A novel method of identifying and analysing oil smoke plumes based on MODIS and CALIPSO satellite data
Authors: Mereuţă Alexandru , Ajtai Nicolae , Radovici Andrei T. , Papagiannopoulos Nikolaos , Deaconu Lucia T. , Botezan Camelia S. , Ştefănie Horaţiu I. , Nicolae Doina , Ozunu Alexandru 
Published: April 2022

Abstract. Black carbon aerosols are the second largest contributor
to global warming while also being linked to respiratory and cardiovascular
disease. These particles are generally found in smoke plumes originating
from biomass burning and fossil fuel combustion. They are also heavily
concentrated in smoke plumes originating from oil fires, exhibiting the
largest ratio of black carbon to organic carbon. In this study, we
identified and analysed oil smoke plumes derived from 30 major industrial
events within a 12-year timeframe. To our knowledge, this is the first study
of its kind that utilized a synergetic approach based on satellite remote
sensing techniques. Satellite data offer access to these events, which, as
seen in this study, are mainly located in war-prone or hazardous areas. This
study focuses on the use of MODIS (Moderate Resolution Imaging
Spectroradiometer) and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder
Satellite Observations) products regarding these types of aerosol while also
highlighting their intrinsic limitations. By using data from both MODIS
instruments on board Terra and Aqua satellites, we addressed the temporal
evolution of the smoke plume while assessing lidar-specific properties and
plume elevation using CALIPSO data. The analysis method in this study was
developed to better differentiate between oil smoke aerosols and the local
atmospheric scene. We present several aerosol properties in the form of
plume-specific averaged values. We believe that MODIS values are a
conservative estimation of plume aerosol optical depth (AOD) since MODIS algorithms rely on general
aerosol models and various atmospheric conditions within the look-up tables,
which do not reflect the highly absorbing nature of these smoke plumes.
Based on this study we conclude that the MODIS land algorithms are not yet
suited for retrieving aerosol properties for these types of smoke plumes due
to the strong absorbing properties of these aerosols. CALIPSO retrievals
rely heavily on the type of lidar solutions showing discrepancy between
constrained and unconstrained retrievals. Smoke plumes identified within a
larger aerosol layer were treated as unconstrained retrievals and resulted
in conservative AOD estimates. Conversely, smoke plumes surrounded by clear
air were identified as opaque aerosol layers and resulted in higher lidar
ratios and AOD values. Measured lidar ratios and particulate depolarization
ratios showed values similar to the upper ranges of biomass burning smoke.
Results agree with studies that utilized ground-based retrievals, in
particular for Ångström exponent (AE) and effective radius
(Reff) values. MODIS and CALIPSO retrieval algorithms disagree on AOD
ranges, for the most part, due to the extreme light-absorbing nature of
these types of aerosols. We believe that these types of studies are a strong
indicator for the need of improved aerosol models and retrieval algorithms.