2012 Progress Report: Constraining Urban-To-Global Scale Estimates of Black Carbon Distributions, Sources, Regional Climate Impacts, and Co-Benefit Metrics with Advanced Coupled Dynamic - Chemical Transport - Adjoint Models
EPA Grant Number:
Constraining Urban-To-Global Scale Estimates of Black Carbon Distributions, Sources, Regional Climate Impacts, and Co-Benefit Metrics with Advanced Coupled Dynamic - Chemical Transport - Adjoint Models
Carmichael, Gregory R.
, Grell, Georg
, Henze, Daven K
, Spak, Scott
University of Iowa
National Oceanic and Atmospheric Administration
University of Colorado at Boulder
EPA Project Officer:
September 1, 2011 through
August 31, 2014
(Extended to August 31, 2015)
Project Period Covered by this Report:
September 1, 2011 through August 31,2012
Black Carbon's Role In Global To Local Scale Climate And Air Quality (2010)
Global Climate Change
In this project we will evaluate and rank sources of uncertainty in modeling BC concentrations and their radiative impacts. The uncertainties analyzed will include those associated with model parameters as well as model structure. We will use this information to improve model representation of BC distributions. We will reduce the uncertainties in BC distributions and radiative impacts through the close integration of observations and models. We will evaluate the uncertainties using novel metrics developed in this project, that will reflect competing effects of co-pollutants and that account for air quality and climate impacts.
A major activity of the first phase of the project was the calculation of source sector/region contributions to BC concentrations and radiative forcing for the continental US, the Northern Hemisphere including the Arctic as a receptor region, and India. For example, the contributions of various anthropogenic and biomass burning sector and source geographical region emissions to BC surface/vertical distributions and column amounts in the year 2008 were calculated. Illustrative examples for the summer of 2008 over ten EPA regions (see Figure) show that over 80% of the surface BC concentrations were dominated by NA emissions except for the western US (Regions 8 and 10), where the non-NA emissions contributed to 30-80% of column BC depending on region. Residential, transportation and biomass burning were the major non-NA contributors. The long range transport contributions are larger for the column amount metric than for the surface concentrations. On an annual basis, domestic and transport sectors had the largest impacts to BC in the northen hemisphere, and the relative importance of each sector was different for the eastern (highest contribution from residential sources) and western hemispheres (transport sector most important).
Caption: Stack plots of contributions from eleven sectors to US (a) surface BC (mg/m3) and (b) column BC (mg/m2) during 06/13-06/26, 2008. (Huang et al. Atmos. Environ.,1, 021, 2012).
Analysis of the major model uncertainties including those related to anthropogenic BC emissions, model resolution, and boundary conditions were also initiated. Reducing uncertainties in anthropogenic emission is crucial for BC simulation. Simulations using four different carbonaceous anthropogenic emission inventories (which exceed 100% across broad areas) were compared with monthly and daily ground-based measurements of four sites are selected from northern China. All the model simulations underestimated surface BC concentration at most of the urban sites, but the results were improved when taking into accounts the seasonal emissions associated with heating. Adjoint sensitivity analysis of the discrepancy between observed and simulated BC concentrations suggest underestimation of anthropogenic emission associated with specific cities (e.g., Xi'an) and surrounding areas. The prediction skill also increased with higher spatial resolution. Results using 8 km horizontal resolution when compared to those using 80km resolution were improved, with differences (increases in the polluted regions) in surface concentrations exceeding 50% across broad areas, even up to 100% in some regions.
Work on building and applying the WRF-Chem adjoint was initiated. Activities included adding BC as a tracer to the WRFPLUS model and building the adjoint of various WRF-Chem modules that handle aerosol feedbacks to meteorology, including the aerosol mixing-activation and a microphysics parameterization that deal with indirect effects, and the radiation and optical properties routines used in the direct and semi-direct interactions. These components have been added to the operational Gridpoint Statistical Interpolation (GSI) tool, which is being used in assimilation studies designed to produce optimized fields of PM2.5 and BC for use in subsequent studies. The WRF-Chem adjoint for BC will be used for sensitivity analysis and assimilation studies in the next phase of the project.
Comprehensive regional-scale sensitivity and assimilation studies.
WRF-Chem adjoint development.
Source sector/region contributions to BC concentrations and radiative forcing.
Adjoint radiative forcing metrics and their uncertainties.
on this Report
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|| Huang M Carmichael GR, Kulkarni S, Streets DG, Lu Z, Zhang Q, Pierce RB, Kondo Y, Jimenez JL, Cubison MJ, Anderson B, Wisthaler A. Sectoral and geographical contributions to summertime continental United States (CONUS) black carbon spatial distributions. Atmospheric Environment 2012;51:165-174.
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Progress and Final Reports:
2013 Progress Report
2014 Progress Report