scholarly journals Modeling Kelvin‐Helmholtz Instability at the High‐Latitude Boundary Layer in a Global Magnetosphere Simulation

2021 ◽  
Author(s):  
A. T. Michael ◽  
K. A. Sorathia ◽  
V.G. Merkin ◽  
K. Nykyri ◽  
B. Burkholder ◽  
...  
Keyword(s):  
Boundary Layer ◽  
High Latitude ◽  
Helmholtz Instability

scholarly journals Recirculation of plasma sheet particles into the high-latitude boundary layer

1998 ◽  
Vol 103 (A11) ◽  
pp. 26521-26532 ◽  
Author(s):  
D. C. Delcourt ◽  
J.-A. Sauvaud
Keyword(s):  
Boundary Layer ◽  
High Latitude ◽  
Plasma Sheet

scholarly journals Channelling of high-latitude boundary-layer flow

2008 ◽  
Vol 15 (1) ◽  
pp. 33-52 ◽  
Author(s):  
N. Nawri ◽  
R. E. Stewart
Keyword(s):  
Boundary Layer ◽  
High Latitude ◽  
Large Scale ◽  
Dynamical Downscaling ◽  
Geostrophic Wind ◽  
Horizontal Wind ◽  
Stationary States ◽  
Prevailing Wind ◽  
Surface Winds ◽  
Variable Surface

Abstract. Due to the stability of the boundary-layer stratification, high-latitude winds over complex terrain are strongly affected by blocking and channelling effects. Consequently, at many low-lying communities in the Canadian Archipelago, including Cape Dorset and Iqaluit considered in this study, surface winds for the most part are from two diametrically opposed directions, following the orientation of the elevated terrain. Shifts between the two prevailing wind directions can be sudden and are associated with geostrophic wind directions within a well defined narrow range. To quantitatively investigate the role of large-scale pressure gradients and the quasi-geostrophic overlying flow, an idealised dynamical system for the evolution of channelled surface winds is derived from the basic equations of motion, in which stability of stationary along-channel wind directions is described as a function of the geostrophic wind. In comparison with long-term horizontal wind statistics at the two locations it is shown that the climatologically prevailing wind directions can be identified as stationary states of the idealised wind model, and that shifts between prevailing wind directions can be represented as stability transitions between these stationary states. In that sense, the prevailing local wind conditions can be interpreted as attracting states of the actual flow, with observed surface winds adjusting to a new stable direction as determined by the idealised system within 3–9 h. Over these time-scales and longer it is therefore advantageous to determine the relatively slow evolution of the observationally well-resolved large-scale pressure distribution, instead of modelling highly variable surface winds directly. The simplified model also offers a tool for dynamical downscaling of global climate simulations, and for determining future scenarios for local prevailing wind conditions. In particular, it allows an estimation of the sensitivity of local low-level winds to changes in the large-scale atmospheric circulation.

Nonlinear evolution of the Kelvin-Helmholtz instability in the high-latitude ionosphere

1988 ◽  
Vol 93 (A1) ◽  
pp. 137 ◽  
Author(s):  
M. J. Keskinen ◽  
H. G. Mitchell ◽  
J. A. Fedder ◽  
P. Satyanarayana ◽  
S. T. Zalesak ◽  
...  
Keyword(s):  
High Latitude ◽  
Nonlinear Evolution ◽  
Helmholtz Instability ◽  
High Latitude Ionosphere

The Layered Structure of the Winter Atmospheric Boundary Layer in the Interior of Alaska

2013 ◽  
Vol 52 (4) ◽  
pp. 953-973 ◽  
Author(s):  
John A. Mayfield ◽  
Gilberto J. Fochesatto
Keyword(s):  
Boundary Layer ◽  
Statistical Analysis ◽  
Atmospheric Boundary Layer ◽  
Layered Structure ◽  
High Latitude ◽  
Meteorological Conditions ◽  
Formation Mechanisms ◽  
Observation Data ◽  
Interior Alaska ◽  
Radiosonde Observation

AbstractThe high-latitude winter atmospheric boundary layer of interior Alaska continually exhibits a complex layered structure as a result of extreme meteorological conditions. In this paper the occurrence of elevated inversions (EI), surface-based inversions (SBI), and stratified layers in the sub-Arctic from January 2000 to December 2009 is reported. This statistical analysis is based on radiosonde observation data from the Fairbanks National Weather Service station complemented by Winter Boundary Layer Experiment observations in the period 2010–11. This study found that SBIs occurred 64% of the time. An SBI occurred in combination with one, two, three, or four simultaneous EIs 84.86%, 48.49%, 21.23%, and 7.99% of the time, respectively, in 2326 total cases. The calculated mean SBI height was 377 m; EIs occurred at 1231, 2125, 2720, and 3125 m, respectively. This analysis was able to discriminate between locally controlled inversion layers and synoptic-dependent inversions and to identify their formation mechanisms. It was found that, in the presence of an SBI layer, the first EI layer formed 35.8% of the time under anticyclonic conditions at a mean height of 1249 m and 22% of the time in warm-air-advection situations at a mean height of 1049 m. The remaining 23.4% resulted from combined synoptic situations, and 18.8% were unclassified.

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