Opening Statement
NASA's ASDC has made available the Deep Space Climate Observatory (DSCOVR) Earth Polychromatic Imaging Camera (EPIC) Level 1B version 4 data product. This dataset provides calibrated, 10-channel spectroradiometric imagery of the entire sunlit face of the Earth, enabling science applications including measurements of ozone, aerosols, cloud reflectivity, cloud height, vegetation properties, and ultraviolet (UV) radiation estimates at Earth's surface.
Mission/Campaign/Project Background
The Earth Polychromatic Imaging Camera (EPIC) operating onboard the National Oceanic and Atmospheric Administration's (NOAA) Deep Space Climate Observatory (DSCOVR) spacecraft is a 10-channel spectroradiometer (317–780 nm). The mission's primary objective is to provide a unique angular perspective of Earth from the Earth-Sun Lagrange-1 (L-1) point, enabling continuous full-disk imaging of the entire sunlit face of the Earth. EPIC's position at the L-1 point, combined with its 0.62-degree field of view and 2048×2048 pixel Charge-Coupled Device (CCD) detector coupled to a 30-cm aperture Cassegrain telescope, supports a broad range of Earth science applications. Due to DSCOVR's tilted (Lissajous) orbit about the L-1 point, the apparent angular size of Earth varies from 0.45 to 0.53 degrees within its 6-month orbital period, with a complete set of per-band images captured every 60 to 100 minutes depending on the season.
Data Products
- Accompanying instrument metadata and a series of calibrations and corrections are applied to properly convert the images to Level 1B format. The significant corrections are for flat‐fielding and stray light. Flat-fielding is based on measurements with a uniform light source to measure the differences in sensitivity for each of the 4 million pixels. The resulting correction map is applied to the estimated counts from the CCD. Stray light was measured in the laboratory using a series of small-diameter light sources entering the telescope and imaged on the CCD.
- A similar set of measurements has been performed on orbit using the moon. The illumination of pixels outside the primary diameter of the light source was measured to produce a detailed matrix map of the entire stray light function, and the resulting stray light correction was applied to every image. Other corrections are also used based on laboratory measurements. For wavelengths longer than 550 nm, there are back-to-front interference effects in the partially transparent CCD (etaloning) that must also be removed from measured radiance.
- DSCOVR EPIC Level 1B Version 4 products contain calibrated and geolocated EPIC images of the Earth only (no Moon or dark space objects) in the field of view with ancillary metadata. These data products are in Hierarchical Data Format version 5 (HDF5) format.
| Parameter | Details |
|---|---|
| Spectral Coverage | 317–780 nm (10 narrow-band channels) |
| Detector | 2048×2048 pixel CCD |
| Telescope Aperture | 30-cm Cassegrain |
| Field of View | 0.62 degrees |
| Image Cadence | Every 60–100 minutes (season-dependent) |
| Processing Level | Level 1B |
| File Format | HDF5 |
| Spatial Coverage | Full sunlit disk of Earth |
| Platform Location | Earth-Sun L-1 Lagrange Point |
Access Information
For data access and more information, visit the DSCOVR EPIC Level 1B dataset landing page at Earthdata.
Access Methods
Users can access this data through Earthdahta Search.
User Support
For questions about this data release or assistance with data access, please contact the ASDC User Services team or visit the Earthdata Forum