scholarly journals Baroclinic and orographic low-level jets in the atmospheric boundary layer over the Fram Strait and their influence on the atmosphere-ocean energy exchange

2018 ◽  
Author(s):  
Dmitry Gennadyevich Chechin ◽  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Energy Exchange ◽  
Fram Strait ◽  
Ocean Energy ◽  
Low Level ◽  
Low Level Jets

scholarly journals Wind–Temperature Regime and Wind Turbulence in a Stable Boundary Layer of the Atmosphere: Case Study

2020 ◽  
Vol 12 (6) ◽  
pp. 955 ◽  
Author(s):  
Viktor A. Banakh ◽  
Igor N. Smalikho ◽  
Andrey V. Falits
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Stable Boundary Layer ◽  
Richardson Number ◽  
Atmospheric Waves ◽  
Stable Boundary ◽  
Low Level ◽  
Wind Turbulence ◽  
Stable Atmospheric Boundary Layer ◽  
Low Level Jets

The paper presents the results of probing the stable atmospheric boundary layer in the coastal zone of Lake Baikal with a coherent Doppler wind lidar and a microwave temperature profiler. Two-dimensional height–temporal distributions of the wind velocity vector components, temperature, and parameters characterizing atmospheric stability and wind turbulence were obtained. The parameters of the low-level jets and the atmospheric waves arising in the stable boundary layer were determined. It was shown that the stable atmospheric boundary layer has an inhomogeneous fine scale layered structure characterized by strong variations of the Richardson number Ri. Layers with large Richardson numbers alternate with layers where Ri is less than the critical value of the Richardson number Ricr = 0.25. The channels of decreased stability, where the conditions are close to neutral stratification 0 < Ri < 0.25, arise in the zone of the low-level jets. The wind turbulence in the central part of the observed jets, where Ri > Ricr, is weak, increases considerably to the periphery of jets, at heights where Ri < Ricr. The turbulence may intensify at the appearance of internal atmospheric waves.

scholarly journals LABLE: A Multi-Institutional, Student-Led, Atmospheric Boundary Layer Experiment

2015 ◽  
Vol 96 (10) ◽  
pp. 1743-1764 ◽  
Author(s):  
P. Klein ◽  
T. A. Bonin ◽  
J. F. Newman ◽  
D. D. Turner ◽  
P. B. Chilson ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Great Plains ◽  
Low Cost ◽  
Lawrence Livermore National Laboratory ◽  
National Laboratory ◽  
Heterogeneous Terrain ◽  
Thermodynamic Structure ◽  
Low Level ◽  
Low Level Jets

Abstract This paper presents an overview of the Lower Atmospheric Boundary Layer Experiment (LABLE), which included two measurement campaigns conducted at the Atmospheric Radiation Measurement (ARM) Program Southern Great Plains site in Oklahoma during 2012 and 2013. LABLE was conducted as a collaborative effort between the University of Oklahoma (OU), the National Severe Storms Laboratory, Lawrence Livermore National Laboratory (LLNL), and the ARM program. LABLE can be considered unique in that it was designed as a multiphase, low-cost, multiagency collaboration. Graduate students served as principal investigators and took the lead in designing and conducting experiments aimed at examining boundary layer processes. The main objective of LABLE was to study turbulent phenomena in the lowest 2 km of the atmosphere over heterogeneous terrain using a variety of novel atmospheric profiling techniques. Several instruments from OU and LLNL were deployed to augment the suite of in situ and remote sensing instruments at the ARM site. The complementary nature of the deployed instruments with respect to resolution and height coverage provides a near-complete picture of the dynamic and thermodynamic structure of the atmospheric boundary layer. This paper provides an overview of the experiment including 1) instruments deployed, 2) sampling strategies, 3) parameters observed, and 4) student involvement. To illustrate these components, the presented results focus on one particular aspect of LABLE: namely, the study of the nocturnal boundary layer and the formation and structure of nocturnal low-level jets. During LABLE, low-level jets were frequently observed and they often interacted with mesoscale atmospheric disturbances such as frontal passages.

scholarly journals Turbulence, Low-Level Jets, and Waves in the Tyrrhenian Coastal Zone as Shown by Sodar

Atmosphere ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 28 ◽  
Author(s):  
Igor Petenko ◽  
Giampietro Casasanta ◽  
Simone Bucci ◽  
Margarita Kallistratova ◽  
Roberto Sozzi ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Atmospheric Boundary Layer ◽  
Vertical Wind ◽  
Land Breeze ◽  
Tyrrhenian Sea ◽  
Turbulent Layer ◽  
Low Level ◽  
Doppler Sodar ◽  
Low Level Jets

The characteristics of the vertical and temporal structure of the coastal atmospheric boundary layer are variable for different sites and are often not well known. Continuous monitoring of the atmospheric boundary layer was carried out close to the Tyrrhenian Sea, near Tarquinia (Italy), in 2015–2017. A ground-based remote sensing instrument (triaxial Doppler sodar) and in situ sensors (meteorological station, ultrasonic anemometer/thermometer, and net radiometer) were used to measure vertical wind velocity profiles, the thermal structure of the atmosphere, the height of the turbulent layer, turbulent heat and momentum fluxes in the surface layer, atmospheric radiation, and precipitation. Diurnal alternation of the atmospheric stability types governed by the solar cycle coupled with local sea/land breeze circulation processes is found to be variable and is classified into several main regimes. Low-level jets (LLJ) at heights of 100–300 m above the surface with maximum wind speed in the range of 5–18 m s−1 occur in land breezes, both during the night and early in the morning. Empirical relationships between the LLJ core wind speed characteristics and those near the surface are obtained. Two separated turbulent sub-layers, both below and above the LLJ core, are often observed, with the upper layer extending up to 400–600 m. Kelvin–Helmholtz billows associated with internal gravity–shear waves occurring in these layers present opposite slopes, in correspondence with the sign of vertical wind speed gradients. Our observational results provide a basis for the further development of theoretical and modelling approaches, taking into account the wave processes occurring in the atmospheric boundary layer at the land–sea interface.

Role of low-level jets and boundary-layer properties on the NBL budget technique

2005 ◽  
Vol 135 (1-4) ◽  
pp. 35-43 ◽  
Author(s):  
N. Mathieu ◽  
I.B. Strachan ◽  
M.Y. Leclerc ◽  
A. Karipot ◽  
E. Pattey
Keyword(s):  
Boundary Layer ◽  
Low Level ◽  
Low Level Jets

scholarly journals Summertime Low-Level Jets over the High-Latitude Arctic Ocean

2008 ◽  
Vol 47 (6) ◽  
pp. 1770-1784 ◽  
Author(s):  
Douglas O. ReVelle ◽  
E. Douglas Nilsson
Keyword(s):  
Boundary Layer ◽  
Eddy Viscosity ◽  
Low Level ◽  
Rayleigh Friction ◽  
Low Level Jets ◽  
Low Level Jet ◽  
Horizontal Momentum ◽  
Ocean Observations ◽  
Measured Wind Speed ◽  
Good Agreement

Abstract The application of a simple analytic boundary layer model developed by Thorpe and Guymer did not produce good agreement with observational data for oceanic low-level jet observations even though this model has worked well for the predictions of low-level jets over continental surfaces. This failure to properly predict the boundary layer wind maxima was very puzzling because more detailed numerical boundary layer models have properly predicted these low-level oceanic wind maxima. To understand the reasons for its failure to explain the ocean observations, the authors modified the frictional terms in the horizontal linear momentum equations of Thorpe and Guymer, using a standard eddy viscosity closure technique instead of the Rayleigh friction parameterization originally used. This improvement in the modeling of the dissipation terms, which has resulted in the use of an enhanced Rayleigh friction parameterization in the horizontal momentum equations, modified the boundary layer winds such that the continental predictions remained nearly identical to those predicted previously using the Thorpe and Guymer model while the oceanic predictions have now become more representative of the measured wind speed from recent Arctic expeditions.

scholarly journals Impact of the vertical mixing induced by low-level jets on boundary layer ozone concentration

2013 ◽  
Vol 70 ◽  
pp. 123-130 ◽  
Author(s):  
Xiao-Ming Hu ◽  
Petra M. Klein ◽  
Ming Xue ◽  
Fuqing Zhang ◽  
David C. Doughty ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Ozone Concentration ◽  
Vertical Mixing ◽  
Low Level ◽  
Low Level Jets ◽  
Boundary Layer Ozone
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