南亚高压对青藏高原臭氧谷的动力作用

The dynamic effects of the South Asian high on the ozone valley over the Tibetan Plateau

中文关键词:  青藏高原臭氧谷， 南亚高压， 季节演变， 动力作用

英文关键词:Ozone valley over the Tibetan Plateau, South Asian high, Seasonal variation, Dynamic effects

中文摘要:

      利用臭氧观测光谱仪/太阳紫外线后向散射仪（TOMS/SBUV）的臭氧总量资料和SAGE Ⅱ臭氧廓线资料计算了青藏高原区纬向偏差（一个量减去该量的纬圈平均值，定义为该量的纬向偏差）臭氧总量的逐月变化和高原区150—50 hPa高度纬向偏差臭氧量的变化，二者相关显著，相关系数为0.977。由于在150—50 hPa高度，夏季青藏高原臭氧谷最强，南亚高压最活跃，因此，青藏高原臭氧谷与南亚高压可能存在联系。在运行WACCM3模式时，将青藏高原地形高度削减至1500 m，在150—50 hPa高度南亚高压和青藏高原臭氧谷仍存在；该高度上南亚高压强度变小，青藏高原臭氧谷也减弱；南亚高压季节移动发生改变，青藏高原臭氧谷季节变化也随之改变。因此，推测南亚高压可能对青藏高原臭氧谷有重要作用。接着分析了模式输出的青藏高原区经向、纬向和垂直方向的臭氧输送。在南亚高压季节变化的不同阶段和不同方向上，环流对青藏高原臭氧谷的作用明显不同。150—50 hPa，南亚高压上高原时，纬（经）向输送使青藏高原臭氧谷加深（变浅），垂直输送在低（高）层使青藏高原臭氧谷加深（变浅），总的动力作用使青藏高原臭氧谷减弱；南亚高压稳定在高原上空时，纬（经）向输送使青藏高原臭氧谷变浅（加深），垂直输送在中（底和顶）层使青藏高原臭氧谷加深（变浅），总的动力作用使青藏高原臭氧谷加深；在南亚高压从高原撤退时，纬（经）向作用使青藏高原臭氧谷加深（变浅），垂直作用使青藏高原臭氧谷变浅，总的动力作用使青藏高原臭氧谷中（底和顶）层加深；当南亚高压移至热带太平洋时，南亚高压对高原区臭氧影响较弱。

英文摘要:

      In this study, the TOMS/SBUV (Total Ozone Mapping Spectrometer/Solar Backscatter Ultraviolet Radiometer) data and SAGE (Stratospheric Aerosol and Gas Experiment) II data were employed to calculate the monthly total ozone deviations over the Tibetan Plateau and the 150-50 hPa zonal ozone variations. The results show that there is a significant correlation between these two, with a correlation coefficient of 0.977. From 150 to 50 hPa, the ozone valley over the Tibetan Plateau (OVTP) becomes the strongest based on the SAGE II data, and the South Asian high (SAH) is the most active according to the 40-year reanalysis data of the European Centre for Medium Range Weather Forecasts (ERA-40), so a correlation between the SAH and the OVTP may exist. The WACCM3 (Whole Atmosphere Community Climate Model version 3) simulations with the height of the Tibetan Plateau cut down to 1500 m also show that the seasonal variation of SAH would result in a matched seasonal variation of the OVTP, which suggests a meaningful effect of the OVTP, depending on the SAH’s evolution stages and movement directions. At 150-50 hPa, as the SAH approaches the plateau, the SAH zonal (meridional) transport would make the OVTP deeper (shallower), combined dynamic effects lead to a weakened OVTP. When the SAH stabilizes over the Tibetan Plateau, the zonal (meridional) transport results in a shallower (deeper) OVTP while the vertical transport would create a deeper (shallower) OVTP at the middle (bottom and top) levels; the combined dynamic effects produce a deeper OVTP. As the SAH retreats from the Tibetan Plateau, the OVTP becomes deeper (shallower) due to the zonal (meridinal) effect or shallower due to the vertical effect; the combined dynamic effects contribute to a deeper (shallower) OVTP at the middle (bottom and top) levels. The SAH would have a weak effect on the OVTP over the Tibetan Plateau when it positioned over the tropical Pacific.