scholarly journals Cloud Initialization in the Rapid Update Cycle of HIRLAM

2014 ◽  
Vol 29 (5) ◽  
pp. 1120-1133 ◽  
Author(s):  
Siebren de Haan ◽  
Siebe H. van der Veen
Keyword(s):  
Cloud Cover ◽  
Negative Impact ◽  
Heavy Precipitation ◽  
Temperature Fields ◽  
Cloud Base ◽  
Limited Area ◽  
Forecast Performance ◽  
First Case ◽  
Synoptic Observations

Abstract The Nowcasting Satellite Application Facility (NWC SAF) cloud mask from the Meteosat Second Generation (MSG) satellite is introduced in the initialization step of an hourly Rapid Update Cycle (RUC) of the High Resolution Limited Area Model (HIRLAM). MSG cloud-top temperatures and synoptic cloud-base height information are combined at analysis time. This cloud initialization scheme is applied to an experimental run, which is a copy of the operational Royal Netherlands Meteorological Institute [Koninklijk Nederlands Meteorologisch Instituut (KNMI)] RUC model. The experimental run was employed during the period June–December 2011. The RUC model has a forecast length of 6 h. Cloud cover forecasts are verified against MSG cloud cover information and synoptic observations. Forecasts of precipitation, surface pressure, 2-m temperature, and upper-air temperature are verified against synoptic observations and aircraft temperature observations. It is shown that including MSG cloud information in the RUC considerably improves the forecasts of most of these model fields, when compared to the operational control RUC. Both the bias and standard deviation of the errors of the cloud cover forecast are reduced substantially. Forecasts of light precipitation show a slight negative impact, but forecasts of heavy precipitation become better. The bias in 3D temperature fields disappears nearly completely. The error bias of 2-m temperatures has become larger. Two case studies are presented. The first case study had very good forecast performance with respect to low clouds when compared to the reference run. The second case study shows an ambiguous impact; there are still some deficiencies in the cloud initialization and cloud forecast when focusing on a single location.

scholarly journals A case study carried out with two different NWP systems

2006 ◽  
Vol 6 (5) ◽  
pp. 755-760
Author(s):  
P. Kållberg ◽  
A. Montani
Keyword(s):  
Weather Prediction ◽  
Heavy Precipitation ◽  
Northern Italy ◽  
Limited Area ◽  
Model Intercomparison ◽  
Atmospheric Models ◽  
Screen Level ◽  
Prediction Systems ◽  
Surface Fields

Abstract. A model intercomparison between two atmospheric models, the non–hydrostatic Lokal Modell (LM) and the hydrostatic HIgh Resolution Limited Area Model (HIRLAM) is carried out for a one-week period, including a case of cyclogeneis leading to heavy precipitation over Northern Italy. The two models, very different in terms of data-assimilation and numerics, provide different results in terms of forecasts of surface fields. Opposite diurnal biases for the two models are found in terms of screen level temperatures. HIRLAM wind speed forecasts are too strong, while LM precipitation forecasts have larger extremes. The intercomparison exercise identifies some systematic differences in the weather products generated by the two systems and sheds some light on the biases of the two numerical weather prediction systems.

scholarly journals Towards kilometer-scale ocean–atmosphere–wave coupled forecast: a case study on a Mediterranean heavy precipitation event

2021 ◽  
Vol 21 (15) ◽  
pp. 11857-11887
Author(s):  
César Sauvage ◽  
Cindy Lebeaupin Brossier ◽  
Marie-Noëlle Bouin
Keyword(s):  
Weather Prediction ◽  
Heavy Precipitation ◽  
Western Mediterranean ◽  
Precipitation Event ◽  
Coupled Modeling ◽  
Low Level ◽  
First Case ◽  
Short Period ◽  
Ocean Atmosphere

Abstract. The western Mediterranean Sea area is frequently affected in autumn by heavy precipitation events (HPEs). These severe meteorological episodes, characterized by strong offshore low-level winds and heavy rain in a short period of time, can lead to severe flooding and wave-submersion events. This study aims to progress towards an integrated short-range forecast system via coupled modeling for a better representation of the processes at the air–sea interface. In order to identify and quantify the coupling impacts, coupled ocean–atmosphere–wave simulations were performed for a HPE that occurred between 12 and 14 October 2016 in the south of France. The experiment using the coupled AROME-NEMO-WaveWatchIII system was notably compared to atmosphere-only, coupled atmosphere–wave and ocean–atmosphere simulations. The results showed that the HPE fine-scale forecast is sensitive to both couplings: the interactive coupling with the ocean leads to significant changes in the heat and moisture supply of the HPE that intensify the convective systems, while coupling with a wave model mainly leads to changes in the low-level dynamics, affecting the location of the convergence that triggers convection over the sea. Result analysis of this first case study with the AROME-NEMO-WaveWatchIII system does not clearly show major changes in the forecasts with coupling and highlights some attention points to follow (ocean initialization notably). Nonetheless, it illustrates the higher realism and potential benefits of kilometer-scale coupled numerical weather prediction systems, in particular in the case of severe weather events over the sea and/or in coastal areas, and shows their affordability to confidently progress towards operational coupled forecasts.

scholarly journals Radar adjusted data versus modelled precipitation: a case study over Cyprus

2006 ◽  
Vol 7 ◽  
pp. 85-90
Author(s):  
M. Casaioli ◽  
S. Mariani ◽  
C. Accadia ◽  
M. Gabella ◽  
S. Michaelides ◽  
...  
Keyword(s):  
Tropical Rainfall Measuring Mission ◽  
Heavy Precipitation ◽  
Radar Data ◽  
Skill Score ◽  
Rain Gauge ◽  
Limited Area ◽  
Rain Area ◽  
Open Questions ◽  
Skill Scores

Abstract. In the framework of the European VOLTAIRE project (Fifth Framework Programme), simulations of relatively heavy precipitation events, which occurred over the island of Cyprus, by means of numerical atmospheric models were performed. One of the aims of the project was indeed the comparison of modelled rainfall fields with multi-sensor observations. Thus, for the 5 March 2003 event, the 24-h accumulated precipitation BOlogna Limited Area Model (BOLAM) forecast was compared with the available observations reconstructed from ground-based radar data and estimated by rain gauge data. Since radar data may be affected by errors depending on the distance from the radar, these data could be range-adjusted by using other sensors. In this case, the Precipitation Radar aboard the Tropical Rainfall Measuring Mission (TRMM) satellite was used to adjust the ground-based radar data with a two-parameter scheme. Thus, in this work, two observational fields were employed: the rain gauge gridded analysis and the observational analysis obtained by merging the range-adjusted radar and rain gauge fields. In order to verify the modelled precipitation, both non-parametric skill scores and the contiguous rain area (CRA) analysis were applied. Skill score results show some differences when using the two observational fields. CRA results are instead quite in agreement, showing that in general a 0.27° eastward shift optimizes the forecast with respect to the two observational analyses. This result is also supported by a subjective inspection of the shifted forecast field, whose gross features agree with the analysis pattern more than the non-shifted forecast one. However, some open questions, especially regarding the effect of other range adjustment techniques, remain open and need to be addressed in future works.

scholarly journals Towards kilometer-scale ocean-atmosphere-wave coupled forecast: a case study on a Mediterranean heavy precipitation event

2021 ◽  
Author(s):  
César Sauvage ◽  
Cindy Lebeaupin Brossier ◽  
Marie-Noëlle Bouin
Keyword(s):  
Weather Prediction ◽  
Heavy Precipitation ◽  
Western Mediterranean ◽  
Precipitation Event ◽  
Coupled Modelling ◽  
Low Level ◽  
First Case ◽  
Short Period ◽  
Ocean Atmosphere

Abstract. The Western Mediterranean Sea area is frequently affected in autumn by heavy precipitation events (HPEs). These severe meteorological episodes, characterized by strong offshore low-level winds and heavy rain in a short period of time, can lead to severe flooding and wave-submersion events. This study aims to progress towards integrated short-range forecast system via coupled modelling for a better representation of the processes at the air–sea interface. In order to identify and quantify the coupling impacts, coupled ocean–atmosphere–wave simulations were performed for a HPE that occurred between October 12 and 14, 2016 in the South of France, using the coupled AROME-NEMO-WaveWatchIII system and notably compared to atmosphere only, coupled atmosphere–wave and ocean–atmosphere simulations. The results showed that the HPE fine-scale forecast is sensitive to both couplings: The interactive coupling with the ocean leads to significant changes in the heat and moisture supply of the HPE that intensify the convective systems, while coupling with a wave model mainly leads to changes in the low-level dynamics, affecting the location of the convergence that triggers convection over sea. Even if this first case study with the AROME-NEMO-WaveWatchIII system does not clearly show major changes in the forecasts with coupling and highlights some attention points to follow (ocean initialisation notably), it illustrates the higher realism and potential benefits of kilometer-scale coupled numerical weather prediction systems, in particular in case of severe weather events over sea and/or in coastal areas, and shows their affordability to confidently progress towards operational coupled forecasts.

Modernisation of Higher Education – Willful Action or Wishful Thinking? The Case of Bulgaria

2020 ◽  
Vol 8 (3) ◽  
pp. 3-17
Author(s):  
Elena Blagoeva
Keyword(s):  
Higher Education ◽  
Economic Crisis ◽  
Negative Impact ◽  
National Level ◽  
Sustainable Growth ◽  
Research Approach ◽  
Case Study Methodology ◽  
The Impact ◽  
The Eu

The impact of the last global economic crisis (2008) on the European economy put a strain on higher education (HE), yet it also pushed the sector towards intensive reforms and improvements. This paper focuses on the “Strategy for the Development of Higher Education in the Republic of Bulgaria 2014-2020”. With a case study methodology, we explore the strategic endeavours of the Bulgarian government to comply with the European directions and to secure sustainable growth for the HE sector. Our research question is ‘How capable is the Bulgarian HE Strategy to overcome the economic and systemic restraints of Bulgarian higher education?’. Because the development of strategies for HE within the EU is highly contextual, a single qualitative case study was chosen as the research approach. HE institutions are not ivory towers, but subjects to a variety of external and internal forces. Within the EU, this is obviated by the fact that Universities obtain their funds from institutions such as governments, students and their families, donors, as well as EU-level programmes. Therefore, to explore how these pressures interact to affect strategic action on national level, the case method is well suited as it enabled us to study the phenomena thoroughly and deeply. The paper suggests the actions proposed within the Strategy have the potential to overcome the delay, the regional isolation and the negative impact of the economic crisis on the country. Nevertheless, the key elements on which the success or failure of this Strategy hinges are the control mechanisms and the approach to implementation. Shortcomings in these two aspects of strategic actions in HE seem to mark the difference between gaining long-term benefits and merely saving face in front of international institutions.

Is There Racial Discrimination in Police Stop-and-Searches of Black Youth? A Toronto Case Study

2015 ◽  
Vol 7 (1) ◽  
pp. 115 ◽  
Author(s):  
Yunliang Meng ◽  
Sulaimon Giwa ◽  
Uzo Anucha
Keyword(s):  
Racial Profiling ◽  
Negative Impact ◽  
Black Youth ◽  
White People ◽  
Neighbourhood Level ◽  
Neighbourhood Characteristics ◽  
The Relationship ◽  
Race And Place ◽  
Stop And Search

Our study investigated racial profiling of Black youth in Toronto and linked this racial profiling to urban disadvantage theory, which highlights neighbourhood-level processes. Our findings provide empirical evidence suggesting that because of racial profiling, Black youth are subject to disproportionately more stops for gun-, traffic-, drug-, and suspicious activity-related reasons. Moreover, they show that drug-related stop-and-searches of Black youth occur most excessively in neighbourhoods where more White people reside and are less disadvantaged, demonstrating that race-and-place profiling of Black youth exists in police stop-and-search practices. This study shows that the theoretical literature in sociology on neighbourhood characteristics can contribute to an understanding of the relationship between race and police stops in the context of neighbourhood. It also discusses the negative impact of racial profiling on Black youth.

Scales and Units

2018 ◽  
Author(s):  
Kathryn M. de Luna
Keyword(s):  
Language Change ◽  
Historical Linguistics ◽  
Bantu Languages ◽  
The North ◽  
First Case ◽  
Linguistic Evidence ◽  
River Region ◽  
History Of ◽  
Alternative Approaches

This chapter uses two case studies to explore how historians study language movement and change through comparative historical linguistics. The first case study stands as a short chapter in the larger history of the expansion of Bantu languages across eastern, central, and southern Africa. It focuses on the expansion of proto-Kafue, ca. 950–1250, from a linguistic homeland in the middle Kafue River region to lands beyond the Lukanga swamps to the north and the Zambezi River to the south. This expansion was made possible by a dramatic reconfiguration of ties of kinship. The second case study explores linguistic evidence for ridicule along the Lozi-Botatwe frontier in the mid- to late 19th century. Significantly, the units and scales of language movement and change in precolonial periods rendered visible through comparative historical linguistics bring to our attention alternative approaches to language change and movement in contemporary Africa.

Applications of random graphs

2017 ◽  
Author(s):  
A.C.C. Coolen ◽  
A. Annibale ◽  
E.S. Roberts
Keyword(s):  
Social Networks ◽  
Random Graphs ◽  
Interaction Network ◽  
Power Grids ◽  
Protein Protein Interaction ◽  
Topological Features ◽  
First Case ◽  
The Stability ◽  
Protein Protein Interaction Network

This chapter reviews graph generation techniques in the context of applications. The first case study is power grids, where proposed strategies to prevent blackouts have been tested on tailored random graphs. The second case study is in social networks. Applications of random graphs to social networks are extremely wide ranging – the particular aspect looked at here is modelling the spread of disease on a social network – and how a particular construction based on projecting from a bipartite graph successfully captures some of the clustering observed in real social networks. The third case study is on null models of food webs, discussing the specific constraints relevant to this application, and the topological features which may contribute to the stability of an ecosystem. The final case study is taken from molecular biology, discussing the importance of unbiased graph sampling when considering if motifs are over-represented in a protein–protein interaction network.

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