Thorpex Arctic Weather and Environmental Prediction Initiative

Objectives    |    TAWEPI and THORPEX    |    Projects and principal investigators    |    Contact    |    Documents   |   Franšais    |


Weather and Environmental Prediction (WEP) constitutes one of the most important technological and societal successes of the last century. The positive impact of WEP on health, safety and economic competitiveness is recognized worldwide. The benefit of WEP applications in polar regions has been somewhat delayed due the higher priority of forecasting in the more densely populated southern regions. Concerns about an amplification of anthropogenic climate change at higher latitudes requires a better understanding of weather and climate processes in this region so as to improve our ability to make reliable, quantitative predictions. The International Polar Year (IPY) provides the important international context for a Canadian-led initiative to improve WEP capabilities for the Arctic.

The primary objective of TAWEPI* is to develop and validate a regional Numerical Weather Prediction (NWP) model over the Arctic during the IPY observation period. The proposed experimental model, called Polar-GEM, will be a twin of the Environment Canada (EC) operational regional GEM model, used for one- to two-day weather forecasts. This initiative includes modeling research and data assimilation studies that will help enhance our weather and environmental forecasting capabilities in polar regions and improve our understanding of the Arctic and its influence on world weather. Through improvements in our ability to forecast the Arctic weather, TAWEPI will benefit Canadian communities throughout the Arctic.
* pronounced as tah-weh-pee


THORPEX was established in May 2003 by the Fourteenth World Meteorological Congress as a ten-year international global atmospheric research and development programme under the auspices of the WMO Commission for Atmospheric Sciences. THORPEX is a component of the WMO World Weather Research Programme and was created to reduce and mitigate natural disasters by transforming timely and accurate weather forecasts into specific and definite information in support of decisions that produce the desired societal and economic outcomes.

TAWEPI is part of the THORPEX-IPY cluster, an international cooperation between IPY projects from various countries aiming to explore optimised observations, improve high impact weather forecasts and better understand physical/dynamical processes in polar regions.

Projects and principal investigators

S1. A regional Numerical Weather Prediction (NWP) system over the Arctic – the Polar-GEM system
(Jocelyn Mailhot - EC)

polar-GEMIn this project, a regional (15-km horizontal resolution) NWP system focused over the Arctic basin and surrounding regions (image beside) will be developed. This system will be an extension of the current operational regional GEM model used for short-term forecasts at the Canadian Meteorological Center (CMC).

S1.1 Polar-GEM sea-ice and snow processes (StÚphane Belair, Pierre Pellerin, Paul Vaillancourt - EC)
Particular emphasis will be put on improving the surface processes in the northern latitudes, including: a detailed dynamical-thermodynamic sea-ice model coupled with ocean currents over the Arctic basin; better representation of snow processes and air-sea interaction, using detailed snow models over sea ice, tundras and glaciers/ice caps.

S1.2 Polar-GEM clouds
(Paul Vaillancourt - EC)
The representation of high-latitude clouds, cloud/radiation interactions and other key energy exchanges in the Arctic will also be improved, with the inclusion of a new detailed radiative transfer scheme and from more realistic treatments of ice cloud optical properties.

S2. Data assimilation and sensitivity studies: the role of the Arctic
(Louis Garand - EC)

S2.1 Sensitivity of weather forecasts over the Arctic due to analysis error in the extra-tropics and vice-versa (Mark Buehner and Ayrton Zadra - EC)
This project will focus on using singular vectors (SV) to determine the main factors that can influence the meteorological forecast over the polar regions, and on how the meteorological conditions over those regions can impact the quality of global forecasts on time-scales of one-day to two-weeks.  An SV-based climatology of the Arctic region’s sensitivity to initial and boundary condition errors will be computed.  Also, an SV-based tool will be developed to improve the design of limited-area model (LAM) grids, nesting techniques and targeting strategies.

S2.2 Assimilation of satellite data from polar orbiting satellites (Louis Garand - EC)
Impact studies of the assimilation of hyperspectral infrared radiances from AIRS and IASI with special focus on the Arctic. This will be done in the framework of GEM-Strato (stratospheric version of the GEM model) allowing the assimilation of lower-stratospheric channels.

S2.3 Stratospheric analyses (Saroja Polavarapu - EC)
In this project, a version of the GEM-strato model with online chemistry will be used to generate a time series of analyses during IPY.  These analyses will contribute to the archive of analyses from major meteorological centres being compiled by the SPARC (Stratospheric Processes and their Role in Climate) programme.  The archive will reside at the SPARC data center for future process studies by climatologists.

S3. Sea-ice model development
(Greg Flato, Youyu Lu and Pierre Pellerin - EC)

An important step in the development of the Polar-GEM system is to improve the representation of sea ice at northern latitudes by coupling a detailed dynamical/thermodynamic sea-ice model, eventually including also the ocean currents. The coupled sea-ice modeling work currently underway for the Gulf of St. Lawrence will be extended over the domain of the Polar-GEM in order to include most ice-covered areas in the northern latitudes, i.e. the entire Arctic basin, Hudson Bay, and the Labrador Sea. Further improvements to the sea-ice model used in Polar-GEM will follow from the work of other TAWEPI investigators.

Another important aspect is the availability of high-quality analyses of sea-ice concentrations to serve as forecast initial conditions. A project underway since March, 2007, is producing sea-ice analyses at 5-km horizontal resolution for the Canadian Arctic Archipelago. These analyses will be tested in the framework of Polar-GEM.


List of related presentations and publications

Annual report 2007-2008
Annual report 2008-2009
Annual report 2009-2010


Ayrton Zadra (lead investigator of TAWEPI)
Numerical Prediction Research Division
Environment Canada