Tools for quantifying GHG Tools for quantifying GHG emissions from Agroecosystems emissions from Agroecosystems E. Pattey, R.L. Desjardins and W. Smith Agriculture and Agri-Food Canada, Research Branch, Ottawa CAgM Expert Team Meeting on the Contribution of Agriculture to the State of Climate Ottawa, Canada, 27 - 30 September 2004
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Tools for quantifying GHG emissions from Agroecosystems
Tools for quantifying GHG emissions from Agroecosystems. E. Pattey, R.L. Desjardins and W. Smith. Agriculture and Agri-Food Canada, Research Branch, Ottawa. CAgM Expert Team Meeting on the Contribution of Agriculture to the State of Climate Ottawa, Canada, 27 - 30 September 2004. - PowerPoint PPT Presentation
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Tools for quantifying GHG emissions Tools for quantifying GHG emissions from Agroecosystemsfrom Agroecosystems
E. Pattey, R.L. Desjardins and W. Smith
Agriculture and Agri-Food Canada, Research Branch, Ottawa
CAgM Expert Team Meeting on the Contribution of Agriculture to the State of Climate
Ottawa, Canada, 27 - 30 September 2004
INTRODUCTIONINTRODUCTION
Goals:
Develop a set of reliable Models for estimating net GHG emissions from agricultural sources/sinks and for deriving emissions factors relevant of a given country situation.
Establish a series of databases of the various agricultural activities for integrating the GHG emissions over space and time domains (land use, mgt practices, animal production, climate…) .
INTRODUCTION (Cont’d)INTRODUCTION (Cont’d)
A “reliable” Model is:sensitive to input conditions such as management practices;adapted to the geographical and climatic conditions under which it will be used;based on sound scientific knowledge.…Ideally it requires a set of input descriptors easily available.
Framework:
Any national GHG emission accounting system needs to be transparent (well-documented), verifiable (pilot test sites, scaling-up experiments etc.) and consistent with the Kyoto Protocol.
OUTLINEOUTLINE
•Speaker more familiar with Canadian situation Example of Canada…
•GHG emission estimates from agricultural sources in Canada, CO2, CH4, N2O
•Tools for developing models (chamber, tower)
•Tools for verifying temporal dynamic and top-down constraints (tower, aircraft)
•Results from tower- aircraft-based measuring systems
•Modeling results from Ecosys, DNDC and Daycent
•Summary
Greenhouse Gas Emissions from Greenhouse Gas Emissions from Canada’s Agroecosystems Canada’s Agroecosystems
(100 Year Time Horizon - Tg of CO(100 Year Time Horizon - Tg of CO22 equivalents) equivalents)
CO2 8 7 5 2CH4 22 19 20 23N2O 27 30 28 38
1981 1986 1991 1996 2001 02440
Total 57 56 53 63 64
GHG flux measuring techniques only cover a limited portion GHG flux measuring techniques only cover a limited portion of the space and time domainsof the space and time domains
Aircraft
Atmospheric Inversion
Tower
Chamber
1 102 105 104 103
1
103
104
102
10
Area m2
Time h
Soil Cores
Mass Balance
10 107 106
BLS&
Tracer
109 108
Regional and sub-continental estimates using tall towers and
CBL budgets
Satellite
Aud
iting
/ Mon
itori
ng
Long Term Experimental Sites: Flux, Meteorological and Ancillary
Developing new knowledge Developing new knowledge on mgt practiceson mgt practices
Fg = dC V Mw
dt A Mv
Non-Flow Through, Non-Steady State Non-Flow Through, Non-Steady State Chamber MeasurementsChamber Measurements
Experimental design for comparing management practices and environmental conditions
Tower-based MeasurementsTower-based Measurements
Closed-path Tunable Diode Laser
Air Intakes
zKF g
g
Sonic anemometer
Setup for quantifying NSetup for quantifying N22O fluxes for two management practicesO fluxes for two management practices
1 TDL connected to 2 micromet. towers
145 150 155 160 165 170 175 180 185 1900.0
0.5
1.0
1.5
2.0
2.5
Fig. 4
15.5 g N m -2
9.9 g N m -2
N 2O F
lux
(mg
N m
-2 h
-1)
Day of Year
ECOSYS
Grant, R. and Pattey, E., 2003. Modelling variability in N2O emissions from fertilized agricultural fields. Soil Biology and Biochemistry:35(2): 225-243.
Urea applied at the following rates:0.218 0.2540.120 0.120
Meas. model
Non-linear increase of N2O emissions with fertilizer application rate
Flux Towers are the only suitable measuring approach …Flux Towers are the only suitable measuring approach …during Snow meltduring Snow melt ( (Permanent Site, Ottawa)Permanent Site, Ottawa)
Harvested corn field - Snow meltHarvested corn field - Snow melt
The global Fluxnetglobal Fluxnet project features towers tracking the movement of carbon dioxide between various ecosystems and the air with emphasis on forest
Ameriflux
Euroflux
Japanflux
Establish a network of towers for measuring N2O fluxes to verify temporal dynamics of models and assist in scaling up from individual agricultural fields to region
Biocap
Aircraft-Based Measurements
The REA sampling system and TDL Laser
Vent (Dead band)
PTFESample Bag
DC Power supply
3-wayValve
Mass-FlowController
2-mFilter
Reliefvalve
DiaphragmPump 12 l/min
Inlet
UP
DOWN
¼” PTFEtubing
Aircraft REA system
LaboratoryTDL Laser
Canada
Casselman Flight Track
Morewood Flight Track
0 5 10 15 km
Tower Site
AC/Tower Study Sites, Spring 2001, 2003 and 2004
Casselman Flight Track
12 km
13km
Casselman
Highway 417
N
soy
cereals
pasture/grass
alfalfa
forest
corn
town
LEGEND
Morewood Flight Track
N
Mean Crop Cover in 2000 within Footprint of Aircraft Transects
Estimated Direct N2O-N Emissions from Agriculture Soils in Canada Using DNDC
(1970-1999)
“Model”
province
region
SLC polygon
“Situations” defined by:
• Soil• Climate• Land use• Management
National C and GHG Accounting and National C and GHG Accounting and Verification SystemVerification System
country
SOC & GHGEmissions for each“situation”
Verification by direct measurement of national GHG Verification by direct measurement of national GHG estimates best done through holistic top-down estimates best done through holistic top-down national, continental, or global scale GHG budgetsnational, continental, or global scale GHG budgets
N2O emissions?
Scientific uncertaintyScientific uncertainty
CH4 N2O
GH
G e
mis
sion
(M
t CO
2 eq
uiv.
per
yea
r)
-40
-20
0
20
40
60
80
CO2
Relativeuncertainty(estimated)
Scientific uncertaintyScientific uncertaintyUn
certa
inty
Uncerta
inty
UnderstandingUnderstanding00
Tools to quantify uncertainties
•Sensitivity tests of models
•Monte-Carlo approach for evaluating uncertainty
Summary
•Tools for measuring GHG fluxes only cover a limited portion of the space and time domains
•The combination of tower and aircraft-based GHG flux measurements provide valuable information to estimate regional fluxes on a daily basis
•Models are essential for deriving national estimates of GHG emissions
•Models still require lots of verification and improvement to provide more accurate estimates