Atmospheric equatorial rossby waves are typically formed (like most convectively coupled waves) from deep convection and they radiate westward from their heating source, often exhibiting a pronounced axisymmetric equatorial structure with gyres of the same sign (cyclonic or anticyclonic) straddling the equator, the speed of these waves is a function of distance from the equator, with faster westerly propagation closer to the equator and vis versa and on average they travel at about a third of the speed of a Kelvin Wave. In the case where twin cyclones are axissymmetric wrt the equator and propagating westward as an equatorial Rossby Wave, they produced westerly wind anomalies at the surface which disrupts the wind-gravity balance in the equatorial Pacific, ultimately producing a Kelvin Wave in order to restore this balance because the eastward wind is slower. Zonal advective feedbacks, those related to convection, and the underlying "elasticity" of the thermocline (in our current climate) all contribute to non-linearities in the system wherein the contribution from anomalous westerly wind of the same magnitude and duration as a corresponding easterly wind anomaly will actually push the equatorial Pacific slightly towards El Nino instead of being dead-on neutral. It's one major reason why even in years like 2014 which had one pronounced westerly wind burst over a period of several months which were actually dominated by easterlies still ended up w/ net +SSTAs in the Eq Pacific. In a warmer climate where the static stability of the upper ocean increases due to disproportionate warming rates in the upper vs middle-deep oceans actually stiffen the thermocline and dampen non-linearities that currently exist in the system, such that the strongest El Ninos will actually be as strong as the largest La Ninas instead of today where we find "Super" Ninos like 1877-78, 1982-83, & 1997-98 having greater amplitude over monster La Nina events like 1973-74, 1916-17, etc
Thanks for the explanation. Which charts do you find best to track these equatorial rossby waves? I know the kelvin waves can be seen with the anomalously warm ocean temperatures propagating eastwards.