Journal of Geo-information Science >
Spatial Downscaling of TRMM Precipitation Data Based on GWR Model in Northeast China
Received date: 2014-09-04
Request revised date: 2015-06-15
Online published: 2015-09-07
Copyright
The availability of precipitation data with high spatial resolution is critical for several applications, such as hydrology, meteorology and ecology. The Tropical Rainfall Measuring Mission (TRMM) data sets can provide effective precipitation information, but at a coarse resolution (0.25°). Therefore, it is very necessary to improve its resolution. The existing TRMM-downscaling methods tend to use ordinary linear regression (OLS), which is known as a global model. However, it ignores the local characteristics. In this paper, the relationship between TRMM and Normalized Difference Vegetation Index (NDVI) was explored by using a local regression analysis approach that is known as geographically weighted regression (GWR). The relationship was used to construct the precipitation downscaling model, which then produces 1 km downscaled precipitation data. The OLS model and GWR model were tested for the data of Northeast China from 2000 to 2010. The accuracy of the downscaled data was validated by the observed precipitation data from 93 meteorological stations located in the study area. Some conclusions can be drawn from our study: (1) there is a strong correlation between TRMM data and the observation data obtained from meteorological stations (R = 0.9172). Overall, the TRMM precipitation is higher than the observed data at all stations. (2) Two downscaling methods were applied in this study, and the results show that the downscaled precipitation based on GWR model produces better results. It produces better R values and the reduced RMSE. Thus, the GWR model is more suitable for the spatial downscaling of TRMM. (3) The correlation coefficient between the downscaled precipitation based on GWR model and the observed data is ranging between 0.44 and 0.97, and its spatial distribution is disperse. (4) The downscaled precipitation data improves the spatial resolution (from 0.25° to 1 km), which can better reflect the characteristics of the precipitation in the study area. It could provide more accurate and realistic precipitation data for the studies at small scales.
Key words: TRMM precipitation; spatial downscaling; GWR; Northeast China
LIU Xiaochan , ZHANG Hongyan , ZHAO Jianjun , GUO Xiaoyi , ZHANG Zhengxiang , PIAO Meihua . Spatial Downscaling of TRMM Precipitation Data Based on GWR Model in Northeast China[J]. Journal of Geo-information Science, 2015 , 17(9) : 1054 -1062 . DOI: 10.3724/SP.J.1047.2015.01055
Fig. 1 Study area and rain gauge stations图1 研究区位置及气象站点分布 |
Fig. 2 Precipitation scatter diagram between TRMM and rain gauges in Northeast China during 2000-2010图2 2000-2010年东北地区TRMM降水数据与实测降水数据散点图 |
Fig. 3 Radar chart of the correlation coefficient R图3 相关系数R雷达图 |
Fig. 4 TRMM precipitation data, the predictive precipitation, the residual data and the downscaling results图4 TRMM降水数据、模型预测降水、残差数据及降尺度结果 |
Tab. 1 Validation results of downsacling precipitation表1 降尺度结果验证 |
评价指标 | TRMM | OLS降尺度 | GWR降尺度 |
---|---|---|---|
R | 0.9595 | 0.9049 | 0.9412 |
BIAS | 0.1240 | 0.0455 | 0.0904 |
RMSE | 85.514 | 83.431 | 80.283 |
Fig. 5 Scatter diagram of the annual mean TRMM, the downscaling precipitation based on OLS and the downscaling precipitation based on GWR versus meteorological station data图5 多年平均TRMM数据、OLS降尺度数据、GWR降尺度数据与观测数据的散点图 |
Fig. 6 Downscaling precipitation based on GWR model and OLS model with resolution of 1 km in 2001 and 2010图6 2001年和2010年GWR模型与OLS模型的降尺度结果 |
Tab. 2 Validation results of downsacling precipitation表2 降尺度结果验证 |
年份 | 评价指标 | TRMM | OLS降尺度 | GWR降尺度 |
---|---|---|---|---|
2001 | R | 0.9428 | 0.8887 | 0.9187 |
BIAS | 0.1245 | 0.1048 | 0.1038 | |
RMSE | 86.271 | 80.495 | 81.152 | |
2010 | R | 0.9422 | 0.9084 | 0.9400 |
BIAS | 0.0978 | 0.1004 | 0.0681 | |
RMSE | 131.827 | 140.287 | 125.209 |
3.3.4 降尺度数据相关系数空间分布 |
Fig. 7 Spatial distribution of R between downscaling precipitation based on GWR model and the observed data图7 东北地区的GWR模型降尺度结果与观测数据的相关系数空间分布 |
The authors have declared that no competing interests exist.
[1] |
|
[2] |
|
[3] |
|
[4] |
|
[5] |
|
[6] |
|
[7] |
|
[8] |
|
[9] |
|
[10] |
|
[11] |
|
[12] |
|
[13] |
|
[14] |
|
[15] |
|
[16] |
|
[17] |
|
[18] |
|
[19] |
|
[20] |
|
[21] |
|
[22] |
|
[23] |
|
[24] |
|
[25] |
|
[26] |
|
[27] |
|
[28] |
|
[29] |
|
[30] |
|
[31] |
|
[32] |
|
[33] |
|
/
〈 |
|
〉 |