To harness the sun’s vast energy, grid operators
need an operational resource forecast based on
enhanced data and modeling techniques.
By MeLindA MARquiS, SteVe ALbeRS
SOLAR TODAY®
SEPTEMBER/OCTOBER 2011
VOL. 25, NO. 7
tors, who must constantly balance power supply
and demand, to make better scheduling decisions
about the optimal mix of power generation sources, and to avoid excessive backup reserves.
Forecasts Depend on
Assimilating observations
Modern weather forecasts are derived from
numerical weather prediction (NWP) models,
which are mathematical models of complex
physical processes observed in the atmosphere
and oceans. Current weather conditions — as
determined by observations from sensors on the
Earth’s surface, weather balloons and remote-
sensing instruments, including satellite-borne
sensors — are used to initialize the NWP mod-
els. At defined intervals, such as every hour, new
observations are entered into the models and a
new forecast is produced. The process of updat-
ing the forecast by re-initializing the model with
the latest observations is a type of data assimi-
lation; this approach increases the accuracy of
short-term forecasts and uses large amounts of
computing resources.
Melinda Marquis is the renewable energy program
manager at the NOAA Earth System Research Laboratory (ESRL). She is also the renewable energy lead for
the NOAA Oceanic and Atmospheric Research line
office. She is currently working to develop a NOAA-wide program that provides the atmospheric science and services required for growth of the nation’s
renewable energy industry.
Steve Albers ( steve.albers@noaa.gov) is a research
associate with the Cooperative Institute for Research
in the Atmosphere at Colorado State University. He is a
key developer of the LAPS/STMAS modeling system at
NOAA/ESRL. This system has long had a cloud analysis
and forecast component, and a new solar radiation
capability has recently been added.
Cirrocumulus
Altocumulus
(mackerel sky)
above 18,000 feet
6,000 to 20,000 feet
Cirrus
above 18,000 feet
Altostratus
6,000 to 20,000 feet
Betsy Weatherhead is a senior scientist with the
University of Colorado at Boulder. She is a world-rec-ognized leader in solar radiation, having published
papers in Nature, Science and numerous other journals.
Her work has been featured by Discover magazine, the
BBC, NPR, CNBC and many other news outlets. She
is the recipient of a variety of awards, including the
Pecora Award, and is recognized for her contributions
to the Intergovernmental Panel on Climate Change.
Marquis, Albers and Weatherhead wish to thank the
National Renewable Energy Laboratory’s Dave Renné
for his feedback and consulting on this article.
Stratocumulus
below 6,000 feet
Stratus
below 6,000 feet
Cumulus
below 5,000 feet
Aerosols
UCAr AnD SoLArToDAY.orG
figure 1: To facilitate integration of solar energy into the nation’s grid, the industry needs reliable forecasts
of clouds, water vapor and aerosols.
