Cited by 375Atmospheric aerosols and cloudsClimate variability and modelsMeteorological Phenomena and Simulations

The ‘too few, too bright’ tropical low-cloud problem in CMIP5 models.

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Nam, C., Bony, S., Dufresne, J.‐L., Chepfer, H.·2012·Geophysical Research Letters

Abstract

Previous generations of climate models have been shown to under‐estimate the occurrence of tropical low‐level clouds and to over‐estimate their radiative effects. This study analyzes outputs from multiple climate models participating in the Fifth phase of the Coupled Model Intercomparison Project (CMIP5) using the Cloud Feedback Model Intercomparison Project Observations Simulator Package (COSP), and compares them with different satellite data sets. Those include CALIPSO lidar observations, PARASOL mono‐directional reflectances and CERES radiative fluxes at the top of the atmosphere. We show that current state‐of‐the‐art climate models predict overly bright low‐clouds, even for a correct low‐cloud cover. The impact of these biases on the Earth' radiation budget, however, is reduced by compensating errors. Those include the tendency of models to under‐estimate the low‐cloud cover and to over‐estimate the occurrence of mid‐ and high‐clouds above low‐clouds. Finally, we show that models poorly represent the dependence of the vertical structure of low‐clouds on large‐scale environmental conditions. The implications of this ‘too few, too bright low‐cloud problem’ for climate sensitivity and model development are discussed.

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Crossref · 10.1029/2012gl053421

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  • Even when the CMIP surface radiative forcing is correct, the cloud cover is still typically too low, likely due to an underestimation of optically thin stratiform clouds.

    “Even when the CMIP surface radiative forcing is correct, the cloud cover is still typically too low (de Szoeke et al., 2012), likely due to an underestimation of optically thin stratiform clouds (Nam et al., 2012;Zuidema et al., 2012;Delgadillo et al., 2018;Wood et al., 2018).”

    From The tropical atlantic observing system (2019) · cites this paper as Nam et al., 2012

    The Conclusion and Discussion (§6, paragraph 20; page unavailable) reports that CMIP5 models underestimate tropical low-cloud cover and overestimate low-cloud optical thickness. It does not identify an underestimation of optically thin stratiform clouds as the likely cause. The preceding statement about surface radiative forcing is cited to a different source, not Nam et al. (LLM, conf=0.84)

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Research works printed but not linked: 1

  1. Jam, A., F. Hourdin, C. Rio, and F. Couvreux (2012), Resolved versus param- etrized boundary-layer plumes. Part III: A diagnostic boundary-layer cloud parameterization derived from large eddy simulations, Boundary Layer Meteorol., in press.

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Authors
Nam, C., Bony, S., Dufresne, J. ‐., & Chepfer, H.
Affiliations
Centre National de la Recherche Scientifique (FR)
Corresponding author
Nam, C.
Venue
Geophysical Research Letters
Published
2012-11
Volume
39
Issue
21
Pages
L21801
ISSN
  • 0094-8276 (ISSN-L)
  • 1944-8007
OpenAlex
W1925502865
Cited by
375
References
35
Citations by year
2026: 10 · 2025: 22 · 2024: 26 · 2023: 38 · 2022: 33 · 2021: 41 · 2020: 38 · 2019: 27 · 2018: 32 · 2017: 31 · 2016: 26 · 2015: 29 · 2014: 15 · 2013: 6
FWCI
13.30
Type
journal article
Language
en
Open access
Locations
  • Geophysical Research Letters (publishedVersion)
  • HAL (submittedVersion, other-oa)
Funders
European Commission
Topics
  • Physical Sciences › Environmental Science › Global and Planetary Change › Atmospheric aerosols and clouds
  • Physical Sciences › Environmental Science › Global and Planetary Change › Climate variability and models
  • Physical Sciences › Earth and Planetary Sciences › Atmospheric Science › Meteorological Phenomena and Simulations
Keywords
cloud radiative effects, cloud vertical structure, cloud feedback, Earth radiation budget, cloud model evaluation, CALIPSO lidar, climate sensitivity, CMIP5

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