Evaluation of Integrated Multi-satellitE Retrievals for GPM (IMERG) over Southern Canada against Ground Precipitation Observations: A Preliminary Assessment

Journal of Hydrometeorology | Asong et al. [2017]


The Global Precipitation Measurement (GPM) mission offers new opportunities for modeling a range of physical/hydrological processes at higher resolutions, especially for remote river systems where the hydrometeorological monitoring network is sparse and weather radar is not readily available. In this study, the recently released Multi-satellitE Retrievals for GPM (V03 IMERG Final Run) product with high spatiotemporal resolution of 0.1°/30 minutes is evaluated against ground-based reference measurements (at six-hourly, daily and monthly time scales) over different terrestrial ecozones of southern Canada within a 23-month period from March 12, 2014 – January 31, 2016. While IMERG and ground-based observations show similar regional variations of mean daily precipitation, IMERG tends to overestimate higher monthly precipitation amounts over the Pacific Maritime ecozone. Results from using continuous as well as categorical skill metrics reveal that IMERG shows more satisfactory agreement at daily and six-hourly time scale for the months of June, July, August and September, unlike November, December, January, February and March. In terms of precipitation extremes (defined by the 75th 36 percentile threshold for reference data), apart from a tendency towards over-detection of heavy precipitation events, IMERG captured well the distribution of heavy precipitation amounts and observed wet/dry spell length distributions over most ecozones. However, low skill was found over large portions of the Montane Cordillera and a few stations on the Prairie ecozone. This early study highlights a potential applicability of V03 IMERG Final Run as a reliable source of precipitation estimates in diverse water resources and hydrometeorological applications for different regions in southern Canada.

Full text can be found here.



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