@article{DubeBoeckmannRitter2022,
  author    = {Dube, Jonas and B{\"o}ckmann, Christine and Ritter, Christoph},
  title     = {Lidar-Derived Aerosol Properties from Ny-{\AA}lesund, Svalbard during the MOSAiC Spring 2020},
  series = {Remote sensing / Molecular Diversity Preservation International (MDPI)},
  volume    = {14},
  journal   = {Remote sensing / Molecular Diversity Preservation International (MDPI)},
  number    = {11},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2072-4292},
  doi       = {10.3390/rs14112578},
  pages     = {17},
  year      = {2022},
  abstract  = {In this work, we present Raman lidar data (from a Nd:YAG operating at 355 nm, 532 nm and 1064 nm) from the international research village Ny-Alesund for the time period of January to April 2020 during the Arctic haze season of the MOSAiC winter. We present values of the aerosol backscatter, the lidar ratio and the backscatter Angstrom exponent, though the latter depends on wavelength. The aerosol polarization was generally below 2\%, indicating mostly spherical particles. We observed that events with high backscatter and high lidar ratio did not coincide. In fact, the highest lidar ratios (LR > 75 sr at 532 nm) were already found by January and may have been caused by hygroscopic growth, rather than by advection of more continental aerosol. Further, we performed an inversion of the lidar data to retrieve a refractive index and a size distribution of the aerosol. Our results suggest that in the free troposphere (above approximate to 2500 m) the aerosol size distribution is quite constant in time, with dominance of small particles with a modal radius well below 100 nm. On the contrary, below approximate to 2000 m in altitude, we frequently found gradients in aerosol backscatter and even size distribution, sometimes in accordance with gradients of wind speed, humidity or elevated temperature inversions, as if the aerosol was strongly modified by vertical displacement in what we call the "mechanical boundary layer". Finally, we present an indication that additional meteorological soundings during MOSAiC campaign did not necessarily improve the fidelity of air backtrajectories.},
  language  = {en}
}
@article{RitterAngelesBurgosBoeckmannetal.2018,
  author    = {Ritter, Christoph and {\´A}ngeles Burgos, Mar{\´i}a and B{\"o}ckmann, Christine and Mateos, David and Lisok, Justyna and Markowicz, Krzysztof M. and Moroni, Beatrice and Cappelletti, David and Udisti, Roberto and Maturilli, Marion and Neuber, Roland},
  title     = {Microphysical properties and radiative impact of an intense biomass burning aerosol event measured over Ny-angstrom lesund, Spitsbergen in July 2015},
  series = {Tellus - Series B, Chemical and Physical Meteorology},
  volume    = {70},
  journal   = {Tellus - Series B, Chemical and Physical Meteorology},
  publisher = {Routledge, Taylor \& Francis Group},
  address   = {Abingdon},
  issn      = {1600-0889},
  doi       = {10.1080/16000889.2018.1539618},
  pages     = {23},
  year      = {2018},
  abstract  = {In this work, an evaluation of an intense biomass burning event observed over Ny-angstrom lesund (Spitsbergen, European Arctic) in July 2015 is presented. Data from the multi-wavelengths Raman-lidar KARL, a sun photometer and radiosonde measurements are used to derive some microphysical properties of the biomass burning aerosol as size distribution, refractive index and single scattering albedo at different relative humidities. Predominantly particles in the accumulation mode have been found with a bi-modal distribution and dominance of the smaller mode. Above 80\% relative humidity, hygroscopic growth in terms of an increase of particle diameter and a slight decrease of the index of refraction (real and imaginary part) has been found. Values of the single scattering albedo around 0.9 both at 355nm and 532nm indicate some absorption by the aerosol. Values of the lidar ratio are around 26sr for 355nm and around 50sr for 532nm, almost independent of the relative humidity. Further, data from the photometer and surface radiation values from the local baseline surface radiation network (BSRN) have been applied to derive the radiative impact of the biomass burning event purely from observational data by comparison with a clear background day. We found a strong cooling for the visible radiation and a slight warming in the infra-red. The net aerosol forcing, derived by comparison with a clear background day purely from observational data, obtained a value of -95 W/m(2) per unit AOD500.},
  language  = {en}
}