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NACP. On network design for the detection of urban greenhouse gas emissions: Results from the Indianapolis Flux Experiment (INFLUX).

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Nacp

NACP

On network design for the detection of urban greenhouse gas emissions: Results from the Indianapolis Flux Experiment (INFLUX)

Natasha Miles1, Marie Obiminda Cambaliza2, Kenneth Davis1, Michael Hardesty3, Laura Iraci4, Kevin Gurney5, Anna Karion3, Thomas Lauvaux1, Laura McGowan1, Scott Richardson1, Daniel Sarmiento1, Paul Shepson2, Colm Sweeney3, Jocelyn Turnbull6, James Whetstone7

1. The Pennsylvania State University, 2. Purdue University, 3. NOAA/ESRL

4. NASA/JPL, 5. Arizona State University, 6. GNS Science, 7. NIST

ICDC9 Beijing7June 2013


Influx motivation

INFLUX motivation

  • Emissions mitigation will happen at local and regional scales.

  • Validation of emissions mitigation will(?) require (independent) measurements

  • Atmospheric GHG measurements have the potential to provide such independent emissions estimates.


Nacp

INFLUX objectives

  • Develop improved methods for determination of urban area-wide emissions, and spatially and temporally-resolved fluxes of greenhouse gases, specifically, CO2 and CH4.

  • Determine and minimize the uncertaintyin the emissions estimate methods.


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INFLUX methodology:

Simultaneous application of multiple methods

  • Inventory estimates of sector-by-sector emissions at high spatial resolution

  • Periodic aircraft flights with CO2, CH4, and flask samples - Whole city flux estimates

  • Periodic automobile surveys of CO2 and CH4 – Emissions from strong point sources (power plants, landfill, gas leaks)

  • 12 surface towers measuring CO2, 5 with CH4, and 5 with CO & Mesoscale atmospheric inversion - Spatially and temporally resolve GHG emissions

  • 5 automated flask samplers from NOAA – Identify sectoralemissions

  • TCCON-FTS for 4 months (Sept-Dec 2012)

  • 4 eddy-flux towers from natural to dense urban landscapes – Model assessment (June 2013)

  • Doppler lidar (installed late April 2013)

  • Tracer release experiment (planned August 2013)


  • Vulcan and hestia emission inventories models

    Vulcan and Hestia Emission Inventories / Models

    250m res - Indy

    Hestia: high resolution emission data for the residential, commercial, industrial, transportation and electricity production sectors.

    Vulcan – hourly, 10km resolution for USA

    http://hestia.project.asu.edu/


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    INFLUX observational results to date:

    Aircraft and automobiles


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    Aircraft mass balance approach: 1 June 2011 Flight path

    Cambaliza et al, in prep


    Nacp

    1 June 2011 Results

    Cambaliza et al, in prep

    50 ppb CH4

    8 ppm CO2

    22,000 moles s-1

    203 moles s-1


    Nacp

    CO2 Emissions: Aircraft mass balance vs Hestia inventory

    • Aircraft mass balance: uncertainty based on measurements of plume at different distances from source: 40%

    • More day-to-day variability in mass balance results

    Cambaliza et al, in prep


    Nacp

    Drive-arounds: Separation/quantification of CH4 sources

    WWTP

    Instrumented

    surface vehicles to

    identify and quantify individual sources.

    Landfill


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    INFLUX observational results to date:

    Ground-based measurements


    Influx ground based instrumentation

    Picarro, CRDS sensors; NOAA automated flask samplers;

    Communications towers ~100 m AGL

    INFLUX ground-based instrumentation

    10 km


    In situ flask comparison at 5 influx sites

    In-situ – flask comparisonat 5 INFLUX sites

    • NOAA 1 hour integrated flask samples

    • Mean value in-situ - flask:

      • CO2: 0.09 ppm

      • CH4: 0.6 ppb

      • CO: -4.1 ppb

    • Within WMO recommendations (urban)


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    Flask results: C14

    ICDC9 Poster 224: Turnbull et al.


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    Tower in-situ results /

    Mesoscaleatmospheric inversion system


    Mesoscale modeling system

    Mesoscale modeling system

    • WRF-Chem running with:

      • 3 nested domains (9/3/1 km resolution), inner domain: 87x87 km2

      • Meteorological data assimilation

      • Hestia anthropogenic fluxes for the inner domain

      • Vulcan anthropogenic fluxes for the outer domains

      • Carbon Tracker posterior biogenic fluxes

      • Carbon Tracker boundary conditions

    • Lagrangian Particle Dispersion Model

    • Bayesian matrix inversion

    T. Lauvaux


    Gain relative improvement prior vs posterior

    Inversion system test

    Gain – relative improvement prior vs. posterior

    Flux units: gC m-2 hr-1.

    Very good system performance within the tower array.

    Very idealized case, but encouraging nonetheless.

    1 = perfect correction to prior fluxes


    Influence functions influx

    Influence functions: INFLUX

    • “Influence function” – the areas that contribute to GHG concentrations at measurement points

  • 12 towers in 87 x 87 km2 domain

  • Strategy: oversampling (?)

  • Contour: Hestia residential sector


    Sectoral atmospheric mole fractions tower by tower

    Sectoral atmospheric mole fractions, tower by tower

    Winter mean mole fractions

    6 of 12 tower sites

    Midday ABL mixing ratio (ppm)

    Site 1: background

    Site 2: downwind

    Site 10: powerplant!

    Some structure across

    towers by sector

    Site 1

    Site 10

    2

    5

    9

    7

    commer

    indust

    mobile

    resid

    powerplant


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    Comparison of [CO2] at INFLUX sites

    • Afternoon [CO2] with 21-day smoothing

    • Site 03 (downtown): high [CO2]

    • Site 09 (rural site to the east of the city): low [CO2]

    • Seasonal and synoptic cycles are evident

    Site 03: downtown

    Site 09: rural

    2012

    * Note: Tower heights range from 40 m AGL to 136 m AGL


    Observed range of co2 amongst influx sites

    Observed range of CO2 amongst INFLUX sites

    < 3 ppm on 29% of days

    > 10 ppm on 10% of days


    Observed range of co2 amongst influx sites1

    Observed range of CO2 amongst INFLUX sites

    < 3 ppm on 29% of days

    > 10 ppm on 10% of days

    29% of ranges are < 3 ppm

    10% of ranges are > 10 ppm


    Co2 range as a function of wind speed

    CO2 range as a function of wind speed

    Observations: CO2 range amongst INFLUX sites

    Increased residence time (at low winds) tends to increase the CO2 range


    Co2 range as a function of wind speed1

    CO2 range as a function of wind speed

    Observations: CO2 range amongst INFLUX sites

    Model: Difference along domain-averaged wind direction

    Increased residence time (at low winds) tends to increase the CO2 range


    Average co2 above background site

    Average [CO2] above background site

    • Compared to Site 01 (background)

    • Site 03 (downtown site) measures larger [CO2] by 3 ppm

    • Site 09 measures only 0.3 ppm larger than Site 01

    Average CO2 (ppm)

    Observations

    Afternoon hours

    Downtown site

    Background site

    East of city

    01 02 03 04 05 07 09 10 12


    Average co2 compared to background site

    Average CO2 compared to background site

    Average CO2 (ppm)

    • Forward model results: using Hestia 2002 fluxes

    • Average: obs 25% higher than predicted

    Background site

    01 02 03 04 05 07 09 10 12


    Average co2 compared to background site1

    Average CO2 compared to background site

    Average CO2 (ppm)

    • Forward model results: using Hestia 2002 fluxes

    • Average: obs 25% higher than predicted

    Background site

    01 02 03 04 05 07 09 10 12


    Conclusions

    NACP

    Conclusions

    • Whole city flux estimates achieved via aircraft mass balance. ~40% uncertainty

    • Winter, CO2 = CO2ff. Summer, not so.

    • Tower observations detect a clear urban signal in both CO2 and CH4 (buried amid lots of synoptic “noise”).

    • Differences vary greatly with weather conditions

    • Inversion system with 6 towers performs very well under idealized conditions.

    • “Real data” forward results encouraging.


    Vertical profiles of co2

    Vertical profiles of CO2

    Rural site

    October 2012


    Vertical profiles of co21

    Vertical profiles of CO2

    Downtown site

    October 2012

    Rural site

    October 2012

    • Downtown site, compared to the top level (54 m):

      • 40 m level is 0.3 ppm higher, averaged over 1 month

      • 20 m level is 1.7 ppm higher

      • 10 m level is 4.3 ppmhigher

    • INFLUX tower heights range from 40 m AGL to 136 m AGL


    Sensitivity test average co2 above background site

    Sensitivity test: Average [CO2] above background site

    • Check sensitivity of results to small errors in modeled winds

    • Hestia fluxes shifted by 1 grid point in each direction

    • Which sites are more useful for reducing uncertainty?

    Background site


    Sensitivity test average co2 above background site1

    Sensitivity test: Average [CO2] above background site

    • Check sensitivity of results to small errors in modeled winds

    • Hestia fluxes shifted by 1 grid point in each direction

    • Which sites are more useful for reducing uncertainty?

    • Differences of 0.5 – 1 ppm at sites 03, 07, and 10

    • Lower at other sites

    Background site


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