2013 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: R835037
Title: 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
Investigators: Carmichael, Gregory R. , Grell, Georg , Henze, Daven K , Spak, Scott
Institution: University of Iowa , National Oceanic and Atmospheric Administration , University of Colorado at Boulder
EPA Project Officer: Chung, Serena
Project Period: September 1, 2011 through August 31, 2014 (Extended to August 31, 2015)
Project Period Covered by this Report: September 1, 2012 through November 18,2013
Project Amount: $895,432
RFA: Black Carbon's Role In Global To Local Scale Climate And Air Quality (2010) RFA Text |  Recipients Lists
Research Category: Global Climate Change , Climate Change , Air

Objective:

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.

Progress Summary:

A major activity during this period was constraining black carbon aerosol over Asia using OMI Aerosol Absorption Optical Depth and the GEOS-Chem adjoint. Constraining black carbon (BC) using observations is crucial for estimating emission uncertainties and improving model simulations. OMI Aerosol Absorption Optical Depth (AAOD) is a measure of the concentration of absorbing aerosol particles, such as BC and mineral dust. While a potentially valuable observational constraint on BC, the application of OMI AAOD requires reasonable simulations of dust versus BC, because the AAOD is the combined contribution of all absorbing aerosols. Due to the significant positive biases identified in GEOS-Chem dust simulations both in surface concentrations and aerosol optical depth, new emitted dust particle size distributions were implemented in GEOS-Chem and dust AOD and AAOD predictions were improved as described in the publication of Zhang et al., 2013.  With this improvement in dust simulations, BC emissions were optimized by the assimilation of OMI AAOD using the GEOS-Chem adjoint. Overwhelming enhancements of anthropogenic emissions for BC are shown after optimization over broad areas of Asia in April, up to 500% (Fig. 1). In October, the optimization of anthropogenic emissions yields a slight reduction (1~5%) over India and part of south China while it increases by 10~50% over eastern China. Using surface observations of BC concentrations in China it is found that a priori BC surface concentrations are underestimated in most of the urban and rural sites over China. Though the optimized BC surface concentrations are enhanced in April, it also causes overestimation in some eastern sites over China. In October, the low biases are corrected both in the urban sites and rural sites, especially the eastern rural sites. However, there is still low bias in most of the sites after optimization. The monthly discrepancies also might relate to the model uncertainties of representativeness in transport and resolution.
 
 
Work on building and applying the WRF-Chem adjoint was continued. 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. We also have developed and validated stand-alone adjoint and tangent linear modules of the Grell-Freitas cumulus convection and ACM2 planetary boundary layer schemes that will be released in WRF V3.5.1 with chemical tracer transport.  ACM2 also will include dry deposition. In both the cumulus and PBL schemes, the adjoint and TL values match the finite difference values to numerical precision, indicating that the new derivative codes are accurate.  
 
We also have further evaluated the BC transport and source sector/region contributions to BC in Asia using new observations of BC and PM2.5 in Central Asia. On an annual basis the power and industrial sectors were found to be the most important contributors to PM2.5, while residential and transportation were the most important sectors for BC. Open biomass burning within and outside the region also contributed to elevated PM and BC concentrations and to the temporal variability. Observations in this region are of growing importance as it is estimated that PM2.5 levels are likely to increase significantly in Central, South Asia and western China over the next few decades. To address the question of how PM2.5 and BC might change in the next few decades, simulations were repeated for various emission scenarios developed and used in the WMO/UNEP assessment on short-lived climate pollutants. Under a reference scenario that reflects all present agreed policies affecting emissions and assumes that they are fully implemented, PM2.5 increases significantly in South Asia and western China (>50%) and in parts of CA, including the area where the sampling sites are located. PM2.5 decreases appreciably in Western Europe and Eastern China (< 10%). BC surface concentrations show a similar pattern, with the exception of the areas of increases extending through larger portions of CA, and with larger increases in BC than in PM2.5. These results suggest that health impacts and climate warming due to these particles may increase in coming decades unless additional emission control measures are implemented.
 
We have conducted global adjoint calculations in GEOS-Chem for speciated aerosol emissions sensitivities, direct radiative forcing, and population-weighted concentrations with both present-day and future emissions scenarios. From these, we have calculated novel radiative forcing metrics, including Forcing Amplifier and Emissions Reduction Efficiency by sector and region, for all global megacities, as well as the urban areas with the greatest impact on the Arctic. This analysis has identified regions and activities where air quality improvements are a minor co-benefit to mitigating SLCF, and where SLCF reduction is a co-benefit to PM2.5 reductions.

Future Activities:

  • Comprehensive regional-scale sensitivity and assimilation studies.
  • WRF-Chem adjoint development.
  • Source sector/region contributions to BC concentrations and radiative forcing.
  • Quantifying emissions and process uncertainties in adjoint radiative forcing metrics.
  • Submission of new paper.


Journal Articles on this Report : 5 Displayed | Download in RIS Format

Other project views: All 64 publications 21 publications in selected types All 21 journal articles
Type Citation Project Document Sources
Journal Article 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. R835037 (2012)
R835037 (2013)
R835037 (2014)
R835037 (Final)
  • Full-text: Science Direct-Full Text HTML
    Exit
  • Abstract: Science Direct-Abstract
    Exit
  • Other: Science Direct-Full Text PDF
    Exit
  • Journal Article Marrapu P, Cheng Y, Beig G, Sahu S, Srinivas R, Carmichael GR. Air quality in Delhi during the Commonwealth Games. Atmospheric Chemistry and Physics 2014;14(19):10619-10630. R835037 (2013)
    R835037 (2014)
    R835037 (Final)
  • Full-text: ACP-Full Text-PDF
    Exit
  • Abstract: ACP-Abstract
    Exit
  • Other: ResearchGate-Abstract & Full Text-PDF
    Exit
  • Journal Article Saide PE, Carmichael GR, Liu Z, Schwartz CS, Lin HC, da Silva AM, Hyer E. Aerosol optical depth assimilation for a size-resolved sectional model: impacts of observationally constrained, multi-wavelength and fine mode retrievals on regional scale analyses and forecasts. Atmospheric Chemistry and Physics 2013;13(20):10425-10444. R835037 (2013)
    R835037 (2014)
    R835037 (Final)
  • Full-text: ACP-Full Text PDF
    Exit
  • Abstract: ACP-Abstract
    Exit
  • Other: Harvard University-Abstract
    Exit
  • Journal Article Tsao C-C, Campbell JE, Mena-Carrasco M, Spak SN, Carmichael GR, Chen Y. Biofuels that cause land-use change may have much larger non-GHG air quality emissions than fossil fuels. Environmental Science & Technology 2012;46(19):10835-10841. R835037 (2013)
    R835037 (2014)
    R835037 (Final)
  • Abstract from PubMed
  • Full-text: ResearchGate-Abstract & Full Text PDF
    Exit
  • Abstract: ES&T-Abstract
    Exit
  • Other: ES&T-Full Text PDF
    Exit
  • Journal Article Zhang L, Kok JF, Henze DK, Li Q, Zhao C. Improving simulations of fine dust surface concentrations over the western United States by optimizing the particle size distribution. Geophysical Research Letters 2013;40(12):3270-3275. R835037 (2013)
    R835037 (2014)
    R835037 (Final)
  • Full-text: Wiley Online-Full Text HTML
    Exit
  • Abstract: Wiley Online-Abstract
    Exit
  • Other: Wiley Online-Full Text PDF
    Exit
  • Progress and Final Reports:

    Original Abstract
    2012 Progress Report
    2014 Progress Report
    Final Report