Ground level enhancements (GLEs), which occur when high energy solar protons reach Earth, are a considerable space weather hazard for aviation activities. Neutron monitor (NM) observations of these events are the key input to operational models of ionizing radiation at aviation altitudes. Similarly, the NM data is key to techniques for deriving anisotropic solar proton spectra during GLEs. A higher density of observations is desirable for both purposes. In this paper, a simple way of improving the density of observations for large events is presented: the compact neutron monitor (CNM). This monitor uses the same unleaded detectors as soil moisture sensing networks. Three years of data from the CNM located in Guildford, UK, is presented. The solar cycle variation in cosmic rays is observed, alongside 4 Forbush decreases of varying magnitude. No GLEs were observed during this time, due to a lack of any events of sufficient magnitude to be observed. A future CNM station near Lerwick, UK is briefly described in addition to the Guildford station. The implications of the observations to date are discussed in the context of GLE detection. The CNM is complementary to existing and emerging NM designs, and may be suitable for use as a reference point for the soil moisture monitoring networks. The suitability of the CNM to GLE detection can be extrapolated to the soil moisture networks in the case of large GLEs; in the event of one occurring, the data may provide unprecedented spatial resolution.

The light scattering and absorption properties of anthropogenic aerosol particles such as soot aggregates are complicated in the temporal and spatial distribution, which introduce uncertainty of radiative forcing on global climate change. In order to study the single scattering properties of anthorpogenic aerosol particles, the structures of these aerosols such as soot paticles and soot-containing mixtures with the sulfate or organic matter, are simulated using the parallel diffusion limited aggregation algorithm (DLA) based on the transmission electron microscope images (TEM). Then, the single scattering properties of randomly oriented aerosols, such as scattering matrix, single scattering albedo (SSA), and asymmetry parameter (AP), are computed using the superposition T-matrix method. The comparisons of the single scattering properties of these specific types of clusters with different morphological and chemical factors such as fractal parameters, aspect ratio, monomer radius, mixture mode and refractive index, indicate that these different impact factors can respectively generate the significant influences on the single scattering properties of these aerosols. The results show that aspect ratio of circumscribed shape has relatively small effect on single scattering properties, for both differences of SSA and AP are less than 0.1. However, mixture modes of soot clusters with larger sulfate particles have remarkably important effects on the scattering and absorption properties of aggregated spheres, and SSA of those soot-containing mixtures are increased in proportion to the ratio of larger weakly absorbing attachments. Therefore, these complex aerosols come from man made pollution cannot be neglected in the aerosol retrievals. The study of the single scattering properties on these kinds of aggregated spheres is important and helpful in remote sensing observations and atmospheric radiation balance computations. (C) 2012 Elsevier Ltd. All rights reserved.