PERD Climate Change Impacts on the Energy Sector (CCIES)
Mid-term Workshop, Toronto 22-24 January 2003
Cloud Cover Changes and
Their Impacts on Solar Energy
Production in North America
Sunling Gong
Meteorological Service of Canada
Environment Canada
Solar Energy
Solar energy is to use the solar radiation that
reaches the earth.
The more the cloud cover, the less the solar
energy reaching the surface. Except for the
complex atmospheric processes, it can also be
influenced by the latitude (seasonally ) and
altitude of the spot, and local landscape features
that may block the sun at different times of the
day;
Climate Scenarios
• IPCC climate change scenarios:
– e.g. CCIS – National Climate Scenarios
facility
• Crude on the impact of anthropogenic
aerosols
• Lack of details or regional perspectives
• Local emissions are not well
represented.
Objective
To provide information on the impacts of climate change on the
availability of solar energy in Canada.
(1) Establish the scientific tools to study the impact of cloud
changes on the solar energy availability across Canada under
various climate change scenarios;
(2) Investigate the current cloud cover patterns and trends over
Canada;
(3) Study the impacts of climate change on the availability of
solar energy in Canada using the tool developed by taking into
account more detailed emission information in Canada;
CAM (Canadian Aerosols Module)
NARCM
Model description
• Canadian Regional • Multiple nested grids
Climate Model: CRCM • Resolution: 100km
• CGCM physics • 22 levels
• Canadian Aerosol Model • 12 bins, 4 species size
CAM segregated aerosols.
• Canadian Land Surface
Scheme CLASS
• Explicit Cloud Mode
Experiments and Data
(1) Experiments with/without aerosols are
designed;
(2) NCAR/NCEP reanalysis data (6h) is
used as lateral condition and each
experiment is integrated for 2 years;
(3) Monthly averaged ISCCP cloud cover
data is used for comparison with
simulation.
Cloud cover and SW radiation at the surface
• Before reaching to the surface, the solar radiation can be scattered and
absorbed by clouds, air molecules and aerosols etc..
• Among these factors, clouds are the most important modulator of the
SW flux. Clouds cause complex changes of the radiative energy
exchanges in atmosphere-earth system because of large variation of
their properties over a wide range of space and time scales.
• The simulation of clouds and their seasonal variation was noted as the
major source of uncertainty in atmospheric models (IPCC, 2001)
• The single largest uncertainty in determining the climate sensitivity to
either natural or anthropogenic changes are clouds and their effects on
radiation and their role in the hydrological cycle (IPCC, 2001)
• We focus our attention on the flux at the surface that are less sensitive
to cloud vertical structure.
W m-2
W m-2
Primary results
• Cloud cover and solar radiation distributions in
North America are primarily simulated by NARCM;
• When aerosols are taken into account, comparing
with ISCCP data, ONN can give a good description
of the main characteristics of cloud cover, including
pattern and magnitude, and also a reasonable solar
radiation distribution in North America;
• OFF considerably overestimated the total cloud
cover in North America, especially in northern
territory, including Greenland Island and in western
Atlantic Ocean;
Future work
(1) NARCM with/without will be run for a few more years
to simulate cloud-radiation changes in recent decade.
(2) Under IPCC scenario A1, NARCM with/without
aerosols will be run to simulate the future cloud and
radiation change trends.
(3) Investigate the future trends in solar energy availability
and provide a map of the future solar energy availability
across Canada.