The structure of internal gravity waves in the atmosphere from high resolution radar measurements

2005 ◽  
Author(s):  
E. Gossard ◽  
J. Richter ◽  
D. Atlas
Keyword(s):  
High Resolution ◽  
Gravity Waves ◽  
Internal Gravity Waves ◽  
High Resolution Radar ◽  
Radar Measurements

scholarly journals High-resolution Beijing mesosphere–stratosphere–troposphere (MST) radar detection of tropopause structure and variability over Xianghe (39.75° N, 116.96° E), China

2019 ◽  
Vol 37 (4) ◽  
pp. 631-643 ◽  
Author(s):  
Feilong Chen ◽  
Gang Chen ◽  
Yufang Tian ◽  
Shaodong Zhang ◽  
Kaiming Huang ◽  
...  
Keyword(s):  
High Resolution ◽  
Correlation Coefficient ◽  
Potential Vorticity ◽  
Specular Reflection ◽  
Lapse Rate ◽  
Stable Layer ◽  
Mst Radar ◽  
High Resolution Radar ◽  
Radar Measurements ◽  
Dynamical Potential

Abstract. As a result of partial specular reflection from the atmospheric stable layer, the radar tropopause (RT) can simply and directly be detected by VHF radars with vertical incidence. Here, the Beijing mesosphere–stratosphere–troposphere (MST) radar measurements are used to investigate the structure and the variabilities in the tropopause in Xianghe, China, with a temporal resolution of 0.5 h from November 2011 to May 2017. The high-resolution radar-derived tropopause is compared with the thermal lapse-rate tropopause (LRT) that is defined by the World Meteorological Organization (WMO) criterion from twice-daily radiosonde soundings and with the dynamical potential vorticity tropopause (PVT) that is defined as the height of the 2 PVU (PVU – potential vorticity units; 1 PVU = 106 m2 s−1 K kg−1) surface. We only consider tropopauses below 16 km in this study because of limitations with the radar system. During all the seasons, the RT and the LRT in altitude agree well with each other, with a correlation coefficient of ≥0.74. Statistically, weaker (higher) tropopause sharpness seems to contribute to larger (smaller) difference between the RT and the LRT in altitude. The RT agrees well with the PVT in altitude during winter and spring, with a correlation coefficient of ≥0.72, while the correlation coefficient in summer is only 0.33. As expected, the monthly mean RT and LRT height both show seasonal variations. Lomb–Scargle periodograms show that the tropopause exhibits obvious diurnal variation throughout the seasons, whereas the semidiurnal oscillations are rare and are occasionally observed during summer and later spring. Our study shows the potential of the Beijing MST radar to determine the tropopause height as well as present its diurnal oscillations.

On the formation and propagation of nonlinear internal boluses across a shelf break

2007 ◽  
Vol 577 ◽  
pp. 137-159 ◽  
Author(s):  
SUBHAS K. VENAYAGAMOORTHY ◽  
OLIVER B. FRINGER
Keyword(s):  
High Resolution ◽  
Gravity Waves ◽  
Three Dimensional ◽  
Internal Gravity Waves ◽  
Gravity Currents ◽  
Interaction Process ◽  
Shelf Break ◽  
Ambient Fluid ◽  
Dense Fluid ◽  
Incident Waves

High-resolution two- and three-dimensional numerical simulations are performed of first-mode internal gravity waves interacting with a shelf break in a linearly stratified fluid. The interaction of nonlinear incident waves with the shelf break results in the formation of upslope-surging vortex cores of dense fluid (referred to here as internal boluses) that propagate onto the shelf. This paper primarily focuses on understanding the dynamics of the interaction process with particular emphasis on the formation, structure and propagation of internal boluses onshelf. A possible mechanism is identified for the excitation of vortex cores that are lifted over the shelf break, from where (from the simplest viewpoint) they essentially propagate as gravity currents into a linearly stratified ambient fluid.

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