Grantee Research Project Results
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: R835037Title: 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. , Henze, Daven K , Grell, Georg , 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 Amount: $895,432
RFA: Black Carbon's Role In Global To Local Scale Climate And Air Quality (2010) RFA Text | Recipients Lists
Research Category: Climate Change , Air
Objective:
We propose to evaluate the effects and uncertainties of BC from pollution and climate perspectives by source sector and by geographic locale, across scales from urban to remote areas. Specifically, we plan to undertake the following scientific objectives: 1. Rank and constrain the contributions of transport, deposition, aerosol properties, and emissions to uncertainty in estimates of BC distributions and radiative forcing. 2. Improve model representation of BC distributions at urban-to-global scales. 3. Develop novel metrics for BC air quality and climate impacts that reflect the competing effects of co-pollutants and account for propagation of uncertainties in source, transport, and radiative processes.
Approach:
We will utilize sensitivity tools and data assimilation within a coupled dynamics –chemical transport modeling system with a wealth of observations from surface measurements, field campaigns and remote sensing products. A new adjoint model for WRF-Chem that includes online dynamical feedbacks of BC will be implemented and applied towards detailed analysis of the sensitivity of estimated BC concentrations and radiative forcing to sources, model transport and deposition parameters, and aerosol properties. Results will guide assimilation of BC observations in three distinct regions: California, India and the Arctic, which were chosen for their contrasting characteristics and density of observations from recent and upcoming field campaigns. Assimilation will proceed systematically, from mass concentrations at surface sites in urban locations, to aircraft data, to remote sensing and optical measurements; this affords isolation and constraint of uncertainty in BC sources, vertical distribution, and radiative impacts. Findings will be validated using independent data and additional models (GEOS-Chem, CMAQ). Finally, both prior and constrained models will then be used to quantify the climate forcing and exposure elasticity and amplification for BC and SO2, and the emissions reduction efficiency for the BC:S ratio, characterizing the metric response to sectoral BC emissions changes at the urban, regional, and global scales.
Expected Results:
This project will provide an unprecedented and much-needed identification and ranking of the sources of uncertainty in BC, its effects on climate, and the impacts of policy actions to reduce its impact on air quality and climate. The estimates of process and emissions uncertainties will immediately inform policy analyses at regional and global scales, as the three models and their emissions have been chosen as representative of the contemporary modeling of BC. Findings will also directly state the relative importance of components of the system to total uncertainty, thereby helping inform future basic research priorities to improving our understanding of this complex system. Adjoint models of chemistry-climate interactions refined through this project will be primary tools for future basic and applied research on these topics.