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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union
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Volume 5, issue 11
Atmos. Meas. Tech., 5, 2893–2916, 2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue: Validation of water vapor measurements during MOHAVE-2009

Atmos. Meas. Tech., 5, 2893–2916, 2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 28 Nov 2012

Research article | 28 Nov 2012

Correction technique for Raman water vapor lidar signal-dependent bias and suitability for water vapor trend monitoring in the upper troposphere

D. N. Whiteman1, M. Cadirola2, D. Venable3, M. Calhoun3, L. Miloshevich4, K. Vermeesch5, L. Twigg5, A. Dirisu6, D. Hurst7, E. Hall7, A. Jordan7, and H. Vömel8 D. N. Whiteman et al.
  • 1NASA/GSFC, Greenbelt, MD 20771, USA
  • 2Ecotronics, LLC, Clarksburg, MD 20871, USA
  • 3Howard University, Washington, DC 20059, USA
  • 4Milo Scientific, LLC, Lafayette, CO 80026, USA
  • 5SSAI, Lanham, MD 20706, 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, 80305, Colorado, 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 (Atmospheric Laboratory for Validation, Interagency Collaboration and Education) mobile laboratory in the MOHAVE-2009 campaign. In appendices we also report on the performance of the corrected Vaisala RS92 radiosonde measurements during the campaign, on a new radiosonde based calibration algorithm that reduces the influence of atmospheric variability on the derived calibration constant, and on other results of the ALVICE deployment. The MOHAVE-2009 campaign permitted the 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. Other sources of wet biases are discussed and data from other Raman lidar systems are investigated, revealing that wet biases in upper tropospheric (UT) and lower stratospheric (LS) 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 bias. A correction technique is derived and applied to the ALVICE lidar water vapor profiles. Good agreement is found between corrected ALVICE lidar measurments and those of RS92, frost point hygrometer and total column water. 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 robust. The correction shown here holds promise for permitting useful upper tropospheric water vapor profiles to be consistently measured by Raman lidar within NDACC (Network for the Detection of Atmospheric Composition Change) 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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