Sensitivity studies of nighttime top-of-atmosphere radiances from artificial light sources using a 3-D radiative transfer model for nighttime aerosol retrievals
<p>By accounting for surface-based light source emissions and top-of-atmosphere (TOA) downward lunar fluxes, we adapted the spherical harmonics discrete ordinate method (SHDOM) 3-dimensional (3-D) radiative transfer model (RTM) to simulate nighttime 3-D TOA radiances as observed from the Visib...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-05-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://amt.copernicus.org/articles/16/2531/2023/amt-16-2531-2023.pdf |
| Summary: | <p>By accounting for surface-based light source emissions and
top-of-atmosphere (TOA) downward lunar fluxes, we adapted the spherical
harmonics discrete ordinate method (SHDOM) 3-dimensional (3-D) radiative
transfer model (RTM) to simulate nighttime 3-D TOA radiances as observed
from the Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band
(DNB) on board the Suomi-NPP satellite platform. Used previously for daytime
3-D applications, these new SHDOM enhancements allow for the study of the
impacts of various observing conditions and aerosol properties on simulated
VIIRS-DNB TOA radiances. Observations over Dakar, Senegal, selected for its
bright city lights and a large range of aerosol optical depth (AOD), were
investigated for potential applications and opportunities for using observed radiances containing VIIRS-DNB “bright pixels” from artificial light sources to conduct aerosol retrievals. We found that using the standard deviation (SD) of such bright pixels provided a more stable quantity for nighttime AOD retrievals than direct retrievals from TOA radiances. Further, both the
mean TOA radiance and SD of TOA radiances over artificial sources are
significantly impacted by satellite viewing angles. Light domes, the
enhanced radiances adjacent to artificial light sources, are strong
functions of aerosol properties and especially aerosol vertical distribution, which may be further utilized for retrieving aerosol layer
height in future studies. Through inter-comparison with both day- and
nighttime Aerosol Robotic Network (AERONET) data, the feasibility of
retrieving nighttime AODs using 3-D RTM SHDOM over artificial light sources
was demonstrated. Our study shows strong potential for using artificial
light sources for nighttime AOD retrievals, while also highlighting larger
uncertainties in quantifying surface light source emissions. This study
underscores the need for surface light emission source characterizations as
a key boundary condition, which is a complex task that requires enhanced
input data and further research. We demonstrate how quality-controlled
nighttime light data from the NASA's Black Marble product suite could serve
as a primary input into estimations of surface light source emissions for
nighttime aerosol retrievals.</p> |
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| ISSN: | 1867-1381 1867-8548 |