Human Influence on Ozone in the Tropical Troposphere: An Interpretation of Observations Using a Global Three-dimensional Model

EPA Grant Number: R824096
Title: Human Influence on Ozone in the Tropical Troposphere: An Interpretation of Observations Using a Global Three-dimensional Model
Investigators: Jacob, Daniel J. , Logan, Jennifer A. , Spivakovsky, Clarisa M. , Wofsy, Steven C.
Institution: Harvard University
EPA Project Officer: Shapiro, Paul
Project Period: October 1, 1995 through September 30, 1998 (Extended to March 31, 1999)
Project Amount: $415,798
RFA: Exploratory Research - Chemistry and Physics of Air (1995) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Air , Engineering and Environmental Chemistry


The purpose of this project is to investigate the effects of human activity on ozone in the tropical troposphere. A major feature of the ozone distribution is a region of high concentrations over Brazil, Africa, and the south tropical Atlantic in austral spring, with much lower values over the western Pacific. Analyses of recent field studies show that most of the ozone is formed photochemically, with emissions from biomass burning playing an important role as a precursor of NO; production of NO from lightning also appears to be an important source of NO at the end of the burning season. Transport mechanisms appear important in "containing" the high ozone values over the region. Increases in biomass burning, as occurred in Brazil during the 1980s, could potentially lead to increases in ozone in the upper troposphere, with consequences for climate. The project involves using a three-dimensional chemical tracer model (CTM) to investigate the mechanisms that are responsible for the observed ozone distribution. As part of this study, an inventory of emissions of NO, CO, and hydrocarbons from biomass burning is being developed. The CTM allows also for production of NO by soils and by lightning, and includes the GEIA inventory for fossil fuel emissions. The CTM includes emissions of hydrocarbons and CO, complete chemistry, surface deposition, and rainout of soluble gases. The model will be evaluated with observations of the vertical distribution of ozone, surface data for ozone and CO, and aircraft data for NO, HNO3, PAN, CO, and hydrocarbons. Research objectives are: (1) To define quantitatively export fluxes of ozone and ozone precursors from biomass burning on the tropical continents; (2) To evaluate the role of transport in maintaining the ozone maximum observed over the tropical south Atlantic in the austral spring, (3) To determine the fate of emissions from biomass burning in the northern tropics, and the role of dynamical processes in the tropics in December to March versus July to October; (4) To investigate the role of lightning as a precursor for ozone in the tropics; and (5) To diagnose the net effect of biomass burning on the global oxidizing power of the atmosphere.

Publications and Presentations:

Publications have been submitted on this project: View all 3 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 3 journal articles for this project

Supplemental Keywords:

air, ambient air, atmosphere, oxidants, ozone, tropospheric, particulates, nitrogen oxides, environmental chemistry, modeling, Northeast, Atlantic coast, Massachusetts, MA, Region 1., RFA, Scientific Discipline, Air, Geographic Area, Physics, Environmental Chemistry, climate change, Air Pollution Effects, tropospheric ozone, Engineering, Chemistry, & Physics, International, Atmosphere, ambient aerosol, transport model, Brazil, environmental monitoring, atmospheric particles, hydrocarbon, air modeling, ozone, climate variations, biomass, chemical detection techniques, chemical transport modeling, chemical kinetics, human exposure, global three dimensional model, Africa, troposphere, fossil fuel emissions, atmospheric models

Progress and Final Reports:

  • 1996
  • 1997
  • 1998
  • Final Report