Generalized Inversion of Tropical Atmosphere–Ocean Data and a Coupled Model of the Tropical Pacific

Andrew F. Bennett College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon

Search for other papers by Andrew F. Bennett in
Current site
Google Scholar
PubMed
Close
,
Boon S. Chua College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon

Search for other papers by Boon S. Chua in
Current site
Google Scholar
PubMed
Close
,
D. Ed Harrison Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, Washington

Search for other papers by D. Ed Harrison in
Current site
Google Scholar
PubMed
Close
, and
Michael J. McPhaden Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, Washington

Search for other papers by Michael J. McPhaden in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

It is hypothesized that the circulation of the tropical Pacific Ocean and atmosphere satisfies the equations of a simple coupled model to within errors having specified covariances, and that the Tropical Atmosphere–Ocean array (TAO) measures the circulation to within errors also having specified covariances. This hypothesis is tested by finding the circulation that is the weighted least squares best fit to the dynamics of the simple model, to its initial and boundary conditions, and to a year of monthly mean TAO data for sea surface temperature, for the depth of the 20°C isotherm, and for surface winds. The fit is defined over the entire tropical Pacific and from 1 April 1994 to 31 March 1995. The best-fit circulation or state estimate is calculated using variational methods. Posterior error covariances are estimated using statistical simulation. The best fit is also subjected to a significance test.

It is found that, although the fit to data is largely within standard errors, the misfit to dynamics is significantly larger than standard errors. These standard errors are estimated a priori, and with difficulty, from published scale analyses of tropical circulation. An examination of the dynamical residuals indicates that the simple coupled model should be improved by including momentum advection both in the oceanic and atmospheric components.

Corresponding author address: Dr. Andrew F. Bennett, Oregon State University, College of Oceanic and Atmospheric Sciences, Oceanography Adm. Bldg. 104, Corvallis, OR 97331-5503.

Abstract

It is hypothesized that the circulation of the tropical Pacific Ocean and atmosphere satisfies the equations of a simple coupled model to within errors having specified covariances, and that the Tropical Atmosphere–Ocean array (TAO) measures the circulation to within errors also having specified covariances. This hypothesis is tested by finding the circulation that is the weighted least squares best fit to the dynamics of the simple model, to its initial and boundary conditions, and to a year of monthly mean TAO data for sea surface temperature, for the depth of the 20°C isotherm, and for surface winds. The fit is defined over the entire tropical Pacific and from 1 April 1994 to 31 March 1995. The best-fit circulation or state estimate is calculated using variational methods. Posterior error covariances are estimated using statistical simulation. The best fit is also subjected to a significance test.

It is found that, although the fit to data is largely within standard errors, the misfit to dynamics is significantly larger than standard errors. These standard errors are estimated a priori, and with difficulty, from published scale analyses of tropical circulation. An examination of the dynamical residuals indicates that the simple coupled model should be improved by including momentum advection both in the oceanic and atmospheric components.

Corresponding author address: Dr. Andrew F. Bennett, Oregon State University, College of Oceanic and Atmospheric Sciences, Oceanography Adm. Bldg. 104, Corvallis, OR 97331-5503.

Save
  • Battisti, D. S., 1988: Dynamics and thermodynamics of a warming event in a coupled tropical atmosphere–ocean model. J. Atmos. Sci.,45, 2889–2919.

  • Bennett, A. F., 1990: Inverse methods for assessing ship-of-opportunity networks and estimating circulation and winds from tropical expendable bathythermograph data. J. Geophys. Res.,95, 16 111–16 148.

  • ——, 1992: Inverse Methods in Physical Oceanography. Monogr. on Mech. Appl. Math., Cambridge University Press, 346 pp.

  • ——, B. S. Chua, and L. M. Leslie, 1996: Generalized inversion of a global numerical weather prediction model. Meteor. Atmos. Phys.,60, 165–178.

  • ——, ——, and ——, 1997: Generalized inversion of a global numerical weather prediction model. Part II: Analysis and implementation. Meteor. Atmos. Phys.,62, 129–140.

  • Bretherton, C. S., C. Smith, and J. M. Wallace, 1992: An intercomparison of methods for finding coupled patterns in climate date. J. Climate,5, 341–560.

  • Chan, N. H., J. B. Kadane, R. N. Miller, and W. Palma, 1996: Estimation of tropical sea level anomaly by an improved Kalman filter. J. Phys. Oceanogr.,16, 1286–1303.

  • Chen, D., S. E. Zebiak, A. J. Busalacchi, and M. A. Cane, 1995: An improved procedure for El Niño forecasting: Implications for predictability. Science,269, 1699–1701.

  • Courant, R., and D. Hilbert, 1953: Methods of Mathematical Physics. Vol. 1. Interscience, 560 pp.

  • Egbert, G. D., and A. F. Bennett, 1996: Data assimilation methods for ocean tides. Modern Approaches to Data Assimilation in Ocean Modeling, P. Malanotti-Rizzoli, Ed., Elsevier, 455 pp.

  • ——, ——, and M. G. G. Foreman, 1994: TOPEX/Poseidon tides estimated using a global inverse model. J. Geophys. Res.,99, 24 821–24 852.

  • Esbensen, S. K., and M. J. McPhaden, 1996: Enhancement of tropical ocean evaporation and sensible heat flux by atmospheric mesoscale systems. J. Climate,9, 2307–2325.

  • Gill, A. E., 1980: Some simple solutions for heat-induced tropical circulation. Quart. J. Roy. Meteor. Soc.,106, 447–462.

  • Harrison, D. E., 1987: Monthly mean island surface winds in the central tropical Pacific and El Niño events. Mon. Wea. Rev.,115, 3133–3145.

  • ——, and D. S. Luther, 1990: Surface winds from tropical Pacific islands—Climatological statistics. J. Climate,3, 251–271.

  • Hayes, S. P., M. J. McPhaden, and J. M. Wallace, 1989: The influence of sea surface temperature on surface wind in the eastern equatorial Pacific: Weekly to monthly variability. J. Climate,2, 1500–1506.

  • Ji, M., and A. Leetma, 1997: Impact of data assimilation on ocean initialization and El Niño prediction. Mon. Wea. Rev.,125, 742–753.

  • Kessler, W. S., 1990: Observations of long Rossby waves in the northern tropical Pacific. J. Geophys. Res.,95, 5183–5217.

  • ——, and J. P. McCreary Jr., 1993: The annual wind-driven Rossby wave in the subthermocline equatorial Pacific. J. Phys. Oceanogr.,23, 1192–1207.

  • ——, and M. J. McPhaden, 1995a: The 1991–93 El Niño in the central Pacific. Deep-Sea Res.,42, 295–334.

  • ——, and ——, 1995b: Oceanic equatorial waves and the 1991–93 El Niño. J. Climate,8, 1757–1774.

  • ——, M. C. Spillane, M. J. McPhaden, and D. E. Harrison, 1996: Scales of variability in the equatorial Pacific inferred from the Tropical Atmosphere–Ocean buoy array. J. Climate,9, 2999–3024.

  • Kleeman, R., A. M. Moore, and N. R. Smith, 1995: Assimilation of subsurface thermal data into a simple ocean model for the initialization of an intermediate tropical coupled ocean–atmosphere forecast model. Mon. Wea. Rev.,123, 3103–3113.

  • Mantua, N. J., and D. S. Battisti, 1995: Aperiodic variability in the Zebiak–Cane coupled ocean–atmosphere model: Air–sea interactions in the western equatorial Pacific. J. Climate,8, 2897–2927.

  • McCreary, J. P., and Z. Yu, 1992: Equatorial dynamics in a two and one-half-layer model. Progress in Oceanography, Vol. 29, Pergamon Press, 61–132.

  • McPhaden, M. J., 1993: TOGA-TAO and the 1991–93 El Niño Southern Oscillation event. Oceanography6, 36–44.

  • ——, 1995: The Tropical Atmosphere-Ocean array is completed. Bull. Amer. Meteor. Soc.,76, 739–742.

  • ——, and M. E. McCarty, 1992: Mean seasonal cycles and interannual variations at 0°, 110°W and 0°, 140°W during 1980–91. NOAA Tech. Memo. ERL PMEL-95, U.S. Dept. of Commerce, Washington, DC, 118 pp.

  • Miller, R. N., A. J. Busalacchi, and E. C. Hackert, 1995: Sea surface topography fields of the tropical Pacific from data assimilation. J. Geophys. Res.,100, 13 389–13 425.

  • NOAA, 1994/95: Climate Diagnostics Bulletins #94/1-95/6. NOAA/NWS/National Centers for Environmental Prediction. [Available from NOAA Science Center, Rm. 605, 5200 Auth Rd., Washington, DC 20233.].

  • Rasmussen, E. M., and T. H. Carpenter, 1982: Variations in tropical sea surface temperature and surface wind fields associated with the Southern Oscillation/El Niño. Mon. Wea. Rev.,110, 354–384.

  • Reynolds, R. W., and T. M. Smith, 1995: A high-resolution global sea surface temperature climatology. J. Climate,8, 1571–1583.

  • Soreide, N. N., D. C. McClurg, W. H. Zhu, M. J. McPhaden, D. W. Denbo, and M. W. Renton, 1996: World Wide Web access to real-time and historical data from the TAO array of moored buoys in the tropical Pacific Ocean: Updates for 1996. Proc. OCEANS 96, Fort Lauderdale, FL, MTS/IEEE, 1354–1359.

  • Talagrand, O., 1972: On the damping of high-frequency motions in four-dimensional assimilation of meteorological data. J. Atmos. Sci.,29, 1571–1574.

  • Wallace, J. M., T. P. Mitchell, and C. Deser, 1989: The influence of sea-surface temperature on surface wind in the eastern equatorial Pacific: Seasonal and interannual variability. J. Climate,2, 1492–1499.

  • ——, C. Smith, and C. S. Bretherton, 1992: Singular value decomposition of wintertime sea surface temperature and 500-mb height anomalies. J. Climate,5, 561–576.

  • Woodruff, S. D., R. J. Slutz, R. L. Jenne, and P. Steurer, 1987: A comprehensive ocean–atmosphere data set. Bull. Amer. Meteor. Soc.,68, 1239–1250.

  • Yu, L., and J. J. O’Brien, 1995: Variational assimilation for determining the seasonal net surface heat flux using a tropical Pacific Ocean model. J. Phys. Oceanogr.,25, 2319–2343.

  • Zebiak, S. E., and M. A. Cane, 1987: A model El Niño/Southern Oscillation. Mon. Wea. Rev.,115, 2262–2278.

  • Zhang, G. J., and M. J. McPhaden, 1995: On the relationship between sea surface temperature and latent heat flux in the equatorial Pacific. J. Climate,8, 589–605.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 567 315 7
PDF Downloads 72 23 0