EC FLUXES: BASIC CONCEPTS AND BACKGROUND. Timo Vesala (thanks to e.g. Samuli Launiainen and Ivan Mammarella)

Transcription

1 EC FLUXES: BASIC CONCEPTS AND BACKGROUND Timo Vesala (thanks to e.g. Samuli Launiainen and Ivan Mammarella)

2 Scales of meteorological processes: Synoptic scale, ~ 1000 km (weather predictions, 3-7days) Mesoscale, ~ 100 km (land-sea breeze, hours a day) Microscale, ~ 1 mm 1 km; ~ hour or less

3 1. Big issues and motivation trial 2. Concept of flux 3. C and water cycles and flux towers 4. Methane and wetlands 5. Lakes 6. Urban surface 7. N and reactive gases 8. ICOS (Integrated Carbon Observation System) and Versatile field stations

4 Fate of Anthropogenic CO 2 Emissions (2010) 9.1±0.5 PgC y ±0.2 PgC y -1 50% 2.6±1.0 PgC + y-1 0.9±0.7 PgC y 26% -1 Calculated as the residual of all other flux components 24% 2.4±0.5 PgC y -1 Average of 5 models Global Carbon Project 2010; Updated from Le Quéré et al. 2009, Nature Geoscience; Canadell et al. 2007, PNAS

5 Science 320, 1444 (2008) Physical, chemical and biological processes affect the climate (energy, hydrology and atmospheric composition) Complex and non-linear interactions can damp and enhance anthropogenic changes Forests act as carbon sinks and feedbacks can increase or decrease this climate forcing Transpiration of tropical forests cools and the darkness of boreal forests (albedo) warms Net effects are not known

6 CONCEPT OF FLUX

7 MASS TRANSPORT BETWEEN THE ATMOSPHERE AND ECOSYSTEMS Material produced or absorbed by the biological sink is either stored in the air or transported away Transport by Turbulence (eddies) Advection (bulk flow)

8 What is a vertical flux? Vertical flux (density!) is defined as the amount of material transported vertically per unit area per unit time Typical units: mmol m -2 s -1 CO 2, plant physiologists mg m -2 s -1 pollution community mg m -2 hr -1 chambers, VOC ppb m s -1 chemists units # cm -2 s -1 particle number fluxes meq m -2 s -1 comparisons, acidity kg ha -1 yr -1 or g m -2 yr -1 W m -2 annual budgets CO 2, N sensible and latent heat fluxes E. Nemitz

9 C and WATER CYCLES and FLUX TOWERS

10 Evapotranspiration = Evaporation + transpiration

11 Heterotrophic respiartion Net ecosystem exchange (NEE) = - (growth decomposition) = - NEP Photosynthesis (assimilation) Growth Decomposition

12 Forest site Hyytiälä TER=NEE 12 Kolari et al. 2009

13 Hyytiälä energy fluxes EC Launiainen et al

14 Lompolojänkkä/Pallas Northern boreal fen Kenttärova/Pallas Spruce forest Peat soil Long-term flux sites in Finland Mineral soil Urban environment Siikaneva/Hyytiälä Southern boreal fen Kaamanen Subarctic fen Hyytiälä Scots pine (SMEAR II) Lammi Lake Kumpula Urban (SMEAR III) Loppi Drained pine forest Sodankylä Scots pine

15

16

17 Weekly average NEE, pine forest, Hyytiälä S. Launiainen

18 Intro Soil & Earth System Interact & feedback Lateral BGC Global Earth Obs. & MDI Global evapotranspiration (ET): ca. 65 Eg yr -1 Crossvalidation Indep. validation Jung et al., Nature MM. Reichstein

19 METHANE and WETLANDS

20 Methane (CH 4 ) Siikaneva fen, Hyytiälä satellite site, Southern Finland

21 CO 2 CO 2 CO 2 CH 4 moss layer aerobic zone org-c water level CH 4 anaerobic zone T. Riutta

22 CO 2 CO 2 CH 4 CO 2 CO 2 CH 4 moss layer aerobic zone org-c water level CH 4 org-c anaerobic zone

23 CO 2 CO 2 CH 4 CO 2 CO 2 CH 4 moss layer aerobic zone org-c water level CH 4 org-c anaerobic zone

24 Methane production and oxidation (Diffusive) transport in peat and plants Bubble formation (heterogeneous nucleation?) and release to the atmosphere

25 Carbon balance (x -1!) of Siikaneva fen g m -2 a -1 gc m -2 a -1 CO CH Total C 42 J. Rinne

26 LAKES

27 Lake Valkea-Kotinen, Southern Finland A. Ojala

28 Time series on CO 2 fluxes in Valkea-Kotinen Annual flux: 77 (±11) g C m -2 yr -1 This is almost 30 times higher than the long-term (postglacial) carbon accumulation rate of 2.8 g m -2 yr -1 J. Huotari, GRL

29 Boreal Lake Valkea-Kotinen, Finland (Nordbo et al., 2011; Huotari et al., 2011) Sensible and latent heat fluxes CO 2 fluxes (this lake is net source of CO2)

30

31 URBAN SURFACE

32 SMEAR III Helsinki, urban site EC CO2 flux diurnal variation for different seasons and wind sectors 32 Järvi et al. 2008

33 CO2 flux and traffic density in Kumpula Campus

34 Comparison of 3 different surfaces Average diurnal courses in June 2009

35 N

36 Nitrogen balance in Hyytiälä DEPOSITION 5 Dry 0.5 Wet 4.5 NH 4 -N 1.4 NO 3 + NO 2 -N 2 DON 2 THROUGHFALL 2.6 Mineral N 1 DON 1.5 Stemflow Litter fall 26 Nitrogen N IN VEGETATION 200 Foliage 80 Wood 70 Bark 50 Roots 20 Retranslocation Gas exchange with atmosphere -2 to Gases N 2 N 2 O NO NO 2 Denitrification N-fixation 0.5 to 2.5 NO 3 -N 0.1 Nitrification NH 4 -N 1 Plant uptake 23 Runoff and leaching 0.5 Proteins 700 Amino acids Solids and liquids Humus 1300 Microbes 46 M. Pihlatie Processes [kg ha -1 a -1 ] Strong Input Plant uptake Weak Output Pools [kg ha -1 ]

37 Published in Nature.although everybody knows. Mangani et al.

38 From canopy emission to above canopy fluxes Stochastic Lagrangian transport model with simple chemistry (SLTC) Chemistry Simple first-order chemical degradation flux Chemistry emission Chemistry Chemistry J. Rinne

39 ICOS (Integrated Carbon Observation System)

40 Monitoring of GHG concentrations and fluxes Tentative ending date 2031.

41 FLUXNET is probably the largest geophysical experiment in Earth and the application and potential information contained in the collected data goes beyond the individual sites. D. Papale Astrophysicists have Hubble, nuclear physicists have CERN, biogeochemists have FLUXNET. a reviewer of Nature paper (Valentini et al., 2000)

42 SMEAR II = Hyytiälä