Convectively Coupled Equatorial Waves Simulated by CAMS-CSM
The Chinese Academy of Meteorological Sciences developed a Climate System Model (CAMS-CSM) to participate in the upcoming Coupled Model Intercomparison Project phase 6 (CMIP6). In this study, we assessed the model performance in simulating the convectively coupled equatorial waves (CCEWs) by comparing the daily output of precipitation from a 23-yr coupled run with the observational precipitation data from Global Precipitation Climatology Project (GPCP). Four dominant modes of CCEWs including the Kelvin, equatorial Rossby (ER), mixed Rossby-gravity (MRG), tropical depression-type (TD-type) waves, and their annual mean and seasonal cycle characteristics are investigated respectively. It is found that the space-time spectrum characteristics of each wave mode represented by tropical averaged precipitation could be very well simulated by CAMS-CSM, including the magnitudes and the equivalent depths. The zonal distribution of wave associated precipitation is also well simulated, with the maximum centers over the Indian Ocean and the Pacific Ocean. However, the meridional distribution of the wave activities is poorly simulated, with the maximum centers shifted from the Northern Hemisphere to the Southern Hemisphere, especially the Kelvin, MRG, and TD waves. The seasonal cycle of each wave mode is generally captured by the model, but their amplitudes over the Southern Hemisphere during boreal winter are grossly overestimated. The reason for the excessive wave activity over the southern Pacific Ocean in the simulation is discussed.
Key wordsCAMS-CSM convectively coupled equatorial waves precipitation seasonal cycle model evaluation
Unable to display preview. Download preview PDF.
We thank the anonymous reviewers and the editor for their constructive comments, which significantly improved this paper.
- Griffies, S. M., M. J. Harrison, P. C. Pacanowski, et al., 2004: A Technical Guide to MOM4. GFDL Ocean Group Technical Report No. 5, Princeton, NJ, NOAA/Geophysical Fluid Dynamics Laboratory, 339 pp.Google Scholar
- Huffman, G. J., R. F. Adler, M. M. Morrissey, et al., 2001: Global precipitation at one-degree daily resolution from multisatellite observations. J. Hydrometeor., 2, 36–50, doi: https://doi.org/10.1175/1525-7541(2001)002<0036:GPAODD>2.0.CO;2.CrossRefGoogle Scholar
- Lau, K.-H., and N.-C. Lau, 1990: Observed structure and propagation characteristics of tropical summertime synoptic scale disturbances. Mon. Wea. Rev., 118, 1888–1913, doi: https://doi.org/10.1175/1520-0493(1990)118<1888:OSAPCO>2.0.CO;2.CrossRefGoogle Scholar
- Madden, R. A., and P. R. Julian, 1994: Observations of the 40–50-day tropical oscillation—A review. Mon. Wea. Rev., 122, 814–837, doi: https://doi.org/10.1175/1520-0493(1494)122<0814:OOT-DTO>2.0.CO;2.CrossRefGoogle Scholar
- Nordeng, T. E., 1994: Extended Versions of the Convective Parameterization Scheme at ECMWF and Their Impact on the Mean and Transient Activity of the Model in the Tropics. Technical Memorandum 206, Reading, UK, ECMWF, 41 pp.Google Scholar
- Roundy, P. E., and W. M. Frank, 2004: A climatology of waves in the equatorial region. J. Atmos. Sci., 61, 2105–2132, doi: https://doi.org/10.1175/1520-0469(2004)061<2105:ACOWIT>2.0.CO;2.CrossRefGoogle Scholar
- Straub, K. H., and G. N. Kiladis, 2002: Observations of a convectively coupled Kelvin wave in the eastern Pacific ITCZ. J. Atmos. Sci., 59, 30–53, doi: https://doi.org/10.1175/1520-0469(2002)059<0030:OOACCK>2.0.CO;2.CrossRefGoogle Scholar
- Tiedtke, M., 1989: A comprehensive mass flux scheme for cumulus parameterization in large-scale models. Mon. Wea. Rev., 117, 1779–1800, doi: https://doi.org/10.1175/1520-0493(1989)117>1779:ACMFSF>2.0.CO;2.CrossRefGoogle Scholar
- Ventrice, M. J., C. D. Thorncroft, and M. A. Janiga, 2012a: Atlantic tropical cyclogenesis: A three-way interaction between an African easterly wave, diurnally varying convection, and a convectively coupled atmospheric Kelvin wave. Mon. Wea. Rev., 140, 1108–1124, doi: https://doi.org/10.1175/MWR-D-11-00122.1.CrossRefGoogle Scholar
- Wheeler, M., and G. N. Kiladis, 1999: Convectively coupled equatorial waves: Analysis of clouds and temperature in the wavenumber-frequency domain. J. Atmos. Sci., 56, 374–399, doi: https://doi.org/10.1175/1520-0469(1999)056<0374:CCEWAO>2.0.CO;2.CrossRefGoogle Scholar
- Wheeler, M., G. N. Kiladis, and P. J. Webster, 2000: Large-scale dynamical fields associated with convectively coupled equatorial waves. J. Atmos. Sci., 57, 613–640, doi: https://doi.org/10.1175/1520-0469(2000)057<0613:LSDFAW>2.0.CO;2.CrossRefGoogle Scholar