weather, climate and ecosystems 111 climate system.pdfrainfall) espm 111 ecosystem ecology. 3...

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ESPM 111 Ecosystem Ecology

Weather, Climate and Ecosystems

Dennis BaldocchiUniversity of California, Berkeley

2/1/2013


Weather, Climate and Ecosystems: Outline

• Concepts– Atmospheric Meteors and Composition– ‘Greenhouse-Effect’ Principles– Seasons– Global and Regional Circulation

• Climate– Climate Forcing and Variability– Global Temperature, Precipitation and Radiation

Maps

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Weather and Climate Meteors

• Electromagnetic Radiation– Solar (shortwave) and Terrestrial (longwave)– f(season, clouds)

• Temperature– Air, soil, vegetation

• Wind Velocity and Direction• Moisture

– Gaseous: vapor pressure, Relative Humidity, dew point

– Liquid: Rain, dew, clouds– Solid: snow, sleet, frost, hail, rime, clouds

• Pressure

Many Ecological Processes are a Function of, or Correlate with, Climate and Weather

• Photosynthesis = f(sunlight, temperature, humidity, rainfall)

• Evaporation = f(sunlight, temperature, humidity, rainfall)

• Respiration = f(temperature, rainfall)

• Decomposition =f(temperature, rainfall)

• Ecosystem Structure and Function = f(sunlight, temperature, rainfall)

• Soil Formation and Nutrition= f(temperature, rainfall)


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Weather vs Climate

• Weather is the Recent Condition of the Atmosphere, yesterday, today, tomorrow– Weather is Chaotic, can Exhibit Extreme

Behavior

• Climate is the Average Condition of the Atmosphere over long-time durations, e.g. 30 years, Century, Millennium– Climate is relatively stable, e.g. summers are

hot, winters are coldESPM 111 Ecosystem Ecology


Weather/Climate Concepts• Atmosphere is a Dynamic and Complex System

– Multiple Positive and Negative Feedbacks that operate across a Spectrum of Time and Space Scales

– Non-Linear Processes– Sensitivity to Initial Conditions– Experiences Strange Attractors, so is Phase Space is

Constrained– Thresholds and Tipping Points

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Chemistry and Physics of the Atmosphere


Atmospheric Composition

• Nitrogen– 78.084%

• Oxygen– 20.946%

• Argon– 0.934%

• Carbon Dioxide– 0.0395%

• Water Vapor– 0.1 to 4%

• Trace Gases– Nitrous Oxide, CO, Methane, Ozone, VOCs

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Partial Pressure Law

• Total Pressure is the sum of the partial pressures of its components– P=pn2+po2+par+ph2o+pco2+…

• P at sea level, 101.3 kPa

• P equal mass of overhead atmosphere time acceleration due to gravity, per unit area

AP M g


Atmospheric Temperature Profile

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Solar Constant

• 1366 J m-2 s-1 or W m-2

• Amount of Energy Available to Drive Work by the Climate System and Life


Planck's Law

Wavelength, m

1e-8 1e-7 1e-6 1e-5 1e-4 1e-3

Ene

rgy

(T,

)

1e+3

1e+4

1e+5

1e+6

1e+7

1e+8

1e+9

1e+10

1e+11

1e+12

1e+13

1e+14

1e+15

Sun, T = 5800 KEarth, T = 298 K

Comparison between Planck’s Law for Sun and Earth

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Wavelength (microns)

1 10 100

Ab

sorp

tion

Cro

ss-S

ect

ion

(cm

-1/(

mol

ecu

le c

m-2

)

1e-21

1e-20

1e-19

1e-18

1e-17

H2O

CO2

HI-Tran Database

Many Atmospheric Trace Gases Absorb & Re-emit Infrared Radiation


www.GlobalwarmingArt.com

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ESPM 111 Ecosystem Ecologywww.GlobalwarmingArt.com


Trenberth et al 2009 BAMS

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Basic Earth/Sun Geometry

Lutgens/Tarbuck, Atmosphere

Zachos et al Science 2002

Natural Solar Forcing of Climate Variability Over Geological Time

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Source Rob Rohde, http://www.globalwarmingart.com/images/7/7e/Milankovitch_Variations.png

Natural Forcing of the Climate System, last Million Years

Timing of Ice Ages

• MilankovitchTheory states Glaciers form when solar intensity is weak during summer of northern latitudes, as when Earth is less tilted with orbital plane (e.g. Obliquity with 41 ky cycles)

• Isotope show ice-ages grow and wane with 41 ky cycle for Early Pleistocene (1-3 Million yBP) and 100ky cycle in late Pleistocene (0-1 Million yBP)– Eccentricity of Earth’s orbit with 100 ky cycle has a weak forcing on

summer insolation

• The integral of solar radiation (time x intensity), not peak irradiance, controls 41 ky timing of ice age of the Early Pleistocene (1 to 3 million ybp)– This corresponds with Obliquity, which has 41 ky cycle instead of 100 ky

with Eccentricity because Summers are shorter when Earth is closer to Sun and Radiation is greatest


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Lapse Rates, Temperature Decreases with Height

• Dry Adiabatic Lapse Rate– 9.8 C km-1

• Moist Adiabatic Lapse Rate– 6 C km-1

Change in Internal Energy Equals Change in Work Done on the Air Parcel


Adiabatic Lapse Rate, Lifted Condensation Level and Clouds

http://www.sci.uidaho.edu/scripter/geog100/lect/05-atmos-water-wx

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He

igh

t,m

z

T

unstablethermal

stratifiation

He

igh

t,m

stablethermal

stratification

z

THe

igh

t,m

near neutralstability

z

T

Tparcel > Tair

Tparcel < Tair

Concepts of Thermal Stratification

Temperature


Orographic PrecipitationAir Lifted by a Mountain, Cools, Can

Condense, Form Clouds and Rain/Snow

http://www.sci.uidaho.edu/scripter/geog100/lect/05-atmos-water-wx

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Succession of Weather Fronts off the Pacific Coast of North AmericaRole of High and Low Pressure Zones on Weather


LOW

High

Cyclonic CirculationAir is Convergent

Anti-Cyclonic Circulation:Air is Divergent

High and Low Pressure Systems in Northern Hemisphere

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Convergence:Air Rises, Temperature Decreases,Vapor Condenses, Clouds Form,Rain Possible

LOW


Divergence:Air Sinks, Temperature WarmsCloud Formation is Suppressed

High

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http://www.worsleyschool.net/science/files/aboutweather/coldfront.gif

Cold and Warm Fronts and RainTwo Ways to Lift Parcels of Air, Form Clouds and Rain


Large Scale Patterns Dominating Weather in California

Aleutian Low Steer Storm Tracks during Winter

North Pacific High Block Storms duringSummer

http://www.pacificstormsclimatology.org/index.php?page=regional-overview

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Weltzin et al 2003 Bioscience

Rainfall Periodicity and Scale


Differential Solar heating causes Air to rises at equator and subsided at poles

This is superimposed upon the Earth’s rotation and the Coriolis Force which determineswind direction

Circulation cells help explain global distribution of rainfall

From Chapin

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La Nina


El Nino

http://weatherevents.co.uk/widespread-flooding-in-australia-and-the-affect-of-la-nina/

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Climate Distribution

ESPM 111 Ecosystem EcologyIPCC dataset

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ESPM 111 Ecosystem EcologyIPCC dataset


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Summary

• Solar Energy Drives Weather and Climate• Trace Gases that absorb and re-radiate energy

warm the atmosphere and Earth’s surface above its radiative equilibrium value

• Differential heating of the Earth and its Rotation causes circulation of the air

• Different declination, relative to the Sun, causes the seasons.

Discussion PointsNext Ice Age?

• Would Occur within next 1500 Years if CO2 did not rise above 280 ppm?

• Will Future Generations Hate or Thank Us– With 7+ Billion People Living on Earth what

would happen if we did not stave off the Next Ice Age?

– Is our Fossil Fuel Emissions a form of GeoEngineering to Prevent the Next Ice age?

• Tzedakis et al. 2012 Nature GeoscienceESPM 111 Ecosystem Ecology

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