scholarly journals Evolution of Lightning Activity and Storm Charge Relative to Dual-Doppler Analysis of a High-Precipitation Supercell Storm

2013 ◽  
Vol 141 (7) ◽  
pp. 2199-2223 ◽  
Author(s):  
Kristin M. Calhoun ◽  
Donald R. MacGorman ◽  
Conrad L. Ziegler ◽  
Michael I. Biggerstaff
Keyword(s):  
Spatial Distribution ◽  
Electric Potential ◽  
Short Distance ◽  
The Core ◽  
Supercell Storm ◽  
Mapping Array ◽  
Lightning Leader ◽  
High Precipitation ◽  
Horizontal Layers ◽  
Doppler Analysis

Abstract A high-precipitation tornadic supercell storm was observed on 29–30 May 2004 during the Thunderstorm Electrification and Lightning Experiment. Observational systems included the Oklahoma Lightning Mapping Array, mobile balloon-borne soundings, and two mobile C-band radars. The spatial distribution and evolution of lightning are related to storm kinematics and microphysics, specifically through regions of microphysical charging and the location and geometry of those charge regions. Lightning flashes near the core of this storm were extraordinarily frequent, but tended to be of shorter duration and smaller horizontal extent than typical flashes elsewhere. This is hypothesized to be due to the charge being in many small pockets, with opposite polarities of charge close together in adjoining pockets. Thus, each polarity of lightning leader could propagate only a relatively short distance before reaching regions of unfavorable electric potential. In the anvil, however, lightning extended tens of kilometers from the reflectivity cores in roughly horizontal layers, consistent with the charge spreading through the anvil in broad sheets. The strong, consistent updraft of this high-precipitation supercell storm combined with the large hydrometeor concentrations to produce the extremely high flash rates observed during the analysis period. The strength and size of the updraft also contributed to unique lightning characteristics such as the transient hole of reduced lightning density and discharges in the overshooting top.

scholarly journals Lightning in the Anvils of Supercell Thunderstorms

2012 ◽  
Vol 140 (7) ◽  
pp. 2064-2079 ◽  
Author(s):  
Stephanie A. Weiss ◽  
Donald R. MacGorman ◽  
Kristin M. Calhoun
Keyword(s):  
Warm Season ◽  
Opposite Polarity ◽  
Layer Charge ◽  
Supercell Storm ◽  
Lightning Detection ◽  
Supercell Storms ◽  
Mapping Array ◽  
Storm Dynamics ◽  
Supercell Thunderstorms

Abstract This study uses data from the Oklahoma Lightning Mapping Array (OK-LMA), the National Lightning Detection Network, and the Norman, Oklahoma (KOUN), prototype Weather Surveillance Radar-1988 Doppler (WSR-88D) radar to examine the evolution and structure of lightning in the anvils of supercell storms as they relate to storm dynamics and microphysics. Several supercell storms within the domain of the OK-LMA were examined to determine whether they had lightning in the anvil region, and if so, the time and location of the initiation of the anvil flashes were determined. Every warm-season supercell storm had some flashes that were initiated in or near the stronger reflectivities of the parent storm and propagated 40–70 km downstream to penetrate well into the anvil. Some supercell storms also had flashes that were initiated within the anvil itself, 40–100 km beyond the closest 30-dBZ contour of the storm. These flashes were typically initiated in one of three locations: 1) coincident with a local reflectivity maximum, 2) between the uppermost storm charge and a screening-layer charge of opposite polarity near the cloud boundary, or 3) in a region in which the anvils from two adjoining storms intersected. In some storms, anvil flashes struck ground beneath a reflectivity maximum in which reflectivity ≥20 dBZ had extended below the 0°C isotherm, possibly leading to the formation of embedded convection. This relationship may be useful for identifying regions in which there is a heightened risk for cloud-to-ground strikes beneath anvil clouds. In one storm, however, anvil lightning struck ground even though this reflectivity signature was absent.

scholarly journals Parasitic infection reduces dispersal of ciliate host

2010 ◽  
Vol 7 (3) ◽  
pp. 327-329 ◽  
Author(s):  
Simon Fellous ◽  
Elsa Quillery ◽  
Alison B. Duncan ◽  
Oliver Kaltz
Keyword(s):  
Population Structure ◽  
Spatial Distribution ◽  
Short Distance ◽  
Parasitic Infection ◽  
Genetic Population Structure ◽  
Paramecium Caudatum ◽  
Dispersal Capacity ◽  
Genetic Population ◽  
Social Aggregation ◽  
Aggregation Behaviour

Parasitic infection can modify host mobility and consequently their dispersal capacity. We experimentally investigated this idea using the ciliate Paramecium caudatum and its bacterial parasite Holospora undulata . We compared the short-distance dispersal of infected and uninfected populations in interconnected microcosms. Infection reduced the proportion of hosts dispersing, with levels differing among host clones. Host populations with higher densities showed lower dispersal, possibly owing to social aggregation behaviour. Parasite isolates that depleted host populations most had the lowest impact on host dispersal. Parasite-induced modification of dispersal may have consequences for the spatial distribution of disease, host and parasite genetic population structure, and coevolution.

scholarly journals Tracing the Spatial Distribution of Whole-Lake Exchange of Groundwater and Lake Water in Low-Hydraulic Gradient Systems Using δ18O and Electrical Conductivity and Uncertain End-Member Mixing Analysis

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1608
Author(s):  
Peter Engesgaard ◽  
Ingeborg S. Solvang ◽  
Mads Steiness ◽  
Emil Kristensen ◽  
Theis Kragh ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Spatial Distribution ◽  
Lake Water ◽  
Quantitative Estimation ◽  
Shallow Groundwater ◽  
Direct Analysis ◽  
Hydraulic Gradient ◽  
High Precipitation ◽  
End Members ◽  
Lake Systems

δ18O and electrical conductivity (EC) were used successfully to trace the spatial distribution of whole-lake groundwater-lake exchange for a small (four ha) groundwater-fed lake situated in a low relief and low hydraulic gradient area. The method relies on quick sampling of shallow groundwater, direct analysis of EC in the field, and relatively in-expensive analysis of δ18O in the laboratory. Ternary uncertain end-member mixing analysis (precipitation, groundwater, and lake water) quantified the composition of water discharging to and recharging from the lake. The tracer distribution and mixing analysis were in agreement with the interpreted groundwater flow near the lake. The use of only one tracer (either δ18O or EC) gave the same results for the recharge segments, but the discharge segments changed the origin of the water from being groundwater to precipitation controlled. The two tracers complemented each other, especially with different signals in precipitation and groundwater. The uncertain end-members were assessed based on local (groundwater and lake water) and off-site (precipitation) data. The off-site data were found to be useful if it contained representative information on local-site seasonality (uncertainty, variance). Final end-member concentrations could explain the transience of the hydrology at the site (i.e., flooding of the area adjacent to the lake during periods with high precipitation, and variability of the δ18O signal in precipitation). This methodology potentially represents a new option to study groundwater-lake systems. The tracer information collected over only two days is useful by itself for developing the next steps like the quantification of fluxes based on other standard methods (Darcy approach, seepage meters, or temperature). The tracer information can provide quantitative estimation of inputs and outputs by using the mixing analysis.

scholarly journals Interferometric Observations for O-Containing Organic Molecules Towards Orion-KL

1994 ◽  
Vol 140 ◽  
pp. 238-240
Author(s):  
Y. C. Minh ◽  
M. Ohishi ◽  
D. G. Roh ◽  
M. Ishiguro
Keyword(s):  
Spatial Distribution ◽  
Spatial Resolution ◽  
Organic Molecules ◽  
High Spatial Resolution ◽  
Angular Size ◽  
The Core ◽  
Resolution Observation ◽  
Total Column

AbstractHigh spatial resolution observation (~ 5 arcsec) were made for CH3OH, HCOOCH3, and (CH3)2O toward Orion-KL using the Nobeyama Millimeter Array. The spatial distribution of CH3OH appears to be well elongated along the line connecting IRc2 and “the southern condensation (SC)”. The HCOOCH3 and (CH3)2O emissions appear to be well concentrated to SC with an angular size of ~ 6.5 arcsec. We derive the total column densities 6.8 × 1017cm−2, 1.4 × 1016cm−2 and 2.7 × 1016cm−2 for CH3OH, HCOOCH3, and (CH3)2O, respectively, at the core of SC.

scholarly journals Modelling the tongue-of-ionisation using CTIP with SuperDARN electric potential input: verification by radiotomography

2009 ◽  
Vol 27 (3) ◽  
pp. 1139-1152 ◽  
Author(s):  
S. E. Pryse ◽  
E. L. Whittick ◽  
A. D. Aylward ◽  
H. R. Middleton ◽  
D. S. Brown ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Electric Potential ◽  
Convective Flow ◽  
Ionospheric Plasma ◽  
The Other ◽  
High Latitudes ◽  
Polar Cap ◽  
Radar Network ◽  
Plasma Distribution ◽  
Good Agreement

Abstract. Electric potential patterns obtained by the SuperDARN radar network are used as input to the Coupled Thermosphere-Ionosphere-Plasmasphere model, in an attempt to improve the modelling of the spatial distribution of the ionospheric plasma at high latitudes. Two case studies are considered, one under conditions of stable IMF Bz negative and the other under stable IMF Bz positive. The modelled plasma distributions are compared with sets of well-established tomographic reconstructions, which have been interpreted previously in multi-instrument studies. For IMF Bz negative both the model and observations show a tongue-of-ionisation on the nightside, with good agreement between the electron density and location of the tongue. Under Bz positive, the SuperDARN input allows the model to reproduce a spatial plasma distribution akin to that observed. In this case plasma, unable to penetrate the polar cap boundary into the polar cap, is drawn by the convective flow in a tongue-of-ionisation around the periphery of the polar cap.

Plasma Electric Potential Evolution at the Core and Edge of the TJ-II Stellarator and T-10 Tokamak

2006 ◽  
Author(s):  
L. Krupnik ◽  
A. Melnikov ◽  
C. Hidalgo ◽  
A. Alonso ◽  
A. Chmyga ◽  
...  
Keyword(s):  
Electric Potential ◽  
The Core

scholarly journals Differences in the Climatological Characteristics of Precipitation between Active and Break Spells of the Indian Summer Monsoon

2016 ◽  
Vol 29 (21) ◽  
pp. 7797-7814 ◽  
Author(s):  
T. Narayana Rao ◽  
K. Saikranthi ◽  
B. Radhakrishna ◽  
S. Vijaya Bhaskara Rao
Keyword(s):  
Spatial Distribution ◽  
Indian Summer Monsoon ◽  
Diurnal Cycle ◽  
East Coast ◽  
Large Variability ◽  
Late Night ◽  
The Core ◽  
High Prevalence ◽  
Different Types ◽  
Evening Peak

Abstract Climatological characteristics of precipitation during the active and break spells of the monsoon are studied using 15 years of TRMM measurements. The spatial variation of rain fraction suggests that most of the seasonal rainfall occurs in spells of active monsoon over India, except for the zones along the east coast. The broader reflectivity distribution at higher altitudes and larger average storm height during active spells indicate the high prevalence of deep systems during this spell. The spatial distribution of the occurrence and fraction of different types of rain exhibits large variability from land to ocean and between the spells. The higher occurrence and fraction of stratiform rain during the active spell, particularly over the core monsoon zone, is due to the prevalence of organized mesoscale systems with large stratiform portions. The break spells are characterized by higher occurrence of shallow rain and larger fraction of convective rain. While an evening peak is observed over land during the break spell, the phase of the diurnal cycle exhibits large spatial variability during the active spell. The rainfall peaks from late night to midnight in southeastern India and in the morning near the foothills of the Himalayas during the active spell. The diurnal and semidiurnal components together explain more than 90% of total variance over many of the zones during both spells. The observed differences in precipitation between the spells are discussed in light of the differences in synoptic- and mesoscale mechanisms responsible for the production of precipitation.

Boundaries, Relationality, and Style Provinces in Australian Rock Art

2021 ◽  
Author(s):  
Madeleine Kelly ◽  
Liam M. Brady
Keyword(s):  
Spatial Distribution ◽  
Rock Art ◽  
Formal Analysis ◽  
Social Boundaries ◽  
Northern Australia ◽  
The Core ◽  
Key Indicator ◽  
Art Research ◽  
Similarity And Difference

Identifying style provinces is a popular topic of enquiry in Australian rock art research. At the core of these studies is the focus on the style or manner of depiction of motifs as a key indicator for determining patterns of motif similarity and difference, and their corresponding spatial distribution. In identifying spatial continuities and discontinuities based on a formal analysis of rock art motifs fixed in place, researchers sometimes limit their ability to understand the relational dimensions associated with past and present graphic systems more broadly. This chapter reviews and critiques the formal, style-based methods of delineating discontinuities in rock art as boundaries and uses Nancy Williams’s work on Yolngu boundaries as a framework to further build on research into spatial discontinuities in rock art as flexible, intersecting, and fluid. In doing so, the authors also draw attention to the role of relational understandings and decorative portable objects in characterizing intersecting style-based discontinuities. Using two case studies from northern Australia, they demonstrate how the spatial and social boundaries expressed in rock art are often much more complex than originally envisaged.

Simultaneous detection of lightning flashes by MMIA-ASIM and Colombia Lightning Mapping Array

2020 ◽  
Author(s):  
Jesús Alberto López ◽  
Joan Montanyà ◽  
Oscar van der Velde ◽  
Ferran Fabró ◽  
Javier Navarro ◽  
...  
Keyword(s):  
Multispectral Imaging ◽  
Gamma Ray ◽  
Detection Efficiency ◽  
Simultaneous Detection ◽  
Space Station ◽  
Optical Emission ◽  
High Energy ◽  
Tropical Region ◽  
Mapping Array ◽  
Lightning Leader

<p>Since April 2018, the Atmosphere-Space Interactions Monitor (ASIM) has been in operation on board the International Space Station (ISS). ASIM is composed of the Modular X-and Gamma Ray Sensor (MXGS) as well as a multispectral and high resolution array of photometers and cameras, called the Modular Multispectral Imaging Array (MMIA). These instruments allow us to investigate Terrestrial Gamma-Flashes, Transient Luminous Events and their interactions with thunderstorms and lightning flashes.</p><p>The Colombia Lightning Mapping Array (COL-LMA), operational since 2017, is the first VHF range network installed and working in a tropical region, and can contribute to the electrical understanding of thunderstorms and lightning leader processes associated with high energy phenomena in the upper atmosphere.</p><p>This work employs data from the MMIA array to investigate optical emission patterns at different bands (337 nm, 180-230 nm and 777.4 nm) caused by lightning leader development and cloud-to-ground flashes, derived from the COL-LMA and LINET network respectively. All cases are also correlated with optical observation from the Lightning Imaging Sensor (LIS) on board the ISS, and the Geostationary Lightning Mapper sensor on the GOES-R satellite.</p><p>The region of study is defined by the high detection-efficiency area of the COL-LMA around the Magdalena river valley. MMIA-ASIM information since July 2019 corresponding to passes over this tropical region has been analysed.</p>

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