ChinaCropSM1 km: a fine 1 km daily soil moisture dataset for dryland wheat and maize across China during 1993–2018

[摘要] Soil moisture (SM) is a key variable of the regionalhydrological cycle and has important applications for water resource andagricultural drought management. Various global soil moisture products havebeen mostly retrieved from microwave remote sensing data. However, currently there israrely spatially explicit and time-continuous soil moistureinformation with a high resolution at the national scale. In this study, wegenerated a 1 km soil moisture dataset for dryland wheat and maize in China(ChinaCropSM1 km) over 1993–2018 through a random forest (RF) algorithmbased on numerous in situ daily observations of soil moisture. Weindependently used in situ observations (181 327 samples) from theagricultural meteorological stations (AMSs) across China for training (164 202samples) and others for testing (17 125 samples). An irrigation module wasfirst developed according to crop type (i.e., wheat, maize), soil depth(0–10, 10–20 cm) and phenology. We produced four daily datasetsseparately by crop type and soil depth, and their accuracies were allsatisfactory (wheat r 0.93, ubRMSE 0.033 m 3  m −3 ; maize r 0.93, ubRMSE0.035 m 3  m −3 ). The spatiotemporal resolutions and accuracy ofChinaCropSM1 km were significantly better than those of global soil moistureproducts (e.g., r increased by 116 %, ubRMSE decreased by 64 %),including the global remote-sensing-based surface soil moisture dataset(RSSSM) and the European Space Agency (ESA) Climate Change Initiative (CCI)SM. The approach developed in our study could be applied to other regionsand crops in the world, and our improved datasets are very valuable for manystudies and field management, such as agricultural drought monitoring andcrop yield forecasting. The data are published in Zenodo at https://doi.org/10.5281/zenodo.6834530 (wheat 0–10 )(Cheng et al., 2022a), https://doi.org/10.5281/zenodo.6822591 (wheat 10–20 )(Cheng et al., 2022b), https://doi/org/10.5281/zenodo.6822581 (maize 0–10 )(Cheng et al., 2022c) and https://doi.org/10.5281/zenodo.6820166 (maize 10–20 )(Cheng et al., 2022d).

[学科分类] 眼科学