Differences in the fractions of ice clouds between eastern and western parts of Eurasian continent using CALIPSO in January 2007

摘要

We investigated the difference in the fraction of ice (water) cloud bins between eastern and western parts of Eurasia using Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data in January 2007. The fraction of ice cloud bins between ?25 and 0 °C was clearly larger in eastern Eurasia than in western Eurasia. A significantly increased (about 20–30%) fraction of ice‐containing clouds is observed in eastern Eurasia in the cloud top temperatures range from ?30 to ?15 °C. The difference in ice cloud bin fractions between eastern and western Eurasia was remarkable between ?20 and ?5 °C, being about 20% greater in eastern Eurasia. The fraction of ice cloud bins in the lower troposphere (below 3 km) was larger in eastern Eurasia than in western Eurasia. These results indicate that the ice formation process was more promoted in the lower troposphere in eastern Eurasia than in western Eurasia. This is the first time such results have been obtained from cloud internal structure observations using the CALIPSO active sensor. Northern Hemisphere distribution in January 2007 of: (a) fraction of ice cloud bins between ?25 and 0 °C, (b) fraction of water cloud bins between ?25 and 0 °C, (c) the total sample numbers of (a) and (b), (d) fraction of clouds in the whole sky, (e) net surface long‐wave radiation, (f) temperature 2 m above ground, and (g) the mean height of ice cloud bins with temperatures of 0 to ?25 °C, (h) same as (g) but for water cloud bins. (a)–(d), (g), and (h) are from Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data, with a resolution of 3.0° latitude by 3.0° longitude. (e) and (f) are from Japanese 55‐year reanalysis (JRA‐55) data, with a resolution of 1.25° latitude by 1.25° longitude.