ICAE Fall 2000 News Letter
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LABORATOIRE DAEROLOGIE, UNIVERSITE PAUL SABATIER (Toulouse,
The analysis of the data collected during the MAP (Mesoscale
Alpine Programme) field experiment continues by Serge Soula (sous @
aero.obs-mip.fr), Sylvain Coquillat (coqs @ aero.obs-mip.fr), Serge
Chauzy (chas @ aero.obs-mip.fr), and Jean-François Georgis
(geof @ aero.obs-mip.fr). It gives rise to characterize the
precipitation current produced by convective rains. One case of deeply
convective thundercell and several cases of weakly convective events have been
documented. These analyses concern the local measurements on two close surface
sites of the electric field, of the precipitation current density, of the
individual raindrop charges and of the rain microphysics. The dynamical
characteristics of the thunderclouds are obtained from the observations of a
triple Doppler radar system. The scientific questions approached here are (i)
the interpretation of the mirror image effect connecting electric field and
precipitation current, (ii) the characteristics and the origin of the charge
carried down by the precipitation, and (iii) the role of the vertical
development and dynamics of the cloud in the electrification processes. Two
articles are in preparation on this subject.
Based on other data collected during MAP, a study is also
conducted in order to better understand the relation between lightning activity
and thundercloud characteristics. Yann Seity (an engineer from
Météo-France) starts his thesis work on this topic, in
cooperation with Serge Soula and the radar group of the Laboratoire
dAérologie, Frank Roux (email@example.com) and
Jean-François Georgis. The questions approached in this study will
specially be the characterization of the events producing large amounts of
positive cloud-to-ground flashes. As a matter of fact, during MAP experiment,
such cases of storms occurred within the area covered by the radar
A station for continuously measuring the electric field, the
precipitation current density, and the rain microphysics is installed at the
site of the laboratory Centre de Recherches Atmosphériques of
Campistrous (Hautes-Pyrénées) since August 2000, by Serge Soula
and Yves Meyerfeld (firstname.lastname@example.org). These data are collected in order to
systematically study the characteristics of the precipitation current under
various meteorological and seasonal conditions. They will be associated with
radar observations from the operational network of Météo-France.
Sylvain Coquillat, Serge Chauzy, and Fabrice Gangneron
(email@example.com) are developing a new balloon-borne system for in situ
measurements in thunderclouds. This system gathers a radiosonde that provides
thermodynamical characteristics and gives the position of the balloon via a
GPS, a field mill that measures the three components of the electric field, and
a new microphysics sensor. Equipped with a video camera and an induction ring,
this sensor is designed to detect the nature, the shape, the size, and the
electric charge of precipitating hydrometeors. The minimum detected charge will
be ± 2 pC and the maximum about
± 400 pC. A particular care is devoted to the
teletransmission of the data to the ground. The different signals will be sent
separately and the bandwidth of the video signal will be reduced by filtering
to ensure a good transmission without spoiling the hydrometeor pictures. This
system is planned to be used in a forthcoming campaign in Lannemezan at the
Pyrénées foothills, France. For this, radar coverage provided by
Henri Sauvageot (firstname.lastname@example.org), from the radar
group of the Laboratoire dAérologie, will be available. It
involves a polarimetric and a double wavelength radars.
THE UNIVERSITY OF ARIZONA (Tucson, Arizona, USA)
Natalie Murray has recently begun a new study of the space charge
produced by splashing in the surf zone at the NASA Kennedy Space Center (KSC).
Scott Handel has found that the surface electric field just before and during
the onset of isolated storms at KSC is dominated by the appearance of a lower
positive charge center (LPCC) at measuring sites that are close to or directly
under the storm, before the negative charge at higher altitudes dominates the
pattern. Bruce Gungle has examined relationships between cloud-to-ground (CG)
lightning and surface rainfall (measured with gages) in 9 storms at KSC and has
found that there are about 1.5 x 10**4 cubic meters of convective rainfall per
CG flash in both small and large storms. By analyzing the development of 386 CG
flashes recorded on video tape, William Valine has determined that Arizona
storms produce an average of 1.45 strike points per CG flash. W. J. Koshak and
E. P. Krider are continuing to study the response of the NASA Lightning Imaging
Sensor (LIS) when lightning occurs over or near the KSC and are within the LIS
field of view. An effort is also being made to determine if the total light
output from IC or CG discharges, as measured by LIS, is proportional to the
total charge in the flash or any other electrical parameter. As part of the
Thunderstorm Observation and Research (ThOR) initiative at the NASA-GHCC and
the UAH, C. D. Weidman is developing methods for validating the performance of
satellite lightning sensors that can be implemented by elementary, high school,
and college students.
CENTRE FOR EARTH SCIENCE STUDIES (Thiruvananthapuram, India)
Address: PB No. 7250, Thuruvikkal PO, Thiruvananthapuram
Atmospheric electricity was one of the thrust areas identified for
research in the Atmospheric Sciences Division in 1978 when our institution was
started. Initially, we decided to generate data for our region, which was very
meagre. We concentrated on making measurements of ion concentration, ion
mobility and electrical polar conductivities. Quite a bit of time was spent on
the development of the instrument, the Gerdien condenser, for rocket and
balloon-borne measurements. We participated in the Indian Middle Atmosphere
Programme and carried out four measurements in the region from 60 to 90 km
using rockets and four measurements in the region from surface to 33 km using
high altitude balloons. Of the latter, two used self-aspirated instruments and
two force-aspirated ones. Subsequently we were involved in a study of the
influence of the rich deposits of monazite in the coastal sands of our state on
the electrical structure of the atmosphere above the region. This involved
continuous measurement of polar conductivities at the surface at three sites
and surveys using airborne and jeep-borne instruments. The conductivity data
from surface monitoring showed that the diurnal pattern at the radioactive site
changed from one season to another, which is rather unusual. The data also
prompted us to take a look at the causes behind the diurnal variation. It is
this aspect that we are looking at now, through a new project. Our aerial
surveys showed that they could detect the presence of deposits of radioactive
minerals in the soil, providing a simple technique for the purpose. Our work so
far has thus been confined to fair weather studies.
Our present work is in two areas. One is the study of the causes
for the diurnal variation of electrical conductivity. This involves setting up
Gerdien condensers for monitoring positive and negative polar conductivities, a
radioactive potential equaliser probe for monitoring the vertical electric
field, and a weather station for monitoring temperature, humidity, pressure,
wind and rainfall. In addition, the Space Physics Division of the Vikram
Sarabhai Space Centre here will collaborate with us to provide aerosol data.
The weather station has been set up and the fabrication of the Gerdien
condenser is nearing completion. We hope to complete setting up the entire
system within a month or so.
We have taken up studies related to lightning accidents in the
state. As a pilot study, an area that is reported to have had a high incidence
was selected. Data regarding lightning accidents were collected from the local
people, official records and the press. This data were used to determine the
number of lightning incidences in different panchayats (a small administrative
entity). We also conducted awareness camps for the public in two of the
panchayats which had more incidences compared to other nearby areas. A pamphlet
prepared in local language on how to protect oneself during lightning activity
was also distributed during the camps. The reasons for high incidence in a
given area are being now studied from the point of view of terrain and other
geophysical factors. A related study is the mapping of lightning hazard in the
state. The aim of this study is to collect data on lightning strikes from
different sources, including the press, local people and official revenue
records, and prepare a lightning activity map of the state.
Murali Das, S., V. Sasi Kumar and S. Sampath: Measurements of
electrical conductivities, ion densities and mobilities in the middle
atmosphere over India, Indian J Radio Space Phys, 16, 215-220, 1987.
Sampath, S., S. Murali Das and V. Sasi Kumar: Electrical
conductivities, ion densities and mobilities in the middle atmosphere over
India - balloon measurements, J Atmos Terr Phys, 51, 533-540, 1989.
Murali Das, S., S. Sampath and V. Sasi Kumar: Effect of
surface radioactivity on the vertical distribution of atmospheric electrical
conductivities, Indian J Radio Space Phys, 20, 444-445, 1991.
Sampath, S., V. Sasi Kumar and S. Murali Das: Positive and
negative ion densities and mobilities in the middle atmosphere over India -
rocket measurements, J Atmos Terr Phys, 54, 347-354, 1991.
Sampath, S. and V. Sasi Kumar: Electricity in the atmosphere,
Phys Education, 8, 135-147, 1991.
Sasi Kumar, V., S. Murali Das and S. Sampath: Atmospheric
electrical conductivities over a region of high radioactivity, Indian J Radio
Space Phys, 23, 253-258, 1994.
Murali Das, S., V. Sasi Kumar, S. Sampath, T.K.
Krishnachandran Nair, and M. Ismail: Aerial survey of atmospheric electrical
conductivity over a radioactive region using a Pushpak aircraft, Indian J Radio
Space Phys, 23, 380-386, 1994.
Sampath, S., V. Sasi Kumar, and S. Murali Das: Airborne
measurements of atmospheric electrical conductivities, Pure Appl. Geophys.,
143, 713-727, 1994.
Sasi Kumar, V., S. Sampath, S. Murali Das and K. Vijaya Kumar:
Atmospheric electrical conductivity variations over different environments,
Geophys J. Int., 122, 89-96, 1995.
COLORADO STATE UNIVERSITY (Fort Collins, Colorado, USA)
- RADAR METEOROLOGY GROUP
Contribution to STEPS
The Severe Thunderstorm, Electrification and Precipitation
Study (STEPS) field project was conducted from 22 May through 15 July 2000 in
eastern Colorado and western Kansas along the climatological position of the
dry line. The broad goal of STEPS was to achieve a better understanding of the
interactions between kinematics, precipitation production, and electrification
in severe thunderstorms on the High Plains. Several fundamental processes are
still not well understood, but can now be investigated due to technological
advances in instrumentation. STEPS focused on supercell thunderstorms,
including addressing why some supercells produce markedly little precipitation
(LP supercells) while others produce large amounts of precipitation (HP
supercells). STEPS was also interested in examining the lightning behavior
across this spectrum of storms, and sought answers to why some severe storms
produce anomalously large amounts of positive cloud-to-ground lightning. STEPS
deployed the following observing systems to perform coordinated measurements of
environmental wind and thermodynamic vertical profiles, storm windfields,
hydrometeor contents, electric fields, particle charge and lightning. The
deployment of this particular suite of instruments was unprecedented.
- Two S-band polarimetric radars, CHILL from Colorado State
University (CHILL also served as the Operations Center for the field campaign)
and S-Pol from the National Center for Atmospheric Research,
- The South Dakota School of Mines and Technology armored
- A 10 station lightning mapping system from the New Mexico
Institute of Mining and Technology,
- Two mobile environmental sounding systems (MGLASS) from
- Two mobile sounding systems from NOAA/NSSL to collect
balloon-borne measurements of electric fields,
- Six mobile mesonet stations from OU and NSSL to observe the
meteorological conditions and precipitation types beneath storms,
- The Yucca Ridge Field Station (YRFS) for monitoring sprite
activity above the storms sampled in the STEPS domain,
The STEPS observational platforms were deployed in the context
of the National Lightning Detection Network, which provided data on CG
lightning locations, polarity and peak currents, and the NWS NEXRAD network
which provided larger scale context for the research radars. Additionally, the
CHILL, S-Pol and Goodland KS NEXRAD radars formed a triple-Doppler network.
STEPS worked closely on a daily basis with the Goodland KS NWS Weather Forecast
Office. Three NWS personnel produced detailed forecasts for STEPS and worked
closely with STEPS personnel in all aspects of the project. Their insights
regarding the local climatology were particularly helpful to the project. In
this paper we will present the network design and discuss preliminary results
from multiple platform observations of selected case studies. One particular
interesting aspect of the observations suggested that a good number of the
cases sampled, whether severe or not, contained inverted charge structures with
positive charge situated below negative charge. Many storms sampled produced
large fractions of positive cloud-to-ground lightning, including the tornadic
supercell sampled on the evening of 29 June 2000.
structures of tropical precipitation
In a recent paper submitted to J. Climate, Walt Petersen and
Steven Rutledge have combined TRMM Precipitation Radar (PR) and Lightning
Imaging Sensor (LIS) data to examine "wet-season" vertical structures of
tropical precipitation, including ice water content, across a broad spectrum of
locations in the global tropics.
Analysis of reflectivity vertical structure histograms, and
lightning flash density data reveal that: 1) relative to tropical continental
locations, wet-season isolated tropical oceanic locations exhibit relatively
little spatial (and in some instances seasonal) variability in vertical
convective structure across the global tropics; 2) coastal locations and areas
located within 500-1000 km of a continent exhibit considerable seasonal and
spatial variability in mean vertical structure, often resembling "continental"
profiles or falling intermediate to that of tropical continental and isolated
oceanic regimes; and 3)interior tropical continental locations exhibit marked
variability in vertical structure both spatially and seasonally, exhibiting a
continuum of characteristics ranging from a near isolated oceanic profile
observed over the central Amazon and India, to a more robust continental
profile observed over regions of high lightning flash density such as the Congo
and Florida. Examination of regional and seasonal mean conditional instability
for a small, but representative subset of the geographic locations suggests
that tropospheric thermodynamic structure (as opposed to aerosol loading)
likely plays a significant role in the regional characteristics of
precipitation vertical structure and associated lightning flash density. In
general, the largest systematic variability in precipitation vertical structure
observed between all of the locations examined occurred above the freezing
level. Importantly, sub-freezing temperature variability in the vertical
reflectivity structures was well reflected in the seasonal mean lightning flash
densities and ice water contents diagnosed for each location. In turn,
systematically larger rainfall rates were observed on a pixel-by-pixel basis in
locations with larger precipitation ice water content and lightning flash
density. These results delineate, in a regional sense, the relative importance
of mixed phase precipitation production across the global tropics.
Positive cloud-to-ground lightning
In collaboration with Walter A. Petersen and Steven A.
Rutledge, Lawrence D. Carey will present a poster analyzing the positive cloud
-to-ground lightning associated with the Spencer F4 Tornado at the upcoming
Fall 2000 AGU meeting.
On 30 May 1998, a supercell storm spawned five tornadoes, one
of which was rated F4 on the Fujita Damage Scale. The tornadic storm devastated
Spencer, South Dakota, killing 6 people, injuring more than 150 persons, and
destroying nearly 90% of the structures in the community. This supercell
produced over 65% positive cloud-to-ground (CG) lightning and a peak positive
CG flash rate in excess of 16 min-1 (5-minute average). Earlier
studies have reported anomalous positive CG lightning activity in some
supercell storms producing violent tornadoes.
What makes the CG lightning activity in this tornadic storm
unique is the timing of the positive groundstrokes relative to the F4 tornado.
In previous studies, a supercell dominated by positive CG lightning produced
its most violent tornado after it attains its maximum positive ground flash
rate, whenever the rate is in excess of 1.5 min-1. Often, tornado
genesis occurs during a lull in CG lightning activity and sometimes during a
reversal from positive to negative polarity CG lightning. Contrary to these
findings, the positive CG lightning flash rate and percentage of positive CG
lightning in the Spencer supercell began to increase dramatically during
genesis of the tornado and continued to rise while the storm was wreaking
F4 damage on Spencer. The positive CG flash rate finally peaked above 16
min-1 as the tornado exited Spencer and began to weaken, producing
F1 F2 damage.
These results have very important implications for the use of
CG lightning in the Nowcasting of tornadoes and for the understanding of cloud
electrification in these unusual storms.
- COOPERATIVE INSTITUTE FOR RESEARCH IN THE ATMOSPHERE
The U.S. National Weather Service (NWS) is offering
forecasters training on lightning developed at the Virtual Institute for
Satellite Integration Training (VISIT). VISIT member Bard Zajac is the producer
and instructor of lightning training. To date, one training session has been
offered entitled "CONUS CG Lightning Activity." The session covers the
operation and performance of the National Lightning Detection Network and the
climatology of cloud-to-ground lightning (CG) over the contiguous U.S. (CONUS).
This session has been delivered to over half of the 114 NWS local offices using
an distance learning application called VISITview.
The second lightning session entitled "Lightning Meteorology"
will be released before the end of the year. The session will cover
thunderstorm electrification and lightning-thunderstorm behavior using a number
of case studies from AWIPS, the NWS's new platform for viewing weather data and
products. The session emphasizes forecast applications including 1) the
environmental factors and storm characteristics necessary to produce lightning
and 2) lightning activity (-CGs and +CGs) as indicators of storm lifecycle
stage and convective and stratiform rainfall location and intensity. A
follow-up session is planned and will focus on relationships between lightning
and severe weather.
More information on VISIT, VISITview, and lightning training
can be found at: www.cira.colostate.edu/visit.
The point-of-contact for VISIT lightning training is Bard Zajac at:
Contribution to STEPS
CIRA supported STEPS (Severe Thunderstorm, Electrification and
Precipitation Study) by providing real-time satellite loops from RAMSDIS
On-Line, including imagery from GOES Rapid Scan Operations. In addition,
digital McIDAS satellite data was archived from six days. These data can be
used for research and training purposes.
The STEPS home page is located at:
RAMSDIS On-Line is located at:
Bard Zajac is the point-of-contact for the satellite data just described.
COMMUNICATION AND SPACE SCIENCE LABORATORY, PENN STATE UNIVERSITY
(University Park, Pennsylvania, USA)
Les Hale (LesW3LH@aol.com) reports:
In retirement I have been reviewing over 50 years of lightning and
other electromagnetic observations, data, and theory. In the 50's the AE
community and myself tended to believe electromagnetic transients were mainly
of the "relaxation time" variety. ater, people realized this was not always the
case, and that complete solutions of Maxwell's equations, including a
time-varying magnetic field, were necessary to explain the atmospheric data.
This eventually led to things like "FDTD" computer codes, which will not yield
any transient solution without a time varying magnetic field.
It now appears that this viewpoint is also not always correct, as
measurements in the conducting boundary regions show that simple polarization
of the earth and ionosphere boundaries, both by electrostatic fields and
travelling "TEM" waves, and both with large electric fields perpendicular to
the boundaries, penetrate the boundaries much more deeply than "skin depth"
concepts would allow. A frequently valid approximation is in fact the one
dimensional "relaxation time" solution, which far from facilitating
"shielding," simply transmits the field more deeply into the conducting medium,
without attenuation. This solution cannot be generated by "FDTD" codes, which
generally yield answers that are incorrect by many orders of magnitude,
although their proprietors seem to be blissfully ignorant of this.
In the case of the ionospheric boundary, the problem is actually
simplified by the earth's magnetic field, which one-dimensionalizes the field
and results in the polarization of the magnetosphere, with charge deposited at
the base of the magnetically conjugate ionosphere, mainly by the travelling ELF
"slow tails" associated with lightning. This can explain the large mesospheric
electric fields observed by Russian and US groups, and their differences, which
can be explained by the "tilt" of the magnetic field with respect to the axis
of rotation. (Paper presented by L. C. Hale at COSPAR in Warsaw, July, 2000,
submitted to Adv. In Space Res.) A definitive experiment remains to be done
involving simultaneous measurements in magnetically conjugate regions, such as
S. Africa and Central Europe.
This "polarization" concept can also explain the strong
underground current transients measured by our Penn State group and others,
much greater than allowed by "skin depth" concepts or "FDTD" computer models.
It may also explain the large number of unexpected "blasting accidents" during
the construction of new tunnels through the Alps after WW2 reported by Prof. K.
Berger (in Golde's "Lightning," vol.2). The current poor understanding of such
phenomena, institutionalized in "FDTD" computer codes, may constitute a serious
hazard to public safety in the area of mine and pipeline explosions,
LABORATORY OF CONVECTIVE STORM AND LIGHTNING PHYSICS, COLD AND
ARID REGIONS ENVIRONMENTAL AND ENGINEERING RESEARCH INSTITUTE, CHINESE ACADEMY
OF SCIENCES (LANZHOU, CHINA)
(former filiation: Lanzhou Institute of Plateau Atmospheric
Physics, Chinese Academy of Sciences) (From Xiushu QIE - qiex @
Altitude triggered-lightning experiments by using an underground
rocket-launching facility technique were continuously conducted in Summer 2000
at Guangzhou area, southeastern China (email@example.com). The experiments
included (1) continued studies of the interaction of lightning discharges with
ground-based objectives, including lightning rod and Semi-conductor Lightning
Eliminator, in collaboration with Chinese Electrical Power Company. (2)
continued studies of the initiation and propagation of bi-directional leader
system by using high speed video camera, current measurement and two-station
measurements of electric and magnetic fields. This experiment started in summer
1998, and the total number of flashes triggered in the last three years was 12.
The data are being analyzed.
The development of positive leader of an artificially triggered
lightning has been analyzed based on the data of electric field change,
location of radiation source and frequency spectrum obtained by a broadband
interferometer system. The results indicate that radiation from positive leader
could be detected within close distance. Positive leader developed with few
branches, and the initial progression velocity was of the order of
105m/s. A paper titled "Broadband Interferometer Observations of A
Triggered Lightning" by DONG Wansheng (firstname.lastname@example.org), LIU Xinsheng, YU Ye
and Zhang Yijun (email@example.com). has been accepted by the Chinese
The unusual charge structure of thunderstorms in Chinese inland
plateau, located in the verge of Qinghai-Tibetan Plateau, has been continuously
studied by using the data achieved in the last few years. One paper titled
"K-type Breakdown Process of Intracloud Discharge in Chinese Inland Plateau" by
QIE Xiushu (firstname.lastname@example.org), YU Ye, LIU Xinsheng et al. has been published
in the Journal of Progress in Natural Science, 2000, Vol.10, No.8, 607-611.
Another paper titled "Charge Analysis on Lightning Discharges to the Ground in
Chinese Inland Plateau(Verge of Tibet)" by Xiushu QIE, Yu YU, Xinsheng LIU et
al. has been accepted by Annales Geophysicae. It has been verified that a great
positive charge region is widely distributed at the base of the thundercloud.
The analysis also found that the intracloud discharges and positive discharges
usually relate to this charge region. As to why such a large amount of positive
charges exists at the base of the cloud and why lower positive charges seems to
be more effective in discharge processes in Chinese Inland Plateau remain
unanswered. To answer these questions, we plan to organize a big experiment
program during 2001-2003 under the support of NSFC and Chinese Academy of
The interaction between microphysics dynamics and thunderstorm
electrification is continuously studied within the group. Correlation studies
between lightning and precipitation activities have been studied by using the
data of weather radar, meteorological sounding and lightning location system.
We find the regression equation between the rainfall rate (R) and the CG
lightning flash rate (F) is R=1.692lnF 0.273, and the correlation coefficient r
is 0.8641. A paper titled "A Study of the Relationship between Cloud-to-ground
Lightning and Precipitation in the Convective Weather System in China" by
Yunjun Zhou (Zhouyj@ns.lzb.ac.cn), Xiushu Qie and Serge Soula
(email@example.com) has been submitted to Annales Geophysicae.
UNIVERSITY OF FLORIDA (Gainesville, Florida, USA)
A total of 29 lightning flashes were initiated from June 12 to
September 6, 2000 at the International Center for Lightning Research and
Testing (ICLRT) at Camp Blanding, Florida. Of these 29, 26 contained downward
leader/upward return stroke sequences, and 3 were composed of the initial stage
only. All triggered flashes effectively transported negative charge to
Seventeen flashes were triggered from an underground
rocket-launching facility surrounded by a 70 x 70 m2 buried metallic
grid. Direct return stroke current derivative measurements and associated
electric and magnetic field derivative measurements at 15 and 30 m were
obtained. Further, electric fields at three distances (5, 15, and 30 m) and
magnetic fields at two distances (15 and 30 m) for lightning M components were
simultaneously measured. Electric fields were also recorded using Pockels
sensors installed at a radial distance of 10 cm and at a height of 10 cm from
the tip of the lightning strike rod, the closest lightning electric field
measurements ever obtained. The position of the lightning channel with respect
to the sensor varied for different events from 10 cm or less (in one case the
channel was in contact with the sensor) to a few meters. This latter experiment
was performed in collaboration with Megumu Miki of CRIEPI, Japan. Acoustic
shock waves were recorded at about 2, 15, and 30 m from the lightning channel.
It appears that all impulsive processes in the lightning discharge, including
M-component type processes, produce acoustic shock waves. Triggered-lightning
return stroke shock waves resemble those produced by the 4-m laboratory sparks
studied by Uman et al. (1970). Preliminary results of the experiments conducted
using the underground rocket launcher will be presented at the Fall 2000 AGU
Twelve flashes were triggered using the tower rocket launcher.
Lightning current was directed to a phase conductor (at mid-span or at a pole)
near the center of a three-phase test distribution line. The line had a length
of 829 m and was protected by six lightning arresters. The results of this
experiment are found in Ph.D. dissertation "Interaction of Lightning with Power
Distribution Lines" by Carlos Mata.
David Crawford, Vladimir Rakov, Martin Uman, George Schnetzer,
Keith Rambo, and Michael Stapleton authored a paper, submitted to the JGR,
titled "The Close Lightning Electromagnetic Environment: Leader Electric Field
Change vs. Distance". Leader electric field changes due to triggered-lightning
strokes from experiments conducted in 1997, 1998, and 1999 at the ICLRT at Camp
Blanding, Florida are analyzed and compared to similar data obtained in 1993 at
Camp Blanding and at Fort McClellan, Alabama. In 1997-1999, the fields were
measured at 2 to 10 stations with distances from the lightning channel ranging
from 10 to 621 m, while in 1993, the fields were measured at three distances
(30, 50 and 110 m) in Florida and at two distances (about 10 and 20 m) in
Alabama. With a few exceptions, the 1997-1999 data indicate that the distance
dependence of the leader field change is close to an inverse proportionality
(r 1), in contrast with the 1993 data in which a somewhat
weaker distance dependence was observed. The observed r 1
dependence is consistent with a more or less uniform distribution of leader
charge along the bottom kilometer or so of the channel.
Rouzbeh Moini, Behzad Kordi, G.Z. Rafi (Amirkabir University of
Technology, Iran), and Vladimir Rakov authored a paper, accepted for
publication in the JGR, titled "A New Lightning Return-Stroke Model Based on
Antenna Theory". A new approach based on antenna theory is presented to
describe the lightning return-stroke process. The lightning channel is
approximated by a straight and vertical monopole antenna with distributed
resistance (a so-called lossy antenna) above a perfectly conducting ground. The
antenna is fed at its lower end by a voltage source such that the antenna input
current, which represents the lightning return-stroke current at the lightning
channel base, can be specified. An electric field integral equation (EFIE) in
the time domain is employed to describe the electromagnetic behavior of this
lossy monopole antenna. The numerical solution of EFIE by the method of moments
(MOM) provides the time-space distribution of the current and line charge
density along the antenna. This new antenna-theory (or electromagnetic) model
with specified current at the channel base requires only two adjustable
parameters: the return-stoke propagation speed for a nonresistive channel and
the channel resistance per unit length, each assumed to be constant
(independent of time and height). The new model is compared to four of the most
commonly used "engineering" return-stroke models in terms of the
temporal-spatial distribution of channel current, the line charge density
distribution, and the predicted electromagnetic fields at different distances.
A reasonably good agreement is found with the modified transmission line model
with linear current decay with height (MTLL) and with the Diendorfer-Uman (DU)
The following three papers were presented by the UF group at the
25th International Conference on Lightning Protection:
- "Lightning Properties from Triggered-Lightning Experiments at
Camp Blanding, Florida (1997-1999)", in Proc. of the 25th Int. Conf.
on Lightning Protection, Rhodes, Greece, September 18-22, 2000, pp. 54-59, V.A.
Rakov, M.A. Uman, D. Wang, K.J. Rambo, D.E. Crawford, and G.H. Schnetzer.
- "Triggered Lightning Testing of an Airport Runway Lighting
System", in Proc. of the 25th Int. Conf. on Lightning Protection,
Rhodes, Greece, September 18-22, 2000, pp. 825-830, M. Bejleri, V.A. Rakov,
M.A. Uman, K.J. Rambo, C.T. Mata, and M.I. Fernandez.
- "Positive and Bipolar Lightning Discharges: A Review", in Proc.
of the 25th Int. Conf. on Lightning Protection, Rhodes, Greece,
September 18-22, 2000, pp. 103-108, V.A. Rakov.
INDIAN INSTITUTE OF TROPICAL METEOROLOGY (IITM) (Pune, India)
The Indian Institute of Tropical Meteorology (IITM) functions as a
national centre for basic and applied research in monsoon meteorology of the
tropics in general with special reference to monsoon meteorology of India and
neighbourhood. Its primary functions are to promote, guide and conduct research
in the field of meteorology in all its aspects. IITM has made significant
contributions in the challenging areas of the Meteorology and Atmospheric
Sciences like Weather Forecasting, Monsoon, Cloud Physics, Weather
Modification, Atmospheric Chemistry, Atmospheric Electricity, Climatology and
Global Change, Hydrometeorology, Monsoon, Climate Modelling.
Studies in Atmospheric Electricity is one of the projects of
Physical Meteorology and Aerology Division of the IITM. Under this project the
continuous observations of different electrical parameters such as electric
field, point discharge current, drop charge etc. were taken since the 1970 at
this station (Pune) and also in different environmental conditions. The present
study deals with the behavior of one of the above mentioned electrical
parameters. Dr. S.S. Kandalgaonkar, Dr. M.I.R. Tinmaker, and Dr. M.K. Kulkarni,
report about their findings on "Time evaluation and frequency distribution
of point discharge current over Pune region": One minute interval data
of Point discharge Current (PDC) collected for a total of 65 thunderstorm days
occurred during 6 years period (1972-1977) at Pune (18°32'N, 73°51'E,
559 m asl) forms the data set for the present study. This data has been
analysed to study its time variation and also analyzed statistically to study
its frequency distribution. For this purpose the total diurnal period (0000 -
2359 IST) is divided into 3 distinct time intervals i.e. afternoon (1400-2100
IST); night time (2100-0759 IST) and day time (0800-1400 IST). The number of
data points for positive and negative polarity in each of the above time
interval were 5649 & 4399; 1289 & 1091 and 479 & 411 respectively.
These data points for each time interval were subjected to their frequency
distribution. For each category, the data has been divided into 24 class
intervals (i.e. 13 for negative polarity and 11 for positive polarity) ranging
from -6.5 to 5.5 µA with uniform class width of 0.5 µA.
The percentage occurrence of PDC of either polarity for total diurnal period
and also for the above 3 categories of time interval for individual class
interval were obtained. The computed values were evaluated by applying Gaussian
Model, which suggests that the distribution is normal and the chi-square value
obtained (5.2008) is less than the standard table value (9.542) for 22 degrees
of freedom. From this it is seen that the hypothesis applied to the above data
holds good. Since it is a normal distribution the data has been further tested
by using Fischer's test for the skewness and kurtosis. The results thus
obtained suggests that the distribution is found to be normal with negative
skewness and exhibits the property of leptokurtic distribution. Temporal
analysis of this data suggests that the behaviour of PDC of either polarity in
the first category of time interval (i.e. 0800-1400 IST) is found to be
identical (contribution of positive and negative PDC is nearly same) with the
overall contribution of PDC during the total diurnal period (0000-2359 IST),
whereas for second and third category the contribution of PDC of either
polarity is observed to be in the opposite sense. This result is curious. The
sustained occurrence of negative and positive PDC at the end of the storm day
in second and third category of time interval may be due to the presence of
excess positive and negative space charges in the corresponding category of
time interval, and their concentrations also increases with increasing
instability (for second category of time interval) and stability (for third
category of time interval) respectively during that time intervals (Law, 1962).
INSTITUTE OF ATMOSPHERIC SCIENCES, SOUTH DAKOTA SCHOOL OF MINES
AND TECHNOLOGY (Rapid City, South Dakota 57701, USA)
At the South Dakota School of Mines and Technology (SDSMT) efforts
continue in the areas of modelling of lightning and electrification in
convective storms, and the analysis of field observations of convective storms.
On the observations side, John Helsdon, Andy Detwiler, Qixu Mo, Donna Kliche,
and Jessica Irvin, are beginning to analyse observations obtained with the
SDSMT armored aircraft during the Severe Thunderstorm Electrification and
Precipitation Study (STEPS) field program during May-July, 2000, in eastern
Colorado/western Kansas. The analysis of airborne observations will be combined
with observations from multiparameter Doppler radars, the NMIMT lightning
mapper array, NSSL/OU electrical soundings, and other STEPS observations for
several very interesting cases of both normal polarity and inverted-polarity
On the modeling side, Helsdon, Dick Farley and Xingjun Zhang
continue their efforts to model the production of NOx compounds by lightning in
convective storms. Helsdon, Farley, and Inna Suz are continuing work on the
simulation of lightning in 3D cloud models, including cloud-to-ground strokes.
Both Mr. Zhang and Ms. Sus expect to finish their graduate work this year.
The SDSMT armored T-28 suffered a major engine failure late in the
STEPS field program. A replacement engine is currently being outfitted and we
expect to have the aircraft flying again by early next year. We are lookingfor
new projects during the next few years in which the aircraft can make a
contribution. As most of you know, the aircraft has base support from the US
National Science Foundation (NSF), and funding for participation in field
projects is also available from the NSF, through a formal request and
panel-review process. If you have a project to which the aircraft can
contribute, please contact Andy Detwiler at firstname.lastname@example.org, or
At this time, the NSF is also evaluating several candidate
aircraft with superior performance characteristics to take over storm
penetration work from the T-28 and provide in situ observations at higher
altitudes and for longer periods than are possible with the T-28. One example
of a viable candidate is the US Air Force A-10 fighter/bomber. If you have
ideas or comments concerning suitable aircraft and/or instrumentation issues,
pleasecontact Jim Huning, Lower Atmospheric Observing Facilities program
manager at the NSF (email@example.com)
MASSACHUSETTS INSTITUTE OF TECHNOLOGY (Lincoln Laboratory,
Lexington, Massachusetts, USA)
Upsurges in total lightning activity 5-20 minutes prior to
tornadoes have now been observed for numerous case studies in Florida with the
operational LISDAD (Lightning Imaging Sensor Data Application Demonstration)
system, in collaboration with Steve Goodman and Dennis Buechler at NASA MSFC.
Traditional Doppler radar observations of tornadogenesis make use of
time-height plots of rotational velocity, vorticity, and the operational
tornado vortex signature (TVS). We are making use of a quasi-conservative
angular momentum density which is the product of local air density, rotational
velocity and the radius of the velocity couplet. In several cases (including
the August 1998 tornado in Salt Lake City), this quantity shows a pronounced
enhancement aloft (3-8km) followed by a substantial decrease aloft at the time
the tornado is reported on the ground. These observations support the
traditional view that the angular momentum in the tornado is drawn from a
reservoir aloft. The apparent descent of angular momentum is consistent with
the notable diminishments in total lightning rate at the time of the
MASSACHUSETTS INSTITUTE OF TECHNOLOGY (Parsons Laboratory,
Cambridge, Massachusetts 02139, USA)
Recent examination of long-term recordings of the Earths
Schumann resonances in Hungary (G. Satori), Antarctica (M. Fullekrug and A.
Fraser-Smith) and Rhode Island (R. Boldi, V. Mushtak and E. Williams) has
revealed a systematic variation in the resonant frequency of the
Earth-ionosphere cavity over the 11-year solar cycle. These frequency
variations are distinguishable from more routine variations associated with
source-receiver distance variability on the basis that all resonant frequencies
at all three sites change in the same sense. The frequency increase toward
solar maximum is interpreted as an increase in the phase velocity of cavity
waves associated with an increased conductivity in the upper dissipation layer
of the D-region, induced by solar x-ray enhancement.
Observations of sprites continue to show a diffuse quasi-uniform
structure at high altitudes and a channeled structure at lower altitudes (and
higher air density). A simple explanation for these observations has been
constructed based solely on geometry and on values of two parameters: the
electron mean free path and the mean distance between free electrons. The
former quantity increases with altitude and the latter quantity decreases with
altitude. Free electrons are nucleation sites for dielectric breakdown. When
breakdown sites are closed spaced relative to the scale of breakdown (the mean
free path), the discharge is guaranteed to be homogeneous. When the breakdown
sites are relatively isolated, one has the possibility for local avalanching to
the streamer state and subsequent propagation by concentration of the electric
field at the periphery of the conductive plasma, resulting in a very
heterogeneous structure. The crossover altitude between mean free path and mean
distance between free electrons is 70-75 km, in reasonable agreement with the
observations on the altitude of structure change. Elves and haloes above this
level are diffuse, whereas sprites tendrils, blue jets and lightning itself at
lower levels of the atmosphere are structured.
UNIVERSITY OF MISSISSIPPI (University, Mississippi, USA)
Tom Marshall, Maribeth Stolzenburg, and physics graduate student
Lee Coleman are continuing analyses of balloon, radar, and lightning data from
two recent field experiments: MEaPRS (MCS Electrification and Polarimetric
Radar Studies, May and June 1998, in the southern Great Plains) and SEET (Study
of Electrical Evolution in Thunderstorms, July and August 1999, at Langmuir Lab
in New Mexico).
One MEaPRS study (with co-authors Dave Rust, Earle Williams, and
Bob Boldi) includes a balloon sounding of electric field through the trailing
stratiform cloud of a bow echo mesoscale convective system. The sounding showed
only two substantial in-cloud positive charge regions, at 5.1-5.6 km and
6.4-6.8 km altitude. Based on Schumann resonance Q-burst data acquired by Earle
Williams and Bob Boldi, the amount of charge transferred by three positive CG
flashes with large peak currents that occurred within 60 km of the balloon
during its flight was in the range of 97-196 C. Another MEaPRS case (with
co-author Dave Rust) includes five partial balloon soundings in an updraft and
outside the updrafts of the convective region, in the transition zone, and in
the stratiform cloud region of an MCS. Both these studies have been submitted
for publication in the Journal of Geophysical Research.
Data from SEET are currently being used for three evolution
studies on (a) early electrification, (b) the end-of-storm oscillation, and (
c) a detailed comparison of charge location inferred from balloon soundings to
lightning paths from New Mexico Techs Lightning Mapping Array. These
analyses are in collaboration with numerous colleagues at New Mexico Tech.
Tom and Maribeth are also collaborating with Eugene Mareev and
Stanislav Davydenko at the Institute of Applied Physics in Nizhny Novogorod on
the contribution of MCSs to the global electric circuit.
NATIONAL LIGHTNING SAFETY INSTITUTE (NLSI), (Louisville,
1. NLSI is serving as a contributing member of the Department of
Defense Explosive Safety Board (DDESB) Lightning Committee. We are re-writing
the military lightning protection guideline, document 6055.9 to conform to
latest information, taking into account NATO and other science-based standards.
In previous renderings 6055.9 emphasized the NFPA 780 approach. Since 780 was
downgraded in 1999, together with the present indecisiveness of that
organization, it is no longer prudent to recommend only the installation of air
terminals as a lightning defense.
2. At this writing, NLSI has graduated about 90 students from the
intensive two day Lightning Safety Workshop during the year so far. Seminars
were conducted in: Washington DC; Los Alamos New Mexico; Cuidad del Carmen,
Mexico; and Louisville Colorado. Graduates of the workshop were employed by
FAA, NASA, EPA, DOE, US Air Force, US Navy, Defense Threat Reduction Agency, US
Coast Guard, electric power utility companies, park and recreation districts
from local governments, insurance companies, explosives manufacturing
companies, amusement parks and lightning protection companies.
- Interesting site review and consulting assignments have
- Explosives chemical manufacturing factory, Arizona. With 1000
employees and buildings over a 1.5 km sq. area, lightning visited three times
over the past 18 months. NLSI recommended upgrades to the lightning detection
system, attention to bonding detail in electrostatic environments; and a
complete characterization of the NFPA 780 lightning protection system to bring
it into compliance.
- Wind turbine farm, New York. This is a new installation. NLSI
recommended compliance with the IEC standards for wind turbines, plus lightning
- Department of Energy storage of low level nuclear waste,
Colorado. NLSI reviewed the exiting LPS and suggested improvements, including
installation of surge protection devices conforming to IEEE Std. 1100.
- Denver International Airport and Dulles International Airport.
We reviewed safety procedures for ramp workers and suggested more conservative
policies based upon improved lightning detection, notification and resumption
of activities. Lightning has injured one worker in Denver and seven workers in
Atlanta at respective airports in 2000.
- Ski area, Utah. Working for an insurance firm which insures 160
USA/Canadian Ski areas, NLSI prepared a comprehensive Lightning Safety Protocol
for the Client. Included here were recommendation for attention to grounding,
bonding, shielding, surge protection to protect electronic equipments. This
Protocol will be a guideline document for winter and summer ski are operations.
Summer operations include considerable tourism, mountain biking, and hiking
activities. (At Vail Ski Area in Colorado a skier was killed by winter
lightning in 1993.)
NATIONAL SEVERE STORMS LABORATORY, NOAA (Norman, Oklahoma,
Dave Rust and Don MacGorman of the National Severe Storms
Laboratory participated with a team of students and colleagues to fly
instrumented balloons into severe storms during the Severe Thunderstorm
Electrification and Precipitation Study (STEPS) during the spring and early
summer in the region of northwest Kansas. Even with a drought in place for much
of the project, several interesting profiles of the electric field were
obtained. These data are being analyzed and combined with radar and lightning
mapping array data. Thirty flights were made, and a few were into the
mesocyclones of tornadic storms. A major goal will be to look at the electric
structure in strong updrafts and to look for charge structures during normal
and inverted-polarity intracloud discharges found to be numerous during
Sites are being selected in central Oklahoma for the installation
of a New Mexico Tech built lightning mapping array. We anticipate this system
being operational for this spring for coordinated data acquisition with it,
instrumented balloons for electric field profiles, and two new mobile C-band
Doppler radars (being built by Texas A&M, Oklahoma University, Texas Tech
University, and the National Severe Storms Laboratory). This will likely be a
small field project, designed as a shake down of these and other new
OFFICE NATIONAL DETUDES ET DE RECHERCHES AEROSPATIALES
Atmospheric Environment Research Group (Paris, France)
Pierre Laroche (firstname.lastname@example.org) www.onera.fr
Anne Bondiou-Clergerie (email@example.com), Alain Delannoy
(firstname.lastname@example.org), Philippe Lalande (email@example.com), and Patrice
Blanchet (firstname.lastname@example.org) proceed with the preparation of a prototype of the
payload of the future ORAGES mission. ORAGES consists in the location of
lightning flashes from a microsatellite, using interferometer in VHF band. A
flight of the prototype on a stratospheric balloon is planned for mid 2001.
Preparation of this project is supported by analyses of data from the Los
Alamos FORTE mission (Abe Jacobson - email@example.com). Serge Chauzy, Serge
Soula and Franck Roux from the Laboratoire dAérologie de Toulouse
contribute to this preparation. ORAGES preliminary studies are funded by CNES,
the French Space Agency.
Total lightning activity data collected in various areas of the
world with Oneras 3D VHF interferometric system are currently used by
Claire Thery (firstname.lastname@example.org) and Eric Defer (email@example.com) at NCAR to
perform analyses of relation between convective activity and lightning
activity. Both Claire and Eric made some comparison between the interferometer
and other mapping systems. Collaboration with Harmut Hoeller
(Hartmut.Hoeller@dlr.de) at DLR carries on to derive a parameterization of
lightning activity within storms.
Anne Bondiou-Clergerie and Philippe Lalande continue their
modelling effort to describe the sweeping of a lightning flash on an aircraft
with the participation of Anders Larson of Lundt University in Sweden. They
achieved a fruitful study of aircraft radom lightning protection based on
modeling and experiment realized with Alain Ulmann at CEAT (Centre
dEssais Aeronautiques de Toulouse) - firstname.lastname@example.org.
POLISH ACADEMY OF SCIENCES (Warsaw, Poland)
The atmospheric electricity research group at the Institute of
The electric charge on the precipitation particles transported to
the earths surface and other electrical parameters (electric field, space
charge density, electric currents) were measured in Warsaw for the cases of
nearby thunderstorms monitored by radar (P. Baranski; email@example.com)
The data from the Siemens Central European Lightning Detection
Network (CELDN) were used for detection and location of cloud-to-ground
discharges in surrounding region of Warsaw. A comparison of those data with the
corresponding electric field recordings in Warsaw station is applied to
eliminate the false identifications of the CELDN network. The corrected CELDN
data overlapped on the thundercloud radar pictures are analyzed to find, if
any, a regularity of appearance of clusters of positive flashes in special area
of the radar echo (P. Baranski).
The study on initiation of lightning discharge is continued
(Nguyen Manh Duc, S. Michnowski;firstname.lastname@example.org).
The atmospheric electricity recordings since 1956 are continued
on the background of meteorological, aerosol, radioactive and chemical
pollution observations at Swider Geophysical Observatory (M. Kubicki;
email@example.com). The results are being published and exchanged (M.
The electric field and vertical air-earth current recordings
accompanied by the meteorological observations and geomagnetic, riometer and
other geophysical measurements are carried on at the polar station at Hornsund,
Spitsbergen (M. Kubicki).
Works on developing new designs of electric field, air-earth and
space charge density sensors are under way (M. Kubicki, J. Drzewiecki, J.
The local effects at Hornsund and Swider on the electric field
and air-earth current variations are studied (M. Kubicki, S. Warzecha).
The effects of interplanetary magnetic field on the electrical
variation at the ground in Hornsund are being examined (S. Michnowski, N.
Kleimenova, S. Israelsson, N. Nikiforova, J. Drzewiecki and M. Kubicki).
TEL AVIV UNIVERSITY, DEPARTMENT OF GEOPHYSICS AND PLANETARY
SCIENCES (Tel Aviv, Israël)
The team led by Prof. Zev Levin, Dr. Colin Price and Dr. Yoav Yair
will try and obtain high-resolution images of sprites from space during the
MEDIEX campaign, and correlate them with ground-based ELF-VLF measurements. The
present launch date for STS-107 (the space shuttle Columbia) is summer 2001,
for a 16 day mission at 39 degrees inclination. The payload consists of a
multi-spectral Xybion IMC201 camera that will be operated by an Israeli
astronaut in cooperation with a ground team located at NASA/GSFC. Images will
be recorded on digital VCRs in the crew-cabin and downlinked to the ground.
Observational runs would consist of continuous recording of the Earths
limb from the direction of the dusk terminator towards the night side,
preferably before midnight local time at the observed area. In order to enhance
the success probability, as many thunderstorms as possible would be targeted.
The observation areas would cover an area that extends from 39S to 39N, along
the shuttle orbit. The most (active) desired areas will be tropical South
America, North-Australia and Indonesia, South-East Asia, China, Sea of Japan,
Continental USA and the Gulf of Mexico. Several groups have expressed interest
in the MEDIEX-Sprite campaign and will collect electromagnetic and optical data
during the mission. These include Earle Williams (MIT), Umran Inan (Stanford),
Walt Lyons (FMA Research Inc.), Marcelo Saba (Brazil), Zen Kawasaki (University
of Osaka, Japan) and Martin Fullekrug (Frankfurt, Germany).
Orit Altaratz, Prof. Zev Levin and Dr. Yoav Yair continue the
study of the properties of winter thunderstorms along the coast of Israel, with
special emphasis on the differences between the areas near Tel-Aviv and Haifa.
The objective is to understand the role of different parameters, such as
topography, sea-land temperature difference and aerosol particles concentration
in affecting the dynamical and microphysical characteristics of thunderclouds
in this region. Part of this study is carried out by analyzing data from
lightning detection systems (LPATS, CGR3 and LIS) and data from the Tel Aviv
University radar. In addition, a numerical study is being carried out by using
the RAMS model to simulate the evolution of clouds, including electrical charge
separation and electric field build-up, as they move from the Mediterranean Sea
toward the coast.
Mustafa Asfur, under the guidance of Dr. Colin Price, completed
his M.Sc. thesis on ELF sprite detection. Analysis of ELF data collected in
Israel during the SPRITES 99 field campaign show that we were able to
temporally and spatially locate the majority of the optically-observed sprites
imaged by Dr. Walt Lyons in Colorado, 11,500 km away. We detected 3 times more
ELF transients originating from the storm of 18 August, 1999, than were
observed visibly by Walt Lyons. Whether all these transients were related to
sprites is presently under investigation.
Moshe Blum and Dr. Colin Price are studying the VLF pulses
produced by meteors entering the atmosphere. We have found a close link between
the frequency of meteors during the Leonid 99 meteor shower and the
frequency of VLF pulses identified with the meteors. We have found a unique
spectrum related to the meteors, very different to the normal lightning
discharge spectrum, hence allowing us to differentiate between the two.
Dr. Colin Price continues his research on Schumann resonances
related to climate change. A recent paper relating global lightning activity to
upper tropospheric water vapor appeared in Nature this summer (Nature, Vol.
406, pp. 290-293). In addition, Colin Price and Sasha Nickolaenko (Ukraine)
have published a paper recently looking at the statistical properties of the
background Schumann resonance signals using the Hurst exponent (GRL, Vol. 27,
TEXAS A&M UNIVERSITY, DEPARTMENT OF ATMOSPHERIC SCIENCES
(College Station, Texas 77843-3150, USA)
- We have completed an initial mapping project to analyze the
flash density, positive flash density, and the percentage of positive lightning
flashes for 115 sites in the continental United States. The 345 maps have a
spatial resolution of 5 km and covers eleven years, 1989-1999. These initial
maps are pointing the direction for some of our future research and represent a
first look at the cloud-to-ground lightning characteristics in the USA with
relatively high spatial resolution. Access to the maps is obtained by going to
and clicking on NOAA/NWS Regional Lightning Maps. When you are asked for a name
and password, use the following:
If there are any problems, you can contact me at
- We have recently published a paper in Geophysical Research
Letters detailing the effects of the smoke intrusion into the USA in the spring
of 1998. The citation is: Murray, N. D., R. E. Orville, and G. R. Huffines,
2000, "Effect of pollution from Central American fires on cloud-to-ground
lightning," Geophys. Res. Lett., 27, (15), August 1, 2000, 2249-2252. The
published version of our paper, in pdf format, is available at the following
- A paper summarizing the first ten years of the NLDN
cloud-to-ground lightning data is now in press for the Monthly Weather Review.
The citation is: Orville, R. E. and G. R. Huffines, 2001, "Cloud-to-ground
lightning in the USA: NLDN results in the first decade 1989-1998," Mon. Wea.
Rev., 129, (In press). Electronic pdf copies of the paper can be obtained by
emailing either one of the authors (firstname.lastname@example.org or Gary1 Huffines
THE UNIVERSITY OF UTAH (Salt Lake City, Utah 84112-0110,
Ed Zipser (email@example.com) moved from Texas
A&M University to the University of Utah in March 1999, but as recently as
the last week in October 2000, his last two students at Texas A&M
successfully defended their dissertations there. Both deal with the question of
land vs. oceanic lightning using LIS, radar, and passive microwave data from
the TRMM (Tropical Rain Measuring Mission) satelllite. Rick Toracinta's work
contrasts properties of precipitation features (PFs) over large areas of the
tropical Pacific Ocean, tropical South America, and tropical Africa. It has
been known for some time that Africa is the champion lightning producer,
followed by South America and with oceanic lightning scarce. Rick carefully
normalizes the PFs by strength of the ice scattering signature at 37 and 85
GHz, and finds that for the same brightness temperature that the probability of
LIS-detected lightning is still an order of magnitude greater over land than
ocean. Even more startling, when normalizing fo! r radar reflectivity at any
level, probability of lightning is still much greater over land. Dan Cecil uses
the same database as a reference, and does the same type of analysis for
tropical cyclones, separating the eyewall, inner rainbands, and outer
rainbands. For a far larger database, he finds that the outer bands are more
likely to have lightning than the other regions of the hurricane, in agreement
with Molinari. When normalized by brightness temperature or radar profiles, the
lightning probabilities are less than over continents but greater than over
oceans outside of hurricanes.
Depending on the outcome of pending proposals, Zipser plans to
continue field studies on tropical convection in the NASA and U.S. Weather
Research Program supported Convection and Moisture Experiment (CAMEX-4) in
August-September 2001. In the meantime, his research group in Utah has ample
data from TRMM and from several of the TRMM validation field programs held in
1998 and 1999.