Extended hindcast of Water Supply Components over Canada/U.S. Transboundary Watersheds based on the CaPA, CaLDAS and GEM systems and coordination with NWS Multi-Precipitation Estimates (MPE)

The Canadian Precipitation Analysis (CaPA) is an operational near real-time gridded precipitation product from Environment Canada available since April 2011 for North America. CaPA has generated a lot of enthusiasm in the Great Lakes area, due to its unique capability of capturing some of the precipitation features that are specific to the Great Lakes, in particular organized shallow convection events which are responsible for lake-effect snowfall. Indeed, because it uses a background field from the Global Environmental Multiscale (GEM) atmospheric model, it can represent the effects that the lakes have on the precipitation patterns, something that is very difficult to catch with the existing precipitation gauging network, as it is entirely over land. During the International Upper Great Lakes Study (IUGLS), it was demonstrated that GEM and CaPA can be used together to obtain skillful estimates of all three components of the net basin supplies (including basin runoff and lake evaporation, in addition to precipitation) at the monthly time scale for the Great Lakes. The objective of this project is to provide the foundations for extending CaPA and GEM hindcasts to 1983. Samples of daily analyses will be provided (one per week from 1995 until 2012). Furthermore, the added value and computing cost of extending the hindcast to either 1983 or 1995 at either 50-km or 15-km resolution will be assessed. This proposal directly supports the GLAM Committee in efforts to improve measurement and understanding of the individual components of the water supply and reduce uncertainty in hydrological conditions which could lead to better forecasting and improvements to regulation of water levels and flows in the Great Lakes- St. Lawrence River system. The project methodology also will be applied outside the Great Lakes basin in other transboundary watersheds along the Canadian-U.S. border.