1. Ken Takahashi, Ph. D. Thermotidal and land-heating forcing of the diurnal cycle of oceanic surface winds in the eastern tropical Pacific* Reunión LMI DISCOH, 29 de marzo, 2012 IMARPE, Callao * Geophysical Research Letters, 39, L04805, doi:10.1029/2011GL050692, 2012

2. Diurnal variation in Quikscat winds (6 am minus 6 pm, local time) Gille et al., 2003

3. “Upsidence wave”: Diurnal cycle in vertical velocity (wave forced by heating of the Andes, Garreaud & Muñoz, 2004) Rahn & Garreaud, 2010

4. Diurnal cycle in surface winds in the tropical Pacific Data: TAO/TRITON Based in diurnal harmonic Ueyama & Deser, 2008 01 Local time 04 Local time 07 Local time 10 Local time 13 Local time

5. Linear theory of the sea breeze (Rotunno, 1983) |Latitude| > 30° : Coastal trapping < 30° : Wave propagation =30° : Singular

6. MM5 v3 simulation (Δx=120 km) (Gayno-Seaman, Grell, CCM2) BC: NNRP Oct. 2008 mean conditions, fixed SST Surface wind diurnal variation (6 am minus 6 pm, local time, m/s) MM5 v3 Takahashi, 2012

7. Simulated diurnal cycle in surface wind and sea level pressure (SLP) (in local time) MM5 v3 Δx=120 km (GS, Grell, CCM2) Takahashi, 2012

8. Migratory diurnal thermal tide Observational estimate Lieberman & Leovy, 1995 Model with tropospheric solar absorption Tidal component in SLP (6 UTC)

9. Trenberth et al., 2009 Global energy budget (Wm -2 )

10. SOLAR RADIATION TERRESTRIAL RADIATION Hartmann 1994 High absorption Atmospheric absorption (%) Visible Near IR Infrared (IR) Atmospheric absorption

11. Absorción atmosférica Gases invernadero Radiación solar Radiación terrestre (infrarrojo) Hartmann, 1994 H2OH2O CO 2 O 2, O 3 CH 4 N2ON2O El vapor de agua es el responsable principal de la absorción de radiación solar en la atmósfera

12. Experiments Control Diurnal land heating suppressed* Absorption of solar radiation (near-IR) by atmospheric water vapor suppressed ** Modeled diurnal amplitude of Land surface temperature SLP *Land-slab layer heat capacity and relaxation time- scale multiplied by 100. ** Corresponding absorption coefficients set to zero in radiation code. b) + c) Takahashi, 2012

13. Modeled diurnal variations in SLP and surface wind ControlThermal tide Extended sea breeze x x x Solar “speed” = 462 m/s ~60 m/s Takahashi, 2012

14. Zonal mean thermal tide Colors:Temperature (°C) Contours: Pressure (hPa) Vectors: (v,w) (m/s, cm/s) MM5 v3 Δx=120 km (GS, Grell, CCM2) Takahashi, 2012

15. Low pressure Radiative air heating West East Sun Equatorward surface wind High pressure Not to scale Migratory atmospheric thermal tide

16. Diurnal cycle off Ica (central-southern coast of Peru) 7 pm LT 11 pm 3 am 7 am11 am 3 pm Maximum Wind (m/s) at 40 m above surface Takahashi et al, in preparation

17. Diurnal anomalies 7 pm LT 11 pm 3 am 7 am11 am 3 pm Wind (m/s) at 40 m above surface Takahashi et al, in preparation

18. Conclusions The diurnal cycle of surface winds has a substantial large-scale contribution (not only “sea breeze”) Atmospheric shortwave absorption by water vapor is an important forcing of this diurnal cycle (thermal tides) Diurnal land-heating produces an important contribution to the diurnal cycle within 2000 km from the coast.