methane and nitrous oxide in north america: using an lpdm to constrain emissions eric kort...
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Methane and Nitrous Methane and Nitrous OxideOxide
in North America: Using in North America: Using an LPDM to Constrain an LPDM to Constrain
EmissionsEmissions
Eric KortEric [email protected]@fas.harvard
.edu.eduNon-CO2 Non-CO2 WorkshopWorkshop
October 23, 2008October 23, 2008
ApproachApproach Atmospheric Atmospheric MeasurementsMeasurements
Use Use receptor receptor orientedoriented framework framework (STILT) to link (STILT) to link measurements with measurements with emissionsemissions
Forward Model Forward Model Concentrations, Concentrations, Optimizations, InversionsOptimizations, InversionsSTILT developed by John Lin and
Christoph Gerbig
TrajectoriesTrajectories Receptor Points- Locations in space-Receptor Points- Locations in space-
time where measurements are madetime where measurements are made Release an ensemble of ‘particles’, Release an ensemble of ‘particles’,
which travel backwards in time, which travel backwards in time, stochastically sampling the turbulencestochastically sampling the turbulence
Driving wind fields Driving wind fields are of crucial are of crucial importance: importance: i.e. mass conservationi.e. mass conservation
TrajectoriesTrajectories Meteorological Driver: WRF v2.2Meteorological Driver: WRF v2.2
Use time-averaged mass fluxes- ensures Use time-averaged mass fluxes- ensures good mass conservationgood mass conservation
Uses analysis nudging to increase realismUses analysis nudging to increase realism Turbulence includedTurbulence included
Release 500 particles backwards 10 Release 500 particles backwards 10 days in time from each receptordays in time from each receptor Case study used 100 particles 6 days backCase study used 100 particles 6 days back
Using STILT, comparison w/ FLEXPART underway…, preliminary results encouraging, wind fields dominate answer, choice of LPDM does not strongly bias footprints
Go to Thomas SlidesGo to Thomas Slides
TrajectorTrajectoriesiestoto
FootprintFootprint
FootprintFootprint
Critical Item which links Critical Item which links measurements to emissions (Unit: measurements to emissions (Unit: ppb/flux)ppb/flux)
With this calculated can:With this calculated can: Interface w/ prior emissions field- bottom-Interface w/ prior emissions field- bottom-
up model concentrationsup model concentrations Follow this with simple scalar optimizationFollow this with simple scalar optimization Or Perform a Bayesian optimizationOr Perform a Bayesian optimization
Or go straight to a Geostatistical InversionOr go straight to a Geostatistical Inversion
Footprint * Footprint * Prior Prior
Emission Emission FieldField
Result = Enhancement of gas at measurement point due to source
*
Prior Emissions FieldsPrior Emissions Fields MethaneMethane
Anthropogenic- Anthropogenic- EDGAR32FT2000EDGAR32FT2000
Biogenic- Jed Kaplan Biogenic- Jed Kaplan wetland inventorywetland inventory
Nitrous OxideNitrous Oxide Anthropogenic- Anthropogenic-
EDGAR32FT2000EDGAR32FT2000 Anthropogenic & Anthropogenic &
Biogenic- GEIABiogenic- GEIAFIRES
Boundary ConditionBoundary Condition
To do even a Geostatistical To do even a Geostatistical Inversion, need ‘background’ values Inversion, need ‘background’ values from where particles are 10 days from where particles are 10 days back in timeback in time
Crucial to have good values here, as Crucial to have good values here, as any error here directly propagates any error here directly propagates into any emissions analysisinto any emissions analysis Biases in particular are of large concernBiases in particular are of large concern
Boundary ConditionBoundary Condition
Data-derived: Globalview type Data-derived: Globalview type product (MBL, time/lat)product (MBL, time/lat) Add vertical shape?? Add vertical shape??
Model-output: Forward model runsModel-output: Forward model runs Atmospheric Inversion output- Atmospheric Inversion output-
carbontracker methanecarbontracker methane
Boundary Condition Boundary Condition InsightsInsights
2 Crucial Points2 Crucial Points Latitude DependenceLatitude Dependence
Vertical gradient over ocean (for ch4) is Vertical gradient over ocean (for ch4) is negligible in comparisonnegligible in comparison
Seasonal VariationSeasonal Variation This must be correct, in order to This must be correct, in order to
prevent seasonal biasesprevent seasonal biases Must check with measurement Must check with measurement
points in free troposphere with points in free troposphere with minimal surface influence– minimal surface influence– aircraft aircraft measurements are crucialmeasurements are crucial
Bottom-Up Model ValuesBottom-Up Model Values
Enhancement + Boundary Value Enhancement + Boundary Value = Modeled Mixing Ratio @ = Modeled Mixing Ratio @ measurement pointmeasurement point
Facilitates direct comparison, Facilitates direct comparison, and optimization of emissionsand optimization of emissions
Case Study- COBRA-NA Case Study- COBRA-NA 20032003
~300 flasks measured @ NOAA/Boulder, UND Citation II, 23 May to 28 June 2003~300 flasks measured @ NOAA/Boulder, UND Citation II, 23 May to 28 June 2003
Measurements- FootprintMeasurements- Footprint
Results- MethaneResults- Methane
Slope: 0.924 ± 0.13
Scaling Factor: 1.08 ± 0.15Note: Prior Emissions Field EDGAR32FT 2000 & JK wetland
Results- Nitrous OxideResults- Nitrous Oxide
Slope: 0.381 ± 0.072
Scaling Factor: 2.62 ± 0.50
Note: Prior Emissions Field EDGAR32FT 2000, similar results using GEIA
But . . .But . . .
Limitations in coverageLimitations in coverage Only a snapshot in time (May- June Only a snapshot in time (May- June
of 2003)of 2003) Seasonality in agricultural Nitrous Seasonality in agricultural Nitrous
Oxide emissions is likely at play.Oxide emissions is likely at play. Want to do with measurements over Want to do with measurements over
multiple years, get full seasonality multiple years, get full seasonality picture.picture.
Concept HereConcept Here
Goal: Incorporate all measurements of Goal: Incorporate all measurements of CH4 and N2O over North America for CH4 and N2O over North America for 2004-20082004-2008
Start: NOAA network, aircraft and Start: NOAA network, aircraft and tower flask samples, for 1 calendar tower flask samples, for 1 calendar year, CH4: under wayyear, CH4: under way Gives an initial framework from which to Gives an initial framework from which to
expand fromexpand from Natural path is to start with same simple Natural path is to start with same simple
approach used previouslyapproach used previously
Combined Footprint, Aircraft Flasks, September 2006
Midday Footprint, LEF, Spring 04
Midday Footprint, AMT, Spring 04
Midday Footprint, WKT, Spring 04
Intensive Aircraft Intensive Aircraft Campaigns & Continuous Campaigns & Continuous
measurementsmeasurements Incorparation of Intensive Aircraft Incorparation of Intensive Aircraft
Campaigns and continuous Campaigns and continuous measurments at towers can strongly measurments at towers can strongly supplement the flask measurement supplement the flask measurement frameworkframework
Pre-HIPPO flight, from Rodrigo Jimenez
LEF mjj, LEF mjj, Model Model
PredictionsPredictions
Model runs at 19 GMT
Data Boundary,
Note: -large day to day variation
-dominance of anthropogenic
emissions
LEF 2004
Model runs at 19 GMT
Note Different slopes w/ different boundaries, indicating different seasonality in boundaries
Texas- model systematically too low
Maine: Model systematically too high
AcknowledgementsAcknowledgements HarvardHarvard
Bruce Daube, Elaine Gottlieb, Steve WofsyBruce Daube, Elaine Gottlieb, Steve Wofsy AERAER
Janusz Eluszkiewicz & Thomas NehrkornJanusz Eluszkiewicz & Thomas Nehrkorn MPI- JenaMPI- Jena
Christoph Gerbig & Stefan KornerChristoph Gerbig & Stefan Korner Netherlands & SwitzerlandNetherlands & Switzerland
Sander Houweling & Jed KaplanSander Houweling & Jed Kaplan NOAA & NCARNOAA & NCAR
Arlyn Andrews, Adam Hirsch, John B. Miller, Brit Stephens, Arlyn Andrews, Adam Hirsch, John B. Miller, Brit Stephens, Colm Sweeney, Lori Bruhwiler, Ed Dlugokencky, Pieter TansColm Sweeney, Lori Bruhwiler, Ed Dlugokencky, Pieter Tans
U MichaganU Michagan Anna MichalakAnna Michalak
University of WaterlooUniversity of Waterloo John LinJohn Lin