Total Lightning Characteristics Relative to Radar and Satellite Observations of Oklahoma Mesoscale Convective Systems

Abstract The advent of regional very high frequency (VHF) Lightning Mapping Arrays (LMAs) makes it possible to begin analyzing trends in total lightning characteristics in ensembles of mesoscale convective systems (MCSs). Flash initiations observed by the Oklahoma LMA and ground strikes observed by the National Lightning Detection Network were surveyed relative to infrared satellite and base-scan radar reflectivity imagery for 30 mesoscale convective systems occurring over a 7-yr period. Total lightning data were available for only part of the life cycle of most MCSs, but well-defined peaks in flash rates were usually observed for MCSs having longer periods of data. The mean of the maximum 10-min flash rates for the ensemble of MCSs was 203 min−1 for total flashes and 41 min−1 for cloud-to-ground flashes (CGs). In total, 21% of flashes were CGs and 13% of CGs lowered positive charge to ground. MCSs with the largest maximum flash rates entered Oklahoma in the evening before midnight. All three MCSs entering Oklahoma in early morning after sunrise had among the smallest maximum flash rates. Flash initiations were concentrated in or near regions of larger reflectivity and colder cloud tops. The CG flash rates and total flash rates frequently evolved similarly, although the fraction of flashes striking ground usually increased as an MCS decayed. Total flash rates tended to peak approximately 90 min before the maximum area of the −52°C cloud shield, but closer in time to the maximum area of colder cloud shields. MCSs whose −52°C cloud shield grew faster tended to have larger flash rates.

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Total Lightning Signatures of Thunderstorm Intensity over North Texas. Part II: Mesoscale Convective Systems

Monthly Weather Review ◽

10.1175/mwr3483.1 ◽

2007 ◽

Vol 135 (10) ◽

pp. 3303-3324 ◽

Cited By ~ 16

Author(s):

Scott M. Steiger ◽

Richard E. Orville ◽

Lawrence D. Carey

Keyword(s):

Mesoscale Convective Systems ◽

Research Network ◽

Fort Worth ◽

Convective Systems ◽

Source Density ◽

Stratiform Region ◽

Straight Line ◽

Lightning Detection ◽

Mesoscale Convective ◽

Total Lightning

Abstract Total lightning data from the Lightning Detection and Ranging (LDAR II) research network in addition to cloud-to-ground flash data from the National Lightning Detection Network (NLDN) and data from the Dallas–Fort Worth, Texas, Weather Surveillance Radar-1988 Doppler (WSR-88D) station (KFWS) were examined from individual cells within mesoscale convective systems that crossed the Dallas–Fort Worth region on 13 October 2001, 27 May 2002, and 16 June 2002. LDAR II source density contours were comma shaped, in association with severe wind events within mesoscale convective systems (MCSs) on 13 October 2001 and 27 May 2002. This signature is similar to the radar reflectivity bow echo. The source density comma shape was apparent 15 min prior to a severe wind report and lasted more than 20 min during the 13 October storm. Consistent relationships between severe straight-line winds, radar, and lightning storm cell characteristics (e.g., lightning heights) were not found for cells within MCSs as was the case for severe weather in supercells in Part I of this study. Cell interactions within MCSs are believed to weaken these relationships as reflectivity and lightning from nearby storms contaminate the cells of interest. Another hypothesis for these weak relations is that system, not individual cell, processes are responsible for severe straight-line winds at the surface. Analysis of the total lightning structure of the 13 October 2001 MCS showed downward-sloping source density contours behind the main convective line into the stratiform region. This further supports a charge advection mechanism in developing the stratiform charge structure. Bimodal vertical source density distributions were observed within MCS convection close to the center of the LDAR II network, while the lower mode was not detected at increasing range.

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Mesoscale convective systems as a source of electromagnetic signals registered by ground-based system and DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) satellite

Annales Geophysicae ◽

10.5194/angeo-39-321-2021 ◽

2021 ◽

Vol 39 (2) ◽

pp. 321-326

Author(s):

Karol Martynski ◽

Jan Blecki ◽

Roman Wronowski ◽

Andrzej Kulak ◽

Janusz Mlynarczyk ◽

...

Keyword(s):

Low Frequency ◽

Field Measurements ◽

Mesoscale Convective Systems ◽

Atmospheric Conditions ◽

Very High Frequency ◽

Convective Systems ◽

Mesoscale Convective ◽

Electromagnetic Signals ◽

Electro Magnetic ◽

Atmospheric Discharges

Abstract. Mesoscale convective systems (MCSs) are especially visible in the summertime when there is an advection of warm maritime air from the west. Advection of air masses is enriched by water vapour, the source of which can be found over the Mediterranean Sea. In propitious atmospheric conditions, and thus significant convection, atmospheric instability or strong vertical thermal gradient leads to the development of strong thunderstorm systems. In this paper, we discuss one case of MCSs, which generated a significant amount of +CG (cloud-to-ground), −CG and intracloud (IC) discharges. We have focused on the ELF (extremely low frequency; < 1 kHz) electromagnetic field measurements, since they allow us to compute the charge moments of atmospheric discharges. Identification of the MCSs is a complex process, due to many variables which have to be taken into account. For our research, we took into consideration a few tools, such as cloud reflectivity, atmospheric soundings and data provided by PERUN (Polish system of the discharge localisation system), which operates in a very high frequency (VHF) range (113.5–114.5 MHz). Combining the above-described measurement systems and tools, we identified a MCS which occurred in Poland on 23 July 2009. Furthermore, it fulfilled our requirements since the thunderstorm crossed the path of the DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) overpass.

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Elucidating the Life Cycle of Warm-Season Mesoscale Convective Systems in Eastern China from the Himawari-8 Geostationary Satellite

Remote Sensing ◽

10.3390/rs12142307 ◽

2020 ◽

Vol 12 (14) ◽

pp. 2307

Author(s):

Dandan Chen ◽

Jianping Guo ◽

Dan Yao ◽

Zhe Feng ◽

Yanluan Lin

Keyword(s):

Life Cycle ◽

Large Scale ◽

Eastern China ◽

Warm Season ◽

Northern China ◽

Early Morning ◽

Geostationary Satellite ◽

Mesoscale Convective Systems ◽

Convective Systems ◽

Mesoscale Convective

The life cycle of mesoscale convective systems (MCSs) in eastern China is yet to be fully understood, mainly due to the lack of observations of high spatio-temporal resolution and objective methods. Here, we quantitatively analyze the properties of warm-season (from April to September of 2016) MCSs during their lifetimes using the Himawari-8 geostationary satellite, combined with ground-based radars and gauge measurements. Generally, the occurrence of satellite derived MCSs has a noon peak over the land and an early morning peak over the ocean, which is several hours earlier than the precipitation peak. The developing and dissipative stages are significantly longer as total durations of MCSs increase. Aided by three-dimensional radar mosaics, we find the fraction of convective cores over northern China is much lower when compared with those in central United States, indicating that the precipitation produced by broad stratiform clouds may be more important for northern China. When there exists a large amount of stratiform precipitation, it releases a large amount of latent heat and promotes the large-scale circulations, which favors the maintenance of MCSs. These findings provide quantitative results about the life cycle of warm-season MCSs in eastern China based on multiple data sources and large numbers of samples.

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Modeling the Flash Rate of Thunderstorms. Part I: Framework

Monthly Weather Review ◽

10.1175/mwr-d-10-05031.1 ◽

2011 ◽

Vol 139 (10) ◽

pp. 3093-3111 ◽

Cited By ~ 15

Author(s):

Johannes M. L. Dahl ◽

Hartmut Höller ◽

Ulrich Schumann

Keyword(s):

Radar Data ◽

Mesoscale Convective Systems ◽

New Approach ◽

Flash Rate ◽

Convective Systems ◽

Cloud Properties ◽

Lightning Detection ◽

Mesoscale Convective ◽

Lightning Discharges ◽

New Framework

Abstract In this study a straightforward theoretical approach to determining the flash rate in thunderstorms is presented. A two-plate capacitor represents the basic dipole charge structure of a thunderstorm, which is charged by the generator current and discharged by lightning. If the geometry of the capacitor plates, the generator-current density, and the lightning charge are known, and if charging and discharging are in equilibrium, then the flash rate is uniquely determined. To diagnose the flash rate of real-world thunderstorms using this framework, estimates of the required relationships between the predictor variables and observable cloud properties are provided. With these estimates, the flash rate can be parameterized. In previous approaches, the lightning rate has been set linearly proportional to the electrification rate (such as the storm’s generator power or generator current), which implies a constant amount of neutralization by lightning discharges (such as lightning energy or lightning charge). This leads to inconsistencies between these approaches. Within the new framework proposed here, the discharge strength is allowed to vary with storm geometry, which remedies the physical inconsistencies of the previous approaches. The new parameterization is compared with observations using polarimetric radar data and measurements from the lightning detection network, LINET. The flash rates of a broad spectrum of discrete thunderstorm cells are accurately diagnosed by the new approach, while the flash rates of mesoscale convective systems are overestimated.

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Megaflashes: Just How Long Can a Lightning Discharge Get?

Bulletin of the American Meteorological Society ◽

10.1175/bams-d-19-0033.1 ◽

2019 ◽

Vol 101 (1) ◽

pp. E73-E86 ◽

Cited By ~ 5

Author(s):

Walter A. Lyons ◽

Eric C. Bruning ◽

Tom A. Warner ◽

Donald R. MacGorman ◽

Samantha Edgington ◽

...

Keyword(s):

Lightning Discharge ◽

Convective System ◽

Lightning Flash ◽

Additional Tool ◽

Convective Systems ◽

Lightning Detection ◽

Central United States ◽

Mesoscale Convective ◽

Lightning Discharges ◽

Mapping Arrays

Abstract The existence of mesoscale lightning discharges on the order of 100 km in length has been known since the radar-based findings of Ligda in the mid-1950s. However, it took the discovery of sprites in 1989 to direct significant attention to horizontally extensive “megaflashes” within mesoscale convective systems (MCSs). More recently, 3D Lightning Mapping Arrays (LMAs) have documented sprite-initiating lightning discharges traversing several hundred kilometers. One such event in a 2007 Oklahoma MCS having an LMA-derived length of 321 km, has been certified by the WMO as the longest officially documented lightning flash. The new Geostationary Lightning Mapper (GLM) sensor on GOES-16/17 now provides an additional tool suited to investigating mesoscale lightning. On 22 October 2017, a quasi-linear convective system moved through the central United States. At 0513 UTC, the GLM indicated a lightning discharge originated in northern Texas, propagated north-northeast across Oklahoma, fortuitously traversed the Oklahoma LMA (OKLMA), and finally terminated in southeastern Kansas. This event is explored using the OKLMA, the National Lightning Detection Network (NLDN), and the GLM. The NLDN reported 17 positive cloud-to-ground flashes (+CGs), 23 negative CGs (−CGs), and 37 intracloud flashes (ICs) associated with this massive discharge, including two +CGs capable of inducing sprites, with others triggering upward lightning from tall towers. Combining all available data confirms the megaflash, which illuminated 67,845 km2, was at least 500 km long, greatly exceeding the current official record flash length. Yet even these values are being superseded as GLM data are further explored, revealing that such vast discharges may not be all that uncommon.

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Evaluating Diurnal and Semi-Diurnal Cycle of Precipitation in CMIP6 Models Using Satellite- and Ground-Based Observations

Journal of Climate ◽

10.1175/jcli-d-20-0639.1 ◽

2021 ◽

pp. 1-56

Author(s):

Shuaiqi Tang ◽

Peter Gleckler ◽

Shaocheng Xie ◽

Jiwoo Lee ◽

Min-Seop Ahn ◽

...

Keyword(s):

Boundary Layer ◽

Diurnal Cycle ◽

Climate Models ◽

Early Morning ◽

Mesoscale Convective Systems ◽

Convective Systems ◽

Ensemble Mean ◽

Mesoscale Convective ◽

Diurnal Cycle Of Precipitation

AbstractThe diurnal and semi-diurnal cycle of precipitation simulated from CMIP6 models during 1996-2005 are evaluated globally between 60°S and 60°N, as well as at ten selected locations representing three categories of diurnal cycle of precipitation: (1) afternoon precipitation over land, (2) early morning precipitation over ocean, and (3) nocturnal precipitation over land. Three satellite-based and two ground-based rainfall products are used to evaluate the climate models. Globally, the ensemble mean of CMIP6 models shows a diurnal phase of 3 to 4 hours earlier over land and 1 to 2 hours earlier over ocean, when compared with the latest satellite products. These biases are in line with what were found in previous versions of climate models but reduced compared to the CMIP5 ensemble mean. Analysis at the selected locations complimented with in-situ measurements further reinforces these results. Several CMIP6 models have shown a significant improvement in the diurnal cycle of precipitation compared to their CMIP5 counterparts, notably on delaying afternoon precipitation over land. This can be attributed to the use of more sophisticated convective parameterizations. Most models are still unable to capture the nocturnal peak associated with elevated convection and propagating mesoscale convective systems, with a few exceptions that allow convection to be initiated above the boundary layer to capture nocturnal elevated convection. We also quantify an encouraging consistency between the satellite- and ground-based precipitation measurements despite differing spatiotemporal resolutions and sampling periods, which provides confidence in using them to evaluate the diurnal and semi-diurnal cycle of precipitation in climate models.

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In Situ Initiation of East Pacific Easterly Waves in a Regional Model

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-16-0124.1 ◽

2017 ◽

Vol 74 (2) ◽

pp. 333-351 ◽

Cited By ~ 5

Author(s):

Adam V. Rydbeck ◽

Eric D. Maloney ◽

Ghassan J. Alaka

Keyword(s):

Wrf Model ◽

Warm Pool ◽

Early Morning ◽

Mesoscale Convective Systems ◽

Weather Research And Forecasting ◽

Easterly Waves ◽

Convective Systems ◽

East Pacific ◽

Mesoscale Convective

Abstract The in situ generation of easterly waves (EWs) in the east Pacific (EPAC) is investigated using the Weather Research and Forecasting (WRF) Model. The sensitivity of the model to the suppression of EW forcing by locally generated convective disturbances is examined. Specifically, local forcing of EWs is removed by reducing the terrain height in portions of Central and South America to suppress robust sources of diurnal convective variability, most notably in the Panama Bight. High terrain contributes to the initiation of mesoscale convective systems in the early morning that propagate westward into the EPAC warm pool. When such mesoscale convective systems are suppressed in the model, EW variance is significantly reduced. This result suggests that EPAC EWs can be generated locally in association with higher-frequency convective disturbances, and these disturbances are determined to be an important source of EPAC EW variability. However, EPAC EW variability is not completely eliminated in such sensitivity experiments, indicating the importance for other sources of EW forcing, namely, EWs propagating into the EPAC from West Africa. Examination of the EW vorticity budget in the model suggests that nascent waves are zonally elongated and amplified by horizontal advection and vertical stretching of vorticity. Changes in the mean state between the control run and simulation with reduced terrain height also complicate interpretation of the results.

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Composite Life Cycle of Maritime Tropical Mesoscale Convective Systems in Scatterometer and Microwave Satellite Observations

Journal of the Atmospheric Sciences ◽

10.1175/2008jas2746.1 ◽

2009 ◽

Vol 66 (1) ◽

pp. 199-208 ◽

Cited By ~ 37

Author(s):

Brian Mapes ◽

Ralph Milliff ◽

Jan Morzel

Keyword(s):

Life Cycle ◽

Large Scale ◽

Surface Wind ◽

Precipitable Water ◽

Satellite Observations ◽

Mesoscale Convective Systems ◽

Convective Systems ◽

Mesoscale Convective ◽

The Common ◽

Cloud Tops

Abstract This study examines scatterometer-observed surface wind divergence and vorticity, along with precipitable water (PW), across the life cycle of tropical maritime mesoscale convective systems (MCSs) as resolved in 0.5° data. Simple composites were constructed around first appearances of cold (<210 K) cloud tops in infrared (IR) data at 3-hourly resolution. Many thousands of such events from the tropical Indo-Pacific in 2000 were used. Composites of subpopulations were also constructed by subdividing the dataset according to IR event size and duration, as well as by prevailing values of PW and vorticity at a 5° scale. The composite MCS life cycle here spans about a day and covers a few hundred kilometers, with a remarkable sameness across subpopulations. Surface wind convergence and PW buildup lead cold cloud appearance by many hours. Afterward there are many hours of divergence, indicative of downdrafts. Contrary to motivating hypotheses, the strength of this divergence relative to convergence is scarcely different in humid and dry subpopulation composites. Normalized time series of composite vorticity show an evolution that seems consistent with vortex stretching by this convergence–divergence cycle, with peak vorticity near the end of the period of convergence (3 h prior to cold cloud appearance). In rotating conditions, the common 1-day MCS life cycle is superposed on large-scale mean vorticity and convergence, approximately in proportion, which appear to be well scale-separated (covering the whole of the 48-h and 5°–10° averages) and are as strong as or stronger than the MCS signature.

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