scholarly journals An assessment of Biomass Burning Aerosol Optical Properties over the Mediterranean Basin based on Satellite Data

2019 ◽  
Author(s):  
IOANNIS MANTHOS ◽  
NIKOLAOS HATZIANASTASSIOU ◽  
ANGELIKI FOTIADI ◽  
ELIAS HOUSSOS ◽  
NIKOLAOS KOUTSIAS
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Satellite Data ◽  
Mediterranean Basin ◽  
Aerosol Optical Properties ◽  
Biomass Burning Aerosol ◽  
The Mediterranean ◽  
The Mediterranean Basin

scholarly journals Sensitivity of aerosol optical properties to the aerosol size distribution over central Europe and the Mediterranean Basin using the WRF-Chem v.3.9.1.1 coupled model

2020 ◽  
Vol 13 (12) ◽  
pp. 5897-5915
Author(s):  
Laura Palacios-Peña ◽  
Jerome D. Fast ◽  
Enrique Pravia-Sarabia ◽  
Pedro Jiménez-Guerrero
Keyword(s):  
Optical Properties ◽  
Standard Deviation ◽  
Size Distribution ◽  
Central Europe ◽  
Mediterranean Basin ◽  
Aerosol Size Distribution ◽  
Aerosol Optical Properties ◽  
Accumulation Mode ◽  
The Mediterranean ◽  
The Mediterranean Basin

Abstract. The size distribution of atmospheric aerosols plays a key role for understanding and quantifying the uncertainties related to aerosol–radiation and aerosol–cloud interactions. These interactions ultimately depend on the size distribution through optical properties (such as aerosol optical depth, AOD) or cloud microphysical properties. Hence, the main objective of this contribution is to disentangle the impact of the representation of aerosol size distribution on aerosol optical properties over central Europe, particularly over the Mediterranean Basin, during a summertime aerosol episode. To fulfill this objective, a sensitivity test has been conducted using the coupled chemistry–meteorology model WRF-Chem (Weather Research Forecast model coupled with Chemistry). The test modified the parameters defining a lognormal size distribution (geometric diameter and standard deviation) by 10 %, 20 %, and 50 %. Results reveal that the reduction in the standard deviation of the accumulation mode leads to the largest impacts on AOD due to a transfer of particles from the accumulation mode to the coarse mode. A reduction in the geometric diameter of the accumulation mode also has an influence on AOD representation since particles in this mode are assumed to be smaller. In addition, an increase in the geometric diameter of the coarse mode produces a redistribution through the total size distribution by relocating particles from the finer modes to the coarse.

scholarly journals Sensitivity of aerosol optical properties to the aerosol size distribution over central Europe and the Mediterranean Basin

2020 ◽  
Author(s):  
Laura Palacios-Peña ◽  
Jerome D. Fast ◽  
Enrique Pravia-Sarabia ◽  
Pedro Jiménez-Guerrero
Keyword(s):  
Optical Properties ◽  
Size Distribution ◽  
Central Europe ◽  
Mediterranean Basin ◽  
Aerosol Size Distribution ◽  
Aerosol Optical Properties ◽  
Accumulation Mode ◽  
Coarse Mode ◽  
The Mediterranean ◽  
The Mediterranean Basin

Abstract. Aerosol size distribution is, among others, a key property of atmospheric aerosols when trying to establish the uncertainties related to aerosol-radiation (ARI) and aerosol-clouds (ACI) interactions. These interactions ultimately depend on the size distribution through optical properties as aerosol optical depth (AOD) or cloud microphysical properties. Hence, the main objective of this work is to study the impact of the representation of aerosol size distribution on aerosol optical properties over Central Europe, and particularly over the Mediterranean Basin during a summertime aerosol episode. To fulfill this objective, a sensitivity test has been carried out using the WRF-Chem on-line model. The test consisted on modifying the parameters which define a log-normal size distribution (the geometric diameter, from now on DG, and the standard deviation, SG) by 10, 20 and 50 %. Results reveal that the reduction in the SG of the accumulation mode leads to the largest impacts in the AOD representation due to a transfer of particles from the accumulation mode to the coarse mode. A reduction in the DG of the accumulation mode has also an influence on AOD representation since particles in this mode are assumed to be smaller. In addition, an increase in the DG of the coarse mode produces a redistribution through the total size distribution by relocating particles from the finer modes to the coarse.

scholarly journals Aerosol direct radiative forcing during Sahara dust intrusions in the Central Mediterranean

2010 ◽  
Vol 10 (8) ◽  
pp. 20673-20727
Author(s):  
M. R. Perrone ◽  
A. Bergamo ◽  
V. Bellantone
Keyword(s):  
Optical Properties ◽  
Radiative Transfer ◽  
Spectral Range ◽  
Mediterranean Basin ◽  
Transfer Model ◽  
Clear Sky ◽  
Fine Mode ◽  
The Mediterranean ◽  
The Mediterranean Basin ◽  
Sahara Dust

Abstract. The clear-sky, instantaneous Direct Radiative Effect (DRE) by all and anthropogenic particles is calculated during Sahara dust intrusions in the Mediterranean basin, to evaluate the role of anthropogenic particle's radiative effects and to obtain a better estimate of the DRE by desert dust. The clear-sky aerosol DRE is calculated by a two stream radiative transfer model in the solar (0.3–4 μm) and infrared (4–200 μm) spectral range, at the top of the atmosphere (ToA) and at the Earth's surface (sfc). Aerosol optical properties by AERONET sun-sky photometer measurements and aerosol vertical profiles by EARLINET lidar measurements, both performed at Lecce (40.33° N, 18.10° E) during Sahara dust intrusions occurred from 2003 to 2006 year, are used to perform radiative transfer simulations. Instantaneous values at 0.44 μm of the real (n) and imaginary (k) refractive index and of the of aerosol optical depth (AOD) vary within the 1.33–1.55, 0.0037–0.014, and 0.2–0.7 range, respectively during the analyzed dust outbreaks. Fine mode particles contribute from 34% to 85% to the AOD by all particles. The complex atmospheric chemistry of the Mediterranean basin that is also influenced by regional and long-range transported emissions from continental Europe and the dependence of dust optical properties on soil properties of source regions and transport pathways, are responsible for the high variability of n, k, and AOD values and of the fine mode particle contribution. Instantaneous all-wave (solar+infrared) DREs that are negative as a consequence of the cooling effect by aerosol particles, span the – (32–10) Wm−2 and the – (44–20) Wm−2 range at the ToA and surface, respectively. The instantaneous all-wave DRE by anthropogenic particles that is negative, varies within – (13–7) Wm−2 and – (18–11) Wm−2 at the ToA and surface, respectively. It represents from 41% up to 89% and from 32% up to 67% of the all-wave DRE by all particles at the ToA and surface, respectively during the analysed dust outbreaks. A linear relationship to calculate the DRE by natural particles in the solar and infrared spectral range is provided.

scholarly journals Intercomparison of biomass burning aerosol optical properties from in situ and remote-sensing instruments in ORACLES-2016

2019 ◽  
Vol 19 (14) ◽  
pp. 9181-9208 ◽  
Author(s):  
Kristina Pistone ◽  
Jens Redemann ◽  
Sarah Doherty ◽  
Paquita Zuidema ◽  
Sharon Burton ◽  
...  
Keyword(s):  
Optical Properties ◽  
Case Studies ◽  
Biomass Burning ◽  
Radiative Forcing ◽  
Measurement Techniques ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Aerosol Optical Properties ◽  
Biomass Burning Aerosol

Abstract. The total effect of aerosols, both directly and on cloud properties, remains the biggest source of uncertainty in anthropogenic radiative forcing on the climate. Correct characterization of intensive aerosol optical properties, particularly in conditions where absorbing aerosol is present, is a crucial factor in quantifying these effects. The southeast Atlantic Ocean (SEA), with seasonal biomass burning smoke plumes overlying and mixing with a persistent stratocumulus cloud deck, offers an excellent natural laboratory to make the observations necessary to understand the complexities of aerosol–cloud–radiation interactions. The first field deployment of the NASA ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) campaign was conducted in September of 2016 out of Walvis Bay, Namibia. Data collected during ORACLES-2016 are used to derive aerosol properties from an unprecedented number of simultaneous measurement techniques over this region. Here, we present results from six of the eight independent instruments or instrument combinations, all applied to measure or retrieve aerosol absorption and single-scattering albedo. Most but not all of the biomass burning aerosol was located in the free troposphere, in relative humidities typically ranging up to 60 %. We present the single-scattering albedo (SSA), absorbing and total aerosol optical depth (AAOD and AOD), and absorption, scattering, and extinction Ångström exponents (AAE, SAE, and EAE, respectively) for specific case studies looking at near-coincident and near-colocated measurements from multiple instruments, and SSAs for the broader campaign average over the month-long deployment. For the case studies, we find that SSA agrees within the measurement uncertainties between multiple instruments, though, over all cases, there is no strong correlation between values reported by one instrument and another. We also find that agreement between the instruments is more robust at higher aerosol loading (AOD400>0.4). The campaign-wide average and range shows differences in the values measured by each instrument. We find the ORACLES-2016 campaign-average SSA at 500 nm (SSA500) to be between 0.85 and 0.88, depending on the instrument considered (4STAR, AirMSPI, or in situ measurements), with the interquartile ranges for all instruments between 0.83 and 0.89. This is consistent with previous September values reported over the region (between 0.84 and 0.90 for SSA at 550nm). The results suggest that the differences observed in the campaign-average values may be dominated by instrument-specific spatial sampling differences and the natural physical variability in aerosol conditions over the SEA, rather than fundamental methodological differences.

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