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Tropical East Pacific Synoptic Variability in NCEP Reanalyses 1 and 2: Comparisons With TAO Winds

Tropical East Pacific Synoptic Variability in NCEP Reanalyses 1 and 2: Comparisons With TAO Winds. Presented by Yolande Serra, University of Arizona. EPIC Workshop 11-13 May 2005 APL, UW. TAO buoys used for this study. CMAP 79-02 A month : JAS. 20N. 10N. 0. 10S. 20S. 140E. 180. 140W.

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Tropical East Pacific Synoptic Variability in NCEP Reanalyses 1 and 2: Comparisons With TAO Winds

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  1. Tropical East Pacific Synoptic Variability in NCEP Reanalyses 1 and 2:Comparisons With TAO Winds Presented by Yolande Serra, University of Arizona EPIC Workshop 11-13 May 2005 APL, UW

  2. TAO buoys used for this study CMAP 79-02 Amonth: JAS 20N 10N 0 10S 20S 140E 180 140W 100W 60W 20W In Situ TAO Data • Native 10-min data smoothed to hourly, then sub-sampled to 4xdaily to match NCEP Reanalyses. • All available wind data from June-November 1990-2003.

  3. NCEP/NCAR and NCEP/DOE Reanalyses • 2.5°x2.5°, 4xdaily 1000 mb winds • June-November 1990-2003 time period to match TAO data availability. • TAO data are incorporated into both products to the extent allowed by the model data assimilation routine (!)

  4. Model Configurations (adopted from Hodges et al. 2003)

  5. NCEP/NCAR (RA1) vs. NCEP/DOE (RA2) NCEP/NCAR (RA1) vs. TAO - V-wind Power Spectra NCEP/DOE (RA2) vs. TAO - V-wind Power Spectra 9°N 140°W 5°N 140°W 9°N 140°W 5°N 140°W 2°N 140°W 0°N 140°W 2°N 140°W 0°N 140°W 2°S 140°W 5°S 140°W 2°S 140°W 5°S 140°W Cycles per day Cycles per day Cycles per day Cycles per day 4-day

  6. 8°N 125°W 5°N 125°W 8°N 125°W 5°N 125°W 2°N 125°W 0°N 125°W 2°N 125°W 0°N 125°W 2°S 125°W 5°S 125°W 2°S 125°W 5°S 125°W 8°S 125°W 8°S 125°W Cycles per day Cycles per day 4-day Cycles per day Cycles per day NCEP/NCAR (RA1) vs. NCEP/DOE (RA2) NCEP/NCAR (RA1) vs. TAO - V-wind Power Spectra NCEP/DOE (RA2) vs. TAO - V-wind Power Spectra

  7. 4-day NCEP/NCAR (RA1) vs. NCEP/DOE (RA2) NCEP/NCAR (RA1) vs. TAO - V-windCoherence2 and Phase NCEP/DOE (RA2) vs. TAO - V-windCoherence2 and Phase 9°N 140°W 5°N 140°W 9°N 140°W 5°N 140°W 2°N 140°W 0°N 140°W 2°N 140°W 0°N 140°W 2°S 140°W 5°S 140°W 2°S 140°W 5°S 140°W Cycles per day Cycles per day Cycles per day Cycles per day

  8. SDOM NCEP/NCAR (RA1) vs. NCEP/DOE (RA2) NCEP/NCAR (RA1) vs. TAO - U,V-wind Biases and Correlations NCEP/DOE (RA2) vs. TAO - U,V-wind Biases and Correlations 9°N 140°W 5°N 140°W 9°N 140°W 5°N 140°W 2°N 140°W 0°N 140°W 2°N 140°W 0°N 140°W 2°S 140°W 5°S 140°W 2°S 140°W 5°S 140°W U V U V U V U V

  9. 1990-2003 Mean Bias in Eastern Tropical Pacific - rough estimates!

  10. NCEP/NCAR (RA1) vs. NCEP/DOE (RA2) 850 mb winds regressed onto TD-filtered OLR at 7.5N, 130W, June-November 1979-2002

  11. NCEP/NCAR advection of meridional eddy momentum by eddy winds at 1000 mb NCEP/NCAR meridional eddy advection by eddy winds at 1000 mb Momentum lost by eddies Momentum gained by eddies Synoptic-scale u’·Hv’ is ~8x10-5 m s-2 ∂(v’v’)/∂y [m s-2]

  12. Comparison of synoptic waves in AGCMs - Hodges et al (2003) NCEP/NCAR NCEP/DOE Track density distributions of EWs

  13. Less variance at synoptic frequencies. Large diurnal variability at some locations. Significant coherence and in phase with TAO at synoptic and lower frequencies. Potentially large differences in mean wind components. Greater or equal amount of variance at synoptic frequencies. Significant coherence but out of phase by as much as a quarter cycle (~1 day) at synoptic frequencies. Potentially large differences in mean wind components. Summary of Comparisons with TAO RA1 RA2

  14. NCEP/NCAR (RA1) vs. NCEP/DOE (RA2) NCEP/NCAR (RA1) vs. TAO - U-wind Power Spectra NCEP/DOE (RA2) vs. TAO - U-wind Power Spectra 9°N 140°W 5°N 140°W 9°N 140°W 5°N 140°W 2°N 140°W 0°N 140°W 2°N 140°W 0°N 140°W 2°S 140°W 5°S 140°W 2°S 140°W 5°S 140°W Cycles per day Cycles per day Cycles per day Cycles per day 4-day

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