INSPIRE: Investigating the Role of Mesoscale Processes and Ice Dynamics in Carbon and Iron Fluxes in a Changing Amundsen Sea
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?
Acknowledgment and Disclaimer
Outcomes of the project
Figures and videos about INSPIRE and the Amundsen Sea
What is INSPIRE?
This NSF-funded project (PLR-1443657) united 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 ), the project represented 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, ) for the Amundsen Sea . This new effort added 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 generated 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.
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.
INSPIRE was a collaborative effort between Old Dominion University (ODU; 1443657), University of Georgia (UGA; 1443604), Rutgers University (1443315) and the University of Colorado (1443569). The project involved P.St-Laurent, M.Dinniman and E.Hofmann at ODU, P.Yager and Hilde Oliver at UGA, R.Sherrell at Rutgers University, S.Stammerjohn at U.Colorado, and D.Dickerson at ECU.
Please contact P.St-Laurent (email@example.com) for inquiries about the project.
Outcomes of the project
Summary for the general public
The INSPIRE project investigated a unique region of the coastal Antarctic (the Amundsen Sea Polynya, ASP) characterized by fast-melting glaciers and a very high production of microscopic algae during the summer season. It helped to undercover the inner workings of this region and to progressively reveal the secrets behind its unusually high productivity. One of the most important outcomes of INSPIRE relates to the circulation of the water in the region. The meltwater from the glaciers was found to act like warm air in a shower, rising toward the surface while pulling in water at the bottom. This ‘meltwater pump’ is amplified by the tremendously high glacier melt rates of the Amundsen Sea and influences the water circulation a hundred miles away from the glaciers. The key effect of this pump is that it pulls in bottom water that is rich in iron, transports it upward, and then releases it close to the surface. Computer simulations (akin to those used for weather forecasts) further revealed that the water that is pumped will accumulate over several years in the ASP.
The accumulation of water that is rich in iron has important implications for marine life. Single-celled algae, the backbone of the marine food web, are often deficient in iron in this region of the World Ocean, which can limit their growth rate and therefore the annual ‘yield’ of the region. The meltwater pump partly alleviates this situation in the ASP and contributes to the region’s productivity. This productivity is eventually limited by another factor; the availability of light. Computer simulations revealed that the algae becomes sufficiently abundant in the ASP to partially block the incident sunlight. Ultimately, it is the limited availability of both light and iron that determines the decline of the algae production at the end of the summer season. With this additional insight on the productivity the ASP, the project investigated the fate of the tremendous amount of organic material produced during the summer bloom. This investigation was innovative because it used a state-of-the-art computer simulation representing simultaneously the melt of the glaciers, the circulation of the water and the biological interactions. The simulation revealed that organic matter is transported by the ocean circulation over a distance of a hundred miles before reaching the sea floor or being recycled. This result expands our understanding of the fate of organic matter in the ASP and represents valuable insight for future field efforts.
The INSPIRE project had multiple beneficial impacts for society at large. The computer simulations developed during the course of INSPIRE are shared with other research groups, notably glaciologists studying the contribution of Antarctic glacial melting to global sea level rise. The latter process directly affects coastal communities throughout the world. Moreover, increasing atmospheric CO2 concentrations affect the environment through global warming and ocean acidification. INSPIRE contributed to our understanding of how the ocean, like forests on land, can potentially slow down the increase in atmospheric CO2 concentrations. The goals and outcomes of INSPIRE were communicated in a variety of formats including a magazine article targeting the general public, a website, and multiple publications and presentations for the scientific community. The results of INSPIRE were also integrated into educational activities by a STEM specialist. The activities introduced the students to important physical/biological concepts of marine life and to STEM-related careers in environmental sciences.
Pathways and supply of dissolved iron in the Amundsen Sea (Antarctica),
St-Laurent, P., P.L. Yager, R.M. Sherrell, S.E. Stammerjohn and M.S. Dinniman,
Journal of Geophysical Research: Oceans, 2017, 122(9), p.7135-7162, https://doi.org/10.1002/2017jc013162 Preprint PDF Supporting information (on journal website)
Ice pumps & Algae (educational booklet),
Twarog, C., P. St-Laurent, E.E. Hofmann, D.L. Dickerson and A.H. Brown,
2017, ISBN 978-0-692-86607-8
St-Laurent, P., Modeling the pathways of oceanic heat and glacial meltwater on the continental shelf of the Amundsen Sea, Antarctica, invited seminar at the Earth System Science department of UC Irvine (host: Eric Rignot), Irvine CA, January 15, 2019.
Oliver, H., P. St-Laurent, R.M. Sherrell, P.L. Yager, Controls on summer phytoplankton blooms in a highly productive Antarctic coastal polynya, Abstract OS34B-06 presented at 2018 AGU Fall Meeting, Washington DC, December 10-14, 2018.
Yager, P.L., P. St-Laurent, H. Oliver, R.M. Sherrell, S.E. Stammerjohn, M.S. Dinniman, High-resolution numerical ocean model illustrates how ice-sheet ocean interactions impact the biological pump of an Antarctic coastal polynya, Abstract C12B-07 presented at 2018 AGU Fall Meeting, Washington DC, Washington DC, December 10-14, 2018.
Schwans, E., B.R. Parizek, R.B. Alley, D. Pollard, M. Morlighem, R.T. Walker, T. LaBirt, H. Seroussi and P. St-Laurent, Ice Sheet System Model (ISSM) studies of controls on stability of Thwaites and Pine Island Glaciers, West Antarctica, Abstract C31C-0515 presented at 2018 AGU Fall Meeting, Washington DC, December 10-14, 2018.
Oliver, H., P. St-Laurent, R.M. Sherrell and P.L. Yager, Controls on marine primary productivity in a coastal polynya receiving large iron inputs from melting West Antarctic ice shelves, presentation at the 2018 WAIS workshop, Stony Point NY, Sep. 16-20, 2018.
Yager, P.L., P. St-Laurent, H. Oliver, R.M. Sherrell, S.E. Stammerjohn and M.S. Dinniman, Hi-res model illustrates how melting ice impacts coastal carbon cycle, presentation at the 2018 WAIS workshop, Stony Point NY, Sep. 16-20, 2018.
Schwans, E., B.R. Parizek, R.B. Alley, D. Pollard, M. Morlighem, H. Seroussi, P. St-Laurent, Bed character of Thwaites Glacier: Implications for stability, presentation at the 2018 WAIS workshop, Stony Point NY, September 16-19, 2018.
Oliver, H., P. St-Laurent, R.M. Sherrell, P.L. Yager, Does light or iron control the Amundsen Sea Polynya phytoplankton bloom?, presentation at the Ocean Carbon and Biogeochemistry Summer Workshop, Woods Hole MA, June 25-28, 2018.
Dinniman, M., P. St-Laurent, K. Arrigo, E. Hofmann, J. Klinck, R.M. Sherrell, S. Stammerjohn and P.L. Yager, Ice shelf meltwater pump contribution to vertical exchange around Antarctica, 2018 SCAR/IASC Open Science Conference, Davos, Switzerland, June 15-26, 2018.
Oliver, H., P. St-Laurent, R.M. Sherrell and P.L. Yager, What controls the massive phytoplankton bloom in the Amundsen Sea Polynya?, presentation at the 2018 Ocean Sciences Meeting, Portland OR, Feb.11-16, 2018.
Dinniman, M.S., P. St-Laurent, K.R. Arrigo, E.E. Hofmann, J.M. Klinck, R.M. Sherrell, S.E. Stammerjohn and P.L. Yager, The ice shelf meltwater pump contribution to vertical exchange over the open shelf in the Amundsen Sea and elsewhere around Antarctica, presentation at the 2018 Ocean Sciences Meeting, Portland OR, Feb.11-16, 2018.
Sherrell, R.M., P.L. Yager, P. St-Laurent, M.S. Dinniman, S.E. Stammerjohn, M. Lagerstrom and K.M. Harazin, High iron in outflow waters from the Dotson Ice Shelf cavity, Amundsen Sea, West Antarctica: Is glacial meltwater really the source?, presentation at the 2018 Ocean Sciences Meeting, Portland OR, Feb.11-16, 2018.
Schwans, E., B. Parizek, M. Morlighem, R.B. Alley, D. Pollard, R.T. Walker, P. Lin, P. St-Laurent, T. LaBirt and H. Seroussi. Simulating ice dynamics in the Amundsen Sea sector, presentation at the 2017 AGU Fall meeting, New Orleans LA, Dec. 11-15, 2017.
Yager, P.L., P. St-Laurent, R.M. Sherrell, M.S. Dinniman and S.E. Stammerjohn, ‘Meltwater pump’ mechanism directly links the extreme Amundsen Sea phytoplankton bloom to the melting ice shelf, presentation at the 2017 WAIS meeting, Coupeville WA, Oct. 8-11, 2017.
Oliver, H., P. St-Laurent, R.M. Sherrell, P.L. Yager, Physical and biological controls on phytoplankton blooms in the Amundsen Sea Polynya, presentation at the 2017 International Goldschmidt Conference, Paris (France), August 13-18, 2017.
St-Laurent, P. and M.S.Dinniman, Ice shelf melt-driven circulation of the deep layers in the Amundsen Sea, Antarctica, poster presentation at the 31st Forum for Research into Ice Shelf Processess (FRISP) workshop, Bergen (Norway), June 19-22, 2017
Dinniman, M.S., P. St-Laurent, E. Hofmann, J.M. Klinck, S. Mack, 2017. How the cryosphere may affect iron supply to Antarctic phytoplankton blooms, The Southern Ocean Workshop: Its dynamics, biogeochemistry and role in the climate system, Boulder CO, April 10-13, 2017.
Sherrell, R., et al., How natural iron fertilization works in productive west Antarctic shelf regions, invited seminar at Lamont-Doherty Earth Observatory, Columbia University, Palisades NY, April 7, 2017
St-Laurent, P. Physical drivers of the highly-productive Amundsen Sea Polynya (Antarctica), invited presentation for the 2017 OEAS Seminar Series, Old Dominion University, Norfolk VA, April 6, 2017.
Oliver, H., P. St-Laurent, R.M. Sherrell and P.L. Yager, 2017. What makes a bloom in the Amundsen Sea Polynya? A 1-D biogeochemical modeling perspective, Gordon Research Conference on Polar Marine Science, Ventura CA, March 26-31, 2017.
St-Laurent, P., M.S. Dinniman, E.E. Hofmann, R.M. Sherrell, S.E. Stammerjohn and P.L. Yager, 2016, Variability of physical parameters influencing the bloom of the most productive Antarctic coastal polynya (Amundsen Sea Polynya), presentation at the 2016 WAIS workshop, Sterling, VA, Oct.3-6, 2016.
Yager, P.L., P. St-Laurent, R.M. Sherrell, H. Oliver, M.S. Dinniman, S.E. Stammerjohn, 2016, Melting ice enhances coastal biological productivity, presentation at the 2016 WAIS workshop, Sterling, VA, Oct.3-6, 2016.
St-Laurent, P., M.S. Dinniman, E.E. Hofmann, R. Sherrell, S. Stammerjohn, P. Yager, and E. Randall-Goodwin, Transport pathways of nutrients in the Amundsen Sea, Antarctica, Oral presentation at the 2016 Ocean Sciences meeting, Feb. 21-26, 2016, New Orleans, Louisiana.
Linquan Mu, Investigating the Role of Mesoscale Processes and Ice Dynamics in Carbon and Iron Fluxes in a Changing Amundsen Sea (INSPIRE), poster presentation at the 2016 Ocean Sciences meeting, Feb. 21-26, 2016, New Orleans, Louisiana.
Yager, P.L, H. Oliver, R. Sherrell, S. Stammerjohn, P. St-Laurent, E. Hofmann, T. Mote, M. Tedesco, A. Rennermalm, R. Castelao, Ice Sheet Meltwater Impacts on Biological Productivity in High-Latitude Coastal Zones - Observations and Model Results for West Antarctica and Southwest Greenland, Abstract 85104 presented at 2015 AGU Fall Meeting, Dec. 14-18, 2015, San Francisco, California.
Yager, P.L., R.M. Sherrell, S.E. Stammerjohn, and P. St-Laurent, Ice sheet meltwater impacts on biological productivity in the Amundsen Sea Polynya region, talk at the 2015 West Antarctic Ice Sheet Initiative (WAIS) workshop, Sep. 16-19, 2015, Sylvan Dale Ranch, Loveland, Colorado.
Figures and videos about INSPIRE 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.  and from RTopo-2.0.1 . 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 (.webm, .ogv, .mp4) and play it from your device.
Figure 4: Numerical tracer representing Circumpolar Deep Water (CDW) intruding over the continental shelf of the Amundsen Sea. A video covering years 2006-2013 is available for download (.webm or .mp4). 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.  and RTopo-2.0.1 .
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.  and RTopo-2.0.1 . The main ice shelves are labeled.
Figure 6: Extract from the educational booklet developed in collaboration with local artists and STEM educators (Carl Twarog being the illustrator). The booklet was used in schools and its efficiency was evaluated by STEM specialist D.Dickerson.
Figure 7: The magazine Research Features 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.
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.
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.
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.
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.
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
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
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.