Intraseasonal Surface Fluxes in the Tropical Western Pacific and Indian Oceans from NCEP Reanalyses

Toshiaki Shinoda Climate Diagnostics Center, University of Colorado, Boulder, Colorado

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Harry H. Hendon Climate Diagnostics Center, University of Colorado, Boulder, Colorado

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John Glick Climate Diagnostics Center, University of Colorado, Boulder, Colorado

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Abstract

Reliability of the surface fluxes from National Centers for Environmental Prediction (NCEP) reanalyses is assessed across the warm pool of the western Pacific and Indian Oceans. Emphasis is given to the spatial distribution and coherence of the fluxes on intraseasonal (25–100 day) periods, as intraseasonal variability predominates the subseasonal variability across the warm pool. Comparison is made with surface fluxes estimated from data collected at a mooring during the Coupled Ocean–Atmosphere Response Experiment and with independent gridded estimates based on operational wind and surface pressure analyses and satellite observations of rainfall, shortwave radiation, and outgoing longwave radiation. In general, fluxes that depend primarily on surface wind variations (e.g., stress and latent heat flux) agree more favorably than fluxes that are largely dependent on fluctuations of convection (e.g., surface shortwave radiation and freshwater or precipitation). In particular, the intraseasonal variance of shortwave radiation and precipitation in the NCEP reanalyses is about half of that estimated from in situ observations and from satellite observations. Composite surface flux variations for the Madden–Julian oscillation, which is the dominant mode of intraseasonal variability in the warm pool, are also constructed. Again, the composite variations of wind stress and latent heat flux from the NCEP reanalyses agree reasonably well, both in magnitude and phasing, with the composite fluxes from the independent gridded data. However, the composite intraseasonal shortwave radiation and precipitation from the NCEP reanalyses, while agreeing in phase, exhibit less than half the amplitude of the satellite-based estimates.

The impact of the underestimation of these surface flux variations in the NCEP reanalyses on the intraseasonal evolution of sea surface temperature (SST) in the warm pool is investigated in the context of a one-dimensional mixed layer model. When forced with the intraseasonal surface fluxes from the NCEP reanalyses, the amplitude of the intraseasonal SST variation is some 30%–40% smaller than observed or than that from forcing with the independent gridded fluxes. This reduced amplitude is primarily caused by the underestimation of the intraseasonal shortwave radiation variations in the NCEP reanalyses.

Corresponding author address: Dr. Toshiaki Shinoda, Climate Diagnostics Center, University of Colorado, Campus Box 449, Boulder, CO 80309.

Email: ts@cdc.noaa.gov

Abstract

Reliability of the surface fluxes from National Centers for Environmental Prediction (NCEP) reanalyses is assessed across the warm pool of the western Pacific and Indian Oceans. Emphasis is given to the spatial distribution and coherence of the fluxes on intraseasonal (25–100 day) periods, as intraseasonal variability predominates the subseasonal variability across the warm pool. Comparison is made with surface fluxes estimated from data collected at a mooring during the Coupled Ocean–Atmosphere Response Experiment and with independent gridded estimates based on operational wind and surface pressure analyses and satellite observations of rainfall, shortwave radiation, and outgoing longwave radiation. In general, fluxes that depend primarily on surface wind variations (e.g., stress and latent heat flux) agree more favorably than fluxes that are largely dependent on fluctuations of convection (e.g., surface shortwave radiation and freshwater or precipitation). In particular, the intraseasonal variance of shortwave radiation and precipitation in the NCEP reanalyses is about half of that estimated from in situ observations and from satellite observations. Composite surface flux variations for the Madden–Julian oscillation, which is the dominant mode of intraseasonal variability in the warm pool, are also constructed. Again, the composite variations of wind stress and latent heat flux from the NCEP reanalyses agree reasonably well, both in magnitude and phasing, with the composite fluxes from the independent gridded data. However, the composite intraseasonal shortwave radiation and precipitation from the NCEP reanalyses, while agreeing in phase, exhibit less than half the amplitude of the satellite-based estimates.

The impact of the underestimation of these surface flux variations in the NCEP reanalyses on the intraseasonal evolution of sea surface temperature (SST) in the warm pool is investigated in the context of a one-dimensional mixed layer model. When forced with the intraseasonal surface fluxes from the NCEP reanalyses, the amplitude of the intraseasonal SST variation is some 30%–40% smaller than observed or than that from forcing with the independent gridded fluxes. This reduced amplitude is primarily caused by the underestimation of the intraseasonal shortwave radiation variations in the NCEP reanalyses.

Corresponding author address: Dr. Toshiaki Shinoda, Climate Diagnostics Center, University of Colorado, Campus Box 449, Boulder, CO 80309.

Email: ts@cdc.noaa.gov

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  • Bony, S., Y. Sud, K. M. Lau, J. Susskind, and S. Saha, 1997: Comparison and satellite assessment of NASA/DAO and NCEP–NCAR reanalyses over tropical ocean: Atmospheric hydrology and radiation. J. Climate,10, 1441–1462.

  • Berliand, M. E., and T. G. Berliand, 1952: Determining the net longwave radiation of the earth with consideration of the effect of cloudiness (in Russian). Izv. Akad. Nauk SSSR, Ser. Geofiz.,1.

  • Fairall, C., E. F. Bradley, D. P. Rogers, J. B. Edson, and G. S. Young, 1996: The TOGA COARE bulk flux algorithm. J. Geophys. Res.,101, 3747–3764.

  • Feng, M., P. Hacker, and R. Lukas, 1997: Upper ocean heat and salt balances in response to a westerly wind burst in the western equatorial Pacific. J. Geophys. Res.,103, 10 289–10 311.

  • Gruber, A., and A. F. Krueger, 1984: The status of the NOAA outgoing longwave radiation data set. Bull. Amer. Meteor. Soc.,65, 958–962.

  • Gutzler, D. S., G. N. Kiladis, G. A. Meehl, K. M. Weickmann, and M. Wheeler, 1994: The global climate of December 1992–February 1993. Part II: Large-scale variability across the tropical western Pacific during TOGA COARE. J. Climate,7, 1606–1622.

  • Hendon, H. H., and J. Glick, 1997: Intraseasonal air–sea interaction in the tropical Indian and Pacific Oceans. J. Climate,10, 647–661.

  • Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc.,77, 437–471.

  • Kessler, W. S., M. J. McPhaden, and K. M. Weickmann, 1995: Forcing of intraseasonal Kelvin waves in the equatorial Pacific Ocean. J. Geophys. Res.,100, 10 613–10 631.

  • Lau, K.-M., and C.-H. Sui, 1997: Mechanisms of short-term sea surface temperature regulation: Observations from TOGA COARE. J. Climate,10, 465–472.

  • Levitus, S., and T. P. Boyer, 1994: World Ocean Atlas. Vol. 4, Temperature, NOAA, 117 pp.

  • ——, R. Burgett, and T. P. Boyer, 1994: World Ocean Atlas. Vol. 3, Salinity, NOAA, 97 pp.

  • Li, Z., and H. G. Leighton, 1993: Global climatologies of solar radiation budgets at the surface and in the atmosphere from 5 years of ERBE data. J. Geophys. Res.,98, 4919–4930.

  • Liebmann, B., and C. A. Smith, 1996: Description of a complete (interpolated) outgoing longwave radiation dataset. Bull. Amer. Meteor. Soc.,77, 1275–1277.

  • Madden, R. A., and P. R. Julian, 1971: Detection of a 40–50 day oscillation in the zonal wind in the tropical Pacific. J. Atmos. Sci.,28, 702–208.

  • ——, and ——, 1972: Description of global-scale circulation cells in the Tropics with a 40–50 day period. J. Atmos. Sci.,29, 1109–1123.

  • Paulson, C. A., and J. J. Simpson, 1977: Irradience measurements in the upper ocean. J. Phys. Oceanogr.,7, 952–956.

  • Pinker, R., and I. Laszlo, 1992: Modeling of surface solar irradiance for satellite applications on a global scale. J. Appl. Meteor.,31, 194–211.

  • Price, J. F., R. A. Weller, and R. Pinkel, 1986: Diurnal cycling: Observations and models of the upper ocean response to diurnal heating, cooling, and wind mixing. J. Geophys. Res.,91 (C7), 8411–8427.

  • Ralph, E. A., K. Bi, and P. P. Niiler, 1997: A Lagrangian description of the western equatorial Pacific response to the wind burst of December 1992. J. Climate,10, 1706–1721.

  • Reynolds, R. W., and T. M. Smith, 1994: Improved global sea surface temperature analyses using optimum interpolation. J. Climate,7, 929–948.

  • Rossow, W. B., and R. A. Schiffer, 1991: ISCCP cloud data products. Bull. Amer. Meteor. Soc.,72, 2–20.

  • Salby, M. L., and H. H. Hendon, 1994: Intraseasonal behavior of clouds, temperature, and motion in the Tropics. J. Atmos. Sci.,51, 2207–2224.

  • Shinoda, T., and H. H. Hendon, 1998: Mixed layer modeling of intraseasonal variability in the tropical western Pacific and Indian Oceans. J. Climate,11, 2668–2685.

  • ——, ——, and J. Glick, 1998: Intraseasonal variability of surface fluxes and sea surface temperature in the tropical western Pacific and Indian Oceans. J. Climate,11, 1685–1702.

  • Spencer, R. W., 1993: Global oceanic precipitation from the MSU during 1979–91 and comparisons to other climatologies. J. Climate,6, 1301–1326.

  • Waliser, D. E., and N. E. Graham, 1993: Convective cloud systems and warm-pool sea surface temperatures: Coupled interactions and self-regulation. J. Geophys. Res.,98 (D7), 12 881–12 893.

  • Weare, B. C., 1997: Comparison of NCEP–NCAR cloud radiative forcing reanalyses with observations. J. Climate,10, 2200–2209.

  • Webster, P. J., and R. Lukas, 1992: The Tropical Ocean Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (COARE). Bull. Amer. Meteor. Soc.,73, 1377–1416.

  • Weller, R. A., and S. P. Anderson, 1996: Surface meteorology and air–sea fluxes in the western equatorial Pacific warm pool during the TOGA Coupled Ocean Atmosphere Response Experiment. J. Climate,9, 1959–1990.

  • Whitlock, C. H., and Coauthors, 1995: First Global WCRP shortwave surface radiation budget dataset. Bull. Amer. Meteor. Soc.,76, 905–922.

  • Zeng, X., M. Zhao, and R. E. Dickinson, 1998: Intercomparison of bulk aerodynamic algorithms for the computation of sea surface fluxes using the TOGA COARE and TAO data. J. Climate,11, 2628–2644.

  • Zhang, C., 1996: Atmospheric intraseasonal variability at the surface in the tropical western Pacific Ocean. J. Atmos. Sci.,53, 739–758.

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