Impact of a nocturnal low‐level jet on surface‐layer turbulent characteristics

2021 ◽  
Author(s):  
N. A. Brunsell ◽  
D. A. Rahn ◽  
D. B. Mechem
Keyword(s):  
Surface Layer ◽  
Low Level ◽  
Turbulent Characteristics ◽  
Low Level Jet

Understanding the influence of ENSO on the Great Plains low-level jet in CMIP5 models

2017 ◽  
Vol 51 (4) ◽  
pp. 1537-1558 ◽  
Author(s):  
James F. Danco ◽  
Elinor R. Martin
Keyword(s):  
Great Plains ◽  
Cmip5 Models ◽  
Low Level ◽  
Low Level Jet

scholarly journals Nocturnal Low-Level Jet in a Mountain Basin Complex. Part II: Transport and Diffusion of Tracer under Stable Conditions

2006 ◽  
Vol 45 (5) ◽  
pp. 740-753 ◽  
Author(s):  
Lisa S. Darby ◽  
K. Jerry Allwine ◽  
Robert M. Banta
Keyword(s):  
Surface Pressure ◽  
Salt Lake ◽  
Low Level ◽  
Stable Conditions ◽  
Basin Scale ◽  
Flow Features ◽  
Transport And Diffusion ◽  
Low Level Jet ◽  
The City ◽  
And Diffusion

Abstract Differences in nighttime transport and diffusion of sulfur hexafluoride (SF6) tracer in an urban complex-terrain setting (Salt Lake City, Utah) are investigated using surface and Doppler lidar wind data and large-scale surface pressure differences. Interacting scales of motion, as studied through the URBAN 2000 field program combined with the Vertical Transport and Mixing (VTMX) experiment, explained the differences in the tracer behavior during three separate intensive operating periods. With an emphasis on nighttime stable boundary layer conditions, these field programs were designed to study flow features responsible for the nighttime transport of airborne substances. This transport has implications for air quality, homeland security, and emergency response if the airborne substances are hazardous. The important flow features investigated included thermally forced canyon and slope flows and a low-level jet (LLJ) that dominated the basin-scale winds when the surface pressure gradient was weak. The presence of thermally forced flows contributed to the complexity and hindered the predictability of the tracer motion within and beyond the city. When organized thermally forced flows were present, the tracer tended to stay closer to the city for longer periods of time, even though a strong basin-scale LLJ did develop. When thermally forced flows were short lived or absent, the basin-scale low-level jet dominated the wind field and enhanced the transport of tracer material out of the city.

Response of the low‐level jet to precession and its implications for proxies of the Indian monsoon

2022 ◽  
Author(s):  
Chetankumar Jalihal ◽  
Jayaraman Srinivasan ◽  
Arindam Chakraborty
Keyword(s):  
Indian Monsoon ◽  
Low Level ◽  
Low Level Jet

scholarly journals Impact of enriched analyses on regional numerical forecasts over southeastern South America during SALLJEX

2014 ◽  
Vol 29 (3) ◽  
pp. 315-330
Author(s):  
Yanina García Skabar ◽  
Matilde Nicolini
Keyword(s):  
Data Assimilation ◽  
South America ◽  
Atmospheric Modeling ◽  
South American ◽  
The South ◽  
Low Level ◽  
Positive Effects ◽  
Accumulated Rainfall ◽  
Low Level Jet ◽  
The Impact

During the warm season 2002-2003, the South American Low-Level Jet Experiment (SALLJEX) was carried out in southeastern South America. Taking advantage of the unique database collected in the region, a set of analyses is generated for the SALLJEX period assimilating all available data. The spatial and temporal resolution of this new set of analyses is higher than that of analyses available up to present for southeastern South America. The aim of this paper is to determine the impact of assimilating data into initial fields on mesoscale forecasts in the region, using the Brazilian Regional Atmospheric Modeling System (BRAMS) with particular emphasis on the South American Low-Level Jet (SALLJ) structure and on rainfall forecasts. For most variables, using analyses with data assimilated as initial fields has positive effects on short term forecast. Such effect is greater in wind variables, but not significant in forecasts longer than 24 hours. In particular, data assimilation does not improve forecasts of 24-hour accumulated rainfall, but it has slight positive effects on accumulated rainfall between 6 and 12 forecast hours. As the main focus is on the representation of the SALLJ, the effect of data assimilation in its forecast was explored. Results show that SALLJ is fairly predictable however assimilating additional observation data has small impact on the forecast of SALLJ timing and intensity. The strength of the SALLJ is underestimated independently of data assimilation. However, Root mean square error (RMSE) and BIAS values reveal the positive effect of data assimilation up to 18-hours forecasts with a greater impact near higher topography.

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