high-resolution modelling of regional climate change scenario over south asia r. krishnan

High-resolution modelling of regional climate change scenario over South Asia

R. Krishnan Centre for Climate Change Research

Indian Institute of Tropical Meteorology, Pune

Seminar on Socio Economic Implications of Climate Change Initiatives:

Priorities and Implications for India

Geospatial World ForumHyderabad

18 – 21 January, 2011

An Elegant Science Question: An Elegant Science Question: Are increases in greenhouse gases responsible for

increase in global mean temperature (global warming)?

0.76°C (1.4°F) since 1900

0.55°C (1.0°F) since 1979

395

365

335

305

275

14.6

14.4

14.0

13.8

13.4

14.2

13.6

Global Temperature & Carbon Dioxide 1860-2008

• Greenhouse gases increase due to human activities.

• Global warming is due to increases in greenhouse gases.

• Global warming is due to human activities.

HypothesisHypothesis

Alternative HypothesisAlternative Hypothesis

• Global warming is due to natural variations of climate.

How do you test such hypotheses?

Climate Models; IPCC

• Equations of motions and laws of thermodynamics to predict rate of change of:

T, P, V, q, etc. (A, O, L, CO2, etc.)

• 10 Million Equations: 100,000 Points × 100 Levels × 10 Variables

• With Time Steps of: ~ 10 Minutes

• Use Supercomputers

What is a Climate Model?What is a Climate Model?

IPCC 2007

1.0º C1.0º C

Increase in Surface TemperatureIncrease in Surface Temperature

ObservationsPredictions with Anthropogenic/Natural forcingsPredictions with Natrual forcings

Challenges in assessment of future changes in South Asian monsoon

rainfall

•Wide variations and uncertainties among the IPCC AR4 models in capturing the mean monsoon rainfall over South Asia (eg., Kripalani et al. 2007, Annamalai et al. 2007).

•Systematic biases in simulating the spatial pattern of present-day mean monsoon rainfall (eg., Gadgil and Sajani, 1998; Kripalani et al. 2007)

•Realism of present-day climate simulation is an essential requirement for reliable assessment of future changes in monsoon

South Asia

(5-35N, 65-95E))

Source: Kripalani et al. 2010

Summer monsoon precipitationSummer monsoon precipitation

IPCC models: 20C3M1979-1998Observed rainfall (JJAS)

The 20c3m simulations attempt to replicate the overall climate variations during the period ~1850-present by imposing each modeling groups best estimates of natural (eg., solar irradiance and volcanic aerosols) and anthropogenic (eg. GHG, sulfate aerosols and ozone) during this period. Seven 20C3M models (GFDL CM2.0, GFDL-CM2.1, MPI-ECHAM5, MRI, MIROC3-HIRES, HadCM3, NCAR-PCM – Source: J. Shukla)

1999 2000

2005

2001 2002 2003 2004

2007 20082006 2009 2010

Long-term mean of JJAS rainfall (mm)

JJAS cumulative rainfall (1951-2009) Area average (90E – 97E ; 20N – 30N)IMD gridded rainfall dataset

http://www.tropmet.res.in

Interannual variability of monsoon rainfall over Northeast India

Questions : On Attribution?Questions : On Attribution?

How much of the observed variability of the mean Indian How much of the observed variability of the mean Indian Summer Monsoon rainfall due to Climate Change?Summer Monsoon rainfall due to Climate Change?

How much of the observed increase in temperature over India How much of the observed increase in temperature over India been decreased by increasing presence of aerosols?been decreased by increasing presence of aerosols?

Questions : On Projections of Questions : On Projections of MonsoonMonsoon

What will happen to the monsoon hydrological cycle 50-100 What will happen to the monsoon hydrological cycle 50-100 years from now under different scenarios? In particular, will the years from now under different scenarios? In particular, will the quantum of seasonal mean rainfall increase or decrease and if so quantum of seasonal mean rainfall increase or decrease and if so by how much?by how much?

What is the uncertainty in these projections? Can we quantify What is the uncertainty in these projections? Can we quantify this uncertainty?this uncertainty?

How can we reduce this uncertainty?How can we reduce this uncertainty?

Some indicators of regional monsoon climate

•Observed changes in frequency of monsoon depressions during the last century

•Changes in the observed extreme rainfall events during the 20th century

Question:

Attribution: How much of the observed regional monsoon variability is due to global warming?

All India summer monsoon rainfall variability

Climatological Mean (JJAS)

Interannual Variability

Goswami et al., Science, 2006

Time series of count over CI

Low & Moderate events

Heavy events (>10cm)

V. Heavy events (>15cm)

•Frequency as well as intensity of heavy & very-heavy rainfall events have significantly increased over Central India

•Low and moderate events have significant decreasing trend over Central India

•The seasonal mean does not have a trend because decreasing contribution from low and moderate events are compensated by increasing contribution from heavy events

• Increase in intensity of extreme events

Goswami et al 2006

Possible causes for the decreasing trend in the moderate Possible causes for the decreasing trend in the moderate rainfall events ?rainfall events ?

Long-term trends in the large-scale monsoon circulation ?Long-term trends in the large-scale monsoon circulation ?

Indications of weakening of the low-level monsoon flow Indications of weakening of the low-level monsoon flow (Joseph and Simon 2005)(Joseph and Simon 2005)

Increasing frequency of “breaks” in monsoon rainfall Increasing frequency of “breaks” in monsoon rainfall (Ramesh Kumar et al. 2009)(Ramesh Kumar et al. 2009)

Zonal wind averaged over (12.5N – 17.5N; 70 E – 85 E)

1950-2002

•Decreasing frequency of monsoon depressions during last 2-3 decades (eg., Rajeevan et al., 2000; Amin and Bhide, 2003; Dash et al., 2004)

•Recovery in the activity of monsoon depressions during the recent years (2005 – 2007)

•Activity of monsoon depressions modulated by low-frequency variability of atmospheric large-scale circulation on inter-decadal time-scales

Time series of frequency of monsoon depressions

Strategy on Regional Strategy on Regional Climate Change Research at IITMClimate Change Research at IITM

Centre for Climate Change Research (CCCR)Centre for Climate Change Research (CCCR)Ministry of Earth Sciences, Govt. of IndiaMinistry of Earth Sciences, Govt. of India

To build capacity in the country in high resolution coupled To build capacity in the country in high resolution coupled ocean-atmosphere modelling to address issues on ocean-atmosphere modelling to address issues on Attribution Attribution and Projection and Projection of regional Climate Changeof regional Climate Change

Earth System Model (ESM)Earth System Model (ESM)

To provide reliable input for Impact Assessment studies To provide reliable input for Impact Assessment studies Dynamic downscaling of regional monsoon climate using high Dynamic downscaling of regional monsoon climate using high

resolution models; quantification of uncertaintiesresolution models; quantification of uncertainties

Observational monitoring: Network with other Institutions Observational monitoring: Network with other Institutions

CCCR

Administration Scientific Research Outreach

Modelling Program Observational Program

To establish a High Altitude Cloud Physics Observatory for monitoring cloud-aerosol interactions – (Long-term)

To understand Past Changes in Monsoon Climate using Multiple Proxy Records. Reconstruction of an iconic monsoon index going back to a few thousand years – (Long-term)

To promote Outreach and Training for Capacity Building in Climate Change Research and Dissemination of Information – Long-term cont

To build a Global High-resolution Earth System

Model to address the Attribution & Projection of

regional climate change – (Long-term)

To generate regional climate change scenarios for

South Asia using Ultra High-resolution Regional

Climate Models and quantify uncertainties.

Provide reliable inputs for impact assessments.

Contribute to IPCC AR5 – (Short-term)

Objectives

High resolution regional climate change scenarios and quantification of uncertainties

Provide reliable inputs for impact assessments and contribute to IPCC AR5

High resolution dynamic downscaling of monsoon: Baseline climate runs using WRF, RegCM and LMDZ partially completed. Future climate scenario runs to be initiated in January 2011.

Two member 19 year (1989 : 2007) run of WRF (50 km) model completed. ERA Interim LBC

One member 19 year (1989 : 2007) run of RegCM (50 km) model completed. ERA Interim LBC

One member 10 year (1979 : 1988) run of LMDZ (50 km) model completed

CRU

ERAIM

WRF – KF2

CRU

ERAIM

WRF – BM

CRU

ERAIM

RegCM - EML

CRU

ERAIM

RegCM - GRL

CRU

ERAIM

PRECIS

CRU

ERAIM

LMDZ

Jan Apr Jul Oct Jan Apr Jul Oct

Monthly mean annual cycle of surface air temperature over Indian land region

Jan Apr Jul Oct Jan Apr Jul Oct

IMD

CMAP

WRF – KF2

IMD

CMAP

WRF – BM

IMD

CMAP

RegCM - EML

IMD

CMAP

RegCM - GRL

IMD

CMAP

PRECIS

IMD

CMAP

LMDZ

Monthly mean annual cycle of precipitation (mm/day) over Indian land region

LMD model

1 degree (Global)

LMDZ model

1/3 degree zoom for

Monsoon Domain

(40-110E; 15S-30N)

&

1 degree outside

Initial runs made at CCCR on PRITHVI, IITM

JJAS SLP and winds 850 hPaJJAS rainfall

High resolution monsoon simulations: Global model with zoom over monsoon domain

LMDZ monsoon simulation at 50 km zoomed resolution – 10 year mean

Mean SLP and 850 hPa winds (JJAS) Mean rainfall (JJAS)

•Large scale structure of winds and SLP is well captured

•Monsoon Trough has strong southward dip over eastern India and Bay of Bengal – Bias

•Precipitation along West Coast and Central - Eastern India is reasonably well simulated

•Rainfall over north Bay of Bengal is underestimated. Excessive rain over central Bay of Bengal

•Rainfall over Equatorial Eastern Indian Ocean is underestimated

Example of a monsoon depression in a typical synoptic chart

LMDZ simulation: Rainfall and 850 hPa streamlines during a typical monsoon low / depression

Day 01 Day 02 Day 03 Day 04




LMDZ simulation: Evolution of SLP anomalies during a typical monsoon depression





Earth System Model (ESM) development

Start with an atmosphere-ocean coupled model which has a realistic mean climate – eg. NCEP CFS Fidelity in capturing the global and monsoon climate Realistic representation of monsoon interannual

variability Features of ocean-atmosphere coupled interactions …

Include components of the ESM Aerosol and Chemistry Transport Module Biogeochemistry Module (Terrestrial and Marine) Sea-ice module … .

Climatological (JJAS) mean monsoon rainfall from CFS model – 100 year free run

Climatological (JJAS) mean SST from CFS model – 100 year free run

Taylor diagram of spatial pattern of climatological seasonal mean (JJAS) rainfall

CFS Model

High pattern correlation with observed rainfall over India (IMD gridded Dataset)

Source: Seasonal Prediction Group, IITM

CFS modelJJAS climatological mean rain rate = 5.80 mm / day (red line) Standard Deviation of JJAS rain rate = 0.82 mm / day

Observed rainfall (IMD)JJAS climatological mean rain rate = 7.5 mm /day Standard Deviation = 0.85 mm / day

Interannual variability of summer monsoon rainfall in the CFS model – 100 year free runDomain: 70E-90E; 10N-30N

Time in years

CFSv2 precip JJAS 10 yr mean CMAP precip JJAS (1980-2009)

CFSv1 precip JJAS 100 yr mean

CFSv2 runs on PRITHVI by CCCR

Ongoing efforts towards development of Earth System Model (ESM) to address the Scientific Challenges of Global Climate Change and the Asian Monsoon System

Plan to include ESM components in the CFS-2 coupled ocean-atmosphere modelPlan to include ESM components in the CFS-2 coupled ocean-atmosphere model

CFS-2 coupled ocean-atmosphere model simulations on HPC initiatedCFS-2 coupled ocean-atmosphere model simulations on HPC initiated

Ocean Biogeochemistry Module coupled to MOM4. Runs are ongoing on HPCOcean Biogeochemistry Module coupled to MOM4. Runs are ongoing on HPC

Aerosol Transport Module coupled to AGCM. Runs are ongoing on HPCAerosol Transport Module coupled to AGCM. Runs are ongoing on HPC

Basic structure

of ESM

CCCR

Features of Dynamic Climate Data Portal

Visualize data with on-the-fly graphic

Easy and user friendly analysis of climate data through graphical display on the browser with one click

Example : IMD daily rainfall (1951 to 2009)

URL: http://cccr.hpc:8080/CCCR

Step 1: Click on the above URL

Centre for Climate Change Research

Indian Institute of Tropical Meteorology, Pashan , Pune – 411 008

Ministry of Earth Sciences, Govt. of India

CCCR Climate Data Web Portalhttp://www.cccr.res.in

Summary Dynamic downscaling of regional monsoon climate using high resolution models. Efforts have been initiated at CCCR.

Downscaling simulations of present day and future monsoon climate scenarios will be completed by early 2012 (PRECIS, WRF, RegCM, LMDZ)

Contribute to IPCC AR5 report through its activity

Quantify uncertainties in regional monsoon projections using results from multiple models

Also employ bias correction techniques for reducing model errors

Share model data & conduct inter-disciplinary collaborative research towards impact assessment, vulnerability and adaptation.

Hydrological Modeling to be started at CCCR soon

Long term plans (~ 3-4 years) to develop an Earth System Model (ESM)A global atmosphere-ocean coupled model (CFS) is operational. A century long simulation and several other runs have been performed

Aspects of global and regional monsoon climate are realistically captured by CFS model

Realistic features of monsoon interannual variability is seen from the CFS simulations (e.g., Atmosphere-ocean coupling over tropical Indo-Pacific, Monsoon and mid-latitude interactions, etc)

Plans to improve the simulation of present day monsoon climate in the CFS model. Need to reduce model systematic biases.

Ongoing efforts to include ESM components in CFS model (ie., Aerosol transport module, Marine and Terrestrial Ecosystem and Biogeochemistry module, Sea-Ice module, etc).

high-resolution modelling of regional climate change scenario over south asia r. krishnan

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