stratospheric climate and variability of the cmip5 models
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Stratospheric climate and variability of the CMIP5 models. - PowerPoint PPT PresentationTRANSCRIPT
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© University of Reading 2006www.met.reading.ac.uk/research/
stratclim/21 April 2023
Stratospheric climate and variability of the CMIP5 modelsAndrew Charlton-Perez, Mark Baldwin, Thomas Birner, Robert Black, Amy Butler, Natalia Calvo, Nicholas Davis, Edwin Gerber, Nathan Gillett, Steven Hardiman, Junsu Kim, Kirstin Krüger, Yun-Young Lee, Elisa Manzini, Brent McDaniel, Lorenzo Polvani, Thomas Reichler, Tiffany Shaw, Michael Sigmond, Seok-Woo Son, Matthew Toohey, Laura Wilcox, Shigeo Yoden, Bo Christiansen, François Lott, Drew Shindell, Seiji Yukimoto, Shingo Watanabe
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Comparing high-top and low-top CMIP5 models
• Where are there broad differences between high-top and low-top models in CMIP5?
• Look at model performance vs. re-analysis for basic dynamical diagnostics
• Focus on historical runs of the models
• Validation against re-analysis (ERA-Interim and MERRA)
• Red = High-top; Blue = Low-top
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Models usedHigh-Top Max
EMNo.
diagnostics
Low-top Max EM
No. of diagnostic
s
GFDL CM3 5 5 BCC-CSM1.1 3 3
GISS-E2-R 5 5 CCSM4 5 5
GISS-E2-H 15 3 CNRM-CM5 1 4
HadGEM2-CC
3 6 CSIRO-mk3.6.0
10 5
IPSL-CM5A-LR
4 4 GFDL-ESM2M 1 6
IPSL-CM5A-MR
1 4 GFDL-ESM2G 1 1
MIROC-ESM 3 5 HadCM3 10 4
MIROC-ESM-CHEM
1 6 HadGEM2-ES 4 6
MPI-ESM-LR 3 6 INMCM4 1 3
MRI-CGCM3 3 6 MIROC5 4 6
NorESM1-M 3 6
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Metrics
Taylor plotThick – CMIP5 high-topThin – CMIP5 low-topThick dash – CCMVal-2Thin dash – CMIP3
90S-90N, 100-10hPa
Ovals – 2 s.d. sampling intervals for model ensemble
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Temperature biases
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Jet Biases
1975-2005 vs. ERA-Interim
Grey shading - 95% confidence intervalCircles – MERRA climatology
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SSW Frequency/Variance
Variance of 60N and 50hPa DJF zonal mean zonal wind
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Stratosphere-
Troposphere
coupling
Baldwin – ‘dripping paint’ NAM index plots for events when index drops below -3 standard deviations at 10hPa
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Volcanic response
50hPa geopotential height anomaly for two winters following El Chichon and Pinatubo eruptions (only one OND for El Chichon)
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Temperature Trends
Lower stratospheric temperature anomalies compared with RSS SSU datasetModels are processed to have the same weighting function as satellite channelShading shows approx. 5-95% sampling interval for ensemble
Volcano years excluded from bottom plot
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Main conclusions
For models in the CMIP5 ensemble:
1. Mean climate biases in the lower stratosphere is similar for low-top and high-top ensemble,
2. Stratospheric variability is too weak in the low-top ensemble,
3. This has a potential impact on stratosphere-troposphere coupling which is also weaker in the low-top models,
4. The simulation of stratospheric temperature trends is similar in the low-top and high-top ensemble.
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What next?
Some things to think about in the context of DynVar:
1. Can we make progress on persistent biases in both model ensembles (e.g. cold biases in lowermost stratosphere)?
2. Characterising differences in CMIP5 important, but how much does this reflect general low-top/high-top differences?
3. Link between variability and coupling worth exploring in more detail.
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Implications for CMIP6/other experiments
• Likely that many/most models in CMIP6 will include a fully resolved stratosphere – low-top/high-top comparison outdated?
• How do we efficiently characterise stratospheric climate/variability in models.
• Which elements of the stratospheric climate is it necessary to simulate to capture stratosphere-troposphere coupling?
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Extra Slides
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Trends continued
1979-2011Top – obs.Middle – High-top (hatching where observed trends outside range of models)Bottom – Low-top (hatching where low-top and high-top different)
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Tropopause
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Seasonal cycle/Final Warming
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Tropical Upwelling