Continuous Isotopic CO2 Measurements by Wavelength-Scanned Cavity Ring Down Spectroscopy: Studies of Exchange Processes in Terrestrial Ecosystems

Picarro has developed an isotope analyzer for lab and field measurements of carbon isotopes in CO2 with the goal of allowing turnkey analysis to be done without the need for flask samples and complex IRMS methods. Here we present a description of the analyzer and its technology as well as recent results from two different collaborators who utilized the analyzer.

Measuring Stable Isotopes of Water in Both Gas and Liquid Phase Using a Single Field-Deployable Analyzer

Results presented from field trials at Woods Hole Oceanographic Institute and laboratory tests at INSTAAR of a newly available analyzer capable of performing continuous measurements of stable isotopes (δD and δ18O) of liquid water and / or water vapor samples.

The analyzer is designed such that it does not require frequent calibration; it maintains high linearity, precision, and accuracy for long periods of time, over changing environmental conditions, with little or no sample preparation. The complete system is small and portable enough for field use.

High-Precision Measurements of CO2, CH4 and H2O for Atmospheric Inversion and Eddy Covariance Flux Based on Cavity Ring Down Spectroscopy.

Field deployable instrumentation that measures carbon dioxide, methane, and water vapor with both high-accuracy and high-precision would reduce the uncertainty in the determination of terrestrial sources and sinks of these dominant greenhouse gases, resulting in improved predictive models and a deeper understanding of the global carbon cycle. Existing atmospheric monitors based on non-dispersive infrared sensors have known problems - they are non-linear, sensitive to water vapor concentration, and susceptible to drift. Furthermore, these instruments require extensive modifications and sample conditioning, frequent zero and span calibrations, and significant post processing of the data. Additionally, many cannot easily be calibrated simultaneously from site to site to the level of accuracy required for use in atmospheric inversion studies. Picarro has developed a line of high-precision carbon dioxide/methane/water vapor analyzers for atmospheric inversion and Eddy Covariance Flux measurements that maintain high linearity, precision, and accuracy over changing environmental conditions, with minimal calibration. The outstanding performance is based on a combination of the unique capabilities of the underlying optical absorption technology, Cavity Ring Down Spectroscopy (CRDS), and engineering designed to maximize the inherent advantages of CRDS including a high-precision wavelength monitor that ensures only the spectral absorption feature of interest is being monitored. Precise temperature and sub-torr pressure control enables excellent accuracy from analyzer to analyzer and low drift over time- important considerations for a network of measurement sites. The extremely compact cell size gives the analyzer fast rise and fall times at very small flow rates translating into significantly reduced calibration gas volumes and enabling a true 10 Hz response. Because the analyzers do not require sample conditioning or frequent calibration and maintain high linearity, precision, and accuracy over changing environmental conditions, these analyzers could significantly improve the accuracy and precision of greenhouse gas measurements while reducing the operating costs of monitoring, enabling higher density deployment.

A Field-Deployable, High Accuracy Atmospheric Multi-Gas Monitor Based on Cavity Ring-Down Spectroscopy

Picarro has developed a field-deployable, real time, ambient gas monitor capable of measuring atmospheric levels of carbon dioxide, methane, hydrogen sulfide, and ammonia with parts-per-billion (ppbv) sensitivity and water vapor with parts-per-million (ppmv) sensitivity. Results from field trials of three different CO2 analyzers at Harvard, Penn State, and the NOAA facility in Boulder CO are shown.

An ultra-sensitive, six-species trace gas analyzer for continuously monitoring concentrated animal feeding operations.

The need for multi-species, trace gas analysis in industries ranging from petrochemical process control to combustion analysis to environmental monitoring is driving the development of process analyzers with both high sensitivity and high speed. Wavelength-Scanned Cavity Ring-Down Spectroscopy (WS-CRDS) is a laser-based, all-optical technique capable of parts-per-billion sensitivity and fast >1 Hz measurement rates. It is effective in even the most complex gas streams, without long term drift or periodic calibration requirements. A high finesse optical cavity coupled to a high precision wavelength monitor enable the analyzer to have a spectral resolution 1000 times better than a Fourier Transform Infrared Spectrometer (FTIR) thus allowing it to distinguish individual absorption features. Picarro, Inc. has developed a WS-CRDS gas analyzer that can measure up to six separate species. This multi-component analyzer gives the same performance, inherent stability, and reliability as the standard single-species gas analyzers. The modular broadband design enables configuration of the multi-species platform to any four of a variety of target species. Results obtained measuring six important atmospheric contaminants (hydrogen sulfide, ammonia, nitrous oxide, carbon dioxide, water vapor and methane) that are of interest to researchers monitoring Concentrated Animal Feeding Operations (CAFOs) are shown.