0000000000170830
AUTHOR
Jost Heintzenberg
Radiative and dynamic effects of absorbing aerosol particles over the Pearl River Delta, China
Abstract Results are reported from a ground-based measurement campaign conducted in a highly polluted region in southeast of China in October–November 2004. The experiment focused on absorbing aerosol particles and their effects on the solar radiation field and local meteorology. A Raman lidar in conjunction with Sun photometer data measured profiles of particle extinction; ground-based in situ data of aerosol optical properties were collected by nephelometer and absorption photometer. Exceptionally high values of aerosol optical depth of up to 1.5 were observed. The measurements were input to a radiative transfer model, which simulated high solar radiative forcing values for the aerosol pa…
Determination in situ of the size distribution of the atmospheric aerosol
Abstract The aim of the present study was the investigation of the in situ number/size distribution of the atmospheric aerosol in the size range between 0·05 and 2 μm radius. The experimental system consisted of a 4-channel integrating nephelometer, a 2-channel optical particle counter and a condensation nucleus counter. With a new inversion method, which had been tested previously by model computations and by measurements with artificial aerosols, the in situ size distribution was computed from the data of the experimental system.
Cloud phase identification of Arctic boundary-layer clouds from airborne spectral reflection measurements: test of three approaches
Abstract. Arctic boundary-layer clouds were investigated with remote sensing and in situ instruments during the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR) campaign in March and April 2007. The clouds formed in a cold air outbreak over the open Greenland Sea. Beside the predominant mixed-phase clouds pure liquid water and ice clouds were observed. Utilizing measurements of solar radiation reflected by the clouds three methods to retrieve the thermodynamic phase of the cloud are introduced and compared. Two ice indices IS and IP were obtained by analyzing the spectral pattern of the cloud top reflectance in the near infrared (1500–1800 nm wavelength) spectral range whi…
On the Accuracy of the Backward Hemispheric Integrating Nephelometer
Abstract Modified integrating nephelometers are used to measure backward hemispheric scattering coefficients together with total scattering coefficients. These parameters yield information about the chemical nature of the aerosol particles in certain situations involving relatively pure compounds. They are also used as input parameters in climatic models. In this study the effects of the three angular truncations in the modified integrating nephelometers are investigated. We provide a quantitative base to be used with these instruments to determine hemispheric backscatter of aerosol particles and its relationship to the total scattering coefficient.
Blue Moon: Is This a Property of Background Aerosol?
Stellar extinction measurements made at three astronomical observatories showed that on ~50% of the nights the extinction due to aerosol light scattering increased rather than decreased with increasing wavelength (anomalous extinction) for wavelengths close to 500 nm. This extinction behavior is analyzed in this paper and limits are established for the aerosol characteristics necessary for this phenomenon to exist, including geometric standard deviations, imaginary part of refractive index, mean radius, and gaseous NO(2).
Phase partitioning of aerosol particles in clouds at Kleiner Feldberg
The partitioning of aerosol particles between cloud droplets and interstitial air by number and volume was determined both in terms of an integral value and as a function of size for clouds on Mt. Kleiner Feldberg (825 m asl), in the Taunus Mountains north-west of Frankfurt am Main, Germany. Differences in the integral values and the size dependent partitioning between two periods during the campaign were observed. Higher number and volume concentrations of aerosol particles in the accumulation mode were observed during Period II compared to Period I. In Period I on average 87 ± 11% (±one standard deviation) and 73 ± 7% of the accumulation mode volume and number were incorporated into cloud…
Intercomparison and evaluation of global aerosol microphysical properties among AeroCom models of a range of complexity
Many of the next generation of global climate models will include aerosol schemes which explicitly simulate the microphysical processes that determine the particle size distribution. These models enable aerosol optical properties and cloud condensation nuclei (CCN) concentrations to be determined by fundamental aerosol processes, which should lead to a more physically based simulation of aerosol direct and indirect radiative forcings. This study examines the global variation in particle size distribution simulated by 12 global aerosol microphysics models to quantify model diversity and to identify any common biases against observations. Evaluation against size distribution measurements from…