WindScan
Encyclopedia
WindScan contains globally gridded, high resolution offshore wind speeds and directions on a 0.250 global grid and multiple time resolutions down to 6 hourly measurements. With 22 years of wind speed
and directional data derived from multiple satellite
measurements, WindScan provides weather risk analysis as well as site specific resource analysis for any offshore site in the world, whilst the 0.25° resolution allows analysis of differences in wind speed between sites, for example within individual offshore wind energy
development zones.
The utilisation of multiple satellite measurements fills in the data gaps (in both space and time) of individual satellite samplings and reduces the subsampling aliases and random errors.
WindScan development was in response to the high demand for high resolution wind speed and direction data from the offshore wind energy industry. For example, developers want to make more accurate forecasts of offshore life cycle wind power
output and annual variability/site climatology
.
s of 6 hours, 12 hours and daily have become feasible since mid 2002, mid 1995 and January 1991, respectively (with 75% time coverage and 90% spatial coverage between 650S–650N). If the coverage is relaxed, the feasible times can be extended to earlier periods.
(DMSP) satellite in July 1987 to the constellation of 5 US satellites since 2000.
In situ observations still play a critical role in calibrating and validating satellite observations. However, with the dense satellite sampling, in-situ observations play a minor role in reducing random and sampling errors in blended analyses using satellite observations .
The short-lived wind satellites are not used (e.g., the US National Aeronautics and Space Agency Scatterometer
(NSCAT), the joint US/Japan SeaWinds on the Advanced Earth Observing Satellites (ADEOS I and ADEOS II
), non-US satellites (e.g. the European Remote Sensing Satellites (ERS) 1 and 2, which have narrow observing swaths and interrupted observations), and satellites from which sea surface wind speed can also be retrieved (presently with less accuracy) along with the primary product of sea level (e.g. the joint US/French altimetry satellites of Ocean Topography Experiment (TOPEX/Poseidon
) and the follow-on Jason 1
). Inclusion of these data would have limited positive impact for the corresponding time periods on the blended product.
Among the satellites used, the passive DMSP observations are from the microwave radiometers on the Special Sensor Microwave Imager (SSMI ). Later additions to these passive microwave observations are the Tropical Rainfall Measuring Mission
(TRMM) Microwave Imager (TMI ) and the Advanced Microwave Scanning Radiometer of NASA
’s Earth Observing System (Aqua (satellite)
) AMSR-E . The scatterometer (e.g. the Quick Scatterometer (QuikSCAT
)), which is active by nature, uses microwave radar and retrieves both wind speed and wind direction .
At the temporal resolution of 12 hourly, one satellite provides data coverage to less than 30% of the oceanic grid boxes.
The addition of the second SSMI satellite drastically increases the spatial coverage to just below 75%.
With three or more satellites, the spatial coverage increases to above 95%.
At the temporal resolution of 6 hourly, the spatial coverage is less than 30% with two or fewer satellites.
The coverage is about 42% with the three SSMI satellites.
With the addition of the TMI, the spatial coverage increases to about 56%.
The addition of the QuikSCAT
further increases the spatial coverage to about 66%. This modest increase is due to the close sampling times of the QuikSCAT
and the SSMI satellites, although their ascending and descending tracks are out-of-phase.
However, the addition of the AMSR-E dramatically increases the spatial coverage to above 90%. The critical importance of the AMSR-E for high resolution products (6 hourly in this case) is due to its unique sampling times compared to the other satellites.
Following this satellite data blending process, on the global 0.250 grid, blended products with temporal resolutions of 6 hours, have become feasible.
output from different development areas in the North Sea
. This has a large impact on the European wind farm
industry. Different zones in the North Sea at the same distance from the coastline can give power outputs which differ by over 40%. Even within a single zone the energy yield can differ by up to 13% depending on the location chosen for development .
The blended satellite data has also been used to generate a global rank of the offshore wind resource at current offshore wind farms .
Wind speed
Wind speed, or wind velocity, is a fundamental atmospheric rate.Wind speed affects weather forecasting, aircraft and maritime operations, construction projects, growth and metabolism rate of many plant species, and countless other implications....
and directional data derived from multiple satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
measurements, WindScan provides weather risk analysis as well as site specific resource analysis for any offshore site in the world, whilst the 0.25° resolution allows analysis of differences in wind speed between sites, for example within individual offshore wind energy
Wind energy
Wind energy is the kinetic energy of air in motion; see also wind power.Total wind energy flowing through an imaginary area A during the time t is:E = ½ m v2 = ½ v 2...
development zones.
The utilisation of multiple satellite measurements fills in the data gaps (in both space and time) of individual satellite samplings and reduces the subsampling aliases and random errors.
WindScan development was in response to the high demand for high resolution wind speed and direction data from the offshore wind energy industry. For example, developers want to make more accurate forecasts of offshore life cycle wind power
Wind power
Wind power is the conversion of wind energy into a useful form of energy, such as using wind turbines to make electricity, windmills for mechanical power, windpumps for water pumping or drainage, or sails to propel ships....
output and annual variability/site climatology
Climatology
Climatology is the study of climate, scientifically defined as weather conditions averaged over a period of time, and is a branch of the atmospheric sciences...
.
Assessment of composite global sea surface wind speeds
Global 0.250 gridded, blended products with temporal resolutionTemporal resolution
Temporal resolution refers to the precision of a measurement with respect to time. Often there is a tradeoff between temporal resolution of a measurement and its spatial resolution. This trade-off can be attributed to the finite speed of light and the fact that it takes a certain period of time...
s of 6 hours, 12 hours and daily have become feasible since mid 2002, mid 1995 and January 1991, respectively (with 75% time coverage and 90% spatial coverage between 650S–650N). If the coverage is relaxed, the feasible times can be extended to earlier periods.
Sea surface wind speed observations
Sea surface wind has been traditionally observed from platforms such as ships and buoys. However, even today, observations still have very limited spatial coverage over the ocean surface. Sea surface wind speed has also been operationally observed from satellite sensors, starting with a US Defense Meteorological Satellite ProgramDefense Meteorological Satellite Program
The Defense Meteorological Satellite Program monitors meteorological, oceanographic, and solar-terrestrial physics for the United States Department of Defense. The program is now run by the National Oceanic and Atmospheric Administration. The mission of the satellites was revealed in March 1973...
(DMSP) satellite in July 1987 to the constellation of 5 US satellites since 2000.
In situ observations still play a critical role in calibrating and validating satellite observations. However, with the dense satellite sampling, in-situ observations play a minor role in reducing random and sampling errors in blended analyses using satellite observations .
The short-lived wind satellites are not used (e.g., the US National Aeronautics and Space Agency Scatterometer
Scatterometer
A radar scatterometer is designed to determine the normalized radar cross section of the surface. Scatterometers operate by transmitting a pulse of microwave energy towards the Earth's surface and measuring the reflected energy. A separate measurement of the noise-only power is made and...
(NSCAT), the joint US/Japan SeaWinds on the Advanced Earth Observing Satellites (ADEOS I and ADEOS II
ADEOS II
ADEOS II was an Earth observation satellite launched by NASDA, NASA and CNES in December 2002. Its Japanese name was Midori 2, and it was the successor to the 1996 mission ADEOS I...
), non-US satellites (e.g. the European Remote Sensing Satellites (ERS) 1 and 2, which have narrow observing swaths and interrupted observations), and satellites from which sea surface wind speed can also be retrieved (presently with less accuracy) along with the primary product of sea level (e.g. the joint US/French altimetry satellites of Ocean Topography Experiment (TOPEX/Poseidon
TOPEX/Poseidon
Launched in 1992, TOPEX/Poseidon was a joint satellite mission between NASA, the U.S. space agency, and CNES, the French space agency, to map ocean surface topography. The first major oceanographic research vessel to sail into space, TOPEX/Poseidon helped revolutionize oceanography by proving the...
) and the follow-on Jason 1
Jason 1
Jason-1 is a satellite oceanography mission to monitor global ocean circulation, study the ties between the ocean and the atmosphere, improve global climate forecasts and predictions, and monitor events such as El Niño and ocean eddies....
). Inclusion of these data would have limited positive impact for the corresponding time periods on the blended product.
Among the satellites used, the passive DMSP observations are from the microwave radiometers on the Special Sensor Microwave Imager (SSMI ). Later additions to these passive microwave observations are the Tropical Rainfall Measuring Mission
Tropical Rainfall Measuring Mission
The Tropical Rainfall Measuring Mission is a joint space mission between NASA and the Japan Aerospace Exploration Agency designed to monitor and study tropical rainfall. The term refers to both the mission itself and the satellite that the mission uses to collect data...
(TRMM) Microwave Imager (TMI ) and the Advanced Microwave Scanning Radiometer of NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
’s Earth Observing System (Aqua (satellite)
Aqua (satellite)
Aqua is a multi-national NASA scientific research satellite in orbit around the Earth, studying the precipitation, evaporation, and cycling of water. It is the second major component of the Earth Observing System preceded by Terra and followed by Aura .The name "Aqua" comes from the Latin word...
) AMSR-E . The scatterometer (e.g. the Quick Scatterometer (QuikSCAT
QuikSCAT
The QuikSCAT is an earth-observing satellite that provided estimates of wind speed and direction over the oceans to National Oceanic and Atmospheric Administration and others. This "quick recovery" mission intended to replace the NASA Scatterometer , which failed in June 1997...
)), which is active by nature, uses microwave radar and retrieves both wind speed and wind direction .
Summary of data coverage
At the temporal resolution of daily, one SSMI satellite provides data coverage over about 75% of the global 0.250 oceanic boxes between 650S–650N. With two or more satellites, the spatial coverage increases to about 100%.At the temporal resolution of 12 hourly, one satellite provides data coverage to less than 30% of the oceanic grid boxes.
The addition of the second SSMI satellite drastically increases the spatial coverage to just below 75%.
With three or more satellites, the spatial coverage increases to above 95%.
At the temporal resolution of 6 hourly, the spatial coverage is less than 30% with two or fewer satellites.
The coverage is about 42% with the three SSMI satellites.
With the addition of the TMI, the spatial coverage increases to about 56%.
The addition of the QuikSCAT
QuikSCAT
The QuikSCAT is an earth-observing satellite that provided estimates of wind speed and direction over the oceans to National Oceanic and Atmospheric Administration and others. This "quick recovery" mission intended to replace the NASA Scatterometer , which failed in June 1997...
further increases the spatial coverage to about 66%. This modest increase is due to the close sampling times of the QuikSCAT
QuikSCAT
The QuikSCAT is an earth-observing satellite that provided estimates of wind speed and direction over the oceans to National Oceanic and Atmospheric Administration and others. This "quick recovery" mission intended to replace the NASA Scatterometer , which failed in June 1997...
and the SSMI satellites, although their ascending and descending tracks are out-of-phase.
However, the addition of the AMSR-E dramatically increases the spatial coverage to above 90%. The critical importance of the AMSR-E for high resolution products (6 hourly in this case) is due to its unique sampling times compared to the other satellites.
Following this satellite data blending process, on the global 0.250 grid, blended products with temporal resolutions of 6 hours, have become feasible.
Research findings using WindScan
Recent research undertaken using WindScan has shown significant differences in wind powerWind power
Wind power is the conversion of wind energy into a useful form of energy, such as using wind turbines to make electricity, windmills for mechanical power, windpumps for water pumping or drainage, or sails to propel ships....
output from different development areas in the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
. This has a large impact on the European wind farm
Wind farm
A wind farm is a group of wind turbines in the same location used to produce electric power. A large wind farm may consist of several hundred individual wind turbines, and cover an extended area of hundreds of square miles, but the land between the turbines may be used for agricultural or other...
industry. Different zones in the North Sea at the same distance from the coastline can give power outputs which differ by over 40%. Even within a single zone the energy yield can differ by up to 13% depending on the location chosen for development .
The blended satellite data has also been used to generate a global rank of the offshore wind resource at current offshore wind farms .