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www.atmos-meas-tech-discuss.net/4/7337/2011/
doi:10.5194/amtd-4-7337-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
Correction technique for raman water vapor lidar signal dependent bias and suitability for water vapor trend monitoring in the upper troposphere
1NASA/GSFC, Greenbelt, MD 20771, USA
2Ecotronics, LLC, Clarksburg, MD 20871, USA
3Howard University, Washington, DC, USA
4Milo Scientific, LLC, Lafayette, CO 80026, USA
5SSAI, Lanham, MD, USA
6Oak Ridge Associated Universities, Oak Ridge, 37381, TN, USA
7Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309 and NOAA Earth System Research Laboratory, Global Monitoring Division, Boulder, Colorado 80305, USA
8Lindenberg Observatory, Lindenberg, Germany
Abstract. The MOHAVE-2009 campaign brought together diverse instrumentation for measuring atmospheric water vapor. We report on the participation of the ALVICE mobile laboratory in the MOHAVE-2009 campaign. In an appendix we also report on the performance of the corrected Vaisala RS92 radiosonde during the campaign. A new radiosonde based calibration algorithm is presented that reduces the influence of atmospheric variability on the derived calibration constant. The MOHAVE-2009 campaign permitted all Raman lidar systems participating to discover and address measurement biases in the upper troposphere and lower stratosphere. The ALVICE lidar system was found to possess a wet bias which was attributed to fluorescence of insect material that was deposited on the telescope early in the mission. A correction technique is derived and applied to the ALVICE lidar water vapor profiles. Other sources of wet biases are discussed and data from other Raman lidar systems are investigated revealing that wet biases in upper tropospheric and lower stratospheric water vapor measurements appear to be quite common in Raman lidar systems. Lower stratospheric climatology of water vapor is investigated both as a means to check for the existence of these wet biases in Raman lidar data and as a source of correction for the data. The correction is offered as a general method to both quality control Raman water vapor lidar data and to correct those data that have signal-dependent bias. The influence of the correction is shown to be small at regions in the upper troposphere where recent work indicates detection of trends in atmospheric water vapor may be most resistant to additional noise sources. The correction shown here holds promise for permitting useful upper tropospheric water vapor profiles to be consistently measured by Raman lidar within NDACC and elsewhere despite the prevalence of instrumental and atmospheric effects that can contaminate the very low signal to noise measurements in the UT.
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Citation: Whiteman, D. N., Cadirola, M., Venable, D., Calhoun, M., Miloshevich, L., Vermeesch, K., Twigg, L., Dirisu, A., Hurst, D., Hall, E., Jordan, A., and Vömel, H.: Correction technique for raman water vapor lidar signal dependent bias and suitability for water vapor trend monitoring in the upper troposphere, Atmos. Meas. Tech. Discuss., 4, 7337-7403, doi:10.5194/amtd-4-7337-2011, 2011. Bibtex EndNote Reference Manager XML
