scholarly journals Morphological features and mixing states of soot-containing particles in the marine boundary layer over the Indian and Southern Oceans

2018 ◽  
Author(s):  
Sayako Ueda ◽  
Kazuo Osada ◽  
Keiichiro Hara ◽  
Masanori Yabuki ◽  
Fuminori Hashihama ◽  
...  
Keyword(s):  
South Africa ◽  
Boundary Layer ◽  
Indian Ocean ◽  
Marine Boundary Layer ◽  
Aerosol Particles ◽  
Morphological Features ◽  
Absorption Coefficients ◽  
Climatic Effects ◽  
Mixing States ◽  
Carbon Aerosols

Abstract. Mixing states of soot-containing aerosol particles are important information for the simulation of climatic effects of black carbon aerosols in the atmosphere. To elucidate the mixing states and morphological features of soot-containing particles in remote ocean areas, we conducted onboard observations over the southern Indian Ocean and the Southern Ocean during the TR/V Umitaka-maru UM-08-09 cruise, which started from Benoa, Indonesia on 1 December 2008 via Cape Town, South Africa and which terminated in Fremantle, Australia on 6 February 2009. The light absorption coefficients of size-segregated particles (

scholarly journals Cloud Processing of Aerosol Particles in Marine Stratocumulus Clouds

Atmosphere ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 520 ◽  
Author(s):  
Andrea I. Flossmann ◽  
Wolfram Wobrock
Keyword(s):  
Boundary Layer ◽  
Marine Boundary Layer ◽  
Numerical Study ◽  
Spatial Scales ◽  
Aerosol Particles ◽  
Cloud Microphysics ◽  
Marine Stratocumulus ◽  
Boundary Layer Clouds ◽  
Cloud Processing ◽  
Stratocumulus Clouds

Cloud processing of aerosol particles is an important process and is, for example, thought to be responsible for the so-called “Hoppel-minimum” in the marine aerosol particle distribution or contribute to the cell organization of marine boundary layer clouds. A numerical study of the temporal and spatial scales of the processing of aerosol particles by typical marine stratocumulus clouds is presented. The dynamical framework is inspired by observations during the VOCALS (Variability of the American Monsoon System Ocean-Cloud-Atmosphere-Land Study) Regional Experiment in the Southeast Pacific. The 3-D mesoscale model version of DESCAM (Detailed Scavenging Model) follows cloud microphysics of the stratocumulus deck in a bin-resolved manner and has been extended to keep track of cloud-processed particles in addition to non-processed aerosol particles in the air and inside the cloud drops. The simulation follows the evolution of the processing of aerosol particles by the cloud. It is found that within one hour almost all boundary layer aerosol particles have passed through at least one cloud cycle. However, as the in-cloud residence times of the particles in the considered case are only on the order of minutes, the aerosol particles remain essentially unchanged. Our findings suggest that in order to produce noticeable microphysical and dynamical effects in the marine boundary layer clouds, cloud processing needs to continue for extended periods of time, exceeding largely the time period considered in the present study. A second model study is dedicated to the interaction of ship track particles with marine boundary layer clouds. The model simulates quite satisfactorily the incorporation of the ship plume particles into the cloud. The observed time and spatial scales and a possible Twomey effect were reproduced.

scholarly journals Volatile halocarbon measurements in the marine boundary layer at Cape Point, South Africa

2019 ◽  
Vol 214 ◽  
pp. 116833
Author(s):  
Brett Kuyper ◽  
Timothy Lesch ◽  
Casper Labuschagne ◽  
Damien Martin ◽  
Dickon Young ◽  
...  
Keyword(s):  
South Africa ◽  
Boundary Layer ◽  
Marine Boundary Layer ◽  
Volatile Halocarbon

Structure of the marine boundary layer over north western Indian Ocean during 1983 summer monsoon

1990 ◽  
Vol 52 (1-2) ◽  
pp. 177-191
Author(s):  
M. R. Ramesh Kumar ◽  
Y. Sadhuram ◽  
G. S. Michael ◽  
L. V. Gangadhara Rao
Keyword(s):  
Boundary Layer ◽  
Indian Ocean ◽  
Summer Monsoon ◽  
Marine Boundary Layer ◽  
Western Indian Ocean ◽  
North Western

scholarly journals Modelling the impacts of iodine chemistry on the northern Indian Ocean marine boundary layer

2021 ◽  
Vol 21 (11) ◽  
pp. 8437-8454
Author(s):  
Anoop S. Mahajan ◽  
Qinyi Li ◽  
Swaleha Inamdar ◽  
Kirpa Ram ◽  
Alba Badia ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Chemical Composition ◽  
Indian Ocean ◽  
Marine Boundary Layer ◽  
Indian Subcontinent ◽  
Winter Period ◽  
Monsoon Period ◽  
Mean Values ◽  
Iodine Chemistry ◽  
Inorganic Iodine

Abstract. Recent observations have shown the ubiquitous presence of iodine oxide (IO) in the Indian Ocean marine boundary layer (MBL). In this study, we use the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem version 3.7.1), including halogen (Br, Cl, and I) sources and chemistry, to quantify the impacts of the observed levels of iodine on the chemical composition of the MBL. The model results show that emissions of inorganic iodine species resulting from the deposition of ozone (O3) on the sea surface are needed to reproduce the observed levels of IO, although the current parameterizations overestimate the atmospheric concentrations. After reducing the inorganic emissions by 40 %, a reasonable match with cruise-based observations is found, with the model predicting values between 0.1 and 1.2 pptv across the model domain MBL. A strong seasonal variation is also observed, with lower iodine concentrations predicted during the monsoon period, when clean oceanic air advects towards the Indian subcontinent, and higher iodine concentrations predicted during the winter period, when polluted air from the Indian subcontinent increases the ozone concentrations in the remote MBL. The results show that significant changes are caused by the inclusion of iodine chemistry, with iodine-catalysed reactions leading to regional changes of up to 25 % in O3, 50 % in nitrogen oxides (NO and NO2), 15 % in hydroxyl radicals (OH), 25 % in hydroperoxyl radicals (HO2), and up to a 50 % change in the nitrate radical (NO3), with lower mean values across the domain. Most of the large relative changes are observed in the open-ocean MBL, although iodine chemistry also affects the chemical composition in the coastal environment and over the Indian subcontinent. These results show the importance of including iodine chemistry in modelling the atmosphere in this region.

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