1

Lecture Lecture 17 17

The dashed land-use change line does not include management-climate interactions

The land sink was a source in 1987 and 1998 (1997 visible as an emission)Source: Le Quéré et al. 2012; Global Carbon Project 2012

Carbon Cycle Diagram

Carbon in Atmosphere

Plants use carbon to make food

Animals eat plants and

take in carbon

Plants and animals die

Decomposers break down dead things,

releasing carbon to

atmosphere andsoil

Bodies not decomposed —

after many years, become part of oil or coal deposits

Fossil fuels are burned; carbon is

returned to atmosphere

Carbon slowly released from

these substances returns to

atmosphere

6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2

PhotosynthesisPhotosynthesis

Using light converts carbon and water into sugars

Autotrophic respiration (plants respiration)

Heterotrophic respiration (soil respiration)

RespirationRespirationOrganic matter is converted back into CO2

Atmosphere

Biosphere

Photosynthesis

Respiration

The ecosystem acts as The ecosystem acts as A Carbon SinkA Carbon Sink

Atmosphere

Biosphere

Photosynthesis

Respiration

The ecosystem acts as The ecosystem acts as A Carbon SourceA Carbon Source

Eddy Flux TowerEddy Flux Tower

COCO22

HH22OO

CHCH44 T T

COCO22

HH22OO

CHCH44 T T

COCO22

HH22OO

CHCH44 T T

Ecosystem-Atmosphere Ecosystem-Atmosphere ExchangesExchangesEddy flux towers in the Rocky Mountains of ColoradoEddy flux towers in the Rocky Mountains of Colorado

Tower-1

Tower-2

(a) (b)

(c)

Acknowledgements to

Supports from NSF AGS under Grant No. 0930015,Queens College Research Enhance Award (90935-0102), many people from CUNY and Black Rock Forest

1.1. Turbulent fluxTurbulent flux

2.2. Eddy-covariance techniqueEddy-covariance technique

TurbulenceTurbulence

No regular No regular patternpattern

What we will learn todayWhat we will learn today

FluxFlux Flux is defined as Flux is defined as the amount that the amount that flows through a flows through a unit area per unit unit area per unit time.time.

areatime

energyor mass

ImportantImportant

DifficultDifficult

COCO22 turbulent flux turbulent flux Eddy CovarianceEddy Covariance

w c

Eddy Covariance Turbulent Eddy Covariance Turbulent FluxFlux w c

Sonic AnemometerSonic Anemometer

w

Infrared gas analyzer

c

w w w Vertical Vertical velocityvelocity

flu

ctu

ati

on

flu

ctu

ati

on

velo

cit

yvelo

cit

y

mean

valu

em

ean

valu

e(3

0-m

in.)

(30-m

in.)

10/s*1800s=18,000/30min.10/s*1800s=18,000/30min.

COCO22 c c c

flu

ctu

ati

on

flu

ctu

ati

on

CO

2C

O2

mean

valu

em

ean

valu

e(3

0-m

in.)

(30-m

in.)

1 1 2 2 18000 18000...18000

w c w c w cw c

P3=10kgP3=10kgP1=20kgP1=20kg P2=30kgP2=30kg

FluctuationFluctuation

++

33 = 20P kg

Question:Question:

If the biggest one moves in If the biggest one moves in the group, is his weight the group, is his weight fluctuation positive or fluctuation positive or negative?negative?

P’>0P’>0

FluctuationFluctuation

P’>0P’>0

O Mean air temperature over a desert 50 T C

O20T C O20 T C Question:Question:

Is the temperature fluctuation Is the temperature fluctuation of the parcel of cool air of the parcel of cool air positive or negative?positive or negative?

0 T

COCO

22

w c =Respiration>0

w c Night

c

ZZ ( )c z

wc

>0

wc