Total cloud cover from satellite observations and climate models

Probst, P. A.; Rizzi, Rolando; Tosi, E.; Lucarini, Valerio; Maestri, Tiziano

doi:10.1016/j.atmosres.2012.01.005

Cited by 30 publications

(20 citation statements)

References 35 publications

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“…Significant regional differences are evident in the model cloud fractions, a known issue for global general circulation models documented in the literature (e.g. Pincus et al, 2008;Probst et al, 2012). Two models have cloud fractions (GOCART-GEOS4: 0.49 and LMDZ: 0.48) at the lower end of the observed range (Marchand et al, 2010) (although this quantity is generally not consistently defined between models and detection limited observations).…”

Section: Host Model Componentsmentioning

confidence: 94%

Host model uncertainties in aerosol radiative forcing estimates: results from the AeroCom Prescribed intercomparison study

et al. 2013

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Simulated multi-model "diversity" in aerosol direct radiative forcing estimates is often perceived as a measure of aerosol uncertainty. However, current models used for aerosol radiative forcing calculations vary considerably in model components relevant for forcing calculations and the associated "host-model uncertainties" are generally convoluted with the actual aerosol uncertainty. In this AeroCom Prescribed intercomparison study we systematically isolate and quantify host model uncertainties on aerosol forcing experiments through prescription of identical aerosol radiative properties in twelve participating models.

Even with prescribed aerosol radiative properties, simulated clear-sky and all-sky aerosol radiative forcings show significant diversity. For a purely scattering case with globally constant optical depth of 0.2, the global-mean all-sky top-of-atmosphere radiative forcing is −4.47 Wm⁻² and the inter-model standard deviation is 0.55 Wm⁻², corresponding to a relative standard deviation of 12%. For a case with partially absorbing aerosol with an aerosol optical depth of 0.2 and single scattering albedo of 0.8, the forcing changes to 1.04 Wm⁻², and the standard deviation increases to 1.01 W⁻², corresponding to a significant relative standard deviation of 97%. However, the top-of-atmosphere forcing variability owing to absorption (subtracting the scattering case from the case with scattering and absorption) is low, with absolute (relative) standard deviations of 0.45 Wm⁻² (8%) clear-sky and 0.62 Wm⁻² (11%) all-sky.

Scaling the forcing standard deviation for a purely scattering case to match the sulfate radiative forcing in the AeroCom Direct Effect experiment demonstrates that host model uncertainties could explain about 36% of the overall sulfate forcing diversity of 0.11 Wm⁻² in the AeroCom Direct Radiative Effect experiment.

Host model errors in aerosol radiative forcing are largest in regions of uncertain host model components, such as stratocumulus cloud decks or areas with poorly constrained surface albedos, such as sea ice. Our results demonstrate that host model uncertainties are an important component of aerosol forcing uncertainty that require further attention

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Section: Host Model Componentsmentioning

confidence: 94%

Host model uncertainties in aerosol radiative forcing estimates: results from the AeroCom Prescribed intercomparison study

et al. 2013

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“…Moreover, Hogan et al (2009) found that models tend to be least skillful at predicting the timing and placement of boundary-layer clouds and most skillful at predicting mid-level clouds. Recently, Probst et al (2012) compared global and zonal cloud cover fraction for total cloudiness from the ISCCP D2 dataset to the same quantities produced by 21 climate models, and found that most models underestimate the yearly averaged values of cloudiness over all the analyzed areas.…”

Section: Polarization (Caliop) Aboard Calipso (Cloud-aerosol Lidar Anmentioning

confidence: 99%

Behavior of cloud base height from ceilometer measurements

Costa-Surós

Calbó

González

et al. 2013

Atmospheric Research

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“…A recently published paper by Probst et al (2012) shows that the global mean cloud fraction (CF) in the CMIP3 models, averaged from January 1984 to December 1999, exhibits a considerable variance and generally underestimates the CF as given by the International Satellite Cloud Climatology Project (ISCCP) D2 data set in a latitudinal belt from 60 • S to 60 • N (see Fig. 1 in Probst et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Cloud radiative forcing intercomparison between fully coupled CMIP5 models and CERES satellite data

et al. 2014

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Abstract. In this paper, radiative fluxes for 10 years from 11 models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) and from CERES satellite observations have been analyzed and compared. Under presentday conditions, the majority of the investigated CMIP5 models show a tendency towards a too-negative global mean net cloud radiative forcing (NetCRF) as compared to CERES. A separate inspection of the long-wave and shortwave contribution (LWCRF and SWCRF) as well as cloud cover points to different shortcomings in different models. Models with a similar NetCRF still differ in their SWCRF and LWCRF and/or cloud cover. Zonal means mostly show excessive SWCRF (too much cooling) in the tropics between 20 • S and 20 • N and in the midlatitudes between 40 to 60 • S. Most of the models show a too-small/too-weak LWCRF (too little warming) in the subtropics (20 to 40 • S and N). Difference maps between CERES and the models identify the tropical Pacific Ocean as an area of major discrepancies in both SWCRF and LWCRF. The summer hemisphere is found to pose a bigger challenge for the SWCRF than the winter hemisphere. The results suggest error compensation to occur between LWCRF and SWCRF, but also when taking zonal and/or annual means. Uncertainties in the cloud radiative forcing are thus still present in current models used in CMIP5.

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Total cloud cover from satellite observations and climate models

Cited by 30 publications

References 35 publications

Host model uncertainties in aerosol radiative forcing estimates: results from the AeroCom Prescribed intercomparison study

Host model uncertainties in aerosol radiative forcing estimates: results from the AeroCom Prescribed intercomparison study

Behavior of cloud base height from ceilometer measurements

Cloud radiative forcing intercomparison between fully coupled CMIP5 models and CERES satellite data

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