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Earth Science: Tropospheric Chemistry Studies

RO#

17624

Location

Ames Research Center
Moffett Field, CA 94035-1000

Advisor Information

Name	Phone	Email
Singh, Hanwant B.	(650)604-6769	hsingh@mail.arc.nasa.gov

Research Area

Earth and Atmospheric Sciences

Keywords

Atmospheric chemistry; Atmospheric trace constituents; Troposphere; Climatology; Statistics; Nitrogen oxides;

Description

The chemical composition of the Earth's atmosphere is changing rapidly. A major goal of the global tropospheric experiment (GTE) is to understand the composition and chemistry of the atmosphere so that a realistic assessment of the consequences of such changes can be made. To achieve this goal, GTE aircraft studies were performed in the Brazilian tropics (1987), in the Alaskan Arctic (1988), over the Pacific Ocean (1991, 1994), and over the south tropical Atlantic.

Reactive nitrogen plays a central role in the chemistry of the troposphere. We have developed and flown an instrument (PANAK) that measures peroxy acetyl nitrate (PAN), PPN, CH₃ONO₂, C₂Cl₄, and several oxygenated hydrocarbons to low parts per trillion (ppt) concentrations. These experiments have shown that PAN is a major component of reactive nitrogen and a reservoir for nitrogen oxides in the global troposphere. Furthermore, acetaldehyde and acetone are key intermediate products of hydrocarbon oxidation and precursors for PAN formation. These studies have yielded new information on the presence of Cl atoms and HO_x radicals in the atmosphere. Statistical techniques and one- and two-dimensional photochemical models are used to analyze and interpret these data.