Cavity-Enhanced Spectroscopy for In Situ Measurements and Atmospheric Monitoring of Tropospheric Pollutants

EPA Grant Number: U916143
Title: Cavity-Enhanced Spectroscopy for In Situ Measurements and Atmospheric Monitoring of Tropospheric Pollutants
Investigators: Engel, Gregory S.
Institution: Harvard University
EPA Project Officer: Lee, Sonja
Project Period: January 1, 2003 through January 1, 2006
Project Amount: $84,186
RFA: STAR Graduate Fellowships (2003) Recipients Lists
Research Category: Academic Fellowships , Air Quality and Air Toxics , Fellowship - Atmospheric Sciences


The objective of this research project is to probe the complex responses of the atmosphere and elucidate causal relations to anthropogenic forcings to determine measurements capable of quantifying a host of atmospheric species, including isotopomers, radicals, and tracer species both in the free troposphere and on the ground.


These measurements will serve both to quantify pollutant budgets and to improve policy regarding atmospheric pollutants on regional and local scales. Such measurements present specific criteria for instrument design: the detection technique must be sufficiently general to allow many species to be monitored, sufficiently compact and lightweight to allow flights on small aircraft, sufficiently robust to require little maintenance, and sufficiently simple to produce reliable and trusted results. Advancements in Cavity-Enhanced Laser Absorption Spectroscopy address all these requirements, while offering exceptional sensitivity because of long effective path lengths (>30 km) of the high-finesse optical cavity. I will demonstrate technological advancements to allow scalable, modular, lightweight instrument construction with the necessary sensitivity for the most demanding measurements, while providing multiple, direct calibration methods. In particular, I will focus on advancements in Integrated Cavity Output Spectroscopy and Cavity Ringdown Spectroscopy improving detection limits to 2.9 x 10-11 cm-1 / Hz0.5.

Supplemental Keywords:

fellowship, atmospheric pollutants, tropospheric pollutants, cavity-enhanced spectroscopy, atmospheric monitoring, radicals, tracer species.

Progress and Final Reports:

  • 2003
  • 2004
  • Final