The Lancang river basin is a typical area of lacking data with complicated terrain and climate characteristics. It is located in the upper reaches of Mekong river basin. There is great potential to carry out hydrological prediction in ungauged basins by using satellite estimate precipitation data. As a precipitation radar satellite, TRMM has been collecting plentiful fine temporal-spatial precipitation data, so it is significant to use the TRMM precipitation data to study hydrological and climatic characteristics in the Lancang river basin. However, it is necessary to check the accuracy of TRMM data before using it. Based on the correlation coefficients and scatter points slope methods, the accuracy of TRMM 3B43 data at monthly time scale during 1998-2009 was validated by using the 35 rain gauges data, which were distributed in the Lancang river basin and its surrounding areas. Then the influence of slope and elevation on the checking result based on Thiessen polygons and K-Means cluster methods was analyzed. Finally, principal component analysis was used to compare the differences of elevation and slope on the accuracy of TRMM 3B43. The results are obtained as follows. (1) Compared with the 35 rain gauges, TRMM 3B43 data displayed good accuracy in the whole study area at monthly time scale. (2) There were significant differences of accuracy among the 35 sites; the TRMM 3B43 data had good accuracy in the upstream and downstream of the research areas, while the middle area was poor, especially Bomi, Gongshan, Deqin and Shangrila. (3) Compared with slope, the influence of elevation on the accuracy of TRMM 3B43 was more complicated, and the accuracy showed that there was a high-low-high variation when the elevation decreased from upstream to downstream, which may be caused by strong spatial heterogeneity of precipitation in this area. (4) The slope of research area had great influence on the accuracy of TRMM 3B43 data, which decreased as the increase of slope, the middle research area has the maximum slope so the accuracy was the worst, while the upstream and downstream had relatively high accuracy due to flat terrain.
[1] Zhu Huiyi, Jia Shaofeng. Uncertainty in the spatial interpolation of rainfall data. Progress in Geography, 2004, 23(2):34-42. [朱会义, 贾绍凤. 降雨信息空间插值的不确定性分析. 地理科学进展, 2004, 23(2): 34-42.]
[2] Xia Jun, Tan Ge. Hydrological science towards global change: Progress and challenge. Resources Science, 2002, 24(3):1-7. [夏军, 谈戈. 全球变化与水文科学新的进展与挑战. 资源科学, 2002, 24(3): 1-7.]
[3] Robert F A, George J H, Alfred C. The Version-2 Global Precipitation Climatology Project (GPCP) monthly precipitationanalysis (1979-present). Journal of Hydrometeorology, 2003, 4(6):1147-1167.
[4] Xia Jun, Tan Ge, Li Xin. Hydrological prediction in ungauged basins. Journal of Glaciology and Geocryology, 2004, 26(2):192-196. [谈戈, 夏军, 李新. 无资料地区水文预报研究的方法与出路. 冰川冻土, 2004, 26(2): 192-196.]
[5] Su F F, Yang H, Dennis P L. Evaluation of TRMM Multisatellite Precipitation Analysis (TMPA) and its utility in hydrologicprediction in the La Plata Basin. Journal of Hydrometeorology, 2007, 9: 622-640.
[6] Sivapalan M, Takeuchi K, Franks S W. IAHS decade on predictions in ungauged basins (PUB), 2003-2012: Shaping anexciting future for the hydrological sciences. Hydrological Sciences Journal, 2003, 48(6): 857-880.
[7] Kummerow C, Barnes W. The Tropical Ra
[8] Hirose, Masafumi, Nakamura K J. Spatial and seasonal variation of rain profiles over Asia observed by spaceborneprecipitation radar. Journal of Climate, 2002, 15: 3443-3458.
[9] Hirose Masafumi, Nakamura K J. Spatiotemporal variation of the vertical gradient of rainfall rate observed by the TRMMprecipitation radar. Journal of Climate, 2004, 17: 3378-3397.
[10] George J H, Robert F A, David T B. The TRMM Multisatellite Precipitation Analysis (TMPA): Quasi-global, multiyear,combined-sensor precipitation estimates at fine scales. Journal of Hydrometeorology, 2006, 8(1): 38-55.
[11] Scott C, Thomas W C, Scott A L. A comparison of TRMM to other basin-scale estimates of rainfall during the 1999Hurricane Floyd flood. Natural Hazards, 2007, 43(2): 187-198.
[12] Bai Aijuan, Liu Changhai, Liu Xiaodong. Diurnal variation of summer rainfall over the Tibetan Plateau and itsneighboring regions revealed by TRMM multi-satellite precipitation analysis. Chinese Journal of Geophysics, 2008, 51(3): 704-714. [白爱娟, 刘长海, 刘晓东. TRMM多卫星降水分析资料揭示的青藏高原及其周边地区夏季降水日变化.地球物理学报, 2008, 51(3): 704-714.]
[13] Bai Aijuan, Fang Jiangang, Zhang Kexiang. Summer rainfall in shaanxi and its neighborhood regions observed by TRMMsatellite. Journal of Catastrophology, 2008, 23(2): 41-45. [白爱娟, 方建刚, 张科翔. TRMM卫星资料对陕西及周边地区夏季降水的探测. 灾害学, 2008, 23(2): 41-45.]
[14] Liu Junfeng, Chen Rensheng, Han Chuntan. Evaluating TRMM multi-satellite precipitation analysis using gaugeprecipitation and MODIS snow-cover products. Advances in Water Science, 2010, 21(3): 343-348. [刘俊峰, 陈仁升, 韩春坛. 多卫星遥感降水数据精度评价. 水科学进展, 2010, 21(3): 343-348.]
[15] Li Jinggang, Li Jiren, Huang Shifeng. Characteristics of the recent 10 year flood/drought over the Dongting Lake Basinbased on TRMM precipitation data and regional integrated Z-index. Resources Science, 2010, 32(6): 1103-1110. [李景刚,李纪人,黄诗峰. 基于TRMM数据和区域综合Z 指数的洞庭湖流域近10 年旱涝特征分析. 资源科学, 2010, 32(6):1103-1110.]
[16] Chen Ju, Shi Ping, Wang Dongxiao. Spatial distribution and seasonal variability of the rainfall observed from TRMMprecipitation radar (PR) in the South China Sea Area (SCSA). Advance in Earth Sciences, 2005, 20(1): 29-35. [陈举, 施平, 王东晓. TRMM卫星降雨雷达观测的南海降雨空间结构和季节变化. 地球科学进展, 2005, 20(1): 29-35.]
[17] Islam M N, Uyeda H. Use of TRMM in determining the climatic characteristics of rainfall over Bangladesh. RemoteSensing of Environment, 2007, 108(3): 264-276.
[18] Xie P P, Arkin P A. Global precipitation: A 17-year monthly analysis based on gauge observations, satellite estimates, andnumerical model outputs. Bulletin of the American Meteorological Society, 1997, 78(11): 2539-2558.
[19] Mark N, Martin T, Mike H. Precipitation measurements and trends in the twentieth century. International Journal ofClimatology, 2001, 21(15): 1889-1922.
[20] Yu Zhongbo. Principles and Applications of Distributed Watershed Hydrology. Beijing: Science Press, 2008: 33-34. [余钟波.流域分布式水文学原理与应用. 北京: 科学出版社, 2008: 33-34.]
[21] Gong Jianya. Geographical Information System. Beijing: Science Press, 2001: 187. [龚健雅. 地理信息系统基础. 北京:科学出版社, 2001: 187.]
[22] Li Lijuan, Li Haibing, Wang Juan. Analysis on hydrological and water quality character and their spatial and temporaldistribution in Lancangjiang River. Scientia Geographica Sinica, 2002, 22(1): 49-56. [李丽娟, 李海滨, 王娟. 澜沧江水文与水环境特征及其时空分异. 地理科学, 2002, 22(1): 49-56.]
[23] Li Zhenghai, Song Guobao, Gao Jixi. Study on the relationship among land use tempo-spatial change, range-gorgedistribution and channels effect in longitudinal range-gorge region. Chinese Science Bulletin, 2006, 51(suppl.2):90-99. [李政海, 宋国宝, 高吉喜. 纵向岭谷区土地利用时空变化与岭谷格局及通道效应的关系研究. 科学通报, 2006,51(增刊2): 90-99.]
[24] Qin Jian. Weather and Climate in Low Latitude Plateau. Beijing: China Meteorological Press, 1997: 1-2. [秦剑. 低纬高原天气气候. 北京: 气象出版社, 1997: 1-2.]
[25] Ming Qingzhong. The analysis to the landforms character of the river valley in the Three Parallel Rivers Region. Journalof Yunnan Normal University: Natural Sciences Edition, 2007, 27(2): 65-69. [明庆忠. 纵向岭谷三江并流区河谷地貌特征分析. 云南师范大学学报: 自然科学版, 2007, 27(2): 65-69.]
[26] Wu Liqun, Li Xuehui. Analysis on change of annual precipitation altitude in high mountain areas. Yunnan GeographicEnvironment Research, 2004, 16(2): 4-7. [伍立群, 李学辉. 高山地区年降水量随高程变化分析. 云南地理环境研究,2004, 16(2): 4-7.]
[27] You Weihong, Wu Xiangyun, Li Dejun. Temporal-spatial features and law of summer precipitation interannual variabilityover the Longitudinal Range-Gorge Region under effect of the summer monsoon. Progress in Geography, 2007, 26(5):23-31. [尤卫红, 吴湘云,李德俊. 夏季风作用下的纵向岭谷区夏季降水量年际变化的时空特征和规律. 地理科学进展, 2007, 26(5): 23-31.]infall Measuring Mission (TRMM) Sensor Package. Journal of Atmospheric andOceanic Technology, 1998, 15: 809-817.