基于ERA5月平均再分析资料,利用Lorenz环流分解方法从定常和瞬变以及基流和涡旋的角度对比了北极与青藏高原臭氧低值区的动力输送特征.结果表明:动力总输送在两地上平流层作用最强,均使其臭氧浓度降低,且定常输送均强于瞬变输送,纬向与经向输送的作用均大致相反.然而,动力输送在北极地区的作用强度远大于青藏高原地区.北极地区纬向输送使得平流层中上层臭氧浓度降低,平流层下层臭氧浓度升高,经向输送的作用与之相反且强度明显偏弱,二者均主要作用于上平流层.青藏高原地区纬向和经向输送除在上平流层均使得臭氧浓度降低外,二者作用大致相反且强度相当,输送大值区在垂直方向上存在双中心结构,分别位于上平流层与上对流层—下平流层(Upper Troposphere-Lower Stratosphere,简称UTLS)区.两地区纬向和经向输送的差异均主要由定常涡旋输送所造成.青藏高原地区定常与瞬变输送的强度差异没有北极地区大.此外,两地定常和瞬变输送中涡旋对臭氧纬向平均的输送均起到主要作用,体现出涡旋输送在两地臭氧浓度变化的动力输送过程中发挥着至关重要的作用.

We studied the effects of the stationary and transient transport of ozone in the upper troposphere and lower stratosphere (UTLS) on the ozone valley over the Tibetan Plateau (OVTP) in summer using the daily ERA-Interim reanalysis dataset for the time period 1979–2016. We used the Lorenz circulation decomposition method to separate the stationary and transient transport of ozone into terms related to either the mean flow or eddies. The decrease in the total ozone concentration in summer is associated with the transport of ozone, which, in turn, reinforces the OVTP. The zonal (meridional) transport of ozone, which combines stationary and transient transport, strengthens (weakens) the ozone valley. The stationary zonal (meridional) transport of ozone strengthens (weakens) the ozone valley. The transient zonal (meridional) transport of ozone weakens (strengthens) the ozone valley, but this effect is weaker than that of stationary transport. The mean flow has the dominant role, especially in the stationary component. The effect of eddies on the zonal transient transport of ozone is as strong as that of the mean flow. For stationary transport, the zonal deviation of ozone transported by the zonal mean flow in the zonal (meridional) direction C(O3∗¯ [u]¯)(C(O3∗¯ [v]¯)) dominates total zonal (meridional) change of ozone C(O3¯ u¯)(C(O3¯ v¯)) , which strengthens (weakens) the ozone valley. The transient transport of the zonal mean ozone by eddies (C([O3]′u∗′¯)) , the zonal deviation of ozone by the zonal mean flow (C(O3∗′[u]′¯)) and the zonal deviation of ozone by eddies (C(O3∗′u∗′¯)) all have a strong effect on the ozone valley. By contrast, the transient transport of the zonal mean ozone by eddies in the meridional direction (C([O3]′v∗′¯)) has a much weaker and the smallest effect. Both the zonal deviation of ozone by the zonal mean flow and by eddies in the meridional direction (C(O3∗′[v]′¯) and C(O3∗′v∗′¯)) have major roles in transient meridional transport, but their roles are the opposite of each other. The contributions of stationary and transient transport to zonal transport are consistent, whereas their contributions to meridional transport are the opposite of each other. The influence of transient transport on the formation and maintenance of OVTP is not negligible.

Using four satellite data sets（TOMS/SBUV, OMI, MLS, and HALOE）, we analyze the seasonal variations of the total column ozone（TCO） and its zonal deviation（TCO*）, and reveal the vertical structure of the Ozone Low（OV） over the Asian continent. Our principal findings are:（1） The TCO over the Asian continent reaches its maximum in the spring and its minimum in the autumn. The Ozone Low exists from May to September.（2） The Ozone Low has two negative cores, located in the lower and the upper stratosphere. The lower core is near 30 hPa in the winter and 70 hPa in the other seasons. The upper core varies from 10 hPa to 1 hPa among the four seasons.（3）The position of the Ozone Low in the lower and the upper stratosphere over the Asian continent shows seasonal variability.

利用1979-2016年ERA-interim逐日再分析资料,定义了青藏高原臭氧谷(Ozone Valley over the Tibetan Plateau,OVTP)极端和普通强(弱)事件,并讨论了其特征.结果表明:1)OVTP极端强事件在夏秋季节多发,10月最多,频率达2.0％;OVTP普通强事件在春夏季多发,7月最多,频率达1.7％.OVTP极端弱事件在秋冬季多发,12月最多,频率达3.8％;OVTP普通弱事件在冬季多发,1月最多,频率达2.0％.2) OVTP极端强事件出现频率显著增加(0.004％·a-1),极端弱事件出现频率显著减少(-0.015％·a-1).OVTP普通事件的变化均不显著.3)OVTP极端强事件的面积和强度均在秋季最大,10月达到最大值,面积为4.3×105 km2,强度为1.5×05 t;OVTP普通强事件的面积和强度均在夏季最大,7月达到峰值,面积为1.7×105 km2,强度为4.1×103t.OVTP极端弱事件的面积和强度在春夏较小,4月达到最小值,面积为3.2×104 km2,强度为1.1×102 t;OVTP普通弱事件的面积和强度在春夏秋均较小,4月和10月达到极小值,4月面积为2.5× 104km2,强度为68 t,10月面积为2.2× 104km2,强度为97 t.4) OVTP极端和普通强事件的面积(强度)均呈显著增大(增强)趋势,极端强事件的面积达2.5×102 km2·a-1,强度达2.5×102 t·a-1,普通强事件的面积达4.5×102km2·a-1,强度达4.5t.a-1.极端和普通弱事件的面积(强度)均呈显著减小(减弱)趋势,极端弱事件的面积达-1.7×104 km2·a-1,强度达-7.0× 103 t·a-1,普通弱事件的面积达-2.3×103 km2·a-1,强度达-2.7×102 t·a-1.