1. School of Natural Resource Sciences, Center for Laser‐Analytical Studies of Trace Gas Dynamics, 244 LW. Chase Hall, PO Box 830728, University of Nebraska, Lincoln, NE 68583‐0728, USA,
2. Global Environment Laboratory, Department of Atmospheric Sciences, Yonsei University, Seoul 120–749, Korea,
3. Center for Laser‐Analytical Studies of Trace Gas Dynamics, Department of Electrical Engineering, University of Nebraska, Lincoln, NE 68583–0511, USA