1. Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
2. Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
3. Institute of Surface-Earth System Science, Tianjin University, Tianjin 300072, China
4. Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana 47907, United States