Abstract
Solar radiation penetration in the upper ocean is strongly modulated by phytoplankton, which impacts the upper ocean temperature structure, especially in the regions abundant with phytoplankton. In the paper, a new solar radiation penetration scheme, based on the concentration of chlorophyll-a, was introduced into the LASG/IAP (State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics/Institute of Atmospheric Physics) Climate system Ocean Model (LICOM). By comparing the simulations using this new scheme with those using the old scheme that included the constant e-folding attenuation depths in LICOM, it was found that the sea surface temperature (SST) and circulation in the central and eastern equatorial Pacific were both sensitive to the amount of phytoplankton present. Distinct from other regions, the increase of chlorophyll-a concentration would lead to SST decrease in the central and eastern equatorial Pacific. The higher chlorophyll-a concentration at the equator in comparison to the off-equator regions can enlarge the subsurface temperature gradient, which in turn strengthens the upper current near the equator and induces an enhancing upwelling. The enhancing upwelling can then lead to a decrease in the SST in the central and eastern equatorial Pacific. The results of these two sensitive experiments testify to the fact that the meridional gradient in the chlorophyll-a concentration can result in an enhancement in the upper current and a decrease in the SST, along with the observation that a high chlorophyll-a concentration at the equator is one of the predominant reasons leading to a decrease in the SST. This study points out that these results can be qualitatively different simply because of the choice of the solar radiation penetration schemes for comparison. This can help explain previously reported contradictory conclusions.
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Chen, D., A. J. Busalacchi, and L. M. Rothstein, 1994: The roles of vertical mixing, solar radiation, and wind stress in a model simulation of the sea surface temperature seasonal cycle in the tropical Pacific Ocean. J. Geophys. Res., 99, 20345–20359.
Darnell, W. L., W. F. Staylor, N. A., Ritchey, S. K. Gupta, and A. C. Wilber, 1996: Surface Radiation Budget: A Long-term Global Dataset of Shortwave and Longwave Fluxes. EOS, Trans. Amer. Geophys. Union., Electron. Suppl., Feb. 27, 1996. [Available online from http://www.agu.org.eoselec/95206e.html].
Gent, P. R., and J. C. McWilliams, 1990: Isopycnal mixing in ocean circulation models. J. Phys. Oceanogr., 20, 150–155.
Gibson, J. K., P. Kållberg, S. Uppala, A. Hernandez, A. Nomura, and E. Serrano, 1997: ERA description. ECMWF Reanalysis Project Report Series No. 1, European Centre for Medium-Range Weather Forecasts, Reading, 72pp.
Gildor, H., A. H. Sobel, M. A. Cane, and R. N. Sambrotto, 2003: A role for ocean biota in tropical intraseasonal atmospheric variability. Geophys. Res. Lett., 30, 1460, doi: 10.1029/2002GL016759.
Griffies, S. M., R. C. Harrison, R. C. Pacanowski, and A. Rosati, 2003: A technical guide to MOM4. GFDL Ocean Group Tech. Rep., 5, 295pp.
Jerlov, N. G., 1968: Optical Oceanography. Elsevier Press, 194pp.
Latif, M., and Coauthors, 2001: ENSIP: The El Niño Simulation Intercomparison Project. Climate Dyn., 18, 255–276.
Liu, H., Y. Q. Yu, W. Li, and X. H. Zhang, 2004a: Manual for LASG/IAP Climate System Ocean Model (LICOM1.0). Science Press, Bei**g, 1–28. (in Chinese)
Liu, H., X. H. Zhang, W. Li, Y. Q. Yu, and R. C. Yu, 2004b: A eddy-permitting oceanic general circulation model and its preliminary evaluations. Adv. Atmos. Sci., 21, 675–690.
Manizza, M., C. Le Quéré, A. J. Watson, and E. T. Buitenhuis, 2005: Bio-optical feedbacks among phytoplankton, upper ocean physics and sea-ice in a global model. Geophys. Res. Lett., 32, L05603, doi: 10.1029/2004GL020778.
Marzeion, B., A. Timmermann, R. Murtugudde, and F. F. **, 2005: Bio-physical feedbacks in the tropical Pacific. J. Climate, 18, 58–70.
Mechoso, C. R., and Coauthors, 1995: The seasonal cycle over the tropical Pacific in coupled ocean-atmosphere general circulation models. Mon. Wea. Rev., 123, 2825–2838.
Morel, A., 1988: Optical modeling of the upper ocean in relation to its biogenous matter content (Case I waters). J. Geophys. Res., 93, 10749–10768.
Morel, A., and D. Antoine, 1994: Heating rate within the upper ocean in relation to its bio-optical state. J. Phys. Oceanogr., 24, 1652–1665.
Murtugudde, R., J. Beauchamp, C. R. McClain, M. Lewis, and A. J. Busalacchi, 2002: Effects of penetrative radiation on the upper tropical ocean circulation. J. Climate, 15, 470–486.
Nakamoto, S., S. P. Kumar, J. M. Oberhuber, J. Ishizaka, K. Muneyama, and R. Frouin, 2001: Response of the equatorial Pacific to chlorophyll pigment in a mixed layer isopycnal ocean general circulation model. Geophys. Res. Lett., 28, 2021–2024.
Ohlmann, J. C., 2003: Ocean radiant heating in climate models. J. Climate, 16, 1337–1351.
Pacanowski, R. C., and S. G. H. Philander, 1981: Parameterization of vertical mixing in numerical models of tropical oceans. J. Phys. Oceanogr., 11, 1443–1451.
Paulson, C. A., and J. J. Simpson, 1977: Irradiance measurements in the upper ocean. J. Phys. Oceanogr., 7, 952–956.
Rosati, A., and K. Miyakoda, 1988: A general circulation model for upper ocean circulation. J. Phys. Oceanogr., 18, 1601–1626.
Röske, F., 2001: An atlas of surface fluxes based on the ECMWF Re-Analysis—A climatological dataset to force global ocean general circulation models. Report No. 323, MPI, Hamburg, 31pp.
Schneider, E. K., and Z. X. Zhu, 1998: Sensitivity of the simulated annual cycle of sea surface temperature in the equatorial Pacific to sunlight penetration. J. Climate, 11, 1932–1950.
Shell, K. M., R. Frouin, S. Nakamoto, and R. C. J. Somerville, 2003: Atmospheric response to solar radiation absorbed by phytoplankton. J. Geophys. Res., 108, 4445, doi: 10.1029/2003JD003440.
Siegel, D. A., J. C. Ohlmann, L. Washburn, R. R. Bidigare, C. Nosse, E. Fields, and Y. Zhou, 1995: Solar radiation, phytoplankton pigments and radiant heating of the equatorial Pacific warm pool. J. Geophys. Res., 100, 4885–4891.
Strutton, P., and F. P. Chavez, 2004: Biological heating in the equatorial Pacific: Observed variability and potential for real-time calculation. J. Climate, 17, 1097–1109.
Sweeney, C., A. Gnanadesikan, S. M. Griffies, M. J. Harrison, A. J. Rosati, and B. L. Samuels, 2005: Impacts of shortwave penetration depth on large-scale ocean circulation and heat transport. J. Phys. Oceanogr., 35, 1103–1119.
Timmermann, A., and F. F. **, 2002: Phytoplankton influences on tropical climate. Geophys. Res. Lett., 29, 191–194.
Wetzel, P., E. Maier-Reimer, M. Botzet, J. Jungclaus, N. Keenlyside, and M. Latif, 2006: Effects of ocean biology on the penetrative radiation in a coupled climate model. J. Climate, 19, 3973–3987.
Wu, F. H., H. L. Liu, W. Li, and X. H. Zhang, 2005: Effect of adjusting vertical resolution on the eastern equatorial Pacific cold tongue. Acta Oceanologica Sinica, 24, 1–12.
Zhang, X. H., Y. Q. Yu, and H. L. Liu, 2003: The development and application of the oceanic circulation models, Part I: The global oceanic general circulation models. Chinese J. Atmos. Sci., 27, 607–617. (in Chinese)
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Lin, P., Liu, H. & Zhang, X. Sensitivity of the upper ocean temperature and circulation in the equatorial Pacific to solar radiation penetration due to phytoplankton. Adv. Atmos. Sci. 24, 765–780 (2007). https://doi.org/10.1007/s00376-007-0765-7
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DOI: https://doi.org/10.1007/s00376-007-0765-7