ASOF Achievements 2004 - 2014
ASOF is an international program to study the oceanography, and in particular the fluxes of mass, heat, and freshwater, into and out of the Arctic and subArctic ocean, and their roles in climate variability. A significant achievement of the program was the publication in 2008 of the book “Arctic–Subarctic Ocean Fluxes: Defining the Role of the Northern Seas in Climate” edited by B. Dickson, J. Meincke, and P. Rhines. The ASOF book contains 28 chapters written by over 100 experts and is a notable milestone in high-latitude oceanography. Full details of the ASOF program for the period 2000-2008 appear in the ASOF book.
More recently, the main advances led by ASOF years are as follows:
- ASOF has coordinated a sustained observing array at the Arctic Gateways (Fram, Davis, Bering Straits and the Barents Sea Opening). We now possess roughly a decade of continuous measurements (longer in Bering and Fram Straits). Combined with the various activities in the high Arctic, such as hydrographic surveys, we can now construct a freshwater budget for the Arctic with substantially greater precision. Of particular interest is the fact that the freshwater flux leaving the Arctic has not changed significantly in the last decade. See Haine et al. (2014).
- ASOF has pioneered hydrographic and current measurements in challenging places with new measuring technologies. For example, ASOF researchers made novel measurements in Hudson Strait and Nares Strait. ASOF researchers developed the ability for Seagliders to operate under ice and moorings capable of measuring near-surface hydrography in ice-choked channels (like the IceCycler).
- Similarly, ASOF-coordinated research has explored the dynamics of freshwater export anomalies from the Arctic, where freshwater has been accumulating in recent years. For instance, see Stewart & Haine (2013).
- ASOF has framed research on exchange across the Iceland-Scotland ridge. Specifically, ASOF has provided a broad scientific context and shaped work on both the inflow and outflow to the Nordic Seas east of Iceland. See Olsen et al. (2008), for example.
- Work by ASOF researchers has elucidated the interior pathways of Atlantic water in the Arctic Ocean. See Rudels (2012).
- ASOF has promoted intense two-way interaction between modeling and observational groups working on these issues. This interaction has led both groups to deeper insights. In particular, ASOF observers routinely look beyond their own specific area of interest. And ASOF modelers benefit from understanding in detail the context and limits of observations they use to validate their models. A prominent connection between the ASOF observational and modeling people is the AOMIP/FAMOS initiative, which ASOF supports.
- ASOF researchers have made important discoveries about the flow west of Iceland through Denmark Strait and on the east Greenland shelf. Newly discovered features of the circulation include the East-Greenland Spill Jet, the North Icelandic Jet, and the East Greenland Coastal Current. The research leading to these discoveries is characterized by a mutual interplay of field measurements and high-resolution numerical modeling. See, for example, von Appen et al. (2014), Våge et al. (2011), and Sutherland (2008).
- ASOF has promoted the use of novel oceanographic tracers in the Arctic/subArctic and in numerical models of the region. For example, see Karcher et al. (2012).
- ASOF has facilitated research on increasing heat flux to the subpolar North Atlantic and its impact on Greenland ice sheets (e.g., Straneo & Heimbach, 2013). This work is still in its infancy.
- The ASOF community has regularly contributed to discussions about Arctic/subArctic research priorities and observing strategies. For example, we have produced 4 reports for the Integrated Arctic Ocean Observing System of the Arctic Ocean Sciences Board (AOSB), the Marine Working Group of the International Arctic Science Committee, most recently that by Dickson et al. (2011). More recently, ASOF has promoted other AOSB workshops such as one on mixing process in the Arctic Ocean (Fall 2013) and expected changes in the Arctic Ocean circulation caused by the advent of a seasonal ice cover (ICARPIII workshop, Fall 2014).
- Continued focus on the issues above, especially on the hydrological cycle in the Arctic and sub-polar North Atlantic ocean.
- Greater interaction between field researchers and modelers, to include data assimilation.
- Renewed focus on the downstream impacts of Arctic hydrological changes on the AMOC and on Atlantic ecosystems, in particular.
Dickson, B., B. Rudels, C. Lee, and T. Haine. iAOOS: An ocean-observing system for northern seas during the legacy phase of the International Polar Year. Technical report, Arctic Ocean Sciences Board Marine Working Group, 2011. Haine, T. W. N., B. Curry, R. Gerdes, E. Hansen, M. Karcher, C. Lee, B. Rudels, G. Spreen, L. de Steur, K. D. Stewart, and R. Woodgate. Arctic freshwater export: Status, mechanisms, and prospects. Glob. Planet. Change, submitted, 2014. Available at: pages.jh.edu/~thaine1/Haine_etal_22Jul14.pdf Karcher, M., A. Beszczynska‐Möller, F. Kauker, R. Gerdes, S. Heyen, B. Rudels, U. Schauer, Arctic Ocean warming and its consequences for the Denmark Strait overflow, J. Geophys. Res., 116, doi:10.1029/2010JC006265, 2011. Karcher, M., J. N. Smith, F. Kauker, R. Gerdes, W. M. Smethie, Recent changes in Arctic Ocean circulation revealed by iodine-129 observations and modeling, J. Geophys. Res., 117, 10.1029/2011JC007513, 2012. Olsen, S. M., B. Hansen, D. Quadfasel, and S. Østerhus, Observed and modelled stability of overflow across the Greenland–Scotland ridge, Nature, 455, 519-522, 2008. Rudels, B., Arctic Ocean circulation and variability-advection and external forcing encounter constraints and local processes, Ocean Science, 8, 261-286, 2012. Straneo, F. and P. Heimbach, North Atlantic warming and the retreat of Greenland's outlet glaciers, Nature, 504, 6-43, 10.1038/nature12854, 2013. Stewart, K. D. and T. W. N. Haine. Wind-driven Arctic freshwater anomalies. Geophys. Res. Lett., 40, 10.1002/2013GL058247, 2013. Sutherland, D., The East Greenland Coastal Current: its structure, variability, and large-scale impact, PhD. Thesis, MIT-WHOI Joint program, 2008. Våge, K., R. S. Pickart, M. A. Spall, H. Valdimarsson, S. Jónsson, D. J. Torres, S. Østerhus, and T. Eldevik, Significant role of the North Icelandic Jet in the formation of Denmark Strait overflow water, Nature Geosci., 4, 723–727, 10.1038/ngeo1234, 2011. von Appen, W.-J., I. M. Koszalka, R. S. Pickart, T. W. N. Haine, D. Mastropole, M. G. Magaldi, H. Valdimarsson, J. Girton, K. Jochumsen, and G. Krahmann. The East Greenland Spill Jet as an important component of the Atlantic Meridional Overturning Circulation. Deep Sea Res., Part I, in press, 2014. Available at: pages.jh.edu/~thaine1/vonAppen_etal_preprint.pdf