Relative Humidity Dependence of Aerosol Optical Properties and Direct Radiative Forcing in the Surface Boundary Layer of Southeastern China

2007 ◽  
pp. 489-493
Author(s):  
Y. F. Cheng ◽  
Alfred Wiedensohler ◽  
H. Eichler ◽  
Y. H. Zhang ◽  
W. Birmili ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Optical Properties ◽  
Relative Humidity ◽  
Radiative Forcing ◽  
Surface Boundary ◽  
Aerosol Optical Properties ◽  
Southeastern China ◽  
Surface Boundary Layer ◽  
Direct Radiative Forcing ◽  
Humidity Dependence

scholarly journals A complete parameterisation of the relative humidity and wavelength dependence of the refractive index of hygroscopic inorganic aerosol particles

2017 ◽  
Vol 17 (16) ◽  
pp. 9837-9851 ◽  
Author(s):  
Michael I. Cotterell ◽  
Rose E. Willoughby ◽  
Bryan R. Bzdek ◽  
Andrew J. Orr-Ewing ◽  
Jonathan P. Reid
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Relative Humidity ◽  
Radiative Forcing ◽  
Aerosol Particles ◽  
Measurement Techniques ◽  
Comprehensive Treatment ◽  
Aerosol Optical Properties ◽  
Cavity Ring Down Spectroscopy ◽  
Cavity Ring Down

Abstract. Calculations of aerosol radiative forcing require knowledge of wavelength-dependent aerosol optical properties, such as single-scattering albedo. These aerosol optical properties can be calculated using Mie theory from knowledge of the key microphysical properties of particle size and refractive index, assuming that atmospheric particles are well-approximated to be spherical and homogeneous. We provide refractive index determinations for aqueous aerosol particles containing the key atmospherically relevant inorganic solutes of NaCl, NaNO3, (NH4)2SO4, NH4HSO4 and Na2SO4, reporting the refractive index variation with both wavelength (400–650 nm) and relative humidity (from 100 % to the efflorescence value of the salt). The accurate and precise retrieval of refractive index is performed using single-particle cavity ring-down spectroscopy. This approach involves probing a single aerosol particle confined in a Bessel laser beam optical trap through a combination of extinction measurements using cavity ring-down spectroscopy and elastic light-scattering measurements. Further, we assess the accuracy of these refractive index measurements, comparing our data with previously reported data sets from different measurement techniques but at a single wavelength. Finally, we provide a Cauchy dispersion model that parameterises refractive index measurements in terms of both wavelength and relative humidity. Our parameterisations should provide useful information to researchers requiring an accurate and comprehensive treatment of the wavelength and relative humidity dependence of refractive index for the inorganic component of atmospheric aerosol.

scholarly journals One year measurements of aerosol optical properties over an urban coastal site: Effect on local direct radiative forcing

2008 ◽  
Vol 90 (2-4) ◽  
pp. 195-202 ◽  
Author(s):  
Auromeet Saha ◽  
Marc Mallet ◽  
Jean Claude Roger ◽  
Philippe Dubuisson ◽  
Jacques Piazzola ◽  
...  
Keyword(s):  
Optical Properties ◽  
Radiative Forcing ◽  
Site Effect ◽  
Aerosol Optical Properties ◽  
Coastal Site ◽  
Direct Radiative Forcing ◽  
One Year

scholarly journals A Complete Parameterization of the Relative Humidity and Wavelength Dependence of the Refractive Index of Hygroscopic Inorganic Aerosol Particles

2017 ◽  
Author(s):  
Michael I. Cotterell ◽  
Rose E. Willoughby ◽  
Bryan R. Bzdek ◽  
Andrew J. Orr-Ewing ◽  
Jonathan P. Reid
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Relative Humidity ◽  
Radiative Forcing ◽  
Aerosol Particles ◽  
Measurement Techniques ◽  
Comprehensive Treatment ◽  
Aerosol Optical Properties ◽  
Cavity Ring Down Spectroscopy ◽  
Cavity Ring Down

Abstract. Calculations of aerosol radiative forcing require knowledge of wavelength-dependent aerosol optical properties, such as single scattering albedo. These aerosol optical properties can be calculated using Mie theory from knowledge of the key microphysical properties of particle size and refractive index, assuming that atmospheric particles are well-approximated to be spherical and homogeneous. We provide refractive index determinations for aqueous aerosol particles containing the key atmospherically relevant inorganic solutes of NaCl, NaNO3, (NH4)2SO4, NH4HSO4 and Na2SO4, reporting the refractive index variation with both wavelength (400–650 nm) and relative humidity (from 100 % to the efflorescence value of the salt). The accurate and precise retrieval of refractive index is performed using single particle cavity ring-down spectroscopy. This approach involves probing a single aerosol particle confined in a Bessel laser beam optical trap through a combination of extinction measurements by cavity ring-down spectroscopy and elastic light scattering measurements. Further, we assess the accuracy of these refractive index measurements, comparing our data with previously reported data sets from different measurement techniques but at a single wavelength. Finally, we provide a Cauchy dispersion model that parameterizes refractive index measurements in terms of both wavelength and relative humidity. Our parameterizations should provide useful information to researchers requiring an accurate and comprehensive treatment of the wavelength and relative humidity dependence of the inorganic component of atmospheric aerosol.

scholarly journals Sea spray aerosol as a unique source of ice nucleating particles

2015 ◽  
Vol 113 (21) ◽  
pp. 5797-5803 ◽  
Author(s):  
Paul J. DeMott ◽  
Thomas C. J. Hill ◽  
Christina S. McCluskey ◽  
Kimberly A. Prather ◽  
Douglas B. Collins ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Radiative Forcing ◽  
Marine Boundary Layer ◽  
Strong Increase ◽  
Sea Spray ◽  
Surface Boundary ◽  
Surface Boundary Layer ◽  
Surface Areas ◽  
Order Of Magnitude ◽  
Sea Spray Aerosol

Ice nucleating particles (INPs) are vital for ice initiation in, and precipitation from, mixed-phase clouds. A source of INPs from oceans within sea spray aerosol (SSA) emissions has been suggested in previous studies but remained unconfirmed. Here, we show that INPs are emitted using real wave breaking in a laboratory flume to produce SSA. The number concentrations of INPs from laboratory-generated SSA, when normalized to typical total aerosol number concentrations in the marine boundary layer, agree well with measurements from diverse regions over the oceans. Data in the present study are also in accord with previously published INP measurements made over remote ocean regions. INP number concentrations active within liquid water droplets increase exponentially in number with a decrease in temperature below 0 °C, averaging an order of magnitude increase per 5 °C interval. The plausibility of a strong increase in SSA INP emissions in association with phytoplankton blooms is also shown in laboratory simulations. Nevertheless, INP number concentrations, or active site densities approximated using “dry” geometric SSA surface areas, are a few orders of magnitude lower than corresponding concentrations or site densities in the surface boundary layer over continental regions. These findings have important implications for cloud radiative forcing and precipitation within low-level and midlevel marine clouds unaffected by continental INP sources, such as may occur over the Southern Ocean.

scholarly journals Interrelations between surface, boundary layer, and columnar aerosol properties over a continental urban site

2018 ◽  
Author(s):  
Dongxiang Wang ◽  
Dominika Szczepanik ◽  
Iwona S. Stachlewska
Keyword(s):  
Boundary Layer ◽  
Optical Properties ◽  
Urban Site ◽  
Surface Boundary ◽  
Backscatter Coefficient ◽  
Surface Boundary Layer ◽  
Lidar Observations ◽  
532 Nm ◽  
Aerosol Properties

Abstract. PollyXT Raman Polarization Lidar observations were performed at the Remote Sensing laboratory in Warsaw (52.2109° N, 20.9826° E), Poland, in the framework of the European Aerosol Research Lidar Network (EARLINET) and the Aerosols, Clouds and Trace gases Research Infrastructure (ACTRIS). Data collected in July, August and September of 2013, 2015 and 2016 were analysed using the classical Raman approach. In total 202 sets of profiles of the particle extinction and backscatter coefficient, and linear particle depolarization ratio at 355 nm and 532 nm were derived for statistical investigations (EARLINET/ACTRIS Data Base). The main analysis was focused on intensive optical properties obtained within aerosol boundary layer (ABL). The interrelationships of different optical properties inside ABL are discussed for different periods: entire day, nocturnal time and sunrise/sunset time. In addition, the lidar derived boundary layer optical properties were compared with the columnar daytime aerosol properties derived from radiometer (MFR-7, PolandAOD-NET) and photometer (C318, AERONET). Relationships of these and surface in-situ measurements of particulate matter with an aerodynamic diameter

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