SLIDE 1
Simulations of the Eastern North Pacific Intraseasonal Variability in CMIP5 GCMs
UCLA
Xianan Jiang
Joint Institute for Regional Earth System Science & Engineering (JIFRESSE) / UCLA Acknowledgment: Eric Maloney (CSU), Frank Li & Duane Waliser (JPL/Caltech) Funding: NOAA Climate Program Office - MAPP Program Jet Propulsion Laboratory / California Institute of Technology
SLIDE 2
- Regional Impacts of ISV over the Eastern Pacific
Caribbean Precipitation (Martin & Schumacher 2011)
βGulf Surge Moisture Eventsβ
North American Monsoon (Lorenz & Hartmann 2006) El Nino Development (Vintzileos et al. 2003) Gap Winds (Maloney & Esbensen 2003) Caribbean Sea LLJ (Serra et al. 2010) El Nino Tropical Cyclone Maloney & Hartmann (2000a,b) Higgins & Shi (2001) Central America Mid-Summer Drought (Magana et al. 1999; Small et al. 2007)
SLIDE 3 Evolution of the leading ISV mode (40-day mode) over the ENP
Shading: Rainfall Vectors: Surface wind
Day 0 3 6 12 9 15 18 21
- Signals from west;
- Enhanced convection
westerly wind anomalies;
- Critical role of latent heat
flux for the ENP ISV (Malonery & Esbensen 2003)
Jiang & Waliser (2008)
Summer mean surface wind
SLIDE 4 day
~ 0.65 deg/day
Jiang & Waliser (2008)
Eastward Propagation of ENP ISV mode
Jiang et al. (2011)
(130-90oW)
Northward Propagation
(5oN-15oN) (10oS-15oN)
day
~ 4 deg/day
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- II. GCM Fidelity in Representing ENP ISV
SLIDE 6
CMIP5 models analyzed in this study
SLIDE 7
Summer Mean Rainfall and 850hPa Winds
SLIDE 8 CSIRO_Mk3 CNRM_CM5 HadCM3 HadGEM2_CC MPI_ESM_LR MRI_CGCM5
Summer mean zonal wind over the ENP warm pool
Westerly Easterly
Summer mean u-wind
OBS
SLIDE 9 Taylor Diagrams for Summer mean rainfall, 850hPa winds
Rain V850 U850
SLIDE 10
STD of 10-90-day filtered rainfall (May-September)
SLIDE 11
Complex EOF (CEOF) analysis
(Barnet 1983; Horel 1984; Maloney et al . 2008)
π½π π = ππ π + π Γ»π π Γ»π π -- quadrature function / Hilbert transform of uj(t) ππ π (j β spatial position; t β time)
TRMM Rainfall
Spatial phase of CEOF1 Spatial amplitude of CEOF1
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Spatial Pattern of CEOF1 Amplitude
SLIDE 13
Spatial Pattern of CEOF1 Phase
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GCM skill for CEOF1 Amplitude and Pattern
(140-80oW; 5oN-25oN)
SLIDE 15 Evolution of Rainfall & 850mb winds of the leading ENP ISV mode
OBS CNRM_CM5 CSIRO_Mk3 Had_GEM2_CC MPI_ESM_LR MRI_CGCM3
SLIDE 16
Eastward Propagation Associated with the ENP ISV
SLIDE 17 GCM skill for CEOF1 Amplitude and Pattern
Westerly or weak easterly mean flow (< 1.5m/s) Strong easterly mean flow (> 4m/s)
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Surface latent heat flux & 850mb winds at day 0
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- III. ENP ISV in future climate
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Changes in Summer Mean Rainfall
SLIDE 21 Spatial Pattern of CEOF1 Amplitude in future climate
CCSM4 HadGEM2_CC HadGEM2_ES MPI_ESM_LR Present Future
Difference
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- Among the sixteen CMIP5 GCMs examined in this study, only seven GCMs
capture the spatial pattern of the leading ENP ISV mode relatively well, although even these several GCMs exhibit biases in simulating ISV amplitude.
- Analyses indicate that model fidelity in representing ENP ISV is closely
associated with ability to simulate a realistic summer mean state. The presence of westerly or weak mean easterly winds over the ENP warm pool region could be conducive for more realistic simulations of the ISV.
- Analyses based on multi-model simulations suggest that the ISV could be
sustained over the ENP basin without the forcing from the eastward propagating MJO over the Indian Ocean / western Pacific.
SLIDE 23
Reference:
Jiang, X., E. Maloney, J.-L. Li, and D. E. Waliser, 2012: Simulations of the Eastern Pacific Intraseasonal Variability in CMIP5 GCMs, J. Climate, accepted pending revisions.
Thank you !
