Research

Transit to Antarctica in Drake Passage, Southern Ocean 

Research Interest: satellite remote sensing, data science, machine learning, ocean optics, bio-optics, polar oceanography, coastal oceanography, phytoplankton ecology, biological oceanography. 

Advancing the state-of-the-art in marine technology to facilitate the big-data paradigm shift in the ocean industry.

(also marine biogeochemistry, primary productivity, carbon export and sequestration, nutrient cycles of macro- & trace elements and ocean iron fertilization).

Methodology Interest: a multidisciplinary method combining field work, remote sensing, numerical models, data science and machine learning. 

Geographic Interest: the polar regions / high-latitude environments, ice-ocean boundary, High-Nutrient-Low-Chlorophyll (HNLC) regions, particularly the Southern Ocean. 

Research Gate

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Sea surface glacial meltwater fraction (SSGM) as a percentage of total seawater, 2010--2020 climatology of the Austral summer months over the Antarctic Peninsula

Remote Sensing of Sea Surface Glacial Meltwater on the Antarctic Peninsula Shelf

Abstract: Glacial meltwater is an important environmental variable for ecosystem dynamics along the biologically productive Western Antarctic Peninsula (WAP) shelf. This region is experiencing rapid change, including increasing glacial meltwater discharge associated with the melting of land ice. To better understand the WAP environment and aid ecosystem forecasting, additional methods are needed for monitoring and quantifying glacial meltwater for this remote, sparsely sampled location. Prior studies showed that sea surface glacial meltwater (SSGM) has unique optical characteristics which may allow remote sensing detection via ocean color data. In this study, we develop a first-generation model for quantifying SSGM that can be applied to both spaceborne (MODIS-Aqua) and airborne (PRISM) ocean color platforms. In addition, the model was prepared and verified with one of the more comprehensive in-situ stable oxygen isotope datasets compiled for the WAP region. The SSGM model appears robust and provides accurate predictions of the fractional contribution of glacial meltwater to seawater when compared with in-situ data (r = 0.82, median absolute percent difference = 6.38%, median bias = −0.04), thus offering an additional novel method for quantifying and studying glacial meltwater in the WAP region.



PRISM airborne data of  (left) enhanced RGB image depicting icebergs and a trail of bergy bits, and (right) sea surface glacial meltwater fraction. 

Commentary: The polar ecosystem in Antarctica hosts important toothfish and krill fisheries that have significant economic value. This highly productive ecosystem also offers an abundant amount of majestic megafauna (e.g., seals, whales, and penguins) which attract tens of thousands of tourists each year. Therefore, it is important to study this ecosystem and understand the ecological impact of environmental change. At the base of this vibrant ecosystem is marine phytoplankton; their abundance and community composition are directly influenced by the ambient environment. In recent years, multiple studies have found a positive correlation between glacial meltwater and phytoplankton biomass. These studies have found that glacial meltwater is likely a source of nutrients, particularly dissolved iron, as well as being a proxy for meltwater-buoyancy-driven upwelling and wind-driven upwelling of deep nitrate and dissolved iron along the ice-ocean interface. In addition, meltwater is found to enable surface layer stabilization and reduce the depth of mixing, thus leading to higher light availability for phytoplankton. 

The Western Antarctic Peninsula (WAP) is one of the most productive regions on Earth, and it offers an natural observatory to study polar ecosystems. In the WAP, prior studies have found a profound impact of glacial meltwater on phytoplankton community, which is beyond changes in mere salinity. In WAP fjords, glacial meltwater is a pathway for delivering macro- and micro-nutrients to the surface. Sporadic but prolonged katabatic wind events bring up deep nitrate-rich water which is propagated along the surface with glacial meltwater from the ice-ocean interface. Dissolved iron is supplied to the surface via a similar mechanism, but it can also directly enter the ambient water column via sub-glacial and sub-marine melting of glaciers. These results indicate that glacial meltwater plays an important role near the ice-ocean boundary, and glacial meltwater export from fjords likely serves as an important nutrient source for the broader ecosystem in the WAP. 

Landsat 8 (LC08_L2SR_218109_20230226_20230301_02_T2_SR_RGB) depicting southern Marguerite Bay and glacial outlet situated north of Alexander Island. 

Satellite imagery retrieved from NASA/USGS Landsat 8 Scene ID LC82191052016109LGN00 illustrating one of the primary study sites in the Western Antarctic Peninsula

Doctorate Dissertation: The Impact of Seasonal Environmental Variables on Phytoplankton Ecology at the Antarctic Ice-Ocean Boundary: Studies through field work, numerical models, data science, and machine learning. Scripps Institution of Oceanography, University of California San Diego 

Dissertation Abstract: The Western Antarctic Peninsula (WAP) is rapidly changing due to climate forcing in recent decades. These changes manifest as an overall increase in ocean and air temperatures (with some regional cooling), retreating glaciers, and increases in precipitation associated with shifts in atmospheric circulation. As these changes continue and intensify, meteoric water input to the coastal ocean is expected to increase. Continued monitoring of these changes can help us better understand their impacts. The physical effects of glacial melting on sea level has been extensively studied in the past. However, the impact of glacial meltwater on phytoplankton community composition remains largely elusive. Due to the critical role of primary producers in the Antarctic food web and their significance to local biogeochemical cycle and ecosystem dynamics, the immediate ramification of meltwater input on these communities need to be better understood.

This dissertation contains three main chapters. In Chapter 2, I aim to understand the spatial and temporal distribution of glacial meltwater in Andvord Bay and characterize their optical features in order to develop a method for quantifying meltwater fraction based on water column optics. The fjord severs as an end-member and thus an extreme in various environmental and biological gradients. Hence, the ecological connectivity between the fjord and the shelf has significant implications to the entire Antarctic ecosystem. In Chapter 3, I investigate the phytoplankton community composition within Andvord Bay and understand how environmental conditions, particularly meltwater, impact this community. Data from this chapter are utilized to train a machine learning model to predict phytoplankton abundance and community composition. The techniques developed in this chapter is applied to the broader ecosystem over the WAP continental shelf in Chapter 4. I hope this dissertation can improve our understanding of how environmental variables influence phytoplankton community in the WAP, as well as contextualize the physical impacts of climate forcing in the perspective of Antarctic ecosystems.



Iceberg A-57A originated from the Larsen Area, April 2018

KOPRI's Icebreaking Research Vessel ARAON sampling sea ice in the Weddell Sea, April 2018

Sea ice diatom microscopy in the Weddell Sea, April 2018

Marine Ecosystem Response to the Larsen C Ice−Shelf Breakout: “Time Zero” (NSF Larsen C Field Campaign)

Project Summary: The project seeks to evaluate pelagic-benthic communities in the area of the recently retreated Larsen C ice shelf in order to characterize the initial conditions of the coastal ecosystem exposed after millennia of being covered by ice. The team worked with the Korean Polar Research Institute, KOPRI, scientists in an international effort to sample in the lead developed between the Larsen C ice shelf and the A-68 iceberg to characterize water column, benthic and surface sediments of an under-ice ecosystem, and will sample seaward of the iceberg, to provide open-ocean ecosystem comparisons. 

The cruise did not reach Larsen C due to very unfavorable ice conditions. However, we took the opportunity and utilized our remaining ship time to study another massive iceberg (A-57 A) which also originated from the Larsen area.  Currently, the long-term impact of accelerated warming on sea level rise has been extensively studied, however the more immediate influence of glacial input on phytoplantkon ecology and food web is still not well understood. By studying these icebergs in the aftermath of ice shelf collapse, we can achieve a better understanding of the direct impact of climate change on polar ecosystems and biogeochemistry. 


More photography from this expedition: 

Open Sea, Antarctica, Science, Plankton Microscopy

Jack deploying HS-6 instrument to measure light backscattering in Andvord Bay, Western Antarctic Peninsula on board of Research Vessel Icebreaker Nathaniel B. Palmer


Landing at Neko Harbor to set up weather station and collect benthic algal mats


Gentoo penguins in Neko Harbor


Deploying HS-6 on board of Research Vessel Laurence M. Gould in Andvord Bay


Fjord Ecosystem Structure and Function on the West Antarctic Peninsula – Hotspots of Productivity and Biodiversity (NSF FjordEco Field Campaign)

Project Summary: Marine communities along the Western Antarctic Peninsula (WAP) are highly productive ecosystems which support a diverse assemblage of charismatic animals such as penguins, seals, and whales as well as commercial fisheries including for Antarctic krill. The WAP also contains many fjords (deep estuaries carved by glacial ice) with active glaciers entering the ocean; these fjords appear to be intense, potentially climate sensitive, hotspots of biological production and biodiversity. Because of intense biological activity and abundant charismatic fauna, these fjords are also major destinations for a large Antarctic tourism industry. Nonetheless, the structure and dynamics of these fjord ecosystems are very poorly understood.

The FjordEco project is an integrated field and modeling program designed to evaluate physical oceanographic processes, glacial inputs, water column community dynamics, and seafloor bottom community structure and function in these important yet little understood fjord systems. These Antarctic fjords have characteristics that are substantially different from well-studied Arctic fjords, likely yielding much different responses to environmental change. FjordEco is designed to provide major new insights into the dynamics and climate sensitivity of Antarctic fjord ecosystems, highlighting contrasts with Arctic sub-polar fjords, and potentially transforming our understanding of the ecological role of fjords in the rapidly warming west Antarctic coastal marine landscape. Our project will also further the NSF goal of training new generations of scientists, providing scientific training for undergraduate, graduate and postdoctoral students. This includes the unique educational opportunity for undergraduates to participate in research cruises in Antarctica and the development of a novel summer graduate course on fjord ecosystems. Internet-based outreach activities will be enhanced and extended by the participation of a professional photographer who will produce magazine articles, websites, radio broadcasts, and other forms of public outreach on the fascinating Antarctic ecosystem.

FjordEco involves a 15-month field program to test mechanistic hypotheses concerning oceanographic and glaciological forcing, and phytoplankton and benthic community response in the Antarctic fjords. Those efforts will be followed by a coupled physical/biological modeling effort study to evaluate the drivers of biogeochemical cycles in the fjords and to explore their potential sensitivity to enhanced meltwater and sediment inputs. Fieldwork over two oceanographic cruises aboard the NSF ships the Laurence M. Gould and the Nathaniel B. Palmer in late 2015 and the spring of 2016 will utilize moorings, weather stations, and glacial, sea-ice and seafloor time-lapse cameras to obtain an integrated view of fjord ecosystem processes. The field team will also make multiple shipboard measurements and will use towed and autonomous underwater vehicles to intensively evaluate fjord ecosystem structure and function during spring/summer and autumn seasons. These integrated field and modeling studies are expected to elucidate fundamental properties of water column and sea bottom ecosystem structure and function in the fjords, and to identify key physical-chemical-glaciological forcing in these rapidly changing ecosystems. 




Kerguelen Plateau, MODIS true color, data retrived from NASA Goddard Space Flight Center (GSFC)


Post-processed MODIS-Aqua global chlorophyll concentration; ocean color data retrieved from NASA GSFC.


Phytoplankton bloom in the Barents Sea, Data captured on August 14th, 2011. MODIS-Aqua "near-true-color" data, retrieved from NASA.

Analysis of the Variations in Phytoplankton Blooms in the Vicinity of Kerguelen Plateau

by B. Jack Pan, J. Keith Moore

Abstract: Ocean color data reveals the seasonal/interannual variations in phytoplankton bloom distributions in the vicinity of Kerguelen Plateau. These variations in chlorophyll concentration are related to seasonal light conditions, iron cycling, and sea floor depth. In Austral Spring/Summer between 2002 and 2013, we observed the highest chlorophyll concentrations in the shallower plateau area, with elevated chlorophyll concentrations also seen downstream of the plateau.  Upstream areas had consistently low chlorophyll concentrations. Seasonally, chlorophyll concentration peaks during December in all three regions. These results demonstrate that the sedimentary iron input from the shallow sea floor over the Kerguelen Plateau induced significant blooms; the mode and timing of iron addition to the Southern Ocean can affect the bloom size and potentially influence carbon sequestration efficiency. This study allows an improved understanding on how chlorophyll concentration responds to natural sedimentary inputs, but the inclusion of recent data also reveals how chlorophyll responds to climate forcings.  We compare satellite chlorophyll imagery with output from the Community Earth System Model (CESM) in this region to evaluate the model and help with interpretation of the satellite data.  Natural Fe-induced blooms are useful for studying the role of Fe in marine biogeochemistry, and it can also help us to achieve a better understanding of ocean Fe fertilization as a potential climate change intervention strategy.

Thoughts on ocean geoengineering (an introduction from 2010): 
I have a strong interest in earth observation through remote sensing techniques. In particular studying phytoplankton and marine nutrient biogeochemical cycles with a focus on iron fertilization. Anthropogenic carbon concentration has increased significantly since the industrial revolution. This excess of atmospheric carbon led to the accelerating trend of warming observed in climate records. The effects of warming include changes in Earth’s climate and reduction in human wellbeing. The current rates of regulatory reform and cutting emission are clearly not fast and effective enough to mitigate the cost of climate change; furthermore, the long residence time of CO2 will ensure the continuation of warming even if all forms of carbon emission is eliminated effectively and immediately. Though cutting emission and raising awareness should always be our top priorities in dealing with climate change, more time is needed for these strategies to become effective. Geoengineering (especially carbon sequestration) offers such opportunity to aid these conventional strategies and it is also capable of actively and directly tackle a source of climate change.
~20% of world's ocean is HNLC and lacking phytoplankton growth due to the absence of a limiting trace nutrient, iron. By artificially adding iron to these parts of the ocean through correct mode and timing, we can induce blooms and potentially reduce atmospheric CO2 concentration significantly. I believe it is very important to assess both the short and long-term impacts of iron fertilization, and natural mechanisms that can allow a greater carbon export from iron-induced blooms. Remote sensing and model studies coupled with field data may one day allow us to develop a feasible plan to effectively export excess CO2 to the deep ocean for a long period of time, and thus end climate change. Furthermore, I am interested in the method of investigation as much as the science; advancements in satellite sensors and remote sensing techniques can make that plan a reality in the near future. It is indeed a pressing but very exciting time to be working in this field.

NASA Earth Science Directorate, Applied Sciences, DEVELOP Program

Applied Remote Sensing Oceanography Projects

Team Lead/Consultant, NASA DEVELOP at Jet Propulsion Laboratory (2014)

“Remote Sensing Detection of Wastewater Plumes to Assess Public Water Quality in Los Angeles and Orange Counties”

Abstract: Treated sewage from the City of Los Angeles Hyperion Wastewater Treatment Plant (HWTP) and the Orange County Sanitation District (OCSD) are released through 5-mile long outfall pipes offshore. Normally this treated wastewater remains at depths below the local thermocline and photic zone. The two plants on occasion conduct repair and maintenance services on the main outfall pipes; during these service periods, treated sewage is temporally diverted to a shorter pipe that only extend into shallow coastal zones, where the buoyant, freshwater plumes containing nutrients may disperse into the surface waters and photic zone. Two such events have taken place: one at the Hyperion Plant in November 2006; and the other in fall 2012 at OCSD. In both cases, the treated wastewater was diverted from the main 5-mile (8.05 km) long pipes terminating at approximately 60 m depth, to shorter 1-mile (1.61 km) pipes that end at about 20 m depths. These diversion events can potentially impact coastal ecosystems and public health. This study focuses on the analysis of remote sensing data from multiple satellite sensors for these two cases to produce an assessment on the plumes’ thermal signature, impact on coastal biogeochemistry, and surface movement. The results are compared with in situ data for validation. These results not only allow a better understanding of the diverted outfall plume, but they also assist the development of a strategy for improved satellite detection during future diversion events.

Project Partners/Collaborators 

·  City of Los Angeles Hyperion Treatment Plant (HWTP)

·  Orange County Sanitation District (OCSD)

·  Southern California Coastal Water Research Project (SCCWR)

Benefits to End-User

· Improved satellite detection methods of future diversions. 

· Improved understanding of plume dynamics in Southern California Bight.

Publication

Gierach, M.M., Holt, B., Trinh, R., Pan, B.J. and Rains, C. (2016). Satellite detection of wastewater diversion plumes in Southern California. Estuarine, Coastal and Shelf Science.

http://www.sciencedirect.com/science/article/pii/S0272771416304449

Earthzine Virtual Poster Session -- A project overview through a children's documentary "Don't Wastewater": http://www.earthzine.org/2014/08/03/dont-wastewater-tracking-wastewater-plumes-along-southern-california-beaches/

NASA Earth Science Directorate, Applied Sciences, DEVELOP Program

Applied Remote Sensing Oceanography Projects

Consultant, NASA DEVELOP at Jet Propulsion Laboratory (2013)

“Synthetic Aperture Radar Data Decision Support for Atlantic Bluefin Tuna Population Assessment and Management in the Gulf of Mexico” 

Abstract: The Atlantic Bluefin Tuna (Thunnus thynnus Thunnus) is one of the largest marine vertebrates. The species is in high demand at sushi markets and it’s also a highly political species managed internationally by the International Commission for the Conservation of Atlantic Tuna (ICCAT). The Gulf of Mexico is one of only two spawning sites in the world for this particular species; however there is a large variance in estimates of adult Blue-fin Tuna spawning. This study focuses on extending Earth science research results to the existing National Oceanic and Atmospheric Administration’s (NOAA) National Marine Fisheries Service (NMFS) decision-making system for population assessment and management of the Bluefin Tuna. The goal is to reduce the variance in the estimates of adult Atlantic Bluefin Tuna spawning stock abundance in the Gulf of Mexico (GOM) through the development of spawning site habitat classification and catchability indices of the larvae. These will be derived from the innovative use of several earth observing satellites with a focus on synthetic aperture radar (SAR) data.  Sargassum is a spawning site for Bluefin Tuna, as well as a habitat for its prey. SAR is capable of detecting Sargassum at the ocean’s surface and so it can effectively indicate the presence of commercial fish species. This study will provide maps of Sargassum distribution as well as an approach to isolate the returns from other ocean features that have similar strong backscatter including natural seeps, oil spills, and biogenic films.

Project Partners/Collaborators 

·  Roffer’s Ocean Fishing Forecasting Service 

·  University of Southern Mississippi 

·  NOAA National Marine Fisheries Service

Benefits to End-User

·  Enhanced detection of Sargassum using ASAR sensor for Roffer’s Forecasting Service and as a decision support tool in surveying and larvae sampling. 

·  Pattern recognition of Sargassum visible in ASAR sensor for NOAA National Marine Fisheries Service as a decision-making tool for population management and assessment of the Blue-fin Tuna. 

·  Enhanced detection of Sargassum using ASAR sensor for University of Mississippi’s impact study of Deepwater Horizon Oilspill on Sargassum and other marine species. 

Plant Guild Composers Project (2012 -- 2013) 

Dept. of Informatics, UC Irvine

Norton, J., S. Nayebaziz, S. Burke, B. Pan, and B. Tomlinson (2014) “Plant Guild Composer: An Interactive Online System to Support Back Yard Food Production.” Demonstration. CHI Conference. Accepted. 

· A design project that attempts to create a functional ecosystem of urban food forest by integrating information technology, remote sensing, and ecology.

· Calibrate programmers’ work on ecological concepts and assisted conceptual artist with UI design concepts.

· Cartographer, created maps of local environmental variables to aid site analysis.

The current database consists of more than 3,000 environmental topics. This figure shows the relationships among them (Credit: Social Code Group, Joel Ross) 

The Causality Project (2011 -- 2012)

Dept. of Informatics, UC Irvine

·         Causality Project aims to provide the users with a participatory environment where they can identify Environmental issues and attach causal links to these issues. 

·         Users can access the Wikipedia information and geo-tagged media associated with these issues and locate geographic instances of these problems on Google Maps.

Greenland coast, MODIS True Color Imager, NASA GSFC

Greenland sea ice conditions by MODIS Imagery

Research Assistant, Rignot’s Group, Dept. of Earth System Science, UC Irvine (2013)

· Compiled and analyzed remote sensing data from MODIS to aid the preparation of the group’s Greenland expedition trip.

· Forecasted sea ice conditions in the expedition path to assist the effort in guiding boat operation.

· Established a fast delivery system for forwarding near-real-time data to the research team in the field.

Plankton of Orange County (2013 – 2014)

· Volunteer at the Back Bay Science Center and manage phytoplankton cultures.

· Assisted Prof. Peter J. Bryant (Dept. of Development and Cell Biology, UCI) to conduct microscopy on local plankton species. An effort to compile a natural history inventory of Orange County, California.


Plant Ecology & Physiology | Dept. of Earth System Science, UC Irvine

Abstract: Nitrogen (N) is essential for protein and chlorophyll formation; thus, N deficiency could result in a loss of plant productivity. A carnivorous species found in the nutrient-poor region of Malay Peninsula, Nepenthes sanguinea, is able to subsidize the soil N supply by consuming insects. This species is also a popular horticultural cultivar.  Although this species is adapted to obtaining N from insects, many nurseries recommend small amounts of nitrogen fertilization, while others recommend no fertilization. There has been very little research on the N dynamics of carnivorous plants, and we currently do not have a clear understanding of preferred N sources of N. sanguinea, or how different N sources affect the growth of carnivorous plant species. To improve our understanding of the N dynamics of N. sanguinea, we set up a factorial experiment in which different groups received insect prey and/or inorganic N fertilizer. We utilized natural abundance N isotopes to determine the amount of plant N derived from each source. We found that plants that received no insects and no fertilizer had very low concentrations of leaf N.  However, leaf N in plants that received insects was unaffected by the addition of fertilizer.  In addition, plants that received insects were very enriched in N isotopes, indicating uptake of insect-derived N. The measurements of biomass suggest that insect-derived N increased plant growth more than fertilizer-derived N. This information will improve the current cultivation methods of Nepenthes, and help growers to produce fully developed plants. 

Measuring leaf conductance. 

UROP Symposiums Presentation “The linkage between native habitat and plant water use in acacia species” 2010

Abstract: When leaf stomates are open, CO2 is taken up for photosynthesis and water is lost through transpiration.  The amount of CO2 fixed in photosynthesis per unit water lost in transpiration is the plant Water Use Efficiency (WUE).  WUE varies among species and is an important determinant for selecting plants that grow efficiently with minimal water inputs.  We do not currently have a means of predicting WUE; however, it is generally assumed that species originating in more arid ecosystems will use less water and will have greater WUE.  To test this hypothesis, we investigated the linkage between plant water use efficiency and native ecosystem in 14 common horticultural shrub and tree species within the genus Acacia.  All species were grown in an irrigated common garden environment at the Los Angeles County Arboretum and Botanic Garden.  Plant water use efficiency was determined through carbon isotope analysis of bulk leaves and leaf soluble sugars, and leaf transpiration was measured using a handheld porometer.  Contrary to our hypothesis, Acacia species originating in more arid ecosystems used more water and were less WUE than Acacia species originating in more temperate ecosystems.  The results of this study indicate that under well-watered conditions arid species may use more water than temperate species.  Given the growing importance of water conservation in southern California, an improved understanding of water use in horticultural plants will provide critical information for selecting water efficient plants and determining plant irrigation needs. 

UCI COSMOS Program (2008)