Transport of low ozone air masses to South America middle latitudes: impact on solar UV irradiances
Transport of low ozone air masses to South America middle latitudes: impact on solar UV irradiances
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低臭氧气团向南美洲中纬度地区输送：对太阳紫外线辐照度的影响
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发表时间：
2016
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影响因子：
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通讯作者：
A. Mizuno
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作者：
E. Wolfram;P. F. Orte;J. Salvador;A. Pazmino;S. Godin‐Beekmann;E. Quel;H. Akiyoshi;T. Sugita;A. Mizuno
南半球的副极地地区受到臭氧总量短期低值的影响，臭氧总量低值与臭氧空洞的过度直接相关。这些事件经常发生在春季和初夏，臭氧层不足的空气的极地火焰向北传播到低纬度地区，如布宜诺斯艾利斯（34 S）。
在这些事件中，副极地地区经历了一个显着的臭氧减少，一般增强UV-B辐射，这取决于云层覆盖情况。但地表紫外辐射水平不仅取决于臭氧总柱（TOC）。太阳天顶角（SZA）、云量、气溶胶含量和地面湿度也起着重要的作用。
在极地臭氧贫乏的气团向低纬度地区输送的过程中，中午臭氧含量低和太阳高度高的组合可引起地面辐照度相对于气候条件的变化，低纬度地区的紫外线指数高于高纬度地区。
在本文中，我们评估增加的紫外线指数在这种情节使用参数紫外线模型，作为输入参数TOC从OMI/AURA和计算中午太阳天顶角为三个选定的网站在这项研究中考虑：里约加列戈斯（51 S），科莫多罗里瓦达维亚（45 S）和布宜诺斯艾利斯（34 S）。本文选取了NCEP再分析的550 K等熵位涡图作为极涡扰动的示踪剂，分析了极涡扰动的演变过程。
利用多传感器再分析（MRS）（1978-2013）的臭氧气候数据库，模拟了中午紫外辐射水平，并计算了输送到副极地地区的贫臭氧气团对地面辐射水平的相对影响。
结果表明，臭氧质量较差的空气输送到中纬度地区，增加了紫外辐射水平，与低纬度地区太阳正午较高的太阳高度相结合，对太阳紫外辐射产生了较大的影响。
The subpolar regions of the Southern Hemisphere are affected by short periods of low total ozone values directly linked to overpasses of the ozone hole. These events often happen during spring and early summer time and the polar flames of ozone poor air travel northward to low latitudes as much as Buenos Aires ( 34 S).
During these episodes, the subpolar regions experience a pronounced ozone reduction with generally an enhance- ment of UV-B radiation, depending on cloud cover conditions. But the level of surface UV radiation not only depends of total ozone column (TOC). Also play an important role the solar zenith angle (SZA), the cloud cover, the aerosols loading and the surface albedo.
The combination of low ozone content and high solar elevations at noon during the transports of polar ozone poor airmasses to lower latitudes can induce a relative change of surface irradiance respect to climatological conditions with greater UV indexes at lower than in the higher latitudes.
In this paper we evaluate the increase of UV index at surface during this kind of episodes using a parametric UV model that use as input parameters TOC from OMI/AURA and calculated noon solar zenith angle for three selected sites considered in this study: Rio Gallegos ( 51S), Comodoro Rivadavia (45S) and Buenos Aires (34S). The study cases analyzed in this work were selected using potential vorticity maps at isentropic level of 550 K form NCEP reanalysis as tracer of the perturbation of polar vortex.
By means of ozone climatological database of Multi Sensor Reanalysis (MRS) (1978-2013) for the selected sites we modeled the climatological UV radiation level at noon time and calculate the relative impact that induces the transported ozone poor airmasses to subpolar regions on surface radiation levels.
The results show that the poor ozone airmass transported to middle latitudes increase the UV radiation level and the combination with higher solar elevation at solar noon at lower latitudes induce a high impact in the solar UV radiation.