Future Changes in Land-Atmosphere Feedback
over India
J.Sanjay, M.V.S. Ramarao, R. Krishnan
Centre for Climate Change Research (CCCR)
Indian Institute of Tropical Meteorology (IITM), Pune
INDIA• Soil moisture affects the partitioning of net radiation between sensible
and latent heat flux to the atmosphere• The feedback from land to atmosphere can occur through two landatmosphere coupling pathways:•Water cycle - changes in evapotranspiration and its variability influence
atmospheric humidity, stability, cloud formation, and precipitation (e.g.,Koster et al. 2006 and others)•Energy cycle - Surface sensible heat flux drives growth of the boundary
layer, enabling the formation of clouds by mixing moist air upward to theheight where temperature and pressure allow condensation to occur (e.g.,Betts et al. 1996 and others)• The Coupled Model Intercomparison Project Phase 5 (CMIP5) model
simulations project increases in land-atmosphere feedback throughwater cycle and energy cycle (Dirmeyer et al. 2013, 2014)• This study examines the thermally driven land-atmosphere coupling
pathway through the energy cycle in the high resolution downscaled
regional climate change projections available from CORDEX South Asia

Thermal Land Surface Controls on the Atmosphere

Dirmeyer et al. 2014, GRL• Multi-model mean of 10 CMIP5AOGCMs during JJA (1916-2005)• Atmosphere segment: Sensitivityof the height of LCL above groundin pressure co-ordinates (PLCL) tosensible heat flux (H)• These differentials are estimated as theslope of the linear regression through thedetrended monthly values for theselected years of simulation estimatedseparately for each month of the year

• Land segment:
Sensitivity of H to surface soil
moisture (w)• Total feedback path
• Striping indicates where at least 8 models
concur on an increase (vertical) or decrease(horizontal) in RCP8.5

Dirmeyer et al. 2014, GRL

Intensified land surface control onboundary layer growth in a changing climate

Atmosphere segment•

Land-atmosphere feedback
goes from soil moisture tosensible heat to PBL growth•This feedback pathway islikely to strengthen in a
warming climate•Sensitivity to land usechange and climate
extremes may amplify in thefuture

Land segment

Total feedbackLand-Atmosphere coupling plays a critical role ininfluencing the South Asian monsoon climate variability• Sensitivity study using WRF (45 km) by replacing the soil moistureevolution at each time step with its climatology (2000-2011) takenfrom the control run• Soil moisture makes a significant
contribution to monsoon (large-scale) rainfall
variability over the monsoon region• Soil moisture is found more strongly coupled
to sensible heat flux over most of themonsoon region• The coupling of the soil moisture totemperature and rainfall over central India
is operated mainly through sensible heat flux
• The monsoon trough region, northwest region, andsoutheast India exhibit a strong coupling of soil moistureand boundary layer height.

CCCR, IITM is leading CORDEX (Coordinated Regional
Climate Downscaling Experiment) over South Asia Region

CORDEX South Asia Experiments with IITM-RegCM4 50km
• RCM: ICTP RegCM4.4.5 + CLM4.5• CMIP5 Downscaling ofHistorical(56y;1950-2005),
RCP4.5(94y;2006-2099),
RCP8.5(94y;2006-2099)• Driven with 6 CMIP5 AOGCMs: GFDL-ESM2M, CNRM-CM5,
CSIRO-Mk3.6, MPI-ESM-LR,
IPSL-CM5A-LR & CanESM2• IITM-RegCM4 outputs are published on CCCR-IITM
ESGF data node after quality assurance as per
CORDEX archival specifications.
http://cccr.tropmet.res.in/home/cordexsa_datasets.jsp

ESGF Data Node @ CCCR-IITM
http://cccr.tropmet.res.in/home/esgf_node.jsp

Changes in Downscaled Regional Climate Projections
from CORDEX South Asia
Precipitation

Historical(1951-2005)

Surface Soil Moisture• Ensemble mean of 6
regional climate
projections
downscaled with
IITM-RegCM4 RCM

ProjectedChange(2006-2099)

RCP 4.5RCP 8.5• Striping indicates whereat least 4 realizations
concur on an increase(vertical) or decrease(horizontal) in RCPs.

Thermal Land Surface Controls on the Atmosphere
during Summer Monsoon Season• Ensemble mean of 6 regional climate projections
downscaled with IITM-RegCM4 RCM• Atmosphere segment: Sensitivity of the height of
LCL above ground in pressure co-ordinates (PLCL) tosensible heat flux (H)• Land segment:
Sensitivity of H to surface soil moisture (w)• Total feedback pathIntensified land surface control onboundary layer growth in a changing climate

Atmosphere segment

Land segment

Total feedback• Striping indicates where at least
4 realizations concur on an increase(vertical) or decrease (horizontal) in RCPs.

Summary• Regional climate projections downscaled with IITM-RegCM4 RCM forhistorical and future climate scenarios are examined for changes inthe energy cycle component of land surface feedback on theatmosphere• Land-atmosphere feedback links from soil moisture to sensible heat
flux to growth of the atmospheric boundary layer• Projected changes indicate increased sensitivity in both of thesesegments of the feedback pathway over the monsoon trough region• With increased sensitivity, the summer soil moisture variations could
have more impact on regional climate than they do today

Latest updates• Summary of 17 CORDEX South Asia 0.44° datasets
available on ESGF (~20 TB)• IITM-RegCM4: Hist (6);RCP8.5 (6); RCP4.5 (6)• SMHI-RCA4 :Hist (10); RCP8.5 (10); RCP4.5 (10); RCP2.6 (5)• CSC-REMO2009: Hist (1); RCP8.5 (1);RCP4.5 (1); RCP2.6 (1)http://cccr.tropmet.res.in/home/cordexsa_datasets.jsp• Future climate change projections over India assessedusing CORDEX South Asia RCM outputs• Available at http://cccr.tropmet.res.in/home/reports.jsp• The new information available from CORDEX South Asia are founduseful for contributing to the Hindu Kush Himalayan Monitoring andAssessment Programme (HIMAP; http://www.icimod.org/himap)•Sanjay et al. (2017), Advances in Climate Change Research,doi: 10.1016/j.accre.2017.08.003

Future Plans• Apply bias-correction to the CORDEX South Asia RCM outputs and publish
on CCCR-IITM ESGF data node as CORDEX-Adjusted datasets• CCCR-IITM is developing a global high resolution (27km) atmosphericversion of the IITM Earth System Model for future downscalingactivities
Pan-WCRP Modelling Meeting, Exeter, October 9-13

Thanks for your attention
Email: sanjay@tropmet.res.in

Thank You• JMBSC, MRI, JMA• CCCR-IITM, MoES, GoI