Noble gases are ideal tracers of gas exchange processes because of their inert nature and varying physical properties. As water cools during deepwater formation it becomes undersaturated. This results in an incomplete influx of gas via air-sea gas exchange, as the water is subducted before it can fully equilibrate. Additionally, breaking waves cause a flux of gas by injecting bubbles into the surface ocean. Measurements of a suite of inert gases in the deep ocean, each with unique physical properties, can provide constraints on the role of cooling, bubbles and other processes on air-sea gas exchange in high latitude deepwater formation regions. We are applying measurements of Ne, Ar, N2, Kr and Xe as geochemical constraints on ocean ventilation processes. We have build a database of published noble gas observations and interpret these data using a hierarchy of ocean models, from simple box models to GCMs. Modeling tools including the Transport Matrix Method and Matrix-Free Newton Krylov allow us to overcome the challenge of deep-ocean spin-up time and enable observations to inversely constrain air-sea flux processes.
University of Oxford: S. Khatiwala
WHOI: R.H.R. Stanley, C.C. Manning
NSF: An Inverse and Forward Modeling Synthesis of Noble Gases to Better Quantify Biogeochemical Cycles
Manning, C.C., R.H.R. Stanley, D.P. Nicholson, J. Smith, J.T. Pennington. M. Fewings, M. Squibb, F. Chavez (2017), Impact of recently upwelled water on productivity investigated using in situ and incubation-based methods in Monterey Bay. J. Geophys. Res., Oceans. 2016JC012306 doi:10.1002/2016JC012306.
Manning, C. C., R. H. R. Stanley, D. P. Nicholson, and M. E. Squibb (2016), Quantifying air-sea gas exchange using noble gases in a coastal upwelling zone, IOP Conf. Ser. Earth Environ. Sci., 35(1), 012017, doi:10.1088/1755-1315/35/1/012017.
Nicholson, D. P., S. Khatiwala, and P. Heimbach (2016), Noble gas tracers of ventilation during deep-water formation in the Weddell Sea, IOP Conf. Ser. Earth Environ. Sci., 35(1), 012019, doi:10.1088/1755-1315/35/1/012019.
Nicholson, D., S. Emerson, S. Khatiwala, R. C. Hamme. (2011) An inverse approach to estimate bubble-mediated air-sea gas flux from inert gas measurements. Proceedings on the 6th International Symposium on Gas Transfer at Water Surfaces. Kyoto University Press.
Nicholson, D., S. Emerson., N. Caillon, J. Jouzel, and R. C. Hamme. (2010) Constraining ventilation during deepwater formation using deep ocean measurements of the dissolved gas ratios N2/Ar, Kr/Ar and δ40Ar. Journal of Geophysical Research – Oceans, C11015, doi:10.1029/2010JC006152.