Special issue  

Measurements of water vapor in the upper troposphere and lower stratosphere are essential to understanding the role of water vapor in climate change and stratospheric ozone depletion and recovery. The MOHAVE-2009 campaign took place at the Jet Propulsion Laboratory Table Mountain Facility (California) in October 2009. The campaign hosted a large number of instruments and techniques which allowed intensive measurements of water vapor mixing ratio between the ground and the mesopause, as well as total precipitable water (TPW). Six ground-based lidars from three different research groups provided over 350h of water vapor, ozone, and temperature measurements. Over 50 balloons were launched with RS92 PTU sondes on board. Twenty of them included frost-point hygrometers (FPHs), allowing thorough validation of the lidar measurements.

The water vapor profiles obtained from the JPL lidar showed no systematic bias with the FPH up to 20km. One-hour time integration allowed the JPL profiles to reach 14–15km, and 50-hour averages allowed the profiles to reach 20km with approximate 20% precision. Outstanding water vapor–ozone correlations were observed and revealed a major stratospheric intrusion on October 20. Two GPS receivers, two microwave radiometers, and two Fourier transform spectrometers provided near-continuous measurements of TPW. Excellent agreement between all instruments was found, suggesting that these techniques can become important complements to the radiosonde for routine lidar calibration.

An estimated six to nine manuscripts will be submitted. The first one (by T. Leblanc et al.) will be an overview of the campaign operations, measurements, and results. Three manuscripts will focus on the lidar measurements (T. McGee et al., D. Whiteman et al., and S. McDermid et al.). One manuscript will be dedicated to the results from balloon measurements (D. Hurst et al.). One manuscript will review the total precipitable water measurements. One manuscript will focus on the results from the ground-based Fourier transform spectrometer (G. Toon et al.). Finally, one paper will cover the satellite measurements, especially those from ENVISAT/MIPAS (G. Stiller et al.). An optional submission (by T. Leblanc) will cover the case study of a stratospheric intrusion.