Enso prediction and policy
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ENSO Prediction and Policy. Why Predict ENSO? How do we predict ENSO? Why is it possible ? What information do predictions offer? What to do with this information? An on-the-ground policy application…. Why does ENSO State tend to Oscillate?. Equatorial ocean dynamics

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ENSO Prediction and Policy

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Enso prediction and policy

ENSO Prediction and Policy

  • Why Predict ENSO?

  • How do we predict ENSO?

  • Why is it possible ?

  • What information do predictions offer?

  • What to do with this information?

  • An on-the-ground policy application…


Why does enso state tend to oscillate

Why does ENSO State tend to Oscillate?

Equatorial ocean dynamics

Key observations by Klaus Wyrtki in 1970’s

El Nino is preceded by a transfer of warm water from west to east

This transfer is thought to trigger a warm event

What triggers the movement of water?

  • In cold phase, waters cold (and low) in east, warm (and high) in west

  • Warm water from west sloshes back and overshoots equilibrium- positive feedbacks mentioned before set of El Niño conditions


Enso prediction and policy

Why does ENSO State tend to Oscillate?

Shortest Answer:

Equatorial ocean dynamics

Short answer: Differing timescales of Kelvin and Rossby Wave propagation

Longer answer: The oscillation is made possible due to the asymmetry between eastward and westward oceanic motions (see 2-D Animation in notes).

Along the equator there is a relatively fast eastward motion called an equatorial Kelvin wave. Peaking somewhat off the equator are westward motions called Rossby waves. Time scale: <1 yr for the Kelvin waves to shift the warm pool eastward [once trades relax]; 2 yrs for the Rossby waves to return the warm pool to the west, to await another wind relax.

Kelvin

Rossby


Enso prediction and policy

Here is a 3-D animation the tropical Pacific as it cycles through an El Niño then La Niña event. The surface shown is sea-level (in cm) and the surface is colored according to the SST anomalies associated with each event.


Normal conditions in the tropical pacific

Normal Conditions in the tropical Pacific

Sea level pressure

Sea surface temperatures

Trade winds

Walker circulation

Equatorial upwelling

Thermocline depth

Sea surface height

Tropical rainfall patterns


El ni o conditions

El Niño Conditions

Sea level pressure

Sea surface temperatures

Trade winds

Walker circulation

Equatorial upwelling

Thermocline depth

Sea surface height

Tropical rainfall patterns


La ni a conditions

La Niña Conditions

Sea level pressure

Sea surface temperatures

Trade winds

Walker circulation

Equatorial upwelling

Thermocline depth

Sea surface height

Tropical rainfall patterns


Enso prediction and policy

What’s going to happen?

Forecasts courtesy of IRI (Lamont-Doherty)


Sstanomalies this week 5 11 oct 2014

SSTanomalies this week (5-11 Oct. 2014)


What will next week month quarter look like

What will next week/month/quarter look like?

?


Enso prediction and policy

Societal impact of ENSO in the news

Indonesia Flooding

Hawaii Drought

2010 news…


How enso impacts people

How ENSO impacts people

Effective management of climate related risks (opportunities) for improved:

  • Agricultural production

    • Stocking, cropping calendar, crop selection, irrigation, insurance, livestock/trade

  • Water resource management

    • Dynamic reservoir operation, power generation, pricing/insurance

  • Food security

    • Local, provincial, regional scales

  • Public health

    • Warning, vaccine supply/distribution, surveillance measures,…

  • Natural resource management

    • Forests/fire, fisheries, water/air quality

  • Infrastructure development


Enso prediction and policy

Malaria and Rainfall

The disease is highly seasonal and follows the rainy season with a lag of about 2 months


Enso and zimbabwe corn yield

ENSO and Zimbabwe corn yield

-

ENSO

+


Predictions and policy

Predictions and Policy

Snapshots of current conditions are not very useful.

People need advance warning, and for their region.

Today:

1) how predictions are made

2) what we can do with them


Enso prediction methods

ENSO Prediction Methods

  • Skillful 6-9 months into the future

  • This ability has saved many millions of lives

  • Two methods: Dynamical vs. Statistical


Enso prediction and policy

El Niño Forecasting

Stephen E. Zebiak

Senior Research Scientist

International Research Institute

for Climate Prediction

Mark Cane

DEES

Vetlesen Professor


Real time ocean observations

ARGO floats

XBT (eXpandable BathiThermograph)

Moorings

Satellite

SST

Sea Level

Real Time Ocean Observations

M.A. Balmaseda ( ECMWF)


Enso prediction and policy

ARGO drift sensors


Enso prediction and policy

TOGA TAO mooring array

M.A. Balmaseda ( ECMWF)


Enso prediction and policy

Tropopause

SSTA

Simplified Ocean and Atmosphere Models

50 m

150 m

Active layer

Deep ocean; u=v=w=0

Surface layer

Simplified form of equations for conservation of mass, momentum, energy


Enso prediction and policy

Climate Models


Enso prediction and policy

Forecast Initialization Procedures

Ocean

simulation

Atmos.

simulation

Winds,

Heat

fluxes

Ocean

obs.

Atmos.

obs.

SST

forcing

Data assimilation

Ocean analysis

Atmos. analysis

t  t + t

t  t + t

Initial Conditions, t=t0

Ocean model

Atmosphere model

FORECAST


Enso prediction and policy

Modeling gives you skill at forecasting:

Better skill after 3-4 months than “persistence”

Skillful up to 9 months into future


Enso prediction and policy

Correlation Skill for NINO3 forecasts


Enso prediction and policy

NINO3 Predictions


Enso prediction and policy

ENSO Prediction “Plumes”


Enso prediction and policy

How to predict?

Forecasts courtesy of IRI (Lamont-Doherty)


Enso prediction and policy

How is forecasting possible?

The tropical ocean-atmosphere system is coupled.

Models are initialized with real observations

The system has persistence (“memory”)


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