Carbon Cycle Introduction

Size: px

Start display at page:

Download "Carbon Cycle Introduction"

Erica Waters
6 years ago
Views:

1 Carbon Cycle Introduction Inez Fung UC Berkeley 2nd NCAR-MSRI Summer Graduate Workshop on Carbon Data Assimilation NCAR July

2 High-precision Atm CO 2: at MLO since ppmv Last Glacial Maximum 280 ppmv in the preindustrial (~1800AD) 380 ppmv in 2005

3 Units 3 3 C( kgc / m ) = ( kgair / m ) X( molec / moleair ) ( MWt / MWt ) MWt = 12gm / mole; MWt = 29gm / mole C air C air 14 2 Area = dxdydz = 5 10 ( m ) 100Pmb 2 18 MassAtm = dxdydz = ( kgair / m ) Area ~ 5 10 kgair g 6 MassC( 300 ppmv ) = MassAtm ( 300 x10 ) ( 12 ) ~ kg = 600 PgC = 600GtC 1PgC 0.5 ppmv( mixed _entireatm )

Outstanding Questions Only half of the CO 2 produced by human activities is remaining in the atmosphere Where are the sinks that are absorbing over 40% of the CO 2

4 Outstanding Questions Only half of the CO 2 produced by human activities is remaining in the atmosphere Where are the sinks that are absorbing over 40% of the CO 2 that we emit? Land or ocean? Eurasia/North America? Why does CO 2 buildup vary dramatically with nearly uniform emissions? How will CO 2 sinks respond to climate change?

Continuous Carbon Cycling Fluxes PgC/yr Inventory PgC Turnover time = Inventory/Flux Atm CO2 --> inventory Land: turnover time 10 1-10 2 yrs.

5 Continuous Carbon Cycling Fluxes PgC/yr Inventory PgC Turnover time = Inventory/Flux Atm CO2 --> inventory Land: turnover time yrs. Ocean: turnover time yrs Difficult (time consuming and expensive) to measure changes in land and ocean inventories. Focus on fluxes

6 Conservation of Carbon in Atm C t + { ( C ) = S + { z= 0 Atm _transport+ mixing SourcesSinks { P Chem Prod S = F F + LandUs e + (Foa F ao ) + (Fb a F a b ) Separate out background (pre-industrial) from the perturbation (last 200 years) carbon cycle: Pre-industrial: C = C + C' ( C ) = (F F ) + (F F ) oa ao ba ab

7 Conservation of Perturbation Carbon in Atm C t + { ( C ) = S + { z= 0 Atm _transport+ mixing SourcesSinks { P Chem Prod S = F F + LandUs e + (Foa F ao ) + (Fb a F a b ) In later lectures, the conservations equation may appear as: Kalnay: Nychka: T(t b i+ 1 ) = M[T(t a i )] x (x ) G( u ) i+ 1 = i +

8 Conservation of Perturbation Carbon in Atm C t + { ( C ) = S + { z= 0 Atm _transport+ mixing SourcesSinks { P Chem Prod S = F F + LandUs e + (Foa F ao ) + (Fb a F a b )

9 Fossil Fuel Emission >95% emission in Northern Hemisphere

10 Atm CO2 Signature of Fossil Fuel Emission: N-S gradient

11 Conservation of Perturbation Carbon in Atm C t + { ( C ) = S + { z= 0 Atm _transport+ mixing SourcesSinks { P Chem Prod S = F F + LandUs e + (Foa F ao ) + (Fb a F a b )

12 Terrestrial Carbon Cycle Growth, mortality, decay GPP: Gross Primary Productivity (climate, CO 2, soil H 2 O, resource limitation) Ra: Autotrophic respiration (T, live mass, ) Rh: Heterotrophic respiration: Decay (T, soil H 2 O,..) NPP=GPP-Ra GPP Ra Rh 120 PgC/yr PgC 1200 PgC

13 Deforestation Tough to estimate deforested area Carbon inventory before deforestation Fate of removed carbon Fate of litter and soil carbon Tough to discriminate atm CO2 signature

14 Veg Type(x,y) annual mean NPP(x,y)

15 NDVI-seasonal Satellite Greenness index: NDVI Seasonality of NPP August 2000 Seasonality of Respiration not well-defined Net flux not well-defined at every location February 2001

16 Impact on Atmospheric CO Photosynthesis Seasonal asynchrony between photosynthesis and decomposition CO 2 Flux Jan From Atm Respiration To Atm Dec net fluxes of CO 2 to and from atm seasonal cycle of CO 2 in atm Annual imbalance carbon source/sink

17 Atmospheric CO 2 Signature of Ecosystem C Exchange: Seasonal Cycle Mauna Loa, Hawaii Pt. Barrow, Alaska 6.5 ppmv 16 ppmv Source: NOAA/CMDL Amplitude of atmospheric CO 2 seasonal cycle increases poleward: telecoping of growing season and greater asynchroneity bet fluxes Growing season net flux ~15-20% of annual NPP

18 Conservation of Perturbation Carbon in Atm C t + { ( C ) = S + { z= 0 Atm _transport+ mixing SourcesSinks { P Chem Prod S = F F + LandUs e + (Foa F ao ) + (Fb a F a b )

$remineralizatio n depth DIC, NO3 Foa F ao = k { ( CO2* sfc _ocn { pco2atm _sfc ) 1 42443 GasExchRate( m / s ) mole C / m3$

19 Ocean C from the Atm s Perspective: atm photosyn CO Pg C/yr DIC = CO 2 * + HCO CO 3 = 1-2 % 80-90% remineralizatio n depth DIC, NO3 Foa F ao = k { ( CO2* sfc _ocn { pco2atm _sfc ) GasExchRate( m / s ) mole C / m3 solubility( T )

20 Marine Productivity Is possible when upwelling brings: Nutrients from below to euphotic zone Cold water Small Flux, small inventory of organic C But alters DIC(z)

JGOFS/WOCE global survey (1980s and 1990s) -Global baseline (hydrography, transient tracers, nutrients, carbonate system) -Improved analytical techniques

21 JGOFS/WOCE global survey (1980s and 1990s) -Global baseline (hydrography, transient tracers, nutrients, carbonate system) -Improved analytical techniques for inorganic carbon and alkalinity (±1-3 μmol/kg or 0.05 to 0.15%) -Certified Reference Materials -Data management, quality control, & public data access

Ocn currents ~ cm/s Time scale ~ 10 3 yr Atlantic Pacific Depth

22 OceanC : Mainly Dissolved Inorganic Carbon (DIC) Conveyor Belt Transport of DIC: Southward in Atlantic Northward in Pacific Ocn currents ~ cm/s Time scale ~ 10 3 yr Atlantic Pacific Depth Biology and DIC: Depletion near sfc Enrichment at Depth Latitude N

$Air-Sea Fluxes of CO2 F = F F ocn oa ao = k { ( CO2* sfc _ocn {$

24 Air-Sea Fluxes of CO2 F = F F ocn oa ao = k { ( CO2* sfc _ocn { pco2 atm _sfc ) GasExchRate( m / s ) molec / m3 solubility( T )

25 S C t SUMMARY + { (C ) = S { z = 0 Atm _transport+ mixing SourcesSinks = FF + LandUse + (F F ) + ( F F FF: mainly NH, relatively aseasonal oa ao ba ab LandUse: mainly source tropics, sink in mid-latitudes Ocean: outgassing in equatorial oceans, absorption at mid-hi latitudes (in summer. Not sure about winter) Vegetation and soils: annual mean fluxes~0 locally, fluxes have large diurnal (~100 ppmv) and seasonal ranges (~30 ppmv) )

26 Atm CO2 data for assimilation

m; Continuous Aircraft data Very few obs over land (CO2 very variable)

27 Atm CO2 Observations Mauna Loa, Hawaii In situ: tower, continuous Flask: 2m, twice weekly, ~10 2 locations >400m Tall Tower: 11, 30, 76, 122, 244 and 396 m; Continuous Aircraft data Very few obs over land (CO2 very variable) Upcoming: satellite data, column, (10 6 locations twice weekly) WLEF, Park Falls, Wisconsin

28 In-situ Atmospheric Observing Network Discrete surface flasks (~weekly) Continuous surface (hourly) observatories Tall towers continuous (hourly) Aircraft profiles (~weekly)

29 Global Distribution of CO2 in the lower troposphere secular trend N-S gradient Seasonal cycle Interannual variations

30 CCSM Climate Working Group Board of Trustees Reception ASP Reviews National Science Board Breakfast CO 2 Concentration in the Outer Damon Room, NCAR Mesa Lab, 2/7 2/9/06

31 Surface Observatories Where both insitu (hourly) and flask (biweekly) data are taken: Diurnal and weather cycles on top of seasonal cycles

32 Seasonal CO 2 : Continental vs Oceanic Sites CO 2 seasonal cycle attenuate, but still coherent, far away from source/sink region Peak-trough amplitude of seasonal cycle ~ 30 ppmv (~10%)

33 Diurnal CO 2: Highly variable in boundary layer WLEF Tall Tower, Park Falls, WI m Column Integral 11 m 30 m 76 m 122 m 244 m 396 m Calm night: stably stratified boundary layer Well-mixed PBL Diurnal cycle of photosynthesis and respiration (Peter Bakwin, CMDL, 2001) > 60 ppmv (20%) diurnal cycle near surface Varying heights of the planetary boundary layer (varying mixing volumes)

34 Vertical Profiles (free troposphere) DATE 2006

35 COBRA 2000 Aircraft Campaigns

36 Surface Fluxes => Atmospheric CO2

5 km IFOV 10 pixel wide swath 105 minute polar orbit

37 Orbiting Carbon Observatory (Planned Dec 2008 launch) Estimated accuracy for single column ~1.6 ppmv 1 x 1.5 km IFOV 10 pixel wide swath 105 minute polar orbit 26º spacing in longitude between swaths 16-day return time

38 Century Multiple Time/Space Scales g GCM Carbon 1-D BGC Decade Satellite GPP, NPP TIME Year Tower Flux Orbiting Carbon Observatory Tower Footprint Atmospheric Inversion Day Hour Aircraft Flux Plot Tower Landscape Region Continent Globe SPACE

Carbon Cycle: An Inverse Problem. Inez Fung

Carbon Cycle: An Inverse Problem Inez Fung Outstanding Questions Only half of the CO 2 produced by human activities is remaining in the atmosphere Where are the sinks that are absorbing over 40% of the