Find in Library
Search millions of books, articles, and more
Indexed Open Access Databases
Lidar-Derived Aerosol Properties from Ny-Ålesund, Svalbard during the MOSAiC Spring 2020
oleh: Jonas Dube, Christine Böckmann, Christoph Ritter
Format: | Article |
---|---|
Diterbitkan: | MDPI AG 2022-05-01 |
Deskripsi
In this work, we present Raman lidar data (from a Nd:YAG operating at <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>355</mn><mspace width="0.166667em"></mspace></mrow></semantics></math></inline-formula> nm, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>532</mn><mspace width="0.166667em"></mspace></mrow></semantics></math></inline-formula> nm and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1064</mn><mspace width="0.166667em"></mspace></mrow></semantics></math></inline-formula> nm) from the international research village Ny-Ålesund for the time period of January to April 2020 during the <i>Arctic haze</i> season of the MOSAiC winter. We present values of the aerosol backscatter, the lidar ratio and the backscatter Ångström 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 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>532</mn><mspace width="0.166667em"></mspace></mrow></semantics></math></inline-formula> 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 ≈2500 m) the aerosol size distribution is quite constant in time, with dominance of small particles with a modal radius well below <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>100</mn><mspace width="0.166667em"></mspace></mrow></semantics></math></inline-formula> nm. On the contrary, below ≈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.