1. CAS Key Laboratory of Geospace Environment; Department of Geophysics and Planetary Science; University of Science and Technology of China; Hefei China
2. Atmospheric Chemistry Division and Advance Study Program; National Center for Atmospheric Research; Boulder Colorado USA
3. Now at Departamento Fisica de la Tierra II; Universidad Complutense de Madrid; Madrid Spain
4. Center for Atmospheric Sciences; Hampton University; Hampton Virginia USA
5. NASA Langley Research Center; Hampton Virginia USA
6. Department of Physics; Colorado State University; Fort Collins Colorado USA