Implementation of FAIR principles in the IPCC: the WGI AR6 Atlas repository.

The Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) has adopted the FAIR Guiding Principles. We present the Atlas chapter of Working Group I (WGI) as a test case. We describe the application of the FAIR principles in the Atlas, the challenges faced during its implementation, and those that remain for the future. We introduce the open source repository resulting from this process, including coding (e.g., annotated Jupyter notebooks), data provenance, and some aggregated datasets used in some figures in the Atlas chapter and its interactive companion (the Interactive Atlas), open to scrutiny by the scientific community and the general public. We describe the informal pilot review conducted on this repository to gather recommendations that led to significant improvements. Finally, a working example illustrates the re-use of the repository resources to produce customized regional information, extending the Interactive Atlas products and running the code interactively in a web browser using Jupyter notebooks.

Surface Water CO2 variability in the Gulf of Mexico (1996-2017).

Approximately 380,000 underway measurements of sea surface salinity, temperature, and carbon dioxide (CO2) in the Gulf of Mexico (GoM) were compiled from the Surface Ocean CO2 Atlas (SOCAT) to provide a comprehensive observational analysis of spatiotemporal CO2 dynamics from 1996 to 2017. An empirical orthogonal function (EOF) was used to derive the main drivers of spatial and temporal variability in the dataset. In open and coastal waters, drivers were identified as a biological component linked to riverine water, and temperature seasonality. Air-sea flux estimates indicate the GoM open (- 0.06 ± 0.45 mol C m-2 year-1) and coastal (- 0.03 ± 1.83 mol C m-2 year-1) ocean are approximately neutral in terms of an annual source or sink for atmospheric CO2. Surface water pCO2 in the northwest and southeast GoM open ocean is increasing (1.63 ± 0.63 µatm  year-1 and 1.70 ± 0.14 µatm year-1, respectively) at rates comparable to those measured at long-term ocean time-series stations. The average annual increase in coastal CO2 was 3.20 ± 1.47 µatm year-1 for the northwestern GoM and 2.35 ± 0.82 µatm year-1 for the west Florida Shelf. However, surface CO2 in the central (coastal and open) GoM, which is influenced by Mississippi and Atchafalaya River outflow, remained fairly stable over this time period.

Deepwater Horizon Oil could have naturally reached Texas beaches.

Following the Deepwater Horizon (DWH) spill, oil residues were found in all five Gulf states of the United States (Texas, Louisiana, Mississippi, Alabama and Florida). However, only a small amount was found in Texas, leading to speculation that it may have arrived there via ship through bilge water instead of naturally via currents. We report on a numerical modeling effort to simulate surface drifters during and after the DWH spill to demonstrate that surface water parcels - and therefore oil carried by those parcels - could reasonably have reached Texas waters at the appropriate time and location from known oiled locations without human interference. We additionally give context for the conditions in 2010 through a study of summer connectivity with the Galveston Bay coastline, which shows that in some years oil from the DWH pipe likely would not have reached Texas.

Tidal eddies at a narrow channel inlet in operational oil spill models.

In operational oil spill modeling, hydrodynamic models often employ a coarse-resolution grid for computational efficiency. However, this practical grid resolution poorly resolves small-scale flow features, such as starting jet vortices (tidal eddies) that are common at the inlet of bar-built estuaries with narrow inlet channels, particularly where channel dredging and jetties have been employed to aid ship traffic. These eddies influence Lagrangian transport paths and hence the fate of an oil spill potentially entering or leaving an estuary. This research quantifies the effect of tidal eddies on the mixing process and effects at model scales relevant to the operational prediction of oil spills, using the Galveston Bay entrance channel as a study site. Model grid sensitivity was analyzed, yielding an adequate eddy solution at the horizontal grid size of ∼140 m. It is demonstrated that the SUNTANS model at a practical operational grid resolution (∼400 m) captures neither the eddies nor their effects on particle movement, despite showing a satisfactory prediction of net transport through the inlet. The need for subgrid eddy modeling is discussed, and an empirical approach is proposed that can improve oil spill predictions at operational grid resolution scales when results from a high-resolution model are available.

Texas and Louisiana coastal vulnerability and shelf connectivity.

A numerical study of connectivity between the continental shelf and coast in the northwestern Gulf of Mexico using a circulation model and surface-limited numerical drifters shows that despite seasonal changes in winds, the overall connectivity of the shelf with the coastline is similar in the winter and summer, though it extends more offshore in Texas in summer. However, there is a spatial pattern to the connectivity: more of the inner shelf is connected with the coast in Texas as compared with Louisiana. Subsets of the coast do have seasonal variability: the coast near both Galveston and Port Aransas has more connectivity from upcoast in the winter and from offshore and downcoast in the summer. In both seasons, we find drifters reach the Port Aransas coast most frequently, with a stronger trend in the summer. These results are important for assessing likely pathways for spilled oil and other potentially hazardous material.

The tarballs on Texas beaches following the 2014 Texas City "Y" Spill: Modeling, chemical, and microbiological studies.

We modeled the transport of oil, source-fingerprinted 44 tarball samples from Galveston Island (GV) and Mustang Island (MT), and determined the hydrocarbon and bacterial community composition of these tarballs following the 2014 Texas City "Y" Oil Spill (TCY). Transport modeling indicated that the tarballs arrived in MT before the samples were collected. Source-fingerprinting confirmed that the tarballs collected from GV and MT, 6d and 11d after the TCY, respectively, originated from the spill. Tarballs from GV showed 21% depletion of alkanes, mainly C9-C17, and 55% depletion of PAHs mainly naphthalenes, and dominated by alkane-degrading Alcanivorax and Psychrobacter. Samples from MT were depleted of 24% alkanes and 63% PAHs, and contained mainly of PAH-degrading Pseudoalteromonas. To the best of our knowledge, this is the first study to relate oil transport, tarball source-fingerprinting, chemistry, and microbiology, which provides insights on the fate of oil in the northern Gulf of Mexico.