A numeric estimate of the sensitivity of the land-based LIDAR echo signal to statistical variations of the aerosol scattering coefficient in a cloudless atmosphere

2016 ◽  
Author(s):  
B. A. Kargin ◽  
Y. G. Kablukova
Keyword(s):  
Scattering Coefficient ◽  
Echo Signal ◽  
Aerosol Scattering ◽  
Statistical Variations ◽  
Cloudless Atmosphere

Near Field Electromagnetic Scattering Model Studying for Coarse Sea Surface

2013 ◽  
Vol 756-759 ◽  
pp. 4586-4590
Author(s):  
Jun Gu ◽  
Kun Cai ◽  
Zi Chang Liang
Keyword(s):  
Electromagnetic Scattering ◽  
Near Field ◽  
Horn Antenna ◽  
Measured Data ◽  
Sea Surface ◽  
Scattering Coefficient ◽  
Distributed Model ◽  
Echo Signal ◽  
Scattering Model ◽  
Rough Sea

The simulated PM-spectrum fractal sea surfaces and the 3-D near-field distributed model of horn antenna are built, the near-field formulas of KA method are deduced. The near-field scattering coefficient and the Doppler echo signal of rough sea surfaces are calculated, the agreement with measured data proved the correctness and validity of the near-field scattering model.

scholarly journals Tropospheric aerosol scattering and absorption over Central Europe: a closure study for the dry particle state

2013 ◽  
Vol 13 (10) ◽  
pp. 27811-27854 ◽  
Author(s):  
N. Ma ◽  
W. Birmili ◽  
T. Müller ◽  
T. Tuch ◽  
Y. F. Cheng ◽  
...  
Keyword(s):  
Optical Properties ◽  
Direct Measurement ◽  
Radiative Forcing ◽  
Control Measure ◽  
Atmospheric Stability ◽  
Scattering Coefficient ◽  
Particle State ◽  
Air Mass ◽  
Aerosol Scattering ◽  
Tropospheric Aerosol

Abstract. This work analyses optical properties of the dry tropospheric aerosol measured at the regional GAW observation site Melpitz in East Germany. For a continuous observation period between 2007 and 2010, we provide representative values of the dry-state scattering coefficient, the hemispheric backscattering coefficient, the absorption coefficient, single scattering albedo, and the Ångström exponent. Besides the direct measurement, the aerosol scattering coefficient was alternatively computed from experimental particle number size distributions using a Mie code. Within pre-defined limits, a closure could be achieved with the direct measurement. The achievement of closure implies that such calculations can be used as a high-level quality control measure for data sets involving multiple instrumentation. All dry optical properties showed significant annual variations, which were attributed to corresponding variations in the regional emission fluxes, the intensity of secondary particle formation, and the mixed layer height. Air mass classification showed that atmospheric stability is a major factor influencing the dry aerosol properties at the GAW station. In the cold season, temperature inversions limit the volume available for atmospheric mixing, so that the aerosol optical properties near the ground proved quite sensitive to the geographical origin of the air mass. In the warm season, when the atmosphere is usually well-mixed during day-time, considerably less variability was observed for the optical properties between different air masses. This work provides, on the basis of quality-checked in-situ measurements, a first step towards a climatological assessment of direct aerosol radiative forcing in the region under study.

scholarly journals New correction method for the scattering coefficient measurements of a three-wavelength nephelometer

2021 ◽  
Vol 14 (7) ◽  
pp. 4879-4891
Author(s):  
Jie Qiu ◽  
Wangshu Tan ◽  
Gang Zhao ◽  
Yingli Yu ◽  
Chunsheng Zhao
Keyword(s):  
Relative Humidity ◽  
Radiative Forcing ◽  
Correction Method ◽  
High Accuracy ◽  
Scattering Coefficient ◽  
Observation Data ◽  
Machine Learning Model ◽  
Aerosol Scattering ◽  
Direct Radiative Forcing ◽  
Essential Parameter

Abstract. The aerosol scattering coefficient is an essential parameter for estimating aerosol direct radiative forcing and can be measured by nephelometers. Nephelometers are problematic due to small errors of nonideal Lambetian light source and angle truncation. Hence, the observed raw scattering coefficient data need to be corrected. In this study, based on the random forest machine learning model and taking Aurora 3000 as an example, we have proposed a new method to correct the scattering coefficient measurements of a three-wavelength nephelometer under different relative humidity conditions. The result shows that the empirical corrected values match Mie-calculation values very well at all three wavelengths and under all of the measured relative humidity conditions, with more than 85 % of the corrected values having less than 2 % error. The correction method obtains a scattering coefficient with high accuracy and there is no need for additional observation data.

scholarly journals A case study of dust aerosol radiative properties over Lanzhou, China

2010 ◽  
Vol 10 (2) ◽  
pp. 2889-2914 ◽  
Author(s):  
L. Zhang ◽  
X. Cao ◽  
J. Bao ◽  
B. Zhou ◽  
J. Huang ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Extinction Coefficient ◽  
Dust Storm ◽  
Dust Aerosol ◽  
Pm10 Concentration ◽  
Radiative Properties ◽  
Scattering Coefficient ◽  
Aerosol Extinction ◽  
Aerosol Scattering ◽  
Aerosol Extinction Coefficient

Abstract. The vertical distribution of dust aerosol and its radiative properties are analysed using the data measured by the micropulse lidar, profiling microwave radiometer, sunphotometer, particulate monitor, and nephelometer at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) during a dust storm from 27 March to 29 March 2007. The analysis shows that the dust aerosol mainly exists below 2 km in height, and the dust aerosol extinction coefficient decreases with height. The temporal evolution of aerosol optical depth (AOD) during the dust storm is characterized by a sub-maximum at 22:00 (Beijing Time) on 27 March and a maximum at 12:00 on 28 March. The AOD derived by lidar is compared with that obtained by sunphotometer, and shows a good consistency. The PM10 concentration and aerosol scattering coefficient share identical variation trends, and their maximums both appear at 22:00 on 27 March. The aerosol extinction coefficient and relative humidity have the same trends and their maximums appear at identical heights, showing a correlation between extinction coefficient and relative humidity known as aerosol hygroscopicity. Nevertheless, the correlation between aerosol extinction coefficient and temperature cannot be obviously seen. The aerosol extinction coefficient, scattering coefficient, and PM10 concentration present good linear correlations. The correlation coefficients of the aerosol scattering coefficient and PM10 concentration, of aerosol extinction coefficient and PM10 concentration, and of aerosol extinction and scattering coefficient are respectively 0.98, 0.94, and 0.96.

Influence of humidity on the aerosol scattering coefficient and its effect on the upwelling radiance during ACE-2

Tellus B ◽  
2000 ◽  
Vol 52 (2) ◽  
pp. 546-567 ◽  
Author(s):  
S. Gassó ◽  
D. A. Hegg ◽  
D. S. Covert ◽  
D. Collins ◽  
K. J. Noone ◽  
...  
Keyword(s):  
Scattering Coefficient ◽  
Aerosol Scattering

scholarly journals Development of a cavity enhanced aerosol albedometer

2014 ◽  
Vol 7 (3) ◽  
pp. 2981-3019
Author(s):  
W. Zhao ◽  
X. Xu ◽  
M. Dong ◽  
W. Chen ◽  
X. Gu ◽  
...  
Keyword(s):  
Single Channel ◽  
Broad Band ◽  
Single Scattering ◽  
Polystyrene Latex ◽  
Scattering Coefficient ◽  
Integrating Sphere ◽  
Instrumental Performance ◽  
Optical Extinction ◽  
Extinction Coefficients ◽  
Aerosol Scattering

Abstract. We report on the development of a cavity enhanced aerosol single scattering albedometer incorporating incoherent broad-band cavity-enhanced spectroscopy (IBBCEAS) approach and an integrating sphere (IS) for simultaneous in situ measurements of aerosol scattering and extinction coefficients in the exact same sample volume. The cavity enhanced albedometer employed a blue light-emitting diode (LED) based IBBCEAS approach for the measurement of wavelength-resolved aerosol optical extinction over the spectral range of 445–480 nm. An integrating sphere nephelometer coupled to the IBBCEAS setup was used for the measurement of aerosol scattering. The scattering signal was measured with a single channel photomultiplier tube (PMT), providing an integrated value over a narrow bandwidth (FWHM ~ 9 nm) in the spectral region of 465–474 nm. A scattering coefficient at a wavelength of 470 nm was deduced as an averaged scattering value and used for data analysis and instrumental performance comparison. Performance evaluation of the albedometer was carried out using laboratory-generated particles and ambient aerosol. The scattering and extinction measurements of monodisperse polystyrene latex (PSL) spheres generated in laboratory proved excellent correlation between two channels of the albedometer. The retrieved refractive index (RI) from the measured scattering and extinction efficiencies agreed well with the values reported in previously published papers. Aerosol light scattering and extinction coefficients, single scattering albedo (SSA) and NO2 concentrations in an ambient sample were directly and simultaneously measured using the developed albedometer. The developed instrument was validated via an intercomparison of the measured aerosol scattering coefficient and NO2 trace concentration against a TSI 3563 integrating nephelometer and a chemiluminescence detector, respectively.

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