[Variation of total ozone over Tibetain Plateau during 30 years monitored by remotely sensed data]

This paper is study on the temporal and spatial dynamics characteristics of total ozone over Tibetain Plateau from 1979 using multi-resource remote sensing. The findings indicate that the total ozone over Tibetain Plateau is continuously decreasing. The decreasing rate is larger than the global and northern hemisphere average, and the average annual decreasing rates are about 0.23%, 0.19% and 0.12% for Tibetain Plateau, global and northern hemisphere average respectively. However, the decreasing rate is lessening after 2000. The decreasing rates each year are about 0.51%, 0.49% and 0.31% during the 3 stages of 1979-1989, 1990-1999 and 2000-2008. The days of total ozone over Tibetain Plateau lower than 240 DU is up to 34 d, and there is not largely lower ozone (lower than 240 DU) area after 2005; the seasonal variation of total ozone present sinusoidal, the largest and smallest value appear in March and October, the average values are about 304.59 and 265.45 DU respectively. But the smallest of daily value are often appears in November or December. The largest and smallest fluctuation of total ozone appear in February and September with the standard deviation of 17.28 and 5.88 DU respectively; the total ozone and altitude is inversely relationship, lower ozone appear over higher altitude areas, especially, over Tibetain Plateau region. Compare with the average total ozone over the same latitude, the total ozone over Tibetain Plateau is lower with about 19 DU, and give birth to an ozone valley.