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  • Open access
  • 68 Reads
Effect of aging on the complex refractive index of pure submicron clay particle

Modelling the optical and radiative properties of atmospheric particles are governed by one of the key input parameters i.e. refractive index of aerosols. Availability of the region-specific refractive index data of aerosol is major challenge for atmospheric community. The complex refractive index of aerosol is function of their physico-chemical properties. Uncertainty in the computation of the spectral refractive indices of the aerosol leads to erroneous assessment of their optical and radiative properties.

Refractive index of pure clay (Kaolinite and Illite) and polluted clay [Kaolinite, Illite, anthropogenic hematite, AH (0.10 to 1.48%), black carbon, BC (2 to 10%), ammonium sulphate, AS (13%) and ammonium nitrate, AN (8%)] submicron particle have been computed for the wavelength range 0.38 to 21.5 µm. Anthropogenic hematite enhanced the overall absorption in the UV and Visible range with maximum absorption upto 0.55 µm wavelength. Aging of the pure submicron clay particles with pollutants (AH, BC, AS, AN) significantly enhanced the imaginary part of the refractive index (k) in near infrared window (0.86 to 21.5 µm) of the solar radiation. Mixture of 1.48% AH and 10% BC shows maximum absorption in the UV, Visible and NIR region. Highest “k”value (1.2) was observed corresponding to 21.5 µm wavelength. The detailed insights of the study will be talked during the conference.

  • Open access
  • 179 Reads
The air quality during the confinement and coronavirus 2020-2021 period.

At the end of 2019, the first cases of coronavirus (COVID-19) were reported in Wuhan, China. A month later, that epidemic turned into a national crisis, with infected individuals diagnosed all over China. In early March 2020, the World Health Organization (WHO) declared that the Wuhan epidemic has turned into a global pandemic. Many European countries have started to know several cases affected by this coronavirus, which is known to be highly contagious. The WHO has launched several recommendations to curb the spread of this virus and to call for the establishment of general confinement in the affected countries. Tunisia quickly took this step on March 22 and announced immediate general confinement for two weeks, renewable according to the tests results. Factories have been closed to limit human damage. International flights have been halted and the majority of government and private services have been halted except minimum and emergency services. Following these successive events, the air quality has improved markedly during the confinement period. NASA scientists say the reduction in NO2 pollution first appeared near Wuhan Northern Italy and France experienced a reduction of nearly 50% of their NO2 emissions during this period of confinement (March-April) and been reduced by almost 30% in China. In Tunisia, nitrogen dioxide (NO2), sulfur dioxide (SO2) and carbon monoxide (CO) showed a remarkable decrease in the north and the center of Tunisia of more than 40% during this period mainly linked to the reduction in emissions from road traffic and industries. Also these pollutant gases concentrations have knew a nearly 50% reduction during the 3rd pandemic wave during the period of January-April 2021. Consequently, the air quality has improved significantly in Tunisia and around the world.

  • Open access
  • 86 Reads
Comparison analysis of the effect of high and low port-activity season on air quality in the port of Heraklion

Emissions from port operation and shipping have a significant impact on climate risk affecting the environment and human health in coastal regions (UNEP; IPCC). The port of Heraklion, located on the island of Crete over the eastern Mediterranean, plays a key role in the sustainability of Southeast Europe. Its impact on operation affects the socio-economic life and development because Heraklion is not just a tourist destination, but also a significant trade and transportation center over the eastern Mediterranean. This study investigates the impact of port operation on the air quality of Heraklion between two representative periods. The first, which is considered as the high port-activity season was conducted from 02.08.2018 to 08.08.2018, while the second one between 11.05.2018 and 16.05.2018. For the air quality measurements, a low-cost sensor is used while the recordings are initially compared and finally evaluated based on the available data of the monitoring station of the Ministry of Environment and Energy. To investigate the air quality differences between the two studied periods, the correlation analysis, the hourly evolution of pollutants, the mean differences between high and low period for gaseous pollutants and particulate matter are studied. Moreover, the effect of meteorology on air quality is investigated. The results indicate that the high season is characterized by significantly higher concentrations of pollutants compared to the other. In both seasons studied, the air pollution level increases during hours of high port-activity indicating the impact of the port-activity on air quality in Heraklion. The analysis shows that meteorology affects the air quality. In particular, strong wind speeds are associated with lower concentrations of gaseous pollutants other than ozone which is affected by atmospheric circulation. Finally, the analysis emphasizes the importance of further investigation of the impact of port operations on coastal air quality in the context of sustainable development.

  • Open access
  • 242 Reads
Measurements of SARS-CoV-2 RNA concentrations in indoor and outdoor air in Italy: implications for the role of airborne transmission

Since the beginning of COVID-19 pandemic there have been scientific questions regarding the role of airborne transmission of SARS-CoV-2 and its influence on COVID-19 spread. One of the key parameters to ascertain the risks of airborne transmission is the concentrations of SARS-CoV-2 genetic material (RNA) in air in different environments. This work investigates this aspect in both outdoor and indoor environments in different towns of Italy during the first and the second wave of pandemic. Outdoor samples were collected using both PM10 low-volume (2.3 m3/h) samplers for 48h in parallel in Venice (Veneto region, north-east of Italy) and Lecce (Puglia region, south-east of Italy) during the first wave of pandemic. In addition, two samples for each site were collected using MOUDI multistage impactors (1.8 m3/h for six days sampling) able to separate 12 size ranges of particles. During the second wave of pandemic in Italy (November-December 2020), air samples were collected in different community indoor environments: one train station and two food markets in metropolitan city of Venice (Veneto Region); one canteen in Bologna (Emilia-Romagna region, central Italy); one shopping centre, one hair salon, and one pharmacy in Lecce (Puglia region). All collected samples were analysed to individuate the presence of SARS-CoV-2 RNA traces using two independent approaches: real-time RT-PCR and ddPCR (Chirizzi et al., 2021). Recovery tests done using Mengo virus strain MC0 indicate a recovery of about 50%. Modelling of expected average concentrations in the different environments, were also done using influx of customers data and local epidemiological information to compare with measurements. Results show a negligible risk for airborne transmission in residential outdoor zones, excluding crowed areas. In the community indoor environments investigated, indoor ventilation seems to play an important role in reducing concentrations of virus-laden particles as well as the use of facemasks.

  • Open access
  • 62 Reads
Moisture sources for the explosive cyclogenesis of extratropical cyclone Miguel (2019) through a Lagrangian approach

In this study, the moisture sources for the explosive cyclogenesis Miguel (4-9 June 2019) that occurred in the North Atlantic were investigated. To determine the moisture sources, the Lagrangian FLEXPART particle dispersion model was used. The moisture uptake pattern revealed the western North Atlantic Ocean extending to north-western North America, the south-eastern coast of Greenland and the central North Atlantic Ocean around 45ºN and 50º-20ºW as the main moisture sources for Miguel explosive cyclogenesis. Furthermore, the moisture uptake from these regions was higher than the climatology. During the intensification of Miguel, the moisture contribution from oceanic sources was higher than terrestrial sources. Although the total amount of atmospheric moisture achieved during the explosive intensification was similar to that absorbed the 24 hours prior, they changed in intensity geographically, being more intense the local support over the central and northern North Atlantic basin.

  • Open access
  • 66 Reads
Performance evaluation of Numerical Tools for Hurricane Forecast (NTHF) system during 2020 North Atlantic tropical cyclones season

This study evaluates the performance of the Numerical Tools for Hurricane Forecast (NTHF) system during the 2020 North Atlantic (NATL) tropical cyclones (TCs) season. The system is configured to provided 5-day forecasts with basic input from the National Hurricane Center (NHC) and the Global Forecast System. For the NTHF validation, the NHC operational best track was used. The average track errors for 2020 NATL TCs ranged from 48 km at 12 h to 368 km at 120 h. The NTHF track forecast errors displayed an improvement higher than 60% over the guidance Climatology and Persistence (CLIPER) model from 36 h to 96 h, although NTHF was better than CLIPER in all forecast period. The forecasts errors for the maximum wind speed (minimum central pressure ) ranged between 20 km/h and 25 km/h (4 hPa to 8 hPa), but the NTHF model intensity forecasts showed only marginal improvement less than 20% after 78 h over the baseline Decay Statistical Hurricane Intensity Prediction Scheme (D-SHIPS) model. Nevertheless, NTHF's ability to forecast the trajectory and intensity of the 2020 NATL TCs was higher than the NTHF average ability in the 2016-2019 period.

  • Open access
  • 62 Reads
Impact of climate change in forest fire generation in Las Tunas, Cuba

In the last decades, the affected area and the severity of forest fires has increased in many regions of the world, and, without farsighted adjustments, it is likely that the climate change increases the intensity and frequency of them. The purpose of this paper is to determine the possible impact of the climate change in generating forest fires in Las Tunas, a vulnerable region to process of aridity, drought, forest fires and furthermore, one of the most deforested regions in Cuba. Considering meteorological variables characteristics, aridity and forest fires behavior, it was developed a long term index which allows to determine zones with favorable conditions to beginning and development of forest fires by month. That created index was evaluated considering the possible changes in meteorological variables in RCP2.6 and RCP8.5 scenarios, in 2020-2049, 2050-2079 and 2080-2099 periods. In general, Las Tunas is moving to warmer conditions, with a reduction in rainfall, especially in the north coast, and a decrease of relative humidity, which will cause more affected zones by aridity and drought, and bigger areas with forest fires danger.

  • Open access
  • 105 Reads
Assessment of thermal environment and thermal comfort during 2021 National Intercollegiate Athletic Games period

Due by the impact regarding global warming and extreme weather events, outdoor thermal condition become tougher and harder to mitigate especially for pedestrian movement and exercises. In order to better understand the thermal environment and thermal comfort especially for outdoor sports, 2021 National Intercollegiate Athletic Games held at Tainan, southern Taiwan, in May has been selected as the research target. Both on site real-time environmental monitoring data (Temperature, Relative Humidity, Wind Speed, PM2.5, Sky View Factor), and Taiwan Climate Change Projection Information and Adaptation Knowledge Platform (TCCIP) Taiwan ReAnalysis Downscaling data (TReAD) were applied in estimating mPET (modified Physiologically Equivalent Temperature) and WBGT (Wet-bulb Globe Temperature) for members participating the Games. 200-300 questionnaires were obtained among the staffs, volunteers, athletes and audiences participating the Games for detailed analysis of the connection between the environmental condition and physical sensation.

This study interests in assessing the thermal performance among those outdoor sport events held in southern Taiwan. Since there will be many college students and faculties gathering and joining the Games as staffs, volunteers, athletes and audiences during the event period. And they would be exposed under the direct solar radiation from time to time. This study would focus on the thermal and health impacts/ risk toward staffs, volunteers, athletes and audiences at the venue during the Games.

  • Open access
  • 65 Reads
Spatio-temporal assessment of meteorological drought in Puerto Rico between 1950 and 2019

The phenomenon of drought is one of the most dangerous for small islands because of its impacts on freshwater availability. Thus, in this study was investigated the spatio-temporal evolution of meteorological drought that affected the main island of Puerto Rico in the period 1950 – 2019. To do it, the Standardised Precipitation-Evapotranspiration Index (SPEI) using monthly values of minimum and maximum temperature, and of precipitation derived from Daymet Version 4 daily data at a 1 km x 1 km spatial resolution was used. At 1-month temporal scale the SPEI shows great temporal variability, the occurrence of 85 meteorological drought episodes, but a clear tendency towards wetting, principally in the last years of the study period. The spatial analysis also revealed that major affectation by moderate drought conditions has occurred across the half west and south of the island, by severe drought also in the half west of the island as well as along the eastern coast, and finally, the extreme drought conditions, which have been less frequent has principally affected the northeast of the country. However, a trend analysis of the area affected by moderate, severe, and extreme drought conditions revealed a tendency to decrease, which is reflected by the prevalence of positive spatial trends of the SPEI1 across the country.

  • Open access
  • 66 Reads
Microbursts nowcasting for the Havana’s International Airport José Martí using a weather radar.

The low level wind shear has been the cause of many aviation incidents and accidents. This work is about the development of a nowcasting method for low level wind shear produced by microbursts in the Havana’s International Airport “José Martí”. Using Vesta Process software for the analysis of Casablanca’s weather radar observations, it was identified patterns of radio-echoes associated with microbursts which produced wind gusts higher than 30 knots. For that, it was analyzed the meteorological radar images considering echoes intensity in dBZ, the reached height and the morphology of them, as well as the proximity to the airport and the movement of the cumulonimbus clouds that represent damage for it and the air traffic operations. It was established a procedure to emit microbursts alerts and alarms for the airport.