APE Diagnostic Software

Filename:       rossby_wave_activity_flux.gs
Documentation:  rossby_wave_activity_flux.txt

Authors:        Kazuaki Nishii and Hisashi Nakamura
                December 2007
                September 2011 : bug-fix supplied by Kazuaki Nishii

This is a GrADS script for evaluating the horizontal component of a Rossby 
wave activity flux defined by Takaya and Nakamura (2001).  By setting the 
background meridional velocity to be zero, you can evaluate Plumb's (1985) 
flux.  The former is designed for a particular framework where anomalies 
from zonally-varying time-mean flow are regarded as stationary Rossby waves, 
while the latter is suited for representing propagation of planetary waves 
in the zonally-uniform westerlies.

The script was written by Kazuaki Nishii, a postdoc working with Hisashi 
Nakamura.  Hopefully, it is useful for those who are looking at experiments 
with zonally asymmetric SST distributions. The script is designed for our 
application to one of the IPCCC-AR4 models, but you can easily modify it 
for your application to the APE experiments.

Please contact the authors if you have any question on the script.
Hisashi Nakamura <hisashi@eps.s.u-tokyo.ac.jp>


References:

Plumb, R.A.,  1985:  On the Three-Dimensional Propagation of Stationary Waves.  
J. Atmos. Sci., 42, 217-229.
http://dx.doi.org/10.1175/1520-0469(1985)042<0217:OTTDPO>2.0.CO;2

Takaya, K., and H. Nakamura,  2001:  A Formulation of a Phase-Independent 
Wave-Activity Flux for Stationary and Migratory Quasigeostrophic Eddies on 
a Zonally Varying Basic Flow.  J. Atmos. Sci., 58, 608-627.
http://dx.doi.org/10.1175/1520-0469(2001)058<0608:AFOAPI>2.0.CO;2