ASDC | DSCOVR_EPIC_L1A

DSCOVR Level 1A

Entry Title: DSCOVR EPIC L1A Version 2

Entry ID: DSCOVR_EPIC_L1A_2

Radiation Budget

Description

Deep Space Climate Observatory (DSCOVR) Earth Polychromatic Imaging Camera (EPIC).

EPIC is a 10-channel spectro-radiometer (317 – 780 nm) onboard NOAA’s 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 UV radiation estimates at Earth's surface.

EPIC provides 10 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 of 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 properly convert the images to Level 1A format. The major 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 main 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 is applied to every image. Other corrections are also applied 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 geo-location information. These data products are in HDF5 format.

DOI

10.5067/EPIC/DSCOVR/L1A.002

VIEW RELATED INFORMATION

ALGORITHM DOCUMENTATION

DATA CITATION GUIDELINES

How to cite ASDC data

INSTRUMENT/SENSOR CALIBRATION DOCUMENTATION

DSCOVR Earth Science Instrument Overview
EPIC level 1 A & Calibration factors table

MICRO ARTICLE

PROCESSING HISTORY

EPIC Data Format Control Book Specification July 1, 2016

Earth Observation Portal Page for DSCOVR Mission Information

USER FEEDBACK PAGE

NASA Goddard Twitter Page

From GCMD Science Keywords:

ATMOSPHERIC RADIATION
SOLAR IRRADIANCE

318nm
325nm
340nm
388nm
443nm
551nm
680nm
688nm
764nm
780nm
Imagery
Lagrange

Data Distribution

Current Products

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Spatial Information

Spatial Coverage: (S: -90, N: 90), (W: -180, E: 180)
Spatial Coverage Type: Not provided
Horizontal Resolution Range: None
Coordinate System: Cartesian
Granule Spatial Representation: Cartesian

Locations

SOUTHERN OCEAN GLOBAL

Temporal Information

Temporal Coverage: 2015-06-12 - 2019-09-13

Platforms

Solar/Space Observation Satellites

DSCOVR

Deep Space Climate Observatory

CCD IMAGER

Charge-Coupled Device

Metadata Dates

Created on 2017-06-28

Last updated on 2020-08-25