COMPASS-FME Research Tasks
Task 1: Fundamental mechanisms and processes
This research will develop a mechanistic understanding of the transformations and exchanges of carbon, nutrients, and redox-active elements across coastal TAIs. We use field observations and lab- and field-based experiments to improve fundamental representation in models and test specific hypotheses.
Three types of activities provide spatial, temporal, and mechanistic information about these coastal interfaces:
- EXCHANGE (Exploration of Coastal Hydrobiogeochemistry Across a Network of Gradients and Experiments)
This activity will establish a consortium of collaborators and deploy standardized sampling kits to capture baseline spatial heterogeneity in hydrobiogeochemical properties in the two study regions. These partnerships will reveal the regional variability in system gradients and biogeochemical profiles. To learn how to become a partner, contact coastal.exchange@pnnl.gov.
- Fixed and mobile synoptic sites
This activity will establish a network of 3 fixed synoptic sites per region to characterize how ecosystem structure and function vary with physicochemical conditions. A varying set of mobile sites will be identified and visited in a series of campaigns designed to make measurements through important inundation events. Transects along shorelines and across redox gradients from uplands to the wetland edge at each site will be studied to resolve the interactions among hydrology, soils, and vegetation that occur across coastal TAIs.
- Experiments
Three types of experiments will be used to resolve mechanisms that underpin the transformations and transport of carbon and nutrients across coastal terrestrial aquatic interfaces. Lab incubations of soil and sediment cores, batch experiments, and soil transplant experiments in the field will assess the effects of inundation (with and without salinization) on biogeochemical cycles at our sites.
Task 2: Process coupling across scales
Using multiscale measurements gathered under Task 1 and additional data sources from remote sensing platforms in combination with ML-based algorithms, we will develop new predictive understanding of how dynamics at fine spatial scales influence coastal TAI structure and function at larger spatial scales. Our approach includes data and models in a nested hierarchy of scales, providing a new capability to predict the dynamics of coastal TAIs at scales relevant to the land surface component of a high-resolution ESM.
Three types of activities integrate the knowledge gained as Task 1 proceeds into a predictive framework:
- Coupled Process Modeling and Analyses
This activity will represent interactions among soil, water, and plants in process-resolving TAI models and evaluate how mechanistic TAI models that integrate this continuum of TAI components improve the predictions of carbon and nitrogen transformations and fluxes.
- Data-Model Integration across Scales
In this activity, we will learn the scale dependency of hydrology, vegetation, and soil biogeochemistry by comparing observations, fine-scale modeling results, and gridded model representations across multiple demonstration gridcells spanning a range of coastal TAI types.
- Predicting Future Disturbance Impacts
In this activity, we will use a large-scale field manipulation within our Chesapeake Bay region, “TEMPEST,” to determine the mechanisms and impacts of seawater inundation from a storm surge versus freshwater inundation. ELM-FATES-Hydro will be developed for coastal TAI systems, evaluated against data from Activities 1.1, 1.2, and 2.3 (the field manipulation), and applied to understand the impacts of disturbances on ecosystem structure and function and to identify state change thresholds. This disturbance activity provides a stringent, integrative test of both our mechanistic knowledge and models at all scales.
