Articles | Volume 17, issue 21
https://doi.org/10.5194/gmd-17-8049-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/gmd-17-8049-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
An optimal transformation method for inferring ocean tracer sources and sinks
School of Mathematics and Statistics, University of New South Wales, Sydney, Australia
Australian Center for Excellence in Antarctic Science, University of New South Wales, Sydney, Australia
UNSW Data Science Hub (uDASH), University of New South Wales, Sydney, Australia
Taimoor Sohail
School of Mathematics and Statistics, University of New South Wales, Sydney, Australia
Australian Center for Excellence in Antarctic Science, University of New South Wales, Sydney, Australia
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How much heat and freshwater the ocean absorbs is important to understanding climate change. However, our best estimates of heat and freshwater transports into the ocean remain uncertain. In this work, we use a new method called the Optimal Transformation Method (OTM), to reconcile air-sea heat and freshwater transports with ocean temperature and salinity observations, representing a meaningful improvement on existing estimates. Our improved air-sea transport estimates are publicly available.
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How much heat and freshwater the ocean absorbs is important to understanding climate change. However, our best estimates of heat and freshwater transports into the ocean remain uncertain. In this work, we use a new method called the Optimal Transformation Method (OTM), to reconcile air-sea heat and freshwater transports with ocean temperature and salinity observations, representing a meaningful improvement on existing estimates. Our improved air-sea transport estimates are publicly available.
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The ocean absorbs carbon dioxide from the atmosphere, mitigating climate change, but estimates of the uptake do not always agree. There is a need to reconcile these differing estimates and to improve our understanding of ocean carbon uptake. We present a new method for estimating ocean carbon uptake and test it with model data. The method effectively diagnoses the ocean carbon uptake from limited data and therefore shows promise for reconciling different observational estimates.
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Cited articles
Bentamy, A., Piollé, J., Grouazel, A., Danielson, R., Gulev, S., Paul, F., Azelmat, H., Mathieu, P., von Schuckmann, K., Sathyendranath, S., Evers-King, H., Esau, I., Johannessen, J., Clayson, C., Pinker, R., Grodsky, S., Bourassa, M., Smith, S., Haines, K., Valdivieso, M., Merchant, C., Chapron, B., Anderson, A., Hollmann, R., and Josey, S.: Review and assessment of latent and sensible heat flux accuracy over the global oceans, Remote Sens. Environ., 201, 196–218, https://doi.org/10.1016/j.rse.2017.08.016, 2017. a
Bi, D., Dix, M., Marsland, S., O'Farrell, S., Sullivan, A., Bodman, R., Law, R., Harman, I., Srbinovsky, J., Rashid, H. A., Dobrohotoff, P., Mackallah, C., Yan, H., Hirst, A., Savita, A., Dias, F. B., Woodhouse, M., Fiedler, R., and Heerdegen, A.: Configuration and spin-up of ACCESS-CM2, the new generation Australian Community Climate and Earth System Simulator Coupled Model, Journal of Southern Hemisphere Earth Systems Science, 70, 225–251, https://doi.org/10.1071/es19040, 2020. a
Chaudhuri, A. H., Ponte, R. M., Forget, G., and Heimbach, P.: A Comparison of Atmospheric Reanalysis Surface Products over the Ocean and Implications for Uncertainties in Air–Sea Boundary Forcing, J. Climate, 26, 153–170, https://doi.org/10.1175/jcli-d-12-00090.1, 2013. a
Drijfhout, S. S., Blaker, A. T., Josey, S. A., Nurser, A., Sinha, B., and Balmaseda, M.: Surface warming hiatus caused by increased heat uptake across multiple ocean basins, Geophys. Res. Lett., 41, 7868–7874, 2014. a
Durack, P. J., Wijffels, S. E., and Matear, R. J.: Ocean salinities reveal strong global water cycle intensification during 1950 to 2000, Science, 336, 455–458, 2012. a
Evans, D. G., Toole, J., Forget, G., Zika, J. D., Naveira Garabato, A. C., Nurser, A. G., and Yu, L.: Recent wind-driven variability in Atlantic water mass distribution and meridional overturning circulation, J. Phys. Oceanogr., 47, 633–647, 2017. a
Forget, G., Campin, J.-M., Heimbach, P., Hill, C. N., Ponte, R. M., and Wunsch, C.: ECCO version 4: an integrated framework for non-linear inverse modeling and global ocean state estimation, Geosci. Model Dev., 8, 3071–3104, https://doi.org/10.5194/gmd-8-3071-2015, 2015. a
Friedlingstein, P., O'Sullivan, M., Jones, M. W., Andrew, R. M., Gregor, L., Hauck, J., Le Quéré, C., Luijkx, I. T., Olsen, A., Peters, G. P., Peters, W., Pongratz, J., Schwingshackl, C., Sitch, S., Canadell, J. G., Ciais, P., Jackson, R. B., Alin, S. R., Alkama, R., Arneth, A., Arora, V. K., Bates, N. R., Becker, M., Bellouin, N., Bittig, H. C., Bopp, L., Chevallier, F., Chini, L. P., Cronin, M., Evans, W., Falk, S., Feely, R. A., Gasser, T., Gehlen, M., Gkritzalis, T., Gloege, L., Grassi, G., Gruber, N., Gürses, Ö., Harris, I., Hefner, M., Houghton, R. A., Hurtt, G. C., Iida, Y., Ilyina, T., Jain, A. K., Jersild, A., Kadono, K., Kato, E., Kennedy, D., Klein Goldewijk, K., Knauer, J., Korsbakken, J. I., Landschützer, P., Lefèvre, N., Lindsay, K., Liu, J., Liu, Z., Marland, G., Mayot, N., McGrath, M. J., Metzl, N., Monacci, N. M., Munro, D. R., Nakaoka, S.-I., Niwa, Y., O'Brien, K., Ono, T., Palmer, P. I., Pan, N., Pierrot, D., Pocock, K., Poulter, B., Resplandy, L., Robertson, E., Rödenbeck, C., Rodriguez, C., Rosan, T. M., Schwinger, J., Séférian, R., Shutler, J. D., Skjelvan, I., Steinhoff, T., Sun, Q., Sutton, A. J., Sweeney, C., Takao, S., Tanhua, T., Tans, P. P., Tian, X., Tian, H., Tilbrook, B., Tsujino, H., Tubiello, F., van der Werf, G. R., Walker, A. P., Wanninkhof, R., Whitehead, C., Willstrand Wranne, A., Wright, R., Yuan, W., Yue, C., Yue, X., Zaehle, S., Zeng, J., and Zheng, B.: Global Carbon Budget 2022, Earth Syst. Sci. Data, 14, 4811–4900, https://doi.org/10.5194/essd-14-4811-2022, 2022. a, b
Gebbie, G. and Huybers, P.: Total matrix intercomparison: A method for determining the geometry of water-mass pathways, J. Phys. Oceanogr., 40, 1710–1728, 2010. a
Good, S. A., Martin, M. J., and Rayner, N. A.: EN4: Quality controlled ocean temperature and salinity profiles and monthly objective analyses with uncertainty estimates, J. Geophys. Res.-Oceans, 118, 6704–6716, 2013. a
Griffies, S. M., Biastoch, A., Böning, C., Bryan, F., Danabasoglu, G., Chassignet, E. P., England, M. H., Gerdes, R., Haak, H., Hallberg, R. W., Hazeleger, W., Jungclaus, J., Large, W. G., Madec, G., Pirani, A., Samuels, B. L., Scheinert, M., Gupta, A. S., Severijns, C. A., Simmons, H. L., Treguier, A. M., Winton, M., Yeager, S., and Yin, J.: Coordinated Ocean-ice Reference Experiments (COREs), Ocean Model., 26, 1–46, 2009. a
Grist, J. P., Josey, S. A., Zika, J. D., Evans, D. G., and Skliris, N.: Assessing recent air-sea freshwater flux changes using a surface temperature-salinity space framework, J. Geophys. Res.-Oceans, 121, 8787–8806, 2016. a
Groeskamp, S., Zika, J. D., McDougall, T. J., Sloyan, B. M., and Laliberté, F.: The representation of ocean circulation and variability in thermodynamic coordinates, J. Phys. Oceanogr., 44, 1735–1750, 2014a. a
Groeskamp, S., Griffies, S. M., Iudicone, D., Marsh, R., Nurser, A. G., and Zika, J. D.: The water mass transformation framework for ocean physics and biogeochemistry, Annu. Rev. Marine Sci., 11, 271–305, 2019. a
Haine, T. W. and Hall, T. M.: A generalized transport theory: Water-mass composition and age, J. Phys. Oceanogr., 32, 1932–1946, 2002. a
Hersbach, H., Bell, B., Berrisford, P., Hirahara, S., Horányi, A., Muñoz‐Sabater, J., Nicolas, J., Peubey, C., Radu, R., Schepers, D., Simmons, A., Soci, C., Abdalla, S., Abellan, X., Balsamo, G., Bechtold, P., Biavati, G., Bidlot, J., Bonavita, M., Chiara, G., Dahlgren, P., Dee, D., Diamantakis, M., Dragani, R., Flemming, J., Forbes, R., Fuentes, M., Geer, A., Haimberger, L., Healy, S., Hogan, R. J., Hólm, E., Janisková, M., Keeley, S., Laloyaux, P., Lopez, P., Lupu, C., Radnoti, G., Rosnay, P., Rozum, I., Vamborg, F., Villaume, S., and Thépaut, J.: The ERA5 global reanalysis, Q. J. Roy. Meteor. Soc., 146, 1999–2049, https://doi.org/10.1002/qj.3803, 2020. a
Huguenin, M. F., Holmes, R. M., and England, M. H.: Drivers and distribution of global ocean heat uptake over the last half century, Nat. Commun., 13, 4921, 2022. a
Irving, D., Hobbs, W., Church, J., and Zika, J.: A Mass and Energy Conservation Analysis of Drift in the CMIP6 Ensemble, J. Climate, 34, 3157–3170, https://doi.org/10.1175/jcli-d-20-0281.1, 2020. a, b
Josey, S. A., Grist, J. P., and Marsh, R.: Estimates of meridional overturning circulation variability in the North Atlantic from surface density flux fields, J. Geophys. Res.-Oceans, 114, C09022, https://doi.org/10.1029/2008JC005230, 2009. a
Khatiwala, S.: A computational framework for simulation of biogeochemical tracers in the ocean, Global Biogeochem. Cycles, 21, GB3001, https://doi.org/10.1029/2007GB002923, 2007. a
Mackallah, C., Chamberlain, M. A., Law, R. M., Dix, M., Ziehn, T., Bi, D., Bodman, R., Brown, J. R., Dobrohotoff, P., Druken, K., Evans, B., Harman, I. N., Hayashida, H., Holmes, R., Kiss, A. E., Lenton, A., Liu, Y., Marsland, S., Meissner, K., Menviel, L., O'Farrell, S., Rashid, H. A., Ridzwan, S., Savita, A., Srbinovsky, J., Sullivan, A., Trenham, C., Vohralik, P. F., Wang, Y.-P., Williams, G., Woodhouse, M. T., and Yeung, N.: ACCESS datasets for CMIP6: methodology and idealised experiments, Journal of Southern Hemisphere Earth Systems Science, 72, 93–116, https://doi.org/10.1071/es21031, 2022. a
Mikaloff Fletcher, S. E., Gruber, N., Jacobson, A. R., Doney, S. C., Dutkiewicz, S., Gerber, M., Follows, M., Joos, F., Lindsay, K., Menemenlis, D., Mouchet, A., Müller, S. A., and Sarmiento, J. L.: Inverse estimates of anthropogenic CO2 uptake, transport, and storage by the ocean, Global Biogeochem. Cycles, 20, GB2002, https://doi.org/10.1029/2005GB002530, 2006. a
Newsom, E., Zanna, L., Khatiwala, S., and Gregory, J. M.: The influence of warming patterns on passive ocean heat uptake, Geophys. Res. Lett., 47, e2020GL088429, https://doi.org/10.1029/2020GL088429, 2020. a
Skliris, N., Zika, J. D., Nurser, G., Josey, S. A., and Marsh, R.: Global water cycle amplifying at less than the Clausius-Clapeyron rate, Sci. Rep., 6, 38752, https://doi.org/10.1038/srep38752, 2016. a, b
Sohail, T., Irving, D. B., Zika, J. D., Holmes, R. M., and Church, J. A.: Fifty year trends in global ocean heat content traced to surface heat fluxes in the sub-polar ocean, Geophys. Res. Lett., 48, e2020GL091439, https://doi.org/10.1029/2020GL091439, 2021. a, b, c
Sohail, T., Holmes, R. M., and Zika, J. D.: Watermass Co-Ordinates Isolate the Historical Ocean Warming Signal, J. Climate, 36, 1–40, https://doi.org/10.1175/jcli-d-22-0363.1, 2023. a, b
Stammer, D., Martins, M. S., Köhler, J., and Köhl, A.: How well do we know ocean salinity and its changes?, Prog. Oceanogr., 190, 102478, https://doi.org/10.1016/j.pocean.2020.102478, 2021. a
Tomczak, M.: A multi-parameter extension of temperature/salinity diagram techniques for the analysis of non-isopycnal mixing, Prog. Oceanogr., 10, 147–171, https://doi.org/10.1016/0079-6611(81)90010-0, 1981. a
Valdivieso, M., Haines, K., Balmaseda, M., Chang, Y.-S., Drevillon, M., Ferry, N., Fujii, Y., Köhl, A., Storto, A., Toyoda, T., Wang, X., Waters, J., Xue, Y., Yin, Y., Barnier, B., Hernandez, F., Kumar, A., Lee, T., Masina, S., and Peterson, K. A.: An assessment of air–sea heat fluxes from ocean and coupled reanalyses, Clim. Dynam., 49, 983–1008, https://doi.org/10.1007/s00382-015-2843-3, 2017. a, b
Wu, Q. and Gregory, J. M.: Estimating ocean heat uptake using boundary Green's functions: A perfect-model test of the method, J. Adv. Model. Earth Sy., 14, e2022MS002999, https://doi.org/10.1029/2022MS002999, 2022. a
Wunsch, C.: The North Atlantic general circulation west of 50∘W determined by inverse methods, Rev. Geophys. Space Phys., 16, 583–620, 1978. a
Wunsch, C.: Discrete inverse and state estimation problems with geophysical fluid applications, Cambridge University Press,, 2006. a
Wunsch, C. and Heimbach, P.: Practical global oceanic state estimation, Physica D, 230, 197–208, https://doi.org/10.1016/j.physd.2006.09.040, 2007. a
Zika, J. D. and Sohail, T.: An Optimal Transformation Method for inferring tracer sources and sinks, Zenodo [code and data set], https://doi.org/10.5281/zenodo.8008630, 2023. a
Zika, J. D., McDougall, T. J., and Sloyan, B. M.: A tracer-contour inverse method for estimating ocean circulation and mixing, J. Phys. Oceanogr., 40, 26–47, 2009. a
Zika, J. D., England, M. H., and Sijp, W. P.: The Ocean Circulation in Thermohaline Coordinates, J. Phys. Oceanogr., 2, 708–724, https://doi.org/10.1175/JPO-D-11-0139.1, 2012. a
Zika, J. D., Laliberté, F., Mudryk, L. R., Sijp, W. P., and Nurser, A.: Changes in ocean vertical heat transport with global warming, Geophys. Res. Lett., 42, 4940–4948, 2015a. a
Zika, J. D., Skliris, N., Nurser, A. G., Josey, S. A., Mudryk, L., Laliberté, F., and Marsh, R.: Maintenance and broadening of the ocean's salinity distribution by the water cycle, J. Climate, 28, 9550–9560, 2015b. a
Short summary
We describe a method to relate fluxes of heat and freshwater at the sea surface to the resulting distribution of seawater among categories such as warm and salty or cold and salty. The method exploits the laws that govern how heat and salt change when water mixes. The method will allow the climate community to improve estimates of how much heat the ocean is absorbing and how rainfall and evaporation are changing across the globe.
We describe a method to relate fluxes of heat and freshwater at the sea surface to the resulting...