A5024837964- Marine and coastal ecosystems
- Oceanographic and Atmospheric Processes
- Climate variability and models
- Meteorological Phenomena and Simulations
- Atmospheric and Environmental Gas Dynamics
- Ocean Acidification Effects and Responses
- Reservoir Engineering and Simulation Methods
- Microbial Community Ecology and Physiology
- Statistical Methods and Bayesian Inference
- Marine Biology and Ecology Research
- Hydrological Forecasting Using AI
- Target Tracking and Data Fusion in Sensor Networks
- Neural Networks and Applications
- Radioactivity and Radon Measurements
- Fault Detection and Control Systems
- Geological Modeling and Analysis
- Soil and Water Nutrient Dynamics
- Groundwater and Isotope Geochemistry
- Coastal wetland ecosystem dynamics
- CO2 Sequestration and Geologic Interactions
- Arctic and Antarctic ice dynamics
- Hydrocarbon exploration and reservoir analysis
- Coastal and Marine Dynamics
- Geology and Paleoclimatology Research
- Archaeology and ancient environmental studies
University of California, Santa Cruz
2014-2024
Dalhousie University
2009-2015
We present a user‐friendly and versatile Monte Carlo simulator for modeling profiles of in situ terrestrial cosmogenic nuclides (TCNs). Our program (available online at http://geochronology.earthsciences.dal.ca/downloads‐models.html ) permits the incorporation site‐specific geologic knowledge to calculate most probable values exposure age, erosion rate, inherited nuclide concentration while providing rigorous treatment their uncertainties. The is demonstrated with 10 Be data from fluvial...
Abstract. The deliberate increase of ocean alkalinity (referred to as Ocean Alkalinity Enhancement or OAE) has been proposed a method for removing CO2 from the atmosphere. Before OAE can be implemented safely, efficiently, and at scale several research questions have addressed including: 1) which alkaline feedstocks are best suited in what doses they added 2) how net carbon uptake measured verified, 3) potential ecosystem impacts. These cannot by direct observation alone but will require...
We assimilate satellite observations of surface chlorophyll into a three‐dimensional biological ocean model in order to improve its state estimates using particle filter referred as sequential importance resampling (SIR). Particle Filters represent an alternative other, more commonly used ensemble‐based estimation techniques like the ensemble Kalman (EnKF). Unlike EnKF, do not require normality assumptions about error structure and are thus suitable for highly nonlinear applications....
Abstract The combination of taxa and size classes phytoplankton that coexist at any location affects the structure marine food web magnitude carbon fluxes to deep ocean. But what controls patterns this community across environmental gradients remains unclear. Here, we focus on North East Pacific Transition Zone, a ~ 10° region latitude straddling warm, nutrient‐poor subtropical cold, nutrient‐rich subpolar gyres. Data from three cruises revealed intricate structure: poleward increases in...
Abstract Numerical ocean models are becoming increasingly important tools for marine research and management of resources. It is therefore crucial that uncertainty in model predictions sensitivity to errors the inputs be quantified. We performed a combined analysis realistic physical‐biological Texas‐Louisiana shelf northern Gulf Mexico. The simulates major physical biological processes involved formation hypoxic zone develops on every summer. With help statistical emulator technique, we...
Abstract A procedure to objectively adjust the error covariance matrices of a variational data assimilation system is presented. It based on popular diagnostics that utilize differences between observations and prior posterior model solutions at observation locations. In application combines three-dimensional, physical–biogeochemical ocean with large datasets physical chlorophyll observations, tuning leads decrease in model-observation misfit small improvements short-term forecasting skill....
<strong class="journal-contentHeaderColor">Abstract.</strong> The deliberate increase in ocean alkalinity (referred to as enhancement, or OAE) has been proposed a method for removing CO<span class="inline-formula"><sub>2</sub></span> from the atmosphere. Before OAE can be implemented safely, efficiently, and at scale several research questions have addressed, including (1)Â which alkaline feedstocks are best suited doses they added (2)Â how net carbon uptake measured verified, (3)Â what...
Abstract Using two emulator‐based procedures, we estimate time‐dependent values for key plankton parameters in a three‐dimensional biogeochemical (BGC) ocean model. The estimation is based on 4 year time series of daily surface satellite chlorophyll observations. estimated display an annual periodicity that can be explained by the succession groups study region. Model simulations using these show improved fit to observations and better forecasting abilities compared with constant optimal...
Satellite observations of the oceans have great potential to improve quality and predictive power numerical ocean models are frequently used in model skill assessment as well data assimilation. In this study we introduce compare various measures for quantitative comparison satellite images output that not been context before. We devised a series test their performance, including sensitivity noise missing values, which ubiquitous images. Our results show two our adapted measures, Adapted Gray...
Dual numbers allow for automatic, exact evaluation of the numerical derivative high-dimensional functions at an arbitrary point with minimal coding effort. We use dual to construct tangent linear and adjoint model code a biogeochemical ocean apply it variational (4D-Var) data assimilation system when coupled realistic physical circulation existing capabilities. The resulting takes modestly longer run than its hand-coded equivalent but is considerably easier implement updates automatically...
Abstract We present a technique that accurately approximates tangent linear and adjoint models for data assimilation applications using only evaluations of the nonlinear model. The approximation offers simple way to create model codes are easily maintainable, as major changes formulation necessitate modifications or code. approach is particularly well suited marine biogeochemical takes advantage typical features these types be computationally viable. illustrate in realistic application,...
The rates of cell growth, division, and carbon loss microbial populations are key parameters for understanding how organisms interact with their environment they contribute to the cycle. However, invasive nature current analytical methods has hindered efforts reliably quantify these parameters. In recent years, size-structured matrix population models (MPMs) have gained popularity estimating division by mechanistically describing changes in size distributions over time. Motivated mechanistic...
Coastal sediments adjacent to urban centers often receive high loads of organic matter (OM) due large nutrient inputs from land that stimulate algae blooms. Early diagenetic models describing the remineralization this OM in have been developed for 50 years. Although these can be applied a range marine sediments, specifying their model parameter values is difficult. In study, one early diagnetic was simulate Osaka Bay, Japan and polynomial chaos expansion (PCE) technique used order choose...
Assimilating biogeochemical (BGC) data into ocean models using traditional four-dimensional variational assimilation (4D-Var) includes the technical challenge of constructing tangent linear (TLM) and adjoint (ADJ) corresponding to non-linear BGC model. This hurdle can be time-consuming, particularly for experiencing active development, with regular updates functional types or representation key processes. We evaluate two alternate approaches that greatly simplify TLM ADJ construction...
Advanced marine ecosystem models can contain more than 100 biogeochemical variables, making data assimilation for these a challenging prospect. Traditional variational techniques like 4dVar rely on tangent linear and adjoint code, which be difficult to create complex with few dozen variables. More recent hybrid ensemble-variational use ensembles of model forecasts produce statistics thus avoid the need or code. We present new implementation four-dimensional ensemble optimal interpolation...