Reduction in 317–780 nm radiance reflected from the sunlit Earth during the eclipse of 21 August 2017

Herman, J. R.; Wen, Guoyong; Marshak, Alexander; Blank, Karin; Huang, Liang; Cede, Alexander; Abuhassan, Nader; Kowalewski, M. G.

doi:10.5194/amt-11-4373-2018

Cited by 5 publications

(9 citation statements)

References 15 publications

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“…The wavelength region from near UV at 388 nm to NIR at 780 nm bears about half of the total solar irradiance of 1,361 W/m 2 (Kopp & Lean, ). The polynomial interpolation of the response of reflectance at five wavelengths is used to estimate the response of spectral reflectance for computing spectral integrated irradiance response, similar to the method by Herman, Wen, et al () for estimating the impact of the solar eclipse on reflected solar irradiance. The percent response of the reflected solar radiance between 388 and 780 nm can be obtained as spectral solar irradiance weighted response as

italicRSP = \frac{\int_{388}^{780} R_{s} ((), λ) F_{0} ((), λ) normald λ}{\int_{388}^{780} F_{0} ((), λ) normald λ} \times 100

where R s ( λ ) is the percent response for wavelength λ estimated from polynomial interpolation from the response at five EPIC wavelengths and F 0 ( λ ) is the TOA spectral solar irradiance.…”

Section: Resultsmentioning

confidence: 99%

“…The near UV at 340 and 388 nm and the visible and the NIR channels allow us to derive aerosol and cloud properties in particular, while the oxygen A and B bands enable us to derive the altitude of cloud and dust plumes (e.g., Davis et al, ; Xu et al, ; Yang et al, ). EPIC images were used to quantify the reduction of reflected sunlight during the 2017 solar eclipse in North America (Herman, Wen, et al, ). Marshak et al () found terrestrial glint over land seen from DSCOVR/EPIC and interpreted the observations of bright flashes as specular reflections off nearly horizontal‐oriented tiny ice platelets floating in the air.…”

Section: Introductionmentioning

confidence: 99%

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A Relationship Between Blue and Near‐IR Global Spectral Reflectance and the Response of Global Average Reflectance to Change in Cloud Cover Observed From EPIC

Wen

Marshak

Song

et al. 2019

Earth and Space Science

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We performed a detailed analysis of Earth Polychromatic Imaging Camera (EPIC) spectral data. We found that the vector composed of blue and near‐infrared (NIR) reflectance follows a counterclockwise closed‐loop trajectory from 0 to 24 UTC as Earth rotates. This nonlinear relationship was not observed by any other satellites due to limited spatial or temporal coverage of either low Earth orbit or geostationary satellites. We found that clouds play an important role in determining the nonlinear relationship in addition to the well‐known cloud‐free land‐ocean reflectance contrast in the two bands. The nonlinear relationship is the result of three factors: (1) a much larger cloud‐free land‐ocean contrast in the NIR band compared to the blue band, (2) significantly larger difference between cloudy land and cloudy ocean reflectance in the NIR band compared to the blue band, and (3) the periodic variation of fractions of clear land, clear ocean, cloudy land, and cloudy ocean in the sunlit hemisphere as Earth rotates. We found that the green vegetation contributes significantly to the NIR global average reflectance when the South and North Americas appear and disappear in the EPIC's field of view. The blue and NIR relationship can be useful for exoplanet research. Clouds impose a strong impact on global spectral reflectance, and the reflectance response to a change in cloud cover depends on whether the change is over land or over the ocean. On average, an increase of 0.1 in cloud coverage will lead to a 7% increase in spectrally integrated global average reflectance.

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italicRSP = \frac{\int_{388}^{780} R_{s} ((), λ) F_{0} ((), λ) normald λ}{\int_{388}^{780} F_{0} ((), λ) normald λ} \times 100

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Relationship Between Blue and Near‐IR Global Spectral Reflectance and the Response of Global Average Reflectance to Change in Cloud Cover Observed From EPIC

Wen

Marshak

Song

et al. 2019

Earth and Space Science

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“…That process requires matching the EPIC and LEO imagers in time and space with the same viewing and illumination conditions. To calibrate the UV channels, Herman et al (2018a) used reflectances measured by the Ozone Mapping and Profiler Suite (OMPS) on the Suomi National Polar-orbiting Partnership (S-NPP) satellite. The VIS/NIR channels outside of the oxygen absorbing bands have been calibrated using reflectances from the MODerate-resolution Imaging Spectroradiometer (MODIS) on the Terra and Aqua platforms and from the S-NPP Visible Infrared Imaging Suite (VIIRS) (Haney et al, 2016;Geogdzhayev and Marshak, 2018;Doelling et al, 2019a;Geogdzhayev et al, 2021).…”

Section: Remote Sensing Instruments On Dscovrmentioning

confidence: 99%

Lagrange Point Missions: The Key to next Generation Integrated Earth Observations. DSCOVR Innovation

Valero

Marshak

Minnis

2021

Front. Remote Sens.

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A new perspective for studying Earth processes has been soundly demonstrated by the Deep Space Climate Observatory (DSCOVR) mission. For the past 6 years, the first Earth-observing satellite orbiting at the Lagrange 1 (L1) point, the DSCOVR satellite has been viewing the planet in a fundamentally different way compared to all other satellites. It is providing unique simultaneous observations of nearly the entire sunlit face of the Earth at a relatively high temporal resolution. This capability enables detailed coverage of evolving atmospheric and surface systems over meso- and large-scale domains, both individually and as a whole, from sunrise to sunset, under continuously changing illumination and viewing conditions. DSCOVR’s view also contains polar regions that are only partially seen from geostationary satellites (GEOs). To exploit this unique perspective, DSCOVR instruments provide multispectral imagery and measurements of the Earth’s reflected and emitted radiances from 0.2 to 100 µm. Data from these sensors have been and continue to be utilized for a great variety of research involving retrievals of atmospheric composition, aerosols, clouds, ocean, and vegetation properties; estimates of surface radiation and the top-of-atmosphere radiation budget; and determining exoplanet signatures. DSCOVR’s synoptic and high temporal resolution data encompass the areas observed during the day from low Earth orbiting satellites (LEOs) and GEOs along with occasional views of the Moon. Because the LEO and GEO measurements can be easily matched with simultaneous DSCOVR data, multiangle, multispectral datasets can be developed by integrating DSCOVR, LEO, and GEO data along with surface and airborne observations, when available. Such datasets can open the door for global application of algorithms heretofore limited to specific LEO satellites and development of new scientific tools for Earth sciences. The utility of the integrated datasets relies on accurate intercalibration of the observations, a process that can be facilitated by the DSCOVR views of the Moon, which serves as a stable reference. Because of their full-disc views, observatories at one or more Lagrange points can play a key role in next-generation integrated Earth observing systems.

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“…3d, e). The Suomi National Polar-orbiting Partnership (Suomi NPP) satellite (Hillger et al, 2013) overpassed the Columbia site at 18:30 UTC when the site was in partial eclipse. The average cloud-top height from Visible Infrared Imaging Radiometer Suite (VIIRS) thermal infrared retrieval around the Columbia site was about 230 mb.…”

Section: Atmospheric and Surface Propertiesmentioning

confidence: 99%

Changes in the surface broadband shortwave radiation budget during the 2017 eclipse

et al. 2020

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Abstract. While solar eclipses are known to greatly diminish the visible radiation reaching the surface of the Earth, less is known about the magnitude of the impact. We explore both the observed and modeled levels of change in surface radiation during the eclipse of 2017. We deployed a pyranometer and Pandora spectrometer instrument to Casper, Wyoming, and Columbia, Missouri, to measure surface broadband shortwave (SW) flux and atmospheric properties during the 21 August 2017 solar eclipse event. We performed detailed radiative transfer simulations to understand the role of clouds in spectral and broadband solar radiation transfer in the Earth's atmosphere for the normal (non-eclipse) spectrum and red-shift solar spectra for eclipse conditions. The theoretical calculations showed that the non-eclipse-to-eclipse surface flux ratio depends strongly on the obscuration of the solar disk and slightly on the cloud optical depth. These findings allowed us to estimate what the surface broadband SW flux would be for hypothetical non-eclipse conditions from observations during the eclipse and further to quantify the impact of the eclipse on the surface broadband SW radiation budget. We found that the eclipse caused local reductions of time-averaged surface flux of about 379 W m−2 (50 %) and 329 W m−2 (46 %) during the ∼3 h course of the eclipse at the Casper and Columbia sites, respectively. We estimated that the Moon's shadow caused a reduction of approximately 7 %–8 % in global average surface broadband SW radiation. The eclipse has a smaller impact on the absolute value of surface flux reduction for cloudy conditions than a clear atmosphere; the impact decreases with the increase in cloud optical depth. However, the relative time-averaged reduction of local surface SW flux during a solar eclipse is approximately 45 %, and it is not sensitive to cloud optical depth. The reduction of global average SW flux relative to climatology is proportional to the non-eclipse and eclipse flux difference in the penumbra area and depends on cloud optical depth in the Moon's shadow and geolocation due to the change in solar zenith angle. We also discuss the influence of cloud inhomogeneity on the observed SW flux. Our results not only quantify the reduction of the surface solar radiation budget, but also advance the understanding of broadband SW radiative transfer under solar eclipse conditions.

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Reduction in 317–780 nm radiance reflected from the sunlit Earth during the eclipse of 21 August 2017

Cited by 5 publications

References 15 publications

A Relationship Between Blue and Near‐IR Global Spectral Reflectance and the Response of Global Average Reflectance to Change in Cloud Cover Observed From EPIC

A Relationship Between Blue and Near‐IR Global Spectral Reflectance and the Response of Global Average Reflectance to Change in Cloud Cover Observed From EPIC

Lagrange Point Missions: The Key to next Generation Integrated Earth Observations. DSCOVR Innovation

Changes in the surface broadband shortwave radiation budget during the 2017 eclipse

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