9 research outputs found
The Umov effect for large irregular-shaped particles
Results of studying the Umov effect for nonspherical particles large as compared to the incident radiation wavelength are presented. The study is carried out for particles with the maximum size of 100, 140, 170, and 200 Ī¼m. The results have been obtained for 210 different refractive indices whose real part varied from 1.3 to 1.6 with a step of 0.5 and the imaginary part varied within the range from 0 to 0.1344. It has been found that the Umov effect occurs for all abovementioned particles provided that the imaginary part of the refractive index is less than 0.00
On measurements of aerosol-gas composition of the atmosphere during two expeditions in 2013 along the Northern Sea Route
We presented the results of expedition measurements of the set of
physical-chemical characteristics of atmospheric aerosol in
areas of the Arctic and Far East seas, performed onboard RV
<i>Akademik Fedorov</i> (17 Augustā22 September 2013) and RV
<i>Professor Khljustin</i> (24 Julyā7 September 2013). The specific
features of spatial distribution and time variations of aerosol optical depth
(AOD) of the atmosphere in the wavelength range of 0.34ā2.14 Ī¼m
and boundary layer height, aerosol and black carbon mass concentrations, and
disperse and chemical composition of aerosol are discussed. Over the Arctic
Ocean (on the route of RV <i>Akademik Fedorov</i>) there is a decrease in
aerosol and black carbon concentrations in a northeastern direction: higher
values were observed in the region of Spitsbergen and near the Kola
Peninsula; and minimum values were observed at northern margins of the Laptev
Sea. Average AOD (0.5 Ī¼m) values in this remote region were 0.03;
the aerosol and black carbon mass concentrations were 875 and
22 ng m<sup>ā3</sup>, respectively. The spatial distributions of most aerosol
characteristics over Far East seas show their latitudinal decrease in the
northern direction. On transit of RV <i>Professor Khljustin</i> from the
Japan Sea to the Chukchi Sea, the aerosol number concentration decreased on
average from 23.7 to 2.5 cm<sup>ā3</sup>, the black carbon mass concentration
decreased from 150 to 50 ng m<sup>ā3</sup>, and AOD decreased from 0.19 to 0.03.
We analyzed the variations in the boundary layer height, measured by
ship-based lidar: the average value was 520 m, and the maximal value was
1200 m. In latitudinal distribution of the boundary layer height, there is a
characteristic minimum at a latitude of ~ 55Ā° N. For water
basins of eight seas, we present the chemical compositions of the
water-soluble aerosol fraction (ions, elements) and small gas-phase species,
as well as estimates of their vertical fluxes. It is shown that substances
are mainly (75ā89 %) supplied from the atmosphere to the sea surface
together with gas-phase species. The deposited ions account for from 11 to
24.5 %, and trace elements account for 0.2ā0.4 % of the total sum of
water-soluble components. The average vertical fluxes of aerosol substance
are a factor of 4ā7 larger in the Japan Sea than in the water basins of
Arctic seas