[email protected] © University of Reading 2009 1 Monitoring and understanding current changes in the global energy & water cycles Richard Allan

[email protected]© University of Reading 20091

Monitoring and understanding current changes in the global energy & water cycles

Richard Allan


• Increased Precipitation• More Intense Rainfall• More droughts• Wet regions get wetter,

dry regions get drier

Precipitation Change (%)

CLIMATE MODEL PROJECTIONS IPCC WGI

Precipitation Intensity

Dry Days


Scenario

Feedbacks

e.g. Hawkins & Sutton (2009) BAMS

• How will the water cycle respond to warming?• Can we effectively monitor current changes in the

Earth’s energy balance and water cycle?• What information can Earth Observation datasets

provide on cloud feedbacks? Are cloud feedback/water cycle issues linked?

• Can we provide near-real time monitoring of models and observations using satellite data?


Some background

• Joke slide

“Does anyone want to buy my nearly-

new research student?”


Winning my freedom from Met Office…(but only as far as ESSC)

Some background


Winning my freedom from Met Office…(but only as far as ESSC)

Important numbers!

Some background


Low-level water vapour rises with temperature at ~7%/K in models & observations

John et al. (2009) GRL; Allan (2009) J Climate

models

Wat

er V

apou

r (m

m)


1979-2002

For a given precipitation event, more moisture would suggest more intense rainfall

Can realism of model projections be assessed?


Frequency of rainfall intensities vary with

SST in models and obs

• Frequency of intense rainfall increases with warming in models and satellite data

• Model scaling close to 7%/K expected from Clausius Clapeyron

• SSM/I satellite data suggest a greater response of intense rainfall to warming

dP/dSST=7%/K

Allan and Soden (2008) Science

[email protected]© University of Reading 200910 Trenberth et al. (2009) BAMS


Models simulate robust response of clear-sky radiation to warming (~2-3 Wm-2K-1) and a resulting

increase in precipitation to balance (~3 %K-1) e.g. Allen and Ingram (2002) Nature, Stephens & Ellis (2008) J. Clim

Rad

iativ

e co

olin

g, c

lear

(W

m-2K

-1)

Allan (2009) J Clim


Contrasting precipitation response expected

Pre

cipi

tatio

n Heavy rain follows moisture (~7%/K)

Mean Precipitation linked to

radiation balance (~3%/K)

Light Precipitation (-?%/K)

Temperature

e.g.Held & Soden (2006) J. Clim; Trenberth et al. (2003) BAMS; Allen & Ingram (2002) Nature


Contrasting precipitation response in ascending and descending portions of the tropical circulation

GPCP/NCEP Models

ascent

descent

Allan and Soden (2007) GRL

Pre

cipi

tatio

n ch

ange

(m

m/d

ay)


Future Plans


- NERC PREPARE project (Met Office; ETH Zurich)

- HadIR/JCRP projects (Met Office, NCEO)

- leading ERL special focus issue (with Beate Liepert)

- Planned UK/Danish Met Services NERC partnership grant on GPS ; NERC Changing Water Cycle program; NCEO; Royal Society

- Changes in African and Asian Rainfall (Grimes, Turner, NCAS)

Monitoring and understanding changes in the global energy/water cycles

Pre

cipi

tatio

n A

nom

aly

(mm

/day

)

Radiation

Anom

aly (W

m-2)

[email protected]© University of Reading 200916 Allan et al. (2007) QJRMS

2008

Are the cloud feedback and water/energy cycles issues linked?- Radiative and microphysical properties of marine stratiform cloud (Stephens, Colorado; ECMWF) and ice cloud (Hogan)- CloudSat/CALIPSO, GERB/CERES, SSM/I (NCEO, Imperial, NASA)- Surface and Atmospheric Radiation Budget and aerosol (NASA, ETH)


Continuous Monitoring of models and observations

Example 1:

Global water cycle and Earth’s energy balance

Essential Climate variables (ESA Harwell, NCEO)

Reanalyses for climate (ECMWF)


Continuous Monitoring of models and observationsExample 2: Model development with Met Office/NCAS from NWP (below,

Milton, Brooks) to climate (Ringer, Williams) via Cascade (Woolnough)

13th March | 14th March 2006

Model S

W albedo

2005 2006

Change in model minus GERB flux differences: relate to change in model physics implementation

Identify problem and fix: convective cloud decay time-scale

Monitor improvement using GERB/CloudSat

1 2

3

Allan et al. (2007) QJRMS

[email protected]© University of Reading 200919Courtesy of Jim Haywood

Continuous Monitoring of models and observationsExample 3: field campaigns (e.g. RADAGAST; GERBILS; FENNEC) and opportunistic case studies…

Met Office NAME modelNOAA17 satellite image 20 March 2009 10:06








Using GERB/SEVIRI to quantify radiative effects of persistent contrail cirrus


Conclusions• Radiative energy and water cycles

– fundamentally linked– crucial for climate impacts

• Combining observations with models and a robust physical basis is essential for– understanding current changes in climate– quantifying and assessing feedbacks operating– improving confidence in predictions

• Continuous monitoring of observations and model simulations enable us to– track current trajectory of climate change– detect surprises in the climate system– link and develop seamless prediction systems

Documents

[email protected] © University of Reading 2009 1 Monitoring and understanding current changes in the global energy & water cycles Richard Allan