Accounting for spatiotemporal errors of gauges: A critical step to evaluate gridded precipitation products
AffiliationUniv Arizona, Dept Hydrol & Atmospher Sci
MetadataShow full item record
PublisherELSEVIER SCIENCE BV
CitationTang, G., Behrangi, A., Long, D., Li, C., & Hong, Y. (2018). Accounting for spatiotemporal errors of gauges: A critical step to evaluate gridded precipitation products. Journal of Hydrology, 559, 294-306. https://doi.org/10.1016/j.jhydrol.2018.02.057
JournalJOURNAL OF HYDROLOGY
Rights© 2018 Elsevier B.V. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at email@example.com.
AbstractRain gauge observations are commonly used to evaluate the quality of satellite precipitation products. However, the inherent difference between point-scale gauge measurements and areal satellite precipitation, i.e. a point of space in time accumulation v.s. a snapshot of time in space aggregation, has an important effect on the accuracy and precision of qualitative and quantitative evaluation results. This study aims to quantify the uncertainty caused by various combinations of spatiotemporal scales (0.1 degrees-0.8 degrees and 1-24 h) of gauge network designs in the densely gauged and relatively flat Ganjiang River basin, South China, in order to evaluate the state-of-the-art satellite precipitation, the Integrated Multi satellite Retrievals for Global Precipitation Measurement (IMERG). For comparison with the dense gauge network serving as "ground truth", 500 sparse gauge networks are generated through random combinations of gauge numbers at each set of spatiotemporal scales. Results show that all sparse gauge networks persistently underestimate the performance of IMERG according to most metrics. However, the probability of detection is overestimated because hit and miss events are more likely fewer than the reference numbers derived from dense gauge networks. A nonlinear error function of spatiotemporal scales and the number of gauges in each grid pixel is developed to estimate the errors of using gauges to evaluate satellite precipitation. Coefficients of determination of the fitting are above 0.9 for most metrics. The error function can also be used to estimate the required minimum number of gauges in each grid pixel to meet a predefined error level. This study suggests that the actual quality of satellite precipitation products could be better than conventionally evaluated or expected, and hopefully enables non-subject-matter expert researchers to have better understanding of the explicit uncertainties when using point-scale gauge observations to evaluate areal products. (C) 2018 Elsevier B.V. All rights reserved.
Note24 month embargo; published online: 21 February 2018
VersionFinal accepted manuscript
SponsorsNational Key Research and Development Program of China [2016YFE0102400]; National Natural Science Foundation of China [71461010701, 91437214, 91547210]; NASA [NNH13ZDA001N-NEWS, NNH13ZDA001N-Weather]; National Aeronautics and Space Administration; China Scholarship Council (CSC)