A Comparative Case Analysis of Meteorological and Air Pollution Parameters between a High and Low Port Activity Period in Igoumenitsa Port †

: Among the most important trade bridges for Western Europe and the Balkans is the Port of Igoumenitsa in Western Greece, which experiences heavy trafﬁc of goods and passengers. This case analysis primarily aims to investigate the effect of shipping and port operations on air quality in the Port of Igoumenitsa, comparing two representative short case seasons of air quality measurement campaigns. The high activity season ranges from 25 to 31 August 2018, while the low season ranges from 17 to 25 May 2018. A mobile air quality monitoring system was used to perform the analysis. To compare the air quality of the examined periods, the wind speed rose diagrams, the correlation analysis, as well as the hourly variations in concentrations of pollutants and meteorological parameters, were studied. In addition, the impact of meteorology and atmospheric circulation on local air quality were investigated. For study implementation, various types of data, obtained from NASA Worldview application, Barcelona Supercomputing Center (BSC), and Giovanni online system (NASA-GES-DISC) were included. The results indicate that port operations affect the air quality in the Port of Igoumenitsa, as the high season showed higher concentrations of air pollutants compared to the low season. A notable exception was the concentration of PMs, which was affected by an African dust transfer event during the low season. Finally, the ﬁndings indicate that climatic factors affect the pollution levels of the case analysis, and emphasize the importance of developing a green and sustainable management system within the port.


Introduction
The port activities and shipping are a major source of pollutants for the coastal areas, affecting not only air quality and its degradation [1,2] but also human health [3,4]. Although the port-related pollutants are not the dominant source of marine pollution, they are related to health problems and have an impact on mortality levels [5,6]. In particular, it turns out that human health problems are associated with exposure to PM 2.5 emitted by shipping [1,7]. Evidently, emissions from shipping contribute significantly to the NO x , SO 2 , and PM concentrations over port and coastal regions, while between 2007 and 2012, shipping accounted for about 1 billion tons of GHGs [8]. The IMO's 4th Greenhouse Gas Study [9] projected that the GHGs shipping emissions will increase up to 50% by 2050 compared to the 2018 levels. Consequently, increasing shipping and port activities contribute to climate change [10]. In particular, the increased concentration of pollutants in the atmosphere affects the weather and climate [11], producing positive climate forcing and enhancing the climate risk.
The atmospheric circulation is also a significant factor that affects the air quality [2,7]. The transfer and transformation of pollutants from Europe as well as the mineral dust from North Africa affect the pollution levels of the southeastern Mediterranean [12]. In particular, the peak of dust transfer is usually identified during the autumn and spring season affecting the concentration of PMs [13]. Finally, dust episodes have an impact on the climate since they modify the albedo and solar radiation on the earth's surface [12].
The port of Igoumenitsa is an important trade hub between Western and Eastern Europe, which connects the main Italian ports with Western Greece. About 1.5 million passengers and 140,000 trucks move through the port each year. Based on the lack of studies regarding the effect of shipping and atmospheric features (meteorology and synoptic atmospheric circulation) on the air quality in Western Greece, this analysis seeks to fill this gap. A comparison of the two seasons is characterized by the high and low port activity, respectively. Finally, this study highlights the importance of a larger measurement campaign in order to further improve the knowledge regarding the impact of shipping on the coastal port region of Igoumenitsa.

Methods and Data
Igoumenitsa (39.50615 • N, 20.265534 • E) is located in Western Greece ( Figure 1) and it is a commercial hub for Southeastern Europe. The port of the city has high trade activity as a large number of passengers, cars, and trucks use it on an annual basis. A mobile air quality monitoring station, equipped with ambient air pollution sensors (HORIBA sensors) and in accordance with the EN regulations for certified measurements, was employed at the port of Igoumenitsa. Sensor recordings include meteorological parameters (wind direction-WDir; • , wind speed-WS; m/s, temperature-T; • C, relative humidity; RH-%, pressure-P; hPa), particle matters (PM 1 , PM 2.5 , PM 4 , PM 10 , PM_ tot ; µg/m 3 ), and gases (CO; ppm, NO; ppb, NO 2 ; ppb, NO x ; ppb, O 3 ; ppb, SO 2 ; ppb). compared to the 2018 levels. Consequently, increasing shipping and port activities contribute to climate change [10]. In particular, the increased concentration of pollutants in the atmosphere affects the weather and climate [11], producing positive climate forcing and enhancing the climate risk. The atmospheric circulation is also a significant factor that affects the air quality [2,7]. The transfer and transformation of pollutants from Europe as well as the mineral dust from North Africa affect the pollution levels of the southeastern Mediterranean [12]. In particular, the peak of dust transfer is usually identified during the autumn and spring season affecting the concentration of PMs [13]. Finally, dust episodes have an impact on the climate since they modify the albedo and solar radiation on the earth's surface [12].
The port of Igoumenitsa is an important trade hub between Western and Eastern Europe, which connects the main Italian ports with Western Greece. About 1.5 million passengers and 140,000 trucks move through the port each year. Based on the lack of studies regarding the effect of shipping and atmospheric features (meteorology and synoptic atmospheric circulation) on the air quality in Western Greece, this analysis seeks to fill this gap. A comparison of the two seasons is characterized by the high and low port activity, respectively. Finally, this study highlights the importance of a larger measurement campaign in order to further improve the knowledge regarding the impact of shipping on the coastal port region of Igoumenitsa.

Methods and Data
Igoumenitsa (39.50615° Ν, 20.265534° Ε) is located in Western Greece ( Figure 1) and it is a commercial hub for Southeastern Europe. The port of the city has high trade activity as a large number of passengers, cars, and trucks use it on an annual basis. A mobile air quality monitoring station, equipped with ambient air pollution sensors (HORIBA sensors) and in accordance with the EN regulations for certified measurements, was employed at the port of Igoumenitsa. Sensor recordings include meteorological parameters (wind direction-WDir; °, wind speed-WS; m/s, temperature-T; °C, relative humidity; RH-%, pressure-P; hPa), particle matters (PM1, PM2.5, PM4, PM10, PM_tot; μg/m 3 ), and gases (CO; ppm, NO; ppb, NO2; ppb, NOx; ppb, O3; ppb, SO2; ppb). To study the impact of harbor operation in the port of Igoumenitsa during 2018, two cases were examined. The first case, with high port activity (HS), is considered the period from 25 to 31 August 2018, and the second, with low port activity (LS), is from 17 to 25 May 2018. In order to investigate the relation between the meteorology and concentration of pollutants, the Spearman correlation is employed for both studied seasons. Moreover, the hourly variation of meteorology parameters and concentration of pollutants are calculated to study the effect of hourly port activity during the two seasons. To examine the effect of synoptic atmospheric circulation on concentrations of PMs in the port, a satellite image provided by NASA Worldview application is also used ( Figure 2a). Additionally, a figure provided by the DREAM8b model, operated by the Barcelona Supercomputing Center, is shown ( Figure 2b). Results from MERRA-2 model version 2 (M2T1NXAER v5.12.4), available from the Giovanni online data system generated by NASA Goddard Earth Sciences (GES) Data and Information Services Center (DISC) [14], are also included To study the impact of harbor operation in the port of Igoumenitsa during 2018, two cases were examined. The first case, with high port activity (HS), is considered the period from 25 to 31 August 2018, and the second, with low port activity (LS), is from 17 to 25 May 2018. In order to investigate the relation between the meteorology and concentration of pollutants, the Spearman correlation is employed for both studied seasons. Moreover, the hourly variation of meteorology parameters and concentration of pollutants are calculated to study the effect of hourly port activity during the two seasons. To examine the effect of synoptic atmospheric circulation on concentrations of PMs in the port, a satellite image provided by NASA Worldview application is also used ( Figure 2a). Additionally, a figure provided by the DREAM8b model, operated by the Barcelona Supercomputing Center, is shown ( Figure 2b). Results from MERRA-2 model version 2 (M2T1NXAER v5.12.4), available from the Giovanni online data system generated by NASA Goddard Earth Sciences (GES) Data and Information Services Center (DISC) [14], are also included in the analysis. Finally, the PM 2.5 /PM 10 ratio (R PM ) is usually used to characterize the origin of pollutants (the anthropogenic or natural sources) [2,15]. In order to investigate the impact of shipping traffic and port operations (anthropogenic activities) in the port of Igoumenitsa, the R PM is calculated for both case seasons (HS and LS). in the analysis. Finally, the PM2.5/PM10 ratio ( ) is usually used to characterize the origin of pollutants (the anthropogenic or natural sources) [2,15]. In order to investigate the impact of shipping traffic and port operations (anthropogenic activities) in the port of Igoumenitsa, the is calculated for both case seasons (HS and LS).  Figure 3 shows the wind-rose plot for the two studied periods, where the wind speeds are stronger in the LS (compared to HS) and blow mainly from the western sector, as well as the eastern directions for the HS and LS, respectively. The relation (negative correlation) of the wind speed with the concentration of pollutants indicates that higher winds tend to reduce the concentration for the majority of pollutants (PM10, PMtot, CO, NO2, and NOx). The wind speed is positively correlated with the O3 concentration since the O3 concentration is affected by photochemical reactions during the sunlight hours [11]. Additionally, the concentration of O3 is significantly negatively correlated (about −0.65) with NO2 and NOx. To conclude, the analysis shows that meteorological conditions significantly affect the air quality [16,17]. Figure 4 shows the hourly variation of meteorology parameters (Figure 4a-e) and the concentration of pollutants (Figure 4f-p) for both studied seasons. The analysis shows that the concentration of pollutants is maximized during the hours with high ship traffic (7:00-11:00 LT and 19:00-24:00 LT) indicating that harbor operations degrade the air quality in the port of Igoumenitsa. Comparing the two seasons studied, the O3 and NOx concentrations increased by about 10 ppb for HS. Additionally, the concentrations of NO2 and SO2 are increased ~2.5 ppb for the HS in comparison to the LS. Moreover, during the HS, the concentration of PM1 is increased ~2.5 μg/m 3 , while in contrast, the concentration of PM4, as well as PM10, is reduced ~5.5 μg/m 3 . The positive difference of PM4 and PM10, between HS and LS, is explained by the synoptic atmospheric circulation. In particular, it must be  Figure 3 shows the wind-rose plot for the two studied periods, where the wind speeds are stronger in the LS (compared to HS) and blow mainly from the western sector, as well as the eastern directions for the HS and LS, respectively. in the analysis. Finally, the PM2.5/PM10 ratio ( ) is usually used to characterize the origin of pollutants (the anthropogenic or natural sources) [2,15]. In order to investigate the impact of shipping traffic and port operations (anthropogenic activities) in the port of Igoumenitsa, the is calculated for both case seasons (HS and LS).  Figure 3 shows the wind-rose plot for the two studied periods, where the wind speeds are stronger in the LS (compared to HS) and blow mainly from the western sector, as well as the eastern directions for the HS and LS, respectively. The relation (negative correlation) of the wind speed with the concentration of pollutants indicates that higher winds tend to reduce the concentration for the majority of pollutants (PM10, PMtot, CO, NO2, and NOx). The wind speed is positively correlated with the O3 concentration since the O3 concentration is affected by photochemical reactions during the sunlight hours [11]. Additionally, the concentration of O3 is significantly negatively correlated (about −0.65) with NO2 and NOx. To conclude, the analysis shows that meteorological conditions significantly affect the air quality [16,17]. Figure 4 shows the hourly variation of meteorology parameters (Figure 4a-e) and the concentration of pollutants (Figure 4f-p) for both studied seasons. The analysis shows that the concentration of pollutants is maximized during the hours with high ship traffic (7:00-11:00 LT and 19:00-24:00 LT) indicating that harbor operations degrade the air quality in the port of Igoumenitsa. Comparing the two seasons studied, the O3 and NOx concentrations increased by about 10 ppb for HS. Additionally, the concentrations of NO2 and SO2 are increased ~2.5 ppb for the HS in comparison to the LS. Moreover, during the HS, the concentration of PM1 is increased ~2.5 μg/m 3 , while in contrast, the concentration of PM4, as well as PM10, is reduced ~5.5 μg/m 3 . The positive difference of PM4 and PM10, between HS and LS, is explained by the synoptic atmospheric circulation. In particular, it must be The relation (negative correlation) of the wind speed with the concentration of pollutants indicates that higher winds tend to reduce the concentration for the majority of pollutants (PM 10 , PM tot , CO, NO 2 , and NO x ). The wind speed is positively correlated with the O3 concentration since the O3 concentration is affected by photochemical reactions during the sunlight hours [11]. Additionally, the concentration of O3 is significantly negatively correlated (about −0.65) with NO 2 and NO x . To conclude, the analysis shows that meteorological conditions significantly affect the air quality [16,17]. Figure 4 shows the hourly variation of meteorology parameters (Figure 4a-e) and the concentration of pollutants (Figure 4f-p) for both studied seasons. The analysis shows that the concentration of pollutants is maximized during the hours with high ship traffic (7:00-11:00 LT and 19:00-24:00 LT) indicating that harbor operations degrade the air quality in the port of Igoumenitsa. Comparing the two seasons studied, the O 3 and NO x concentrations increased by about 10 ppb for HS. Additionally, the concentrations of NO 2 and SO 2 are increased~2.5 ppb for the HS in comparison to the LS. Moreover, during the HS, the concentration of PM 1 is increased~2.5 µg/m 3 , while in contrast, the concentration of PM 4 , as well as PM 10 , is reduced~5.5 µg/m 3 . The positive difference of PM 4 and PM 10 , between HS and LS, is explained by the synoptic atmospheric circulation. In particular, it must be stated that the Saharan dust is a major component for PM 10 over the Mediterranean basin [18]. Previous studies have shown that the concentration of PM 10 is maximized mainly during the transitional seasons (autumn and spring) [19]. In particular, for the Heraklion and Athens (Greece), the concentration of PM 10 is maximized in April during 2003-2006, which is possible due to the dust transport [12,13]. During the low port activity season, the African dust transfer event affects the eastern Mediterranean and the Western Greece and peaks on 23 May 2018 (Figure 2a,b). Furthermore, the results of the analysis of MERRA-2 model (available from the Giovanni data system) indicate that during the LS the difference of mean dust column mass density (gr/m 2 ) increases compared to the high season, affecting the PM concentrations (mainly PM 10 and PM 4 ) over Western Greece and the port of Igoumenitsa ( Figure 5).

Results
Eng. Proc. 2022, 4, x FOR PEER REVIEW 4 of 6 stated that the Saharan dust is a major component for PM10 over the Mediterranean basin [18]. Previous studies have shown that the concentration of PM10 is maximized mainly during the transitional seasons (autumn and spring) [19]. In particular, for the Heraklion and Athens (Greece), the concentration of PM10 is maximized in April during 2003-2006, which is possible due to the dust transport [12,13]. During the low port activity season, the African dust transfer event affects the eastern Mediterranean and the Western Greece and peaks on 23 May 2018 (Figure 2a,b). Furthermore, the results of the analysis of MERRA-2 model (available from the Giovanni data system) indicate that during the LS the difference of mean dust column mass density (gr/m 2 ) increases compared to the high season, affecting the PM concentrations (mainly PM10 and PM4) over Western Greece and the port of Igoumenitsa ( Figure 5). In general, human activities and meteorological conditions are important factors that affect the ratio between PM2.5 and PM10 ( ) [15]. The higher (lower) is more related to anthropogenic (natural) sources [15]. Additionally, the can be used to identify the source of the PMs, indicating whether the pollution is primarily due to anthropogenic or natural activity [2,20]. In order to investigate the impact of harbor operation on Igoumenitsa port, the is calculated. Figure 6 presents the variability of for the two studied seasons. During the HS, the ratio is about 0.13 higher compared to the LS (Figure 6c). Consequently, during the HS, the shipping has a more significant effect on the pollution levels of Igoumenitsa. which is possible due to the dust transport [12,13]. During the low port activity season, the African dust transfer event affects the eastern Mediterranean and the Western Greece and peaks on 23 May 2018 (Figure 2a,b). Furthermore, the results of the analysis of MERRA-2 model (available from the Giovanni data system) indicate that during the LS the difference of mean dust column mass density (gr/m 2 ) increases compared to the high season, affecting the PM concentrations (mainly PM10 and PM4) over Western Greece and the port of Igoumenitsa ( Figure 5). In general, human activities and meteorological conditions are important factors that affect the ratio between PM2.5 and PM10 ( ) [15]. The higher (lower) is more related to anthropogenic (natural) sources [15]. Additionally, the can be used to identify the source of the PMs, indicating whether the pollution is primarily due to anthropogenic or natural activity [2,20]. In order to investigate the impact of harbor operation on Igoumenitsa port, the is calculated. Figure 6 presents the variability of for the two studied seasons. During the HS, the ratio is about 0.13 higher compared to the LS (Figure 6c). Consequently, during the HS, the shipping has a more significant effect on the pollution levels of Igoumenitsa. In general, human activities and meteorological conditions are important factors that affect the ratio between PM 2.5 and PM 10 (R PM ) [15]. The higher (lower) R PM is more related to anthropogenic (natural) sources [15]. Additionally, the R PM can be used to identify the source of the PMs, indicating whether the pollution is primarily due to anthropogenic or natural activity [2,20]. In order to investigate the impact of harbor operation on Igoumenitsa port, the R PM is calculated. Figure 6 presents the variability of R PM for the two studied seasons. During the HS, the R PM ratio is about 0.13 higher compared to the LS (Figure 6c). Consequently, during the HS, the shipping has a more significant effect on the pollution levels of Igoumenitsa.
Eng. Proc. 2022, 4, x FOR PEER REVIEW 5 of 6 Figure 5. Composite difference of mean dust column mass density (gr/m 2 ) between the low port activity and high port activity season. Red/blue colors indicate an increase/decrease of the mean dust column mass density (gr/m 2 ).

Conclusions
This work examines the effect of shipping and port operation on the pollution levels of Igoumenitsa in Western Greece. The analysis is carried out through a comparison of the high (HS) and low (LS) port activity season during 2018 and the obtained findings indicate that meteorology affects the concentration of pollutants. In particular, wind speed tends to reduce the concentration of the majority of pollutants. For both seasons, the elevated concentration of pollutants occurs during the hours of high shipping traffic. It should be noted that the concentration of pollutants generally increases during the HS. The PM4 and PM10 concentrations are excluded due to the effect of a Saharan dust transfer episode. The aforementioned dust episode occurs during the LS, affecting the PM concentrations over Western Greece. The higher ratio of PM2.5 to PM10 ( ) during the HS indicates that the shipping contributes to the increase in the air pollution of Igoumenitsa. The analysis emphasizes that during the studied periods (HS and LS), the shipping and harbor activities affect the air quality of Igoumenitsa. Finally, this case study demonstrates that a further investigation of air quality in the port for a long-temporal period can provide important results, which can help the competent authorities in adopting energy saving practices that reduce air pollution footprint in ports. Data Availability Statement: Publicly available datasets were analyzed in this study. These data can be found here: http://www.bsc.es/ess/bsc-dust-daily-forecast/ (accessed on 14 June 2021), https://worldview.earthdata.nasa.gov (accessed on 10 June 2021), and https://giovanni.gsfc.nasa.gov/giovanni/ (accessed on 3 June 2021).

Conclusions
This work examines the effect of shipping and port operation on the pollution levels of Igoumenitsa in Western Greece. The analysis is carried out through a comparison of the high (HS) and low (LS) port activity season during 2018 and the obtained findings indicate that meteorology affects the concentration of pollutants. In particular, wind speed tends to reduce the concentration of the majority of pollutants. For both seasons, the elevated concentration of pollutants occurs during the hours of high shipping traffic. It should be noted that the concentration of pollutants generally increases during the HS. The PM 4 and PM 10 concentrations are excluded due to the effect of a Saharan dust transfer episode. The aforementioned dust episode occurs during the LS, affecting the PM concentrations over Western Greece. The higher ratio of PM 2.5 to PM 10 (R PM ) during the HS indicates that the shipping contributes to the increase in the air pollution of Igoumenitsa. The analysis emphasizes that during the studied periods (HS and LS), the shipping and harbor activities affect the air quality of Igoumenitsa. Finally, this case study demonstrates that a further investigation of air quality in the port for a long-temporal period can provide important results, which can help the competent authorities in adopting energy saving practices that reduce air pollution footprint in ports.