DRAFT       WGNE STANDARD DIAGNOSTICS OF VARIABILITY       DRAFT

 


Note: Some variance and eddy statistics are included in the

      WGNE Standard Diagnostics of the Mean Climate

http://www-pcmdi.llnl.gov/amip/OUTPUT/WGNEDIAGS/wgnediags.html

 

Intraseasonal Variability

  29-70 day bandpassed 200 hPa velocity potential, averaged 5N to 5S, Hovm÷ller (time vs longitude). Abscissa 0 to 360 longitude. Plot 1986, 1987, 1988 and other selected years, one year per plot.

      Ex: Fig 1 of Innes and Gregory (1995) and Fig 1 of Reynolds et al. (1995).


Madden-Julian Oscillation (MJO)

  1) Time series of daily zonal mean 10N-10S averaged 200hPa zonal wind and low-pass filtered

      Ex: Fig 2, top panel of Slingo et al. (1999)

  2) MJO index - (100 day running variance of 20-100 day band-pass filtered zonal averaged 10N-10S averaged 200hP zonal wind averaged 10N-10S.

      Ex: Fig 3, solid line of Slingo et al. (1999)


El Ni˝o - Southern Oscillation (ENSO)

  Hovm÷ller (time vs longitude) diagram of monthly mean anomalies (relative to AMIP II period: 1979-1995) in the tropical Pacific, averaged between 5S and 5N for precipitation, OLR, and 850 mb zonal wind. Abscissa 100E to 80W. Plots can extend beyond the period providing the climatological averages from which the anamolies are computed.

      Ex: Fig 3, Lo et al. (1995) and Fig 4 van den Dool et al. (1995).


Blocking

  Blocking index as defined in D'Andrea et al. (1998)

  1) DJF blocking frequency (%) as function of longitude

      Ex: Fig 4 of D'Andrea et al. (1998)

  2) Hovm÷ller diagram, DEC-DEC vs longitude

      Ex: Fig 5 of D'Andrea et al. (1998)


Wavenumber-Frequency plots

  Zonal wavenumber-frequency power spectra calculated from 6 hourly data (summed 15S to 15N) for antisymmetric and symmetric component of u at 850 and 200 mb, omega at 500 mb OLR and precip.

  1) Raw power spectra

      Ex: Fig 1 of Wheeler and Kiladis (1999)

  2) Spectra with background removed

      Ex: Fig 2 of Wheeler and Kiladis (1999)


Histograms

  Averaged daily precipitation rate, for all grid points 10N-10S, 30N-60N land, 30N-60N ocean.

By classes

       Ex: Fig 10 of Inness et al. (2001), except classes and regions differ.


Seasonal Cycle

  Horizontal maps of climatological average monthly average amplitude (max-min) and phase (Month of max, and Month of min) of Precip and T2m.

     Ex: Fig 3 of Yang and Slingo (2001) which shows similar plot for Diurnal cycle.  
    Note: Phase is plotted using ``circular'' color table without contours,    
    i.e. 1$\rightarrow$12 by blue$\rightarrow$green$\rightarrow$red$\rightarrow$purple($\rightarrow$blue)


Diurnal Cycle

  Horizontal maps of climatological average amplitude and phase (local time of max) of diurnal harmonic of precip and T2m, calculated based on Fourier analysis of climatological average of 3-hourly samples.

      Ex: Fig 3 of Yang and Slingo (2001).  
    Note: Phase is plotted using ``circular'' color table without contours,    
    i.e. 1$\rightarrow$24 by blue$\rightarrow$green$\rightarrow$red$\rightarrow$purple($\rightarrow$blue)


Atmospheric Angular Momentum

  Global average, monthly average vs time. (Defined as in WGNE Standard Diagnostics of Mean Climate, 2. Global Averages)

      Ex: Fig 2 of Hide et al. (1997)


Modes of Variability

  (1) Pacific sector (20-80N, 120E-90W) first and second EOF of monthly mean 500 mb height field during four winter months (Dec-Mar) and percent variance explained. (Plots of nondimensional normalized EOF multiplied by the square root of the corresponding EOF variance to obtain the dimensional standard deviation of 500 mb height field at each grid point associated with the EOF.

      Ex: Figs 1 and 3 of Saravanan (1998)

  (2) Atlantic sector (20-80N, 90W-30E) first and second EOF of monthly mean 500 mb height field during four winter months (Dec-Mar) and four summer months (Jun-Sep) and percent variance explained. (Plots of nondimensional normalized EOF multiplied by the square root of the corresponding EOF variance to obtain the dimensional standard deviation of 500 mb height field at each grid point associated with the EOF.

      Ex: Fig 4 of Saravanan (1998)

  (3) Squared correlation (%) between tropical Atlantic SST and precipitation averaged over northern Nordeste Brazil (11-3S, 46-38W) for MAM season. (dashed contours where correlations are negative before squaring)

      Ex: Fig 2 of Saravanan and Chang (2000)

  (4) Southern Hemisphere (30-90S) first and second EOF of monthly mean 500 mb height field during four winter months (Jun-Sep) and percent variance explained. (Plots of nondimensional normalized EOF multiplied by the square root of the corresponding EOF variance to obtain the dimensional standard deviation of 500 mb height field at each grid point associated with the EOF.

      Ex: Figs 8.3a and b of Kiladis and Mo (1998)          and
        Figs 1 and 2 of Rogers and van Loon (1982)

REFERENCES

D'Andrea, F., S. Tibaldi, M. Blackburn, G. Boer, M. DÚquÚ, M. R. Dix, B. Dugas, L. Ferranti, T. Iwasaki, A. Kitoh, V. Pope, D. Randall, E. Roeckner, D. Straus, W. Stern, H. van den Dool and D. Williamson, 1997: Northern Hemisphere Atmospheric Blocking as simulated by 15 Atmospheric General Circulation Models in the period 1979-1988. Clim. Dynamics, 14, 385-407.

Hide, R., J. O. Dickey, S. L. Marcus, R. D. Rosen and D. A. Salstein, 1997: Atmospheric angular momentum fluctuations during 1979-1988 simulated by global circulation models. J. Geophys. Res., 102, 16,423-16,438.

Innes, P.M. and D. Gregory, 1995: Analysis of tropical intraseasonal variability in the U.K. Met. Office Unified Model. Proceedings of the First International AMIP Scientific Conference, WMO/TD-N0.732, 131-136.

Inness, P. M., J. M. Slingo, S. J. Woolnough, R. B. Neale and V. D. Pope, 2001: Organization of tropical convection in a GCM with varying vertical resolution; implications for the simulation of the Madden-Julian Oscillation. Clim. Dynamics, 17, 777-794.

Kiladis and Mo, 1998: Interannual and Intraseasonal Variability in the Southern Hemisphere. Chapter 8 of Meteorology of the Southern Hemisphere, Ed. D. J. Karoly and D. G. Vincent. Meteorology Monographs, Vol. 27, No. 49, American Meteorological Society, 307-336.

Lo, K.-w., A. D. Del Genio, 1995: Evaluation of the New Giss GCM. Proceedings of the First International AMIP Scientific Conference, WMO/TD-N0.732, 283-288.

Reynolds, C., R. Gelaro and T. Murphree, 1995: Intraseasonal Variability in a 10-year integration of the Navy operational global atmospheric prediction system. Proceedings of the First International AMIP Scientific Conference, WMO/TD-N0.732, 143-148.

Rogers, J. C., and H. van Loon, 1982: Spatial Variability of Sea Level Pressure and 500 mb Height Anomalies over the Couthern Hemisphere. Mon. Wea. Rev., 110, 1375-1392.

Saravanan, R., 1998: Atmospheric Low-Frequency Variability and Its Relationship to Midlatitude SST Variability: Studies Using the NCAR Climate System Model. J. Climate, 11, 1386-1404.

Saravanan, R., and P. Chang, 2000: Interaction between Tropical Atlantic Variability and El Ni˝o-Southern Oscillation. J. Climate, 13, 2177-2194.

Slingo, J. M., D. P. Dowell, K. R. Sperber and F. Nortley, 1999: On the predictability of the interannual behavior of the Madden-Julian oscillation and its relationship with El Ni˝o. Quart. J. Roy. Meteor. Soc., 125, 583-509.

van den Dool, H. M., S. Saha, J. Schemm and W. Ebisuzaki, 1995: A Multi-Year Climate Run with the NCEP/NCAR Reanalysis Model. Proceedings of the First International AMIP Scientific Conference, WMO/TD-N0.732, 289-294.

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. Yang, G.-Y. and J. Slingo, 2001, The Diurnal Cycle in the Tropics, Mon. Wea. Rev., 129, 784-801.