Determination of Cirrus Occurrence and Distribution Characteristics Over the Tibetan Plateau Based on the SWOP Campaign
- 1College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
- 2Institute of Atmospheric Physics, Chinese Academy of Sciences, Key Laboratory of Middle Atmosphere and Global Environment Observation, Beijing, China (lidan@mail.iap.ac.cn)
- 3College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- 4State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, China Meteorological Administration, Beijing, China
- 5Earth Observation Laboratory, National Center for Atmospheric Research, Boulder, CO, USA
- 6Institute for Atmospheric and Climate Science (IAC), Swiss Federal Institute of Technology (ETH), Zürich, Switzerland
- 7Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO, USA
- 8National Oceanic and Atmospheric Administration Earth System Research Laboratory, Global Monitoring Division, Boulder, CO, USA
- 9College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
Balloon sounding with the Compact Optical Backscatter Aerosol Detector (COBALD) and Frost Point hygrometers (FPs) provides in situ data for a better understanding of the vertical distribution of cirrus clouds. In this study, eight summer balloon-borne measurements in Kunming (2012, 2014, 2015, and 2017) and Lhasa (2013, 2016, 2018, and 2020) over the Tibetan Plateau were used to show the distribution characteristics of cirrus clouds. Differences of cirrus occurrence were compared by different indices: the backscatter ratio (BSR) at a 455 nm/940 nm wavelength (BSR455 > 1.2/BSR940 > 2), the color index (CI > 7), and the relative humidity with respect to ice (RHice > 70%). Analysis of the profiles indicated that BSR455 > 1.2 was the optimal criterion to identify the cirrus layer and depict the distribution of the CI and RHice within cirrus clouds. The results showed that the median CI (RHice) within the cirrus clouds at both sites was mostly in the 18–20 (90%–110%) range at pressures below 120 hPa. Furthermore, the balloon-borne measurements combined with Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) measurements indicated a high frequency of cirrus occurrence near the tropopause in Kunming and Lhasa. The top height of cirrus occurrence at both sites was above the cold point tropopause and the lapse rate tropopause. Both Kunming and Lhasa had the highest frequency of thin cirrus clouds in the 0–0.4 km vertical cirrus thickness range.
How to cite: Yang, Z., Li, D., Luo, J., Tian, W., Bai, Z., Li, Q., Zhang, J., Wang, H., Zheng, X., Vömel, H., Wienhold, F. G., Peter, T., Hurst, D., and Bian, J.: Determination of Cirrus Occurrence and Distribution Characteristics Over the Tibetan Plateau Based on the SWOP Campaign, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7972, https://doi.org/10.5194/egusphere-egu24-7972, 2024.
