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首页> 外文期刊>Theoretical and applied climatology >Reconstruction of erythemal UV irradiance and dose at Hohenpeissenberg (1968-2001) considering trends of total ozone, cloudiness and turbidity
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Reconstruction of erythemal UV irradiance and dose at Hohenpeissenberg (1968-2001) considering trends of total ozone, cloudiness and turbidity

机译：考虑到总臭氧，浑浊和浑浊的趋势，在Hohenpeissenberg（1968-2001）重建红斑紫外线辐射和剂量

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Erythemal ultraviolet (UV) doses reaching the earth's surface depend in a complex manner on the amount of total ozone, cloud cover, cloud type and the structure of the cloud field, A statistical model was developed allowing the reconstruction of UV from measured total ozone and a cloud modification factor (CMF) for the GAW site Hohenpeissenberg, Germany (48°N, 11°E). CMF is derived from solar global radiation G, normalized against a Rayleigh scattering atmosphere. By this way the complex influence of the cloud field is accounted for by introduction of a measured parameter, exposed also to this complex field. The statistical relations are derived from the period 1990-1998 where UV measurements and relevant meteorological parameters are available. With these relations daily UV doses could be reconstructed back to 1968. Tests show that the model works remarkably well even for time scales of a minute except for situations with high albedo. The comparison of measured and calculated UV irradiances shows that the model explains 97% of the variance for solar elevations above 18° on average over the period 1968-2001. The reconstruction back to 1968 indicates that maximum UV irradiances (clear days) have increased due to long-term ozone decline. Clouds show seasonally depending long-term changes, especially an increase of cirrus. Consequently the UV doses have increased less or even decreased in some months in comparison to the changes expected from the ozone decline alone. In May to August total cloud frequency and cloud cover have decreased. Therefore, the average UV doses have increased much more than can be explained by the ozone decline alone. It is also shown that the optical thickness of cirrus clouds has increased since 1953. The higher frequency of cirrus is caused in part by more frequent contrails. Besides that an observed long-term rise and cooling of the tropopause favors an easier cirrus formation. However, whether climate change and an intensification of the water cycle is responsible for the cirrus trends has not been investigated in detail.
机译：到达地球表面的紫外紫外线剂量以复杂的方式取决于总臭氧量，云量，云的类型和云场的结构。开发了一个统计模型，可以从测得的总臭氧中重建紫外线。 GAW站点德国Hohenpeissenberg的云修正因子（CMF）（北纬48°，东经11°）。 CMF来自太阳总辐射G，针对瑞利散射大气进行归一化。以此方式，通过引入也暴露于该复杂场的测量参数来解决云场的复杂影响。统计关系是从1990-1998年期间得出的，那里可获得紫外线测量和相关的气象参数。通过这些关系，可以将每日的紫外线剂量重建到1968年。测试表明，该模型即使在反照率较高的情况下，即使在一分钟的时间范围内也能正常工作。测量和计算的紫外线辐照度的比较表明，该模型解释了1968-2001年期间平均高于18°的太阳高程的97％的方差。追溯到1968年的重建表明，由于长期的臭氧减少，最大紫外线辐射（晴天）已经增加。乌云显示出取决于季节的长期变化，尤其是卷云的增加。因此，与单独的臭氧下降所预期的变化相比，紫外线剂量在某些月份中的增加量减少甚至减少。 5月至8月，总的云频率和云量有所减少。因此，平均紫外线剂量增加得远远超过仅凭臭氧层减少所能解释的。还表明，自1953年以来，卷云的光学厚度增加了。卷云发生频率较高的部分原因是更频繁的凝结尾迹。除此之外，观察到的对流层顶长期上升和冷却有利于卷云的形成。但是，尚未详细研究气候变化和水循环加剧是否是卷云趋势的原因。

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