Abstract. This paper presents a summary of the work done within the European Union's Seventh Framework Programme project ECLIPSE (Evaluating the Climate and Air Quality Impacts of Short-Lived Pollutants). ECLIPSE had a unique systematic concept for designing a realistic and effective mitigation scenario for short-lived climate pollutants (SLCPs: methane, aerosols and ozone, and their precursor species) and quantifying its climate and air quality impacts, and this paper presents the results in the context of this overarching strategy. The first step in ECLIPSE was to create a new emission inventory based on current legislation (CLE) for the recent past and until 2050. Substantial progress compared to previous work was made by including previously unaccounted types of sources such as flaring of gas associated with oil production, and wick lamps. These emission data were used for present-day reference simulations with four advanced Earth system models (ESMs) and six chemistry transport models (CTMs). The model simulations were compared with a variety of ground-based and satellite observational data sets from Asia, Europe and the Arctic. It was found that the models still underestimate the measured seasonality of aerosols in the Arctic but to a lesser extent than in previous studies. Problems likely related to the emissions were identified for Northern Russia and India, in particular. To estimate the climate impacts of SLCPs, ECLIPSE followed two paths of research: the first path calculated radiative forcing (RF) values for a large matrix of SLCP species emissions, for different seasons and regions independently. Based on these RF calculations, the Global Temperature change Potential metric for a time horizon of 20 years (GTP20) was calculated for each SLCP emission type. This climate metric was then used in an integrated assessment model to identify all emission mitigation measures with a beneficial air quality and short-term (20 year) climate impact. These measures together defined a SLCP mitigation (MIT) scenario. Compared to CLE, the MIT scenario would reduce global methane (CH4) and black carbon emissions by about 50 and 80%, respectively. For CH4, measures on shale gas production, waste management and coal mines were most important. For non-CH4 SLCPs, elimination of high emitting vehicles and wick lamps, as well as reducing emissions from gas flaring, coal and biomass stoves, agricultural waste, solvents and diesel engines were most important. These measures lead to large reductions in calculated surface concentrations of ozone and particulate matter. We estimate that in the EU the loss of statistical life expectancy due to air pollution was 7.5 months in 2010, which will be reduced to 5.2 months by 2030 in the CLE scenario. The MIT scenario would reduce this value by another 0.9 to 4.3 months. Substantially larger reductions due to the mitigation are found for China (1.8 months) and India (11–12 months). The climate metrics cannot fully quantify the climate response. Therefore, a second research path was taken. Transient climate ensemble simulations with these ESMs were run for the CLE and MIT scenarios, to determine the climate impacts of the mitigation. In these simulations, the CLE scenario resulted in a surface temperature increase of 0.70±0.14 K between the years 2006 and 2050. For the decade 2041–2050, the warming was reduced by 0.22±0.07 K in the MIT scenario, and this result was in almost exact agreement with the response calculated based on the emission metrics (reduced warming of 0.22±0.09 K). The metrics calculations suggest that non-CH4 SLCPs contribute ∼22% to this response and CH4 78%. This could not be fully confirmed by the transient simulations, which attributed about 90% of the temperature response to CH4 reductions. Attribution of the observed temperature response to non-CH4 SLCP emission reductions and black carbon (BC) specifically is hampered in the transient simulations by small forcing and co-emitted species of the emission basket chosen. Nevertheless, an important conclusion is that our mitigation basket as a whole would lead to clear benefits for both air quality and climate. The climate response from BC reductions in our study is smaller than reported previously, largely because our study is one of the first to use fully coupled climate models, where unforced variability and sea-ice responses may counteract the impacts of small emission reductions. The temperature responses to the mitigation were generally stronger over the continents than over the oceans, and with a warming reduction of 0.44 K (0.39–0.49) largest over the Arctic. Our calculations suggest particularly beneficial climate responses in Southern Europe, where the surface warming was reduced by about 0.3 K and precipitation rates were increased by about 15 (6–21) mm yr-1 (more than 4% of total precipitation) from spring to autumn. Thus, the mitigation could help to alleviate expected future drought and water shortages in the Mediterranean area. We also report other important results of the ECLIPSE project.

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[1] Numerical results from a physics-based global magnetohydrodynamic (MHD) model are used to investigate the controlling effects of the interplanetary magnetic field (IMF) components, B Y and B Z , on the location and shape of the magnetopause. The subsolar magnetopause is identified by using the plasma density and velocity, the cusp by using the current density, and the other area by streamlines and the current density. These data are fitted with a three-dimensional surface function constructed by Liu et al. (2012), which allows description of the cusp geometry as well as the north-south asymmetry and azimuthal asymmetry of the magnetopause. A new parameter which depends on the IMF B Y and B Z is introduced to describe the orientation of the elliptical cross section of the magnetopause. Effects of IMF B Y and B Z on the magnetopause configuration parameters are analyzed, and dependence of the magnetopause parameters in the IMF components are obtained. Magnetopause cross section is found to be largely controlled by the IMF clock angle. The stretch direction of the magnetopause cross section is always near the direction of the IMF but is a little closer to the meridional plane than the IMF. Increasing B Y or B Z increases the eccentricity of the magnetopause cross section. This effect is larger for southward IMF than for the northward IMF, and the stretching effect of B Y is smaller than that of B Z .

[1] A three-dimensional adaptive magnetohydrodynamic (MHD) model is used to examine the energy flow from the solar wind to the magnetosphere. Using the model, we directly compute fluxes of mechanical and electromagnetic energy across the magnetopause surface. For northward IMF, most of the energy flux inflow occurs near the polar cusps on magnetopause. The viscous interaction leads the carrying energy plasma enter into high latitudes of the tail magnetopause and then divert to low-latitude regions tangentially, where the plasma gets cooler and denser near the flanks of plasma sheet. For southward IMF, the largest electromagnetic energy input into the magnetosphere occurs at the tail lobe behind the cusps, and largest mechanical energy input occurs at near-equatorial dayside magnetopause. Under southward IMF conditions, mechanical energy transfer is enhanced at the flanks of magnetopause in response to increased IMF magnitude, while more electromagnetic energy input can be identified as increasing solar wind density. Our results suggest that the mechanisms proposed to energy transfer are mainly due to reconnection and viscous interaction processes for northward IMF. For southward IMF, reconnection is the dominant factor in energy transfer. If the electromagnetic energy coupling between the solar wind and the magnetosphere can be interpreted as a proxy for the reconnection efficiency, the average efficiency during northward IMF is about 20% of that for southward IMF under the solar wind conditions we considered.

To investigate the spectral and spatial distribution characteristics of aerosol particles over eastern China, this study conducted a set of aircraft measurements during August 12-28, 2014, over Anhui province, China. The aerosol number concentration and size distributions from five flights as well as the cloud and meteorological parameters were analyzed. In Anhui province, the average number concentration of aerosol particles in the size range of 0.1-3.0 µm was 481 ± 199 cm -3 , and accumulation mode particles accounted for more than 95% of the total aerosol particles. Most of the aerosol particles were concentrated in the layer below 1000 m, where the number concentration decreased with the altitude, except in the presence of thermal inversion layers (TILs). The TILs prevented the vertical transport of aerosol particles, and led to a higher number concentration in the boundary layer. A large fraction of aerosol particles was removed when clouds were present, and the removed in-cloud aerosols lead to an increase in cloud droplet concentrations for the size range of 3.5-10.0 µm. Our results are valuable for understanding the spatial distribution of aerosol particles and their interactions with clouds.

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Indoor localisation has always been a challenging problem due to poor Global Navigation Satellite System (GNSS) availability in such environments. While inertial measurement sensors have become popular solutions for indoor positioning, they suffer large drifts after initialisation. Collaborative positioning enhances positioning robustness by integrating multiple localisation information, especially relative ranging measurements between local users and transmitters. However, not all ranging measurements are useful throughout the whole positioning process and integrating too much data will increase the computation cost. To enable a more reliable positioning system, an adaptive collaborative positioning algorithm is proposed which selects units for the collaborative network and integrates ranging measurement to constrain inertial measurement errors. The algorithm selects the network adaptively from three perspectives: the network geometry, the network size and the accuracy level of the ranging measurements between the units. The collaborative relative constraint is then defined according to the selected network geometry and anticipated measurement quality. In the case of trials with real data, the positioning accuracy is improved by 60% by adjusting the range constraint adaptively according to the selected network situation, while also improving the system robustness. K E Y WO R D S 1. Indoor Positioning.2. Adaptive Weighting. 3. Modified DOP.

To quantify the physical/chemical properties, and the formation and growth processes of aerosol particles on mountainous regions in Southeast China, an intensive field campaign was conducted from April to July 2008 on the top of Mt. Huang (1840m above mean sea level). The average particle number concentration was 2.35×10cm, and the ultrafine particles (<0.1μm) represented 70.5% of the total particle number concentration. Excluding the accumulation mode particles, the average daytime particle number concentrations were prominently higher than those measured at nighttime, suggesting there was a diurnal pattern of changes between planetary boundary layer and free troposphere air. The aerosol spectra were classified into two categories: the first category (FCS) exhibited a clear diurnal cycle, with relatively higher number concentration (3.19×10cm), smaller sizes and air masses from the inland; the second category (SCS) presented less obvious diurnal cycle, with lower number concentration (1.88×10cm), larger sizes and air masses from coastal regions. Air mass sources, weather conditions, and new particle formation (NPF) events were responsible for the differences of these two particle spectra. Six NPF events were identified, which usually began at 10:00-11:00 LT, with the estimated formation rate J in the range of 0.09-0.30cms and the growth rate at 1.42-4.53nmh. Wind speed, sulfur dioxide and ozone concentrations were higher on NPF days than those on non-NPF days, whereas temperature, relative humidity, concentrations of nitrogen oxide and carbonic oxide were lower on NPF days. Sulfur dioxide and ozone might be main potentially precursor gases for those NPF events. The NPF events at Mt. Huang corresponded closely to a southwest winds. These results are useful for improving our understanding of the main factors controlling the variation of aerosol size distribution and NPF events in this region.