A new atmospheric dataset for forcing ice–ocean models: Evaluation of reforecasts using the Canadian global deterministic prediction system

Abstract

Despite the availability of several atmospheric reanalyses (e.g. ERA-Interim) there exists both considerable uncertainty in surface forcing fields for ice/ocean modelling and sensitivity to the choice of product used. Here we introduce a relatively high-resolution alternative forcing dataset for ice-ocean models derived from the Canadian Meteorological Centre's (CMC) global deterministic prediction system (GDPS). A set of daily 30 h reforecasts is produced using the GDPS 33 km resolution model providing hourly atmospheric forcing fields for the period 2002-2011. The CMC GDPS reforecasts (CGRF) are compared with ERA-Interim and several observational datasets to evaluate their suitability for forcing ocean models. In particular, the surface temperature, humidity and winds of the CGRF show equivalent biases to those found in ERA-interim. Moreover, the higher resolution of the CGRF permit a more detailed representation of atmospheric structures and topographic steering, resulting in finer-scale coastal features and wind-stress curl. Although the CGRF dataset is not a reanalysis and thus is expected to be less well constrained by available observations, its higher resolution and small bias make it an attractive alternative for forcing ice-ocean models.

A high-resolution ocean and sea-ice modelling system for the Arctic and North Atlantic oceans

“…These include a coupled (atmosphere-ice-ocean) Gulf of Saint Lawrence system (officially operational since June 2011; Smith et al, 2012), the Global Ice-Ocean Prediction System (GIOPS, runs in real time since March 2014; Smith et al, 2015), a Great Lakes coupled system (still in development; Dupont et al, 2012), a regional ice-only prediction system (runs in real time since July 2013; Lemieux et al, 2015a) and a regional Arctic-North Atlantic ice-ocean system based on the CREG12 (Canadian REGional) configuration with a nominal horizontal resolution of 1/12 • . The last is the focus of this paper.…”

“…The long-term objective is to provide Canada with short-term ice-ocean predictions and hazard warnings in ice-infested regions. To evaluate the modelling component (as opposed to the analysis -or data-assimilation -component, which is not covered in this contribution), a series of hindcasts for the period 2003-2009 is carried out, forced at the surface by the Canadian GDPS reforecasts (Smith et al, 2014). These hindcasts test how the model represents upper ocean characteristics and ice cover.…”

Thermodynamic and Dynamic Ice Thickness Changes in the Canadian Arctic Archipelago in NEMO-LIM2 Numerical Simulations

“…Open 25 boundary conditions (temperature, salinity and horizontal ocean velocities) are derived from the monthly GLORYS2v3 product as well. At the surface, the model is driven with high temporal (hourly) and spatial resolution (33 km) atmospheric forcing data provided by Canadian Meteorological Centre (CMC) Global Deterministic Prediction System (GDPS) ReForecasts (CGRF) dataset (Smith et al, 2014), including 10 m wind, 2 m air temperature and humidity, downwelling and longwave radiation flux, and total precipitation. Inter-annual monthly 1…”

“…The CGRF product use the GEWEX correction (more details in Smith et al (2014)) to minimize the bias in the original output from the atmospheric model. However, it was found that this correction is not needed for years after 2011 (Paquin, 2017).…”

Inorganic carbon fluxes on the Mackenzie Shelf of the Beaufort Sea

“…Wind data was taken from the gridded reanalysis data of the Canadian Meteorological Centre (Smith et al, 2014). The location selected is on the Mackenzie Shelf, near the middle of the transect, located at 70.3125° N, 133.5937° W. Figure 6 shows the wind direction and magnitude averaged every six hours through August Sampling of the Mackenzie Shelf transect took place from August 22 nd to 24 th , indicated by the red lines in Fig.…”