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 Kortkort@fas.harvardkort@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