Constraining a Historical Black Carbon Emission Inventory of the United States for 1960-2000

Tianye Sun, Liang Liu, Tami C Bond, Mark Flanner, Thomas W. Kirchstetter, Chaoyi Jiao, Chelsea V. Preble, Wayne Chang

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True emissionEstimated emission

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True emissionEstimated emission

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Estimated emission

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Estimated emission Observed concentration

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Motivation: Why Constrain BC Emission?

• Mismatch of the trend between long-term BC emission inventory and ambient air concentration.

• Decreasing trend is observed from measurement but not in emission inventory (peaks in 1980s).

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1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

BC

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men

t ug/

m3

BC

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g/yr

BC Emission

BC Measurement

BC Emission and concentration of California

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Method: How to Constrain BC Emission?

Atmospheric Transport study

Emission Constraining process

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Surface Concentration, C0

BC Emission Inventory

2000-2005, E0

CAM Simulation

Transport Matrix, T

Atmospheric Transport study

Emission Constraining process

Method: How to Constrain BC Emission?

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Historical Emission Inventory

1960s-2000s Eh

ModeledHistorical BC

Concentration, Cre

Measured BC Concentration, Cm

Discrepancy between

Cre and Cm

Transport Matrix, T

Constraint on Emission Inventory

Atmospheric Transport study

Emission Constraining process

Method: How to Constrain BC Emission?

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Method: How to Constrain BC Emission?

Historical Emission Inventory

1960s-2000s Eh

ModeledHistorical BC

Concentration, Cre

Measured BC Concentration, Cm

Discrepancy between

Cre and Cm

Surface Concentration, C0

BC Emission Inventory

2000-2005, E0

CAM Simulation

Transport Matrix, T

Constraint on Emission Inventory

Atmospheric Transport study

Emission Constraining process

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Historical Emission Inventory

1960s-2000s Eh

ModeledHistorical BC

Concentration, Cre

Measured BC Concentration, Cm

Discrepancy between

Cre and Cm

Historical Climate forcing

Fuel use and Technology

Surface Concentration, C0

BC Emission Inventory

2000-2005, E0

CAM Simulation

Upstream

Downstream

Transport Matrix, T

Constraint on Emission Inventory

Atmospheric Transport study

Emission Constraining process

Method: How to Constrain BC Emission?

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BC Emission Inventory:• Emission inventory of Bond et al. [2007] with updates as described

Lamarque et al. [2010]New in this work:• US EIA 2010 state level activity data • SPEW-Trend vehicle fleet model for vehicle emission

BC Measurement data• BC concentrations are estimated from coefficient of haze (COH) data.• Data are available for California and New Jersey for 1960-2005, for other

seven states during 1965 – 1980.Data acquired from the California Air Resources Board (CARB), the New Jersey Department of Environmental Protection (NJDEP), and the Environmental Protection Agency’s Air Quality System.

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Modeled BC Concentration and Measured BC Concentrationof California for 1980s

𝜇𝜇g/m

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1980sMeasurement

Modeled BC

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Adjust Modeled BC Concentration to Account for Error in Model Meteorology

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PBL in the model, m PBL measurement, m

Planetary Boundary Layer for Bay Area.Model vs. Measurement (Data from MERRA, NASA)

𝜇𝜇g/m

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1980sMeasurement

Modeled BC, adjusted meteorology

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Apply Heating Degree Days to Construct Seasonality of Emission in 1980s

Heating degree days for California, 1980s (Data from NOAA)

Use historical seasonal temperature record (heating degree days, HDD) to calculate seasonality of emissions

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°C

𝜇𝜇g/m

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1980sMeasurement

Modeled BC - adjusted meteorology, applied HDD

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Adjust BC Emission with the remaining discrepancy with measurement for 1980s

Emission adjustment factor for California BC in 1980s

Seasonal emission is zero in summer (heating emission)

Concentration is proportional to emission.𝜇𝜇g

/m3

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1980sMeasurement

Modeled BC - adjusted meteorology, applied HDD

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1980s

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Baseline emission

Seasonal emission

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Modeled Concentration from Adjusted BC Emissions for 1980s𝜇𝜇g

/m3

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1980sMeasurementModeled BC - adjusted meteorology, applied HDD, adjusted emissionModeled BC - adjusted meteorology, applied HDD

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Modeled BC Concentration and Measured BC Concentrationof California for 1960s- 2000s

• Decreasing trend is observed from BC measurement for 1960s -2000s, but not in emission inventory (peaks in 1980s).

• Adjusted BC emission shows an overestimation of seasonality for 1960s• Heating Degree Days can explain most of the trend in seasonal variation of the BC

measurement.

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Jan MarMay Jul Sep Nov Feb Apr Jun Aug Oct Dec Jan MarMay Jul Sep Nov Feb Apr Jun Aug Oct Dec Jan MarMay Jul Sep Nov

1960s 1970s 1980s 1990s 2000s

𝜇𝜇g/m

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MeasurementModeled BC - adjusted meteorology, applied HDD, adjusted emissionModeled BC - adjusted meteorology, applied HDD

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Spatial Heterogeneity in Model-Measurement Comparison

• BC concentration in different resolution could be vary by a factor of two.

• Emission adjustment is divided by a factor of two to account for this resolution uncertainty.

• Trend is more instructive than the absolute magnitude since the measurement and the model are in different resolution

Comparison of BC concentration distribution modeled for Los Angeles with three different resolutions

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Adjustment factor for Baseline Emission and Seasonal Emission for 1960s to 2000s

• Adjustment factors for baseline emission decrease through the study period. Emissions need a 2.5-fold increase in the 1960s.

• Adjustment factors for seasonal emission are large in 1960s, 1970s, and 2000s, and relatively small in 1980s.

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�1960s �1970s �1980s �1990s �2000s

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Baseline emissionSeasonal emission

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Conclusion

1. Decreasing trend is observed from BC measurement for 1960s -2000s, but not in emission inventory (peaks in 1980s).

2. Heating Degree Days can explain most of the trend in seasonal variation of the BC measurement.

3. To reproduce the decreasing trend, higher emission factors are needed for 1960s to 1970s.

Future Work1. Multi states measurements can be used as orthogonal basis to constrain

historical emission from different fuel-technology sources via transport matrices.

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Vincent van Gogh (Dutch, 1853 – 1890) Self-Portrait, 188923