EMDNA : Ensemble Meteorological Dataset for North America 1

Probabilistic methods are very useful to estimate the spatial variability in meteorological conditions (e.g., 12 spatial patterns of precipitation and temperature across large domains). In ensemble probabilistic methods, “equally 13 plausible” ensemble members are used to approximate the probability distribution, hence uncertainty, of a spatially 14 distributed meteorological variable conditioned on the available information. The ensemble can be used to evaluate 15 the impact of the uncertainties in a myriad of applications. This study develops the Ensemble Meteorological Dataset 16 for North America (EMDNA). EMDNA has 100 members with daily precipitation amount, mean daily temperature, 17 and daily temperature range at 0.1° spatial resolution from 1979 to 2018, derived from a fusion of station observations 18 and reanalysis model outputs. The station data used in EMDNA are from a serially complete dataset for North America 19 (SCDNA) that fills gaps in precipitation and temperature measurements using multiple strategies. Outputs from three 20 reanalysis products are regridded, corrected, and merged using the Bayesian Model Averaging. Optimal Interpolation 21 (OI) is used to merge stationand reanalysis-based estimates. EMDNA estimates are generated based on OI estimates 22 and spatiotemporally correlated random fields. Evaluation results show that (1) the merged reanalysis estimates 23 outperform raw reanalysis estimates, particularly in high latitudes and mountainous regions; (2) the OI estimates are 24 more accurate than the reanalysis and station-based regression estimates, with the most notable improvement for 25 precipitation occurring in sparsely gauged regions; and (3) EMDNA estimates exhibit good performance according to 26 the diagrams and metrics used for probabilistic evaluation. We also discuss the limitations of the current framework 27 and highlight that persistent efforts are needed to further develop probabilistic methods and ensemble datasets. Overall, 28 EMDNA is expected to be useful for hydrological and meteorological applications in North America. The whole 29 dataset and a teaser dataset (a small subset of EMDNA for easy download and preview) are available at 30 https://doi.org/10.20383/101.0275 (Tang et al., 2020a). 31 https://doi.org/10.5194/essd-2020-303 O pe n A cc es s Earth System Science Data D icu ssio n s Preprint. Discussion started: 17 December 2020 c © Author(s) 2020. CC BY 4.0 License.