Case Studies on Concentric Gravity Waves Source using Lightning Flash Rate, Brightness Temperature and Backward Ray Tracing at São Martinho da Serra (29.44°S, 53.82°W)

2021 ◽  
Author(s):  
P. K. Nyassor ◽  
C. M. Wrasse ◽  
D. Gobbi ◽  
I. Paulino ◽  
S. L. Vadas ◽  
...  
Keyword(s):  
Brightness Temperature ◽  
Case Studies ◽  
Ray Tracing ◽  
Gravity Waves ◽  
Lightning Flash ◽  
Flash Rate

Three Years of TRMM Precipitation Features. Part I: Radar, Radiometric, and Lightning Characteristics

2005 ◽  
Vol 133 (3) ◽  
pp. 543-566 ◽  
Author(s):  
Daniel J. Cecil ◽  
Steven J. Goodman ◽  
Dennis J. Boccippio ◽  
Edward J. Zipser ◽  
Stephen W. Nesbitt
Keyword(s):  
Brightness Temperature ◽  
Tropical Rainfall Measuring Mission ◽  
Radar Reflectivity ◽  
Lightning Flash ◽  
Frequency Of Occurrence ◽  
Areal Extent ◽  
Flash Rate ◽  
Brightness Temperatures ◽  
Rate Minimum ◽  
Trmm Precipitation

Abstract During its first three years, the Tropical Rainfall Measuring Mission (TRMM) satellite observed nearly six million precipitation features. The population of precipitation features is sorted by lightning flash rate, minimum brightness temperature, maximum radar reflectivity, areal extent, and volumetric rainfall. For each of these characteristics, essentially describing the convective intensity or the size of the features, the population is broken into categories consisting of the top 0.001%, top 0.01%, top 0.1%, top 1%, top 2.4%, and remaining 97.6%. The set of “weakest/smallest” features composes 97.6% of the population because that fraction does not have detected lightning, with a minimum detectable flash rate of 0.7 flashes (fl) min−1. The greatest observed flash rate is 1351 fl min−1; the lowest brightness temperatures are 42 K (85 GHz) and 69 K (37 GHz). The largest precipitation feature covers 335 000 km2, and the greatest rainfall from an individual precipitation feature exceeds 2 × 1012 kg h−1 of water. There is considerable overlap between the greatest storms according to different measures of convective intensity. The largest storms are mostly independent of the most intense storms. The set of storms producing the most rainfall is a convolution of the largest and the most intense storms. This analysis is a composite of the global Tropics and subtropics. Significant variability is known to exist between locations, seasons, and meteorological regimes. Such variability will be examined in Part II. In Part I, only a crude land–ocean separation is made. The known differences in bulk lightning flash rates over land and ocean result from at least two differences in the precipitation feature population: the frequency of occurrence of intense storms and the magnitude of those intense storms that do occur. Even when restricted to storms with the same brightness temperature, same size, or same radar reflectivity aloft, the storms over water are considerably less likely to produce lightning than are comparable storms over land.

Forward ray-tracing for medium-scale gravity waves observed during the COPEX campaign

2012 ◽  
Vol 90-91 ◽  
pp. 117-123 ◽  
Author(s):  
I. Paulino ◽  
H. Takahashi ◽  
S.L. Vadas ◽  
C.M. Wrasse ◽  
J.H.A. Sobral ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Gravity Waves ◽  
Medium Scale

INVESTIGATION OF RADAR AND ELECTRICAL CHARACTERISTICS OF THUNDERCLOUDS SEEDED WITH A GLACIOGENIC REAGENT IN KARNATAKA, INDIA

2021 ◽  
pp. 112-122
Author(s):  
A.A. SIN'KEVICH ◽  
◽  
B. BOE ◽  
S. PAWAR ◽  
YU. P. MIKHAILOVSKII ◽  
...  
Keyword(s):  
Network Data ◽  
Lightning Flash ◽  
Electrical Characteristics ◽  
North Caucasus ◽  
Flash Rate ◽  
Convective Clouds ◽  
The North ◽  
Lightning Detection ◽  
Karnataka State ◽  
Order Of Magnitude

Characteristics of developing convective clouds (Cu) in Karnataka state (India) during the thunderstorm formation are analyzed using weather radar and lightning detection network data. It is noted that radar characteristics of Cu which produced lightning, exceed those where lightning does not form. The study has shown that the number of negative cloud-to-ground strokes exceeds the number of positive ones by an order of magnitude. The radar characteristics of clouds in India and the North Caucasus are compared. Significant differences in lightning flash rates over the mentioned regions are registered. A low correlation is found between the supercooled volume and the flash rate of negative lightning. The paper also presents the results of studying the dynamic characteristics of four Cu seeded with a glaciogenic reagent. The thunderstorm risk is estimated for the clouds. It is shown that the seeding increases a probability of lightning events.

scholarly journals Forecasting Lightning Threat Using Cloud-Resolving Model Simulations

2009 ◽  
Vol 24 (3) ◽  
pp. 709-729 ◽  
Author(s):  
Eugene W. McCaul ◽  
Steven J. Goodman ◽  
Katherine M. LaCasse ◽  
Daniel J. Cecil
Keyword(s):  
Numerical Models ◽  
Wrf Model ◽  
Phase Region ◽  
General Character ◽  
Lightning Flash ◽  
Flash Rate ◽  
Spatial Coverage ◽  
Physically Based ◽  
Cloud Resolving Model ◽  
Near Term

Abstract Two new approaches are proposed and developed for making time- and space-dependent, quantitative short-term forecasts of lightning threats, and a blend of these approaches is devised that capitalizes on the strengths of each. The new methods are distinctive in that they are based entirely on the ice-phase hydrometeor fields generated by regional cloud-resolving numerical simulations, such as those produced by the Weather Research and Forecasting (WRF) model. These methods are justified by established observational evidence linking aspects of the precipitating ice hydrometeor fields to total flash rates. The methods are straightforward and easy to implement, and offer an effective near-term alternative to the incorporation of complex and costly cloud electrification schemes into numerical models. One method is based on upward fluxes of precipitating ice hydrometeors in the mixed-phase region at the −15°C level, while the second method is based on the vertically integrated amounts of ice hydrometeors in each model grid column. Each method can be calibrated by comparing domain-wide statistics of the peak values of simulated flash-rate proxy fields against domain-wide peak total lightning flash-rate density data from observations. Tests show that the first method is able to capture much of the temporal variability of the lightning threat, while the second method does a better job of depicting the areal coverage of the threat. The blended solution proposed in this work is designed to retain most of the temporal sensitivity of the first method, while adding the improved spatial coverage of the second. Simulations of selected diverse North Alabama cases show that the WRF can distinguish the general character of most convective events, and that the methods employed herein show promise as a means of generating quantitatively realistic fields of lightning threat. However, because the models tend to have more difficulty in predicting the instantaneous placement of storms, forecasts of the detailed location of the lightning threat based on single simulations can be in error. Although these model shortcomings presently limit the precision of lightning threat forecasts from individual runs of current generation models, the techniques proposed herein should continue to be applicable as newer and more accurate physically based model versions, physical parameterizations, initialization techniques, and ensembles of forecasts become available.

The breaking of transient inertio-gravity waves in a shear flow using the Gaussian beam approximation

2014 ◽  
Vol 759 ◽  
pp. 676-700 ◽  
Author(s):  
C. Rodas ◽  
M. Pulido
Keyword(s):  
Shear Flow ◽  
Gaussian Beam ◽  
Ray Tracing ◽  
Gravity Waves ◽  
Convective Instability ◽  
Shear Flows ◽  
Computational Cost ◽  
Dynamical Instability ◽  
Initial Time ◽  
Instability Criterion

AbstractThe propagation of transient inertio-gravity waves in a shear flow is examined using the Gaussian beam formulation. This formulation assumes Gaussian wavepackets in the spectral space and uses a second-order Taylor expansion of the phase of the wave field. In this sense, the Gaussian beam formulation is also an asymptotic approximation like spatial ray tracing; however, the first one is free of the singularities found in spatial ray tracing at caustics. Therefore, the Gaussian beam formulation permits the examination of the evolution of transient inertio-gravity wavepackets from the initial time up to the destabilization of the flow close to the critical levels. We show that the transience favours the development of the dynamical instability relative to the convective instability. In particular, there is a well-defined threshold for which small initial amplitude transient inertio-gravity waves never reach the convective instability criterion. This threshold does not exist for steady-state inertio-gravity waves for which the wave amplitude increases indefinitely towards the critical level. The Gaussian beam formulation is shown to be a powerful tool to treat analytically several aspects of inertio-gravity waves in simple shear flows. In more realistic shear flows, its numerical implementation is readily available and the required numerical calculations have a low computational cost.

A Parametrization for Triad Interactions of Internal Gravity Waves in Varying Background Flows for WKBJ Ray-Tracing Methods

2020 ◽  
Author(s):  
Georg Sebastian Voelker ◽  
Triantaphyllos Akylas ◽  
Ulrich Achatz
Keyword(s):  
Ray Tracing ◽  
Gravity Waves ◽  
Energy Transport ◽  
Multiple Scale ◽  
Internal Gravity Waves ◽  
Quantitative Agreement ◽  
Mean Flow ◽  
Wave Trains ◽  
The Impact ◽  
Triad Interactions

<p>Internal gravity waves are a well known mechanism of energy transport in stratified fluids such as the atmosphere and the ocean. Their abundance and importance for various geophysical processes like ocean mixing and momentum deposition in atmospheric jets are widely accepted. While resonant wave-wave interactions of monochromatic disturbances have received intensive study, little work has been done on triad interactions between wave trains that are modulated by a variable mean flow.</p><p>Using the method of multiple scale asymptotics we consider a weakly non-linear Boussinesq WKBJ theory for interacting gravity wave trains propagating through a finite amplitude background flow. Consequently the wave trains are allowed to spectrally pass through resonance conditions and exchange energy when sufficiently close to resonance. We find a global optimal threshold for the deviation from resonance and derive a corresponding parametrization for the triad interaction applicable to ray tracing schemes.</p><p>We test the theory with idealized simulations in which two wave trains generate a third by passing through resonance in a sinusoidal background shear flow with varying vertical scales. Comparing WKBJ simulations with wave resolving large eddy simulations we find qualitative and quantitative agreement. Furthermore we assess the impact of the strength of the modulation as well as the effect of the wave amplitudes on the energy exchange between the interacting wave triad.</p>

scholarly journals Case studies of nonorographic gravity waves over the Southern Ocean emphasize the role of moisture

2015 ◽  
Vol 120 (4) ◽  
pp. 1278-1299 ◽  
Author(s):  
Riwal Plougonven ◽  
Albert Hertzog ◽  
M. Joan Alexander
Keyword(s):  
Southern Ocean ◽  
Case Studies ◽  
Gravity Waves
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