Supporting Information
Bony et al. 10.1073/pnas.1601472113
Fig. S1. Monthly precipitation (normalized by its global mean value) predicted by the IPSL and NCAR GCMs in RCE simulations forced by an SST of 295 K or 305 K.
Top four panels: with cloud-radiative effects. Bottom four panels: without cloud-radiative effects. In the absence of cloud-radiative effects, these GCMs do not predict
any large-scale convective aggregation.
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A
0
0
280
285
290
295
300
305
310
100
100
200
Pressure [hPa]
200
Pressure [hPa]
280
285
290
295
300
305
310
300
300
400
400
500
500
600
600
0.0
0.1
0.2
0.0
Cloud fraction
0.2
0.4
0.6
0.8
Divergence [day^−1]
B
0.15
0.10
0.20
0.15
280
285
290
295
300
305
310
0.15
Stability [K/hPa]
280
285
290
295
300
305
310
Anvil cloud fraction
Anvil cloud fraction
0.20
0.10
280
285
290
295
300
305
0.1
310
0.10
0.05
0.00
0.05
0.05
280
285
290
295
300
305
310
0.3
0.5
0.7
280
0.9
285
290
295
300
305
310
Sea Surface Temperature [K]
Radiatively−driven divergence [day^−1]
Sea Surface Temperature [K]
Fig. S2. CRM simulations: vertical profiles of (Upper Left) cloud fraction and (Upper Right) radiatively driven divergence associated with different SSTs (ranging from
280 K to 310 K), and relationship (Bottom Left) between the anvil cloud amount and SST, (Bottom Center) between the anvil cloud amount and the radiatively driven
divergence, and (Bottom Right) between the static stability at the level of maximum divergence (and along the 220 K isotherm, dashed line) and SST derived from
nonrotating RCE CRM simulations from Wing and Cronin (21). All quantities are domain averages computed over days 50–75 of each simulation.
ipsl (AMIP)
mpi (AMIP)
0.17
0.165
0.16
0.235
Anvil cloud fraction
0.19
Anvil cloud fraction
Anvil cloud fraction
0.175
ncar (AMIP)
0.185
0.18
0.175
298
298.2 298.4 298.6 298.8
299
Surface temperature [K]
0.23
0.225
0.22
298.6 298.8
299
299.2 299.4 299.6
Surface temperature [K]
297
297.2 297.4 297.6 297.8
298
Surface temperature [K]
Fig. S3. Interannual variations in full-blown GCMs: relationship between the tropical mean anvil cloud amount and the tropical surface temperature (land + ocean)
derived from (Left) IPSL, (Center) MPI, and (Right) NCAR GCMs in AMIP simulations run in a realistic configuration (with rotation, continents, etc.) and forced by
observed sea surface temperatures and time-varying radiative forcings (greenhouse gases and aerosols). Each point represents an annual average of tropical
mean quantities (30°S–30°N) during 1979–2005.
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Fig. S4. Relationships among anvil cloud fraction, Tsfc , Dr , and S. Relationships are plotted at the height of anvil clouds, derived from an AMIP simulation run
with the IPSL-CM5A-LR GCM in the absence of convective parameterization [so-called SPOOKIE simulation (43)]. Each point represents an annual average of
tropical mean quantities (30°S–30°N) during 1979–2005.
0.45
ipsl
ncar
Anvil cloud fraction
Anvil cloud fraction
0.45
0.35
0.25
0.15
ipsl
ncar
0.35
0.25
0.15
0.05
0.25
0.45
0.65
0.05
0.85
0.15
ipsl
ncar
Static Stability [K/hPa]
Static Stability [K/hPa]
0.15
0.25
0.45
0.65
0.85
Radiatively−driven divergence [day^−1]
Radiatively−driven divergence [day^−1]
0.10
0.05
0.00
ipsl
ncar
0.10
0.05
0.00
285
290
295
300
Sea Surface Temperature [K]
305
310
285
290
295
300
305
310
Sea Surface Temperature [K]
Fig. S5. Clouds-on vs. clouds-off: comparison of the relationship (Top) between the anvil cloud amount and the radiatively driven divergence and (Bottom)
between the static stability at the level of maximum divergence and SST in IPSL and NCAR GCM simulations run (Left) with and (Right) without cloud-radiative
effects. (Top Left) R2 = 0.68, ∂f =∂Dr = 0.40 ± 0.13 d; (Top Right) R2 = 0.65, ∂f =∂Dr = 0.37 ± 0.14 d.
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IPSL GCM
1.0
CRE and ozone
CRE and no ozone
no CRE and no ozone
aggregation index
0.9
0.8
0.7
0.6
0.5
0.4
0.3
290
295
300
305
Sea surface temperature [K]
CRE and ozone
CRE and no ozone
0.25
291
293
295
297
299
301
303
305
307
0.20
0.15
0.10
0.1
0.2
0.3
0.4
0.5
0.6
Radiatively−driven divergence [day^−1]
Anvil cloud fraction
0.25
0.65
Anvil cloud fraction
0.30
Anvil cloud fraction
0.30
no CRE and no ozone
0.60
291
293
295
297
299
301
303
305
307
0.20
0.15
0.10
0.1
0.2
0.3
0.4
0.5
0.6
Radiatively−driven divergence [day^−1]
291
293
295
297
299
301
303
305
307
0.55
0.50
0.45
0.2
0.3
0.4
0.5
0.6
0.7
Radiatively−driven divergence [day^−1]
Fig. S6. Sensitivity to ozone and cloud-radiative effects in the IPSL GCM: comparison of (Top) aggregation vs. SST and of (Middle) the relationship between
the anvil cloud amount and the radiatively driven divergence and (Bottom) between static stability at the level of maximum divergence and SST in
RCE simulations (Left) with cloud-radiative effects (CRE) and ozone, (Center) with cloud-radiative effects but without ozone, and (Right) without cloudradiative effects and without ozone. Also reported in Bottom panels are the evolutions of static stability along the 225 K isotherm. The aggregation index is
defined as the fractional area of the globe covered by large-scale subsidence (31). A value close to 0.5 corresponds to the absence of aggregation.
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0.30
295
299
301
303
306
Static Stability [K/hPa]
Anvil cloud fraction
0.25
0.15
prescribed SST
interactive SST
0.20
295
299
301
303
306
prescribed SST
interactive SST
0.10
0.05
0.15
0.00
0.10
0.1
0.2
0.3
0.4
Radiatively−driven divergence [day^−1]
0.5
294
296
298
300
302
304
306
Sea Surface Temperature [K]
Fig. S7. Prescribed vs. interactive SST: relationship between (Left) the anvil cloud fraction and the radiatively driven divergence and (Right) the static stability
at the level of maximum divergence and SST in IPSL GCM simulations forced by prescribed SSTs or by computing the SST interactively, using an ocean mixed
layer of 10 m depth and a CO2 atmospheric concentration set to 0.5, 0.75, 1, 2, or 3 times its present-day value.
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