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一种融合时空特性的气温缺失记录重建方法

1. 1. 河南大学黄河中下游数字地理技术教育部重点实验室, 河南 开封 475004
2.河南大学计算机与信息工程学院, 河南 开封 475004
3. 武汉大学测绘遥感信息工程国家重点实验室, 湖北 武汉 430079
• 收稿日期:2013-06-05 修回日期:2013-08-12 出版日期:2014-09-10 发布日期:2014-09-10
• 作者简介:

作者简介：陈锋锐（1982-）,男,河南禹州人,讲师,博士,主要从事多元地统计、多源信息融合研究。E-mail:fruich@gmail.com

• 基金资助:
中国博士后科学基金（2012M511571）、国家自然科学基金（41101434）项目资助

A Novel Imputation Method of Missing Air Temperature Records Based on Merging Spatio-temporal Characteristics

Feng-rui CHEN1(), Yu LIU2, Xi LI3

1. 1.Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions, Ministry of Education, Henan University, Kaifeng, Henan 475004, China
2. School of Computer and Information Engineering, Henan University, Kaifeng, Henan 475004, China
3. State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan, Hubei 430079, China
• Received:2013-06-05 Revised:2013-08-12 Online:2014-09-10 Published:2014-09-10

Abstract:

Data missing is frequently encountered in climate variables due to many reasons, such as instrument failures in the observatory, meteorological extremes, and observation recording errors. However, several types of climatic analysis require the availability of data not only covering a long enough period of time, but also forming a complete and homogeneous series. This paper presented a novel imputation method for missing air temperature records by merging their spatio-temporal characteristics. On the basis of extending Kriging model, a nonstationary Kriging method which assumes that the mean is known and varying in study area was proposed. Firstly, the trend of air temperature in each station was attained by analyzing its time series data, and linear interpolation was adopted in this study. Then, geostatistical analysis were performed on the errors between the trend and observed values. Finally, the spatio-temporal information of air temperature was integrated into the proposed Kriging model. Three other imputation methods, including linear interpolation, ordinary Kriging based on DEM (OKD) and normal ratio, were introduced to compare with. The results show that: 1) Besides OKD, the imputation accuracy of the other three methods varies obviously in 12 months. For linear interpolation, its imputation accuracy in May and July-October is much higher than that in the rest of the month. Normal ratio has higher imputation accuracy in April-November. The proposed method has higher imputation accuracy in March-October, with mean absolute error (MAE) less than 0.2℃. 2) Normal ratio has the largest MAE (4.17℃) in December and the least MAE (0.18℃) in October, this means that it has poor robustness. Compared with linear interpolation, the difference between the maximum and minimum MAE values of OKD is much less (0.25℃), thus it has better robustness. With the difference being 0.1℃ only, the proposed method has the strongest robustness. 3) Air temperature contains the temporal and spatial characteristics together. Linear interpolation only considers its temporal characteristics but ignores its spatial characteristics, while OKD only considers its spatial characteristic but ignores its temporal characteristics. Therefore, they don't attain the satisfactory imputation results. With partly taking the spatio-temporal characteristics of air temperature into account, normal ratio can attain higher imputation accuracy in March-November. However, this method has poor robustness. When air temperature in study area varies sharply or fluctuates around 0℃, normal ratio has lower imputation accuracy. As a result, its overall imputation accuracy is still lower. Among these methods, the proposed method has the smallest MAE and root mean square error in each month and produces the best imputation results.

• P456.8