| 全天空图像分析西藏羊八井2009～2010年云量特征 |
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| 引用本文： | 霍娟,吕达仁.全天空图像分析西藏羊八井2009～2010年云量特征[J].气候与环境研究,2012,17(4):393-399. |
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| 作者姓名： | 霍娟 吕达仁 |
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| 作者单位： | 中国科学院大气物理研究所中层大气和全球环境探测开发重点实验室,北京,100029 |
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| 基金项目： | 国家自然科学基金国际合作重大项目40710059003;公益性行业(气象)科研专项GYHY200806031 |
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| 摘 要： | 运用西藏羊八井观测站2009～2010年近1年的高时空分辨率全天空图像资料分析了测站上空的日间云量特征。年平均总云量统计结果为5.2;冬夏季节云量分布差别明显,夏季平均云量大,冬季小;无云、少云天气多出现在冬季上午,而夏季午后满云情况较多;1～4月及11、12月(冬半年)云量日变化特征明显,上午逐步增加,至17:00(北京时间)左右到达高值,随后逐步下降,形成白天云量渐多夜间云量消散的"循环"过程。运用该地资料还分析了运用时间概率方法估算的点云量与实际云量的差异,小时平均结果显示无云及满云天气条件下二者云量一致性较高,而对中等云量天气二者相差较大。更长时间尺度(天平均)的统计对比表明,随着统计样本增加二者差距缩小。总体来看少云天气情况下点概率云量估算低于实际天空云量,当天空多云时点概率云量则大于实际天空云量。
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| 关 键 词： | 青藏高原 云量 气候变化 全天空图像 |
| 收稿时间： | 2010/11/16 0:00:00 |
| 修稿时间： | 2012/4/27 0:00:00 |
Cloud Amount Analysis at Yangbajing of Tibet in 2009-2010 Using All-Sky Images |
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| HUO Juan
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L Daren.Cloud Amount Analysis at Yangbajing of Tibet in 2009-2010 Using All-Sky Images[J].Climatic and Environmental Research,2012,17(4):393-399. |
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| Authors: | HUO Juan L Daren |
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| Institution: | Key Laboratory for Atmosphere and Global Environment Observation, Institute of Atmospheric Physics, Beijing 100029;Key Laboratory for Atmosphere and Global Environment Observation, Institute of Atmospheric Physics, Beijing 100029 |
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| Abstract: | At Yangbajing observatory,Tibet,an all-sky imager has been in operation for more than one year since April 2009,to measure and record cloud amounts and types.The daily cloud amount statistics over Yangbajing based on the high temporal and spatial resolution dataset is reported.The annual mean cloud amount is 5.2.The cloud-amount distributions show strong summer/winter contrasts.The mean cloud-amount is higher in summer than in winter.Lowest cloud frequencies are founded in the morning of winter and the highest cloud frequencies are founded in the afternoon of summer.Cloud amount distributions also show an obvious diurnal variation characteristic during the "winter" half-year(November,December,and January to April) that cloud amounts increase gradually from morning and reaches a peak in the late afternoon,afterward drops gradually.At later,another cloud amount estimation method(described as "temporal cloud amount") that calculating the occurring frequency of cloud at a fixed direction during a period is compared with the true cloud amount.For clear and overcast conditions,both of them agree much better to each other,but they show great discrepancy for broken-cloudiness.Averaged over a longer time period,such as one day,the bias becomes lower.For heavy-cloudiness conditions,true cloud amount is higher than temporal cloud amount,but it is often lower in light-cloudiness conditions. |
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| Keywords: | Tibetan Plateau cloud amount climate change all-sky image |
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