6 research outputs found
Characterization and application of artificial light sources for nighttime aerosol optical depth retrievals using the Visible Infrared Imager Radiometer Suite Day/Night Band
Using nighttime observations from Visible Infrared Imager Radiometer Suite (VIIRS) Day/Night band (DNB), the characteristics of artificial light sources are evaluated as functions of observation conditions, and incremental improvements are documented on nighttime aerosol retrievals using VIIRS DNB data on a regional scale. We find that the standard deviation of instantaneous radiance for a given artificial light source is strongly dependent upon the satellite viewing angle but is weakly dependent on lunar fraction and lunar angle. Retrieval of nighttime aerosol optical thickness (AOT) based on the novel use of these artificial light sources is demonstrated for three selected regions (United States, Middle East and India) during 2015. Reasonable agreement is found between nighttime AOTs from the VIIRS DNB and temporally adjacent daytime AOTs from the AErosol RObotic NETwork (AERONET) as well as from coincident nighttime AOT retrievals from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), indicating the potential of this method to begin filling critical gaps in diurnal AOT information at both regional and global scales. Issues related to cloud, snow and ice contamination during the winter season, as well as data loss due to the misclassification of thick aerosol plumes as clouds, must be addressed to make the algorithm operationally robust
Ozone Monitoring Instrument (OMI) UV aerosol index data analysis over the Arctic region for future data assimilation and climate forcing applications
Due to a lack of high-latitude ground-based and
satellite-based data from traditional passive- and active-based
measurements, the impact of aerosol particles on the Arctic region is one of
the least understood factors contributing to recent Arctic sea ice changes.
In this study, we investigated the feasibility of using the ultraviolet (UV)
aerosol index (AI) parameter from the Ozone Monitoring Instrument (OMI), a
semi-quantitative aerosol parameter, for quantifying spatiotemporal changes
in UV-absorbing aerosols over the Arctic region. We found that OMI AI data
are affected by an additional row anomaly that is unflagged by the OMI quality
control flag and are systematically biased as functions of observing
conditions, such as azimuth angle, and certain surface types over the Arctic
region, resulting in an anomalous “ring” of climatologically high AI
centered at about 70∘ N, surrounding an area of low AI over the pole.
Two methods were developed in this study for quality-assuring the Arctic AI
data. Using quality-controlled OMI AI data from 2005 through 2020, we found
decreases in UV-absorbing aerosols in the spring months (April and May) over
much of the Arctic region and increases in UV-absorbing aerosols in the
summer months (June, July, and August) over northern Russia and northern
Canada. Additionally, we found significant increases in the frequency and
size of UV-absorbing aerosol events across the Arctic and high-Arctic (north
of 80∘ N) regions for the latter half of the study period
(2014–2020), driven primarily by a significant increase in boreal
biomass-burning plume coverage.</p