Susanne Craig

• PhD Physics
• Senior Researcher at National Aeronautics and Space Administration

This article proposes a simple and intuitive classification system by which to define full spectral remote sensing reflectance (Rrs(λ)) data with a quantitative output that enables a more manageable handling of spectral information for aquatic science applications. The weighted harmonic mean of the Rrs(λ) wavelengths outputs an Apparent Visible Wav...

Cell abundances of Prochlorococcus, Synechococcus, and autotrophic picoeukaryotes were estimated in surface waters using principal component analysis (PCA) of hyperspectral and multispectral remote-sensing reflectance data. This involved the development of models that employed multilinear correlations between cell abundances across the Atlantic Oce...

NASA's Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission, scheduled for launch in the time frame of late 2022 to early 2023, will carry the Ocean Color Instrument (OCI), a hyperspectral scanning radiometer, and two multiangle polarimeters (MAPs), the UMBC Hyper-Angular Rainbow Polarimeter 2 (HARP2) and the SRON Spectro-Polarimeter for Planet...

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...

Abstract. NASA’s Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission, scheduled for launch in the timeframe of late 2022 to early 2023, will carry the Ocean Color Instrument (OCI), a hyperspectral scanning radiometer, and two multi-angle polarimeters (MAP), the UMBC Hyper-Angular Rainbow Polarimeter (HARP2) and the SRON Spectro-Polarimeter for...

In this study, we present Bayesian machine learning approaches to predict the spectral phytoplankton absorption coefficient - a proxy of phytoplankton biomass - from top of atmosphere measurements of ocean color. This presents a significant advance in ocean color research as it permits the bypassing of conventional atmospheric correction, which is...

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...

This report describes the scientific priorities set by the Canadian Network on Coastal, Oceans and Lake Optics Remote Sensing (NetCOLOR) that aquatic visible remote sensing can address.

The Plankton, Aerosol, Cloud, ocean Ecosystem (PACE; https://pace.gsfc.nasa.gov) mission represents NASA’s next great investment in satellite ocean color and the combined study of Earth’s oceanatmosphere system.

The understanding of the seasonal variability of carbon cycling on the Scotian Shelf in the NW Atlantic Ocean has improved in recent years; however, very little information is available regarding its short-term variability. In order to shed light on this aspect of carbon cycling on the Scotian Shelf we investigate the effects of Hurricane Arthur, w...

Empirical methods based on band ratios to infer chlorophyll-a concentration by satellite do not perform well over the optically complex waters of the St. Lawrence Estuary and Gulf. Using a dataset of 93 match-ups, we explore an alternative method relying on empirical orthogonal functions (EOF) to develop an algorithm that relates the satellite-deri...

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...

The understanding of seasonal variability of carbon cycling on the Scotian Shelf, NW Atlantic Ocean, has improved in recent years, however, very little information is available regarding its short-term variability. In order to shed light on this aspect of carbon cycling on the Scotian Shelf we investigate the effects of Hurricane Arthur, which pass...

Understanding how phytoplankton respond to their physical environment is key to predicting how bloom dynamics might change under future climate change scenarios. Phytoplankton are at the base of most marine food webs and play an important role in drawing CO2 out of the atmosphere. Using nearly 5 years of simultaneous CTD, irradiance, chlorophyll a...

Understanding how phytoplankton respond to their physical environment is key to predicting how bloom dynamics might change under future climate change scenarios. Phytoplankton are at the base of most marine food webs and play an important role in drawing CO 2 out of the atmosphere. Using nearly 5 years of simultaneous CTD, irradiance, chlorophyll a...

Eutrophication is an increasing problem in coastal waters of the Baltic Sea. Moreover, algal blooms, which occur every summer in the Gulf of Gdansk can deleteriously impact human health, the aquatic environment, and economically important fisheries, tourism, and recreation industries. Traditional laboratory-based techniques for water monitoring are...

Laser-based spectroscopic techniques, such as cavity ring-down spectroscopy (CRDS), provide a new, cost effective and more widely available approach to measure the oxygen isotope ratio in water molecules, 18O/ 16O (δ18O), and are used increasingly to measure δ18O in the world's oceans. Here, we present results from an interlaboratory comparison des...

This poster presents a quantitative comparison of the four most commonly used receptor models, namely Absolute Principal Component Scores (APCS), Pragmatic Mass Closure (PMC), Chemical Mass Balance (CMB), and Positive Matrix Factorization (PMF) used to predict the contributions of a wide variety of sources to PM2.5 mass in Halifax, Nova Scotia duri...

An equation for the rate of photosynthesis as a function of irradiance introduced by T. T. Bannister included an empirical parameter b to account for observed variations in curvature between the initial slope and the maximum rate of photosynthesis. Yet researchers have generally favored equations with fixed curvature, possibly because b was viewed...

In this study, we used comparative metaproteomics to investigate the metabolic activity of microbial plankton inhabiting a seasonally hypoxic basin in the Northwest Atlantic Ocean (Bedford Basin). From winter to spring, we observed a seasonal increase in high-affinity membrane transport proteins involved in scavenging of organic substrates; Rhodoba...

Phytoplankton plays a critical role in the uptake of atmospheric carbon dioxide by the ocean, and is comprised of a spectrum of cell sizes that are strongly associated with different oceanographic conditions. Studies suggest that the ocean will become increasingly stratified in response to a warming climate, limiting nutrient exchange to the upper...

Little information exists concerning (i) source contributions to airborne particulate pollution in Qatar, (ii) the potential impact that deteriorating air quality may have on the respiratory health of residents, and (iii) how climate change may affect respiratory health through its impact on air quality. Air quality in Qatar may be negatively affec...

Much of the variability in the surface ocean's carbon cycle can be attributed to the availability of sunlight, through processes such as surface heat flux and photosynthesis, which regulate carbon flux over a wide range of time scales. The critical processes occurring on timescales of a day or less, however, have undergone few investigations, and m...

The short, but intense spring bloom, occurring late March to early April on the Scotian Shelf in the northwest Atlantic draws down approximately 50% of the total carbon fixed over the annual cycle in this region. In the spring and summer months following the collapse of the bloom, nutrient and chlorophyll levels plummet suggesting that further draw...

Utilizing global satellite ocean color imagery, a feature characterized by enhanced reflectances has been identified in the Southern Ocean. This feature encircles the globe from ~30°S to ~60°S, and has been consistently observed during austral summers throughout the entire MODIS-Aqua mission (Balch et al. 2011). When these reflectances are input in...

Using large-scale field surveys across 12 estuaries in two provinces in Atlantic Canada, we analyzed changes in phytoplankton and benthic macroalgal communities as well as the canopy structure of eelgrass beds and quantified their carbon and nitrogen storage with increasing eutrophication. As eutrophication increased, phytoplankton biomass increase...

Much of the variability in the surface ocean's car-bon cycle can be attributed to the availability of sunlight, trig-gering surface heat flux and photosynthesis, which in turn regulate the biogeochemical cycling of carbon over a wide range of time scales. The critical processes of this carbon cy-cle regulation, occurring at time scales of a day or...

An approach to develop accurate local models for the estimation of chlorophyll a concentration (Chl a) and spectral phytoplankton absorption (a(ph)(lambda)) from hyperspectral in situ measurements of remote sensing reflectance (R-rs(lambda)) in an optically complex water body is presented. The models are based on empirical orthogonal function (EOF)...

Much of the surface ocean carbon cycle variability can be attributed to the availability of sunlight, through processes such as heat fluxes or photosynthesis, which regulate the ocean carbon cycle over a wide range of time scales. The critical processes occurring on timescales of a day or less, however, have undergone few investigations, and most o...

Much of the variability in the surface ocean's carbon cycle can be attributed to the availability of sunlight, through processes such as heat fluxes and photosynthesis, which regulate over a wide range of time scales. The critical processes occurring on timescales of a day or less, however, have undergone few investigations, and most of these have...

The coastal oceans have relatively large fluxes of CO2, but the temporal variability of these systems is high. Compared to open ocean systems, the variability of the CO2 system in coastal regions remains poorly understood. The Scotian Shelf is a highly productive area of the Canadian northwestern Atlantic Ocean. The region is host to active fisheri...

We develop an algorithm to compute pCO2 in the Scotian Shelf region (NW Atlantic) from satellite-based estimates of chlorophyll-a concentration, sea-surface temperature, and observed wind speed. This algorithm is based on a high-resolution time-series of pCO2 observations from an autonomous mooring. At the mooring location (44.3° N and 63.3° W), th...

We develop an algorithm to compute p CO₂ in the Scotian Shelf region (NW Atlantic) from satellite-based estimates of chlorophyll- a concentration, sea-surface temperature, and observed wind speed. This algorithm is based on a high-resolution time-series of p CO₂ observations from an autonomous mooring. At the mooring location...

The rise in atmospheric CO2, due to anthropogenic emissions, is partially offset by the ocean's CO2 uptake. Direct measurements of surface-ocean CO2 partial pressure (pCO2) are required to accurately assess the seasonal and interannual variability of air-sea CO2 fluxes. The coastal oceans have relatively large fluxes of CO2, but the temporal variab...

We develop an algorithm to compute pCO2 in the Scotian Shelf region (NW Atlantic) from satellite-based estimates of chlorophyll-a concentration, sea-surface temperature, and observed wind speed. This algorithm is based on a high-resolution time-series of pCO2 observations from an autonomous mooring. At the mooring location (44.3° N and 63.3° W), th...

Concurrent 24-hr samples of particulate matter of median aerodynamic diameter less than 10 microm (PM10) were collected over a 10-day period in August 2000 at four sites along a transect in west-central Scotland, UK (passing from the coast through the city of Glasgow) in line with the prevailing southwesterly wind. Each sample was analyzed for chlo...

We applied two numerical methods to in situ hyperspectral measurements of remote sensing reflectance R rs to assess the feasibility of remote detection and monitoring of the toxic dinoflagellate, Karenia brevis, which has been shown to exhibit unique absorption properties. First, an existing quasi-analytical algorithm was used to invert remote sens...

The relationship between inherent optical properties (IOPs), phytoplankton community structure and the abundance of suspended particles in the size range 3–500 μm was studied near the Isles of Scilly (UK) in May 2000. Autosub, an autonomous submersible vehicle specifically designed for science missions, was used as an instrument-positioning platfor...

Values for the coefficients of absorption (a) and attenuation (c) obtained from AC-9 measurements in coccolithophore blooms do not provide satisfactory inputs for radiance transfer models. We have therefore modified the standard AC-9 scattering correction algorithm by including an extra term, F(λ, λ r ), which allows for possible wavelength depende...

A model that relates the coefficients of absorption (a) and backscattering (b b ) to diffuse attenuation (K d ), radiance reflectance (R L ), and the mean cosine for downward irradiance (μ d ) is presented. Radiance transfer simulations are used to verify the physical validity of the model for a wide range of water column conditions. Analysis of th...

Thesis (Ph. D.)--University of Strathclyde, 2000.