How do we predict weather and How do we predict weather and climate?climate?

Review of last lectureReview of last lecture

Land-sea temperature contrasts: seasonal monsoonLand-sea temperature contrasts: seasonal monsoon

Extratropical climate:Extratropical climate: Mean state: westerly winds, polar vortexMean state: westerly winds, polar vortex The natural oscillations associated with The natural oscillations associated with

strengthening/weakening of polar vortex: AO, NAO, AAOstrengthening/weakening of polar vortex: AO, NAO, AAO Effect of global warming on polar vortexEffect of global warming on polar vortex What is the primary way El Nino affect extratropics? (PNA)What is the primary way El Nino affect extratropics? (PNA)

AstronomyMeteorologyAgriculture

FoodWeather

CommunicationTransportationEngineeringMaterialsEnergy

EnvironmentHealth

ComputerMechanicsChemistryPhysics Math

Earth SciBiology

0 500 1500 20001000500BC

Human Needs

Science

Middle Ages

Archimedes

Socrates Galileo

BrunoMadam Curie

Einstein

Time

Spirit of Independent Thinking

Individual Objects

Organic System

The Global Climate System - Atmosphere, The Global Climate System - Atmosphere, ocean, biosphere, cryosphere, and geosphereocean, biosphere, cryosphere, and geosphere

RadiationCloud/precipitation

Shallow convection Boundary layer turbulence

Mesoscale convective system ThunderstormTornado

Heat waveMidlatitude cycloneAtmospheric riverTropical cyclone

Diurnal variation

Madden-Julian Oscillation Tropical wavesAnnular modes

100,000yr100yr10yr1yr1mon1day1min1sec10-15sec

Global Climate System

Globe

Continent

State

City

Football field

1 mm

1 m

Spatial Scale

Time Scale

10-4 m Composition

Monsoon

ENSOQBO

Global warmingMulti-decadal Oscillation

Ice ageGlacial cycleAbrupt change

Video: Video: Predicting the forces of NaturePredicting the forces of Nature

https://www.youtube.com/watch?v=aC-q0CkBYIA https://www.youtube.com/watch?v=aC-q0CkBYIA

(-6:00, 38:40-)(-6:00, 38:40-)

General Circulation Model: BasicsGeneral Circulation Model: Basics

• General circulation models are systems of differential equations based on the General circulation models are systems of differential equations based on the basic laws of physics, fluid motion, and chemistry. basic laws of physics, fluid motion, and chemistry.

• Scientists divide the planet into a 3-dimensional grid (Scientists divide the planet into a 3-dimensional grid (100-500 Km wide100-500 Km wide), apply the ), apply the basic equations within each grid and evaluate interactions with neighboring points. basic equations within each grid and evaluate interactions with neighboring points.

General Circulation Model: General Circulation Model: Basic equations Basic equations

This set of equations is This set of equations is called the called the Navier-Stokes Navier-Stokes equationsequations for fluid flow, for fluid flow, which are at the heart of which are at the heart of the GCMs.the GCMs.

There are other There are other equations dealing with equations dealing with the conservation of Hthe conservation of H22O, O,

COCO22 and other chemical and other chemical

species.species.

(Conservation of monmentum)

(Conservation of mass)

(Conservation of energy)

Supercomputer power (FLOPS)Supercomputer power (FLOPS)

WorldWorld’’s Major Global Climate Modelss Major Global Climate Models

General Circulation Model: UsagesGeneral Circulation Model: Usages

Global climate projections

Global weather predictions

Global climate predictions

Required model complexityRequired model complexity

Global weather prediction (up to 1 month) - Global weather prediction (up to 1 month) - Atmospheric GCM (AGCM)Atmospheric GCM (AGCM)

Global climate prediction (beyond 1 season) Global climate prediction (beyond 1 season) - Coupled ocean-atmosphere GCM (CGCM)- Coupled ocean-atmosphere GCM (CGCM)

Global climate projections (beyond 10 years) Global climate projections (beyond 10 years) - Climate system model (CSM)- Climate system model (CSM)

Coupler .

Land Sea Ice

Atmosphere

Ocean

Framework of Climate System ModelFramework of Climate System Model

Example: Example: Land ModelLand Model

(From Bonan 2002)

Video: Climate Modeling With Video: Climate Modeling With SupercomputersSupercomputers

http://www.youtube.com/watch?v=izCoiTcsOd8http://www.youtube.com/watch?v=izCoiTcsOd8

Mesoscale modelMesoscale model

Mesoscale: 1 Km- 1000 Km, 1 min - 1 dayMesoscale: 1 Km- 1000 Km, 1 min - 1 day Grid size: 1 Km - 10 kmGrid size: 1 Km - 10 km Three characteristics: Three characteristics:

Non-hydrostatic processesNon-hydrostatic processes

Nested gridNested grid

Topography effectsTopography effects

Mesoscale model: Non-hydrostic processesMesoscale model: Non-hydrostic processes

Non-hydrostatic processes need to be consideredNon-hydrostatic processes need to be considered

Mesoscale model: Nested gridMesoscale model: Nested grid

Finer grids in regions of interestFiner grids in regions of interest

Mesoscale model: TopographyMesoscale model: Topography Topography strongly influences mesoscale processes Topography strongly influences mesoscale processes

(e.g. land breeze, mountain breeze) (e.g. land breeze, mountain breeze)

SummarySummary

General circulation models: Grid size. 3 General circulation models: Grid size. 3 usages. Name of the basic set of equations. usages. Name of the basic set of equations.

4 components of the climate system model.4 components of the climate system model. Mesoscale models: grid size. 3 characteristics.Mesoscale models: grid size. 3 characteristics.