The Effect of Milankovitch Variations in Insolation on Equatorial Seasonality

Yosef Ashkenazy Department of Solar Energy and Environmental Physics, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel

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Ian Eisenman Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, and Department of Atmospheric Sciences, University of Washington, Seattle, Washington

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Hezi Gildor The Fredy and Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel

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Eli Tziperman Department of Earth and Planetary Sciences, and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts

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Abstract

Although the sun crosses the equator 2 times per year at the equinoxes, at times in the past the equatorial insolation has had only one maximum and one minimum throughout the seasonal cycle because of Milankovitch orbital variations. Here a state-of-the-art coupled atmosphere–ocean general circulation model is used to study the effect of such insolation forcing on equatorial surface properties, including air and sea temperature, salinity, winds, and currents. It is shown that the equatorial seasonality is altered according to the insolation with, for example, either maximum sea surface temperature (SST) close to the vernal equinox and minimum SST close to the autumnal equinox or vice versa. The results may have important implications for understanding tropical climate as well as for the interpretation of proxy data collected from equatorial regions.

Corresponding author address: Yosef Ashkenazy, Department of Solar Energy and Environmental Physics, BIDR, Ben-Gurion University of the Negev, 84990 Midreshet Ben-Gurion, Israel. Email: ashkena@bgu.ac.il

Abstract

Although the sun crosses the equator 2 times per year at the equinoxes, at times in the past the equatorial insolation has had only one maximum and one minimum throughout the seasonal cycle because of Milankovitch orbital variations. Here a state-of-the-art coupled atmosphere–ocean general circulation model is used to study the effect of such insolation forcing on equatorial surface properties, including air and sea temperature, salinity, winds, and currents. It is shown that the equatorial seasonality is altered according to the insolation with, for example, either maximum sea surface temperature (SST) close to the vernal equinox and minimum SST close to the autumnal equinox or vice versa. The results may have important implications for understanding tropical climate as well as for the interpretation of proxy data collected from equatorial regions.

Corresponding author address: Yosef Ashkenazy, Department of Solar Energy and Environmental Physics, BIDR, Ben-Gurion University of the Negev, 84990 Midreshet Ben-Gurion, Israel. Email: ashkena@bgu.ac.il

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  • Ashkenazy, Y., and E. Tziperman, 2006: Scenarios regarding the lead of equatorial sea surface temperature over global ice volume. Paleoceanography, 21 , PA2006. doi:10.1029/2005PA001232.

    • Search Google Scholar
    • Export Citation
  • Ashkenazy, Y., and H. Gildor, 2008: Timing and significance of maximum and minimum equatorial insolation. Paleoceanography, 23 , PA1206. doi:10.1029/2007PA001436.

    • Search Google Scholar
    • Export Citation
  • Berger, A., 1978: Long-term variations of daily insolation and quaternary climate changes. J. Atmos. Sci., 35 , 23622367.

  • Berger, A., M. F. Loutre, and J. L. Mélice, 2006: Equatorial insolation: From precession harmonics to eccentricity frequencies. Climate Past, 2 , 131136.

    • Search Google Scholar
    • Export Citation
  • Cane, M. A., 1998: Climate change: A role for the tropical Pacific. Science, 282 , 5961.

  • Chang, P., 1996: The role of the dynamic ocean–atmosphere interactions in the tropical seasonal cycle. J. Climate, 9 , 29732985.

  • Clement, A. C., R. Seager, and M. A. Cane, 1999: Orbital controls on the El Niño/Southern Oscillation and the tropical climate. Paleoceanography, 14 , 441456.

    • Search Google Scholar
    • Export Citation
  • Collins, W. D., and Coauthors, 2006: The Community Climate System Model version 3 (CCSM3). J. Climate, 19 , 21222143.

  • Crowley, T. J., K-Y. Kim, J. G. Mengel, and D. A. Short, 1992: Modeling 100,000-year climate fluctuations in pre-Pleistocene time series. Science, 255 , 705707.

    • Search Google Scholar
    • Export Citation
  • Dima, I. M., and J. M. Wallace, 2003: On the seasonality of the Hadley cell. J. Atmos. Sci., 60 , 15221527.

  • Galanti, E., and E. Tziperman, 2000: ENSO’s phase locking to the seasonal cycle in the fast SST, fast wave, and mixed mode regimes. J. Atmos. Sci., 57 , 29362950.

    • Search Google Scholar
    • Export Citation
  • Galanti, E., E. Tziperman, M. Harrison, A. Rosati, R. Giering, and Z. Sirkes, 2002: The equatorial thermocline outcropping—A seasonal control on the tropical Pacific ocean–atmosphere instability strength. J. Climate, 15 , 27212739.

    • Search Google Scholar
    • Export Citation
  • Gildor, H., and M. Ghil, 2002: Phase relations between climate proxy records: Potential effect of seasonal precipitation changes. Geophys. Res. Lett., 29 , 1024. doi:10.1029/2001GL013781.

    • Search Google Scholar
    • Export Citation
  • Gu, D., S. G. H. Philander, and M. J. McPhaden, 1997: The seasonal cycle and its modulation in the eastern tropical Pacific Ocean. J. Phys. Oceanogr., 27 , 22092218.

    • Search Google Scholar
    • Export Citation
  • Held, I. M., and A. Y. Hou, 1980: Nonlinear axially symmetric circulations in a nearly inviscid atmosphere. J. Atmos. Sci., 37 , 515533.

    • Search Google Scholar
    • Export Citation
  • Horel, J. D., 1982: On the annual cycle of the tropical Pacific atmosphere and ocean. Mon. Wea. Rev., 110 , 18631878.

  • Hou, A. Y., and R. S. Lindzen, 1992: The influence of concentrated heating on the Hadley circulation. J. Atmos. Sci., 49 , 12331241.

  • Huybers, P., and P. Molnar, 2007: Tropical cooling and the onset of North American glaciation. Climate Past, 3 , 549557.

  • Köberle, C., and S. G. H. Philander, 1994: On the processes that control seasonal variations of sea surface temperatures in the tropical Pacific ocean. Tellus, 46A , 481496.

    • Search Google Scholar
    • Export Citation
  • Kukla, G., and J. Gavin, 2004: Milankovitch climate reinforcements. Global Planet. Change, 40 , 2748.

  • Kukla, G., and J. Gavin, 2005: Did glacials start with global warming? Quat. Sci. Rev., 24 , 15471557.

  • Laskar, J., 1990: The chaotic motion of the solar system: A numerical estimate of the chaotic zones. Icarus, 88 , 266291.

  • Laskar, J., F. Joutel, and F. Boudin, 1993: Orbital, precessional, and insolation quantities for the earth from −20 myr to +10 myr. Astron. Astrophys., 270 , 522533.

    • Search Google Scholar
    • Export Citation
  • Li, T., and S. G. H. Philander, 1996: On the annual cycle of the eastern equatorial Pacific. J. Climate, 9 , 29862998.

  • Li, T., and S. G. H. Philander, 1997: On the seasonal cycle of the equatorial Atlantic Ocean. J. Climate, 10 , 813817.

  • Lindzen, R. S., and A. Y. Hou, 1988: Hadley circulations for zonally averaged heating centered off the equator. J. Atmos. Sci., 45 , 24162427.

    • Search Google Scholar
    • Export Citation
  • Meehl, G. A., and Coauthors, 2006: Climate change projections for the twenty-first century and climate change commitment in the CCSM3. J. Climate, 19 , 25972616.

    • Search Google Scholar
    • Export Citation
  • Milankovitch, M., 1941: Canon of Insolation and the Ice-Age Problem (in German). Special Publications of the Royal Serbian Academy, Vol. 132, Israel Program for Scientific Translations, 484 pp.

    • Search Google Scholar
    • Export Citation
  • Mitchell, T. P., and J. M. Wallace, 1992: The annual cycle in equatorial convection and sea surface temperature. J. Climate, 5 , 11401156.

    • Search Google Scholar
    • Export Citation
  • Nigam, S., and Y. Chao, 1996: Evolution dynamics of tropical ocean–atmosphere annual cycle variability. J. Climate, 9 , 31873205.

  • Otto-Bliesner, B. L., and A. Clement, 2005: The sensitivity of the Hadley circulation to past and future forcings in two climate models. The Hadley Circulation: Present, Past, and Future, H. F. Diaz and S. Raymond, Eds., Advances in Global Change Research, Vol. 21, Springer, 437–464.

    • Search Google Scholar
    • Export Citation
  • Otto-Bliesner, B. L., E. C. Brady, G. Clauzet, R. Tomas, S. Levis, and Z. Kothavala, 2006: Last Glacial Maximum and Holocene climate in CCSM3. J. Climate, 19 , 25262544.

    • Search Google Scholar
    • Export Citation
  • Paillard, D., 2001: Glacial cycles: Toward a new paradigm. Rev. Geophys., 39 , 325346.

  • Philander, S. G. H., W. J. Hurlin, and A. D. Siegel, 1987: Simulation of the seasonal cycle of the tropical Pacific Ocean. J. Phys. Oceanogr., 17 , 19862002.

    • Search Google Scholar
    • Export Citation
  • Philander, S. G. H., D. Gu, D. Halpern, G. Lambert, N-C. Lau, T. Li, and R. C. Pacanowski, 1996: Why the ITCZ is mostly north of the equator. J. Climate, 9 , 29582972.

    • Search Google Scholar
    • Export Citation
  • Sachs, J. P., R. H. Sachse, D. Smittenberg, Z. Zhang, D. S. Battisti, and S. Golubic, 2009: Southward movement of the Pacific intertropical convergence zone AD 1400–1850. Nat. Geosci., 2 , 519525.

    • Search Google Scholar
    • Export Citation
  • Schneider, T., 2006: The general circulation of the atmosphere. Annu. Rev. Earth Planet. Sci., 34 , 655688. doi:10.1146/annurev.earth.34.031405.125144.

    • Search Google Scholar
    • Export Citation
  • Short, D. A., J. G. Mengel, T. J. Crowley, W. T. Hyde, and G. R. North, 1991: Filtering of Milankovitch cycles by Earth’s geography. Quat. Res., 35 , 157173.

    • Search Google Scholar
    • Export Citation
  • Tziperman, E., L. Stone, M. A. Cane, and H. Jarosh, 1994: El Niño chaos: Overlapping of resonances between the seasonal cycle and the Pacific ocean-atmosphere oscillator. Science, 264 , 7274.

    • Search Google Scholar
    • Export Citation
  • Tziperman, E., S. E. Zebiak, and M. A. Cane, 1997: Mechanisms of seasonal – ENSO interaction. J. Atmos. Sci., 54 , 6171.

  • Tziperman, E., M. A. Cane, S. E. Zebiak, Y. Xue, and B. Blumenthal, 1998: Locking of El Niño’s peak time to the end of the calendar year in the delayed oscillator picture of ENSO. J. Climate, 11 , 21912199.

    • Search Google Scholar
    • Export Citation
  • Walker, C. C., and T. Schneider, 2006: Eddy influences on Hadley circulations: Simulations with an idealized GCM. J. Atmos. Sci., 63 , 33333350.

    • Search Google Scholar
    • Export Citation
  • Wang, B., and Y. Wang, 1999: Dynamics of the ITCZ–equatorial cold tongue complex and causes of the latitudinal climate asymmetry. J. Climate, 12 , 18301847.

    • Search Google Scholar
    • Export Citation
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