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From past many decades, the integrating nephelometers are generally used to measure the aerosol scattering coefficient for ground level at different wavelengths. In recent years, the research focus has been shifted toward the airborne observations using either tethered balloons or drones. For this particular purpose, one needs light-weight instruments which are capable of measuring the aerosol scattering coefficient suitable for airborne activities. Thus, we report the design and development of a light-weight scattering coefficient counter (weight ~ 500 g, 7″ × 3″) with high sensitivity. This instrument has been specifically designed and developed for the measurement of aerosol scattering coefficient at 633 nm wavelength. The aerosol scattering coefficient calculation becomes extremely important for modeling aerosol optical/radiative properties. Delhi is one of the regions with high aerosol loadings, so one needs such Light-weight instruments for the aerosol scattering coefficient measurements. At present, this instrument has only been evaluated at ground level. But, before using the developed instrument for airborne observations, there is a strong need for comparison of the instrument against routinely used nephelometers for performance evaluation. Comparisons were performed between the light-weight scattering coefficient counter and high-end AURORA 3000 Nephelometer for two different seasons. For both the seasons, i.e., the monsoon season (July 25–August 24, 2017) and the winter season (February 1–28, 2018), we found a strong correlation (i.e., R2 = 0.99). However, the highest value of scattering coefficient was found to be 98 ± 32 Mm−1 with a mean value of 55 Mm−1 for the monsoon season, while the same for the winter season was observed to be 270 ± 108 Mm−1 with a mean value of 165 Mm−1. This light-weight instrument could be a potential instrument for aerosol scattering observations, especially for airborne platforms with payload mass limitations.

We introduce the path length probability density function (PPDF) method, which is based on an equivalence theorem and parameterizes the aerosol scattering effect by adding four factors to the atmospheric transmittance model. Using simulated observations in the O2-A band, we examined the utility of the PPDF-based method to account for the aerosol scattering effect. First, observations were simulated using a forward model under different aerosol conditions; PPDF factors were then retrieved using an optimal estimation method; PPDF factors were used to reconstruct the observations; and finally, simulated true observations and reconstructions were compared. Analysis of the difference between the true observations and reconstructions confirmed the utility of the PPDF-based method. Additionally, the O2 band was demonstrated to be an efficient observing band for assisting the remote sensing of atmospheric trace gases in the near-infrared band.

The transparency of a molecular gaseous medium comprising spherical aerosol particles is calculated. The characteristics of the transformed radiant energy that has passed through particles with different microphysical properties are analyzed. It is established that the joint effect of the molecular absorption and aerosol scattering in the IR range must be considered. Based on the characteristics of scattering particles, the boundary conditions are written that allow the molecular absorption and scattering to be considered separately.

The data, measured by a three-wavelength Integrating Nephelometer over Lanzhou City during the winters of 2001/2002 and 2002/2003 respectively, have been analyzed for investigating the scattering properties of atmospheric aerosols and exploring their relationship and the status of air pollution. The aerosol particle volume distribution is inverted with the measured spectral scattering coefficients. The results show that the daily variation of the aerosol scattering coefficients is in a tri-peak shape. The average ratio of backscattering coefficient to total scattering coefficient at 550 nm is 0.158; there exists an excellent correlation between the scattering coefficients and the concentration of PM10. The average ratio of the concentration of PM10 to the scattering coefficients is 0.37 g m−2, which is contingent on the optical parameters of aerosol particles such as the size distribution, etc.; an algorithm is developed for inverting the volume distribution of aerosol particles by using the histogram and Monte-Carlo techniques, and the test results show that the inversion is reasonable.

Particles lofted into the atmosphere by desert dust storms can disperse widely and affect climate directly through aerosol scattering and absorption. They can also affect it indirectly by changing the scattering properties of clouds and, because desert dusts are particularly active ice-forming agents, by affecting the formation and thermodynamic phase of clouds. Here I show that dust storms that occurred in Asia early in 2004 created unusual ice clouds over Alaska at temperatures far warmer than those expected for normal cirrus-cloud formation.

The total radiance observed by satellite-borne ocean color sensors results from several contributions: the atmospheric molecular and aerosol scattering, the sea surface reflectance and the water leaving radiance. In order to apply these ocean color sensor data to access the ocean parameters, atmospheric correction should be undertaken in advance to extract the water leaving radiance that is relevant to the ocean parameters. The aim of this study is to establish one atmospheric correction process for the Ocean Color Imager (OCI) of ROCSAT-1, and some pre-launch simulation results are demonstrated. The simulation shows that the water leaving radiance estimation seems to be reliable by the ocean color radiance algorithm proposed in this paper, because the estimated total pigment concentration seems to be reasonable. Further investigations done in this study using SeaWiFS data reveal that the water leaving radiance is somewhat overestimated in comparison with ship measurements because of the underestimated aerosol scattering. The reason for this underestimation is probably the inconsistent marine aerosol type and size distribution between the real and input atmospheric parameters. The simulated result also shows the sun glint effect is significant and plays the most important role in the radiance contributions of OCI imagery. Consequently, choosing the most suitable acquiring time of OCI in order to avoid the sun glint effect will be very important in future OCI operation scheduling.

The atmospheric aerosol scattering coefficientσ s , measured for more than a year more or less continuously in Vienna, Austria, exhibits unexpected patterns of variation. Apart from the usual ones following changes in relative humidity or traffic characteristics,a distinctive pattern is found before a change in air mass.σ s rises by a factor of 1.5 to 2 some hours (usually two or three) before the passage of the front without a corresponding change in emission characteristics or relative humidity and then falls either below or to its previous level. This behaviour ofσ s occurred at all frontal passages during the sampling period at all times of day and of year except when the wind speeds were very high. An explanation is attempted by examining the mixing heights before a change in airmass since a reduced vertical dispersion due to pre-frontal changes of stability could account for the increase inσ s (and thus the aerosol concentration). It has been found that calculated mixing heights are reduced by nearly the same factor as the value ofσ s is increased before the front. After the front the factors are similar, but then the aerosol concentration depends also on the origin of the air mass.

A critical examination of the wavelength exponent α embodied in the well-knownAngstrom's proposition for coefficient of aerosol scattering expressed bymhβ λ−a has been made. It is observed that, in North and Central India, for most part of the year the exponent α is zero and sometimes even negative. This shows that the aerosol scattering is independent of wavelength and neutral.