Thorpex Arctic Weather and Environmental Prediction Initiative
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.
* pronounced as tah-weh-pee
- 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.
TAWEPI and 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.
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)
In 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)
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
S1.2 Polar-GEM clouds (Paul Vaillancourt - EC)
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)
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
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)
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.
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.
ContactAyrton Zadra (lead investigator of TAWEPI)
Numerical Prediction Research Division