2. AE 2 À AE 1
j
j ! 2
Difference between successive measurements as an absolute value during the same
day higher or equals 2. Chosen values are very unusual during the same day with
stable values of AOD.
3. AE mean À2AEi ! 2
Difference between mean value of the AOD and double variable value higher than
2. This condition selects outliers from the mean AE value.
4 Results and Discussion
Looking more closely in the data we distinguished those for which AOD exceed
0.1. Those data were used for the classification of events:
(1) AOD [ MEAN AOD þ STD AOD as an event
(2) AOD [ MEAN AOD þ 4STD AOD as an extreme event
Such analyses allowed for the specification of the occurrence of 5.27 % of events
in the entire data set. It gives a total of 8,326 out of 157,847 data rows. Extreme
events account for 2.35 % of the data (3,720 cases), and most of them occurred in
2003, 2006, 2008 and 2010.
While AOD gives information about the aerosol loading, the AE is elated to
aerosol size (type). The distribution of scatter plot enables to identify aerosol
sources and size distribution (Toledano 2007). For that purpose we have prepared a
scatter plot of AOD versus AE with information of number of measurements.
Aerosols can be divided into the following types:
1. Marine aerosols
The pure marine should be located in the region with AOD < 0.15 and AE 0.5–1.7.
This type is confined to the so-called accumulation mode and is present above the
oceanic areas. The potential transport of continental aerosols over maritime environments interferences with this type of particles, which changes density and
particle size distribution.
2. Continental and biomass burning aerosols
Continental origin aerosols are also expected at coastal sites. This type mainly
consists of fine particles (<2.5 μm), and presents high values of AE (above 1). The
AOD is very variable and depends on the weather conditions (mostly around 0.15–
0.30), and that aerosols could be less or more polluted (AOD > 2.5 during e.g.
forest fires etc.). Biomass burning aerosols are characterized by turbid atmosphere
and large values of the AOD are reported.
30
P. Pakszys et al.
j
j ! 2
Difference between successive measurements as an absolute value during the same
day higher or equals 2. Chosen values are very unusual during the same day with
stable values of AOD.
3. AE mean À2AEi ! 2
Difference between mean value of the AOD and double variable value higher than
2. This condition selects outliers from the mean AE value.
4 Results and Discussion
Looking more closely in the data we distinguished those for which AOD exceed
0.1. Those data were used for the classification of events:
(1) AOD [ MEAN AOD þ STD AOD as an event
(2) AOD [ MEAN AOD þ 4STD AOD as an extreme event
Such analyses allowed for the specification of the occurrence of 5.27 % of events
in the entire data set. It gives a total of 8,326 out of 157,847 data rows. Extreme
events account for 2.35 % of the data (3,720 cases), and most of them occurred in
2003, 2006, 2008 and 2010.
While AOD gives information about the aerosol loading, the AE is elated to
aerosol size (type). The distribution of scatter plot enables to identify aerosol
sources and size distribution (Toledano 2007). For that purpose we have prepared a
scatter plot of AOD versus AE with information of number of measurements.
Aerosols can be divided into the following types:
1. Marine aerosols
The pure marine should be located in the region with AOD < 0.15 and AE 0.5–1.7.
This type is confined to the so-called accumulation mode and is present above the
oceanic areas. The potential transport of continental aerosols over maritime environments interferences with this type of particles, which changes density and
particle size distribution.
2. Continental and biomass burning aerosols
Continental origin aerosols are also expected at coastal sites. This type mainly
consists of fine particles (<2.5 μm), and presents high values of AE (above 1). The
AOD is very variable and depends on the weather conditions (mostly around 0.15–
0.30), and that aerosols could be less or more polluted (AOD > 2.5 during e.g.
forest fires etc.). Biomass burning aerosols are characterized by turbid atmosphere
and large values of the AOD are reported.
30
P. Pakszys et al.