Scientists from across NOAA's Earth System Research Laboratories (ESRL) are working with NASA to evaluate a new laser technique for the remote measurement of tropospheric CO₂ concentrations from space. On November 9, 2007 a team from NASA-Goddard brought their CO2 laser to ESRL's Boulder Atmospheric Observatory (BAO) in Erie, CO for an intensive week-long field study. The laser will be set-up at the Erie High School and pointed at a reflector placed at the top of the BAO tower. This prototype CO2 sensor uses robust laser technology developed by the telecommunications industry. Measurements from the NASA sensor will be compared to continuous CO₂ measurements from three heights on the BAO tower that are part of ESRL Global Monitoring Laboratory's Tall Tower CO₂ monitoring program. ESRL's Chemical Science Division is also contributing to the experiment by putting one of their aircraft CO₂ systems on the BAO's profiling instrument carriage.

Background:
The BAO tower has been operated by the ESRL Physical Sciences Laboratory since the mid-1970s and serves as a unique facility for monitoring the Earth's atmospheric boundary layer. The 300 m tower at the BAO is equipped with sensors that continuously monitor CO₂ from 3 levels on the tower, and an instrument carriage that carries an additional sensor up and down the tower to acquire complete vertical profiles of CO₂.

The NASA Orbiting Carbon Observatory (OCO) is the first space mission focused on atmospheric CO₂ for measuring total column CO₂ and O₂ by measuring the spectral absorption in reflected sunlight. The recent Decadal Survey for Earth Science by the US National Research Council has recommended a subsequent laser-based CO₂ measuring mission called ASCENDS.

Significance:
Accurate measurements of tropospheric CO₂ abundances with global-coverage and monthly temporal resolution are needed to quantify processes that regulate CO₂ exchange with the land and oceans. This short but intensive one-week experiment will provide valuable data for advancing the design of laser-based instrumentation for measurements of CO₂ from space. This activity supports NOAA's mission goal of understanding climate variability and change to enhance society's ability to plan and respond.