Lightning activity related to satellite and radar observations of a mesoscale convective system over Texas on 7–8 April 2002

Abstract. Deployed on the mountainous island of Corsica for thunderstorm monitoring purposes in the Mediterranean Basin, SAETTA is a network of 12 LMA (Lightning Mapping Array, designed by New Mexico Tech, USA) stations that allows the 3-D mapping of very high-frequency (VHF) radiation emitted by cloud discharges in the 60–66 MHz band. It works at high temporal (∼40 ns in each 80 µs time window) and spatial (tens of meters at best) resolution within a range of about 350 km. Originally deployed in May 2014, SAETTA was commissioned during the summer and autumn seasons and has now been permanently operational since April 2016 until at least the end of 2020. We first evaluate the performances of SAETTA through the radial, azimuthal, and altitude errors of VHF source localization with the theoretical model of Thomas et al. (2004). We also compute on a 240 km × 240 km domain the minimum altitude at which a VHF source can be detected by at least six stations by taking into account the masking effect of the relief. We then report the 3-year observations on the same domain in terms of number of lightning days per square kilometer (i.e., total number of days during which lightning has been detected in a given 1 km square pixel) and in terms of lightning days integrated across the domain. The lightning activity is first maximum in June because of daytime convection driven by solar energy input, but concentrates on a specific hot spot in July just above the intersection of the three main valleys. This hot spot is probably due to the low-level convergence of moist air fluxes from sea breezes channeled by the three valleys. Lightning activity increases again in September due to numerous small thunderstorms above the sea and to some high-precipitation events. Finally we report lightning observations of unusual high-altitude discharges associated with the mesoscale convective system of 8 June 2015. Most of them are small discharges on top of an intense convective core during convective surges. They are considered in the flash classification of Thomas et al. (2003) to be small–isolated and short–isolated flashes. The other high-altitude discharges, much less numerous, are long-range flashes that develop through the stratiform region and suddenly undergo upward propagations towards an uppermost thin layer of charge. This latter observation is apparently consistent with the recent conceptual model of Dye and Bansemer (2019) that explains such an upper-level layer of charge in the stratiform region by the development of a non-riming ice collisional charging in a mesoscale updraft.

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Investigation of Cloud Microphysical Features During the Passage of a Tropical Mesoscale Convective System: Numerical Simulations and X-Band Radar Observations

Pure and Applied Geophysics ◽

10.1007/s00024-020-02622-w ◽

2021 ◽

Author(s):

Subrata Kumar Das ◽

Anupam Hazra ◽

Sachin M. Deshpande ◽

U. V. Murali Krishna ◽

Yogesh K. Kolte

Keyword(s):

Numerical Simulations ◽

Mesoscale Convective System ◽

Convective System ◽

Radar Observations ◽

X Band ◽

Mesoscale Convective

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Evolution of the total lightning activity in a leading-line and trailing stratiform mesoscale convective system over Beijing

Advances in Atmospheric Sciences ◽

10.1007/s00376-010-0001-8 ◽

2011 ◽

Vol 28 (4) ◽

pp. 866-878 ◽

Cited By ~ 29

Author(s):

Dongxia Liu ◽

Xiushu Qie ◽

Yajun Xiong ◽

Guili Feng

Keyword(s):

Mesoscale Convective System ◽

Lightning Activity ◽

Convective System ◽

Mesoscale Convective ◽

Total Lightning

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Multiscale EnKF Assimilation of Radar and Conventional Observations and Ensemble Forecasting for a Tornadic Mesoscale Convective System

Monthly Weather Review ◽

10.1175/mwr-d-13-00262.1 ◽

2015 ◽

Vol 143 (4) ◽

pp. 1035-1057 ◽

Cited By ~ 41

Author(s):

Nathan Snook ◽

Ming Xue ◽

Youngsun Jung

Keyword(s):

Surface Wind ◽

Mesoscale Convective System ◽

Radar Data ◽

Precipitation Forecast ◽

Lateral Boundary Condition ◽

Convective System ◽

Near Surface ◽

Radar Observations ◽

Probabilistic Forecasts ◽

Mesoscale Convective

Abstract In recent studies, the authors have successfully demonstrated the ability of an ensemble Kalman filter (EnKF), assimilating real radar observations, to produce skillful analyses and subsequent ensemble-based probabilistic forecasts for a tornadic mesoscale convective system (MCS) that occurred over Oklahoma and Texas on 9 May 2007. The current study expands upon this prior work, performing experiments for this case on a larger domain using a nested-grid EnKF, which accounts for mesoscale uncertainties through the initial ensemble and lateral boundary condition perturbations. In these new experiments, conventional observations (including surface, wind profiler, and upper-air observations) are assimilated in addition to the WSR-88D and the Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) radar data used in the previous studies, better representing meso- and convective-scale features. The relative impacts of conventional and radar data on analyses and forecasts are examined, and biases within the ensemble are investigated. The new experiments produce a substantially improved forecast, including better representation of the convective lines of the MCS. Assimilation of radar data substantially improves the ensemble precipitation forecast. Assimilation of conventional data together with radar observations substantially improves the forecast of near-surface mesovortices within the MCS, improves forecasts of surface temperature and dewpoint, and imparts a slight but noticeable improvement to short-term precipitation forecasts. Furthermore, ensemble analyses and forecasts are found to be sensitive to the localization radius applied to conventional data within the EnKF.

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High temporal resolution VHF radar observations of stratospheric air intrusions in to the upper troposphere during the passage of a mesoscale convective system over Gadanki (13.5° N, 79.2° E)

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-13843-2009 ◽

2009 ◽

Vol 9 (3) ◽

pp. 13843-13857 ◽

Cited By ~ 2

Author(s):

K. K. Kumar ◽

K. N. Uma

Keyword(s):

Temporal Resolution ◽

Mesoscale Convective System ◽

Rain Gauge ◽

High Temporal Resolution ◽

Convective System ◽

Vhf Radar ◽

Radar Observations ◽

Time Section ◽

Upper Troposphere ◽

Mesoscale Convective

Abstract. A high temporal resolution VHF radar experiment, which was carried out to divulge the clear-air structure of a mesoscale convective system (MCS) at fine time scales over Gadanki, is discussed. The VHF radar was continuously operated for four hours with 11 seconds time resolution on 19 June 2006, which facilitated the study of finer details of stratospheric air intrusions into the upper troposphere during the passage of a MCS. Simultaneous GPS sonde and ground based optical rain gauge measurements are also used for the present study along with radar observations. The height-time section of range corrected signal to noise ratio (RSNR) revealed the convective cells reaching as high as 14 km altitude and the signature of the tropopause as a layered structure at around 16.5 km. The important observation from the radar RSNR is the time localized inclined echoes in the height region of 12–16 km region giving evidence for stratospheric air intrusion into the upper troposphere. Further, this observation is confirmed by the height–time section of vertical velocity, which showed the intense downdraughts in the height region of inclined radar echoes. A detailed examination of this down draft revealed an episode of high frequency gravity wave excitation, which is believed to be the consequence of intrusion of stable stratospheric air into the upper troposphere. Thus, the present study brings out for the first time, how the stratospheric intrusions will appear in the radar height-time sections and the consequences of such intrusions in the upper troposphere

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Ensemble Probabilistic Prediction of a Mesoscale Convective System and Associated Polarimetric Radar Variables Using Single-Moment and Double-Moment Microphysics Schemes and EnKF Radar Data Assimilation

Monthly Weather Review ◽

10.1175/mwr-d-16-0162.1 ◽

2017 ◽

Vol 145 (6) ◽

pp. 2257-2279 ◽

Cited By ~ 12

Author(s):

Bryan J. Putnam ◽

Ming Xue ◽

Youngsun Jung ◽

Nathan A. Snook ◽

Guifu Zhang

Keyword(s):

Mesoscale Convective System ◽

Radar Data ◽

Convective Precipitation ◽

Convective System ◽

Ensemble Forecasts ◽

Verification Methods ◽

Probabilistic Forecasts ◽

Mesoscale Convective ◽

Single Moment ◽

Double Moment

Abstract Ensemble-based probabilistic forecasts are performed for a mesoscale convective system (MCS) that occurred over Oklahoma on 8–9 May 2007, initialized from ensemble Kalman filter analyses using multinetwork radar data and different microphysics schemes. Two experiments are conducted, using either a single-moment or double-moment microphysics scheme during the 1-h-long assimilation period and in subsequent 3-h ensemble forecasts. Qualitative and quantitative verifications are performed on the ensemble forecasts, including probabilistic skill scores. The predicted dual-polarization (dual-pol) radar variables and their probabilistic forecasts are also evaluated against available dual-pol radar observations, and discussed in relation to predicted microphysical states and structures. Evaluation of predicted reflectivity (Z) fields shows that the double-moment ensemble predicts the precipitation coverage of the leading convective line and stratiform precipitation regions of the MCS with higher probabilities throughout the forecast period compared to the single-moment ensemble. In terms of the simulated differential reflectivity (ZDR) and specific differential phase (KDP) fields, the double-moment ensemble compares more realistically to the observations and better distinguishes the stratiform and convective precipitation regions. The ZDR from individual ensemble members indicates better raindrop size sorting along the leading convective line in the double-moment ensemble. Various commonly used ensemble forecast verification methods are examined for the prediction of dual-pol variables. The results demonstrate the challenges associated with verifying predicted dual-pol fields that can vary significantly in value over small distances. Several microphysics biases are noted with the help of simulated dual-pol variables, such as substantial overprediction of KDP values in the single-moment ensemble.

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