1. Morphology and forcing of intra-seasonal Kelvin waves in the tropical Atlantic. Irene Polo (Univ. Complutense Madrid) Alban Lazar (LOCEAN-IPSL) Belen Rodriguez-Fonseca (Univ. Complutense Madrid) Sabine Arnault et Gildas Mainsant (LOCEAN-IPSL) I. Morphology Paper in revision for JGRocean II. Forcings

2. SSH Variability Hovmuller diagrams for the 1993-2000 SSH T/P interannual anomalies (cm), equator and northern African coast (left), and equator and southern African coast (right

3. 25-95 day time filtered T/P SSH, equator and N & S coasts Hovmuller diagrams for the time- filtered SLA T/P anomalies (in cm) for the equator and the northern African coast.

4. Speed estimates by Radon transform of 25-95d bpf T/P SSH m/s ~2,5 m/s ~1 m/s ~2 m/s

5. Untill where do the Kelvin waves impact the ssh ? Lagged correlation along the wave tracks of 10-60d bpf T/P SSH

6. Untill where do the Kelvin waves impact the ssh ? Lagged correlation along the wave tracks of 25-95d bpf T/P SSH ~12°N 12°S Remote forcing vanishes

7. Coastal wind forcing dominates poleward of ~12°N/S ~12°N 12°S NORTH r (dSSH/dt OGCM, tau//) ssh and along shore wind stress correlation NORTH r (dSSH/dt obs, tau//) SOUTH r (dSSH/dt OGCM, tau//) SOUTH r (dSSH/dt obs, tau//) 70% variability from local wind low latitude up to 70% variability remotely control Coasts: Local wind forcing dominates Local wind forcing dominates Large remote forcing

8. Figure 3. Climatology of the SSH intraseasonal anomalies (in cm), for observations (shaded areas) and the model (contour lines), along the northern track (left) and the southern track (right). Phase locking: climatology of the bpf T/P SSH A Climatological Intraseasonal Kelvin Wave (CIKW)

9. A Complex EOF analysis of the winter bpf SSH (obs) An Intraseasonal Winter Kelvin Wave (IWKW) mode PC EEOF

10. An Intraseasonal Winter Kelvin Wave (IWKW) mode

11. Equatorial wind forcing : where ? r (dSSH/dt OGCM, tauX) ssh and wind stress correlation @Y=0 r (dSSH/dt obs, tauX) r (dSSH/dt OGCM, tauY) r (dSSH/dt obs, tauY)

12. Equatorial wind forcing : where ? r (dSSH/dt OGCM, tauX) ssh and wind stress correlation @Y=0 r (dSSH/dt obs, tauX) r (dSSH/dt OGCM, tauY) r (dSSH/dt obs, tauY) Eastern equatorial wind not much in control of the situation

13. Equatorial wind forcing : where ? r (dSSH/dt OGCM, tauX) ssh and wind stress correlation @Y=0 r (dSSH/dt obs, tauX) r (dSSH/dt OGCM, tauY) r (dSSH/dt obs, tauY) Western equatorial wind neither in control of the situation Eastern equatorial wind not much in control of the situation OFF-EQUATORIAL FORCING?

14. Western off-equatorial large scale wind forcing : a winter 1998 example Ekman pumping OLR

15. Western off-equatorial large scale wind forcing associated to the IWKW mode: southwestward propagating signal originating in the northern mid-latitudes

16. -coastally trapped waves are among us! they can not hide anymore, thanks to satellite data -winter phase locked intraseasonal KW mode -intraseasonal forcing at basin scale coming from the mid-latitudes ? Perspectives: climact (and biology) impacts: thursday