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| 2. |
- Grundström, Maria, 1979, et al.
(författare)
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Influence of atmospheric circulation patterns on urban air quality during the winter
- 2015
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Ingår i: Atmospheric Pollution Research. - 1309-1042. ; 6:2, s. 278-285
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Tidskriftsartikel (refereegranskat)abstract
- Relationships between urban nitrogen dioxide (NO2) and atmospheric circulation at two spatial scales were studied for Southern Sweden. Lamb Weather Types (LWT) describe the circulation (scale: thousands of kilometers) including non–directional (cyclonic and anticyclonic) and directional types depending on the wind direction. LWTs with low wind speeds (anticyclonic, NW and N) were associated with strongly elevated [NO2], between 46–52% of the daily averages of NO2 exceeded the 60 μg m–3 air quality standard (AQS) when occurring during these LWTs. The lowest fractions of exceedances of NO2 AQS were generally observed for LWTs E, S, SW and W. A larger scale circulation (several thousands of kilometers) was represented by the North Atlantic Oscillation (NAO) affecting meteorology over middle and high latitudes in the Northern Hemisphere. While a negative NAO index (NAOI) favors stagnant high pressure weather over Northern Europe, a positive NAOI is often associated with windy conditions. High [NO2] was found to be frequent under negative NAOI. Additionally, larger fractions of exceedances of NO2 AQS were observed for the majority of LWTs occurring at negative NAOI. It’s concluded that both LWTs and NAOI had partly independent effects on the urban air quality in a North European city. These circulation indices can be useful tools for air pollution risk assessment and forecasting.
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| 3. |
- Kang, Sang Hoon, et al.
(författare)
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Directional spillover effects between ASEAN and world stock markets
- 2019
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Ingår i: Journal of Multinational Financial Management. - : ELSEVIER. - 1042-444X .- 1873-1309. ; 52-53
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Tidskriftsartikel (refereegranskat)abstract
- We investigate dynamic spillovers between ASEAN-5 and world stock markets using a dynamic equicorrelation (DECO) model and the spillover index of Diebold and Yilmaz (2012)), which identifies net directional spillovers for each one of the markets. The DECO model uses more information to calculate dynamic correlations between each pair of returns than standard dynamic conditional correlation models, decreasing the estimation noise of the correlations. Directional spillovers from world stock markets to ASEAN-5 stock markets are higher than in the opposite direction. Besides, our results indicate heterogeneity among the ASEAN-5 stock markets in the degree of spillover to world markets over time. We verify an increase in both return and volatility spillovers during financial crises, confirming the intensity of information transmission during periods of turmoil. These findings help understand the economic channels through which the ASEAN-5 equity markets are connected, and have important implications for emerging and frontier markets. (C) 2019 Elsevier B.V. All rights reserved.
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| 4. |
- Tiwari, Suresh, et al.
(författare)
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Assessment of PM2.5 and PM10 over Guwahati in Brahmaputra River Valley : Temporal evolution, source apportionment and meteorological dependence
- 2017
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Ingår i: Atmospheric Pollution Research. - : Elsevier BV. - 1309-1042. ; 8:1, s. 13-28
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Tidskriftsartikel (refereegranskat)abstract
- Temporal evolution, source apportionment and transport pathways of particulate matter (PM2.5 and PM10) are analysed over Guwahati, located in the Brahmaputra River Valley (BRV), as a function of meteorological dynamics. During the study period (July 2013-June 2014), the mean PM2.5 and PM10 mass concentrations were found to be 52 +/- 37 and 91 +/- 60 mu g m (-3), respectively, both exhibiting higher concentrations during DecembereMarch and very low during summer. The annual mean ratio of PM2.5/ PM10 was 0.57 +/- 0.11, varying from 0.24 to 0.86, suggesting dominance of anthropogenic vs natural emissions during winter and spring, respectively. Diurnal variation reveals higher PM concentrations during morning (similar to 9: 00 local time (LT)) and evening (similar to 23: 00 LT) and lowest around similar to 14: 00 to 17: 00 LT due to influence of dilution processes and higher mixing-layer height over the region. Bivariate plots and Conditional Bivariate Probability Function (CBPF) analysis showed that the highest PM2.5 and PM10 concentrations are mostly associated with weak northwestern winds (< 1.5 ms (- 1)) in all seasons except spring, when the highest PM10 are for southwestern winds above 4-6 ms(- 1), indicating dust transport from SW Asia. Analysis reveals that the local emissions, transported aerosols, along with seasonallychanged air masses, meteorology and boundary-layer dynamics control the concentrations, evolution and fractions of PM over BRV. The turbid air masses transported over Guwahati mostly from western and southwestern directions contribute to higher PM concentrations, either carrying anthropogenic pollution from Indo-Gangetic Plains or locally and LRT dust from BRV and western India, respectively.
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| 5. |
- Uddin, Gazi Salah, et al.
(författare)
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The impact of financial and economic factors on Islamic mutual fund performance: Evidence from multiple fund categories
- 2019
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Ingår i: Journal of Multinational Financial Management. - : ELSEVIER. - 1042-444X .- 1873-1309. ; 52-53
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Tidskriftsartikel (refereegranskat)abstract
- We examine the influence of financial, economic, and seasonal factors on the performance of international equity, fixed income, cash, and balanced Islamic mutual funds. We analyze monthly mutual fund return observations on 106 funds over 1997-2019 to investigate exposure to global developed Fama and French {1993, 2015) factors for equity and balanced funds, the three factors of Huij and Derwall {2008] for cash and bond funds, and monthly seasonal effects. Seasonal effects are insignificant in balanced, equity, and cash funds. The Fama and French factors significantly affect the performance of equity and balanced funds, whereas the three factors of Huij and Derwall are important in explaining the performance of cash and fixed income funds for almost over the whole year. Our findings suggest that investors should not be concerned about a potential seasonal effect due to the Ramadan period. (C) 2019 Elsevier B.V. All rights reserved.
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| 6. |
- Zalakeviciute, R., et al.
(författare)
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Chemical characterization of urban PM10 in the Tropical Andes
- 2019
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Ingår i: Atmospheric Pollution Research. - : Elsevier BV. - 1309-1042. ; 11:2, s. 343-356
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Tidskriftsartikel (refereegranskat)abstract
- Complex inhalable particles have become one of the main causes to trigger health problems worldwide. While the level of concern depends on the chemical composition of these particles, some regions are poorly studied, particularly, the Andes. In this work, the chemical characterization of atmospheric PM10 filter samples, collected between January and October of 2017, was carried out for the first time in the world's highest capital, Quito, Ecuador. This study investigates PM10 relation with meteorological variables and criteria pollutants. Average PM10 concentrations ranged from 24.9 μg m−3 to 26.2 μg m−3, with some alarming peaks during the episodes of fires and New Year's celebration. The major elements at study sites were Ca, Na, S, Mg, P, K, Fe, Si and Al, while the major water-soluble ion was SO42−. Meteorology plays an important role at this complex terrain city. Factor analysis showed natural dust and soil resuspension as the main source of particulate matter. Moreover, two less urbanized sites showed evidence of industrial activities or airport emissions, while the central city site showed a very strong signal of traffic-related pollution. These results are compared with representative cities around the world. As is the case in developing countries, low-quality diesel fuel is recognized for emitting large amounts of heavy metals, resulting in higher levels of those tracers in traffic flow areas. This work demonstrates the problems facing a midsize city, such as the lack of stricter regulations and, thus compromised air quality. This may imply serious respiratory and cardiovascular health effects.
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