Renate Treffeisen

In-situ airborne observations of the microphysical properties of the Arctic tropospheric aerosol during late spring and summer

In-situ aerosol data collected in the Arctic troposphere during a three-week period in 2004 were analysed. The measurements took place during late spring, i.e., at the time of the year when the characteristics of the aerosol distribution change from being accumulation-mode dominated to being primarily of the Aitken-mode type, a process that previously has been observed in the boundary layer. To address the question whether this transition is also detectable in the free troposphere of an aircraft-measured data from the ASTAR 2004 campaign were analysed. In this study, we present vertically as well as temporally results from both ground-based and airborne measurements of the total number concentrations of particles larger than 10 and 260 nm. Aircraft-measured size distributions of the aerosol ranging from 20 to 2200 nm have been evaluated with regard to conditions in the boundary layer as well as in the free troposphere. Furthermore an analysis of the volatile fraction of the aerosol population has been performed both for the integrated and size-distributed results. From these investigations we find that the transition takes place in the entire troposphere.

Interpretation of Arctic aerosol properties using cluster analysis applied to observations in the Svalbard area

Atmospheric aerosols play an important role in global climate change, directly through radiative forcing and indirectlythrough their effect on cloud properties. Numerous measurements have been performed in the last three decades inorder to characterize polar aerosols. Information about aerosol characteristics is needed to calculate induced changes inthe Earth’s heat balance. However, this forcing is highly variable in space and time. Accurate quantification of forcingby aerosols will require combined efforts, assimilating information from different sources such as satellite, aircraft andsurface-based observations. Adding to the complexity of the problem is that the measurements themselves are oftennot directly comparable as they vary in spatial/temporal resolution and in the basic properties of the aerosol that theymeasure. Therefore it is desirable to close the gap between the differences in temporal and spatial resolution and coverageamong the observational approaches. In order to keep the entire information content and to treat aerosol variability ina consistent and manageable way an approach has to be achieved which enables one to combine these data. This studypresents one possibility for linking together a complex Arctic aerosol data set in terms of parameters, timescale and placeof measurement as well as meteorological parameters. A cluster analysis was applied as a pattern recognition technique.The data set is classified in clusters and expressed in terms of mean statistical values, which represent the entire databaseand its variation. For this study, different time-series of microphysical, optical and chemical aerosol parameters aswell as meteorological parameters were analysed. The database was obtained during an extensive aerosol measurementcampaign, the ASTAR 2000 (Arctic Study of Tropospheric Aerosol and Radiation) field campaign, with coordinatedsimultaneous ground-based and airborne measurements in the vicinity of Spitsbergen (Svalbard). Furthermore, longtermmeasurements at two ground-based sites situated at different altitudes were incorporated into the analysis. Theapproach presented in this study allows the necessary linking of routine long-term measurements with short-termextensive observations. It also involves integration of intermittent vertical aerosol profile measurements. This is usefulfor many applications, especially in climate research where the required data coverage is large.

Stratospheric Aerosol and Gas Experiment (SAGE) II and III aerosol extinction measurements in the Arctic middle and upper troposphere

In recent years, substantial effort has been expended toward understanding the impact of tropospheric aerosols on Arctic climate and chemistry. A significant part of this effort has been the collection and documentation of extensive aerosol physical and optical property data sets. However, the data sets present significant interpretive challenges because of the diverse nature of these measurements. Among the longest continuous records is that by the spaceborne Stratospheric Aerosol and Gas Experiment (SAGE) II. Although SAGE tropospheric measurements are restricted to the middle and upper troposphere, they may be able to provide significant insight into the nature and variability of tropospheric aerosol, particularly when combined with ground and airborne observations. This paper demonstrates the capacity of aerosol products from SAGE II and its follow-on experiment SAGE III to describe the temporal and vertical variations of Arctic aerosol characteristics. We find that the measurements from both instruments are consistent enough to be combined. Using this combined data set, we detect a clear annual cycle in the aerosol extinction for the middle and upper Arctic troposphere.

Where does the optically detectable aerosol in the European Arctic come from

In this paper, we pose the question where the source regions of the aerosol, which occurs in the European Arctic, are located. Long-term aerosol optical depth (AOD) data from Ny-Ålesund and Sodankylä as well as short-term data from a campaign on a Russian drifting station were analysed by air backtrajectories, analysis of the general circulation pattern and a correlation to chemical composition from in-situ measurements. Surprisingly, our data clearly shows that direct transport of pollutants from Europe does not play an important role. Instead, Arctic haze in Ny-Ålesund has been found for air masses from the Eastern Arctic, while events with increased AOD but chemically more diverse composition have been found for air from Siberia or the central Arctic. Moreover, the AOD in Ny-Ålesund does not depend on the North Atlantic Oscillation (NAO). Hence, either the pollution pathways of aerosol are more complex or aerosol is significantly altered by clouds.

Quantification of source region influences on the ozone burden

Abstract A project was performed to quantify different influences on the ozone burden. It could be shown that large-scale meteorological influences determine a very large percentage of the ozone concentration. Local measures intended to reduce peak ozone concentrations in summer turn out to be not very effective as a result. The aim of this paper is to quantify regional emission influences on the ozone burden. The investigation of these influences is possible by comparison of the ozone (O3) and oxidant (Ox=O3+NO2) concentrations at high-elevation sites downwind and upwind of a source region by using back trajectories. It has been shown that a separation between large-scale influenced meteorological and regional ozone burdens at these sites is possible. This method is applied for an important emission area in Germany—the Ruhrgebiet. On average, no significant ozone contribution of this area to the regional ozone concentration could be found. A large part of the ozone concentration is highly correlated with synoptic weather systems, which exhibit a dominant influence on the local ozone concentrations. Significant contributions of related photochemical ozone formation of the source area of 13–15% have been found only during favourable meteorological situations, identified by the hourly maximum day temperature being above 25°C. This is important with respect to the EU daughter directive to EU 96/62/EC (Official Journal L296 (1996) 55) because Member States should explore the possibilities of local measures to avoid the exceedance of threshold values and, if effective local measures exist, to implement them.

The Web Portal ‘meereisportal.de’ in Context of ESKP

The new knowledge and data portal ‘meereisportal.de’ is a contribution to the cross-linking of scientifically qualified information on climate change. It focuses deliberately on the theme ‘sea ice in both Polar Regions’. With the establishment of ‘meereisportal.de’, science adapts to changing societal demands and embarks on new ways of communication between science and society.

Wissenschaftliche Information für die Anwendung

Der Austausch von Wissen und Information zwischen verschiedenen gesellschaftlichen Gruppen ist oft nicht trivial. Vertreter aus der Offentlichkeit, verschiedenen Fachkreisen und Behorden oder aus der Wissenschaft generieren sehr unterschiedliches Wissen unter Einbeziehung von unterschiedlichen Graden der Problemorientierung und in ihrer jeweiligen Sprache. Zur Uberwindung dieser Barrieren stehen verschiedene Instrumente zur Verfugung. In diesem Artikel werden drei weitverbreitete Formen des Wissenstransfers diskutiert: (1) Assessments mit ihren verschiedenen Formen z. B. auf unterschiedlichen raumlichen Skalen, (2) Indikatoren mit moglichen Rahmenkonzepten, Indikatorensatze und Formen der Evaluierung und (3) web-basierte Plattformen als einfache Moglichkeit der Verbreitung von aktuellen Informationen. Dabei werde zwei Beispiele ausfuhrlich dargestellt, namlich das am Klimaburo fur Polargebiete und Meeresspielgel konzipierte Meereisportal und der am Mitteldeutschen Klimaburo entwickelte Deutsche Durremonitor.