Through a comprehensive analysis, researchers from the CAS Institute of Atmospheric Physics (IAP) discovered an ozone minihole, a large area with the lowest total ozone column (TOC, see figure), over the Qinghai-Tibet Plateau from Dec. 14 to 17, 2003. The area with TOC less than 220 DU is over 250 square kilometers with its central lowest value of 190 DU, about 25% reduction from the historical average value in this region.
Based on analysis of ground-based observation data obtained by Brewer ozone spectrophotometer at the Waliguanshan Station WANG Gengchen from IAP and QI Donglin from the Qinghai Provincial Meteorological Administration first found the record with unusually low TOC during mid-December in 2003. Based on this, BIAN Jianchun and colleagues from IAP discovered the ozone minihole event over the Qinghai-Tibet Plateau two years ago through a comprehensive analysis on the data from ground-based, satellite and meteorological observations. They also show that the major reason behind the event is a weather process.
The ozone hole over the Antarctic, stratospheric ozone depletion, and its possible impacts on climate-environment-ecosystem changes have become issues of concern in today's world. Chinese researchers have kept tracking of ozone changes over the Plateau and carried out a series of research work. ZHOU Xiuji and ZOU Han have discovered an ozone valley (a center of ozone depletion) over the Tibetan Plateau in the summers of 1994 and 1996, respectively.
