hemispheric asymmetry of tropical expansion under co2 forc

manuscript submitted to Geophysical Research Letters

Supporting Information for“Hemispheric asymmetry of tropical expansion under CO2 forc-ing”

O. Watt-Meyer1, D. M. W. Frierson1, and Q. Fu1

1Department of Atmospheric Sciences, University of Washington

Contents

1. Table S1

2. Figure S1

3. Figure S2

4. Figure S3

5. Figure S4

6. Figure S5

Table S1. Models from which output is used in this study. The second column shows the mod-

els that performed the piControl, abrupt4xCO2 and 1pctCO2 experiments. The third column

shows the models that performed the amip, amip4xCO2, amip4K and amipFuture experiments.

piControl, 1pctCO2, amip, amip4xCO2,abrupt4xCO2 amip4K, amipFuture

Modeling center Model name Model name

CSIRO-BOM ACCESS1-0 -CCCMA CanESM2 CanAM4NCAR CCSM4 -

CNRM-CERFACS CNRM-CM5-2 CNRM-CM5CSIRO-QCCCE CSIRO-Mk3-6-0 -CSIRO-QCCCE CSIRO-Mk3L-1-2 -NASA-GISS GISS-E2-H -

MOHC HadGEM2-ES HadGEM2-AINM inmcm4 -IPSL IPSL-CM5A-LR IPSL-CM5A-LRIPSL - IPSL-CM5B-LRIPSL IPSL-CM5A-MR -

MIROC MIROC5 MIROC5MPI-M - MPI-ESM-LRMPI-M MPI-ESM-MR MPI-ESM-MRMPI-M MPI-ESM-P -MRI MRI-CGCM3 MRI-CGCM3NCC NorESM1-M -

# of models 16 9

Corresponding author: O. Watt-Meyer, [email protected]

–1–


SH/NHAnnual

SH/NHDJF

SH/NHMAM

SH/NHJJA

SH/NHSON

−5.0

−2.5

0.0

2.5

Poleward

shift[∘]

a) Ψ500

SH/NHAnnual

SH/NHDJF

SH/NHMAM

SH/NHJJA

SH/NHSON

−5.0

−2.5

0.0

2.5

b) ∫Ψdp

SH/NHAnnual

SH/NHDJF

SH/NHMAM

SH/NHJJA

SH/NHSON

−2

0

2

4

Poleward

shift[∘]

c) Usfc

SH/NHAnnual

SH/NHDJF

SH/NHMAM

SH/NHJJA

SH/NHSON

−10

−5

0

5d) P-E=0

Hadley cell expansion in each hemisphere, abrupt4xCO2 - piControl

Figure S1. Box plots of the difference in various circulation diagnostics between the

abrupt4xCO2 experiment (averaged over years 100 to 150) and the piControl experiment.

Data are shown for the annual mean and each season separately, as well as for the Southern

Hemisphere (SH) and Northern Hemisphere (NH) separately. The four diagnostics are (a) zero-

crossing of the 500 hPa mass streamfunction, (b) zero-crossing of the vertically integarated mass

streamfunction, (c) zero-crossing of the zonal-mean surface zonal wind and (d) zero-crossing of

zonally averaged precipitation minus evaporation. Horizontal orange lines are median, boxes

shows the interquartile spread and whiskers show the full range of data except outliers, which are

marked by the individual circles.

–2–


Annual DJF MAM JJA SON

−2

0

2

4

6

8SHminusNHshift[∘]

a) Ψ500


−2

0

2

4

6

8b) ∫Ψdp


−2

0

2

4

6

8

SHminusNHshift[∘]

c) Usfc


−2

0

2

4

6

8d) P-E=0

Asymmetry of Hadley cell expansion, abrupt4xCO2 - piControl

Figure S2. As in Fig. S1, but for the difference between the response in the Southern Hemi-

sphere and in the Northern Hemisphere. Positive numbers imply a greater expansion in the

Southern Hemisphere than in the Northern Hemisphere.

Figure S3. Difference in surface temperature between years 100 to 150 of the abrupt4xCO2

experiment and the piControl experiment, averaged across the sixteen models listed in the second

column of Table S1.

–3–


Figure S4. Difference in surface temperature between amip4K and amip experiments, aver-

aged across the nine models listed in the third column on Table S1. c2

Figure S5. Difference in surface temperature between amipFuture and amip experiments,

averaged across the nine models listed in the third column of Table S1. c4

–4–

hemispheric asymmetry of tropical expansion under co2 forc

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