POWER Data Methodology¶

POWER Project Release History¶

The National Aeronautics and Space Administration (NASA), through its Earth Science research program, has long supported satellite systems and research providing data important to the study of climate and climate processes. These data include long-term climatologically averaged estimates of meteorological quantities and surface solar, and thermal infrared energy, or radiative, fluxes. Additionally, mean values of the base meteorological and solar data are provided in a time series format. These satellite and model-based products have proven to be sufficiently accurate to provide reliable solar and meteorological resource data over regions where surface measurements are sparse or nonexistent. The products offer two unique features: the data is global and generally contiguous in space and time. These two important characteristics tend to generate exceptionally large data archives which can be intimidating for users, particularly those 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 usage of global solar and meteorological data, NASA’s Earth Science to Action program within the Earth Science Division supports the development and release of user-friendly data sets formulated specifically for designated user communities with access to these data via a user-friendly web-based mapping portal.

The Surface meteorology and Solar Energy (SSE) project was one of the earlier activities funded under a previous NASA Applied Science Program to foster use of NASA’s data holdings. The SSE data-delivery website was focused on providing easy access to parameters valued in the renewable energy industry and was initially released 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 TIROS Operational Vertical Sounder (TOVS) data from the International Satellite Cloud Climatology Project (ISCCP). Release 2 of SSE was made public in 1999 with parameters specifically tailored to the needs of the renewable energy community. Subsequent releases of SSE (SSE-Release 3.0 in 2000, SSE-Release 4.0 in 2003, SSE-Release 5.0 in 2005, and SSE-Release 6.0 in 2008) have continued to build upon an interactive dialog with potential customers resulting in updated parameters using the most recent NASA data as well as inclusion of new parameters that have been requested by the user community.

The POWER Project was initiated in 2002 as an outgrowth of the SSE project. The initial POWER Project encompassed the SSE component and added two new data sets with applicability to the architectural (e.g. Sustainable Buildings) and agricultural (e.g. Agroclimatology) industries, with the continuing objective of improvements to and expansion of the focused parameters included in each section of POWER.

Upgrades to the SSE component of POWER included adding Geographic Information System (GIS) functionality to the data ordering/access process. SSE-GIS constituted the Release 7.0 version, but also provided updated data sets.

POWER Release 8 aggregated the three focused data components of POWER: SSE, Sustainable Building, and Agroclimatology into a new responsive data portal designed to fit on desktop, tablet, and smart phone platforms. Additional upgrades included geospatially enabled online tools to facilitate data ordering, viewing, and analysis of the solar and meteorological data. The meteorological data/parameters in POWER Release 8 were based upon Goddard’s Global Modeling and Assimilation Office (GMAO) Modern Era Retrospective-Analysis for Research and Applications (MERRA-2) assimilation model products and GMAO Forward Processing – Instrument Teams (FP-IT) GEOS 5.12.4 near-real time products. MERRA-2 data spans the time period from 1981 to within several months of real time; GEOS 5.12.4 data covers the time period from the end of the MERRA-2 data stream to within several days of real time. MERRA-2 and GEOS 5.12.4 algorithm versions are essentially the same which results in minimal discontinuities between the different assimilation models. The solar based data/parameters in POWER Release 8 were based upon satellite observations with subsequent inversion to surface solar insolation by NASA’s Global Energy and Water Exchange Project (GEWEX) /Surface Radiation Budget (SRB) Release 3 and NASA’s CERES Fast Longwave And Shortwave Radiative project (FLASHFlux).

POWER Release 9 built upon the data portal established with Release 8, but added data releases from NASA's SRB Release 4, CERES SYN1deg, and FLASHFlux Version 4A. The data/parameters in POWER Release 9 are provided on a global grid with spatial resolutions equal to the input data. That resolution is 1.0° latitude by 1.0° longitude for the radiation data sets and ½° latitude by ⅝° longitude for the meteorological data sets. The grid reference system is WGS84. An additional improvement over previous version is the inclusion of hourly data for certain parameters.

POWER Release 10¶

POWER Release 10 enhances the data pipeline by fully migrating to a cloud-based data processing pipeline. Each source has an independent data processing pipeline implementing improvements, decreasing processing latencies, improving temporal coverage, and much more.

Meteorological parameters continue to be based upon MERRA-2 and GEOS FP-IT assimilation models.

Sections under "Data Sources and Validation", listed in the left menu in this methodology, provide summaries of the sources and estimated uncertainty associated with the data underlying the solar and meteorological parameters available through POWER. The uncertainty estimates are based upon comparisons with surface measurements. Additionally, procedures for computing value-added parameters are detailed under the "Derived and Adjusted Data" heading in the left menu.

High-Resolution Sources¶

POWER integrates several higher-resolution NASA sources alongside the primary archive. These are exposed through the High-Resolution toggle in the DAV and through dedicated parameter aliases in the API.

Components¶

While many of the sources of POWER data contain parameters that cross these boundaries of component type, the following links give overviews of the sources and parameters: