Evaluation of GEOS-5 sulfur dioxide simulations during the Frostburg, MD 2010 field campaign

V Buchard,N Krotkov,H He,A M Da Silva,P Colarco,G Mount,R R Dickerson,J W Stehr,H L Arkinson,E Spinei

doi:10.5194/acp-14-1929-2014

Abstract

Abstract. Sulfur dioxide (SO2) is a major atmospheric pollutant with a strong anthropogenic component mostly produced by the combustion of fossil fuel and other industrial activities. As a precursor of sulfate aerosols that affect climate, air quality, and human health, this gas needs to be monitored on a global scale. Global climate and chemistry models including aerosol processes along with their radiative effects are important tools for climate and air quality research. Validation of these models against in-situ and satellite measurements is essential to ascertain the credibility of these models and to guide model improvements. In this study, the Goddard Chemistry, Aerosol, Radiation, and Transport (GOCART) module running on-line inside the Goddard Earth Observing System version 5 (GEOS-5) model is used to simulate aerosol and SO2 concentrations. Data taken in November 2010 over Frostburg, Maryland during an SO2 field campaign involving ground instrumentation and aircraft are used to evaluate GEOS-5 simulated SO2 concentrations. Preliminary data analysis indicated the model overestimated surface SO2 concentration, which motivated the examination of the specification of SO2 anthropogenic emission rates. As a result of this analysis, a revision of anthropogenic emission inventories in GEOS-5 was implemented, and the vertical placement of SO2 sources was updated. Results show that these revisions improve the model agreement with observations locally and in regions outside the area of this field campaign. In particular, we use the ground-based measurements collected by the United States Environmental Protection Agency (US EPA) for the year 2010 to evaluate the revised model simulations over North America.

Highlights

Sulfur dioxide (SO2) is a trace gas which poses significant health threats near the surface, with consequences on human health (Ware et al, 1986; United States Environmental Protection Agency (US EPA), 2011) and on the ecosystem acidification (Schwartz, 1989)
This result is consistent with the general findings of Sect. 3: the revised vertical placement of SO2 emissions has a positive impact on the simulated surface values of SO2
The Frostburg campaign that took place in Maryland in November 2010 was a good opportunity to evaluate the SO2 simulated by the Goddard Earth Observing System version 5 (GEOS-5)/GOCART system

Summary

Introduction

Sulfur dioxide (SO2) is a trace gas which poses significant health threats near the surface, with consequences on human health (Ware et al, 1986; US EPA, 2011) and on the ecosystem acidification (Schwartz, 1989). With a mean lifetime of few days in the troposphere (Lee et al, 2011; He et al, 2012), emitted SO2 is oxidized to form sulfate aerosols. The resulting aerosols exert influences on the atmospheric radiative balance and cloud microphysics SO2 is emitted into the atmosphere mainly from anthropogenic sources such as fossil fuel combustion and industrial facilities. To keep track of SO2 emissions, this gas is monitored throughout the country by a system of continuously sampling ground-based instruments, and by episodic intensive field campaigns.

Objectives

Results

Conclusion