The role of water vapor and cloud feedback on the evolution of the Indian summer monsoon

over the last 22,000 years

Chetankumar Jalihal

Guided by: Prof. J. Srinivasan &Prof. Arindam Chakraborty

jalihal@iisc.ac.in Indian Institute of Science

mailto:jalihal@iisc.ac.in

Short version

OBJECTIVE

DIFFERENT SENSITIVITY OF

MONSOON TO INSOLATION

1

TraCE21K simulation

Model: CCSM3, fully coupled ESM, with transient boundary conditions,3.75ᵒ x 3.75ᵒ

Duration: 22 Kyrs

OBJECTIVE

OBJECTIVE

Identify the feedbacks.

Quantify the role of forcings and feedbacks.

2

𝑮𝑴𝑺 = −𝑃

𝐵

𝑃𝑇𝑼.𝛁𝒎 + 𝝎

𝜕𝒎𝜕𝑝

𝑑𝑝

𝐿𝑣 𝑃𝐵

𝑃𝑇𝑼.𝛁𝒒 + 𝝎

𝜕𝒒𝜕𝑝

𝑑𝑝

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗𝑮𝑴𝑺

METHOD

ENERGETICS FRAMEWORK(Neelin & Held 1987; Raymond 2009)

3

Net energy flux into atmosphere

Gross Moist Stability

RESULTS

GMS IS A UNIQUE FUNCTION OF

WATER VAPOR

4

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗𝑮𝑴𝑺

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗

ൗ𝟖𝟎. 𝟒 𝑪𝑾𝑽 − 𝟏. 𝟑

Jalihal et al. (2019) Nat. Comm.

RESULTS

(P-E) OVER THE LAST 22,000 YRS

5

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗

ൗ𝟖𝟎. 𝟒 𝑪𝑾𝑽 − 𝟏. 𝟑

Jalihal et al. (2019) Nat. Comm.

RESULTS

QDIV DRIVES (P-E) DURING

HOLOCENE

6

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗

ൗ𝟖𝟎. 𝟒 𝑪𝑾𝑽 − 𝟏. 𝟑

CWV fixed at pre-industrial values.

Jalihal et al. (2019) Nat. Comm.

RESULTS

WATER VAPOR PLAYS CRUCIAL

ROLE DURING DEGLACIAL

7

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗

ൗ𝟖𝟎. 𝟒 𝑪𝑾𝑽 − 𝟏. 𝟑

Qdiv fixed at pre-industrial values.

Jalihal et al. (2019) Nat. Comm.

RESULTS

GREENHOUSE GASES AND ICE

SHEETS AFFECT GMS ALONE

8

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗

ൗ𝟖𝟎. 𝟒 𝑪𝑾𝑽 − 𝟏. 𝟑GHG and ice sheets do not influence Qdiv

Jalihal et al. (2019) Nat. Comm.

Qdiv

(m

m d

ay

-1)

Qdiv

(m

m d

ay

-1)

RESULTS

ORBITAL FORCING AFFECTS BOTH

GMS AND QDIV

9

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗

ൗ𝟖𝟎. 𝟒 𝑪𝑾𝑽 − 𝟏. 𝟑

Even though both Qdiv and GMS are influenced, GMS is dominant, when boundary conditions are that of LGM.

Jalihal et al. (2019) Nat. Comm.

Qdiv

(m

m d

ay

-1)

Energy available

GHG & Ice sheets

Total column water vapor

Surface temperature

Precipitation

1 2

1 - Dominant during the Deglacial

2 - Dominant during the Holocene

Insolation

Jalihal et al. (2019) Nat. Comm.

Long version

MOTIVATION

INSOLATION OVER LAST 22,000 YRS

1

HoloceneDeglacial

Summer insolation over India

MOTIVATION

THIS VARIATION IS DUE TO

PRECESSION OF EARTH

1

HoloceneDeglacial

23,000 yrs

OBJECTIVE

DIFFERENT SENSITIVITY OF

MONSOON TO INSOLATION

2

TraCE21K simulation

Model: CCSM3, fully coupled ESM, with transient boundary conditions,3.75ᵒ x 3.75ᵒ

Duration: 22 Kyrs

OBJECTIVE

DIFFERENT SENSITIVITY OF

MONSOON TO INSOLATION

2

Deglacial forcings: Insolation greenhouse gasesice sheets

Holocene forcings: Mainly insolation

OBJECTIVE

OBJECTIVE

Identify the feedbacks.

Quantify the role of forcings and feedbacks.

3

Method

4

Based on the equations for conservation of moisture & Moist Static Energy.

න

𝑃𝑡

𝑃𝑏

𝑈. 𝛻𝑚 + 𝜔𝜕𝑚

𝜕𝑝𝑑𝑝 = 𝑔[𝐹𝑏 − 𝐹𝑡]

න

𝑃𝑡

𝑃𝑏

𝑈. 𝛻𝑞 + 𝜔𝜕𝑞

𝜕𝑝𝑑𝑝 = 𝑔[𝐸 − 𝑃]

m - Moist Static Energy;

(m = Cp*T + g*Z + Lv *q)

Fb - Bottom Fluxes

Ft - Fluxes at Top of Atm.

u - x component of velocity

METHOD

ENERGETICS FRAMEWORK

q - Specific Humidity (kg/Kg)

ω - Vertical velocity (Pa/s)

Pb - Surface Pressure

Pt - Top Pressure

v - y component of velocity

5

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗𝑮𝑴𝑺

METHOD

ENERGETICS FRAMEWORK(Neelin & Held 1987; Raymond 2009)

6

𝑮𝑴𝑺 = −𝑃

𝐵

𝑃𝑇𝑼.𝛁𝒎+ 𝝎

𝜕𝒎𝜕𝑝

𝑑𝑝

𝐿𝑣 𝑃𝐵

𝑃𝑇𝑼.𝛁𝒒 + 𝝎

𝜕𝒒𝜕𝑝

𝑑𝑝

𝑮𝑴𝑺 = −𝑃

𝐵

𝑃𝑇𝑼.𝛁𝒎 + 𝝎

𝜕𝒎𝜕𝑝

𝑑𝑝

𝐿𝑣 𝑃𝐵

𝑃𝑇𝑼.𝛁𝒒 + 𝝎

𝜕𝒒𝜕𝑝

𝑑𝑝

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗𝑮𝑴𝑺

METHOD

ENERGETICS FRAMEWORK(Neelin & Held 1987; Raymond 2009)

6

Net energy flux into atmosphere (top + bottom)

Over land net surface energy fluxes are small.

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗𝑮𝑴𝑺

METHOD

ENERGETICS FRAMEWORK(Neelin & Held 1987; Raymond 2009)

6

m

ω𝑮𝑴𝑺 = −

𝑃𝐵

𝑃𝑇𝑼.𝛁𝒎 + 𝝎

𝜕𝒎𝜕𝑝

𝑑𝑝

𝐿𝑣 𝑃𝐵

𝑃𝑇𝑼.𝛁𝒒 + 𝝎

𝜕𝒒𝜕𝑝

𝑑𝑝

Gross Moist Stability.

Primarily depends on vertical profile of m and ω

𝑮𝑴𝑺 = −𝑃

𝐵

𝑃𝑇𝑼.𝛁𝒎 + 𝝎

𝜕𝒎𝜕𝑝

𝑑𝑝

𝐿𝑣 𝑃𝐵

𝑃𝑇𝑼.𝛁𝒒 + 𝝎

𝜕𝒒𝜕𝑝

𝑑𝑝

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗𝑮𝑴𝑺

METHOD

ENERGETICS FRAMEWORK(Neelin & Held 1987; Raymond 2009)

6

m

ω

Qdiv = TOA_Net_SW - TOA_OLR + SFC_RAD + SHF + LHF

TOA_Net_SW- Net Short Wave at Top of Atm

TOA_OLR - Net Outgoing Longwave Radiation

Qnet

RESULTS

A CLOSER LOOK AT QDIV

7

Qdiv over land is influenced by insolation and cloud radiative feedback.

Results

8

RESULTS

GMS IS A UNIQUE FUNCTION OF

WATER VAPOR

9

Jalihal et al. (2019) Nat. Comm.

RESULTS

GMS IS A UNIQUE FUNCTION OF

WATER VAPOR

9

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗𝑮𝑴𝑺

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗

ൗ𝟖𝟎. 𝟒 𝑪𝑾𝑽 − 𝟏. 𝟑

Jalihal et al. (2019) Nat. Comm.

RESULTS

(P-E) OVER THE LAST 22,000 YRS

10

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗

ൗ𝟖𝟎. 𝟒 𝑪𝑾𝑽 − 𝟏. 𝟑

Jalihal et al. (2019) Nat. Comm.

RESULTS

QDIV DRIVES (P-E) DURING

HOLOCENE

10

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗

ൗ𝟖𝟎. 𝟒 𝑪𝑾𝑽 − 𝟏. 𝟑

CWV fixed at pre-industrial values.

Jalihal et al. (2019) Nat. Comm.

RESULTS

WATER VAPOR PLAYS CRUCIAL

ROLE DURING DEGLACIAL

10

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗

ൗ𝟖𝟎. 𝟒 𝑪𝑾𝑽 − 𝟏. 𝟑

Qdiv fixed at pre-industrial values.

Jalihal et al. (2019) Nat. Comm.

Role of different forcings

11

RESULTS

GREENHOUSE GASES AFFECT GMS

ALONE

12

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗

ൗ𝟖𝟎. 𝟒 𝑪𝑾𝑽 − 𝟏. 𝟑

GHG does not influence Qdiv

Jalihal et al. (2019) Nat. Comm.

Qdiv

(m

m d

ay

-1)

RESULTS

ICE SHEETS AFFECT GMS ALONE

13

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗

ൗ𝟖𝟎. 𝟒 𝑪𝑾𝑽 − 𝟏. 𝟑

Ice sheets do not influence Qdiv

Jalihal et al. (2019) Nat. Comm.

Qdiv

(m

m d

ay

-1)

RESULTS

ORBITAL FORCING AFFECTS BOTH

GMS AND QDIV

14

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗

ൗ𝟖𝟎. 𝟒 𝑪𝑾𝑽 − 𝟏. 𝟑

Even though both Qdiv and GMS are influenced, GMS is dominant.

Jalihal et al. (2019) Nat. Comm.

Qdiv

(m

m d

ay

-1)

RESULTS

ORBITAL FORCING WITH GLACIAL

BOUNDARY CONDITIONS

15

𝑷 − 𝑬 =𝑸𝒅𝒊𝒗

ൗ𝟖𝟎. 𝟒 𝑪𝑾𝑽 − 𝟏. 𝟑

ORB: orbital parameters only. Constant LGM values for all other boundary conditions.

During cold periods, orbital forcing drives monsoon through GMS.

Jalihal et al. (2019) Nat. Comm.

Qdiv

(m

m d

ay

-1)

Energy available

Precipitation

1 2

Insolation

GMS

1 - Dominant during the Deglacial

2 - Dominant during the Holocene

Jalihal et al. (2019) Nat. Comm.

Energy available

GHG & Ice sheets

Precipitation

1 2

1 - Dominant during the Deglacial

2 - Dominant during the Holocene

Insolation

GMS

Jalihal et al. (2019) Nat. Comm.

Energy available

GHG & Ice sheets

Total column water vapor

Surface temperature

Precipitation

1 2

1 - Dominant during the Deglacial

2 - Dominant during the Holocene

Insolation

Jalihal et al. (2019) Nat. Comm.

Conclusions

19

CONCLUSIONS

CONCLUSIONS

• Changes in insolation is an initial trigger, final response involves feedbacks as well.

• Water vapor feedback amplifies solar forcing during deglacial.

• Cloud radiative feedback influences monsoon during Holocene.

20

CONCLUSIONS

CONCLUSIONS

• Insolation can drive monsoon through two different pathways.

• Greenhouse gases and ice sheets only affect GMS.

20

• Through energy available during warm periods, and through GMS during cold periods

Thank you

21

Extra Slides

22