Historical and Future Changes of Tropical Rain Belts: Cloud and - - PowerPoint PPT Presentation

Historical and Future Changes of Tropical Rain Belts: Cloud and Aerosol Processes

WCRP Grand Challenge 2nd Meeting on Monsoons and Tropical Rain Belts July 2-5, Trieste, Italy

Hui Su Chengxing Zhai1, Jonathan H. Jiang1, Longtao Wu1,

• J. David Neelin2, Yuk L. Yung3

1Jet Propulsion Laboratory, California Institute of Technology 2University of California, Los Angeles 3California Institute of Technology

Ou Outline

• Atmospheric energy constraint on global-mean precipitation
• Moist static energy (MSE) framework for tropical circulation
• Observations of tropical rain belt change

At Atmospheric Energy Constraint on Global-me mean Precipitation

Allen and Ingram (2002, Nature) DeAngelis et al. (2015, Nature)

Cl Clear-sk sky Longwave Radiation

Allan (2009, J. Clim)

LWc here is clear-sky longwave radiative cooling

In Inter-mo model Spread in Clear-sk sky Shortwave Abso sorption

DeAngelis et al. (2015, Nature)

Pendergrass and Hartmann (2012, GRL)

Ch Changes of Hadley Ci Circulation, Cl Cloud Radiative Effects and Pre Precipitation

∆ = 2074-2098 in “RCP4.5” – 1980-2004 in “historical run” Multi-model-mean from 15 CMIP5 coupled models “The Wet Get Wetter, The Dry Get Drier” (Su et al., 2014, JGR)

Tighteni ning ng of Tropi pical Asce cent and nd High h Cl Clouds uds Key to Preci cipi pitation n Cha Chang nge in n a Warm rmer r Cl Climate

Su et al. (2017, Nature Comm.)

Narrowing

• f ITCZ

Tightening of Hadley ascent

Expansion

• f dry and

clear area

Decrease of tropical high clouds Enhanced atmospheric longwave cooling

Reduced cloud warming effect

Intensification

• f hydrological

cycle

IT ITCZ Narrowing Linked to High Cloud Reduction

a BCC_csm1.1 b BCC_csm1.1m c CCCMA_canam4 d CNRM_cm5 e CSIRO_access1.0 f CSIRO_access1.3 g CSIRO_mk3.6 h GFDL_cm3 i GFDL_esm2g j GISS_e2r k INM_cm4 l IPSL_cm5a-lr m IPSL_cm5a-mr n IPSL_cm5b-lr

• MIROC_esm

p MIROC_miroc5 q MPI_esm-lr r MPI_esm-mr s MRI_cgcm3 t NCAR_cam5 u NCAR_ccsm4 v NCC_noresm1-m w MOHC_hadgem2-a

(a)

• 4
• 3
• 2
• 1

1 Interannual tropical dFω/dTs (%/K)

• 2
• 1

1 Interannual tropical dCF/dTs(%/K)

a b c d e f g h j k l m n

• p

q r s t u v w correlation = 0.51

(b)

• 1.0
• 0.5

0.0 0.5 Centennial tropical dFω/dTs (%/K)

• 2.0
• 1.5
• 1.0
• 0.5

0.0 0.5 1.0 1.5 Centennial tropical dCF/dTs (%/K)

a b c e f g h i j l m n

• p

q r s t u v w correlation = 0.65

Su et al. (2017, Nature Comm.)

Interannual Centennial

Lo Longwave Effect of High Cloud Reduction

a BCC_csm1.1 b BCC_csm1.1m c CCCMA_canam4 d CNRM_cm5 e CSIRO_access1.0 f CSIRO_access1.3 g CSIRO_mk3.6 h GFDL_cm3 i GFDL_esm2g j GISS_e2r k INM_cm4 l IPSL_cm5a-lr m IPSL_cm5a-mr n IPSL_cm5b-lr

• MIROC_esm

p MIROC_miroc5 q MPI_esm-lr r MPI_esm-mr s MRI_cgcm3 t NCAR_cam5 u NCAR_ccsm4 v NCC_noresm1-m w UKMO_hadgem2-a

(a)

• 2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0

0.0 Interannual tropical dCF/dTs (%/K) 1 2 3 4 5 Interannual tropical dOLR/dTs (W/m2/K)

a b c d e f g h j k l m n

• p q

r t u v w

correlation = −0.77

T+A Aqua Terra ISCCP

CERES

(b)

• 1.0
• 0.5

0.0 0.5 1.0 Centennial tropical dCF/dTs (%/K)

• 2
• 1

1 2 3 4 Centennial tropical dOLR/dTs (W/m2/K)

a b c e f g h i j l m n

• p

qr s t u v w

correlation = −0.71

Interannual Centennial

Su et al. (2017, Nature Comm.)

Ob Observational Constraint on Hydrological Sensitivity

• Observation-based Interannual dP/dTs : 2.1%/K to 3.0%/K
• Observation-constrained hydrological sensitivity: 2.6%/K to 2.9%/K
• The multi-model-mean of the 21 models is 2.6%/K

a BCC_csm1.1 b BCC_csm1.1m c CCCMA_canam4 d CNRM_cm5 e CSIRO_access1.0 f CSIRO_access1.3 g CSIRO_mk3.6 h GFDL_cm3 i GFDL_esm2g j GISS_e2r k INM_cm4 l IPSL_cm5a-lr m IPSL_cm5a-mr n IPSL_cm5b-lr

• MIROC_esm

p MIROC_miroc5 q MPI_esm-lr r MPI_esm-mr s MRI_cgcm3 t NCAR_cam5 u NCAR_ccsm4 v NCC_noresm1-m w UKMO_hadgem2-a

(a)

2 4 6 Interannual tropical dOLR/dTs (W/m2/K) 1 2 3 Interannual global LvdP/dTs (W/m2/K)

a b c d e f g h j k l m n

• p

q r s t u v w

correlation = 0.68 2 4 6 1 2 3

(b)

1 2 3 Interannual global LvdP/dTs (W/m2/K) 1.5 2.0 2.5 3.0 Temperature mediated global LvdP/dTs (W/m2/K)

a b c d e fh j k l m n

• p

q r s t u v w

correlation = 0.64

OBS.

1 2 3 1.5 2.0 2.5 3.0

Su et al. (2017, Nature Comm.)

Mo Moisture Static Energy Budget

!" # + % ⋅ '# + (!)* =

, )- (/ + 0 + 1)

!" 3 + % ⋅ '3 + (!)3 = − 5 67 (/ − 8) 9 = : − ;< = % ⋅ '> − ;< = ?@;> ∆/BCD≈ − 67 5 ∆(!)3 ∆/"FGHI≈ − 67 5 (!)∆3

∆/

BCD∝ ∆(

Xie et al. (2015, Nature. Clim. Change)

Mo Moisture Static Energy Budget

!"#$ = & + ( + ) = ( +$

↓ − +$ ↑ − /$ ↑) + (+1 ↑ − +1 ↓ + /1 ↑ − /1 ↓ ) + ( + )

∆34 ∝ ∆!

"#$

6$ 7 + 8 + 9 ⋅ ; 7 + 8 + 36<ℎ = > ?@ !"#$

AB ≈

D EF GHIJ/GM

GMS

OP+ = ⟨Ω1 −6<ℎ ⟩ 3(U, W, ?, X) = −Ω1(?) 34 Y = F + Z + [ = \ + [

Ra Radiative Changes of Clouds and Water Vapor

Voigt and Shaw (2015, Nature Geo.)

0.5 1 1.5 2 2.5 3 3.5 ' B C C _ c s m 1

• 1

' ' B C C _ c s m 1

• 1
• m

' ' B N U _ e s m ' ' C C C M A _ c a n e s m 2 ' ' C M C C _ c m ' ' C N R M _ c m 5 ' ' C S I R O _ a c c e s s 1 . ' ' C S I R O _ a c c e s s 1 . 3 ' ' C S I R O _ m k 3 . 6 ' ' G F D L _ c m 3 ' ' G I S S _ e 2

• r

' ' I P S L _ c m 5 a

• l

r ' ' I P S L _ c m 5 a

• m

r ' ' I P S L _ c m 5 b

• l

r ' ' M I R O C _ e s m ' ' M I R O C _ m i r

• c

5 ' ' M P I _ e s m

• l

r ' ' M P I _ e s m

• m

r ' ' N C A R _ c a m 5 ' ' N C A R _ c c s m 4 ' ' N C C _ n

• r

e s m ' ' U K M O _ h a d g e m 2

• e

s '

Global-Mean Precipitation Change per degree of Surface Warming (%/K) AMIP Historical RCP4.5

1 2 3 4 5 6 7 8 9 'BCC_csm1-1' 'BCC_csm1-1-m' 'BNU_esm' 'CCCMA_canesm2' 'CMCC_cm' 'CNRM_cm5' 'CSIRO_access1.0' 'CSIRO_access1.3' 'CSIRO_mk3.6' 'GFDL_cm3' 'GISS_e2-r' 'IPSL_cm5a-lr' 'IPSL_cm5a-mr' 'IPSL_cm5b-lr' 'MIROC_esm' 'MIROC_miroc5' 'MPI_esm-lr' 'MPI_esm-mr' 'NCAR_cam5' 'NCAR_ccsm4' 'NCC_noresm' 'UKMO_hadgem2-es'

ITCZ Precipitation Change per degree of Surface Warming (%/K) AMIP Historical RCP4.5

In Inter-mo model Spread of Circulation and Precipitation Changes

• 6
• 4
• 2

2 4 6 8 (1/Wup) dWup /dTs (%K−1) 0.0 0.8 1.6 2.4 3.2 4.0 4.8 5.6 6.4 7.2 8.0 (1/Pup) dPup /dTs (%K−1)

R = 0.78

AMIP Historical RCP4.5

∆" ∝ ∆$%

En Energetic c Constraint of Tropical Circu culation Change

• 10
• 5

5 10 15 20 25 (1/Fnet) dFnet /dTs (%K−1)

• 6.0
• 4.6
• 3.2
• 1.8
• 0.4

1.0 2.4 3.8 5.2 6.6 8.0 (1/Wup) dWup /dTs (%K−1)

R = 0.74

AMIP Historical RCP4.5

∆"# ∝ ∆%

&'(

Lo Longwave Cloud Radiative Effect

• 10
• 5

5 (1/Fnet) dOLRTOA

cld /dTs (%K−1)

• 6.0
• 4.6
• 3.2
• 1.8
• 0.4

1.0 2.4 3.8 5.2 6.6 8.0 (1/Wup) dWup /dTs (%K−1)

R = −0.52

AMIP Historical RCP4.5

• Less longwave loss at TOA leads to a stronger ascent

Cl Clear-sk sky Shortwave Abso sorption

2 4 6 8 10 12 14 (1/Fnet) dFSW

clr /dTs (%K−1)

• 6.0
• 4.6
• 3.2
• 1.8
• 0.4

1.0 2.4 3.8 5.2 6.6 8.0 (1/Wup) dWup /dTs (%K−1)

R = 0.43

AMIP Historical RCP4.5

• Greater clear-sky shortwave absorption leads to a stronger ascent

Th The Role of Absorbing Aerosols

0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.007 dABSaero/dTs (%K−1) 3 4 5 6 7 8 9 10 11 12 13 14 15 (1/Fnet) dFSW

clr /dTs (%K−1)

R = 0.51

Historical

Ob Observed Narrow

• wing of the ITCZ

Wodzicki and Rapp (2016, JGR)

Ob Observed Narrow

• wing of the ITCZ

Su et al. (2018, in prep)

CM CMIP5 Simulations of the Narrowing

Su et al. (2018, in prep)

Su Summary

• The changes of the ITCZ intensity and area are strongly

constrained by atmospheric energy budget.

• Model diversity in the radiative effects of tropical high

clouds and absorbing aerosols contributes significantly to the inter-model spread in the ITCZ intensity and area changes in the past decades.

• Observational evidence of the narrowing of ITCZ is robust.