• Alexander, M., , and J. Scott, 2002: The influence of ENSO on air-sea interaction in the Atlantic. Geophys. Res. Lett., 29 , 1701. doi:10.1029/2001GL014347.

    • Search Google Scholar
    • Export Citation
  • Barreiro, M., , A. Giannini, , P. Chang, , and R. Saravanan, 2004: On the role of the Southern Hemisphere atmospheric circulation in tropical Atlantic variability. Earth’s Climate: The Ocean–Atmosphere Interaction, Geophys. Monogr. Ser., Vol. 147, Amer. Geophys. Union, 143–156.

    • Search Google Scholar
    • Export Citation
  • Barreiro, M., , P. Chang, , L. Ji, , R. Saravanan, , and A. Giannini, 2005: Dynamical elements of predicting boreal spring tropical Atlantic sea surface temperatures. Dyn. Atmos. Oceans, 39 , 6185.

    • Search Google Scholar
    • Export Citation
  • Benedict, J. J., , S. Lee, , and S. B. Feldstein, 2004: Synoptic view of the North Atlantic Oscillation. J. Atmos. Sci., 61 , 121144.

  • Biasutti, M., , A. H. Sobel, , and Y. Kushnir, 2006: AGCM precipitation biases in the tropical Atlantic. J. Climate, 19 , 935958.

  • Bretherton, C. S., , and A. H. Sobel, 2003: The Gill model and the weak temperature gradient approximation. J. Atmos. Sci., 60 , 451460.

    • Search Google Scholar
    • Export Citation
  • Chang, P., , L. Ji, , H. Li, , C. Penland, , and L. Matrosova, 1998: Prediction of tropical Atlantic sea surface temperature. Geophys. Res. Lett., 25 , 11931196.

    • Search Google Scholar
    • Export Citation
  • Chiang, J. C. H., , and A. H. Sobel, 2002: Tropical tropospheric temperature variations caused by ENSO and their influence on the remote tropical climate. J. Climate, 15 , 26162631.

    • Search Google Scholar
    • Export Citation
  • Czaja, A., , P. van der Vaart, , and J. Marshall, 2002: A diagnostic study of the role of remote forcing in tropical Atlantic variability. J. Climate, 15 , 32803290.

    • Search Google Scholar
    • Export Citation
  • Enfield, D. B., , and D. A. Mayer, 1997: Tropical Atlantic sea surface temperature variability and its relation to El Niño–Southern Oscillation. J. Geophys. Res., 102 , 929945.

    • Search Google Scholar
    • Export Citation
  • Enfield, D. B., , S-K. Lee, , and C. Wang, 2006: How are large Western Hemisphere warm pools formed? Prog. Oceanogr., 70 , 346365.

  • Feldstein, S. B., 2000: The timescale, power spectra, and climate noise properties of teleconnection patterns. J. Climate, 13 , 44304440.

    • Search Google Scholar
    • Export Citation
  • Giannini, A., , R. Saravanan, , and P. Chang, 2004: The preconditioning role of tropical Atlantic variability in the development of the ENSO teleconnection: Implications for the prediction of Nordeste rainfall. Climate Dyn., 22 , 839855.

    • Search Google Scholar
    • Export Citation
  • Gill, A. E., 1980: Some simple solutions for heat-induced tropical circulation. Quart. J. Roy. Meteor. Soc., 106 , 447462.

  • Horel, J. D., , and J. M. Wallace, 1981: Planetary-scale atmospheric phenomena associated with the Southern Oscillation. Mon. Wea. Rev., 109 , 813829.

    • Search Google Scholar
    • Export Citation
  • Huang, H-P., , A. W. Robertson, , and Y. Kushnir, 2005a: Atlantic SST gradient and the influence of ENSO. Geophys. Res. Lett., 32 , L20706. doi:10.1029/2005GL023944.

    • Search Google Scholar
    • Export Citation
  • Huang, H-P., , R. Seager, , and Y. Kushnir, 2005b: The 1976/77 transition in precipitation over the Americas and the influence of tropical sea surface temperature. Climate Dyn., 24 , 721740.

    • Search Google Scholar
    • Export Citation
  • Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77 , 437471.

  • Kushnir, Y., , W. A. Robinson, , P. Chang, , and A. W. Robertson, 2006: The physical basis for predicting Atlantic sector seasonal-to-interannual climate variability. J. Climate, 19 , 59495970.

    • Search Google Scholar
    • Export Citation
  • Lee, S-K., , D. B. Enfield, , and C. Wang, 2008: Why do some El Niños have no impact on tropical North Atlantic SST? Geophys. Res. Lett., 35 , L16705. doi:10.1029/2008GL034734.

    • Search Google Scholar
    • Export Citation
  • Liebmann, B., , and D. Allured, 2005: Daily precipitation grids for South America. Bull. Amer. Meteor. Soc., 86 , 15671570.

  • Misra, V., , and Y. Zhang, 2007: The fidelity of NCEP CFS seasonal hindcasts over Nordeste. Mon. Wea. Rev., 135 , 618627.

  • Nobre, C. A., , and L. C. B. Molion, 1988: The climatology of droughts and drought prediction. The Impact of Climate Variations on Agriculture: Assessments in Semi-Arid Regions, M. Parry, T. R. Carter, and N. T. Konjin, Eds., Kluwer Academic, 305–323.

    • Search Google Scholar
    • Export Citation
  • Peng, S., , W. A. Robinson, , S. Li, , and M. A. Alexander, 2006: Effects of Ekman transport on the NAO response to a tropical Atlantic SST anomaly. J. Climate, 19 , 48034818.

    • Search Google Scholar
    • Export Citation
  • Robinson, W. A., 2002: On the midlatitude thermal response to tropical warmth. Geophys. Res. Lett., 29 , 1190. doi:10.1029/2001GL014158.

  • Saravanan, R., , and P. Chang, 2004: Thermodynamic coupling and predictability of tropical sea surface temperature. Earth’s Climate: The Ocean–Atmosphere Interaction, Geophys. Monogr., Vol. 147, Amer. Geophys. Union, 171–180.

    • Search Google Scholar
    • Export Citation
  • Sardeshmukh, P. D., , G. P. Compo, , and C. Penland, 2000: Changes of probability associated with El Niño. J. Climate, 13 , 42684286.

  • Seager, R., , N. Harnik, , Y. Kushnir, , W. Robinson, , and J. Miller, 2003: Mechanisms of hemispherically symmetric climate variability. J. Climate, 16 , 29602978.

    • Search Google Scholar
    • Export Citation
  • Trenberth, K. E., , G. W. Branstator, , D. Karoly, , A. Kumar, , N-C. Lau, , and C. Ropelewski, 1998: Progress during TOGA in understanding and modeling global teleconnections associated with tropical sea surface temperature. J. Geophys. Res., 103 , 1429114324.

    • Search Google Scholar
    • Export Citation
  • Trzaska, S., , A. W. Robertson, , J. D. Farrara, , and C. R. Mechoso, 2007: South Atlantic variability arising from air–sea coupling: Local mechanisms and tropical–subtropical interactions. J. Climate, 20 , 33453365.

    • Search Google Scholar
    • Export Citation
  • Uvo, C. B., , C. A. Repelli, , S. E. Zebiak, , and Y. Kushnir, 1998: The relationship between tropical Pacific and Atlantic SST and northeast Brazil monthly precipitation. J. Climate, 11 , 551562.

    • Search Google Scholar
    • Export Citation
  • Wu, Z., , E. S. Sarachik, , and D. S. Battisti, 2001: Thermally driven tropical circulations under Rayleigh friction and Newtonian cooling. J. Atmos. Sci., 58 , 724741.

    • Search Google Scholar
    • Export Citation
  • Xie, S-P., 1999: A dynamic ocean–atmosphere model of the tropical Atlantic decadal variability. J. Climate, 12 , 6470.

  • Yulaeva, E., , and J. M. Wallace, 1994: The signature of ENSO in global temperature and precipitation fields derived from the microwave sounding unit. J. Climate, 7 , 17191736.

    • Search Google Scholar
    • Export Citation
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Hindcasts of Tropical Atlantic SST Gradient and South American Precipitation: The Influences of the ENSO Forcing and the Atlantic Preconditioning

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  • 1 Department of Mechanical and Aerospace Engineering, Arizona State University, Tempe, Arizona
  • | 2 International Research Institute for Climate and Society, Columbia University, New York, New York
  • | 3 Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York
  • | 4 NOAA/Earth System Research Laboratory/Physical Science Division, and CIRES Climate Diagnostics Center, University of Colorado, Boulder, Colorado
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Abstract

Hindcast experiments for the tropical Atlantic sea surface temperature (SST) gradient G1, defined as tropical North Atlantic SST anomaly minus tropical South Atlantic SST anomaly, are performed using an atmospheric general circulation model coupled to a mixed layer ocean over the Atlantic to quantify the contributions of the El Niño–Southern Oscillation (ENSO) forcing and the preconditioning in the Atlantic to G1 in boreal spring. The results confirm previous observational analyses that, in the years with a persistent ENSO SST anomaly from boreal winter to spring, the ENSO forcing plays a primary role in determining the tendency of G1 from winter to spring and the sign of G1 in late spring. In the hindcasts, the initial perturbations in Atlantic SST in boreal winter are found to generally persist beyond a season, leaving a secondary but nonnegligible contribution to the predicted Atlantic SST gradient in spring. For 1993/94, a neutral year with a large preexisting G1 in winter, the hindcast using the information of Atlantic preconditioning alone is found to reproduce the observed G1 in spring. The seasonal predictability in precipitation over South America is examined in the hindcast experiments. For the recent events that can be validated with high-quality observations, the hindcasts produced dryness in boreal spring 1983, wetness in spring 1996, and wetness in spring 1994 over northern Brazil that are qualitatively consistent with observations. An inclusion of the Atlantic preconditioning is found to help the prediction of South American rainfall in boreal spring. For the ENSO years, discrepancies remain between the hindcast and observed precipitation anomalies over northern and equatorial South America, an error that is partially attributed to the biased atmospheric response to ENSO forcing in the model. The hindcast of the 1993/94 neutral year does not suffer this error. It constitutes an intriguing example of useful seasonal forecast of G1 and South American rainfall anomalies without ENSO.

Corresponding author address: Huei-Ping Huang, Department of Mechanical and Aerospace Engineering, Arizona State University, Tempe, AZ 85287-6106. Email: hp.huang@asu.edu

Abstract

Hindcast experiments for the tropical Atlantic sea surface temperature (SST) gradient G1, defined as tropical North Atlantic SST anomaly minus tropical South Atlantic SST anomaly, are performed using an atmospheric general circulation model coupled to a mixed layer ocean over the Atlantic to quantify the contributions of the El Niño–Southern Oscillation (ENSO) forcing and the preconditioning in the Atlantic to G1 in boreal spring. The results confirm previous observational analyses that, in the years with a persistent ENSO SST anomaly from boreal winter to spring, the ENSO forcing plays a primary role in determining the tendency of G1 from winter to spring and the sign of G1 in late spring. In the hindcasts, the initial perturbations in Atlantic SST in boreal winter are found to generally persist beyond a season, leaving a secondary but nonnegligible contribution to the predicted Atlantic SST gradient in spring. For 1993/94, a neutral year with a large preexisting G1 in winter, the hindcast using the information of Atlantic preconditioning alone is found to reproduce the observed G1 in spring. The seasonal predictability in precipitation over South America is examined in the hindcast experiments. For the recent events that can be validated with high-quality observations, the hindcasts produced dryness in boreal spring 1983, wetness in spring 1996, and wetness in spring 1994 over northern Brazil that are qualitatively consistent with observations. An inclusion of the Atlantic preconditioning is found to help the prediction of South American rainfall in boreal spring. For the ENSO years, discrepancies remain between the hindcast and observed precipitation anomalies over northern and equatorial South America, an error that is partially attributed to the biased atmospheric response to ENSO forcing in the model. The hindcast of the 1993/94 neutral year does not suffer this error. It constitutes an intriguing example of useful seasonal forecast of G1 and South American rainfall anomalies without ENSO.

Corresponding author address: Huei-Ping Huang, Department of Mechanical and Aerospace Engineering, Arizona State University, Tempe, AZ 85287-6106. Email: hp.huang@asu.edu

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