assessing radiative fluxes in the climate system from
TRANSCRIPT
ETH
Assessing radiative fluxes in the climate system from surface and space
Libera Science team meeting Nov 16, 2020
Martin WildETH Zurich, Switzerland
With support from Doris Folini, Maria Hakuba, Matthias Schwarz, Chuck Long, Su
Yang, Richard Allen, Norman Loeb, Seiji Kato
ETH
Units Wm-2
Surface fluxes considering information from surface station observations
Earth Radiation Budget
Updated from IPCC AR5 / Wild et al. 2013, 2015 Climate Dynamics
TOA fluxes from CERES satellite observations
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Shortwave radiation budgets in CMIP6 GCMsReflected shortwave radiation TOA
Downward shortwave radiation surface
Model range: 13 Wm-2
Variance: 2.7 Wm-2
Mean CMIP6: 101 Wm-2
CERES EBAF: 100 Wm -2
Model range: 21 Wm-2
Variance: 4.5 Wm-2
Mean CMIP6: 187 Wm-2
Wild et al 2015: 185 Wm-2
global means of 38 CMIP6 models
global means of 38 CMIP6 models
Wild 2020 Climate Dynamics
CERES-EBAF
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Longwave radiation budgets in CMIP6 GCMsOutgoing longwave radiation TOA
Downward longwave radiation surface
Model range: 16 Wm-2
Variance: 2.8 Wm-2
Mean CMIP6: 238 Wm-2
CERES EBAF: 239 Wm -2
Model range: 20 Wm-2
Variance: 5.2 Wm-2
Mean CMIP6: 344 Wm-2
Wild et al 2015: 342 Wm-2
global means of 38 CMIP6 models
global means of 38 CMIP6 models
Wild 2020 Climate Dynamics
CERES-EBAF
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• Worldwide measurements of historic energy fluxes at the surface (2500 sites)
• Recordsa at many sites since 1950s, some back to 1930s • Monthly mean values
• WCRP initiative, starting in 1992• Highest measurement quality at selected sites worldwide
(currently 51 anchor sites) • Minute values
Wild et al. 2017, ESSD
Loeb et al, 2018 J. Climate
TOA / Surface radiation observations
www.bsrn.awi.de
www.geba.ethz.ch
• monthly and climatological observed TOA all-sky, clear-sky (spatially complete), and cloud radiative effect (CRE) fluxes
• 1° x 1°spatial resolution • Edition 4.1
CERES EBAF
Ohmura et al. 1998 BAMSDriemel et al. 2018 ESSD
www.bsrn.awi.de
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Atmospheric SW Absorption over EuropeCombination of collocated TOA SW Absorption from CERES EBAF and surface SW absorption from GEBA/MODIS at 137 GEBA sites in Europe
Fractional Atmospheric SW Absorption: 23 % (robust through seasons and latitudes)
Hakuba et al. JGR 2014Hakuba, M. Z., D. Folini, G. Schaepman-Strub, and M. Wild (2014), Solar absorption over Europe from collocated surface and satellite observations, J. Geophys. Res. Atmos., 119, 3420–3437
(% of TOA isolation)
CERES EBAF
GEBA/MODIS
TOA
Atmosphere
Surface
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Estimating clear-sky climatologies at BSRN sites
SW clear sky detection algorithmLong and Ackerman (2002) JGRTakes into account magnitude and temporal variability of diffuse and total downward solar radiation
LW clear sky detection algorithmLong and Turner (2008) JGRMakes use of clear episodes detected by theSW algorithm and takes into account variabilityof downward longwave radiation, measured ambient air temperature and effective sky brightness temperature.
Clear sky BSRN data processed at ETH Zurichby Maria Hakuba in collaboration with Chuck Long
High resolution BSRN records (minute data) used to establish clear sky estimates
__ observed__ GCMs
BSRN site Payerne Switzerland
Wild et al. 2019
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Earth Radiation Budget without clouds
Wild M, Hakuba M, Folini D, Ott P, Schär C, Kato S, Long C, 2019: Climate Dynamics 52, 4787-4812
Global mean surface clear sky fluxes BSRN observations + climate models
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Clear sky TOA fluxes from CERES EBAF
Earth Radiation Budget without clouds
adjusted for GCM-type clear sky
Wild M, Hakuba M, Folini D, Ott P, Schär C, Kato S, Long C, 2019: Climate Dynamics 52, 4787-4812
Global mean surface clear sky fluxes BSRN observations + climate models
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Clear sky TOA fluxes from CERES EBAF
73 Wm-2
Combining SW clear sky TOA and surface absorption to obtain atmospheric clear sky SW absorption of 73 Wm-2
Earth Radiation Budget without clouds
adjusted for GCM-type clear sky
Wild M, Hakuba M, Folini D, Ott P, Schär C, Kato S, Long C, 2019: Climate Dynamics 52, 4787-4812
cf. CERES EBAF Ed473 Wm-2 (Kato et al. 2018)
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Clear sky atmospheric SW absorption in CMIP6
Ø Clear-sky atmospheric SW absorption in CMIP6 multimodel mean in perfect agreement with reference estimates
Ø 35 out of 38 models within 2 Wm-2 of reference estimates
40 models
global means of 38 CMIP6 models
Wild 2020 Climate Dynamics
Model range: 8 Wm-2
Variance: 1.8 Wm-2
Mean CMIP6: 73 Wm-2
Wild et al 2019 : 73 Wm -2Kato et al 2018 : 73 Wm -2
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Atmospheric clearsky SW Absorption: Historic evolution
Climate model Generation Atmos. clear sky SW absorptionMultimodel global mean
Pre AMIP (late 1980s models) 63 Wm-2
AMIP II (1990s models) 67 Wm-2
CMIP3 (early 2000s) 69 Wm-2
CMIP5 (2010s) 70 Wm-2
CMIP6 (2020s) 73 Wm-2
Reference values 73 Wm-2 (Wild et al. 2019)73 Wm-2 (Kato et al. 2018)
Wild 2020 Climate Dynamics
Upward adjustment by 10 Wm-2 over model generations in line with recent reference estimates
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All sky Clear sky
Wild et al 2015 Clim. Dyn.
Cloud radiative effects (CRE)
Wild et al 2019 Clim. Dyn.
Units Wm-2 SW CRE LW CRE Net CRE
TOA -47 28 -19Atmosphere 7 0 7Surface -54 28 - 26
Wild et al. 2019 Clim Dyn / Wild 2020 Clim Dyn
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All sky Clear sky
Wild et al 2015 Clim. Dyn.
Cloud radiative effects (CRE)
Wild et al 2019 Clim. Dyn.
Units Wm-2 SW CRE LW CRE Net CRE
TOA CMIP6 -47 -48 28 24 -19 -24Atmosphere CMIP6 7 3 0 -1 7 2Surface CMIP6 -54 -51 28 26 - 26 -25
Wild et al. 2019 Clim Dyn / Wild 2020 Clim Dyn
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Collocated SW changes at the surface and TOA
Downward Surface Solar Composite of 84 observation sites
ChinaCompositeof 84 sites
Schwarz et al. 2020 Nature Geoscience
1965-2015
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Collocated SW changes at the surface and TOA
Absorbed TOACERES / DEEP-C
Downward Surface Solar Composite of 84 observation sites
ChinaCompositeof 84 sites
1985 - 2015
Schwarz et al. 2020 Nature Geoscience
1965-2015
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Collocated SW changes at the surface and TOA
Surface AlbedoGLASS-AVHRR/MODIS
Downward Surface Solar Composite of 84 observation sites
ChinaCompositeof 84 sites
Absorbed TOACERES / DEEP-C
1985 - 2015
Schwarz et al. 2020 Nature Geoscience
1965-2015
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Collocated SW changes at the surface and TOA
Absorbed SurfaceDownward solar x (1-albedo)
Surface AlbedoGLASS-AVHRR/MODIS
Downward Surface Solar Composite of 84 observation sites
ChinaCompositeof 84 sites
Absorbed TOACERES / DEEP-C
1985 - 2015
Schwarz et al. 2020 Nature Geoscience
1965-2015
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Collocated SW changes at the surface and TOA
Absorbed TOACERES / DEEP-C
Absorbed AtmosResidual TOA - Surface
Absorbed SurfaceDownward solar x (1-albedo)
Surface AlbedoGLASS-AVHRR/MODIS
Downward Surface Solar Composite of 84 observation sites
ChinaCompositeof 84 sites
1985 - 2015
Schwarz et al. 2020 Nature Geoscience
1965-2015
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Collocated SW changes at the surface and TOA
Absorbed TOACERES / DEEP-C
Absorbed AtmosResidual TOA - Surface
Absorbed SurfaceDownward solar x (1-albedo)
Surface AlbedoGLASS-AVHRR/MODIS
Downward Surface Solar Composite of 84 observation sites
ChinaCompositeof 84 sites
1985 - 2015
Schwarz et al. 2020 Nature Geoscience
1965-2015
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Conclusions• Combination of space-born and surface-based radiation measurements
enables to assess the distribution and changes in radiative energy flowsin the climate system.
• Allows quantification of energy balance components both under all skiesand clear skies > estimation of cloud effects
• Estimates used for model validation: latest climate model generation(CMIP6) generally in good agreement with reference estimates in multimodel mean, but still large discrepancies between individual models
• Collocated surface and TOA records allow to track changes in thepartitioning of radiative energy in the climate system: eg. recent recoveryof surface solar radiation in China is due to a less absorbing atmosphere
• A long term commitment in monitoring radiative fluxes from both spaceand surface is essential to capture changes in the energy flows in theclimate system > WE COUNT ON LIBERA!
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Conclusions• Combination of space-born and surface-based radiation measurements
enables to assess the distribution and changes in radiative energy flowsin the climate system, both under all sky and clear sky
• Estimates used for model validation: latest climate model generation(CMIP6) generally in good agreement with reference estimates in multimodel mean, but still large discrepancies between individual models
• Collocated surface and TOA records allow to track changes in thepartitioning of radiative energy in the climate system: e.g. recent recoveryof surface solar radiation in China is due to a less absorbing atmosphere
• A long term commitment in monitoring radiative fluxes from both spaceand surface is essential to capture changes in the energy flows in theclimate system > WE COUNT ON LIBERA!