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The Infinite Forecast

The Infinite Forecast. Ants Leetmaa and Gabriel Vecchi Geophysical Fluid Dynamics Laboratory NOAA/OAR Princeton, NJ 08542.

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The Infinite Forecast

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  1. The Infinite Forecast Ants Leetmaa and Gabriel Vecchi Geophysical Fluid Dynamics Laboratory NOAA/OAR Princeton, NJ 08542

  2. The next logical step after the NWP (24 hrs) forecasting project is to pass to longer range forecasts, and more generally speaking, to determination of the ordinary general circulation of the terrestrial atmosphere …..may be viewed as a forecast over an infinite period of time J. von Neumann July 29, 1955

  3. Sources of Predictability Weather • Current state of atmosphere • Deterministic, out to days in advance Seasonal Climate • Tropical ocean and land state • Probabilistic, next seasons of deviations from climatological* seasonal means Decadal to Centennial Projections • Changes in solar forcing, volcanoes, natural oscillations • Anthropogenic greenhouse gas – radiative forcing scenarios • Probabilistic, scenarios of future climatologies* *Climatology – a statement of “normal”- typically averages over 30 years of means, extremes, etc. Linkages exist between centennial – seasonal – weather regimes

  4. GFDL Science and Computer Advances Volcanic aerosols and feedbacks on AO Start detection & attribution; multiple GHG forcings; natural variability and forcings important; ensembles IPCC 2007 1st 3-D sim of chem-transport-rad features of Antarctic ozone hole Coupled ENSO forecasts 1st simulation of H2O, cloud-rad, ice-albedo feedbacks Coupled ocean/atmos 100 yr run: 1st IPCC model 1st estimates of effects of 2xCO2

  5. Climate Scenarios Being Run for 2007 IPCC What can we learn from these about the slow and fast modes of climate variations?

  6. Preliminary Results from IPCC 2007 Runs Changes to general circulation • Hadley and Walker cells • Season mean Impacts of change on climate variability – El Nino Southern Oscillation (ENSO)

  7. Changes to Hadley and Walker Circulations ( 500 mb vertical velocity field) % change 1860 Mean 1860 2X 4x minus 1860 2x Slow down of tropical/subtropical circulations associated with redistributions of tropical rainfall

  8. Surface temperature rainfall U200 Z200 Changes in Mean Annual Cycle: DJF Note the development of a zonally and hemispherically symmetric component to the circulation anomalies – with strong impacts in midlatitudes

  9. Surface temperature rainfall U200 Z200 Changes in Mean Annual Cycle: SON The poleward expansion of the subtropical highs is most pronounced in fall and summer. 1860 relative to 1990 shows equatorward movement of highs.

  10. Changes to Tropical Variability with Planetary Warming Increasing CO2 NINO3 SST reversed 1860 spinup 1990 CO2 CO2 increasing 1%/yr 0.5 1 Power Spectrum Period (yr) 2 4 8 135yr

  11. 1860 1990 obs greenhouse NINO3 SST Spectrum Period (years)

  12. Changes to Spatial Structure and Amplitude of ENSO (As evidenced in 500 mb vertical velocity field) 4X 2X

  13. Changes in Amplitude of ENSO Teleconnections: DJF

  14. Summary – Physical Climate A richness of tropical forced responses are important on a variety of time scales Hadley and Walker cells slow down with global warming • Tropical convection becomes more zonally symmetric • Convective – radiative equilibrium might play role in slowing Seasonal circulation patterns become more zonally symmetric • Subtropical highs expand northward (or southward)– especially summer/fall – depending on warming (or cooling) of tropics • Midlatitudes experience greater drying tendencies with warming ENSO temporal structure doesn’t change significantly • Suggestion of stronger and longer duration events with warming – predictability possibly is greater • Increased chances of more “100 year” events • Teleconnection patterns are more robust with warming • Decadal variability of ENSO can confound warming signal and is important in decadal midlatitude climate fluctuations (droughts, etc.)

  15. atmosphere weather Hyro-land Seasonal climate ocean Sea ice Earth System - prototype in 2005 Land carbon Ocean-carbon NPZ Atmospheric chemistry Link to coastal ecosystem models NOAA’s Future Environmental Forecasts NOAA – now Natural disaster reduction Improved seasonal & drought Coastal runoff NOAA – Next Natural disaster reduction Water resources – weather and climate Decadal fcsts Sea Level Arctic ice/climate CO2 uptakes Prototype coastal & ocean ecosystems Local &Global air quality & dust NOAA–after-Next Natural disaster reduction Water quantity and quality Marine ecosystem regime shifts Ocean health Energy & insurance management Terrestrial ecoystem yields (crops) Coastal blooms and hypoxia Global chemistry & Climate and Health Weather and Climate models built on community based software standards

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