Clear Skies and Huge Thunderclouds More Frequent in East Asia

Clear skies became more frequent in East Asia over the period between 1971 and 1996, but enormous cumulonimbus clouds that bring torrential rains also develop more often, indicating the possible influence of human activities on global warming. These findings were announced by governmental research institute the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) on March 29, 2006.

Dr. Tetsuzo Yasunari, Director of the Hydrological Cycle Research Program of the Frontier Research Center for Global Change at JAMSTEC, and Dr. Nobuhiko Endo, a JAMSTEC researcher, analyzed long-term ground-based cloud observation data that had been collected visually at meteorological stations. According to their analysis from 1971 to 1996, the frequency of clear skies in summer increased across China, while the frequency of cumulus clouds decreased. In southern China, a decrease was observed in the occurrence of cumulonimbus clouds, which are believed to bring heavy rains; however, such clouds increased in volume and tended to develop into powerful thunderclouds in recent years, making the area more susceptible to downpours.

The study was the first in the world to clarify such trends in cloud cover variations in East Asia. Its results provide new and significant meteorological information on global warming, a topic much debated by the Intergovernmental Panel on Climate Change (IPCC), and on the changes in processes of hydrological cycles associated with increases in atmospheric aerosols and land use change in East Asia. The information can also be useful to evaluate climate model performance and to improve the reliability of climate projections in East Asia. The report was published in the April issue of the Journal of Climate of the American Meteorological Society.

http://ams.allenpress.com/amsonline/?request=get-document&doi=10.1175%2FJCLI3679.1

Posted: 2006/06/25 10:44:30 PM
Japanese version