INSPIRE: Investigating the Role of Mesoscale Processes and Ice Dynamics in Carbon and Iron Fluxes in a Changing Amundsen Sea

Simulated surface chlorophyll in the Amundsen Sea Polynya (OPP-1443657) and sea ice from NSIDC/MODIS

Figure 1: The Amundsen Sea in Dec.2010 (Austral summer). Green shading is the surface chlorophyll from numerical simulations conducted at Old Dominion University (OPP-1443657) and represents algae growing inside ice-free regions (aka "polynyas"). Gray background represents sea ice (ice floating at surface of water) and glacial ice (part of the Antarctic ice sheet) from a satellite (MODIS/NSIDC). North is upward in the figure. ASP: Amundsen Sea Polynya. DIS: Dotson Ice Shelf. CIS: Crosson Ice Shelf. TLT: Thwaites Landfast ice Tongue. B-22A: Large iceberg that calved from the TGT. TGT: Thwaites Glacier Tongue. TIS: Thwaites Ice Shelf. PIP: Pine Island Polynya. PIG: Pine Island Glacier.

What is INSPIRE?

This NSF-funded project (PLR-1443657) unites independent, state-of-the-art modeling and field data synthesis efforts to address important unanswered questions about carbon fluxes and iron supply in a key region of the coastal Antarctic. The Amundsen Sea Polynya (ASP), in the remote South Pacific sector of the Southern Ocean, features 1) large intrusions of modified Circumpolar Deep Water (mCDW) onto the continental shelf, 2) the fastest melting ice shelves in Antarctica, 3) the most productive coastal polynya (161 g C/m2) and a large atmospheric CO2 sink, and 4) some of the most rapid declines in seasonal sea ice on Earth. Following on the heels of a highly successful oceanographic field program, the Amundsen Sea Polynya International Research Expedition (ASPIRE; which sampled the ASP with high spatial resolution during the onset of the enormous phytoplankton bloom of 2011 [1]), the project represents a collaboration between ASPIRE senior scientists and an experienced team of physical and a biogeochemical modelers who can use ASPIRE field data to both validate and extend the capabilities of an existing Regional Ocean Modeling System (ROMS, [2]) for the Amundsen Sea [3]. This new effort will add biology and biogeochemistry (including features potentially unique to the ASP region) to an existing physical model, allowing us to address key questions about bloom mechanisms that could not be answered by field campaigns or modeling alone. This project is expected to generate new insights and hypotheses that will ultimately guide sampling strategies of future field efforts investigating how present and future climate change impacts this important region of the world.

This project addresses two main categories of NSF's Merit Review Broader Impacts Criterion: 1) "improved STEM education and educator development" and 2) "development of a diverse, globally competitive STEM workforce". Advanced pedagogical techniques will be used to provide educational outreach for three distinct target populations: secondary students, pre­service science teachers, and in­service science teachers. Partnerships will be developed with science teacher educators to implement the STEM career­development lessons in undergraduate and graduate level science teacher education courses. The project also supports graduate education and includes a mentoring plan for an early career scientist supported by the project (St-Laurent, lead PI, who obtained his Ph.D. in 2010). Senior members of the team will meet with St-Laurent once a month virtually and twice a year in person to provide scientific and technical supervision. This is an important step in his development as an independent scientist.

Contributors

INSPIRE is a collaborative effort between East Carolina University (ECU), Old Dominion University (ODU), Rutgers University, University of Colorado and University of Georgia (UGA). The project involves D.Dickerson (ECU), M.Dinniman, E.Hofmann and P.St-Laurent (ODU), R.Sherrell (Rutgers), S.Stammerjohn (U.Col.), and P.Yager (UGA).
Please contact P.St-Laurent (pstlaure@odu.edu) for inquiries about the project.

Acknowledgment and Disclaimer

This material on this web page is based upon work supported by the National Science Foundation under Grant Number 1443657. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

The Amundsen Sea

Maps of the Southern Ocean and the Amundsen Sea

Figure 2: (a) Summer chlorophyll climatology for 2002-2013 (shading) in the Southern Ocean (GSFC 2014a) showing higher concentrations on the continental shelves (the scale saturates at 3 mg/m3. The black box is the Amundsen Sea (AS). The Antarctic Circumpolar Current (ACC, black arrow) is bounded by the Sub-Antarctic Front (SAF, outer black line) and the Southern Boundary of the ACC (SBACC, Orsi et al. 1995, inner black line). (b) The Amundsen Sea Model (ASM, St-Laurent et al. 2015) domain with the main ice shelves labeled. The Amundsen Sea Polynya (ASP) is represented with the climatological 15% sea ice concentration line for the month of January (red contour line; from AMSR-E). GIS is Getz Ice Shelf, DIS is Dotson Ice Shelf, CIS is Crosson Ice Shelf, TGT is Thwaites Glacier Tongue, TIS is Thwaites Ice Shelf, PIG is Pine Island Glacier, TIT, is Thwaites Iceberg Tongue, TLT is Thwaites Landfast Tongue, DT is Dotson Trough, CT is Central Trough, MBB is Mid-Bay Bank, ET is Eastern Trough. The topography is from Millan et al. [4] and from RTopo-2.0.1 [5]. The model horizontal resolution is 1.5 km everywhere over the domain to explicitly resolve the mesoscales.


Figure 3: Simulated conditions at the onset of the algal bloom (Nov.1, 2010; year of the ASPIRE cruise). (Top left) Sea ice concentration, (Top right) surface nitrate concentration, (Bottom left) surface particulate organic nitrogen concentration, (Bottom right) surface dissolved iron concentration. For best results, download the video (.ogv, .mp4) and play it from your device.

Bottom concentration of tracer representing CDW
Figure 4: Numerical tracer representing Circumpolar Deep Water (CDW) intruding over the continental shelf of the Amundsen Sea (Right-click on this link and select "Save File As" to download a video). The tracer is initialized to 1000ppt offshelf where potential temperatures are greater than 0.7C. The video illustrates the pathways and timescales associated with the circulation of CDW (and its associated iron) on the shelf. The model topography is from Millan et al. [4] and RTopo-2.0.1 [5].

Simulated bottom ocean temperature and ice shelf basal melt
Figure 5: Simulated bottom ocean temperature and ice shelf basal melt. Temperature is for Dec.2013 while the basal melt represents an average over years 2006-2013. The model topography is from Millan et al. [4] and RTopo-2.0.1 [5]. The main ice shelves are labeled.

Educational booklet developed for the INSPIRE project
Figure 6: Extract from the educational booklet developed in collaboration with local artists and STEM educators (Carl Twarog being the illustrator). The booklet is being implemented in schools and its efficiency evaluated by STEM specialist D.Dickerson.

Cover image of research feature on Patricia Yager and the INSPIRE project
Figure 7: The magazine Research Features recently interviewed co-PI Patricia Yager about the INSPIRE project. This led to an article communicating the project's goals and results to a general audience.

Presentations and manuscripts

Presentations, manuscripts and datasets from/related to INSPIRE:

References

  1. Yager, P.L., R. M. Sherrell, S. E. Stammerjohn, A.-C. Alderkamp, O. Schofield, E. P. Abrahamsen, K. R. Arrigo, S. Bertilsson, D. L. Garay, R. Guerrero, K. E. Lowry, P.-O. Moksnes, K. Ndungu, A. F. Post, E. Randall-Goodwin, L. Riemann, S. Severmann, S. Thatje, G. L. van Dijken and S. Wilson, 2012. ASPIRE: The Amundsen Sea Polynya International Research Expedition, Oceanography, vol.25(3) p.40-53, doi:10.5670/oceanog.2012.73.
  2. Shchepetkin, A. F. and J. C. McWilliams, 2005. The Regional Oceanic Modeling System (ROMS): A split-explicit, free-surface, topography-following-coordinate oceanic model, Ocean Modelling, vol.9, p.347-404, doi:10.1016/j.ocemod.2004.08.002.
  3. St-Laurent, P., J. Klinck, and M. Dinniman, 2015. Impact of local winter cooling on the melt of Pine Island Glacier, Antarctica, J. Geophys. Res., vol.120(10), p.6718-6732, doi:10.1002/2015jc010709, preprint.
  4. Millan, R., E. Rignot, V. Bernier, M. Morlighem and P. Dutrieux, 2017. Bathymetry of the Amundsen Sea Embayment sector of West Antarctica from Operation IceBridge gravity and other data, Geophys. Res. Lett., doi:10.1002/2016GL072071.
  5. Schaffer, J., R. Timmermann, J.E. Arndt, S.S. Kristensen, C. Mayer, M. Morlighem and D. Steinhage, 2016. A global, high-resolution data set of ice sheet topography, cavity geometry, and ocean bathymetry. Earth System Science Data, 8(2), 543-557, doi:10.5194/essd-8-543-2016
  6. Powers, J. G., K. W. Manning, D. H. Bromwich, J. J. Cassano and A. M. Cayette, 2012. A decade of Antarctic science support through AMPS, Bulletin of the American Meteorological Society, November, p.1699-1712, doi:10.1175/bams-d-11-00186.1
  7. Mazloff, M.R., P. Heimbach, and C. Wunsch, 2010. An eddy-permitting Southern Ocean State Estimate. J. Phys. Oceanogr., vol.40(5), doi:10.1175/2009jpo4236.1.