50年来中国臭氧总量时空变化特征

利用来自世界臭氧与紫外辐射数据中心的中国区域6个地基观测站点数据,对多传感器再分析遥感数据进行验证,并基于验证后的遥感数据分析了1971~2020年中国区域臭氧总量不同尺度的时空变化特征.结果表明,50a来中国区域臭氧总量呈现轻微的下降趋势.年平均臭氧总量在1978年和1993年分别出现最大值(347.5±53.8) DU和最小值(291.9±29.5) DU,在1971~1978年、1978~1993年、1993~2020年,这3个时段年平均臭氧总量在整个中国区域分别是增长、减少、增长.月平均臭氧总量随季节变化呈现出正弦曲线形态,在3月和10月分别出现峰值(约338DU)和谷值(约285DU).中国区域臭氧总量在空间上呈现由东北向西南递减的纬向条带状分布.在40°N以北的东北部地区,该值可达360DU以上.中国区域50a月平均臭氧总量同样呈现纬向条带状分布.此外,时间变异系数和空间变异系数随季节的变化规律相似,夏季最小,接着依次是秋季和春季,冬季最大.即臭氧总量的变化和空间差异在夏季都最小.50a期间,不同时段、不同区域臭氧总量的变化趋势各不相同.在1971~1978年,臭氧总量的增长量和增长率都呈现由北向南递减的纬向条带状分布.在40°N以北的相对高值地区最大增加了56DU,约为16%;而在30°N以南的相对低值地区,最小增加了12DU,约为5%.在1978~1993年,减少量和减少率也呈现由北向南递减的纬度地带性.在40°N以北的相对高值地区最大减少了93DU,约为22%;而在30°N以南的相对低值地区,最小减少了11DU,约为4%.在1993~2020年,西北地区出现最大增长,增长量为18DU,约为6%;东南地区出现最小增长,增长量为4DU,约为1%.

Investigating the temporal and spatial variabilities of total ozone over China for the past 50 years

Based on the Multi-Sensor Reanalysis version 2data, which was validated by the data from 6ground-based observation stations belonging to the World Ozone and Ultraviolet Radiation Data Centre, this study analyzed the temporal and spatial variabilities of total ozone over China for the period 1971~2020. It was found that the total ozone over China showed a slight downward trend in the past 50years. The annual mean total ozone reached a maximum value of (347.5 ±53.8) DU in 1978 and a minimum one of (291.9 ±29.5) DU in 1993. In the three sub-periods, 1971~1978, 1978~1993, and 1993~2020, the annual mean total ozone over China completely increased, decreased, and increased, respectively. The seasonal variability of the monthly mean total ozone presented a sinusoidal wave with a maximum value of about 338DU in March and a minimum value of about 285DU in October. The spatial distribution of the annual mean total ozone over China in the past 50years showed a latitudinal pattern by decreasing gradually from northeast areas to southwest areas. Moreover, the values could be greater than 360DU in the northeast China with latitudes over 40°N. The spatial distribution of monthly mean total ozone also showed a latitudinal pattern. In addition, the temporal and spatial variation coefficients showed similar seasonal variability, with the minimum value in summer, followed by the values in autumn, spring, and winter. Namely, the variability of total ozone and its spatial difference was minimum in summer. Finally, the trend of total ozone varied with periods and areas in the past 50years. During the period 1971~1978, the increase value and rate of annual mean total ozone showed a latitudinal pattern by decreasing gradually from north areas to south areas. In the areas with relatively high annual mean total ozone, such as the north China with latitude over 40°N, the maximum increase value was 56DU, around 16%. Yet, in the areas with relatively low annual mean total ozone, such as the south China with latitude below 30°N, the minimum increase value was 12DU, around 5%. During the period 1978~1993, the decreased value and rate of annual mean total ozone also showed a latitudinal pattern. In the areas with relatively high annual mean total ozone, such as the north China with latitudes over 40°N, the maximum decrease value was 93DU, around 22%. Yet, in the areas with relatively low annual mean total ozone, such as the south China with latitude below 30°N, the minimum decrease value was 11DU, around 4%. During the period 1993~2020, the maximum increase value (18DU, about 6%) was found in the northwest areas. In contrast, the minimum increase value (4DU, about 1%) was found in the southeast areas.