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Data and Products of the High Resolution Ensemble Precipitation Analysis (CaPA-HREPA)

The Canadian Precipitation Analysis system (CaPA) produces an optimal precipitation estimate over 6 and 24 hour accumulation periods. This objective estimate integrates records from precipitation sensors, radar QPEs and a trial field generated by a numerical weather prediction system. Currently, two deterministic configurations of the analysis produce four 6-hour cumulative analyses valid at synoptic times (00, 06, 12, and 18 UTC) and two 24-hour analyses valid at 06 and 12 UTC. The two configurations differ in their domain, and spatial resolution. The Regional Deterministic Precipitation Analysis (RDPA) is connected to the Regional Deterministic Prediction System (RDPS) to derive its trial field with a resolution of 10km. At the same time, the High-Resolution Deterministic Precipitation Analysis (HRDPA) is associated with the national High Resolution Determinstic Prediction System (HRDPS) for its trial field with a resolution of 2.5km.

CaPA-HREPA is the ensemble version of CaPA-HRDPA and provides a 6-hour accumulation analysis of 25 members. The first member of CaPA-HREPA, called the control member, is equivalent to a deterministic analysis (i.e., without data perturbations) and uses the same assimilation approach as CaPA-HRDPA. The other 24 members also follow the same data assimilation approach but use randomly perturbed input data at each analysis time. Thus, each station observation is randomly perturbed by adding a normally distributed error of mean zero and variance (estimated during the assimilation process) equal to the variance of the observation errors. Similarly, the radar QPEs are perturbed by adding an error (constant over the entire spatial coverage of a given radar) sampled from a normal distribution of mean zero and variance, estimated during the assimilation process, equal to the variance of the radar QPE errors. Finally, the perturbed trial fields are provided by CaLDAS-National (Canadian Land Data Assimilation System) and follow a random perturbation in space with no modification to their accumulations.


How to access the data

This experimental data is available on the MSC testing data repository DD-Alpha:

An overview and examples to access and use the Meteorological Service of Canada's open data is available.


The End-User licence for Environment and Climate Change Canada's Data Servers specifies the conditions of use of this data.

MSC Open Data Service Usage Policy

The MSC Open Data Service Usage Policy determines what constitutes an acceptable use of MSC Open Data services and provides users best practices for optimal use.


The metadata of the High Resolution Ensemble Precipitation Analysis [experimental] is available on the Open Government Portal.

Technical documentation


The chronology of changes to the high resolution ensemble version of the Canadian Precipitation Analysis System (CaPA-HREPA) is available here.