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- Evgenieva, Tsvetina, et al.
(författare)
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Three-point observation in the troposphere over Sofia-Plana Mountain,Bulgaria
- 2011
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Ingår i: International Journal of Remote Sensing. - : Informa UK Limited. - 0143-1161 .- 1366-5901. ; 32:24, s. 9343-9363
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Tidskriftsartikel (refereegranskat)abstract
- Based on a novel combination of approaches and instruments, this article presents campaign-based results from atmospheric boundary layer (ABL) height and aerosol optical depth (AOD) measurements carried out at two different experimental sites in Sofia, as well as from three-point measurements of aerosol number concentrations. Several instruments (lidar (developed by the IE), ceilometer, aerosol particle counter, sun photometer and meteorological sensors) were used in this study. Based on joint interpretation of the instruments' data we assess the influence of the atmospheric aerosol in the planetary boundary layer and the significant influence of aerosol layers and high clouds on AOD values. Measurements of AOD in the city basin gave values in the range 0.22-0.41 for cloud-free skies, and up to around 0.8 under partly cloudy conditions. The information obtained during the two campaigns indicates that aerosol particle concentrations were lower in park areas than along heavy-traffic thoroughfares in the city, but higher than in the mountain area. In conclusion, our study demonstrates the potential of employing a broad array of instruments for the study of boundary layer and aerosol over large, valley-situated and heavily urbanized city areas.
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| 6. |
- Enckell, P H, et al.
(författare)
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The dispersal pattern of an anthropochorous species: Genetic variation in populations of Lumbricus terrestris L. (Lumbricidae) in the Faroe Islands
- 1986
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Ingår i: Hereditas. - : Springer Science and Business Media LLC. - 0018-0661 .- 1601-5223. ; 104:2, s. 253-261
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Tidskriftsartikel (refereegranskat)abstract
- Ten populations of the anthropochorous Lumbricus terrestris L. (Lumbricidae) from six islands in the Faroes were scored for enzyme variation by electrophoresis. The allele frequencies were analyzed by cluster analysis and information entropy relationships. There was a significant heterogeneity in allele frequencies among the samples. Four groups could be distinguished in the cluster analysis of which one was larger (at least five sites); two sites were defined as outliers. Information entropy showed that the allele frequency data were structured differently over the sites and that the most non-random site was also one of the outliers in the cluster space. The main group in the cluster analysis also forms a geographically central group in the islands. These results are discussed against the known colonization history of the Faroes. It is concluded that the genetic variation pattern does not indicate any single point of invasion of L. terrestris into the islands. Rather, it shows that former and present-day communications between the islands are responsible for similarities and dissimilarities in genetic variation in the L. terrestris populations.
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| 7. |
- Evgenieva, Tsvetina, et al.
(författare)
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Lidar, ceilometer and sun photometer investigation of the aerosol optical characteristics in the troposphere over Sofia, Bulgaria
- 2010
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Ingår i: Comptes Rendus de l'Academie Bulgare des Sciences / Proceedings of the Bulgarian Academy of Sciences. - 1310-1331 .- 2367-5535. ; 63:8, s. 1191-1200
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Tidskriftsartikel (refereegranskat)abstract
- The paper presents the results from planetary boundary layer (PBL) height and aerosol optical depth (AOD) measurements carried out in two different experimental sites in Sofia as well as from three-point measurements of aerosol number concentration.The main aim of the present investigation is to determine optical and microphysical characteristics of the atmospheric aerosol in three points of the valley and their variation during the PBL formation over urban area, park zone and mountain site. Four instruments (lidar, ceilometer, aerosol particle counter and sun photometer) were used in this study.The experimental AOD data obtained at lambda = 500nm gave values in the range from 0.22 to 0.41 in case of cloud-free skies and up to around 0.8 under partly cloudy conditions. Aerosol particle counter data on aerosol-particle concentration variations in the size range 0.3-1 mu m provided supportive information on the evolution of the valley-mountain aerosol in time and height during the mixing layer development. Joint interpretation of sun photometer, aerosol lidar and ceilometer CHM 15k data allow the influence of the main part of the atmospheric aerosol in the planetary boundary layer to be accounted as well as the significant influence of aerosol layers and high clouds on AOD values.
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| 9. |
- Ibrahim, Muhammad Asim, 1980-, et al.
(författare)
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Mitigating the emissions released from spontaneous fires at biomass storages : A footstep towards sustainability
- 2015
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Ingår i: 23rd European Biomass Conference and Exhibition, Vienna, Austria, 1-4 June 2015. - 9788889407516 ; , s. 1550-1557
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Konferensbidrag (refereegranskat)abstract
- Fires at the material storages sites of manucipal and industrial sectors are a major environmental risk and have increased significantly. Toxic emissions released from such open fires have severe environmental and health consequences. Considering that it is not possible to install any unit operation to control the emissions released from such open fires, the possibilities to employ natural vegetation to act as a sink for aerosol particles released from open fires was investigated. A series of tests was conducted in a controlled wind tunnel environment. Smoke was generated in a smoke-aerosol generator and measurements of smoke concentrations upwind and downwind of “green filter packs” (vegetation filters) were made. Measurements involved laser-based particle counters, two-stage Nuclepore filter systems, and Solid Phase Microextraction (SPME) techniques followed by Gas Chromatography-Mass Spectrometry (GC-MS). The main objective of the work was to illustrate ways to design experiments that can assist in the study of vegetation as “pollution screens”. Our observations and findings imply that several refinements to the experimental design will be needed, including with respect to methods for assessing the distribution of particle number and mass as a function of particle size.
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| 10. |
- Lövbrand, Eva, et al.
(författare)
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Earth System governmentality Reflections on science in the Anthropocene
- 2009
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Ingår i: GLOBAL ENVIRONMENTAL CHANGE-HUMAN AND POLICY DIMENSIONS. - : Elsevier BV. - 0959-3780 .- 1872-9495. ; 19:1, s. 7-13
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Tidskriftsartikel (refereegranskat)abstract
- This paper examines Earth System Science as a novel approach to global environmental change research. Drawing upon Michel Foucaults governmentality concept, the paper opens up the Earth System metaphor to political analysis and asks what it does to our understanding of nature and society as a governable domain. We trace the scientific practices that have produced the Earth System as a thinkable analytical category back to the International Geophysical Year in 1957. We also identify the Anthropocene as a central and yet ambiguous system of thought for Earth System Science that harbours different strategies for sustainability in terms of (1) the persons over whom government is to be exercised; (2) the distribution of tasks and actions between authorities; and (3) contrasting ideals or principles for how government should be directed.
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