Remote sensing measurements of the CO sub(2) mixing ratio in the planetary boundary layer using cloud slicing with airborne lidar

We have measured the CO sub(2) volume mixing ratio (VMR) within the planetary boundary layer (PBL) using cloud slicing with an airborne pulsed integrated path differential absorption (IPDA) lidar from flight altitudes of up to 13km. During a flight over Iowa in summer 2011, simultaneous measurement...

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Bibliographic Details
Published in:Geophysical research letters 2015-03, Vol.42 (6), p.2055-2062
Main Authors: Ramanathan, Anand K, Mao, Jianping, Abshire, James B, Allan, Graham R
Format: Article
Language:English
Subjects:
Carbon dioxide
Cirrus clouds
Clouds
Cumulus clouds
Grounds
Lidar
Mixing ratios
Planetary boundary layer
Remote sensing
Slicing
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Summary:We have measured the CO sub(2) volume mixing ratio (VMR) within the planetary boundary layer (PBL) using cloud slicing with an airborne pulsed integrated path differential absorption (IPDA) lidar from flight altitudes of up to 13km. During a flight over Iowa in summer 2011, simultaneous measurement of the optical range and CO sub(2) absorption to clouds and the ground were made using time-resolved detection of pulse echoes from each scattering surface. We determined the CO sub(2) absorption in the PBL by differencing the two lidar-measured absorption line shapes, one to a broken shallow cumulus cloud layer located at the top of the PBL and the other to the ground. Solving for the CO sub(2) VMR in the PBL and that of the free troposphere, we measured a approximately 15ppm (4%) drawdown in the PBL. Both CO sub(2) VMRs were within approximately 3ppm of in situ CO sub(2) profile measurements. We have also demonstrated cloud slicing using scatter from thin, diffuse cirrus clouds and cumulus clouds, which allowed solving for the CO sub(2) VMR for three vertical layers. The technique and retrieval algorithm are applicable to a space-based lidar instrument as well as to lidar IPDA measurements of other trace gases. Thus, lidar cloud slicing also offers promise toward space-based remote sensing of vertical trace gas profiles in the atmosphere using a variety of clouds. Key Points * Cloud slicing with lidar can sense CO sub(2) in the planetary boundary layer * Lidar cloud slicing has been demonstrated using cumulus and cirrus clouds * Lidar cloud slicing was validated with in situ measurements
ISSN:0094-8276
1944-8007
DOI:10.1002/2014GL062749