scholarly journals A case study of a low level jet during OPALE

2014 ◽  
Vol 14 (22) ◽  
pp. 31091-31109 ◽  
Author(s):  
H. Gallée ◽  
H. Barral ◽  
E. Vignon ◽  
C. Genthon
Keyword(s):  
Three Dimensional ◽  
East Antarctica ◽  
Low Level ◽  
Thermal Wind ◽  
Flat Terrain ◽  
Dimensional Version ◽  
Low Level Jet ◽  
Oxidant Production

Abstract. A case study of a low level jet during the OPALE (Oxidant Production over Antarctic Land and its Export) summer campaign is presented. It has been observed at Dome C (East Antarctica) and is simulated accurately by the three-dimensional version of the Modèle Atmosphérique Régional (MAR). It is found that this low level jet is not related to an episode of thermal wind, conforting that Dome C may be a~place where turbulence on flat terrain can be studied.

scholarly journals A case study of a low-level jet during OPALE

2015 ◽  
Vol 15 (11) ◽  
pp. 6237-6246 ◽  
Author(s):  
H. Gallée ◽  
H. Barral ◽  
E. Vignon ◽  
C. Genthon
Keyword(s):  
Three Dimensional ◽  
East Antarctica ◽  
Low Level ◽  
Thermal Wind ◽  
Flat Terrain ◽  
Dimensional Version ◽  
Low Level Jet ◽  
Oxidant Production

Abstract. A case study of a low-level jet (LLJ) during the OPALE (Oxidant Production over Antarctic Land and its Export) summer campaign is presented. It has been observed at Dome C (East Antarctica) and is simulated accurately by the three-dimensional version of the Modèle Atmosphérique Régional (MAR). It is found that this low-level jet is not related to an episode of thermal wind, suggesting that Dome C may be a place where turbulence on flat terrain can be studied.

scholarly journals A Climatology of the Mesoscale Environment Associated with Heavily Precipitating Events over a Northwestern Mediterranean Area

2012 ◽  
Vol 51 (3) ◽  
pp. 468-488 ◽  
Author(s):  
Didier Ricard ◽  
Véronique Ducrocq ◽  
Ludovic Auger
Keyword(s):  
Daily Precipitation ◽  
Flow Instability ◽  
Three Dimensional ◽  
Mediterranean Area ◽  
Mature Stage ◽  
Target Area ◽  
High Moisture ◽  
Low Level ◽  
Ridge Pattern ◽  
Low Level Jet

AbstractA climatological approach is developed to characterize the mesoscale environment in which heavily precipitating events (HPEs) grow over a mountainous Mediterranean area. This climatology that is based on three-dimensional variational data assimilation (3D-Var) mesoscale analyses is performed for a 5-yr period, considering cases with daily precipitation of >150 mm occurring over southern France during autumn. Different diagnostics are used to document the time evolution of mesoscale features associated with the HPEs for initiation, mature, and dissipation stages. To underline differences according to the location of precipitation, four subdomains are also considered: Languedoc-Roussillon, Cévennes-Vivarais, South Alps, and Corsica. Composite analyses show that these events are driven by some common features (slowly evolving trough–ridge pattern and diffluent midlevel flow). Instability and moisture are transported by the low-level jet (LLJ) toward the target area from their sources, which are located upstream over the Mediterranean Sea. Strong moisture convergence is located within the left exit of the LLJ. These parameters reach a maximum during the mature stage. During the life cycle of the HPEs, the low-level winds rotate clockwise. Composite analyses also show that the synoptic and mesoscale patterns can differ greatly as a function of the location of the precipitation. Indeed, the LLJ varies from southeasterly to southwesterly. The midlevel flow varies from southerly to southwesterly. The areas of high moisture and instability are stretched in different orientations. Long-lasting events are associated with a more pronounced quasi-stationary trough–ridge pattern, higher values of CAPE, a wetter troposphere, and faster LLJ. The most-heavily precipitating events are found to be in general associated with higher values of these parameters or with a low-level inflow that is closer to perpendicular to the relief.

A Modeling Study of a Low-Level Jet along the Yun-Gui Plateau in South China

2016 ◽  
Vol 55 (1) ◽  
pp. 41-60 ◽  
Author(s):  
Ming-Yang He ◽  
Hong-Bo Liu ◽  
Bin Wang ◽  
Da-Lin Zhang
Keyword(s):  
South China ◽  
Large Scale ◽  
Model Simulation ◽  
Three Dimensional ◽  
Radiative Heating ◽  
Horizontal Wind ◽  
Maximum Speed ◽  
Pressure System ◽  
Low Level ◽  
Low Level Jet

AbstractIn this study, the three-dimensional structures and diurnal evolution of a typical low-level jet (LLJ) with a maximum speed of 24 m s−1 occurring in the 850–800-hPa layer are examined using both large-scale analysis and a high-resolution model simulation. The LLJ occurred on the eastern foothills of the Yun-Gui Plateau in south China from 1400 LST 29 June to 1400 LST 30 June 2003. The effects of surface radiative heating, topography, and latent heat release on the development of the LLJ case are also studied. Results show that a western Pacific Ocean subtropical high and a low pressure system on the respective southeast and northwest sides of the LLJ provide a favorable large-scale mean pressure pattern for the LLJ development. The LLJ reaches its peak intensity at 850 hPa near 0200 LST with wind directions veering from southerly before sunset to southwesterly at midnight. A hodograph at the LLJ core shows a complete diurnal cycle of the horizontal wind with a radius of 5.5 m s−1. It is found that in an LLJ coordinates system the along-LLJ geostrophic component regulates the distribution and 65% of the intensity of LLJ, whereas the ageostrophic component contributes to the clockwise rotation, thus leading to the formation and weakening of the LLJ during night- and daytime, respectively. Numerical sensitivity experiments confirm the surface radiative heating as the key factor in determining the formation of the nocturnal LLJ. The existence of the Yun-Gui Plateau, and the downstream condensational heating along the mei-yu front play secondary roles in the LLJ formation.

scholarly journals Environment Associated with Deep Moist Convection under SALLJ Conditions: A Case Study

2010 ◽  
Vol 25 (3) ◽  
pp. 970-984 ◽  
Author(s):  
Paloma Borque ◽  
Paola Salio ◽  
Matilde Nicolini ◽  
Yanina García Skabar
Keyword(s):  
Frontal Zone ◽  
Mesoscale Convective Systems ◽  
South American ◽  
Moist Convection ◽  
Low Level ◽  
Convective Systems ◽  
Mesoscale Convective ◽  
Low Level Jet ◽  
Deep Moist Convection

Abstract The present work focuses on the study of the environmental conditions preceding the development of a group of subtropical mesoscale convective systems over central and northern Argentina on 6–7 February 2003 during the South American Low Level Jet Experiment. This period was characterized by an extreme northerly low-level flow along the eastern Andes foothills [South American low-level jet (SALLJ)]. The entire studied episode was dominated by the presence of a very unstable air mass over northern Argentina and a frontal zone near 40°S. The SALLJ generated an important destabilization of the atmosphere due to the strong humidity and differential temperature advection. Orography provided an extra lifting motion to the configuration of the regional wind field, which was efficient in forcing the initiation of convection. Once convection developed, it moved and regenerated in regions where the convective instability was horizontally homogeneous and stronger.

On the Formation of an Elevated Nocturnal Inversion Layer in the Presence of a Low-Level Jet: A Case Study

2012 ◽  
Vol 144 (3) ◽  
pp. 441-449 ◽  
Author(s):  
Jakob Kutsher ◽  
Nitsa Haikin ◽  
Avi Sharon ◽  
Eyal Heifetz
Keyword(s):  
Inversion Layer ◽  
Low Level ◽  
Low Level Jet ◽  
Nocturnal Inversion

A case study of a gravity wave induced by Amazon forest orography and low level jet generation

2021 ◽  
Vol 307 ◽  
pp. 108457
Author(s):  
Polari B. Corrêa ◽  
Cléo Q. Dias-Júnior ◽  
Daniela Cava ◽  
Matthias Sörgel ◽  
Santiago Botía ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Amazon Forest ◽  
Low Level ◽  
Low Level Jet ◽  
Wave Induced
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