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Abstract.With the increasing trend of charging for externalities and the aim of encouraging the sustainable development of the air transport industry, there is a need to evaluate the social costs of these undesirable side effects, mainly aircraft noise and engine emissions, for different airports. The aircraft noise and engine emissions social costs are calculated in monetary terms for five different sized airports, ranging from hub airports to small regional airports. The number of residences within different levels of airport noise contours and the aircraft noise classifications are the main determinants for accessing aircraft noise social costs.The environmental impacts of aircraft engine emissions include both aircraft landing and take-off and 30-minute cruise. The social costs of aircraft emissions 2 vary by engine type and aircraft category, depending on the damages caused by different engine pollutants on the human health, vegetation, materials, aquatic ecosystem and climate. The results indicate that the relationship appears to be curvilinear between environmental costs and the traffic volume of an airport. The results and methodology of environmental cost calculation could be applied to the proposed European wide harmonised noise charges as well as the social cost benefit analysis of airports.

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1 2 Macquarie Island (MAC) (54.50 °S, 158.94 °E) is an isolated island with modest 3 orography in the midst of the Southern Ocean with precipitation records dating back to 4 1948. These records are of particular interest due to the relatively large biases in the 5 energy and water budgets commonly found in climate simulations and reanalysis 6 products over the region. 7 A basic climatology of the surface precipitation is presented and compared against the 8 ERA-Interim (ERA-I) reanalysis. The annual ERA-I precipitation (953 mm) is found to 9 underestimate the annual MAC precipitation (1023 mm) by 6.8 % from 1979 to 2011.10 The frequency of the 3-h surface precipitation (MAC) is 36.4 % from 2003 to 2011. Light 11precipitation (0.066 ≤ P < 0.5 mm hr -1 ) dominates this precipitation (29.7 %), while the 12 heavy precipitation (P ≥ 1.5 mm hr -1 ) is rare (1.1 %). Drizzle (0 < P < 0.066 mm hr -1 ) is 13 commonly produced by ERA-I (43.9 %), but is weaker than the detectable threshold of 14 MAC. 15Warm rain intensity and frequency from CloudSat products were compared with those 16 from MAC. These CloudSat products also recorded considerable drizzle (16-30 %), but 17 were not significantly different than MAC when P ≥ 0.5 mm hr -1 . 18Heavy precipitation events were, in general, more commonly associated with fronts and 19 cyclonic lows. Some heavy precipitation events were found to arise from weaker fronts 20 and lows that were not adequately represented in the reanalysis products. Yet other heavy precipitation events were observed at points/times not associated with either 1 fronts or cyclonic lows. Two case studies are employed to further examine this. 2 1 The atmospheric environment over the Southern Ocean (SO) is unique: the lack of 2 terrestrial and anthropogenic aerosols creates a pristine environment with few cloud 3 condensation nuclei (Yum and Hudson 2005; Gras 1995). Strong winds produce large 4 waves that, when coupled together, generate large concentrations of sea spray (Murphy 5 et al. 1998). Recent satellite observations of the cloud-top thermodynamic phase suggest 6 that vast fields of clouds composed of supercooled liquid water (SLW) are dominant 7 over the region (Hu et al. 2010; Morrison et al. 2011; Huang et al. 2012a), and are 8 considerably different from those over the North Atlantic (Huang et al. 2015). Limited 9 in-situ cloud observations have found that SLW can exist throughout the entire depth of 10 these clouds, which are often hundreds of meters thick (Chubb et al. 2013; Morrison et 11 al. 2010; Ryan and King 1997; Mossop et al. 1970). 12 Chubb et al. (2013) further observed that the precipitation under these SLW clouds 13 (cloud-top temperature down to -22 °C) was of various thermodynamic phases 14 (glaciated, mixed-phase or even entirely supercooled liquid), highlighting our very 15 limited understanding of the nature of precipitation over the SO. Yet such an 16 understanding is necessary to close both the water and energy budgets over this region 17 that covers 15 % of the Earth's surface. T...

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