On dynamic and thermodynamic components of cloud changes

Bony, Sandrine; Dufresne, Jean‐Louis; Treut, Hervé Le; Morcrette, Jean‐Jacques; Senior, C. A.

doi:10.1007/s00382-003-0369-6

Cited by 410 publications

(487 citation statements)

References 56 publications

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“…8a), and is less clearly related to a change in the meridional moisture transport. This can be related to changes in the PDF (Probability Density Function) of the 500 hPa large-scale vertical velocity, x 500 , that characterizes the large-scale tropical circulation (Bony et al 2004). The change in tropical dynamics is particularly clear when increasing the resolution in longitude from 96 9 95 to 144 9 95 (full blue curve in Fig.…”

Section: Energy Budget In the Imposed-sst Simulationsmentioning

confidence: 99%

Impact of the LMDZ atmospheric grid configuration on the climate and sensitivity of the IPSL-CM5A coupled model

et al. 2012

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The IPSL-CM5A climate model was used to perform a large number of control, historical and climate change simulations in the frame of CMIP5. The refined horizontal and vertical grid of the atmospheric component, LMDZ, constitutes a major difference compared to the previous IPSL-CM4 version used for CMIP3. From imposed-SST (Sea Surface Temperature) and coupled numerical experiments, we systematically analyze the impact of the horizontal and vertical grid resolution on the simulated climate. The refinement of the horizontal grid results in a systematic reduction of major biases in the mean tropospheric structures and SST. The mid-latitude jets, located too close to the equator with the coarsest grids, move poleward. This robust feature, is accompanied by a drying at mid-latitudes and a reduction of cold biases in mid-latitudes relative to the equator. The model was also extended to the stratosphere by increasing the number of layers on the vertical from 19 to 39 (15 in the stratosphere) and adding relevant parameterizations. The 39-layer version captures the dominant modes of the stratospheric variability and exhibits stratospheric sudden warmings. Changing either the vertical or horizontal resolution modifies the global energy balance in imposed-SST simulations by typically several W/m 2 which translates in the coupled atmosphere-ocean simulations into a different global-mean SST. The sensitivity is of about 1.2 K per 1 W/m 2 when varying the horizontal grid. A re-tuning of model parameters was thus required to restore this energy balance in the imposed-SST simulations and reduce the biases in the simulated mean surface temperature and, to some extent, latitudinal SST variations in the coupled experiments for the modern climate. The tuning hardly compensates, however, for robust biases of the coupled model. Despite the wide range of grid configurations explored and their significant impact on the present-day climate, the climate sensitivity remains essentially unchanged.

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Section: Energy Budget In the Imposed-sst Simulationsmentioning

confidence: 99%

Impact of the LMDZ atmospheric grid configuration on the climate and sensitivity of the IPSL-CM5A coupled model

et al. 2012

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“…Other work has sorted variables in ways other than by geography: one such example is that of Bony et al (2004), which uses a framework based on the large-scale atmospheric circulation to define a series of dynamical regimes responding to different values of vertical velocity (ω). In addition, mass flux traditionally has been examined on pressure levels, but also within dry (Held and Schneider, 1999) and moist isentropic layers (Pauluis et al, 2008), in an attempt to capture a more Lagrangian description of the circulation.…”

Section: Framework Of Analysismentioning

confidence: 99%

Deconstructing the Hadley cell heat transport

Heaviside

Czaja

2012

Quart J Royal Meteoro Soc

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The mechanisms responsible for poleward atmospheric heat transport at low latitudes are examined in the European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) dataset. Deep meridional overturning circulations are found in regions experiencing frequent convection (i.e. the Indo-Pacific 'warm pool') and it is suggested that these are the primary reason why atmospheric heat transport seems dominated by axisymmetric motions or 'Hadley cell heat transport'. In contrast, the more complex distribution of meridional mass transport by the circulations over the 'cold tongue' regions (such as the eastern Atlantic area) and the presence of a pronounced minimum in moist static energy at mid-levels constrain these regions to contribute little to poleward heat transport year round. Regions experiencing frequent convection do not, however, account for all the annual mean poleward atmospheric heat transport. At the Equator, an annual net southward transport of heat of about 0.4 PW (1 PW = 10 15 W) is found, but the deep overturning cells found in the most convectively active regions contribute only 25% of this. This small contribution of ∼0.1 PW is understood to reflect a seasonal cancellation between large (∼1 PW) northward and southward heat transports in boreal winter and summer respectively. During December-February, most of the cross-equatorial heat transport is attributable to the convective regions, whereas in June-August, only half is attributable to these regions. In this season, there is a significant amount of heat transport by the strong Somali jet associated with the Asian summer monsoon. Rather than attributing the net southward crossequatorial heat transport to asymmetries in the climatology associated with the northerly position of the intertropical convection zones throughout the year over the eastern Pacific and Atlantic oceans, our diagnostics suggest that the Somali jet is a significant contributor to the annual net southward atmospheric heat transport at the Equator.

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“…The impact of low-cloud cover on the radiation budget of Earth has been the source of active research for decades (e.g., Bony et al, 2004;Bony & Dufresne, 2005;Klein & Hartmann, 1993;Randall et al, 1984). Recently, Qu et al (2014Qu et al ( , 2015 provided a thorough examination of the dependencies between low-cloud cover, the estimated inversion strength (EIS), and surface temperature in both observations, and an ensemble of models from CMIP3 and CMIP5.…”

Section: Introductionmentioning

confidence: 99%

The Diversity of Cloud Responses to Twentieth Century Sea Surface Temperatures

Silvers

Paynter

Zhao

2018

Geophysical Research Letters

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Low‐level clouds are shown to be the conduit between the observed sea surface temperatures (SST) and large decadal fluctuations of the top of the atmosphere radiative imbalance. The influence of low‐level clouds on the climate feedback is shown for global mean time series as well as particular geographic regions. The changes of clouds are found to be important for a midcentury period of high sensitivity and a late century period of low sensitivity. These conclusions are drawn from analysis of amip‐piForcing simulations using three atmospheric general circulation models (AM2.1, AM3, and AM4.0). All three models confirm the importance of the relationship between the global climate sensitivity and the eastern Pacific trends of SST and low‐level clouds. However, this work argues that the variability of the climate feedback parameter is not driven by stratocumulus‐dominated regions in the eastern ocean basins, but rather by the cloudy response in the rest of the tropics.

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On dynamic and thermodynamic components of cloud changes

Cited by 410 publications

References 56 publications

Impact of the LMDZ atmospheric grid configuration on the climate and sensitivity of the IPSL-CM5A coupled model

Impact of the LMDZ atmospheric grid configuration on the climate and sensitivity of the IPSL-CM5A coupled model

Deconstructing the Hadley cell heat transport

The Diversity of Cloud Responses to Twentieth Century Sea Surface Temperatures

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