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ENSO, orographic barriers, and TRMM rainfall along the eastern Andes

Bodo Bookhagen. ENSO, orographic barriers, and TRMM rainfall along the eastern Andes. Geography Department, University of California, Santa Barbara. Rainfall along the Andes – TRMM2B31. Bookhagen and Strecker, 2008. TRMM platform.

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ENSO, orographic barriers, and TRMM rainfall along the eastern Andes

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  1. Bodo Bookhagen ENSO, orographic barriers, and TRMM rainfall along the eastern Andes Geography Department, University of California, Santa Barbara

  2. Rainfall along the Andes – TRMM2B31 Bookhagen and Strecker, 2008

  3. TRMM platform • High-resolution weather parameter measurement between 36°N and 36°S • Several instruments on the platform • Followed by the GPM (Global Precipitation Measurement) project PR Precipitation Radar TMI TRMM Microwave Imager VRS Visible Infrared Scanner LIS Lightning Image Sensor CERES Cloud and Earth’s Radiant Energy System

  4. Calibration – TRMM2B31 Bookhagen and Strecker, 2008

  5. Calibration of TRMM rainfall Bookhagen and Burbank, in review

  6. Validation – TRMM2B31 and TRMM3B42 TRMM 3B42 – combination of several satellite products scaled to match gauge data Bookhagen and Strecker, 2008

  7. Rainfall variations along the Andes

  8. North and south of 17°S – TRMM2B31 elevation asl (km), mean annual rainfall (m/yr), 3-km-relief (km)

  9. North and south of 17°S – TRMM3B42 elevation asl (km), mean annual rainfall (m/yr), 3-km-relief (km)

  10. North and south of 17°S – relief elevation asl (km), mean annual rainfall (m/yr), 3-km-relief (km)

  11. Rainfall along the Andes – all swaths

  12. Rainfall along the Andes – all swaths Río Pastaza Fitzcarrald arch

  13. Rainfall along the Andes – all swaths

  14. Rainfall along the Andes – relief relation

  15. Rainfall along the Andes – relief relation

  16. Rainfall along the Andes – relief relation

  17. Rainfall along the Andes – relief relation

  18. Santa María Basin, NW Argentina (~27°S)

  19. Relief-Rainfall Relationship Simplified geologic structure of eastern Andes margin north of ~17°S Simplified geologic structure of eastern Andes margin at ~25°S

  20. Rainfall in the Andes knee (orocline)

  21. Impact of ENSO on South America

  22. ENSO oscillations BEST index is a combination of (1) an atmospheric component of the ENSO phenomenon (the Southern Oscillation Index or "SOI") and (2) an oceanic component (Nino 3.4 SST, which is defined as the SST averaged over the region 5N-5S and 170W to 120W), defined by Smith and Sardeshmukh, 2000 Note: No change of pos. or neg. ENSO events if Multivariate ENSO Index is used (MEI)

  23. TRMM 3B42 – mean monthly rainfall 3-hr time intervals achieved through a combination of observations from several satellite platforms (TRMM, SSM/I, AMSR, AMSU) data combined with some ground-station data and gridded to 0.25x0.25° ~30x30km)

  24. Validation – TRMM2B31 and TRMM3B42 TRMM 3B42 – combination of several satellite products scaled to match gauge data Bookhagen and Strecker, 2008

  25. TRMM 3B42 – neg. ENSO

  26. TRMM 3B42 – pos. ENSO

  27. TRMM 3B42 – pos. ENSO anomaly

  28. TRMM 3B42 – neg. ENSO anomaly

  29. TRMM 3B42 – neg. ENSO 3-day anomaly • Determining rainfall intensity • analyze the timeseries of each pixel separately (>30,000 measurements) by first calculating cumulative rainfall amounts, which integrate rainfall over the previous 1, 2, 3, or 5-day periods (‘smoothing’) • Identify mean of each pixel timeseries • Count number of events above mean • By varying the integration timescale from 1 to 5 days, we take into account the different storm timescales: we observe that the integration over longer time periods (3 or 5 days) limits the relative storm occurrence to the elevated Andes and the Altiplano-Puna Plateau, suggesting that longer lasting storms occur more frequently there.

  30. TRMM 3B42 – neg. ENSO 5-day anomaly

  31. TRMM 3B42 – neg. ENSO 3-day anomaly

  32. TRMM 3B42 – pos. ENSO 3-day anomaly

  33. TRMM 3B42 – no ENSO 3-day anomaly

  34. Drainage Subbasins of the Amazon

  35. Drainage Subbasins of the Amazon

  36. Drainage Subbasins of the Amazon

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