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Lidar Observations of Atmospheric CO2 Column During 2014 Summer Flight CampaignsAdvanced knowledge in atmospheric CO2 is critical in reducing large uncertainties in predictions of the Earth' future climate. Thus, Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) from space was recommended by the U.S. National Research Council to NASA. As part of the preparation for the ASCENDS mission, NASA Langley Research Center (LaRC) and Exelis, Inc. have been collaborating in development and demonstration of the Intensity-Modulated Continuous-Wave (IM-CW) lidar approach for measuring atmospheric CO2 column from space. Airborne laser absorption lidars such as the Multi-Functional Fiber Laser Lidar (MFLL) and ASCENDS CarbonHawk Experiment Simulator (ACES) operating in the 1.57 micron CO2 absorption band have been developed and tested to obtain precise atmospheric CO2 column measurements using integrated path differential absorption technique and to evaluate the potential of the space ASCENDS mission. This presentation reports the results of our lidar atmospheric CO2 column measurements from 2014 summer flight campaign. Analysis shows that for the 27 Aug OCO-2 under flight over northern California forest regions, significant variations of CO2 column approximately 2 ppm) in the lower troposphere have been observed, which may be a challenge for space measurements owing to complicated topographic condition, heterogeneity of surface reflection and difference in vegetation evapotranspiration. Compared to the observed 2011 summer CO2 drawdown (about 8 ppm) over mid-west, 2014 summer drawdown in the same region measured was much weak (approximately 3 ppm). The observed drawdown difference could be the results of the changes in both meteorological states and the phases of growing seasons. Individual lidar CO2 column measurements of 0.1-s integration were within 1-2 ppm of the CO2 estimates obtained from on-board in-situ sensors. For weak surface reflection conditions such as ocean surfaces, the 1- s integrated signal-to-noise ratio (SNR) of lidar measurements at 11 km altitude reached 376, which was equivalent to a 10-s CO2 error 0.33 ppm. For the entire processed 2014 summer flight campaign data, the mean differences between lidar remote sensed and in-situ estimated CO2 values were about -0.013 ppm. These results indicate that current laser absorption lidar approach could meet space measurement requirements for CO2 science goals.
Document ID
20160006490
Acquisition Source
Langley Research Center
Document Type
Presentation
Authors
Lin, Bing (NASA Langley Research Center Hampton, VA, United States)
Harrison, F. Wallace (NASA Langley Research Center Hampton, VA, United States)
Fan, Tai-Fang (Science Systems and Applications, Inc. Seabrook, MD, United States)
Date Acquired
May 23, 2016
Publication Date
June 16, 2015
Subject Category
Meteorology And Climatology
Report/Patent Number
NF1676L-21637
Meeting Information
Meeting: International Workshop on Greenhouse Gas Measurements from Space (IWGGMS-11)
Location: Pasadena, CA
Country: United States
Start Date: June 16, 2015
End Date: June 18, 2015
Sponsors: California Inst. of Tech.
Funding Number(s)
WBS: WBS 304029.01.04.05.02
Distribution Limits
Public
Copyright
Public Use Permitted.

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