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Calculation and Validation Method of Cloud Amount by High Spatial Resolution Satellite Data
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摘要: 该文利用国家卫星气象中心1998—2008年NOAA卫星的存档数据，在再定标和精定位等数据再处理基础上，利用自行研发的云检测算法及云量计算方法，生成空间分辨率为0.01°×0.01°、时间尺度为10年的逐日云量数据，并利用ISCCP和地面观测数据对计算得到的云参数进行数据质量评估。评估结果显示：利用NOAA数据的抽样云检测结果与ISCCP-DX数据相比，晴空像元检测率具有0.70左右的一致性；有云像元检测率具有60%左右的一致性。卫星计算的总云量与地面观测总云量间的月平均相关系数大于0.70。Abstract: Cloud plays an important role in earth-atmosphere radiation balance system, atmospheric circulation and climate change. Surface observation is a regular method to obtain cloud amount data but it is limited by time and place. International Satellite Cloud Climatology Project (ISCCP) offers cloud parameters product with better quality, but the best spatial resolution is just 30 km. Based on re-calibration and accurate re-location to NOAA daily data during 1998—2008, total cloud amount are calculated with improved cloud detection and radiation calculation method, and validated by ISCCP and surface regular observation data. The temporal and spatial resolution (daily and 0.01°×0.01°) of this cloud amount data is much better than ISCCP product. The sub cloud pixel covered problem is also resolved. Compared with ISCCP DX cloud detection data, validation result shows that clear pixel detection consistence reaches 0.70, cloud pixel detection consistence reaches 0.60, and total cloud detection consistence reaches 0.57. For cloud amount, the coefficient between the calculated cloud amount and surface observation is higher than 0.70. The main differences between cloud amount of ISCCP and calculated data come from two aspects. First, ISCCP method doesn't consider sub-pixel problem reasonably. If one pixel is covered by cloud, ISCCP method regards its cloud amount as one while with the radiation calculation method, clear and completely cloudy cover radiation is calculated, and then every pixel cloud amount according to its radiation value is calculated. Second, different spatial resolution and targets influence the evaluation of the two sets of data. Limited by observation angles and time, ground and satellite observations are not the same. The validation shows that the calculated long time series cloud parameters with high temporal and spatial resolution have good quality, and could play important role in weather analysis and climate change research.
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Key words:
- satellite data;
- cloud amount;
- high spatial resolution;
- long time series
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图 1 自行计算的1998年卫星云检测一致率 (a)、有云像元检测一致率 (b)、晴空像元检测一致率 (c) 和有云像元检测评分 (d) 的时间分布
Fig. 1 The temperal distribution of calculated cloud detection accuracy (a), cloud detection hit rate (b), clear detection hit rate (c), Threat Score (d) in 1998
图 2 自行计算的2007年卫星云检测一致率 (a)、有云像元检测一致率 (b)、晴空像元检测一致率 (c) 和有云像元检测评分 (d) 的时间分布
Fig. 2 The temporal distribution of calculated cloud detection accuracy (a), cloud detection hit rate (b), clear detection hit rate (c) and Threat Score (d) in 2007
图 3 自行计算的1998年卫星云检测结果与ISCCP DX云检测对比评估指标分析
Fig. 3 Evaluation parameters for calculated cloud detection and ISCCP DX data in 1998
图 4 自行计算的2007年卫星云检测结果与ISCCP DX云检测对比评估指标分析
Fig. 4 Evaluation parameters for calculated cloud detection and ISCCP DX data in 2007
图 5 NOAA反演的总云量与地面观测总云量间的CCA相关系数随时间变化
Fig. 5 The temporal distrubution of CCA relation coefficients of retrieval cloud amount and ground observation
图 6 2007年7月12日可见光云图 (a)、地面观测总云量 (b) 与利用NOAA/卫星数据计算总云量 (c) 的对比
Fig. 6 Comparison of visible image (a), ground observation (b) and retrieval cloud amount of NOAA (c) on 12 July 2007
图 7 完全晴空 (a)、完全云盖 (b) 亮温变化引起的估计云量变化
Fig. 7 The relationship of the brightness temperature bias about clear (a) and cloudy (b) to retrieval cloud amount
表 1 NOAA数据与ISCCP数据云检测联立表
Table 1 Contingency table for NOAA and ISCCP cloud detection
NOAA云像元 NOAA晴空像元 ISCCP云像元 A B ISCCP晴空像元 C D 
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表 2 地面观测与卫星计算总云量全国范围内逐日平均总云量的偏差分析
Table 2 Difference analysis between retrieval cloud amount and ground observation
月份 有效数据天数/d 平均偏差值/% 偏差的标准方差 1 31 4.46 0.06 2 28 3.64 0.04 3 28 6.91 0.04 4 30 5.54 0.04 5 27 7.47 0.05 6 30 15.13 0.03 7 31 16.03 0.02 8 31 14.92 0.03 9 30 11.13 0.05 10 29 7.17 0.06 11 29 0.80 0.03 12 31 3.33 0.06
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[1] Rossow W B, Walker A W, Beuschel D E, et al. International Satellite Cloud Climatology Project (ISCCP) Documentation of New Cloud Datasets. World Meteorological Organization, WMO/TD-No.737, 1996:1-115.s [2] Rossow W B, Walker A W, Gander L C. Comparison of ISCCP and other cloud amounts. J Climate, 1993, 6:2394-2418. doi: 10.1175/1520-0442(1993)006<2394:COIAOC>2.0.CO;2 [3] 魏丽, 钟强, 侯萍.中国大陆卫星反演云参数的评估.高原气象, 1996, 15(2):147-156. http://www.cnki.com.cn/Article/CJFDTOTAL-GYQX602.002.htm [4] 翁笃鸣, 韩爱梅.中国卫星总云量与地面总云量分布的对比分析.应用气象学报, 1998, 9(1):32-37. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=19980105&flag=1 [5] 刘洪利, 朱文琴, 宜树华, 等.中国地区云的气候特征分析.气象学报, 2003, 61(4):466-473. doi: 10.11676/qxxb2003.045 [6] 王旻燕, 王伯民. ISCCP产品和我国地面观测总云量差异.应用气象学报, 2009, 20(4):411-418. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20090404&flag=1 [7] 刘瑞霞, 陈洪滨, 郑照军, 等.总云量产品在中国区域的分析检验.应用气象学报, 2009, 20(5):571-578. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20090508&flag=1 [8] 丁守国, 石广玉, 赵春生.利用ISCCP D2资料分析近20年全球不同云类云量的变化及其对气候可能的影响.科学通报, 2004, 49(11):1105-1111. doi: 10.3321/j.issn:0023-074X.2004.11.016 [9] Rossow W B, Schiffer R A. Advances in understanding clouds from ISCCP. Bull Amer Meteor Soc, 1999, 80(11):2261-2287. doi: 10.1175/1520-0477(1999)080<2261:AIUCFI>2.0.CO;2 [10] Alan V D V, William J E, Senior Member. An automated dynamic threshold cloud masking algorithm for daytime AVHRR images over land. IEEE Transactions on Geoscience and Remote Sensing, 2002, 40(8):1682-1694. doi: 10.1109/TGRS.2002.802455 [11] Saunders R W, Kriebel K T. An improved method of detecting clear sky and cloudy radiances from AVHRR data. Int J Remote Sens, 1988, 9:123-150. doi: 10.1080/01431168808954841 [12] Peak J E, Tag P M. Segmentation of satellite imagery using hierarchical thresholding and neural networks. J Appl Meteor, 1994, 33: 605-616. doi: 10.1175/1520-0450(1994)033<0605:SOSIUH>2.0.CO;2 [13] Nowcasting and Very Short Range Forecasting SAF, Prototype Scientific Description for Météo France/CMS.SAF/NWC/MFCMS/MTR/PSD, Issue 1, Rev. 1, 2000. [14] 刘健.中国区域云特性分析及其在FY-2云检测中的应用.应用气象学报, 2009, 20(6):673-681. http://qikan.camscma.cn/jams/ch/reader/view_abstract.aspx?file_no=20090604&flag=1 [15] Coakley J A Jr, Bretherton Francis P. Cloud cover from high-resolution scanner data detecting and allowing for partially filled fields of view. J Geophys Res, 1982, 87: 4917-4932. doi: 10.1029/JC087iC07p04917 -
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