四种网格化降水产品估算中国大陆区域降雨侵蚀力比较

Comparison of the four gridded precipitation products for estimating regional rainfall erosivity in China's Mainland

降雨侵蚀力反映了降雨对土壤侵蚀的潜在能力,准确评估降雨侵蚀力对水土保持规划和水土流失治理具有重要意义。近年来,网格化降水产品在计算中国的降雨侵蚀力方面发挥了积极作用,但不同降水产品存在一定的区域差异性。因此,为评估各类降水产品在不同区域的适应性以利于降雨侵蚀力的准确估计,该研究选用了4种网格化降水产品:中国逐日网格降水量实时分析系统数据集(China gauge-based daily precipitation analysis,CGDPA)、中国区域地面气象要素数据集(China meteorological forcing dataset,CMFD)、中国地面降水日值0.5°×0.5°格点数据集(v2.0)(Dataset of gridded daily precipitation in China(Version2.0),CN0.5)、热带降水测量计划-多卫星降水分析测量产品(tropical rainfall measurement mission-multisatellite precipitation analysis,TRMM-TMPA)3B42V7,采用日降雨侵蚀力模型计算各产品在2008-2013年中国大陆地区的降雨侵蚀力,并以中国大陆地区的738个气象站点的降水数据估算的降雨侵蚀力为参照,对比分析4种降水产品估算的月、季、年3个时间尺度下降水侵蚀力在中国大陆地区及其9个农业分区的空间分布情况、年际年内变化趋势,最后利用贝叶斯加权平均法分析各产品在不同区域的效用。结果表明:1)在空间分布上,4种降水产品计算的降雨侵蚀力及其变化率与相应地面测站数据计算的结果一致,降水侵蚀力均呈自西北向东南递增的空间分布特征;2)在不同时间尺度下,4种降水产品与实测降水数据的时间变化趋势一致,除CGDPA在青藏高原区高估了降雨侵蚀力,4种降水产品在不同分区均低估了降雨侵蚀力;3)在不同时间尺度下,推荐使用CMFD估算青藏高原区降雨侵蚀力,其他分区推荐使用CGDPA;总体而言,CGDPA、CMFD相对于CN0.5与TRMM整体上都有较好的适用性。研究可为降雨侵蚀力的计算及其他领域选用网格化降水产品提供参考。

Soil erosion has been one of the major environmental factors to restrict the economy and social development.Rainfall erosivity can be used to represent the potential capacity of rainfall for soil erosion.It is a high demand to accurately assess the rainfall erosion force for the decision-making on soil and water conservation.Among them,the gridded precipitation products can be expected to calculate rainfall erosivity.But there is great regional variability in the different precipitation products.Therefore,this study aims to assess the adaptability of the various types of precipitation products in different regions,in order to realize the accurate estimation of rainfall erosivity.The daily precipitation data was collected from 738 meteorological stations and four sets of high-resolution gridded precipitation products(China gauge-based daily precipitation analysis,CGDPA;China meteorological forcing dataset,CMFD;Dataset of gridded daily precipitation in China(Version 2.0),CN0.5;tropical rainfall measurement mission-multi satellite precipitation analysis,TRMM-TMPA),from 2008 to 2013 in China's Mainland.The daily precipitation erosion force model was used to calculate the rainfall erosivity,and then to compare it with the standard data from the meteorological stations.The annual rainfall erosion distribution of precipitation products and measured data were compared to determine the multi-year trends of rainfall erosion of precipitation products and measured data by one-dimensional linear regression.Finally,the Bayesian model averaging(BMA)was used to calculate the weights of different precipitation products in the nine agricultural regions and different time scales.The results show that:1)In terms of spatial distribution,the rainfall erosivity calculated by the four precipitation products and change rates were consistent with the ground station data.All rainfall erosivity showed an increasing pattern from the northwest to the southeast.Specifically,the CN0.5 was underestimated in the Loess Plateau,Huang-huai-hai Plain,Sichuan Basin and surrounding areas,the middle and lower reaches of the Yangtze River,Yunnan-Guizhou Plateau,and Southern China.CGDPA was overestimated in the Tibetan Plateau region near the Himalayas.2)At different time scales,there was the consistency in the temporal trends of the four precipitation products and the measured precipitation.On the monthly scale,there was a low region-wide average rainfall erosion force between December and January,whereas,the peak values all occurred from June to August.On the seasonal scale,the low values of the global average rainfall erosion occurred in winter,whereas,the peak values occurred in summer.On the annual scale,the highest values of the global average rainfall erosion occurred in 2010,while the lowest was in 2011.Four precipitation products underestimated the rainfall erosivity.3)The statistical indicators of CGDPA and CMFD were better than those of TRMM and CN0.5 at different time scales.CGDPA presented the highest Bayesian weight,rather than the Qinghai-Tibet Plateau region as the highest weight of the rainfall erosion force in CMFD.In general,the CGDPA and CMFD performed overall better applicability,compared with CN0.5 and TRMM.The gridded precipitation products can be expected to estimate the rainfall erosion calculation in China's Mainland.The finding can provide a strong reference to selecting the precipitation products for the rainfall erosion calculation in various agricultural sub-regions,particularly for regional soil and water conservation and agricultural management.