TY - GEN
T1 - Effect of sea breeze circulation on aerosol mixing state and radiative properties in the Negev Desert of Israel
AU - Derimian, Yevgeny
AU - Choël, Marie
AU - Rudich, Yinon
AU - Deboudt, Karine
AU - Dubovik, Oleg
AU - Laskin, Alexander
AU - Legrand, Michel
AU - Damiri, Bahaiddin
AU - Koren, Ilan
AU - Unga, Florin
AU - Moreau, Myriam
AU - Andreae, Meinrat O.
AU - Karnieli, Arnon
PY - 2018/4/1
Y1 - 2018/4/1
N2 - Chemical composition, microphysical and optical properties of
atmospheric aerosol deep inland in the Negev Desert of Israel are found
to be influenced by daily occurrences of sea breeze flow from the
Mediterranean Sea. Abrupt increases in aerosol volume concentration and
shifts of size distributions towards larger sizes, which are associated
with increase in wind speed and atmospheric water content, were
systematically recorded during the summertime at a distance of at least
80 km from the coast. Chemical imaging of aerosol samples showed an
increased contribution of highly hygroscopic particles during the
intrusion of the sea breeze. Besides a significant fraction of marine
aerosols, the amount of internally mixed marine and mineral dust
particles was also increased during the sea breeze period. The number
fraction of marine and internally mixed particles during the sea breeze
reached up to 88 % and 62 % in the 1-2.5 µm and 2.5-10 µm
size range, respectively. Additionally, numerous particles with
residuals of liquid coating were observed by SEM/EDX analysis. Ca-rich
dust particles that had reacted with anthropogenic nitrates were
evidenced by Raman microspectroscopy. The resulting hygroscopic
particles can deliquesce at very low relative humidity. Our observations
suggest that aerosol hygroscopic growth in the Negev Desert is induced
by the daily sea breeze arrival. The varying aerosol microphysical and
optical characteristics perturb the solar and thermal infrared
radiations. The changes in aerosol properties induced by the sea breeze,
relative to the background situation, doubled the shortwave radiative
cooling at the surface (from -10 to -20.5 Wm-2) and increased by almost
three times the warming of the atmosphere (from 5 to 14 Wm-2), as
evaluated for a case study. Given the large number of observed liquid
coating on individual particles, we also examined the possible influence
of the particle homogeneity assumption on the retrieval of aerosol
microphysical characteristics. Numerical simulations suggest that
sensitivity to the coating appears if backward scattering and
polarimetric measurements are available for the inversion algorithm.
This may have an important implication for retrievals of aerosol
microphysical properties in remote sensing applications.
AB - Chemical composition, microphysical and optical properties of
atmospheric aerosol deep inland in the Negev Desert of Israel are found
to be influenced by daily occurrences of sea breeze flow from the
Mediterranean Sea. Abrupt increases in aerosol volume concentration and
shifts of size distributions towards larger sizes, which are associated
with increase in wind speed and atmospheric water content, were
systematically recorded during the summertime at a distance of at least
80 km from the coast. Chemical imaging of aerosol samples showed an
increased contribution of highly hygroscopic particles during the
intrusion of the sea breeze. Besides a significant fraction of marine
aerosols, the amount of internally mixed marine and mineral dust
particles was also increased during the sea breeze period. The number
fraction of marine and internally mixed particles during the sea breeze
reached up to 88 % and 62 % in the 1-2.5 µm and 2.5-10 µm
size range, respectively. Additionally, numerous particles with
residuals of liquid coating were observed by SEM/EDX analysis. Ca-rich
dust particles that had reacted with anthropogenic nitrates were
evidenced by Raman microspectroscopy. The resulting hygroscopic
particles can deliquesce at very low relative humidity. Our observations
suggest that aerosol hygroscopic growth in the Negev Desert is induced
by the daily sea breeze arrival. The varying aerosol microphysical and
optical characteristics perturb the solar and thermal infrared
radiations. The changes in aerosol properties induced by the sea breeze,
relative to the background situation, doubled the shortwave radiative
cooling at the surface (from -10 to -20.5 Wm-2) and increased by almost
three times the warming of the atmosphere (from 5 to 14 Wm-2), as
evaluated for a case study. Given the large number of observed liquid
coating on individual particles, we also examined the possible influence
of the particle homogeneity assumption on the retrieval of aerosol
microphysical characteristics. Numerical simulations suggest that
sensitivity to the coating appears if backward scattering and
polarimetric measurements are available for the inversion algorithm.
This may have an important implication for retrievals of aerosol
microphysical properties in remote sensing applications.
M3 - Conference contribution
VL - 20
SP - 7867
BT - 20th EGU General Assembly, EGU2018, Proceedings from the conference held 4-13 April, 2018 in Vienna, Austria
CY - Vienna
ER -