LONG-TERM TALL TOWER CO2

MONITORING IN HUNGARYLászló HASZPRA

Hungarian Meteorological Service

Zoltán BARCZAEötvös Loránd University

Hegyhátsál is located at 46°57'N, 16°39'E, 248 m above the sea level

15OE 16OE 17OE 18OE 19OE

48ON

47ON

46ON

– 1993 weekly NOAA flask sampling at 96 m

– 1994 CO2 vertical profile measurements

(10 m, 48 m, 82 m, 115 m)

– 1997 CO2 vertical flux measurements

(eddy covariance method, 82 m)

2001 regular aircraft meas- urements over the tower up to 3000 m above ground

Early afternoon parallel in-situ measurements and flask samples (NOAA) can be used for quality control

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340 350 360 370 380 390 400 410

flask (ppm)

in-s

itu

(p

pm

)

valid data

sampling error?

extrem variabilityduring sampling

in-situ - flask = -0.062

in-situ = 0.9551*flask + 16.628

r = 0.986The slight deviation can be explained by the relatively high temporal variability, the non-perfect synchronization of the in-situ measurements and the flask sampling and by the difference in the sampling elevations

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-0.4

-0.2

0

0.2

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0.6

-30 -20 -10 0 10 20 30

lag-time (month)

corr

elat

ion

co

effi

cen

t

KPU+HHS Point Barrow Mauna Loa mbl

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360

380

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420

1980 1985 1990 1995 2000 2005

pp

m

KPU monthly averages

KPU smoothed

KPU trend

HHS monthly averages

HHS smoothed

HHS trend

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-4

-2

0

2

4

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10

12

1980 1985 1990 1995 2000 2005

pp

m/y

ear

K-puszta/Hegyhátsál SOI El Niño period

Point Barrow Mauna Loa mbl

Combined data series of the two Hungarian CO2 monitoring stationsK-puszta (KPU, 46º58'N, 19º33'E, 125 m, 1981-1999) and Hegyhátsál (HHS, 46º57'N, 16º39'E, 248 m, 1994- )

black line = marine boundary layer (mbl)

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-15

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0

5

10

15

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25

30

1994 1996 1998 2000 2002 2004 2006

pp

m

Detrended data series

Annual amplitude is decreasing (36.5 ppm → 28.7 ppm, 0.78 ppm/yr)

Change is not symmetric

0

61

122

183

244

305

366

1993

1995

1997

1999

2001

2003

2005

day

of y

ear

Hegyhátsál (spring)

Hegyhátsál (autumn)

CO2 deficit season

Changing shape of the seasonal cycle

Increase of the length of the CO2 deficit season is approx. 1 day/year

Increasing length of the growing season?

Possible reasons for the decreasing annual amplitude:

• decreasing anthropogenic emission• in Hungary and in the neighbouring countries

anthropogenic CO2 emission hardly changed between 1994 and 2004

• no sign of significant changes

• decreasing atmospheric stability, circulation

• decreasing biospheric uptake

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1992 1994 1996 1998 2000 2002 2004 2006

pp

mwinter: 1.91 ppm/yr

autumn: 1.78 ppm/yrannual: 1.85 ppm/yrspring: 1.53 ppm/yr

summer: 2.17 ppm/yr

mbl: 1.82 ppm/yr

lower than average increase in spring (Mar-May),higher than average increase in summer (Jun-Aug)

sign of earlier start of the growing season or more intensive biospheric uptake in spring

sign of decreasing summer biospheric uptake

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1996 1998 2000 2002 2004g

C/m

2 /h

March

April

May

June

July

August

slightly increasing carbon uptake in March → earlier start of the growing season

no change in April

decreasing carbon uptake from May to August

(especially in late summer[July-August])

daytime (08-16 h LST) NEE

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-50

0

50

100

NE

E (

g C

/m2

/yr)

1997 1998 1999 2000 2001 2002 2003 2004

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March

– Octo

ber

temp

erature (o

C)

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800

Mar

ch -

Oct

ob

erp

reci

pit

atio

n (

mm

)

1960-1990 average

1960-1990 average

vapour pressure deficit may give higher correlation

Haszpra et al., 2005: Long term tall tower carbon dioxide flux monitoring over an area of mixed vegetation. Agricultural and Forest Meteorology 132, 58-77.

no

me

asu

rem

en

ts

Conclusions:

• in addition to the results of other methods the changes in the temporal variation of CO2 mixing ratio and the early spring trend in the biosphere-atmosphere carbon exchange rate also indicate the earlier start of the growing season

• the gradually drier and warmer than average weather in the growing season resulted in decreasing biospheric carbon uptake between the late 90’s and 2003, turning the region to net carbon source by 2003

• this climate anomaly period seemed to be interrupted in the influence region of the station in 2004, and the region acted again as a net carbon sink

• the measurements give the experimental evidence that the expected drier and warmer future climate may turn the region into a significant net natural carbon source