TITLE:
Using MAN and Coastal AERONET Measurements to Assess the Suitability of MODIS C6.1 Aerosol Optical Depth for Monitoring Changes from Increased Arctic Shipping
AUTHORS:
Nicole Mölders, Mariel Friberg
KEYWORDS:
Aerosol Optical Depth over the Arctic Ocean, MODIS Evaluation by AERONET and MAN Data, Changes in Arctic Aerosol Optical Depth over the Ocean North of 59.9°N, Arctic Shipping Season Aerosol Optical Depths
JOURNAL NAME:
Open Journal of Air Pollution,
Vol.9 No.4,
December
14,
2020
ABSTRACT: Collocated data of the moderate resolution imaging spectroradiometer (MO-DIS) Collection 6.1
aerosol optical depths (AOD) at 3 km × 3 km north of 59.9°N over
ocean were assessed at 550 nm by aerosol robotic network (AERONET) data from coastal
sites and marine aerosol network (MAN) data from vessels during June to October
2006 to 2018. Typically, MODIS AOD was higher at low and lower at high values than the AERONET AOD. Discrepancies
were largest for sites where the Earth’s surface around the site is very
heterogeneous (Canadian Archipelago, coast of Greenland). Due to the higher
likelihood for sea-ice, MAN and MODIS AOD differed stronger west of Greenland
and over the Beaufort Sea than at location in the Greenland and Norwegian Seas
and Atlantic. MODIS AOD well captured the inter-seasonal variability found in
the AERONET AOD data (R = 0.933). At all sites, MO-DIS and AERONET AOD agreement improved as time
progressed in the shipping season, hinting at errors in sea-ice vs. open water
classification. Overall 75.3% of the MODIS AOD data fell within the limits of
the error envelops of the AERONET/MAN AOD data with MAN ranging between 87.5%
and 100%. Changes in both MODIS and AERONET mean AOD between two periods of
same length (2006-2011, 2013-2018) were explainable by changes in emissions for
all sites.