ASDC | DSCOVR_EPIC_L1A

DSCOVR Level 1A

Entry Title: DSCOVR EPIC Level 1A Version 3

Entry ID: DSCOVR_EPIC_L1A_3

Radiation Budget

Description

Deep Space Climate Observatory (DSCOVR) Earth Polychromatic Imaging Camera (EPIC) is a 10-channel spectro-radiometer (317 – 780 nm) onboard the National Oceanic and Atmospheric Administration's (NOAA) DSCOVR spacecraft located at the Earth-Sun Lagrange-1 (L-1) point giving EPIC a unique angular perspective that is used in science applications to measure ozone, aerosols, cloud reflectivity, cloud height, vegetation properties, and ultraviolet (UV) radiation estimates at Earth's surface. EPIC provides ten narrow-band spectral images of the entire sunlit face of the Earth using a 2048x2048 pixel CCD (Charge Coupled Device) detector coupled to a 30-cm aperture Cassegrain telescope. EPIC collects radiance data from the Earth and other sources through the Camera/Telescope Assembly. EPIC has a field of view (FOV) of 0.62 degrees, sufficient to image the entire Earth. Because of DSCOVR's tilted (Lissajous) orbit about the L‐1 point, the apparent angular size of the Earth varies from 0.45 to 0.53 degrees within its 6-month orbital period. Depending on the season, a complete set of per-band images is taken every 60 to 100 minutes.

Accompanying instrument metadata and a series of calibrations and corrections are applied to convert the images to Level 1A format properly. 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 measured 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 the measured radiances.

The Level 1A products contain calibrated EPIC images with ancillary metadata and geolocation information. These data products are in HDF5 format.

DOI

10.5067/EPIC/DSCOVR_L1A_03

Citation Styles for this Dataset

Resources and Documentation

Earthdata Forum

PROJECT HOME PAGE

VIEW RELATED INFORMATION

ALGORITHM DOCUMENTATION

INSTRUMENT/SENSOR CALIBRATION DOCUMENTATION

EPIC level 1 A & B Calibration factors table

PROCESSING HISTORY

EPIC Data Format Control Book Specification, Version 3, September 19, 2018

From GCMD Science Keywords:

SOLAR IRRADIANCE
ATMOSPHERIC RADIATION
ATTITUDE CHARACTERISTICS

Data Distribution

File Format(s):

HDF5

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Spatial Information

Spatial Coverage: (S: -90, N: 90), (W: -180, E: 180)
Spatial Coverage Type: Not provided
Coordinate System: Cartesian
Granule Spatial Representation: Cartesian

Locations

GLOBAL

Temporal Information

Temporal Coverage: 2015-06-13 - Present

Platforms

Solar/Space Observation Satellites

DSCOVR

Deep Space Climate Observatory

CCD IMAGER

Metadata Dates

Created on 2019-09-13

Last updated on 2023-08-17