MRC London April 5 th 2005 The atmospheric

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MRC, London, April 5 th 2005 The atmospheric hydrological cycle and climate feedbacks: past,

MRC, London, April 5 th 2005 The atmospheric hydrological cycle and climate feedbacks: past, present and future Richard Allan Environmental Systems Science Centre, University of Reading

Climate Change How the hydrological cycle responds to global warming is crucial to mankind

Climate Change How the hydrological cycle responds to global warming is crucial to mankind (e. g. water supply, agriculture, severe weather, ecosystems)

Earth’s Radiation balance and climate S~1367 Wm-2 Solar/SW Thermal IR/LW or Outgoing Longwave Radiation

Earth’s Radiation balance and climate S~1367 Wm-2 Solar/SW Thermal IR/LW or Outgoing Longwave Radiation (OLR) • (S/4)(1 -Albedo) – OLR = 0 (at balance) • 2 x. CO 2 ~ 4 Wm-2 less OLR heating • Feedback: response of system is crucial to magnitude and nature of climate change

How will climate and global water cycle respond to increasing greenhouse gases? • IPCC(1990)

How will climate and global water cycle respond to increasing greenhouse gases? • IPCC(1990) 2 x. CO 2 sensitivity d. Ts ~ 1. 5 – 4. 5 K Stainforth et al. (2004) Nature Climate Sensitivity (K)

Aims and Strategy • Aim – to reduce uncertainty in climate prediction and climate

Aims and Strategy • Aim – to reduce uncertainty in climate prediction and climate impacts using EO data – to understand the likely response of the hydrological cycle to increased greenhouse gases • Strategy: – Monitor present-day and past changes in hydrological cycle – Identify physical models – Uncover previously unidentified processes

Previously unidentified process involving cloudiness and ocean heat storage? IPCC (2007) in preparation, provided

Previously unidentified process involving cloudiness and ocean heat storage? IPCC (2007) in preparation, provided by B. A. Wielicki

Decadal-scale passive microwave data: monitoring column integrated water vapour

Decadal-scale passive microwave data: monitoring column integrated water vapour

Identify physical models

Identify physical models

Increases in water vapour with temperature imply an enhanced atmospheric hydrological cycle water vapour

Increases in water vapour with temperature imply an enhanced atmospheric hydrological cycle water vapour and temperature atmospheric cooling global water cycle

Concluding remarks • Timeliness: why now? – EO-data beginning to resolve decadal time-scales –

Concluding remarks • Timeliness: why now? – EO-data beginning to resolve decadal time-scales – Apparent uncertainty in climate model predictions are becoming larger, not smaller! • What is different? – Encompass entire hydrological cycle – a 5 -year challenge – Earth-system strategy: analysing interactions between global water cycle, radiative cooling, latent heating and atmospheric circulation using EO data – “Fast” and “Slow” feedbacks – Regional and regime-dependent interactions

Work plan • WP 1 – Identification and intercomparison of datasets on hydrological cycle

Work plan • WP 1 – Identification and intercomparison of datasets on hydrological cycle (year 1) – e. g. SSM/I, CERES, CMAP, da. Silva, CLAUS… – Development of surface and atmospheric flux capability • WP 2 – Spatial and temporal variability (years 1 -2) – Spatial, daily, seasonal, interannual, ENSO, decadal • WP 3 – Identification of regional and dynamical regime feedbacks + techniques (years 2 -4) • WP 4 – Identification of physical models (years 3 -5) – Reduction in uncertainty of climate sensitivity

Met Office, Hadley Centre Griggs, Ringer GFDL Ramaswamy NASA Langley Wielicki, Wong University of

Met Office, Hadley Centre Griggs, Ringer GFDL Ramaswamy NASA Langley Wielicki, Wong University of Miami - Soden Meteorology Department – Links Shine, Hogan ESSC ECMWF Simmonds Morcrette Imperial College Harries