOCCG, D...
An empirical algorithm for estimating particulate organic carbon (POC) concentration in the surface ocean from satellite observations is formulated and validated using in situ POC data and remote-sensing reflectance (Rrs) data obtained from match-up satellite ocean color measurements. The algorithm builds upon the band-difference algorithm concept,...
The particulate beam attenuation coefficient at 660 nm, cp(660), was measured in conjunction with properties of suspended particle assemblages in August 2009 within the Canadian Beaufort Sea continental margin, a region heavily influenced by sediment discharge from the Mackenzie River. The suspended particulate matter mass concentration (SPM) range...
We present an inverse model (referred to as LS2) for estimating the inherent optical properties (IOPs) of seawater, specifically the spectral absorption, a(λ), and backscattering, bb(λ), coefficients within the ocean surface layer, from measurements of ocean remote-sensing reflectance, Rrs(λ). The non-water absorption, anw(λ), and particulate backs...
Ocean color measured from satellites provides daily global, synoptic views of spectral water-leaving reflectances that can be used to generate estimates of marine inherent optical properties (IOPs). These reflectances, namely the ratio of spectral upwelled radiances to spectral downwelled irradiances, describe the light exiting a water mass that de...
Particulate Organic Carbon (POC) plays a vital role in the ocean carbon cycle. Though relatively small compared with other carbon pools, the POC pool is responsible for large fluxes and is linked to many important ocean biogeochemical processes. The satellite ocean-colour signal is influenced by particle composition, size, and concentration and pro...
Extrapolation of near-surface underwater measurements is the most common method to estimate the water-leaving spectral radiance, Lw(
λ) (where λ is the light wavelength in vacuum), and remote-sensing reflectance, Rrs(
λ), for validation and vicarious calibration of satellite sensors, as well as for ocean color algorithm development. However, unce...
The magnitude and spectral shape of the optical backscattering coefficient of particles, bbp(λ), is being increasingly used to infer information about the particles present in seawater. Relationships between bbp and particle properties in the Arctic are poorly documented, and may differ from other oceanic regions which contribute the majority of da...
We develop an optical classification of marine particle assemblages from an extensive dataset of particle optical properties collected in the Chukchi and Beaufort Seas. Hierarchical cluster analysis of the spectral particulate backscattering-to-absorption ratio partitioned the dataset into seven optically-distinct clusters of particle assemblages,...
Extrapolation of near-surface underwater measurements is the most common method to estimate the water-leaving spectral radiance, Lw(λ) (where λ is the light wavelength in vacuum), and remote-sensing reflectance, Rrs(λ), for ocean color algorithm development, and for validation and vicarious calibration of satellite sensors [1-3]. The underwater rad...
Spectrophotometric measurement of particulate matter retained on filters is the most common and practical method for routine determination of the spectral light absorption coefficient of aquatic particles, ap(λ), at high spectral resolution over a broad spectral range. The use of differing geometrical measurement configurations and large variations...
We present a model, referred to as Generalized Stacked Constraints Model (G-SCM), for partitioning the total light absorption coefficient of water (with pure-water contribution subtracted), anw(λ), into phytoplankton, aph(λ), non-algal particulate, ad(λ), and CDOM, ag(λ), components. The formulation of the model is based on the so-called stacked-co...
Two single-waveband low-light radiometers were developed to characterize properties of the underwater light field relevant to biological camouflage at mesopelagic ocean depths. Phenomena of interest were vertical changes in downward irradiance of ambient light at wavelengths near 470 nm and 560 nm, and flashes from bioluminescent organisms. Depth p...
We evaluated the performance of the Quasi-Analytical Algorithm (QAA, v5 with modifications) for deriving the spectral total absorption, a(λ), and backscattering, bb(λ), coefficients of seawater and partitioning of a(λ) into phytoplankton and non-phytoplankton components from input spectrum of remote-sensing reflectance, Rrs(λ), with field data coll...
Many pelagic species, particularly teleost fish, have silvered lateral surfaces that are thought to primarily serve as a form of camouflage. The underlying argument is that the underwater light field is cylindrically symmetrical around the vertical axis; thus a vertical mirror reflects a region of the water column that matches the region directly b...
Variability in the inherent optical properties (IOPs) of seawater and characteristics of the particle assemblage were examined along a transect in the Chukchi Sea during July 2011. This transect encompassed samples from open waters of the marginal ice zone exhibiting low concentrations of chlorophyll-alpha (Chl alpha < 1 mg m(-3)), as well as an ex...
AquaTree is a unique mobile, submersible, spectroradiometer designed for measurement of near-surface light fields in aquatic environments Unlike profiling instruments, the design of AquaTree allows simultaneous up/downwelling radiance and irradiance measurements at multiple depths, enabling integration and averaging of data over multiple time sca...
The solar light field within the ocean from the sea surface to the bottom of the mesopelagic zone was simulated with a radiative transfer model that accounts for the presence of inelastic radiative processes associated with Raman scattering by water molecules and fluorescence of colored dissolved organic matter (CDOM) and chlorophyll-a contained in...
We examined the within-day variability in seawater optical properties and biogeochemical constituents for a high-latitude location in the Ross Sea, Antarctica, during development of the annual spring phytoplankton bloom. Measurements of particulate organic carbon concentration POC, chlorophyll-a concentration Chl, and particle size distribution wer...
André Morel (1933-2012) was a prominent pioneer of modern optical oceanography, enabling significant advances in this field. Through his forward thinking and research over more than 40 years, he made key contributions that this field needed to grow and to reach its current status. This article first summarizes his career and then successively cover...
[1] We developed a model for partitioning the spectral absorption coefficient of suspended marine particles, ap(λ), into phytoplankton, aph(λ), and nonalgal, ad(λ), components based on the stacked-constraints approach. The key aspect of our model is the use of a set of inequality constraints that account for large variability in the aph(λ) and ad(λ...
Partitioning of the total non-water absorption coefficient of seawater,
anw(λ) (i.e., the light absorption coefficient after
subtraction of pure water contribution), into phytoplankton,
aph(λ), and non-phytoplankton,
adg(λ), components is important in the areas of ocean
optics, biology, and biogeochemistry. We propose a partitioning model
based on...
Cephalopods (squids and octopuses) ubiquitously possess reflective
structures in their skin composed of ``reflectin'' proteins. Although a
few simple laminar, Bragg-stack type optical structures have been known
in a handful of common squid species for some time, our extensive survey
of optically active tissues of exotic deep-sea species has reveale...
1] Intense phytoplankton blooms were observed along the Patagonian shelf-break with satellite ocean color data, but few in situ optical observations were made in that region. We examine the variability of phytoplankton absorption and particulate scattering coefficients during such blooms on the basis of field data. The chlorophyll-a concentration,...
A radiative transfer model was applied to examine the effects of vertically stratified inherent optical properties of the water column associated with near-surface plumes of suspended particulate matter on spectral remote-sensing reflectance, R<sub>rs</sub>(λ), of coastal marine environments. The simulations for nonuniform ocean consisting of two l...
For the Japan (East) Sea DRI, our objectives are to coordinate research between US scientists at Scripps Institution of Oceanography, and scientists in Japan and Korea to characterize the detailed optical properties of different water masses in the JES, and to specify the variability in the properties and their potential use as water mass tracers u...
We describe a methodology for determining the volume scattering function β(ψ) of aqueous particle suspensions from measurements with a laboratory multi-angle light scattering instrument called DAWN (Wyatt Technology Corporation). In addition to absolute and angular calibration, the key component of the method is the algorithm correcting for reflect...
An approach that combines a recently developed procedure for improved estimation of surface chlorophyll a concentration (Chl(surf)) from ocean color and a phytoplankton class-specific bio-optical model was used to examine primary production in the Mediterranean Sea. Specifically, this approach was applied to the 10 year time series of satellite Chl...
Under clear skies the underwater light field within the near-surface
ocean shows large fluctuations caused by focusing of sunlight by surface
waves. The downwelling light at near-surface depths can fluctuate
greatly on times scales as short as milliseconds and distances less than
1 cm. Specially designed radiometers and measurement strategies are
r...
Optical measurements including remote sensing provide a potential tool for the identification of dominant phytoplankton groups and for monitoring spatial and temporal changes in biodiversity in the upper ocean. We examine the application of an unsupervised hierarchical cluster analysis to phytoplankton pigment data and spectra of the absorption coe...
LONG-TERM GOALS Our overall goal is to understand the perceptual and mechanistic principles that underlay camouflage framed in the context of the animals' environment. In particular, we plan to characterize and understand the perceptual abilities of several species of benthic and pelagic cephalopods (which are unrivaled masters of dynamic camouflag...
Time series measurements of fluctuations in underwater downward irradiance, Ed, within the green spectral band (532 nm) show that the probability distribution of instantaneous irradiance varies greatly as a function of depth within the near-surface ocean under sunny conditions. Because of intense light flashes caused by surface wave focusing, the n...
1] We have examined empirical algorithms for estimating surface concentration of particulate organic carbon (POC) from remotely sensed ocean color in the Southern Ocean using field data of POC, spectral remote‐sensing reflectance, R rs (l), and the inherent optical properties (IOPs) of seawater collected during a number of cruises. Several algorith...
We apply an innovative approach to time series data of surface chlorophyll from satellite observations with SeaWiFS (Sea-viewing Wide Field-of-view Sensor) to estimate the primary production associated with three major phytoplankton classes (micro-, nano-, and picophytoplankton) within the world's oceans. Statistical relationships, determined from...
