Description: In this work multi wavelength Raman lidar data from Ny-Ålesund, Spitsbergen have been analysed for the spring 2014 Arctic haze season, as part of the iAREA campaign. Typical values and probability distributions for aerosol backscatter, extinction and depolarisation, the lidar ratio and the color ratio for 4 different altitude intervals within the troposphere are given. These quantities and their dependencies are analysed and the frequency of altitude-dependent observed aerosol events are given. A comparison with ground-based size distribution and chemical composition is performed. Hence the aim of this paper is to provide typical and statistically meaningful properties of Arctic aerosol, which may be used in climate models or to constrain the radiative forcing. We have found that the 2014 season was only moderately polluted with Arctic haze and that sea salt and sulphate were the most dominant aerosol species. Moreover the drying of an aerosol layer after cloud disintegration has been observed. Hardly any clear temporal evolution over the 4 week data set on Arctic haze is obvious with the exception of the extinction coefficient and the lidar ratio, which significantly decreased below 2 km altitude by end April. In altitudes between 2 and 5 km the haze season lasted longer and the aerosol properties were generally more homogeneous than closer to the surface. Above 5 km only few particles were found. The variability of the lidar ratio is discussed. It was found that knowledge of the aerosol’s size and shape does not determine the lidar ratio. Contrary to shape and lidar ratio, there is a clear correlation between size and backscatter: larger particles show a higher backscatter coefficient.

Description: This paper presents the results of measurements of aerosol physical and chemical properties during iAREA2014 campaign that took place on Svalbard between 15th of Mar and 4th of May 2014. With respect to field area, the experiment consisted of two sites: NyeÅlesund (78�550N, 11�560E) and Longyearbyen (78�130N, 15�330E) with further integration of Aerosol Robotic Network (AERONET) station in Hornsund (77�000N, 15�330E). The subject of this study is to investigate the inesitu, passive and active remote sensing observations as well as numerical simulations to describe the temporal variability of aerosol singleescattering properties during spring season on Spitsbergen. The retrieval of the data indicates several event days with enhanced singleescattering properties due to the existence of sulphate and additional seaesalt load in the atmosphere which is possibly caused by relatively high wind speed. Optical results were confirmed by numerical simulations made by the GEMeAQ model and by chemical observations that indicated up to 45% contribution of the seaesalt to a PM10 total aerosol mass concentration. An agreement between the in-situ optical and microphysical properties was found, namely: the positive correlation between aerosol scattering coefficient measured by the nephelometer and effective radius obtained from laser aerosol spectrometer as well as negative correlation between aerosol scattering coefficient and the Ångstrom exponent indicated that slightly larger particles dominated during special events. The inesitu surface observations do not show any significant enhancement of the absorption coefficient as well as the black carbon concentration which might occur during spring. All of extensive singleescattering properties indicate a diurnal cycle in Longyearbyen, where 21:00e5:00 data stays at the background level, however increasing during the day by the factor of 3e4. It is considered to be highly connected with local emissions originating in combustion, traffic and harbour activities. On the other hand, no daily fluctuations in NyeÅlesund are observed. Mean values in NyeÅlesund are equal to 8.2, 0.8 Mm�1 and 103 ng/m3 for scattering, absorption coefficients and black carbon concentration; however in Longyearbyen (only data from 21:00e05:00 UTC) they reach 7.9, 0.6 Mm�1 as well as 83 ng/ m3 respectively. Overall, the spring 2014 was considerably clean and seaesalt was the major aerosol component

Description: In this paper impact of intensive biomass burning (BB) in North America in July 2015, on aerosol optical and microphysical properties measured in the European Arctic is discussed. This study was made within the framework of the Impact of Absorbing Aerosols on radiating forcing in the European Arctic (iAREA) project. During the BB event aerosol optical depth (AOD) at 500 nm exceeded 1.2 in Spitsbergen and 0.7 in Andenes (Norway). Ångström Exponent (AE) exceeded 1.4 while the absorbing Ångström Exponent (AAE) varied between 1 and 1.25. BB aerosols were observed in humid atmosphere with a total water vapor column between 2 and 2.5 cm. In such conditions aerosols are activated and may produce clouds at different altitudes. Vertical structure of aerosol plumes over Svalbard, obtained from ceilometers and lidars, shows variability of range corrected signal between surface and middle and upper troposphere. Aerosol backscattering coefficients show values up to 10 -5m-1sr-1at 532 nm. Aerosol surface observations indicate chemical composition typical for biomass burning particles and very high single scattering properties. Scattering and absorption coefficients at 530 nm were up to 130 and 15 Mm-1, respectively. Single scattering albedo at the surface varied from 0.9 to 0.94. The averaged values over the entire atmospheric column, ranged from 0.93 to 0.99. Preliminary statistics of model and sunphotometer data as well as previous studies indicate that this event, in the Arctic region, must be considered extreme (such AOD was not observed in Svalbard since 2005) with a significant impact on energy budget.

Description: The aerosol studies during the ARctic EXperiment (AREX) campaigns were carried out onboard the r/v Oceania research ship between 1996 and 2004. During each campaign the r/v Oceania cruised for seven weeks (June-August) in the area of the Arctic between 0 and 14E and 69 and 79N. In 2002 the measurements were also carried out from the station in Ny-Ålesund on Spitsbergen in co-operation with the AWI team. The aerosol studies were conducted using an ensemble of instruments, including the FLS-12 lidar, laser particle counter CSASP-100-HV-SP, sun-photometers and ozonometer (Microtops II). The laser particle counter was placed on a mast of the vessel and moved vertically, which facilitated the determination of the vertical structure of aerosol concentrations and their size distribution at altitudes of up to 20 m a. s. l. Simultaneously lidar FLS-12 provided the vertical profiles of aerosol concentrations at altitudes of up to 500 m a. s. l. Those were further used for the calculation of aerosol optical thickness. During the measurements at the Ny-Ålesund Koldewey-Station of AWI, the Koldewey Aerosol Raman Lidar (KARL) was used to investigate the different aerosol scenarios. KARL is also regularly operated throughout the year, particularly during spring.

Description: 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 500 nm and 870 nm 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 þ0.003 at 500 nm, and between ␣0.004 and þ0.003 at 870 nm. 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 þ0.004 at 500 nm and between ␣0.002 and þ0.003 at 870 nm. RMSD and SDD values for Ångström exponent a 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.

Description: This book contributes to the current discussion on global environmental changes by discussing modifications in marine ecosystems related to global climate changes. In marine ecosystems, rising atmospheric CO2 and climate changes are associated with shifts in temperature, circulation, stratification, nutrient input, oxygen concentration and ocean acidification, which have significant biological effects on a regional and global scale. Knowing how these changes affect the distribution and abundance of plankton in the ocean currents is crucial to our understanding of how climate change impacts the marine environment. Ocean temperatures, weather and climatic changes greatly influence the amount and location of nutrients in the water column. If temperatures and currents change, the plankton production cycle may not coincide with the reproduction cycle of fish. The above changes are closely related to the changes in radiative forcing, which initiate feedback mechanisms like changes in surface temperature, circulation, and atmospheric chemistry.