A new POWER home page with enhanced responsive GIS-enabled web data services and mapping capabilities replaced the SSE site on June 13, 2018. This current set of SSE web applications and website is no longer accessible. The new POWER will include improved solar and meteorological data with all parameters available on a 0.5-degree global grid. The new home page, featuring the updated parameters, schedule updates and FAQ, can be accessed at POWER.

Please direct any questions to POWER Project Team. You will now be redirected to the new POWER site.

Surface meteorology and Solar Energy
ASDC picture/link Surface meteorology and Solar Energy
A renewable energy resource web site   (release 6.0)
sponsored by NASA's Applied Science Program in the Science Mission Directorate
developed by POWER: Prediction of Worldwide Energy Resource Project
NASA logo
Highlights
  • over 200 satellite-derived meteorology and solar energy parameters
  • monthly averaged from 22 years of data
  • data tables for a particular location
  • GIS Web Mapping Application & Services
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Hint: Under projects select "SSE".
  Data Retrieval:
Meteorology and Solar Energy Meteorology and
  Solar Energy  

  • Data tables for a particular location
    Tables of all SSE data set parameters for a single site.
  • Regional data subsets
    Subsets of data by region.
  • Daily data
    Time series plots and data lists of Insolation and Air Temperature for a single site.
  • Global data sets
    Text files of monthly averaged data for the entire globe. Some annual averages or annual sums are included.
  • Interannual Variability
    Monthly and annual averages by year and for a series of years.
    Web Mapping GIS Web Mapping Application & Services
    Renewable Software Application Inputs Renewable Software
    Application Inputs

      Supporting Documentation:
    Acknowledgement Acknowledgement for data usage
    Geometry Horizontal Grid for
    Input and Output
    Accuracy Accuracy
    Methodology
    Methodology Methodology
    Download the entire document:   SSE_Methodology.pdf (PDF format)
    Free Adobe Reader (PDF Viewer)
    Introduction

    NASA, through its' Science Mission Directorate, has long supported satellite systems and research providing data important to the study of climate and climate processes. These data include long-term estimates of meteorological quantities and surface solar energy fluxes. These satellite and modeled based products have been shown to be accurate enough to provide reliable solar and meteorological resource data over regions where surface measurements are sparse or nonexistent, and offer two unique features - the data is global and, in general, contiguous in time. These two important characteristics, however, tend to generate very large data archives which can be intimidating for commercial users, particularly new users with little experience or resources to explore these large data sets. Moreover the data products contained in the various NASA archives are often in formats that present challenges to new users. To foster the commercial use of the global solar and meteorological data, NASA supported, and continues to support, the development of the Surface meteorology and Solar Energy (SSE) dataset that has been formulated specifically for photovoltaic and renewable energy system design needs. Of equal importance is the access to these data; to this end the SSE parameters are available via user-friendly web-based applications founded on user needs.

    The original SSE data-delivery web site, intended to provide easy access to parameters needed in the renewable energy industry (e.g. solar and wind energy), was released to the public in 1997. The solar and meteorological data contained in this first release was based on the 1993 NASA/World Climate Research Program Version 1.1 Surface Radiation Budget (SRB) science data and TOVS data from the International Satellite Cloud Climatology Project (ISCCP). This initial design approach proved to be of limited value because of the use of "traditional" scientific terminology that was not compatible with terminology/parameters used in the energy industry to design renewable energy power systems. After consultation with industry, SSE Release 2 was made public in 1999 with parameters specifically tailored to the needs of the renewable energy community. Subsequent releases of SSE have continued to build upon an interactive dialog with potential customers resulting in updated parameters using revised NASA data as well as inclusion of new parameters as requested by the user community.

    The Prediction Of Worldwide Energy Resource (POWER) project was initiated in 2003 both to improve subsequent releases of SSE, and to create new datasets applicable to other industries from new satellite observations and the accompanying results from forecast modeling. POWER currently encompasses the SSE data set, tailored for the renewable energy industry, as well as parameters tailored for the sustainable buildings community, and the bio-energy/agricultural industries. In general, the underlying data behind the parameters used by each of these industries is the same - solar radiation and meteorology, including surface and air temperatures, moisture, and winds.

    The purpose of this document is to provide data users of SSE Release 6.0 insight into the underlying source for the solar and meteorological data sets, and to provide additional information relative to the various industry specific parameters, their limitations, and estimated accuracies based on information available to NASA at the time of this document. The intent is to provide information that will enable new and/or long time users to make decisions concerning the suitability of the SSE data for his or her project in a particular region of the globe. And finally, it is noted that SSE Release 6.0 and this document is focused primarily on parameters of interest to the renewable energy industry, although there are many parameters common to both the SSE and Sustainable Buildings components of POWER, and the underlying solar and meteorological data for all three POWER components is derived from common data sources.

    In general, meteorology and solar radiation for SSE Release 6.0 were obtained from the NASA Science Mission Directorate's satellite and re-analysis research programs. Parameters based upon the solar and/or meteorology data were derived and validated based on recommendations from partners in the energy industry. Release 6.0 extends the temporal coverage of the solar and meteorological data from 10 years to more than 22 years (e.g. July 1983 through June 2005) with improved NASA data, and includes new parameters and validation studies.


    Parameters Parameters (Units & Definition)
    Parameter       (Units)
    Definition

    Parameters for Solar Cooking:
    Average insolation       (kWh/m2/day)
    Amount of electromagnetic energy (solar radiation) incident on the surface of the earth. Also referred to as total or global solar radiation.
    Midday insolation       (kWh/m2/day)
    Average insolation available within 1.5 hours of Local Solar Noon.
    Clear sky insolation       (kWh/m2/day)
    Amount of electromagnetic energy (solar radiation) incident on the surface of the earth when the cloud cover is less than 10%.
    Clear sky days       (days)
    Number of clear sky days when the cloud cover is less than 10%.

    Parameters for Sizing and Pointing of Solar Panels and for Solar Thermal Applications:
    Insolation on horizontal surface       (kWh/m2/day)
    Amount of electromagnetic energy (solar radiation) incident on the surface of the earth. Also referred to as total or global solar radiation. The average and percent difference minimum and maximum are given.
    Diffuse radiation on horizontal surface       (kWh/m2/day)
    Amount of electromagnetic energy (solar radiation) incident on the surface of the earth under all-sky conditions with direct radiation from the Sun's beam blocked by a shadow band or tracking disk at the Earth's surface.
    Direct normal radiation       (kWh/m2/day)
    Amount of electromagnetic energy (solar radiation) at the Earth's surface on a flat surface perpendicular to the Sun's beam with surrounding sky radiation blocked.
    Insolation at 3-hourly intervals       (kW/m2)
    Amount of electromagnetic energy (solar radiation) incident on the surface of the earth.
    Insolation clearness index       (dimensionless)
    Fraction of insolation at the top of the atmosphere which reaches the surface of the earth.
    Insolation normalized clearness index       (dimensionless)
    Zenith angle-independent expression of the insolation clearness index.
    Clear sky insolation       (kWh/m2/day)
    Amount of electromagnetic energy (solar radiation) incident on the surface of the earth when the cloud cover is less than 10%.
    Clear sky insolation clearness index       (dimensionless)
    Fraction of insolation at the top of the atmosphere which reaches the surface of the earth during clear sky days (cloud amount < 10%).
    Clear sky insolation normalized clearness index       (dimensionless)
    Zenith angle-independent expression of the clear sky insolation clearness index.

    Solar Geometry:
    Solar Noon       (GMT time)
    The time when the sun is due south in the northern hemisphere or due north in the southern hemisphere.
    Daylight Hours       (hours)
    Time between sunrise and sunset.
    Daylight average of hourly cosine solar zenith angles       (dimensionless)
    The average cosine of the angle between the sun and directly overhead during daylight hours.
    Cosine solar zenith angle at mid-time between sunrise and solar noon       (dimensionless)
    Approximate monthy average ratio of horizontal surface solar beam radiation to direct normal radiation.
    Declination       (degrees)
    The angular distance of the sun north (positive) or south (negative) of the equator.
    Sunset Hour Angle       (degrees)
    The angle that the earth has rotated between the time of solar noon and sunset.
    Maximum solar angle relative to the horizon       (degrees)
    The maximum vertical angle of the sun above the horizon.
    Hourly solar angles relative to the horizon       (degrees)
    The vertical angle of the sun above the horizon.
    Hourly solar azimuth angles       (degrees)
    The arc of the horizon measured clockwise from true north, to the point where a vertical circle through the sun intersects the horizon.

    Parameters for Tilted Solar Panels:
    Radiation on equator-pointed tilted surfaces       (kWh/m2/day)
    Radiation on tilted surfaces is calculated from the monthly average insolation on a horizontal surface. Tilt angles are 0, latitude - 15, latitude, latitude + 15, 90, and the optimum angle. The optimum angle provides the monthly averaged maximum radiation.
    Minimum radiation for equator-pointed tilted surfaces       (kWh/m2/day)
    Radiation on tilted surfaces is calculated from the monthly minimum insolation on a horizontal surface. Tilt angles are 0, latitude - 15, latitude, latitude + 15, 90, and the optimum angle. The optimum angle provides the monthly averaged maximum radiation.
    Maximum radiation for equator-pointed tilted surfaces       (kWh/m2/day)
    Radiation on tilted surfaces is calculated from the monthly maximum insolation on a horizontal surface. Tilt angles are 0, latitude - 15, latitude, latitude + 15, 90, and the optimum angle. The optimum angle provides the monthly averaged maximum radiation.

    Parameters for Sizing Battery or other Energy-storage Systems:
    Minimum available insolation as % of average values over consecutive-day period (1, 3, 7, 14, and 21 days)       (dimensionless)
    This parameter is based on minimum consecutive-day insolation over various numbers of days within the month.
    Horizontal surface deficits below expected average values over consecutive-day period (1, 3, 7, 14, and 21 days)       (kWh/m2)
    Deficits below expected average values over consecutive-day period.
    Equivalent number of NO-SUN days over consecutive-day period (1, 3, 7, 14, and 21 days)       (days)
    Hypothetical number of days for which no solar insolation is available.

    Parameters for Sizing Surplus-product Storage Systems:
    Available surplus as % of average values over consecutive-day period (1, 3, 7, 14, and 21 days)       (dimensionless)
    Available surplus as % of average values over consecutive-day period.

    Cloud Information:
    Daylight cloud amount       (percent)
    Percent of cloud amount during daylight within a region.
    Cloud amount at 3-hourly intervals       (percent)
    Percent of cloud amount within a region.
    Frequency of cloud amount at 3-hourly intervals       (percent)
    Percent of time the cloud amount is less than 10%, between 10 - 70%, and greater than 70% within a region.

    Meteorology (Temperature):
    Air Temperature       (° C)
    Daily Temperature Range       (° C)
    Difference between the average daily maximum and average daily minimum.
    Cooling Degree Days above 18° C       (degree days)
    The monthly accumulation of degrees when the daily mean temperature is above 18° C.
    Heating Degree Days below 18° C       (degree days)
    The monthly accumulation of degrees when the daily mean temperature is below 18° C.
    Arctic Heating Degree Days below 10° C       (degree days)
    The monthly accumulation of degrees when the daily mean temperature is below 10° C.
    Arctic Heating Degree Days below 0° C       (degree days)
    The monthly accumulation of degrees when the daily mean temperature is below 0° C.
    Earth Skin Temperature       (° C)
    The Earth skin temperature is meant to approximate the temperature right at the surface including the vegetated ground coverage. Thus, surfaces with less vegetation will warm in the sunlight than vegetated surfaces and cool more at night.

    Daily Mean Earth Temperature minimum, maximum and amplitude       (° C)

    Frost Days       (days)
    The number of days for which the temperature falls below 0 degrees Celsius.
    Dew/Frost Point Temperature       (° C)
    Temperature at which air is saturated with water vapor.

    Meteorology (Wind):
    Wind speed at 50 m       (m/s)
    The average and percent difference minimum and maximum are given.
    Percent of time for ranges of wind speed at 50 m       (percent)
    Percentage [frequency] of time that wind speed is in each range (0-2, 3-6, 7-10, 11-14, 15-18, 19-25 m/s).
    Wind Speed at 50 m at 3-hourly intervals       (m/s)
    Wind Direction at 50 m       (degrees)
    Wind Direction at 50 m at 3-hourly intervals       (degrees)
    Wind Speed at 10 m for terrain similar to airports       (m/s)
    Wind Speed adjustments for height and vegetation type       (m/s)
    Wind speeds at 50 m may be adjusted to heights from 10 to 300 meters using the Gipe power law. Wind speeds may be adjusted for different terrain by selecting from 17 vegetation types.

    Meteorology (Other):
    Relative Humidity       (percent)
    Ratio of actual partial press of water vapor to the partial pressure at saturation, expressed in percent.
    Specific Humidity       (kg/kg)
    Mass of water vapor carried by unit mass of dry air (kg water/kg dry air).
    Atmospheric Pressure       (kPa)
    Total Column Precipitable Water       (cm)
    Total atmospheric water vapor contained in a vertical column of unit cross-sectional area extending from the surface to the top of the atmosphere.
    Precipitation       (mm/day)
    The average daily rain rate based upon the total monthly averaged amount of rain for the given month divided by the number of days in the month.

    Supporting Information:
    Top-of-atmosphere insolation       (kWh/m2/day)
    Amount of electromagnetic energy (solar radiation) incident at the top of the atmosphere.
    Surface Albedo       (dimensionless)
    Fraction of insolation reflected by the surface of the earth.

    FAQ Frequently Asked Questions (FAQ)
    Submit Questions Do you have a question or comment?
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    Partners and Performance Partners and Performance

    March 29, 2016

    NASA Surface meteorology and Solar Energy Data Sets for Commercial Applications

    Introduction

    Renewable energy technologies are changing the face of the world's energy market. These technologies range in complexity from the introduction of solar ovens and simple photovoltaics panels into rural communities - to the construction of commercial buildings with integrated photovoltaics and large thermal and wind generating power plants. Crucial to the success of the emerging renewable market is the availability of accurate, global solar radiation and meteorology data. The Surface meteorology and Solar Energy (SSE) project is developing the commercial potential of NASA's cloud, radiation, and meteorology data by working closely with partners from government, commercial industry, educational, and non-profit organizations. The SSE data set, which is accelerating the realization of economic and societal benefits from NASA earth science data, is available via the Internet (http://eosweb.larc.nasa.gov/sse/). Currently useful in a number of applications, future versions of these data have the potential to significantly advance the global adoption of renewable energy technologies.

    Estimated uncertainties of most parameters are given in the Accuracy section. Details concerning calculation methods can be found in the Methodology section. The Introduction to the Methodology section is on the web site and the entire document can be downloaded in PDF format.

    Web Site Usage and Performance

    Since June 1999, the SSE web site (Releases 2 through 6) has generated approximately 58,272,154 hits. Approximately 28,474,651 data documents have been downloaded by registered data users. Users include the U.S. Air Force, U.S. State Department Headquarters, U.S. Department of Energy, USDA Forest Service, USGS Headquarters, U.S. Centers for Disease Control, U.S. Army , U.S Navy, EPA Headquarters, National Science Foundation, NOAA, The World Bank, UNESCO , International Finance Corporation, Winrock International, BP Solar, Shell Renewables, Duke Solar Energy, and over 100 U.S. Universities.

    The SSE data set has been incorporated into Solar Energy International's On Line PV Design Course and it has been used by Sun Frost to size solar-powered vaccine refrigerator systems for the World Health Organization. The United Nations Environmental Program (UNEP) and Natural Resources Canada (NRCan) are using SSE data with their greenhouse gas emission's mitigation model to allow calculation of emissions avoided by use of various types of renewable energy power systems over the globe. A CD-ROM consisting of a subset of SSE data and the RETScreen® International software has been developed by NRCan and provided to the UNEP for users in underdeveloped countries that do not have good access to the Internet.
    Monthly plot of SSE hits
    Monthly plot of SSE data distributed

    Release Notes

       Release 1, 2 and 3 -
    The Release 1 web site was scientific in nature. Collaboration with users from the solar energy industry helped to make Release 2 user friendly and understandable to the general renewable energy community. The November 1999 peak in web site usage corresponds to a Natural Resources Canada (NRCan) announcement of the availability of the NASA data for use with their renewable energy software tool RETScreen® International. The software was designed to evaluate the annual energy production, costs, and financial viability of renewable energy technologies. RETScreen® International is becoming an international standard for designers, government agencies, and lending institutions. Canadian supplied ground site data or NASA SSE data are used as inputs. Release 3 became available in October, 2000 and had improved accuracy, higher resolution, and contained additional engineering parameters for the wind, ground-source heat pump, and biomass heating renewable energy technologies. Users defined their own format for both parameter worksheets and color plots.
       Release 4 -
    New solar radiation parameters are diffuse, direct normal, and equator-facing tilted surface radiation calculated from the 10-yr average, minimum, and maximum horizontal surface insolation. Values are given at six different equator-facing tilt angles (latitude, latitude + 15°, latitude - 15°, 0°, 90°, and optimum angle for maximum radiation).

    Wind speed estimates have been improved from values in Release 3, but are still based on height above the ground, snow, water, or ice instead of the effective surface. SSE values will be lower than values based on the effective surface near the tops of vegetation. They are averages over the near-flat, 1°x 1° region with averaged vegetation roughness. Both 50- and 10-meter height values are given. Ten-meter values are for airport-type surfaces only within the average region in the standard data. Ten-meter values for other types of vegetation can be selected as part of the wind parameter listing. Speeds (average, maximum, minimum, diurnal variation, and frequency) and directions (average and diurnal variation) are provided. Wind estimates do not account for localized effects such as topography changes relative to the average height above sea level of the region. They do not account for short-term effects such as storms. Within-region local topography and land-water boundary effects must be accounted for by organizations experienced in those types of analysis. SSE winds are most useful to the hydrology, agriculture, and buildings/architectural communities at the present 1°x 1° spatial resolution. The data may be of use at some renewable energy sites for preliminary design purposes.

    Heating degree day values relative to 0 and 10° C are now provided in addition to values relative to 18° C.

    Three new applications allow users to view the SSE data in different ways.
    • Selected parameters can be downloaded for the entire globe. Monthly and annual averages are provided in 13 columns. The data is easy to import into spreadsheet software.
    • Subsetting of data tables for user defined regions can be done both spatially and temporally.
    • Daily data for each 1°x 1° region provides time series data for any time period from one day to ten years.
       Release 5 -
    Seventy-two solar radiation and cloud parameters were replaced with true 1 x 1 degree data. SSE Release 4 was on a 1 x 1 degree grid interpolated from 2.5 x 2.5 degree data.

    SSE Release 5 horizontal surface insolation values are calculated using version 2.1 of the Pinker and Laszlo algorithm (see SSE Methodology for original algorithm, Ref. [3]) as processed under the NASA/Global Energy and Water Cycle Experiment (GEWEX) Surface Radiation Budget (SRB) project. The International Satellite Cloud Climatology Program (ISCCP) DX data are used as input into the algorithm and to derive the cloud information including cloud diurnal cycle. Additional parameters available to the user and calculated on the fly via the SSE web interface also inherit these improvements.

    A new wind parameter, the Monthly Averaged Wind Speed Adjusted For Height And Vegetation Type, can be calculated for 17 different surface vegetation types and for any height from 10 to 300 meters. The vegetation type and height are specified by the user. The Gipe Power Law is used to calculate a new wind speed from the wind speed at 50 meters above the surface that is computed from output of the Goddard Earth Observing System (GEOS) version 1 analysis. Validation of surface winds using this approach at airports and other surfaces is provided in the SSE Accuracy and Methodology sections. Global/regional plots for wind speed at 100 and 150 meters are also available.

    Another new parameter is monthly averaged precipitation from the Global Precipitation Climatology Project (GPCP) Version 2 Combined Precipitation Data Set.

    Release 5 includes an interface between the SSE data set and the Hybrid Optimization Model for Electric Renewables (HOMER). HOMER software is a Department of Energy National Renewable Energy Laboratory product used by industry to design renewable energy systems around the globe. HOMER seamlessly ingests SSE solar radiation data without a web browser. SSE/HOMER data tables are also presented on the SSE web site.
       Release 6 -
    The temporal span of the SSE data set has been extended from a 10-year period to more than 22 years. The earliest available solar radiation data is for July 1983 and climatological monthly averages have been calculated for the 22-year period beginning in July 1983 and ending in June 2005. The SSE web site offers the SSE data in user friendly formats ranging from daily, monthly, and annual averages for any globally distributed 1-degree region.

    Higher spatial resolution data has been made available from the NASA Goddard Earth Observing System Version 4 reanalysis model (GEOS-4) and the NASA Global Energy and Water Cycle Experiment (GEWEX) Surface Radiation Budget (SRB) project. The GEOS-4 data sets assimilates various in situ and satellite measurements to produce meteorological parameters at the horizontal resolution of 1.0° x 1.25°. The SSE project employed a bilinear interpolation scheme to provide these data products on a uniform grid of 1° x 1°. The GEWEX SRB uses the GEOS-4 temperature and humidity parameters along with satellite cloud information to produce the solar radiation values. All of the parameters are made available through the SSE web site at the 1° x 1° spatial resolution.

    A new web application provides data tables of interannual variability for every one-degree region over the globe. Using this application, any time period from 1983 through 2005 may be chosen. Multi-year averages are calculated for the selected time period, whether the selection is a few years or all 23 available years. Minimum and maximum values are calculated from the difference between the multi-year average and the lowest [highest] value for any single year in the series.

    Industry Contributors

    The following organizations have made significant technical contributions to the success of the SSE project:


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