P. Pakszys

Impact of North American intense fires on aerosol optical properties measured over the European Arctic in July 2015

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). Angstrom Exponent (AE) exceeded 1.4 while the absorbing Angstrom 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.

Annual changes of aerosol optical depth and Ångström exponent over Spitsbergen

In this work we present the annual changes of two major, climate related aerosol optical parameters measured at three Spitsbergen locations, Ny-Alesund, Longyearbyen and Hornsund over a period between 2000 and 2012. We discuss the changes of aerosol optical depth (AOD) at 500 nm and the Angstrom exponent (AE) (440–870 nm) measured with use of different types of sun photometers. For the measurement data we adopted several data quality assurance techniques and the calibration of the instruments was taken into consideration. The results obtained show that marine source has been a dominating of aerosol sources over Spitsbergen. Some years (2005, 2006, 2008 and 2011) show very high values of AOD due to strong aerosol events such as the Arctic Haze. In general the mean AOD values increase over the period of 2000 and 2012 over Spitsbergen. This may indicate the presence of larger scale of atmospheric pollution in the region.

A Modern Approach to Aerosol Studies Over the Baltic Sea

Aerosols measured in coastal areas are significantly different from those over an open sea, both in terms of structure and physical properties. The aerosol composition and concentrations are generally uniform in the open sea area. In the case of coastal areas, the composition may be changed within a short period of time. Aerosols in coastal zone can be divided into three groups: the sea, a mixture of continental and maritime, and continental. This chapter describes the most representative day of a research campaign designed to characterize the optical properties of aerosols in the Baltic Sea (open sea and coastal areas). During the campaign, simultaneous measurements of aerosol optical depth were carried out at four stations around the Baltic Sea—Bornholm, Sopot, Preila and Liepaja, using the hand-held Microtops II sun photometers. The studies were supplemented with satellite data (MODIS) and the analysis of air mass back-trajectories at various altitudes and wind fields. Measurements were performed at four stations. Simultaneous measurements at these stations with use of Microtops sun photometer can provide important information on the aerosol optical depth (AOD) and hence on the radiation balance. Data obtained with Microtops complement well with those obtained from MODIS. Using wind field profiles we possibly detected sea surface impact on aerosol concentrations in Bornholm, where on 3 August 2011 the AOD was significantly greater, along with a strong onshore winds.

Impact of Breaking Waves on Sea Salt Production and Local Change of Aerosol Optical Properties

In this paper we discuss local impact of breaking waves on production of sea salt aerosols and hence on the change of aerosol size distribution and particle optical properties. Our studies were made between 17 and 27 July 2012 at the Coastal Research Station (CRS) in Lubiatowo on the Polish Baltic coast. During the studies aerosol optical depth was measured using Microtops II sun photometers and AERONET and MODIS data were used to support the further analyses. We show that with the local wave breaking phenomenon the aerosol optical depth may increase by a magnitude of even one order and that the ensemble of aerosol particles may shift from the dominating fine mode to coarse mode (sea salt). Such shift may have a strong local impact on the radiative forcing and hence on a local climate.

Application of an Object Classification Method for Determining the Spatial Distribution of Sea Bottom Structures and Their Cover Using Images from a Side Scan Sonar

Side Scan Sonars combined to positioning systems constitute an exceptionally valuable tool for collecting information about seabed characteristics. The main objective of this study is to apply the new methods of object classification, based on Side Scan Sonar images for determining the bottom structure and coverage. The aim is to adapt land image analysis for acoustic data and to produce a reliable model that can be applied in further analysis. Software development tailored for this type of data enables wide-range analysis and visualization of spatial data. The main tool used in postprocessing of sonar images was the Trimble eCognition™ Developer. The classification process is a categorization of objects and phenomena in the analyzed area. Classification uses information contained in a single pixel creating more general scheme. An automated mode of the classification method is used in this study OBIA (Object-Based Image Analysis). Classification is based on the segmentation process, in which pixels are divided into homogeneous regions with respect to neighboring pixels, which determines the final shape of each class object. Objects and parameters, controlling the processing of supervised classification, are selected by user. Representative functions of every object are defined by the user to depict each class, helping to assign them to specific classes. The adopted approach for mixed type of classification processes, is based on the reference objects and training samples and subsequently classifies them by class discriminants. As a result a sonar mosaic map of the seabed image classes is provided in relationship to the bottom sediments and the bottom surface roughness. The presented results could help to transform a protected area HELCOM BSPA into the undersea sanctuary in the Gulf of Gdansk (Baltic Sea) and support this very important interdisciplinary environmental study. In this paper, I have demonstrated that a multistage image segmentation methodology can be more efficiently used for geomorphometry and terrain classification for underwater areas obtained from a side scan sonar mosaic. The methodology introduced in this paper can be applied for many other applications where relationships between topographic features and other components are to be assessed (samples etc.). In this way, we hope to address a time-consuming task to produce underwater maps with bigger scales but still with an appropriate resolution.