Helping the EPA develop a better way to measure ammonia pollution by analyzing satellite data

Karen Cady-Pereira, Staff Scientist, AER
April 13, 2011

Ammonia is a trace gas that contributes to pollution. Much of the ammonia in the U.S. comes from livestock waste and fertilizer. It’s an integral part of the nitrogen cycle; but excess ammonia is associated with algae blooms and ammonia reacts with sulfate and nitric acid in the atmosphere to form fine particulate matter, a pollutant linked to respiratory ailments.

Monitoring ammonia is a challenge since it’s a highly reactive and thus highly variable trace gas. To tackle this challenge, AER helped the U.S. Environmental Protection Agency (EPA) develop a new approach to measure ammonia pollution as well as determine and track the sources of ammonia. Since the monitoring network is very sparse over most of the Earth, AER proposed using satellite data to measure ammonia from space and then developed the ammonia retrieval algorithm.

AER initiated a cooperative effort with the EPA and the University of Colorado to develop and validate an algorithm for retrieving ammonia from the AURA TES instrument. AURA is part of the A-train, a collection of polar orbiting satellites. The Tropospheric Emission Spectrometer (TES) is a high resolution infrared Fourier transform spectrometer.

We developed and tested the algorithm, while working with the TES team at JPL to schedule intensive observations over North Carolina, where the EPA had deployed a temporary network of in situ NH3 instruments. Analysis of the satellite-based TES and the ground-based EPA measurements showed good correlation in time and space.

AER then performed hundreds of ammonia retrievals over five years and twelve distinct regions of the Earth and produced a global picture of how ammonia amounts vary by season and location.

You can read more about AER’s development of the ammonia retrieval algorithm for EPA using the NASA AURA TES instrument and EPA’s article on the project’s success.