Editorial Type:
Article
Article Type:
Research Article

The Impact of Clouds on the Seasonal Cycle of Radiative Heating over the Pacific

John W. Bergman NOAA–CIRES Climate Diagnostics Center, Boulder, Colorado

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Harry H. Hendon NOAA–CIRES Climate Diagnostics Center, Boulder, Colorado

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Print Publication:
01 Feb 2000
DOI:
https://doi.org/10.1175/1520-0469(2000)057<0545:TIOCOT>2.0.CO;2
Page(s):
545–566
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Abstract

Seasonal variations of cloud radiative forcing (CRF) are calculated from observed cloud properties in the International Satellite Cloud Climatology Project over the Pacific between 30°S and 30°N. Using 7 yr of data, the first annual harmonic of CRF is statistically significant with respect to the background red noise spectrum at better than a 0.99 confidence level at most locations. It is significant with respect to calculation error at better than a 0.90 confidence level at those same locations. Calculated annual variations are strongest in the subtropics and equatorial east Pacific.

In a linear analysis, annual variations of CRF are attributed to individual annual variations of cloud properties, insolation, or surface temperature. At higher latitudes, the seasonal cycle of CRF at the top of the atmosphere (TOA) and at the surface is dominated by the shortwave (SW) component and results primarily from the seasonal cycle of insolation interacting with the time mean cloud field. Annual variations of cloud fraction and of cloud optical depth are both important in the Tropics, particularly in the east Pacific. Longwave (LW) CRF at TOA is strongest at locations where the seasonal cycle of convection is strong. At those locations, annual variations of CRF result primarily from annual variations of cloud height and not from annual variations of cloud fraction. At the surface, annual variations of LW CRF are small throughout. The annual variations of atmospheric CRF are dominated by the LW component, with the SW component contributing about 20%. As with LW CRF at TOA, annual variations of atmospheric CRF are strongest over convective locations and result from annual variations of cloud height.

The impact of cloud radiative forcing on zonal circulations in the equatorial Pacific and on SST in the east Pacific was analyzed. CRF represents approximately 20% of the annual variations of diabatic heating rates over convective locations and 50% or better at nonconvective locations. Annual variations of atmospheric CRF, when strong, tend to be in phase with those of total diabatic heating rates, indicating that clouds reinforce tropical circulations driven by latent heating.

The role of clouds is particularly important in the east Pacific between 85° and 105°W. Atmospheric CRF is a major component of total diabatic heating over the cold tongue, where seasonal variations of SST are strongest. If seasonal variations of SST in the cold tongue result from seasonal variations of upwelling driven by meridional wind variability, then CRF may play an important role. In contrast, CRF at the surface has only a weak seasonal cycle, with a phase that is not consistent as a forcing for seasonal variations of SST.

Corresponding author address: John Bergman, NOAA–CIRES Climate Diagnostics Center, Mail Code R/E/CD1, 325 Broadway, Boulder, CO 80303-3328.

Abstract

Seasonal variations of cloud radiative forcing (CRF) are calculated from observed cloud properties in the International Satellite Cloud Climatology Project over the Pacific between 30°S and 30°N. Using 7 yr of data, the first annual harmonic of CRF is statistically significant with respect to the background red noise spectrum at better than a 0.99 confidence level at most locations. It is significant with respect to calculation error at better than a 0.90 confidence level at those same locations. Calculated annual variations are strongest in the subtropics and equatorial east Pacific.

In a linear analysis, annual variations of CRF are attributed to individual annual variations of cloud properties, insolation, or surface temperature. At higher latitudes, the seasonal cycle of CRF at the top of the atmosphere (TOA) and at the surface is dominated by the shortwave (SW) component and results primarily from the seasonal cycle of insolation interacting with the time mean cloud field. Annual variations of cloud fraction and of cloud optical depth are both important in the Tropics, particularly in the east Pacific. Longwave (LW) CRF at TOA is strongest at locations where the seasonal cycle of convection is strong. At those locations, annual variations of CRF result primarily from annual variations of cloud height and not from annual variations of cloud fraction. At the surface, annual variations of LW CRF are small throughout. The annual variations of atmospheric CRF are dominated by the LW component, with the SW component contributing about 20%. As with LW CRF at TOA, annual variations of atmospheric CRF are strongest over convective locations and result from annual variations of cloud height.

The impact of cloud radiative forcing on zonal circulations in the equatorial Pacific and on SST in the east Pacific was analyzed. CRF represents approximately 20% of the annual variations of diabatic heating rates over convective locations and 50% or better at nonconvective locations. Annual variations of atmospheric CRF, when strong, tend to be in phase with those of total diabatic heating rates, indicating that clouds reinforce tropical circulations driven by latent heating.

The role of clouds is particularly important in the east Pacific between 85° and 105°W. Atmospheric CRF is a major component of total diabatic heating over the cold tongue, where seasonal variations of SST are strongest. If seasonal variations of SST in the cold tongue result from seasonal variations of upwelling driven by meridional wind variability, then CRF may play an important role. In contrast, CRF at the surface has only a weak seasonal cycle, with a phase that is not consistent as a forcing for seasonal variations of SST.

Corresponding author address: John Bergman, NOAA–CIRES Climate Diagnostics Center, Mail Code R/E/CD1, 325 Broadway, Boulder, CO 80303-3328.

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  • Barkstrom, B. R., 1984: The Earth Radiation Budget Experiment (ERBE). Bull. Amer. Meteor. Soc.,65, 1170–1185.

  • Bergman, J. W., and H. H. Hendon, 1998: Calculating monthly radiative fluxes and heating rates from monthly observations of cloud cover. J. Atmos. Sci.,55, 3471–3491.

  • Bess, T. D., G. L. Smith, T. P. Charlock, and F. G. Rose, 1992: Annual and interannual variations of earth-emitted radiation based on a 10-year data set. J. Geophys. Res.,97, 12 825–12 835.

  • Cess, R. D., E. F. Harrison, P. Minnis, B. R. Barkstrom, V. Ramanathan, and T. Y. Kwon, 1992: Interpretation of seasonal cloud–climate interactions using Earth Radiation Budget Experiment data. J. Geophys. Res.,97, 7613–7617.

  • ——, and Coauthors, 1995: Absorption of solar radiation by clouds:Observations versus models. Science,267, 496–499.

  • ——, and Coauthors, 1997: Comparison of the seasonal change in cloud-radiative forcing from atmospheric general circulation models and satellite observations. J. Geophys. Res.,102, 16 593–16 603.

  • Chang, P., 1994: A study of the seasonal cycle of sea surface temperature in the tropical Pacific Ocean using reduced gravity models. J. Geophys. Res.,99, 7725–7741.

  • Darnell, W. L., W. F. Staylor, S. K. Gupta, N. A. Ritchey, and A. C. Wilber, 1992: Seasonal variation of surface radiation budget derived from International Satellite Cloud Climatology Project C1 data. J. Geophys. Res.,97, 15 741–15 760.

  • ——, ——, N. A. Ritchey, S. K. Gupta, and A. C. Wilber, 1996: Surface Radiation Budget: A long-term global dataset of shortwave and longwave fluxes. [Available online at http://www.agu.org/eos_elec/95206e.html.].

  • ECMWF Research Department, 1992: Research manual 1: ECMWF data assimilation scientific documentation. ECMWF, Reading, United Kingdom, 88 pp.

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

  • ——, 1982: Atmosphere–Ocean Dynamics. Academic Press, 662 pp.

  • Gilman, D. L., F. J. Fuglister, and J. M. Mitchell, 1963: On the power spectrum of red noise. J. Atmos. Sci.,20, 182–184.

  • Gupta, S. K., 1989: A parameterization for longwave surface radiation from sun-synchronous satellite data. J. Climate,2, 305–320.

  • ——, W. F. Staylor, W. L. Darnell, A. C. Wilber, and N. A. Ritchey, 1993: Seasonal variation of surface and atmospheric cloud radiative forcing over the globe derived from satellite data. J. Geophys. Res.,98, 20 761–20 778.

  • Harrison, E. F., P. Minnis, B. R. Barkstrom, V. Ramanathan, R. D. Cess, and G. G. Gibson, 1990: Seasonal variations of cloud radiative forcing derived from the Earth Radiation Budget Experiment. J. Geophys. Res.,95, 18 687–18 703.

  • Harshvardhan, D. A. Randall, and D. A. Dazlich, 1990: Relationship between the longwave cloud radiative forcing at the surface and the top of the atmosphere. J. Climate,3, 1435–1443.

  • Hartmann, D. L., M. E. Ockert-Bell, and M. L. Michelsen, 1992: The effect of cloud type on earth’s energy balance: Global analysis. J. Climate,5, 1281–1304.

  • Heddinghaus, T. R., and A. F. Krueger, 1981: Annual and interannual variations in outgoing longwave radiation over the tropics. Mon. Wea. Rev.,109, 1208–1218.

  • Houze, R. A., Jr., 1989: Observed structure of mesoscale convective systems and implications for large-scale heating. Quart. J. Roy. Meteor. Soc.,115, 425–461.

  • Jin, F.-F., J. D. Neelin, and M. Ghil, 1994: El Nino on the devil’s staircase: Annual subharmonic steps to chaos. Science,264, 70–72.

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

  • Kessler, W. S., L. M. Rothstein, and D. Chen, 1998: The annual cycle of SST in the eastern tropical Pacific diagnosed in an ocean GCM. J. Climate,11, 777–799.

  • Kiehl, J. T., J. J. Hack, M. H. Zhang, and R. D. Cess, 1995: Sensitivity of a GCM climate to enhanced shortwave cloud absorption. J. Climate,8, 2200–2212.

  • ——, ——, G. B. Bonan, B. A. Boville, B. P. Briegleb, D. L. Williamson, and P. J. Rasch, 1996: Description of the NCAR Community Climate Model (CCM3). NCAR Tech. Note NCAR/TN-420+STR, National Center for Atmospheric Research, Boulder, CO, 152 pp.

  • Klein, S. A., and D. L. Hartmann, 1993: The seasonal cycle of low stratiform clouds. J. Climate,6, 1587–1606.

  • Li, Z., K. Masuda, and T. Takashima, 1993: Estimation of SW surface flux absorbed at the surface from TOA reflected flux. J. Climate,6, 317–320.

  • ——, C. H. Whitlock, and T. P. Charlock, 1995: Assessment of the global monthly mean surface insolation estimated from satellite measurements using global energy balance archive data. J. Climate,8, 315–328.

  • ——, L. Moreau, and A. Arking, 1997: On the solar energy disposition: A perspective from observation and modeling. Bull. Amer. Meteor. Soc.,78, 53–70.

  • Liebmann, B., G. N. Kiladis, J. A. Marengo, T. Ambrizzi, and J. D. Glick, 1999: Submonthly convective variability over South America and the South Atlantic convergence zone. J. Climate,12, 1877–1891.

  • Ma, C.-C., C. R. Mechoso, A. W. Robertson, and A. Arakawa, 1996:Peruvian stratus clouds and the tropical Pacific circulation: A coupled ocean–atmosphere GCM study. J. Climate,9, 1635–1645.

  • Mitchell, T. P., and J. M. Wallace, 1992: The annual cycle in equatorial convection and sea surface temperature. J. Climate,5, 1140–1156.

  • Ohmura, A., and H. Gilgen, 1991: Global Energy Balance Archive (GEBA). World Climate Program Water Project A7 Rep. 2, 60 pp.

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

  • Ramanathan, V., 1987: The role of Earth radiation budget studies in climate and general circulation research. J. Geophys. Res.,92, 4075–4095.

  • ——, B. Subasilar, G. J. Zhang, W. Conant, R. D. Cess, J. T. Kiehl, H. Grassl, and L. Shi, 1995: Warm pool heat budget and shortwave cloud forcing: A missing physics? Science,267, 499–503.

  • Randall, D. A., Harshvardhan, D. A. Dazlich, and T. G. Corsetti, 1989: Interactions among radiation, convection, and large-scale dynamics in a general circulation model. J. Atmos. Sci.,46, 1943–1970.

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

  • ——, and Y.-C. Zhang, 1995: Calculation of surface and top of the atmosphere radiative fluxes from physical quantities based on ISCCP data sets, 2. Validation and first results. J. Geophys. Res.,100, 1167–1197.

  • Salby, M. L., H. H. Hendon, K. Woodberry, and K. Tanaka, 1991: Analysis of global imagery from multiple satellites. Bull. Amer. Meteor. Soc.,72, 467–480.

  • Sherwood, S. C., V. Ramanathan, T. P. Barnett, M. K. Tyree, and E. Roeckner, 1994: Response of an atmospheric general circulation model to radiative forcing of tropical clouds. J. Geophys. Res.,99, 20 829–20 845.

  • Slingo, J. M., and A. Slingo, 1991: The response of a general circulation model to cloud longwave radiative forcing: II. Further studies. Quart. J. Roy. Meteor. Soc.,117, 333–364.

  • Smith, G. L., D. Rutan, T. P. Charlock, and T. D. Bess, 1990: Annual and interannual variations of absorbed solar radiation based on a 10-year data set. J. Geophys. Res.,95, 16 639–16 652.

  • Stephens, G. L., 1996: How much solar radiation do clouds absorb? Science,271, 1131–1133.

  • Stuhlmann, R., and G. L. Smith, 1988: A study of cloud-generated radiative heating and its generation of available potential energy. Part II: Results for a climatological zonal mean January. J. Atmos. Sci.,45, 3928–3943.

  • Tziperman, E., L. Stone, M. A. Cane, and H. Jarosh, 1994: El Nino chaos: Overlapping resonances between the seasonal cycle and the Pacific ocean–atmosphere oscillator. Science,264, 72–74.

  • Wallace, J. M., 1975: Diurnal variations in precipitation and thunderstorm frequency over the conterminous United States. Mon. Wea. Rev.,103, 406–419.

  • Webster, P. J., 1994: The role of hydrological processes in ocean–atmosphere interactions. Rev. Geophys.,32, 427–476.

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

  • Wielicki, B. A., R. D. Cess, M. D. King, D. A. Randall, and E. F. Harrison, 1995: Mission to Planet Earth: Role of clouds and radiation in climate. Bull. Amer. Meteor. Soc.,76, 2125–2153.

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

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