1 / 26

Genesis Potential Index and ENSO

Genesis Potential Index and ENSO. Suzana J. Camargo. Collaborators:. Kerry A. Emanuel Program in Atmospheres, Ocean and Climate Massachusetts Institute of Technology, Cambridge, MA Adam H. Sobel Department of Applied Physics and Applied Mathematics

jared-mason
Télécharger la présentation

Genesis Potential Index and ENSO

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Genesis Potential Index and ENSO Suzana J. Camargo

  2. Collaborators: • Kerry A. Emanuel Program in Atmospheres, Ocean and Climate Massachusetts Institute of Technology, Cambridge, MA • Adam H. Sobel Department of Applied Physics and Applied Mathematics Department of Earth and Environmental Sciences Columbia University, New York, NY

  3. Motivation • Genesis potential index: dependent on large scale fields developed using statistical fitting to observed genesis of tropical cyclones globally. • Examine how the Genesis potential index describes ENSO – Tropical Cyclone (TC) variability globally. • Comparison with various tropical cyclone indices in different basins. • Possible use in forecasting seasonal TC variability using large scale fields from AGCMs. • Analysis of which variables are responsible for the ENSO response in the Genesis Potential index.

  4. Genesis Potential Index • Refinement of Gray’s tropical cyclone genesis index using Reanalysis data (Emanuel & Nolan 2004). GP= |105η|3/2 (H/50)3 (Vpot/70)3 (1+0.1 Vshear)-2 η= absolute vorticity at 850hPa (s-1) H= relative humidity at 700hPa (%) Vpot = potential intensity (m/s) Vshear = magnitude of the vertical wind shear between 200 and 850hPa (m/s). K.A. Emanuel and D. Nolan, BAMS 85, 667-668 (2004).

  5. Potential Intensity Variables that enter the definition of the potential intensity (taking into account dissipative heating): • SST – sea surface temperature • SLP – sea level pressure • CAPE – convective available potential energy • Atmospherictemperature (various pressure levels) • Mixing ratio(various pressure levels) K.A. Emanuel, JAS 52, 3969-3976 (1995). M. Bister and K.A. Emanuel, Meteor. Atm. Phys. 52, 233-240 (1998)

  6. Genesis Potential Climatology Febr. Sept.

  7. Maximum Genesis Potential Index Climatology

  8. Climatology - Basins Genesis Potential Number of Tropical Cyclones

  9. Genesis Potential Anomalies & ENSOASO (August - October) El Niño La Niña

  10. Genesis Potential Index and ObservationsDifference:El NiñoandLa Niña- ASO Genesis Potential Index Observed Genesis Density

  11. Genesis Potential Index and ObservationsDifference:El NiñoandLa Niña– ASO II Genesis Potential Index Observed Track Density

  12. Genesis Potential Anomalies & ENSOJFM (January-March) El Niño La Niña

  13. Genesis Potential Index and ObservationsDifference:El NiñoandLa Niña- JFM Genesis Potential Index Observed Genesis Density

  14. Genesis Potential Index and ObservationsDifference:El NiñoandLa Niña- JFM Genesis Potential Index Observed Track Density

  15. Interannual Variability - Atlantic

  16. Correlations: Genesis Potential & Number of Tropical Cyclones Eastern North Pacific Atlantic

  17. Correlations: Genesis Potential & Number of Tropical Cyclones

  18. Genesis Potential Index Difference:El NiñoandLa Niña- ASO

  19. Various Correlations:Genesis Potential - South Pacific Number of TC days

  20. Correlations Tropical Cyclone variability indices variables with positive correlation with Genesis Potential Index in various basins: • Number of tropical cyclones • Number of named tropical cyclones • Number of hurricanes • Number of major hurricanes • Number of Tropical Cyclone days (track density) • ACE (Accumulated Cyclone Energy)

  21. Interannual Variability • Consistent highest correlations (for all variables): • South Pacific • Atlantic • Eastern Pacific • Western Pacific • pre-typhoon season (FMA-MJJ) • Eastern Part – year around • Western Part – JFM-AMJ, OND-NDJ, Year • Other basins: specific TC variables for definite seasons, mainly pre or post the peak of the tropical cyclone season. Example: Australian basin: OND - peak JFM. ENSO connection

  22. Variables responsible for ENSO variability Recalculated genesis potential index using climatology for 3 of the 4 variables and varying only the 4th variable. Example: • Vorticity, humidity, potential intensity: climatological values • Vertical wind shear: observed values. Other combinations also tested (2 variables climatology, 2 observed values & 1 variable climatology, 3 observed values).

  23. Genesis Potential – ENSO Difference ASO

  24. Genesis Potential ENSO Variability ASOOne variable observations & 3 variables climatology VORTICITY HUMIDITY Potential Intensity Vertical Wind Shear

  25. Conclusions • Genesis Potential index pattern reproduces well known ENSO effects on TC activity. • Genesis potential index and number of tropical cyclones per basin is correlated in basins with large ENSO influence (South Pacific, Atlantic). • Genesis potential index is correlated with various tropical cyclone activity indices (number of hurricanes, ACE, number of major hurricanes, track density values – number of TC days).

  26. Conclusions II • Most important variables responsible for genesis potential shifts can be identified in different regions: • Atlantic: wind shear (mainly) and SST (PI). • Western North Pacific: combination of humidity, vorticity and wind shear • Eastern North Pacific: wind shear and SST (PI). • Possible application – forecasting TC activity using Genesis Potential index in AGCMs.

More Related