scholarly journals A SEA BREEZE NUMERICAL SIMULATION AND CIRCULATION ANALYSIS IN ORAN, ALGERIA, URBAN ATMOSPHERE

2016 ◽  
Vol 9 (2) ◽  
pp. 139-145
Author(s):  
Abdelkrim Benlefki ◽  
Benouada Douaiba ◽  
Azzi Abbes
Keyword(s):  
Numerical Simulation ◽  
Sea Breeze ◽  
Urban Atmosphere ◽  
Atmospheric Flow ◽  
The North ◽  
Grid Simulation ◽  
Surface Data ◽  
Spatio Temporal ◽  
North Algeria

In this paper the sea breeze dynamics in Oran agglomeration atmosphere, in the north Algeria, is investigated and analyzed by a numerical simulation of Oran agglomeration atmosphere, using SUBMESO model during diurnal cycle of June 24, 2010, in order to predict the spatio-temporal starting of sea breeze, its intensity and relative direction through atmospheric flow variations analysis, and to evaluate the role of thermal circulations on sea breeze direction, intensity and ventilation and its effect on pollutant transport. The study of this area has not been investigated or analyzed in any framework, the numerical simulation was preceded by a topographic and surface data processing in order to generate the grid simulation, with a specific characteristics used by the SUBEMESO and SM2-U (Soil Model for Sub-Meso scales Urbanized) models. This simulation allowed us to know all sea breeze characteristics during the study period.

scholarly journals A SEA BREEZE NUMERICAL SIMULATION AND CIRCULATION ANALYSIS IN ORAN, ALGERIA, URBAN ATMOSPHERE

2016 ◽  
Vol 9 (2) ◽  
pp. 139-145
Author(s):  
Abdelkrim Benlefki ◽  
Benouada Douaiba ◽  
Azzi Abbes
Keyword(s):  
Numerical Simulation ◽  
Sea Breeze ◽  
Urban Atmosphere ◽  
Atmospheric Flow ◽  
The North ◽  
Grid Simulation ◽  
Surface Data ◽  
Spatio Temporal ◽  
North Algeria

In this paper the sea breeze dynamics in Oran agglomeration atmosphere, in the north Algeria, is investigated and analyzed by a numerical simulation of Oran agglomeration atmosphere, using SUBMESO model during diurnal cycle of June 24, 2010, in order to predict the spatio-temporal starting of sea breeze, its intensity and relative direction through atmospheric flow variations analysis, and to evaluate the role of thermal circulations on sea breeze direction, intensity and ventilation and its effect on pollutant transport. The study of this area has not been investigated or analyzed in any framework, the numerical simulation was preceded by a topographic and surface data processing in order to generate the grid simulation, with a specific characteristics used by the SUBEMESO and SM2-U (Soil Model for Sub-Meso scales Urbanized) models. This simulation allowed us to know all sea breeze characteristics during the study period.

scholarly journals Towards Reliable Velocities of Permanent GNSS Stations

2016 ◽  
Vol 100 (1) ◽  
pp. 17-26
Author(s):  
Janusz Bogusz ◽  
Anna Klos ◽  
Marta Gruszczynska ◽  
Maciej Gruszczynski
Keyword(s):  
Time Series ◽  
Singular Spectrum Analysis ◽  
Principal Component ◽  
North East ◽  
Temporal Correlations ◽  
The North ◽  
Spatio Temporal ◽  
Permanent Station

Abstract In the modern geodesy the role of the permanent station is growing constantly. The proper treatment of the time series from such station lead to the determination of the reliable velocities. In this paper we focused on some pre-analysis as well as analysis issues, which have to be performed upon the time series of the North, East and Up components and showed the best, in our opinion, methods of determination of periodicities (by means of Singular Spectrum Analysis) and spatio-temporal correlations (Principal Component Analysis), that still exist in the time series despite modelling. Finally, the velocities of the selected European permanent stations with the associated errors determined following power-law assumption in the stochastic part is presented.

scholarly journals <i>Brief communication</i> "Important role of the mid-tropospheric atmospheric circulation in the recent surface melt increase over the Greenland ice sheet"

2013 ◽  
Vol 7 (1) ◽  
pp. 241-248 ◽  
Author(s):  
X. Fettweis ◽  
E. Hanna ◽  
C. Lang ◽  
A. Belleflamme ◽  
M. Erpicum ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Circulation Type ◽  
Atmospheric Flow ◽  
The North ◽  
Surface Melt ◽  
The North Atlantic Oscillation ◽  
June July ◽  
Atmospheric Heat

Abstract. Since 2007, there has been a series of surface melt records over the Greenland ice sheet (GrIS), continuing the trend towards increased melt observed since the end of the 1990's. The last two decades are characterized by an increase of negative phases of the North Atlantic Oscillation (NAO) favouring warmer and drier summers than normal over GrIS. In this context, we use a circulation type classification based on daily 500 hPa geopotential height to evaluate the role of atmospheric dynamics in this surface melt acceleration for the last two decades. Due to the lack of direct observations, the interannual melt variability is gauged here by the summer (June–July–August) mean temperature from reanalyses at 700 hPa over Greenland; analogous atmospheric circulations in the past show that ~70% of the 1993–2012 warming at 700 hPa over Greenland has been driven by changes in the atmospheric flow frequencies. Indeed, the occurrence of anticyclones centred over the GrIS at the surface and at 500 hPa has doubled since the end of 1990's, which induces more frequent southerly warm air advection along the western Greenland coast and over the neighbouring Canadian Arctic Archipelago (CAA). These changes in the NAO modes explain also why no significant warming has been observed these last summers over Svalbard, where northerly atmospheric flows are twice as frequent as before. Therefore, the recent warmer summers over GrIS and CAA cannot be considered as a long-term climate warming but are more a consequence of NAO variability affecting atmospheric heat transport. Although no global model from the CMIP5 database projects subsequent significant changes in NAO through this century, we cannot exclude the possibility that the observed NAO changes are due to global warming.

Numerical simulation of the controlling role of geofluids in the thinning process of the North China Craton

2009 ◽  
Vol 101 (1) ◽  
pp. 122
Author(s):  
Lu Zhang ◽  
Ge Lin ◽  
Chongbin Zhao ◽  
Deshun Zhang ◽  
Shilin Liu
Keyword(s):  
Numerical Simulation ◽  
North China Craton ◽  
North China ◽  
The North ◽  
Thinning Process

scholarly journals Galápagos macroalgae: A review of the state of ecological knowledge

2016 ◽  
Vol 65 (1) ◽  
pp. 375 ◽  
Author(s):  
Paul Tompkins ◽  
Matthias Wolff
Keyword(s):  
Marine Ecosystem ◽  
Critical Role ◽  
Future Research ◽  
Ecological Knowledge ◽  
Sources Of Information ◽  
Enso Events ◽  
The North ◽  
Marine Food ◽  
Spatio Temporal

Previous work has highlighted the critical role of macroalgal productivity and dynamics in supporting and structuring marine food webs. Spatio-temporal variability in macroalgae can alter coastal ecosystems, a relationship particularly visible along upwelling-influenced coastlines. As a result of its equatorial location and nutrient rich, upwelling-influenced waters, the Galápagos Archipelago in the East Pacific, hosts a productive and biodiverse marine ecosystem. Reports and collections of macroalgae date back to the Beagle voyage, and since then, more than three hundred species have been reported. However, their ecology and functional role in the ecosystem is not well understood. According to various disparate and in part anecdotal sources of information, abundant and diverse communities exist in the Western regions of the archipelago, the North is essentially barren, and in the central/South abundance and distribution is variable and less well defined. Both oceanographic conditions and herbivore influence have been theorized to cause this pattern. Extensive changes in macroalgal productivity and community composition have occurred during strong ENSO events, and subsequent declines in marine iguana (an endemic and iconic grazer) populations have been linked to these changes. Iguanas are only one species of a diverse and abundant group of marine grazers in the system, highlighting the potentially important role of macroalgal productivity in the marine food web. This review represents a first compilation and discussion of the available literature and presents topics for future research.

scholarly journals Brief communication "Important role of the mid-tropospheric atmospheric circulation in the recent surface melt increase over the Greenland ice sheet"

2012 ◽  
Vol 6 (5) ◽  
pp. 4101-4122 ◽  
Author(s):  
X. Fettweis ◽  
E. Hanna ◽  
C. Lang ◽  
A. Belleflamme ◽  
M. Erpicum ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Circulation Type ◽  
Atmospheric Flow ◽  
The North ◽  
Surface Melt ◽  
The North Atlantic Oscillation ◽  
June July ◽  
Atmospheric Heat

Abstract. Since 2007, there has been a succession of surface melt records over the Greenland Ice Sheet (GrIS) in continuity of the trend observed since the end of the 1990s towards increasing melt. But, these last two decades are characterized by an increase of negative phases of the North-Atlantic Oscillation (NAO) favouring warmer and drier summers than normal over GrIS. In this context, we use a circulation type classification based on the daily 500 hPa geopotential height to evaluate the role of the atmospheric dynamics in this surface melt acceleration since 20 yr. Due to the lack of direct observations, the interannual melt variability is gauged here by the summer (June-July-August) mean temperature at 700 hPa over Greenland; analogous atmospheric circulations in the past show that ~70% of the 1992–2011 warming at 700 hPa over Greenland has been driven by changes in the atmospheric flow frequencies. Indeed, the occurrence of anticyclones in surface and at 500 hPa centred over the GrIS has doubled since the end of 1990s which induces southerly warm air advection along the Western Greenland coast and over the neighbouring Canadian islands. These changes in the NAO modes explain also why no significant warming has been observed these last five summers over Svalbard, where northerly atmospheric flows are more frequent than before. Therefore, the recent warmer summers over Greenland, Ellesmere and Baffin Islands can not be considered as a long term climate warming but are more rather a consequence of the NAO variability impacting the atmospheric heat transport. While no global model from the CMIP5 database projects consequent changes in NAO through this century, we can not exclude that these changes in NAO are due to global warming.

The Inherited Past of the Broch: On Antiquarian Discourse and Contemporary Archaeology

2002 ◽  
Vol 24 (1) ◽  
pp. 1-20 ◽  
Author(s):  
ANDREW BAINES
Keyword(s):  
Material Culture ◽  
19Th Century ◽  
Academic Language ◽  
Contemporary Archaeology ◽  
The North

In reading archaeological texts, we expect to be engaged in a characteristically archaeological discourse, with a specific and recognisable structure and vocabulary. In evaluating the published work of 19th Century antiquarians, we will inevitably look for points of contact between their academic language and our own; success or failure in the identification of such points of contact may prompt us to recognise a nascent archaeology in some writings, while dismissing others as naïve or absurd. With this point in mind, this paper discusses the written and material legacies of three 19th Century antiquarians in the north of Scotland who worked on a particular monument type, the broch. The paper explores the degree to which each has been admitted as an influence on the development of the broch as a type. It then proceeds to compare this established typology with the author's experiences, in the field, of the sites it describes. In doing so, the paper addresses wider issues concerning the role of earlier forms of archaeological discourse in the development of present day archaeological classifications of, and of the problems of reconciling such classifications with our experiences of material culture.

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