AirCore: Elegant, Cost Effective Method to Collect Trace Gas Profiles
Global Monitoring Division -
NOAA/ESRL scientists from the Carbon Cycle and Greenhouse Gases group are testing a novel and very cost effective method of collecting high resolution vertical profiles of trace gas concentrations. The system uses long (>150 m) coils of thin walled stainless-steel tubing carried aloft on high altitude balloons or aircraft. With one end closed and the other open to the outside air, ambient air is forced into the column as the coil descends from high altitude to low altitude. Upon landing, the open end of the coil is capped, thus preserving the air inside. The air in the coil does not mix due to the small diameter of the coil thus maintaining a continuous profile of trace gas concentrations as a function of altitude. The Aircore system is about to receive a U.S. patent.
Background: Profiles of climatically important trace gases are presently collected in flasks of up to one liter in volume flown in light aircraft. Due to their size and weight, generally no more than a dozen flask samples are collected per flight. The flask sampling system, flasks and dedicated aircraft are expensive to operate and bulky to handle. The AirCore system is cheap to construct, rugged, light, can be flown on any aircraft of opportunity, and it produces a continuous record of trace gas concentrations providing 100-s of data points per profile. In a recent test flight from Boulder, Colorado, the gas concentrations measured with the AirCore were essentially indistinguishable from concentrations measured of methane and carbon dioxide in flasks exposed at various altitudes in the profile.
Significance: The AirCore is a breakthrough in atmospheric gas concentration profiling because of its simple design, operation, and low cost. Because the AirCore can easy be loaded onto commercial and private aircraft, or carried aloft with small balloons, it provides enormous potential to increase atmospheric profiles of trace gases on a global scale. It is feasible that 1000 or more profiles of a wide range of trace gases could be collected cheaply on a daily basis around the globe limited only by shipping and analyses constraints. Presently about 20 vertical profiles of trace gases are collected globally each week by NOAA ESRL. Using AirCore, multiple profiles of CO2, CH4, and other trace gases will play an essential role in the validation of satellite observations and atmospheric transport models as well as providing data to monitor sources and sinks of climate altering radiative trace species.