Lidar observations of long-range transported Saharan dust over Sofia, Bulgaria: a case study of dust mixed with local aerosols

Abstract

.Two-wavelength (1064/532 nm) lidar observations of long-range transported Saharan dust present in the atmosphere over Sofia, Bulgaria, during a 4-day dust intrusion event in winter 2010, are reported. Aged desert aerosols are detected at altitudes up to 4 km above the sea level, within and above the boundary layer as mixed with other aerosols—representing the particular case under consideration. Optical, microphysical, and dynamical properties of dust aerosols are obtained and analyzed. Special attention is paid to retrieving and vertical profiling of dust backscatter-related Ångström exponents (BAEs), as well as to determining their frequency-count distributions. Obtained BAE values in the range 0.3 to 0.6 (±0.2) indicate domination of coarse particles in the near overmicron size range. Reasonability of coarse-mode-dominated dust size composition is substantiated, based on measurement and transportation-history analysis. The performed frequency-count statistics reveals dust BAE distributions asymmetrically extended to multimode distribution shapes, resulting from dust mixing with finer local aerosol fractions. Peculiarities and patterns of the aerosol dynamics at different stages of dust-loading event are revealed and discussed.

Lidar study of unusual winter Saharan dust loads above Sofia, Bulgaria: impacts on the local weather and troposphere

“…The wintertime Saharan dust events presented and discussed were studied by means of an aerosol lidar designed and built in the LRL. 8,12,43 The lidar system is configured in a mono-static biaxial alignment pointing at an angle of 32 deg with respect to the horizon, as determined by its position in the lab. Therefore, although signals from as far as 30 km can be recorded, the maximum sounding height is limited to about 16 km.…”

“…3 Huge amounts of airborne desert dust are frequently transported north-eastward to the Mediterranean and Europe each year. [4][5][6][7][8][9][10][11][12][13] Intrusions of Saharan dust over Europe mostly take place in spring and summer, as observations by ground-based and air/space-born apparatus have shown. In winter, the European continent is predominantly invaded by cold frontal systems from the north; therefore, events of desert dust transport are less probable and, as a rule, rare.…”

“…[5][6][7]10 However, cases of the presence of Saharan dust in the atmosphere above Europe in winter months have multiplied, as proven by satellite, in situ, and lidar observations conducted during the last several years. 8,11,[14][15][16][17][18][19][20][21][22] The massive load of desert dust into the atmosphere and its subsequent long-range transport over vast geographic areas has various and strong effects on the global and regional climate, atmospheric conditions, processes, and air circulations, as well as on ecosystems and human health. 1,[23][24][25][26][27][28] Furthermore, when the events of atmospheric mineral dust intrusions at middle and high latitudes take place during the winter season, these effects have more specific and much stronger manifestations.…”

“…Lidars are efficient and widely adopted instruments for conducting observations of atmospheric aerosol pollutants, including desert dust. [6][7][8][9]12,17,18,29,30 They enable real-time measurements and assessments of atmospheric aerosols, establishing their optical, topological, and dynamical parameters over broad areas with high spatial and temporal resolution. Furthermore, the microphysical properties of mineral dust particles can also be determined and characterized qualitatively or quasi-quantitatively in terms of Ångström exponent [31][32][33] evaluation and profiling by making use of two-or multi-wavelength lidars.…”

Detection of a Dust Storm in 2020 by a Multi-Observation Platform over the Northwest China

“…Due to the fact that lightscattering characteristics of aerosol particles were altered after up-taking water vapor, Tong Wu et al [32] studied the aerosol hygroscopic growth from micropulse Lidar. A long-range transported Saharan dust over Sofia, Bulgaria was detected by two-wavelength (1064/532 nm) Lidar including the optical, microphysical, and dynamical properties of dust aerosols at different stages [33]. The results shown that the dust backscatter-related Angstrom exponents (BAEs) values were in the range of 0.3 to 0.6 (±0.2), which indicated domination of coarse particles in the micron size range.…”