An overview on the data of columnar aerosol properties measured in Northern Europe is provided. Apart from the necessary data gathered in the Arctic, the knowledge of the aerosol loading in nearby ...areas (e.g. sub-Arctic) is of maximum interest to achieve a correct analysis of the Arctic aerosols and transport patterns. This work evaluates data from operational sites with sun photometer measurements belonging either to national or international networks (AERONET, GAW-PFR) and programs conducted in Scandinavia and Svalbard. We enumerate a list of sites, measurement type and periods together with observed aerosol properties. An evaluation and analysis of aerosol data was carried out with a review of previous results as well. Aerosol optical depth (AOD) and Ångström exponent (AE) are the current parameters with sufficient long-term records for a first evaluation of aerosol properties. AOD (500 nm) ranges from 0.08 to 0.10 in Arctic and sub-Arctic sites (Ny-Ålesund: 0.09; Andenes: 0.10; Sodankylä: 0.08), and it is somewhat higher in more populated areas in Southern Scandinavia (AOD about 0.10–0.12 at 500 nm). On the Norwegian coast, aerosols show larger mean size (AE = 1.2 at Andenes) than in Finland, with continental climate (AE = 1.5 at Sodankylä). Columnar particle size distributions and related parameters derived from inversion of sun/sky radiances were also investigated. This work makes special emphasis in the joint and collaborative effort of the various groups from different countries involved in this study. Part of the measurements presented here were involved in the IPY projects Polar-AOD and POLARCAT.
► Different AOD seasonality is found in Svalbard, northern and southern Scandinavia. ► In the European sub-Arctic region (about 65–70°N) the spring haze is not persistent. ► Sources in Eastern Europe produce a spring AOD peak over southern Scandinavia. ► Fine mode aerosols are predominant and their variations determine the seasonal aerosol variability. ► The coarse mode aerosol concentrations are very low except for coastal sites.
Abstract Aerosols, transported from distant source regions, influence the Arctic surface radiation budget. When deposited on snow and ice, carbonaceous particles can reduce the surface albedo, which ...accelerates melting, leading to a temperature-albedo feedback that amplifies Arctic warming. Black carbon (BC), in particular, has been implicated as a major warming agent at high latitudes. BC and co-emitted aerosols in the atmosphere, however, attenuate sunlight and radiatively cool the surface. Warming by soot deposition and cooling by atmospheric aerosols are referred to as “darkening” and “dimming” effects, respectively. In this study, climatologies of spectral aerosol optical depth AOD (2001–2011) and Equivalent BC (EBC) (1989–2011) from three Arctic observatories and from a number of aircraft campaigns are used to characterize Arctic aerosols. Since the 1980s, concentrations of BC in the Arctic have decreased by more than 50% at ground stations where in situ observations are made. AOD has increased slightly during the past decade, with variations attributed to changing emission inventories and source strengths of natural aerosols, including biomass smoke and volcanic aerosol, further influenced by deposition rates and airflow patterns.
The eruptions of the Kasatochi volcano on 7 and 8 August 2008 led to an enhanced stratospheric aerosol load which was studied with the Koldewey Aerosol Raman Lidar (KARL) and the Micro Pulse Lidar ...(MPL) at the French‐German Arctic Research Base AWIPEV in Ny‐Ålesund, Spitsbergen at 78.55°N, 11.56°E. During all KARL measurements from 15 August to 24 September 2008 (approximately 30 h of data), we detected distinct layers of enhanced aerosol backscatter in the lower stratosphere and the tropopause region, whose origination at the Kasatochi site can be shown by trajectory calculations. We found a 125% increase in aerosol optical depth compared to the mean values from 2004 to 2007 at 3 weeks after the eruption, validated by sunphotometer measurements. Differences in volume depolarization and color ratio signatures of the layers indicate a sinking movement of the bigger particles to the layer bottom. Furthermore, within higher stratospheric aerosol layers monitored after 25 August 2008, we observed the volume depolarization maximum to be up to 0.8 km below the backscatter maximum. Backscatter and depolarization measurements from 1 September 2008, on which data were collected over 13 h during daylight and darkness, are analyzed in detail. Calculations of the lidar ratio in the lowest aerosol layer as well as the estimation of microphysical parameters of the aerosol particles were performed.
During March 2008 photometer observations of Arctic aerosol were performed both at a Russian ice-floe drifting station (NP-35) at the central Arctic ocean (56.7–42.0° E, 85.5–84.2° N) and at ...Ny-Ålesund, Spitsbergen (78.9° N, 11.9° E). Next to a persistent increase of AOD over NP-35, two pronounced aerosol events have been recorded there, one originating from early season forest fires close to the city of Khabarovsk (“Arctic Smoke”), the other one showed trajectories from central Russia and resembled more the classical Arctic Haze. The latter event has also been recorded two days later over Ny-Ålesund, both in photometer and lidar. From these remote sensing instruments volume distribution functions are derived and discussed. Only subtle differences between the smoke and the haze event have been found in terms of particle microphysics. Different trajectory analysis, driven by NCEP and ECMWF have been performed and compared. For the data set presented here the meteorological field, due to sparseness of data in the central Arctic, mainly limits the precision of the air trajectories.
► A case of each Arctic Haze and Arctic Smoke (biomass burning) is presented. ► Photometer and lidar data are analyzed from 2 Arctic sites. ► Microphysical aerosol properties are similar for both cases. ► The applicability and limitations of air trajectories are discussed. ► In the Arctic the driving meteorological field limits the trajectories’ precision.
Accuracy requirements for aerosol optical depth (AOD) in polar regions are much more stringent than those usually encountered in established sun photometer networks, while comparability of data from ...different archive centres is a further important issue. Therefore, two intercomparison campaigns were held during spring 2006 at Ny-Ålesund (Svalbard) and autumn 2008 at Izaña (Tenerife) within the framework of the IPY POLAR-AOD project, with the participation of various research institutions routinely employing different instrument models at Arctic and Antarctic stations. As reported here, a common algorithm was used for data analysis with the aim of minimizing a large part of the discrepancies affecting the previous studies. During the Ny-Ålesund campaign, spectral values of AOD derived from measurements taken with different instruments were found to agree, presenting at both 500nm and 870nm wavelengths average values of root mean square difference (RMSD) and standard deviation of the difference (SDD) equal to 0.003. Correspondingly, the mean bias difference (MBD) varied mainly between −0.003 and +0.003 at 500nm, and between −0.004 and +0.003 at 870nm. During the Izaña campaign, which was also intended as an intercalibration opportunity, RMSD and SDD values were estimated to be equal to 0.002 for both channels on average, with MBD ranging between −0.004 and +0.004 at 500nm and between −0.002 and +0.003 at 870nm. RMSD and SDD values for Ångström exponent α were estimated equal to 0.06 during the Ny-Ålesund campaign and 0.39 at Izaña. The results confirmed that sun photometry is a valid technique for aerosol monitoring in the pristine atmospheric turbidity conditions usually observed at high latitudes.
► Two sun photometer comparison campaigns were conducted for the POLAR-AOD project. ► AOD mean bias differences were found to be within ±0.004 at all wavelengths. ► Ångström exponent α was estimated to be within 0.06 and 0.39 for the two campaigns.
The present study mainly focuses on the mixing states of aerosol constituents and their vertical distribution in spring Arctic troposphere during the ASTAR 2000 campaign (T. Yamanouchi et al., Arctic ...Study of Tropospheric Aerosol and Radiation (ASTAR) campaign: An overview and first results, submitted to Bulletin of the American Meteorological Society, 2002) (hereinafter referred to as Yamanouchi et al., submitted manuscript, 2002). Sulfate and soot were identified as major aerosol under both Arctic haze and background conditions, and sea‐salts are major only in lower troposphere (<3 km above sea level). Mineral/dusts and unknown species were obtained as minor constituents during the ASTAR 2000 campaign. Airborne aerosol measurements were carried out under the Arctic haze (23 March), and aerosol‐enriched (20 March and 12 April) conditions. The highest relative abundance of soot (∼94.7%) was observed in free troposphere on 23 March, when the heaviest Arctic haze condition during the ASTAR 2000 campaign (Yamanouchi et al., submitted manuscript, 2002) was transported directly from Russian industrial regions to the measuring area for several days. Moreover, whereas the external mixing of soot and sulfate dominated under the Arctic haze and aerosol enriched conditions, in the background conditions the internal mixing is dominant. On the other hand, most of aerosol particles containing sulfate had the external mixing states with soot and other aerosol constituents in the free troposphere under both the Arctic haze and background conditions. Sea‐salts are dominant only in the lower troposphere (<3 km asl), although a few sea‐salt particles were observed in the middle‐upper troposphere (3–7 km). Some sea‐salt particles were modified (Cl− depleted) in the lower troposphere (<3 km) during the ASTAR 2000 campaign.
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