Aerosol direct effect

For the realisation of all aerosol forcing mechanisms in integrated systems it is necessary to improve not only ACTMs, but also NWP HIRLAM. The boundary layer structure and processes, including radiation transfer (Savijarvi 1990), cloud development and precipitation must be improved. Convection and condensation schemes need to be adjusted to take the aerosol-microphysical interactions into account, and the radiation scheme needs to be modified to include the aerosol effects. Incorporation of the aerosol direct effects (radiation forcing) is very problematic within the Savijarvi (1990) radiation scheme. 

GSD GHG plus sulfate aerosols (direct effect only) 1860-2050... 

Aerosol-Based Direct Fluorination. A technology that works on Hter and half-Hter quantities has been introduced (40—42). This new aerosol technique, which functions on principles similar to LaMar direct fluorination (Fig. 5), uses fine aerosol particle surfaces rather than copper filings to maintain a high surface area for direct fluorination. The aerosol direct fluorination technique has been shown to be effective for the synthesis of bicycHc perfluorocarbon such as perfluoroadamantane, perfluoroketones, perfluoroethers, and highly branched perfluorocarbons. 

Irregular respiration was observed in both male and female rats after a 4-hour nose-only inhalation exposure to aerosolized endosulfan (Hoechst 1983a). In both male and female rats, dyspnea was observed at the lowest concentrations tested (12.3 and 3.6 mg/m for males and females, respectively). Autopsies of the rats that died revealed dark-red, pinhead-sized foci on the lungs. It is unclear whether these effects represent direct effects of inhaled endosulfan on respiratory tissues or whether they are secondary to central nervous system effects on respiratory function. No treatment-related effects were... 

In short, the direct effects of aerosol particles in terms of backscattering solar radiation out to space and hence leading to cooling are reasonably well understood qualitatively and provided the aerosol composition, concentrations, and size distribution are known, their contribution can be treated quantitatively as well. However, major uncertainties exist in our knowledge of the physical and chemical properties, as well as the geographical and temporal variations, of aerosol particles and it is these uncertainties that primarily limit the ability to accurately quantify the direct effects at present. 

As discussed in Section C.la, sea salt particles in the marine boundary layer have been shown to likely play a major role in backscattering of solar radiation (Murphy et al., 1998), i.e., to the direct effect of aerosol particles. However, they also contribute to the indirect effect involving cloud formation, since they can also act as CCN. Since such particles are a natural component of the marine atmosphere, their contribution will not play a role in climate change, unless their concentration were somehow to be changed by anthropogenic activities, e.g., through changes in wind speed over the... 

The climate effects of atmospheric aerosol particles are a matter of continuous interest in the research community. The aerosol-climate effects are divided into two groups The direct effect represents the ability of the particle population to absorb and scatter short-wave radiation - directly affecting the radiation balance. These direct effects depend primarily on the aerosol optical properties and particle number size distribution, as the particle size significantly affects the scattering efficiency of... 

Even though there is no significant change in the CCN number concentrations between days of the week, this is not yet the complete picture of potential aerosol-cloud weekend effects. There are many other potential aerosol processes, such as semi-direct effect, which could have significant effect on the local meteorology. Also, the CCN number concentrations have a weak weekday variation within the cities, which could then lead to meteorological weekend effect directly above the urban environment. However, as the urban or semi-urban areas cover spatially quite small area of the Europe (around 5%) [27], the weekend effect is then of much more a local effect, if it exists at all. 

Giorgi F. Bi X. and Qian Y. (2003). Indirect and direct effects of anthropogenic sulfate on the climate of East Asia as simulated with a regional coupled climate-chemistry/aerosol model. Climatic Change, 58, 345-376. 

Podgorny I.A. and Ramanathan V. (2001). A modeling study of the direct effect of aerosols over the tropical Indian Ocean. J. Geophys. Res., 104(20), 24097-24104. 

It is necessary to highlight those effects of aerosols and other chemical species on meteorological parameters have many different pathways (such as, direct, indirect and semi-direct effects) and they have to be prioritized and considered in... 

What is the relative importance of aerosol direct and indirect effects in the... 

A further effect of aerosols is the evaporation of clouds as a consequence of atmospheric heating caused by absorption of solar radiation by aerosols. This phenomenon reduces cloudiness, increasing absorption of solar radiation by the Earth-atmosphere system, a so-called semi-direct effect (Hansen et al., 1997 Satheesh and Ramanathan, 2000 Lohmann and Feichter, 2001). 

The specific mechanism of toxicity of kerosene has not been completely determined. The primary risk from ingestion of kerosene is aspiration during emesis, which may cause pneumonitis. The biochemical mechanism of lung response to large concentrations of aerosolized kerosene (resulting in bronchocon-striction and asthma-like symptoms) may involve the parasympathetic nervous system via a direct effect on the vagus nerve or by inhibition of acetylcholinesterase. The mechanism(s) of central nervous system (CNS) depression from kerosene exposure has not been elucidated, but undoubtedly includes disruption of the membranes of nerve cells. 

---