| 北京等7个气象台站太阳总辐射观测资料的准确度评估 |
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| 引用本文： | 邱金桓,许潇锋,杨景梅.北京等7个气象台站太阳总辐射观测资料的准确度评估[J].应用气象学报,2008,19(3):287-296. |
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| 作者姓名： | 邱金桓 许潇锋 杨景梅 |
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| 作者单位： | 中国科学院大气物理研究所中层大气与全球环境观测实验室, 北京 100029 |
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| 基金项目： | 国家重点基础研究发展计划(973计划)
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国家自然科学基金 |
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| 摘 要： | 基于地面太阳短波总辐射对气溶胶光学特性和地表反照率的敏感性, 该文提出了一个评估我国气象台站总辐射资料准确度的方法。该方法选用气溶胶光学厚度和太阳天顶角较小情形下的晴天辐射资料, 从太阳直射辐射反演气溶胶光学厚度, 用于计算宽带透过率, 再从该透过率和总辐射资料反演太阳常数E0, P, 并采用E0, P对世界辐射基准 (WRR) 的偏差表示总辐射资料的不确定性。模拟结果表明:气溶胶折射率虚部和大气柱水汽含量的输入误差是两个主要的评估不确定因子。用于准确度评估的资料越多, 越有利于平滑气溶胶、水汽含量等输入参数随机误差的效应, 评估结果越合理。应用这一方法, 该文评估了2000— 2004年我国沈阳、额济纳旗、北京、乌鲁木齐、格尔木、上海和广州7个气象台站总辐射资料的准确度。7个站共有1161个太阳常数反演值, 都满足太阳天顶角余弦 (μ0) 大于0.7的条件。这些E0, P值对WRR的最大偏差为7.33%, 97.78%的E0, P值对WRR的偏差小于5%, 总平均E0, P值对WRR偏差只有-1.15 %。依据这些结果, 当μ0≥0.7时, 这些台站的晴天总辐射资料的不确定度估计为5%。
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| 关 键 词： | 总辐射 准确度评估 透过率 |
| 收稿时间： | 2007-03-21 |
An Accuracy Estimation of Global Solar Radiation Measurements at Meteorological Observatories in China |
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| Qiu Jinhuan,Xu Xiaofeng,Yang Jingmei.An Accuracy Estimation of Global Solar Radiation Measurements at Meteorological Observatories in China[J].Quarterly Journal of Applied Meteorology,2008,19(3):287-296. |
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| Authors: | Qiu Jinhuan Xu Xiaofeng Yang Jingmei |
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| Institution: | Laboratory for Middle Atmospheric and Global Enviroment Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 |
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| Abstract: | When routine observations are performed by the pyranometer in the outside field, measurement errors will be caused by some factors, such as the polluted camera lens by which the measured value will be made less than the reality, as well as the temperature error, the cosine errorand the tilt error etc. Reliable accuracy estimation of the pyranometer-received global solar radiation (GSR) is significant to improve the use of the measurements. In the case of thin aerosol optical thickness (AOT) and small solar zenith angle, three characteristics of pyrheliometer-received GSR are presented. Compared with the diffuse solar radiation, the direct solar radiation contributes dominatingly to GSR; owing to the opposite shifts of direct and diffuse solar radiation with increasing AOT (the former decreases while the latter increases), GSR shows a weak sensitivity to AOT, molecular optical thickness, aerosol size distribution and refractive index; there is a small hemispherical reflectance and hence a weak sensitivity of GSR to the surface albedo. According to these properties, a method for accuracy estimation of GSR measurements at Chinese meteorological observatories is proposed. In the condition of cloud-free, thin AOT and small solar zenith angle, the solar constant (marked as E0, P) is retrieved from the GSR measurements and the broadband transmittance which is calculated using AOT retrieved from direct solar radiation. The deviation of the E0, P to the GRR (global radiation reference) is treated as an indicator of the uncertainty of GSR data. The simulations show that the uncertainties of the imaginary part of aerosol refractive index and the water vapor content are the two main error factors. Effects of random errors in input parameters such as aerosol optical properties, water vapor content and so on can be weakened by more statistical examples for the estimation, then more reasonable estimation results are produced. This method is applied to evaluating accuracies of GSR data at seven observatories which are Shenyang, Ejin Qi, Beijing, Urumqi, Golmud, Shanghai and Guangzhou in China. There are totally 1161 E0, P retrievals from GSR data in these seven observatories during 2000—2004, which are all measured in such conditions as clear (cloud-free) days; the solar zenith angle cosine (μ0) being larger than 0.7; τa(750 nm AOT) /μ0 < 0.3; the atmospheric column water vapor content being less than 2.0 cm. Among all these E0, P retrievals, the maximum deviation to GRR is 7.33 %, deviations of 97.78 %, E0, P retrievals are less than 5%, and the standard deviation is within 4.05% for every observatory. It is estimated that the uncertainty of GSR data in these observatories is usually better than 5% in the clear days and for μ0≥0.7. |
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| Keywords: | global solar radiation accuracy estimation transmittance |
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