Aerosol Characteristics During the Covid-19 Lockdown in China: Optical Properties, Vertical Distribution and Potential Source

2021 ◽  
Author(s):  
Yinbao Jin ◽  
Yingying Ma ◽  
Ming Zhang ◽  
Yiming Liu ◽  
Xiao Lu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Vertical Distribution ◽  
Potential Source

Vertical distribution and optical properties of aerosols observed over Japan during the Atmospheric Brown Clouds–East Asia Regional Experiment 2005

2007 ◽  
Vol 112 (D22) ◽  
Author(s):  
Tadahiro Hayasaka ◽  
Shinsuke Satake ◽  
Atsushi Shimizu ◽  
Nobuo Sugimoto ◽  
Ichiro Matsui ◽  
...  
Keyword(s):  
Optical Properties ◽  
Vertical Distribution ◽  
East Asia

Mysterious iron-nickel-zinc arctic spherules

1998 ◽  
Vol 35 (1) ◽  
pp. 23-29 ◽  
Author(s):  
Dennis A Darby
Keyword(s):  
Optical Properties ◽  
Arctic Ocean ◽  
Anthropogenic Source ◽  
Central Arctic Ocean ◽  
Devon Island ◽  
Nickel Zinc ◽  
Potential Source ◽  
Iron Nickel ◽  
Source Sample ◽  
Paleozoic Carbonates

An investigation into the sources of ice-rafted detritus in the central Arctic Ocean using microprobe analyses of detrital Fe oxide minerals discovered unique magnetic spherules in 20 of 144 potential source sample sites from the shelves and coastal areas around this ocean. The spherules occur only in samples from the Queen Elizabeth Islands, Canada. These grains are characterized by a 45-60 µm diameter, pitting throughout, and are occasionally found as multiple joint spherules. They have the optical properties of magnetite and, most remarkably, contain both ZnO and NiO in subequal amounts of up to 25%. The Ni suggests either an anthropogenic or meteoritic source. These spherules were probably ice-rafted into the central Arctic Ocean, where they are found in sediments of Holocene age and back to at least 780 ka, eliminating an anthropogenic source. Because Zn is too volatile to survive entry of a meteor through the earth's atmosphere, these spherules were probably formed during impact of an Fe-Ni meteor in an area of abundant Zn, perhaps the Zn rich Paleozoic carbonates of the Queen Elizabeth Islands. Examination of the ejecta and sediments filling the 22 Ma Haughton Astrobleme impact site on Devon Island, a carbonate terrain, revealed few magnetite spherules. None of these were pitted or contained Ni, but a few percent of ZnO were found in three spherules. Thus, the origin of these magnetite spherules remains unknown. The unique appearance and geochemistry of these spherules are useful in tracing Arctic Ocean ice-rafted detritus to its source.

scholarly journals Effect of sea‐ice melt on inherent optical properties and vertical distribution of solar radiant heating in Arctic surface waters

2015 ◽  
Vol 120 (10) ◽  
pp. 7028-7039 ◽  
Author(s):  
Mats A. Granskog ◽  
Alexey K. Pavlov ◽  
Sławomir Sagan ◽  
Piotr Kowalczuk ◽  
Anna Raczkowska ◽  
...  
Keyword(s):  
Optical Properties ◽  
Sea Ice ◽  
Vertical Distribution ◽  
Surface Waters ◽  
Radiant Heating ◽  
Ice Melt ◽  
Inherent Optical Properties ◽  
Arctic Surface

scholarly journals ESTIMATION OF OCEANIC PARTICULATE ORGANIC CARBON WITH MACHINE LEARNING

2020 ◽  
Vol V-2-2020 ◽  
pp. 949-956
Author(s):  
R. Sauzède ◽  
J. E. Johnson ◽  
H. Claustre ◽  
G. Camps-Valls ◽  
A. B. Ruescas
Keyword(s):  
Machine Learning ◽  
Optical Properties ◽  
Organic Carbon ◽  
Vertical Distribution ◽  
Particulate Organic Carbon ◽  
Ocean Color ◽  
Global Scale ◽  
Vertical Profiles ◽  
The Vertical Distribution ◽  
Satellite Ocean Color

Abstract. Understanding and quantifying ocean carbon sinks of the planet is of paramount relevance in the current scenario of global change. Particulate organic carbon (POC) is a key biogeochemical parameter that helps us characterize export processes of the ocean. Ocean color observations enable the estimation of bio-optical proxies of POC (i.e. particulate backscattering coefficient, bbp) in the surface layer of the ocean quasi-synoptically. In parallel, the Argo program distributes vertical profiles of the physical properties with a global coverage and a high spatio-temporal resolution. Merging satellite ocean color and Argo data using a neural networkbased method has already shown strong potential to infer the vertical distribution of bio-optical properties at global scale with high space-time resolution. This method is trained and validated using a database of concurrent vertical profiles of temperature, salinity, and bio-optical properties, i.e. bbp, collected by Biogeochemical-Argo (BGC-Argo) floats, matched up with satellite ocean color products. The present study aims at improving this method by 1) using a larger dataset from BGC-Argo network since 2016 for training, 2) using additional inputs such as altimetry data, which provide significant information on mesoscale processes impacting the vertical distribution of bbp, 3) improving the vertical resolution of estimation, and 4) examining the potential of alternative machine learning-based techniques. As a first attempt with the new data, we used some feature-specific preprocessing routines followed by a Multi-Output Random Forest algorithm on two regions with different ocean dynamics: North Atlantic and Subtropical Gyres. The statistics and the bbp profiles obtained from the validation floats show promising results and suggest this direction is worth investigating even further at global scale.

scholarly journals Vertical distribution of fish and krill beneath water of varying optical properties

1996 ◽  
Vol 136 ◽  
pp. 51-58 ◽  
Author(s):  
S Kaartvedt ◽  
W Melle ◽  
T Knutsen ◽  
HR Skjoldal
Keyword(s):  
Optical Properties ◽  
Vertical Distribution ◽  
Distribution Of Fish

scholarly journals Aircraft vertical profiles during summertime regional and Saharan dust scenarios over the north-western Mediterranean Basin: aerosol optical and physical properties

2020 ◽  
Author(s):  
Jesús Yus-Díez ◽  
Marina Ealo ◽  
Marco Pandolfi ◽  
Noemí Perez ◽  
Gloria Titos ◽  
...  
Keyword(s):  
Optical Properties ◽  
Vertical Distribution ◽  
Asymmetry Parameter ◽  
Mediterranean Basin ◽  
Western Mediterranean ◽  
Saharan Dust ◽  
Vertical Profiles ◽  
Measurement Campaign ◽  
Western Mediterranean Basin ◽  
Ne Spain

Abstract. Accurate measurements of the horizontal and vertical distribution of atmospheric aerosol particle optical properties are key for a better understanding of their impact on the climate. Here we present the results of a measurement campaign based on instrumented flights over NE Spain. We measured vertical profiles of size segregated atmospheric particulate matter (PM) mass concentrations and multi-wavelength scattering and absorption coefficients in the Western Mediterranean Basin (WMB). The campaign took place during typical summer conditions, characterized by the development of a vertical multi-layer structure, under both summer regional pollution episodes (REG) and Saharan dust events (SDE). REG patterns in the region form under high insolation and scarce precipitation in summer, favoring layering of highly-aged fine PM strata in the lower few km a.s.l. The REG scenario prevailed during the entire measurement campaign. Additionally, African dust outbreaks and plumes from North African wildfires influenced the study area. The vertical profiles of climate relevant intensive optical parameters such as single scattering albedo (SSA), asymmetry parameter (g), scattering, absorption and SSA Angstrom exponents (SAE, AAE, SSAAE), and PM mas scattering and absorption cross sections (MSC and MAE) were derived from the measurements. Moreover, we compared the aircraft measurements with those performed at two GAW/ACTRIS surface measurement stations located in NE Spain, namely: Montseny (MSY; regional background) and Montsec d'Ares (MSA; remote site). Airborne in-situ measurements and ceilometer ground-based remote measurements identified aerosol air masses at altitude up to more than 3.5 km a.s.l. The vertical profiles of the optical properties markedly changed according to the prevailing atmospheric scenarios. During SDE the SAE was low along the profiles, reaching values  2.0 and the asymmetry parameter g was rather low (0.5–0.6) due to the prevalence of fine PM which were characterized by an AAE close to 1.0 suggesting a fossil fuel combustion origin. During REG, some of the layers featured larger AAE (> 1.5), relatively low SSA at 525 nm ( 9 m2 g−1) and were associated to the influence of PM from wildfires. Overall, the SSA and MSC near the ground ranged around 0.85 and 3 m2 g−1, respectively and increased at higher altitudes, reaching values above 0.95 and up to 9 m2 g−1. The PM, MSC and MAE were on average larger during REG compared to SDE due to the larger scattering and absorption efficiency of fine PM compared with dust. The SSA and MSC had quite similar vertical profiles and often both increased with height indicating the progressive shift toward PM with larger scattering efficiency with altitude. This study contributes to our understanding of regional aerosol vertical distribution and optical properties in the WMB and the results will be useful for improving future climate projections and remote sensing/satellite retrieval algorithms.

Measurement of aerosol optical properties and their potential source origin in urban Beijing from 2013-2017

2019 ◽  
Vol 206 ◽  
pp. 293-302 ◽  
Author(s):  
Tiantian Wang ◽  
Zhuofei Du ◽  
Tianyi Tan ◽  
Nan Xu ◽  
Min Hu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Aerosol Optical Properties ◽  
Potential Source

scholarly journals Aerosol vertical distribution and optical properties over China from long-term satellite and ground-based remote sensing

2017 ◽  
Vol 17 (4) ◽  
pp. 2509-2523 ◽  
Author(s):  
Pengfei Tian ◽  
Xianjie Cao ◽  
Lei Zhang ◽  
Naixiu Sun ◽  
Lu Sun ◽  
...  
Keyword(s):  
Optical Properties ◽  
Vertical Distribution ◽  
North China Plain ◽  
Aerosol Extinction ◽  
The North ◽  
Range Transport ◽  
Seasonal And Spatial Variations ◽  
Ground Based Lidar ◽  
Lapse Rates

Abstract. The seasonal and spatial variations of vertical distribution and optical properties of aerosols over China are studied using long-term satellite observations from the Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP) and ground-based lidar observations and Aerosol Robotic Network (AERONET) data. The CALIOP products are validated using the ground-based lidar measurements at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL). The Taklamakan Desert and Tibetan Plateau regions exhibit the highest depolarization and color ratios because of the natural dust origin, whereas the North China Plain, Sichuan Basin and Yangtze River Delta show the lowest depolarization and color ratios because of aerosols from secondary formation of the anthropogenic origin. Certain regions, such as the North China Plain in spring and the Loess Plateau in winter, show intermediate depolarization and color ratios because of mixed dust and anthropogenic aerosols. In the Pearl River Delta region, the depolarization and color ratios are similar to but higher than those of the other polluted regions because of combined anthropogenic and marine aerosols. Long-range transport of dust in the middle and upper troposphere in spring is well captured by the CALIOP observations. The seasonal variations in the aerosol vertical distributions reveal efficient transport of aerosols from the atmospheric boundary layer to the free troposphere because of summertime convective mixing. The aerosol extinction lapse rates in autumn and winter are more positive than those in spring and summer, indicating trapped aerosols within the boundary layer because of stabler meteorological conditions. More than 80 % of the column aerosols are distributed within 1.5 km above the ground in winter, when the aerosol extinction lapse rate exhibits a maximum seasonal average in all study regions except for the Tibetan Plateau. The aerosol extinction lapse rates in the polluted regions are higher than those of the less polluted regions, indicating a stabilized atmosphere due to absorptive aerosols in the polluted regions. Our results reveal that the satellite and ground-based remote-sensing measurements provide the key information on the long-term seasonal and spatial variations in the aerosol vertical distribution and optical properties, regional aerosol types, long-range transport and atmospheric stability, which can be utilized to more precisely assess the direct and indirect aerosol effects on weather and climate.

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