Oceanographer

NASA Goddard Space Flight Center - Greenbelt, MD

June 2002 - Present

Research Oceanographer  in the Ocean Ecology Laboratory is responsible for conducting research related to ocean biogeochemistry, the processing and cycling of dissolved and particulate organic matter,  the global carbon cycle, and applications as related to the utilization of marine resources. Efforts are primarily targeted toward developing capabilities to interpret remotely sensed data from NASA and other satellites and aircraft. This requires a general appreciation of a wide variety of chemical, physical, and biological problems, such as biogeochemical analyses in the laboratory and in the field, and the development of new algorithms for numerical models of the bigeochemical system.

Research Chemist/Mendenhall Post-Doctoral Fellow

USGS - Reston, VA

January 2001 - June 2002

Conduct investigations on the impacts of climate variability and anthropogenic perturbations on source contributions of organic matter to estuarine sediments using lipid biomarkers and stable isotope analyses.

Assistant Research Scientist

Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science - Solomons, MD

March 2000 - January 2001

Post-doctoral position investigation the chemical composition, sources and cycling of organic matter in coastal marine ecosystems.

Graduate Research Assistant

Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science - Solomons, MD

September 1994 - March 2000

Graduate research investigating the chemical composition, sources and reactivity of coastal organic matter

Graduate Research Assistant

University of Texast at Austin Marine Science Institute - Marine Science Institute Port Aransas, TX

May 1993 - August 1994

Graduate research studying how environmental and ecological factors influence the spatial distribution of macrobenthos community structure.

Teaching Assistant

University of Texas at Austin - Austin, TX

September 1992 - May 1993

Teaching assistant for introductory course on oceanography.  Duties involved leading two weekly discussion sessions that included lectures, discussions, and homework assignments.

Impacts of estuarine processes on delivery of Arctic riverine materials to the near coastal environment: Implications for water quality and biogeochemical cycling in preparation for Arctic-COLORS

Carbon Cycle

The research objectives focusing on the lower Yukon River, delta, and adjacent Norton Sound and coastal sites in the Beaufort Sea include :

1. Characterize and quantify changes in concentrations and composition of organic and inorganic materials from the watershed-aquatic interface and the head of tides through low salinity riverine gradients.
2. Capture baseline conditions in riverine/estuarine chemical compositions and fluxes to the nearshore environment in support of future Arctic-COLORS research efforts.
3. Examine changes in Arctic coastal conditions over past two decades by applying prior ocean color satellite observations along with data synthesis of past studies.
 

Program Support Office for Calibration and Validation of Ocean Color Satellite Missions

Remote Sensing

The overall goal of the NASA Ocean Ecology Laboratory (OEL) Field Support Group (FSG) at Goddard Space Flight Center (GSFC) is to provide basic field observation and data analysis capabilities in support of the NASA Ocean Biology and Biogeochemistry Program (OBB) and related missions. This is to be accomplished by participating in field experiments and cruises, workshops, and professional meetings in collaboration with the research community, instrument vendors, and other agencies. This project provides NASA two core elements to support its existing ocean color satellite data processing element at Goddard (Ocean Biology Processing Group): (1) a cooperative field program that advances the state-of-the-art of in- and above-water optical and biogeochemical measurements, which are critical for calibration and validation of the satellite radiometry and for development and refinement of ocean color algorithms; and, (2) a global network of partnerships, within which to share international expertise and distribute the burden of maintaining a global field program with high temporal and spatial resolution. Our work encompasses two central themes: (1) the need to quantify and refine the accuracies of field observations, with attention to both data collection and data processing; and, (2) the importance of international partnerships, the need for which gains in prominence as the likelihood of a data gap in the U.S. ocean color time-series steadily increases (both SeaWiFS and MODIS-Aqua have far exceeded their operationally-designated mission lifetimes). With regards to the former, the challenge will be to extend the accomplishments achieved in the open ocean into much shallower and optically complex waters. New mission concepts emphasize coastal research in optically complex waters and, as such, require field observations with high accuracies, sampling resolutions, sensitivities, and dynamic ranges. With regards to the latter theme, the estimation of uncertainty budgets, the refinement of protocols, the execution of interdisciplinary field campaigns and maintenance of vicarious calibration sites, and the submission of in situ data to a centralized archive have all benefitted from participation of the international community, particularly when supported and coordinated by a centralized program support office.

Arctic-COLORS (Arctic-COastal Land Ocean inteRactions) field campaign scoping Study

Carbon Cycle

Arctic-COLORS is a field campaign scoping study funded by NASA's Ocean Biology and Biogeochemistry Program that aims to improve understanding and prediction of land-ocean interactions in a rapidly changing Arctic coastal zone, and assess vulnerability, response, feedbacks and resilience of coastal ecosystems, communities and natural resources to current and future pressures.

Support of NASA Ocean Biology and Biogeochemistry Research with Quality-Assured HPLC Pigment Analysis

Analysis

Important Earth Observation System objectives are to quantify Chlorophyll a (Chla) in marine environments, know the measurement uncertainty and ensure data are valid over the long-term. Chla is one of the standard MODIS products produced by NASA Ocean Biology Processing Group. Most satellite missions require on-orbit accuracy to within 35%. For remote sensing validation of Chla, High Performance Liquid Chromatography (HPLC) is the reference method. Assuming total uncertainty is split evenly between satellite and field components, the HPLC accuracy for Chla must be within 25%, but accuracy within 15% (presumably) offers opportunities to improve remote sensing algorithms. Intercalibrations among laboratories (primarily the SeaHARRE (SeaWiFS HPLC Analysis Round-Robin Experiment) activities) that measure marine pigments have demonstrated that average accuracy for Total Chla to within 6-7% is possible, for laboratories that follow a quality assurance (QA) process. For other pigments, average accuracy to within 25% is possible; in many instances accuracy can be improved to 15% if methods are quality-assured.
An important result of the SeaHARRE HPLC intercomparisons was the identification of performance criteria that allow a determination of whether a method is capable of achieving specific accuracy requirements. The GSFC Field Support Group (FSG) maintains a detailed QA plan to ensure compliance with these performance metrics established during SeaHARRE activities and consistent results in between such activities. A QA plan includes repetitive quality control measurements and routine assessment to ensure these measurements fall within quantified limits, for in the absence of such rigor, it is not possible to know whether the above-described accuracy requirements set for researchers is being achieved.
For this project, GSFC’s FSG is providing quantitative concentration results for up to 3000 samples collected by Ocean Biology and Biogeochemistry (OBB) investigators under certain NASA grants for 12 primary pigments (including their secondary components) and selected tertiary pigments, as defined in SeaHARRE intercalibration activities, plus relevant pigment sums and ratios. Reported results will also include information about the limit of quantitation (LOQ) and measures of analysis precision at the time of data collection. This activity would provide the necessary field measurements of HPLC-derived Chla for NASA PIs to support validation and continued maintenance of the MODIS Chla algorithm.
GSFC FSG chromatographers have consistently produced state-of-the-art pigment results, as evidenced by performance during inter-laboratory comparisons (averaging 5.2% for TChla and 11.7% for other pigments). The FSG maintains strict adherence to a HPLC QA plan, and personnel offer sixteen years of experience providing quantitative pigment analyses to multiple clients, and fourteen years of experience researching method improvements, specifically as they relate to improving accuracy and precision of results.

Impacts of estuarine processes on delivery of Arctic riverine materials to the near coastal environment: Implications for water quality and biogeochemical cycling

The research objectives focusing on the lower Yukon River, delta, and adjacent Norton Sound and coastal sites in the Beaufort Sea include : 

1. Characterize and quantify changes in concentrations and composition of organic and inorganic materials from the watershed-aquatic interface and the head of tides through low salinity riverine gradients.
2. Capture baseline conditions in riverine/estuarine chemical compositions and fluxes to the nearshore environment in support of future Arctic-COLORS research efforts.
3. Examine changes in Arctic coastal conditions over past two decades by applying prior ocean color satellite observations along with data synthesis of past studies.
 

Develop and validate bio-optical algorithms to expand the breadth of biogeochemical and biological products derived from the PACE mission

Ocean color satellite algorithm development and validation of data products for colored dissolved organic matter absorption (CDOM), dissolved (DOC) and particulate organic carbon (POC), phytoplankton pigments and taxonomy using PACE's hyperspectral UV-Vis-NIR and high spectral resolution capabilities.

Production and Application of Hourly Observations from the Korean Geostationary Ocean Color Imager (GOCI)

As the first and only geostationary ocean color sensor, the Korean Geostationary Ocean Color Imager (GOCI) will revolutionize satellite remote sensing of ocean biology and biogeochemistry.  The goal of the work is to accelerate the development, production and distribution of validated GOCI data products to U.S. and non-U.S. scientific communities through a strong collaboration between the Korea Ocean Satellite Center (the Korean GOCI data processing, distribution, and analysis team) at the Korea Institute of Ocean Science and Technology (KIOST) and Goddard Space Flight Center’s Ocean Ecology Lab (OEL), which includes the Ocean Biology Processing Group (OBPG). OEL works with KOSC to accomplish the following objectives: (1) establish a mirror site to distribute GOCI L1B data to U.S. and non-U.S. scientific communities, (2) implement GOCI data processing and algorithms into NASA’s common data processing software (SeaDAS), (3) generate, validate and distribute NASA OBPG standard ocean color products for the duration of the GOCI mission, and (5) apply field measurements to develop, validate and analyze new regional GOCI products of dissolved and particulate absorption and organic carbon.  From the vantage point of geostationary orbit, GOCI images the 2500 x 2500 km region surrounding the Korean peninsula eight times per day. Such high frequency observations will advance our knowledge of the rates of several biological and biogeochemical processes including primary productivity, net community production and photooxidation of dissolved organic matter as well as the impacts of physical processes such as tides, eddies, surface currents, and river discharge on the distribution and fluxes of ocean constituents. Furthermore, this research will enhance our understanding of how geostationary ocean color data can be applied to study ocean ecosystems in preparation for future NASA geostationary ocean color missions. The principal achievement of this effort is to promote broad utilization of GOCI data by the U.S. and international scientific community.

Arctic-COLORS: Coastal Land Ocean Interactions

Arctic-COLORS is a NASA Ocean Biology and Biogeochemistry Program field campaign scoping study that aims to quantify the coupled biogeochemical/ecological response of the Arctic nearshore system to rapidly changing terrestrial fluxes and ice conditions, in the context of environmental and climate change.
 

Climate variability impacts on U.S. East Coast (CliVEC)

Examination of the impact of climate variability on primary productivity and organic carbon distributions along the northeastern U.S. continental margin.

Application of ocean color satellite observations to study the carbon cycle and ecology of marine ecosystems.

Application of SeaWiFS, MODIS and MERIS satellite data products to quantify the inventories and fluxes of colored dissolved organic matter absorption (CDOM), dissolved (DOC) and particulate organic carbon (POC), phytoplankton pigments and taxonomy to quantify seasonal and interannual variability in the inventories and fluxes of DOC, POC and CDOM, net ecosystem production of DOC, and phytoplankton community composition.

Coastal biogeochemical model development and evaluation

Contribute to the development and evaluation of the biogeochemical model developed by the NASA USECoS team (U.S. Continental Shelf). The team applies the NENA (Northeastern North America; 3D coupled biogeochemical-physical) coastal ocean model and linked terrestrial model (DLEM) to study carbon and nitrogen cycling and ecosystem dynamics along the U.S. east coast watersheds and continental margin.

American Geophysical Union

2002 - Present