Browsing by Author "Sugimoto, N."
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- ItemDust events in Beijing, China (2004–2006): Comparison of ground-based measurements with columnar integrated observations(München : European Geopyhsical Union, 2009) Wu, Z.J.; Cheng, Y.F.; Hu, M.; Wehner, B.; Sugimoto, N.; Wiedensohler, A.Ambient particle number size distributions spanning three years were used to characterize the frequency and intensity of atmospheric dust events in the urban areas of Beijing, China in combination with AERONET sun/sky radiometer data. Dust events were classified into two types based on the differences in particle number and volume size distributions and local weather conditions. This categorization was confirmed by aerosol index images, columnar aerosol optical properties, and vertical potential temperature profiles. During the type-1 events, dust particles dominated the total particle volume concentration (<10 μm), with a relative share over 70%. Anthropogenic particles in the Aitken and accumulation mode played a subordinate role here because of high wind speeds (>4 m s−1). The type-2 events occurred in rather stagnant air masses and were characterized by a lower volume fraction of coarse mode particles (on average, 55%). Columnar optical properties showed that the superposition of dust and anthropogenic aerosols in type-2 events resulted in a much higher AOD (average: 1.51) than for the rather pure dust aerosols in type-1 events (average AOD: 0.36). A discrepancy was found between the ground-based and column integrated particle volume size distributions, especially for the coarse mode particles. This discrepancy likely originates from both the limited comparability of particle volume size distributions derived from Sun photometer and in situ number size distributions, and the inhomogeneous vertical distribution of particles during dust events.
- ItemLidar measurements for desert dust characterization: An overview(London : Hindawi, 2012) Mona, L.; Liu, Z.; Müller, D.; Omar, A.; Papayannis, A.; Pappalardo, G.; Sugimoto, N.; Vaughan, M.We provide an overview of light detection and ranging (lidar) capability for describing and characterizing desert dust. This paper summarizes lidar techniques, observations, and fallouts of desert dust lidar measurements. The main objective is to provide the scientific community, including nonpractitioners of lidar observations with a reference paper on dust lidar measurements. In particular, it will fill the current gap of communication between research-oriented lidar community and potential desert dust data users, such as air quality monitoring agencies and aviation advisory centers. The current capability of the different lidar techniques for the characterization of aerosol in general and desert dust in particular is presented. Technical aspects and required assumptions of these techniques are discussed, providing readers with the pros and cons of each technique. Information about desert dust collected up to date using lidar techniques is reviewed. Lidar techniques for aerosol characterization have a maturity level appropriate for addressing air quality and transportation issues, as demonstrated by some first results reported in this paper.
- ItemRecommendations for reporting "black carbon" measurements(München : European Geopyhsical Union, 2013) Petzold, A.; Ogren, J.A.; Fiebig, M.; Laj, P.; Li, S.-M.; Baltensperger, U.; Holzer-Popp, T.; Kinne, S.; Pappalardo, G.; Sugimoto, N.; Wehrli, C.; Wiedensohler, A.; Zhang, X.-Y.Although black carbon (BC) is one of the key atmospheric particulate components driving climate change and air quality, there is no agreement on the terminology that considers all aspects of specific properties, definitions, measurement methods, and related uncertainties. As a result, there is much ambiguity in the scientific literature of measurements and numerical models that refer to BC with different names and based on different properties of the particles, with no clear definition of the terms. The authors present here a recommended terminology to clarify the terms used for BC in atmospheric research, with the goal of establishing unambiguous links between terms, targeted material properties and associated measurement techniques.
- ItemRelationships between submicrometer particulate air pollution and air mass history in Beijing, China, 2004–2006(München : European Geopyhsical Union, 2008) Wehner, B.; Birmili, W.; Ditas, F.; Wu, Z.; Hu, M.; Liu, X.; Mao, J.; Sugimoto, N.; Wiedensohler, A.The Chinese capital Beijing is one of the global megacities where the effects of rapid economic growth have led to complex air pollution problems that are not well understood. In this study, ambient particle number size distributions in Beijing between 2004 and 2006 are analysed as a function of regional meteorological transport. An essential result is that the particle size distribution in Beijing depends to large extent on the history of the synoptic scale air masses. A first approach based on manual back trajectory classification yielded differences in particulate matter mass concentration by a factor of two between four different air mass categories, including three main wind directions plus the case of stagnant air masses. A back trajectory cluster analysis refined these results, yielding a total of six trajectory clusters. Besides the large scale wind direction, the transportation speed of an air mass was found to play an essential role on the PM concentrations in Beijing. Slow-moving air masses were shown to be associated with an effective accumulation of surface-based anthropogenic emissions due to both, an increased residence time over densely populated land, and their higher degree of vertical stability. For the six back trajectory clusters, differences in PM1 mass concentrations by a factor of 3.5, in the mean air mass speed by a factor of 6, and in atmospheric visibility by a factor of 4 were found. The main conclusion is that the air quality in Beijing is not only degraded by anthropogenic aerosol sources from within the megacity, but also by sources across the entire Northwest China plain depending on the meteorological situation.