# Presentation: 495385

## The Infinite Forecast

- Ants Leetmaa and Gabriel Vecchi
- Geophysical Fluid Dynamics Laboratory
- NOAA/OAR
- Princeton, NJ 08542

## 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

## 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

- 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

**Sources of Predictability**

## GFDL Science and Computer Advances 

**1****st**** simulation of H2O, cloud-rad, ice-albedo feedbacks**

**1****st**** 3-D sim of chem-transport-rad features of Antarctic ozone hole**

- GFDL Science and Computer Advances

**Volcanic aerosols and feedbacks on AO**

**Coupled ocean/atmos 100 yr run: 1****st**** IPCC model**

**1****st**** estimates of effects of 2xCO2**

**Coupled ENSO forecasts**

**Start detection & attribution; multiple GHG forcings; natural variability and forcings important; ensembles**

**IPCC 2007**

##  Climate Scenarios Being Run for 2007 IPCC 

** ****Climate Scenarios Being Run for 2007 IPCC**

- What can we learn from these about the slow and fast modes of climate variations?

## 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)

## Changes to Hadley and Walker Circulations

**2x**

**1860**

**1860 Mean**

**4x minus 1860**

**% change**

- Slow down of tropical/subtropical circulations associated with redistributions of tropical rainfall

- ( 500 mb vertical velocity field)

**2X**

## 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

## 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.

## Changes to Tropical Variability with Planetary Warming

- reversed 1860 spinup

- 1990 CO2

- CO2 increasing 1%/yr

- NINO3 SST

- Power Spectrum

- 1

- 4

- 0.5

- 2

- 8

- Increasing CO2

- Period (yr)

- 135yr

## NINO3 SST Spectrum

- Period
- (years)

## Changes to Spatial Structure and Amplitude of ENSO

- (As evidenced in 500 mb vertical velocity field)

**2X**

**4X**

## Changes in Amplitude of ENSO Teleconnections:  DJF

## 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.)

## 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