Bernard Bilodeau

The 15‐km version of the Canadian regional forecast system

Abstract A new mesoscale version of the regional forecast system became operational at the Canadian Meteorological Centre on 18 May 2004. The main changes to the regional modelling system include an increase in both the horizontal and vertical resolutions (15‐km horizontal resolution and 58 vertical levels instead of 24‐km resolution and 28 levels) as well as major upgrades to the physics package. The latter consist of a new condensation package, with an improved formulation of the cloudy boundary layer, a new shallow convection scheme based on a Kuo‐type closure, and the Kain and Fritsch deep convection scheme, together with a subgrid‐scale orography parametrization scheme to represent gravity wave drag and low‐level blocking effects. The new forecast system also includes a few changes to the regional data assimilation such as additional radiance data from satellites. Objective verifications using a series of cases and parallel runs, along with subjective evaluations by CMC meteorologists, indicate significantly improved performance using the new 15‐km resolution forecast system. We can conclude from these verifications that the model exhibits a marked reduction in errors, improved predictability by about 12 hours, better forecasts of precipitation, a significant reduction in the spin‐up time, and a different implicit‐explicit partitioning of precipitation. A number of other features include: sharper precipitation patterns, better representation of trace precipitation, and general improvements of deepening lows and hurricanes. In mountainous regions, several aspects are better represented due to combined higher‐resolution orography and the low‐level blocking term.

Operational Implementation of the ISBA Land Surface Scheme in the Canadian Regional Weather Forecast Model. Part II: Cold Season Results

Abstract The performance of a modified version of the snow scheme included in the Interactions between Surface–Biosphere–Atmosphere (ISBA) land surface scheme, which was operationally implemented into the regional weather forecast system at the Canadian Meteorological Centre, is examined in this study. Stand-alone verification tests conducted prior to the operational implementation showed that ISBAs new snow package was able to realistically reproduce the main characteristics of a snow cover, such as snow water equivalent and density, for five winter datasets taken at Col de Porte, France, and at Goose Bay, Newfoundland, Canada. A number of modifications to ISBAs snow model (i.e., new liquid water reservoir in the snowpack, new formulation of snow density, and melting effect of incident rainfall on the snowpack) were found to improve the numerical representation of snow characteristics. Objective scores for the fully interactive preimplementation tests carried out with the Canadian regional weather fore...

Evaluation of Snowpack Simulations over the Canadian Rockies with an Experimental Hydrometeorological Modeling System

Abstract To improve the representation of the land surface in their operational numerical weather prediction (NWP) models, the Meteorological Research Division of Environment Canada (EC) is developing an external hydrometeorological modeling and data assimilation system. The objective of this study is to verify the improvement in simulating snow cover extent (SCE) and snow water equivalent (SWE) over the Canadian Rockies with this new modeling system. This study will be an important first step in determining the optimal configuration of the land surface model and atmospheric forcing for a future operational implementation. Simulated SCE is compared with the Interactive Multisensor Snow and Ice Mapping System (IMS) analysis, while simulated SWE values are verified against a series of manual snow survey sites located within the Canadian Rockies. Results show that land surface model simulations of SCE and SWE were sensitive to precipitation forcing. Simulations at both low and high resolution forced with EC’...

The Canadian Land Data Assimilation System (CaLDAS): Description and Synthetic Evaluation Study

AbstractThe Canadian Land Data Assimilation System (CaLDAS) has been developed at the Meteorological Research Division of Environment Canada (EC) to better represent the land surface initial states in environmental prediction and assimilation systems. CaLDAS is built around an external land surface modeling system and uses the ensemble Kalman filter (EnKF) methodology. A unique feature of CaLDAS is the use of improved precipitation forcing through the assimilation of precipitation observations. An ensemble of precipitation analyses is generated by combining numerical weather prediction (NWP) model precipitation forecasts with precipitation observations. Spatial phasing errors to the NWP first-guess precipitation forecasts are more effective than perturbations to the precipitation observations in decreasing (increasing) the exceedance ratio (uncertainty ratio) scores and generating flatter, more reliable ranked histograms. CaLDAS has been configured to assimilate L-band microwave brightness temperature TB ...

Development of the 35‐km version of the Canadian regional forecast system

Abstract A new, higher‐resolution version of the regional forecast system was implemented into operations at the Canadian Meteorological Centre during 1995. The new version of the regional finite‐element forecast model is run at 35‐km resolution in the horizontal and 28 sigma levels in the vertical (instead of 50‐km and 25 levels in the previous operational version), with a more advanced physics package. The improved physical parametrizations feature the following: 1) modifications to the treatment of surface processes; 2) changes to the surface layer formulation; 3) an explicit cloud scheme following Sundqvistfor stratiform precipitation; 4) Fritsch‐Chappell scheme for deep convection. The new regional forecast system also includes a pseudo‐analysis of initial soil moisture content based on model error feedback. Both objective and subjective evaluations on case studies and in the parallel runs showed improved performance with the new 35‐km model. The main points from these verifications indicated a signi...

Operational Implementation of the Fritsch-Chappell Convective Scheme in the 24-km Canadian Regional Model

Abstract The objective and subjective evaluations that led to the implementation of the Fritsch and Chappell (FC) convective scheme in the new 24-km Canadian operational regional model are described in this study. Objective precipitation scores computed for a series of 12 benchmark cases equally distributed throughout all seasons and for a parallel preimplementation run of the new version of the model during summer 1998 show the positive impact of increasing the horizontal resolution and of including the FC scheme (instead of the Kuo scheme used in the previous version of the operational model). The comparison is particularly in favor of the FC configuration for the summertime parallel preimplementation run, with improved biases and threat scores, while it is nearly neutral for the 12 benchmark cases comprised mostly of large-scale weather systems. Examination of a summertime case study confirms the superiority of FC over Kuo for the numerical representation of the structure and evolution of mesoscale con...

Near-Surface and Land Surface Forecast System of the Vancouver 2010 Winter Olympic and Paralympic Games

AbstractA high-resolution 2D near-surface and land surface model was developed to produce snow and temperature forecasts over the complex alpine region of the Vancouver 2010 Winter Olympic and Paralympic Games. The model is driven by downscaled operational outputs from the Meteorological Service of Canada’s regional and global forecast models. Downscaling is applied to correct forcings for elevation differences between the operational forecast models and the high-resolution surface model. The high-resolution near-surface and land surface model is then used to further refine the forecasts. The model was validated against temperature and snow depth observations. The largest improvements were found in regions where low-resolution (i.e., on the order of 10 km or more) operational models typically lack the spatial resolution to capture rapid elevation changes. The model was found to better reproduce the intermittent snow cover at low-lying stations and to reduce snow depth error by as much as 3 m at alpine sta...

Assimilation of SMAP brightness temperatures in environment and climate change Canada's new land surface parameterization scheme

The NASA Soil Moisture Active Passive (SMAP) mission was launched in January 2015 and has been providing near global coverage of soil moisture every 3 days. At Environment and Climate Change Canada (ECCC) considerable effort has been focused upon the assimilation of SMAP brightness temperatures for a better analysis of the soil moisture state and resulting Numerical Weather Prediction (NWP) forecasts. A new land-surface parameterization, Soil, Vegetation, and Snow (SVS) was recently developed at ECCC which includes more sophisticated hydrology incorporating multiple soil layers where soil moisture evolves according to Darcian flow, and includes separate energy budgets for different land-surface components. The objectives of this study are to perform a set of assimilation experiments to quantify improvements in soil moisture and added NWP skill from the inclusion of SMAP data within SVS.