Benjamin A. Schenkel ( bschenkel@albany.edu ) 1 , Lance F. Bosart 1 , Daniel Keyser 1 , and Robert E. Hart 2 1 Univers

1. The Role of Tropical Cyclones in Cross-Equatorial Total Energy Transports Benjamin A. Schenkel (bschenkel@albany.edu)1, Lance F. Bosart1, Daniel Keyser1, and Robert E. Hart2 1University at Albany, SUNY 2The Florida State University Tropical Lunch – 1/24/2014 Research Sponsored by NSF Atmospheric and Geospace Sciences Postdoctoral Research Fellowship

2. Motivation • Background • Results • Summary Motivation: Typhoon Dianmu (2004) Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

3. Motivation • Background • Results • Summary Motivation: Typhoon Dianmu (2004) Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

4. Motivation • Background • Results • Summary Motivation: Typhoon Dianmu (2004) Do TCs transport significant quantities of energy across the equator? Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

5. Motivation • Background • Results • Summary • Background Review of Upper-Tropospheric TC Structure • Composite of 200 hPa wind speed (m s−1; contours)and streamlines for North Atlantic TCs • Generation of anticyclone aloft due to latent heat release from convection • Flow is divergent and asymmetric with strongest wind speeds found in equatorward TC outflow jet • Location of outflow jet depends on characteristics of large-scale flow North Do equatorward TC outflow jets transport significant quantities of total energy across the equator? Merrill (1988) East Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY 8/41

6. Motivation • Background • Results • Summary Methodology: Quantifying Cross-Equatorial Energy Transports by TCs • Evaluation of mean equatorward energy transports by TCs utilizes three-dimensional composites centered only on TC longitude using atmospheric reanalysis data • Composites are constructed using NCEP Climate Forecast System Reanalysis (Saha et al. 2010) for TCs (maximum 10-m wind speed ≥ 34 kt) in western North Pacific at or equatorward of 20°N from 1979–2010 (N = 696 TCs) • Composites of raw anomalies and normalized anomalies are used to isolate role of TCs in meridional energy transports Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

7. Motivation • Background • Results • Summary Methodology: Quantifying Cross-Equatorial Energy Transports by TCs • Composited vertically integrated meridional energy transports (Trenberth et al. 1997) are used to assess role of TCs in cross-equatorial energy transports: • Term 1:Vertically integrated meridional total energy transports • Term 2: Vertically integrated meridional kinetic energy transports • Term 3: Vertically integrated meridional latent energy transports • Term 4: Vertically integrated meridional sensible heat transports • Term 5: Vertically integrated meridional potential energy transports (1) (2) (3) (4) (5) Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

8. Motivation • Background • Results • Summary Vertically Integrated Meridional Total Energy Transports due to TCs • Meridional energy transports by TC in deep tropics due to two factors: Blue/Dashed: Southward transport Red/Solid: Northward transport Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

9. Motivation • Background • Results • Summary Vertically Integrated Meridional Total Energy Transports due to TCs • Meridional energy transports by TC in deep tropics due to two factors: • Cyclonic circulation of TC Blue/Dashed: Southward transport Red/Solid: Northward transport Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

10. Motivation • Background • Results • Summary Vertically Integrated Meridional Total Energy Transports due to TCs • Meridional energy transports by TC in deep tropics due to two factors: • Cyclonic circulation of TC • Upper-tropospheric equatorward TC outflow jet on southeastern flank of anticyclonic circulation of TC Blue/Dashed: Southward transport Red/Solid: Northward transport Next, we will examine meridional transport anomalies in environment outside of TC using domain extending across entire globe… Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

11. Motivation • Background • Results • Summary Horizontal Structure of Global Meridional Energy Transport Anomalies • TC and surrounding environment appear to be dominant features in composites near equator Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

12. Motivation • Background • Results • Summary Horizontal Structure of Global Meridional Energy Transport Anomalies • Next, to quantify meridional total energy anomalies during TC passage, composites are zonally integrated over area encompassing: • TC and its immediate environment (Near TC) • Environment outside of TC (Outside TC) • All longitudes including TC and its outer environment (Total) • Absence of significant meridional transports outside of TC within composites suggesting TC is dominant feature Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

13. Motivation • Background • Results • Summary Horizontal Structure of Global Meridional Energy Transport Anomalies • Next, to quantify meridional total energy anomalies during TC passage, composites are zonally integrated over area encompassing: • TC and its immediate environment (Near TC) • Environment outside of TC (Outside TC) • All longitudes including TC and its outer environment (Total) • Absence of significant meridional transports outside of TC within composites suggesting TC is dominant feature Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

14. Motivation • Background • Results • Summary Quantifying Meridional Energy Transports by TCs in a Global Context • Anomalous meridional total energy transports from Northern Hemisphere tropics into Northern Hemisphere subtropics and Southern Hemisphere tropics • Energy convergence • Energy divergence large-scale response of environment to TC passage similar to TC Yuri • Energy convergence Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

15. Motivation • Background • Results • Summary Horizontal Structure of Global Meridional Energy Transport Anomalies • Next, to quantify meridional total energy anomalies during TC passage, composites are zonally integrated over area encompassing: • TC and its immediate environment (Near TC) • Environment outside of TC (Outside TC) • All longitudes including TC and its outer environment (Total) • Absence of significant meridional transports outside of TC within composites suggesting TC is dominant feature Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

16. Motivation • Background • Results • Summary Quantifying Meridional Energy Transports by TCs in a Global Context • Meridional transports by outside environment nearly balance meridional transports by TC large-scale response of environment to TC passage similar to TC Yuri Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

17. Motivation • Background • Results • Summary Horizontal Structure of Global Meridional Energy Transport Anomalies • Next, to quantify meridional total energy anomalies during TC passage, composites are zonally integrated over area encompassing: • TC and its immediate environment (Near TC) • Environment outside of TC (Outside TC) • All longitudes including TC and its outer environment (Total) • Absence of significant meridional transports outside of TC within composites suggesting TC is dominant feature Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

18. Motivation • Background • Results • Summary Quantifying Meridional Energy Transports by TCs in a Global Context • Zonal integration over all longitudes yields southward energy transports near equator suggesting transports by TCs are dominant • Southward transport anomalies of −0.5 PW by TC are ~25% to ~50% of climatological southward transports at equator in August and September (e.g., Trenberth et al. 2003) large-scale response of environment to TC passage similar to TC Yuri Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

19. Motivation • Background • Results • Summary Conceptual Model of TC Impacts on Meridional Energy Transports Late Summer Zonal Mean Meridional Circulation p 30°S 15°S 0 15°N 30°N Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

20. Motivation • Background • Results • Summary Conceptual Model of TC Impacts on Meridional Energy Transports Late Summer Zonal Mean Meridional Circulation with a Western North Pacific TC TC p 30°S 15°S 0 15°N 30°N Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

21. Motivation • Background • Results • Summary Conceptual Model of TC Impacts on Meridional Energy Transports Late Summer Zonal Mean Meridional Circulation with a Western North Pacific TC TC p Heat and moisture 30°S 15°S 0 15°N 30°N • Enhanced northward lower-tropospheric transports of heat and moisture by TC Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

22. Motivation • Background • Results • Summary Conceptual Model of TC Impacts on Meridional Energy Transports Late Summer Zonal Mean Meridional Circulation with a Western North Pacific TC TC Heat and potential energy p Heat and moisture 30°S 15°S 0 15°N 30°N • Enhanced northward lower-tropospheric transports of heat and moisture by TC • Enhanced southward upper-tropospheric transports of heat and potential energy by equatorward TC outflow jet Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

23. Motivation • Background • Results • Summary Conceptual Model of TC Impacts on Meridional Energy Transports Late Summer Zonal Mean Meridional Circulation with a Western North Pacific TC TC Heat and potential energy Net southward energy transport p Heat and moisture 30°S 15°S 0 15°N 30°N • Net southward vertically integrated total energy transports across equator by TC Do western North Pacific TCs play a significant role in aggregate equatorward total energy transports? Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

24. Motivation • Background • Results • Summary Future Work: Meridional Transports by TCs in Other Basins? North Atlantic (N = 204 TCs) Western North Pacific (N = 696 TCs) Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

25. Motivation • Background • Results • Summary Future Work: Meridional Transports by TCs in Other Basins? Eastern North Pacific (N = 487 TCs) Western North Pacific (N = 696 TCs) • Cross-equatorial energy transports by TCs in other basins do not appear to be as substantial as western North Pacific Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY

26. Motivation • Background • Results • Summary • Background Review of Upper-Tropospheric TC Structure • Composite of 200 hPa wind speed (m s−1; contours)and streamlines for North Atlantic TCs • Generation of anticyclone aloft due to latent heat release from convection • Flow is divergent and asymmetric with strongest wind speeds found in equatorward TC outflow jet • Location of outflow jet depends on characteristics of large-scale flow Heat and potential energy North Merrill (1988) East Cross-Equatorial Energy Transports by TCs Benjamin A. Schenkel University at Albany, SUNY 8/41