地理学报 ›› 2017, Vol. 72 ›› Issue (7): 1207-1220.doi: 10.11821/dlxb201707007

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基于广义加性模型估算1979-2014年三峡库区降水及其特征分析

王圆圆(), 郭徵, 李贵才, 郭兆迪   

  1. 国家卫星气象中心,北京 100081
  • 收稿日期:2016-11-25 修回日期:2017-04-05 出版日期:2017-08-07 发布日期:2017-08-08
  • 作者简介:

    作者简介:王圆圆(1981-), 女, 安徽六安人, 博士, 副研究员, 主要从事生态环境遥感应用研究。E-mail: wangyuany@cma.gov.cn

  • 基金资助:
    国家公益气象行业专项(GYHY201406035), 国家自然科学基金项目(41301461);R&D Special Fund for Public Welfare Industry (Meteorology), No.GYHY201406035 National Natural Science Foundation of China, No.41301461

Precipitation estimation and analysis of the Three Gorges Dam region (1979-2014) by combining gauge measurements and MSWEP with generalized additive model

Yuanyaun WANG(), Zheng GUO, Guicai LI, Zhaodi GUO   

  1. National Satellite Meteorological Centre, Beijing 100081, China
  • Received:2016-11-25 Revised:2017-04-05 Online:2017-08-07 Published:2017-08-08

摘要:

高精度、长时间序列、空间连续的降水产品是气候分析、水文模拟等众多研究领域中的重要输入。近期欧洲研究人员融合了3种不同类型的降水数据:站点观测、遥感产品、再分析资料,制作了全球1979-2014年3小时一次0.25°空间分辨率的降水产品(Multi-Source Weighted-Ensemble Precipitation, MSWEP),凭借高时空分辨率及其对多源信息的挖掘和融合,该产品一经发布即受到广泛关注。本文利用三峡库区及附近地区气象站点的降水资料对MSWEP月降水数据进行评估,采用广义加性模型算法(General Additive Model,GAM)融合站点降水空间插值结果和MSWEP产品,对三峡库区融合后降水进行分析。主要结论为:① 降水估算精度呈现冬春季偏高、夏秋季偏低的特征,MSWEP产品与站点插值方法具有互补性,前者对夏秋季降水估算精度更高,后者对冬春季降水估算精度更高;② GAM算法可以充分发挥站点插值和MSWEP数据各自的优势,提高区域降水估算精度,与融合前相比,均方根误差减少了17%~50%,相关系数r提高了10%~30%;③ 2003年库区蓄水前后降水变化的主要特征有:库区中部长江以南地区汛期降水(5-10月)下降,库区西部干季(1-4月,11-12月)降水增加,库区外围西北部(大巴山地区)汛期降水增加,降水空间格局异质性增加,干季降水占全年降水比例升高。

关键词: 降水, 三峡库区, MSWEP, GAM

Abstract:

Long time-series, spatially-contiguous and accurate precipitation products are one of the most important inputs for various studies, including climate change detection, hydrological modelling, drought monitoring, etc. However, due to its high spatio-temporal variability, precipitation is one of the meteorological elements that are most difficult to estimate. Recently, a new global gridded precipitation dataset that merges gauge measurements, satellite products, and reanalysis data, has been produced. Owing to its high spatial resolution, long time span, and comprehensive combination of different precipitation data sources, MSWEP data have received wide attention since its release. In this study, we first evaluated accuracy of MSWEP monthly precipitation using local gauge measurements in the Three Gorges Dam region, then produced more accurate precipitation data by combining MSWEP and gauge measurements with the GAM (Generalized Additive Model) method, and finally analysed precipitation changes before and after the dam water level rose to 135 m in June 2003. Main conclusions are drawn as follows. (1) No matter what methods are used, estimation accuracy of precipitation shows strong seasonality: more accurate in cold-dry season (spring and winter), while less accurate in hot-wet season (summer and autumn). Gauge measurement and MSWEP are complementary, with the former being more accurate in cold-dry season and the latter being more accurate in hot-wet season. (2) GAM can take advantages of both gauge measurements and MSWEP with flexibility and achieve more accurate precipitation estimation (rmse decreases by 17%-50%, and r increases by 10%-30%). There are still great seasonal variations in accuracy, with rmse being 8-20 mm in spring and winter and 20-50 mm in summer and autumn. (3) Based on the precipitation estimation results obtained in step 2, we found the following phenomena after the water level rose to 135 m in 2003: 1) dam regions south of the Yangtze River show a precipitation reduction over May-October; 2) dam regions in the western part show a precipitation increase over November-April; 3) The northwestern part outside core dam regions shows a precipitation increase over May-October, which is consistent with the results of other studies; 4) precipitation shows an increase in spatial heterogeneity, but a slight decrease in seasonality conveyed by an increase in proportion of precipitation in dry season.

Key words: precipitation, Three Gorges Dam region, MSWEP, GAM