scholarly journals Observations of resonant scattering in the thermosphere and upper mesosphere in the winter season of 2021

2021 ◽  
Vol 254 ◽  
pp. 01005
Author(s):  
Vasily Bychkov ◽  
Ilia Seredkin ◽  
Alexei Dmitriev
Keyword(s):  
Light Scattering ◽  
Charged Particles ◽  
Winter Season ◽  
Resonant Scattering ◽  
Lidar Data ◽  
Ionospheric Parameter ◽  
Atomic Nitrogen ◽  
Mesopause Region ◽  
Station Data

An analysis of the Kamchatka lidar station data obtained in January-February 2021 is presented. Pronounced light scattering layers at altitudes of 300 km have been detected. Layers at these heights appear during precipitation of electrons with energies of about 300 eV. Analysis of the lidar data showed that increased light scattering was observed at the heights of the mesosphere, accompanied by an increase in the ionospheric parameter fmin. It was concluded that the observed aerosol formations in the mesopause region could be caused by precipitation of charged particles with energies of ∼ 500 keV. Aerosol formations in the area of 60-75 km should be recognized as imaginary. This is a manifestation of resonant scattering by excited ions of atomic nitrogen

Aerosol chemical composition and light scattering during a winter season in Beijing

2015 ◽  
Vol 110 ◽  
pp. 36-44 ◽  
Author(s):  
Jun Tao ◽  
Leiming Zhang ◽  
Jian Gao ◽  
Han Wang ◽  
Faihe Chai ◽  
...  
Keyword(s):  
Light Scattering ◽  
Chemical Composition ◽  
Winter Season ◽  
Aerosol Chemical Composition

scholarly journals Synergy of lidar and passive remote sensor data for retrieving profiles of microphysical properties of non-spherical particles

2018 ◽  
Vol 176 ◽  
pp. 08001
Author(s):  
Alexei Kolgotin ◽  
Detlef Müller ◽  
Eduard Chemyakin ◽  
Anton Romanov
Keyword(s):  
Light Scattering ◽  
Phase Function ◽  
Sensor Data ◽  
Spherical Particles ◽  
Lidar Data ◽  
Scattering Model ◽  
Remote Sensors ◽  
Microphysical Properties ◽  
Remote Sensor

In this study we explore how the combination of 3 backscatter and 2 extinction lidar data with data that can be collected with ground-based and space-borne passive remote sensors, e.g. phase function coefficients which can be derived at various measurement wavelengths and scattering angles can result in improved profiles of particle microphysical properties. The algorithm is based on a light-scattering model that uses a mixture of spheres and randomly oriented spheroids.

scholarly journals Analysis of 24 years of mesopause region OH rotational temperature observations at Davis, Antarctica – Part 1: long-term trends

2020 ◽  
Vol 20 (11) ◽  
pp. 6379-6394 ◽  
Author(s):  
W. John R. French ◽  
Frank J. Mulligan ◽  
Andrew R. Klekociuk
Keyword(s):  
Solar Cycle ◽  
Rotational Temperature ◽  
Winter Season ◽  
Pressure Level ◽  
Recent Analysis ◽  
Research Station ◽  
Mesopause Region ◽  
Term Trend ◽  
Long Term Trend

Abstract. The long-term trend, solar cycle response, and residual variability in 24 years of hydroxyl nightglow rotational temperatures above Davis research station, Antarctica (68∘ S, 78∘ E) are reported. Hydroxyl rotational temperatures are a layer-weighted proxy for kinetic temperatures near 87 km altitude and have been used for many decades to monitor trends in the mesopause region in response to increasing greenhouse gas emissions. Routine observations of the OH(6-2) band P-branch emission lines using a scanning spectrometer at Davis station have been made continuously over each winter season since 1995. Significant outcomes of this most recent analysis update are the following: (a) a record-low winter-average temperature of 198.3 K is obtained for 2018 (1.7 K below previous low in 2009); (b) a long-term cooling trend of -1.2±0.51 K per decade persists, coupled with a solar cycle response of 4.3±1.02 K per 100 solar flux units; and (c) we find evidence in the residual winter mean temperatures of an oscillation on a quasi-quadrennial (QQO) timescale which is investigated in detail in Part 2 of this work. Our observations and trend analyses are compared with satellite measurements from Aura/MLS version v4.2 level-2 data over the last 14 years, and we find close agreement (a best fit to temperature anomalies) with the 0.00464 hPa pressure level values. The solar cycle response (3.4±2.3 K per 100 sfu), long-term trend (-1.3±1.2 K per decade), and underlying QQO residuals in Aura/MLS are consistent with the Davis observations. Consequently, we extend the Aura/MLS trend analysis to provide a global view of solar response and long-term trend for Southern and Northern Hemisphere winter seasons at the 0.00464 hPa pressure level to compare with other observers and models.

scholarly journals Reducing uncertainties associated with filter-based optical measurements of soot aerosol particles with chemical information

2010 ◽  
Vol 3 (2) ◽  
pp. 1197-1227 ◽  
Author(s):  
J. E. Engström ◽  
C. Leck
Keyword(s):  
Light Scattering ◽  
Indian Ocean ◽  
Radiative Forcing ◽  
Light Transmission ◽  
Aerosol Particles ◽  
Winter Season ◽  
Optical Measurements ◽  
Chemical Information ◽  
Polycarbonate Membrane ◽  
South Indian

Abstract. Of the many identified and potential effects of atmospheric aerosol particles on climate, those of soot particles are the most uncertain, in that analytical techniques concerning soot are far from satisfactory. One concern when applying filter-based optical measurements of soot is that they suffer from systematic errors due to the light scattering of non-absorbing particles co-deposited on the filter, such as inorganic salts and mineral dust. In addition to an optical correction of the non-absorbing material this study provides a protocol for correction of light scattering based on the chemical quantification of the material, which is a novelty. A newly designed Particle Soot Absorption Photometer was constructed to measure light transmission on particle accumulating filters, which includes an additional sensor recording backscattered light. The choice of polycarbonate membrane filters avoided high chemical blank values and reduced errors associated with length of the light path through the filter. Two protocols for corrections were applied to aerosol samples collected at the Maldives Climate Observatory Hanimaadhoo during episodes with either continentally influenced air from the Indian/Arabian subcontinents (winter season) or pristine air from the Southern Indian Ocean (summer monsoon). The two ways of correction (optical and chemical) lowered the particle light absorption of soot by 63 to 61%, respectively, for data from the Arabian Sea sourced group, resulting in median soot absorption coefficients of 4.2 and 3.5 Mm-1. Corresponding values for the South Indian Ocean data were 69 and 97% (0.38 and 0.02 Mm-1). A comparison with other studies in the area indicated an overestimation of their soot levels, by up to two orders of magnitude. This raises the necessity for chemical correction protocols on optical filter-based determinations of soot, before even the sign on the radiative forcing based on their effects can be assessed.

scholarly journals Scattering on excited atmospheric components as a cause of the increase of lidar signal in the upper and middle atmosphere

2020 ◽  
Vol 196 ◽  
pp. 01008
Author(s):  
Vasily Bychkov ◽  
Ilya Seredkin
Keyword(s):  
Laser Pulse ◽  
Middle Atmosphere ◽  
Resonant Scattering ◽  
Lidar Data ◽  
Lidar Signal ◽  
Scattering Signal

The lidar data of the resonant scattering in the upper and middle Kamchatka atmosphere are analyzed. It is shown that the increase of the scattering signal at altitudes of 350-450 km at 561 nm may be due to the scattering of the maximum of layer F2 excited by precipitated electrons on ions. Large variations in the signal at these altitudes are caused by spatial plasma inhomogeneities in the ionosphere, as confirmed by the ionosonde data. The analysis of the interaction of a laser pulse with excited ions in the stratosphere is refined, and the effect of collisions on the lifetime is taken into account. It is shown that for the used lidar in the middle atmosphere for altitudes above 10 km, the conditions of guaranteed interaction with the radiation of each ion born in the strobe are satisfied.

scholarly journals Reducing uncertainties associated with filter-based optical measurements of light absorbing carbon particles with chemical information

2011 ◽  
Vol 4 (8) ◽  
pp. 1553-1566 ◽  
Author(s):  
J. E. Engström ◽  
C. Leck
Keyword(s):  
Light Scattering ◽  
Indian Ocean ◽  
Radiative Forcing ◽  
Light Transmission ◽  
Optical Filter ◽  
Winter Season ◽  
Optical Measurements ◽  
Chemical Information ◽  
Polycarbonate Membrane ◽  
South Indian

Abstract. The presented filter-based optical method for determination of soot (light absorbing carbon or Black Carbon, BC) can be implemented in the field under primitive conditions and at low cost. This enables researchers with small economical means to perform monitoring at remote locations, especially in the Asia where it is much needed. One concern when applying filter-based optical measurements of BC is that they suffer from systematic errors due to the light scattering of non-absorbing particles co-deposited on the filter, such as inorganic salts and mineral dust. In addition to an optical correction of the non-absorbing material this study provides a protocol for correction of light scattering based on the chemical quantification of the material, which is a novelty. A newly designed photometer was implemented to measure light transmission on particle accumulating filters, which includes an additional sensor recording backscattered light. The choice of polycarbonate membrane filters avoided high chemical blank values and reduced errors associated with length of the light path through the filter. Two protocols for corrections were applied to aerosol samples collected at the Maldives Climate Observatory Hanimaadhoo during episodes with either continentally influenced air from the Indian/Arabian subcontinents (winter season) or pristine air from the Southern Indian Ocean (summer monsoon). The two ways of correction (optical and chemical) lowered the particle light absorption of BC by 63 to 61 %, respectively, for data from the Arabian Sea sourced group, resulting in median BC absorption coefficients of 4.2 and 3.5 Mm−1. Corresponding values for the South Indian Ocean data were 69 and 97 % (0.38 and 0.02 Mm−1). A comparison with other studies in the area indicated an overestimation of their BC levels, by up to two orders of magnitude. This raises the necessity for chemical correction protocols on optical filter-based determinations of BC, before even the sign on the radiative forcing based on their effects can be assessed.

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