[Show abstract][Hide abstract] ABSTRACT: The stability of the LIS instrument is examined during a 13 year period (1998-2010) by examining LIS background radiance observations of Deep Convective Clouds (DCCs) which are identified by their cold IR brightness temperature. Pixels in the LIS background image associated with DCCs are identified and analyzed during July and August of each year in the 13 year period. The resulting LIS DCC radiances are found to be stable throughout the period, varying at most by 0.8% from the 13 year mean July August value of 358.1 W sr- 1 m- 2 μm- 1. The DCC method in this study provides a good approach for evaluating the stability of the future GOES-R Geostationary Lightning Mapper (GLM).
[Show abstract][Hide abstract] ABSTRACT: The Geostationary Operational Environmental Satellite R-series (GOES-R) is the next block of four satellites to follow the existing GOES constellation currently operating over the Western Hemisphere. Advanced spacecraft and instrument technology will support expanded detection of environmental phenomena, resulting in more timely and accurate forecasts and warnings. Advancements over current GOES capabilities include a new capability for total lightning detection (cloud and cloud-to-ground flashes) from the Geostationary Lightning Mapper (GLM), and improved cloud and moisture imagery with the 16-channel Advanced Baseline Imager (ABI). The GLM will map total lightning activity continuously day and night with near-uniform storm-scale spatial resolution of 8 km with a product refresh rate of less than 20 s over the Americas and adjacent oceanic regions in the western hemisphere. This will aid in forecasting severe storms and tornado activity, and convective weather impacts on aviation safety and efficiency. In parallel with the instrument development, an Algorithm Working Group (AWG) Lightning Detection Science and Applications Team developed the Level 2 (stroke and flash) algorithms from the Level 1 lightning event (pixel level) data. Proxy data sets used to develop the GLM operational algorithms as well as cal/val performance monitoring tools were derived from the NASA Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) instruments in low Earth orbit, and from ground-based lightning networks and intensive prelaunch field campaigns. The GLM will produce the same or similar lightning flash attributes provided by the LIS and OTD, and thus extend their combined climatology over the western hemisphere into the coming decades. Science and application development along with preoperational product demonstrations and evaluations at NWS forecast offices and NOAA testbeds will prepare the forecasters to use GLM as soon as possible after the planned launch and checkout of GOES-R in late 2015. New applications will use GLM alone, in combination with the ABI, or integrated (fused) with other available tools (weather radar and ground strike networks, nowcasting systems, mesoscale analysis, and numerical weather prediction models) in the hands of the forecaster responsible for issuing more timely and accurate forecasts and warnings.
Atmospheric Research 05/2013; s 125–126:34–49. · 2.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Tropospheric ozone (O3) is a pollutant and major greenhouse gas and its radiative forcing is still uncertain. Inadequate understanding of processes related to O3 production, in particular those natural ones such as lightning, contributes to this uncertainty. Here we demonstrate a new effect of aerosol particles on O3 production by affecting lightning activity and lightning-generated NOx (LNOx). We find that lightning flash rate increases at a remarkable rate of 30 times or more per unit of aerosol optical depth. We provide
observational evidence that indicates the observed increase in lightning activity is caused by the influx of aerosols from a volcano. Satellite data analyses show O3 is increased as a result of aerosol-induced increase in lightning and LNOx, which is supported by model simulations with prescribed lightning change. O3 production increase from this aerosol-lightning-ozone link is concentrated in the upper troposphere, where O3 is most efficient as a greenhouse gas. In the face of anthropogenic aerosol increase our findings suggest that lightning activity, LNOx and O3, especially in the upper troposphere, have all increased substantially since preindustrial time due to the proposed aerosol-lightning-ozone link, which implies a stronger O3 historical radiative forcing. Aerosol forcing therefore has a warming component via its effect on O3 production and this component has mostly been ignored in previous studies of climate forcing related to O3 and aerosols. Sensitivity simulations suggest that 4–8% increase of column tropospheric ozone, mainly in the tropics, is expected if aerosol-lighting-ozone link is parameterized, depending on the background emission scenario. We note, however, substantial uncertainties remain on the exact magnitude of aerosol effect on tropospheric O3 via lightning. The challenges for obtaining a quantitative global estimate of this effect are also discussed. Our results have significant implications for understanding past and projecting future tropospheric O3 forcing as well as wildfire changes and call for integrated investigations of the coupled aerosol-cloud-chemistry system.
Journal of Geophysical Research Atmospheres 10/2012; 117(D18213). · 3.44 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The planned GOES-R Geostationary Lightning Mapper (GLM) will provide
total lightning data to determine the location and intensity of
thunderstorms over the Western Hemisphere. Ongoing GOES-R research
activities using proxy data sets are demonstrating the utility of total
flash rate trends for enhancing forecasting and warning skill for severe
storms. To date, total lightning trends have been well served by
ground-based 3-D VHF systems such as the Northern Alabama Lightning
Mapping Array (NALMA). The NALMA (and other similar networks in
Washington DC and Oklahoma) provide high detection efficiency (> 90%)
and location accuracy (< 1 km) observations of total lightning within
about 100 km from network center. To expand GLM proxy applications for
high impact convective weather (e.g., severe, aviation hazards), it is
desirable to investigate the utility of additional sources of continuous
lightning that can serve as suitable GLM proxy over large spatial scales
(order 100's to 1000 km or more), including typically data-denied
regions such as the oceans. Potential sources of GLM proxy include
ground-based long-range (regional or global) VLF/LF lightning networks
such as the relatively new Vaisala Global Lightning Dataset (GLD360) and
Weatherbug Total Lightning Network (WTLN). Before using these data in
GLM research applications, it is necessary to compare them with LMAs and
other performance-quantified cloud-to-ground (CG) lightning networks,
such as Vaisala's National Lightning Detection Network (NLDN), for
assessment of total and CG lightning location accuracy, detection
efficiency and flash rate trends. Since high impact weather applications
like the Lightning Jump (LJ) algorithm depend on convective cell-based
total flash rates and temporal trends, this study will focus on a
detailed inter-comparison of those lightning network properties on the
spatial and temporal scales of convective cells. Preliminary
inter-comparisons from these lightning networks during selected
convective weather events will be presented and their implications
[Show abstract][Hide abstract] ABSTRACT: In order to produce useful proxy data for the GOES-R Geostationary
Lightning Mapper (GLM) in regions not covered by VLF lightning mapping
systems, we intend to employ data produced by ground-based (regional or
global) VLF/LF lightning detection networks. Before using these data in
GLM Risk Reduction tasks, it is necessary to have a quantitative
understanding of the performance of these networks, in terms of CG
flash/stroke DE, cloud flash/pulse DE, location accuracy, and CLD/CG
classification error. This information is being obtained through
inter-comparison with LMAs and well-quantified VLF/LF lightning
networks. One of our approaches is to compare "bulk" counting statistics
on the spatial scale of convective cells, in order to both quantify
relative performance and observe variations in cell-based temporal
trends provided by each network. In addition, we are using
microsecond-level stroke/pulse time correlation to facilitate detailed
inter-comparisons at a more-fundamental level. The current development
status of our ground-based inter-comparison and evaluation tools will be
presented, and performance metrics will be discussed through a
comparison of Vaisala's Global Lightning Dataset (GLD360) with the NLDN
at locations within and outside the U.S.
[Show abstract][Hide abstract] ABSTRACT: Recent advances in long-range lightning detection technologies have
improved our understanding of thunderstorm evolution in the data sparse
oceanic regions. Although the expansion and improvement of long-range
lightning datasets have increased their applicability, these
applications (e.g., data assimilation, atmospheric chemistry, and
aviation weather hazards) require knowledge of the network detection
capabilities. The present study evaluates data from the World Wide
Lightning Location Network (WWLLN) using observations from the Lightning
Imaging Sensor (LIS) aboard the Tropical Rainfall Measurement Mission
(TRMM) satellite. The study documents the WWLLN detection efficiency and
location accuracy relative to LIS observations, describes the spatial
variability in these performance metrics, and documents the
characteristics of LIS flashes that are detected by WWLLN. Improved
knowledge of the WWLLN detection capabilities will allow researchers,
algorithm developers, and operational users to better prepare for the
spatial and temporal coverage of the upcoming GOES-R Geostationary
Lightning Mapper (GLM).
[Show abstract][Hide abstract] ABSTRACT: The primary science objective for the CHUVA lightning mapping campaign is to combine measurements of total lightning activity, lightning channel mapping, and detailed information on the locations of cloud charge regions of thunderstorms with the planned observations of the CHUVA (Cloud processes of tHe main precipitation systems in Brazil: A contribUtion to cloud resolVing modeling and to the GPM (GlobAl Precipitation Measurement) field campaign. The lightning campaign takes place during the CHUVA intensive observation period October-December 2011 in the vicinity of São Luiz do Paraitinga with Brazilian, US, and European government, university and industry participants. Total lightning measurements that can be provided by ground-based regional 2-D and 3-D total lightning mapping networks coincident with overpasses of the Tropical Rainfall Measuring Mission Lightning Imaging Sensor (LIS) and the SEVIRI (Spinning Enhanced Visible and Infrared Imager) on the Meteosat Second Generation satellite in geostationary earth orbit will be used to generate proxy data sets for the next generation US and European geostationary satellites. Proxy data, which play an important role in the pre-launch mission development and in user readiness preparation, are used to develop and validate algorithms so that they will be ready for operational use quickly following the planned launch of the GOES-R Geostationary Lightning Mapper (GLM) in 2015 and the Meteosat Third Generation Lightning Imager (LI) in 2017. To date there is no well-characterized total lightning data set coincident with the imagers. Therefore, to take the greatest advantage of this opportunity to collect detailed and comprehensive total lightning data sets, test and validate multi-sensor nowcasting applications for the monitoring, tracking, warning, and prediction of severe and high impact weather, and to advance our knowledge of thunderstorm physics, extensive measurements from lightning mapping networks will be collected in conjunction with electric field mills, field change sensors, high speed cameras and other lightning sensors, dual-polarimetric radars, and aircraft in-situ microphysics which will allow for excellent cross-network inter-comparisons, assessments, and physical understanding.
AGU Fall Meeting, San Francisco, December 5 - 9, 2011; 12/2011
[Show abstract][Hide abstract] ABSTRACT: We have been comparing several ground-based lightning RF sensing
networks (LMA, WTLN, WWLLN) with the satellite-based, optical sensing
Lightning Imaging Sensor (LIS). The desire is to create a realistic
proxy dataset for the upcoming Geostationary Lightning Mapper (GLM),
also an optical sensor. The LIS data are the closest approximation that
we have for GLM data, but since it is a Low-Earth Orbiting (LEO) sensor,
any spot on the ground is observed for no more than 80 s. The goal is to
be able to use any ground-based sensing network, which are typically
operated 24x7, and build a transfer function that will allow us to
generate proxy GLM pixels. This process is complicated because ground
networks are RF sensors and the LIS is an optical sensor. This means
that (1) they are sensing different physics during the flash, and (2)
the cloud does not scatter RF, but is a very effective light scatterer.
The North Alabama Lightning Mapper Array (NALMA) is a VHF sensing
network and in a comparison with LIS over many years but limited space
(about 150 km from Huntsville, AL), we find a coincidence rate of
70-80%. The WTLN senses a range of the spectrum from VLF to HF; a
comparison with LIS of a few months of data that ranges across the
Western Hemisphere, we find a coincidence rate of 50-70%. The WWLLN
network senses VLF radiation and a comparison with LIS of one month of
data also covering the Western Hemisphere, we find a coincidence rate of
7-15%. We will show how a transfer function is derived and give details
about how GLM proxy data are generated.
[Show abstract][Hide abstract] ABSTRACT: Lightning activity in thunderstorms are deeply related to the microphysical and kinematic properties of convective clouds, but the relationship between the amount of precipitation and lightning flash rate is not linear and strongly dependent on the local convective regime. As an example, great amounts of precipitation are found over the tropical oceans while lightning is more frequent over the continents, varying from a moderate precipitation-lightning efficiency over the Amazon to regions over the Central Africa with low rainfall but extremely high flash rate activity. These differences are well documented but poorly understood. In this scope, the TRMM satellite has collected for over 12 years detailed measurements of tropical convective cloud systems and their electrification throughout the Precipitation Radar (PR), the TRMM Microwave Imager (TMI) and the Lightning Imaging Sensor (LIS). In particular, the LIS sensor identifies total lightning (intracloud and cloud-to-ground) activity by detecting changes in the brightness of clouds as they are illuminated by lightning electrical discharges. Therefore, LIS operates as a lightning event detector, where several events are grouped in space and time to determine a ``flash''. Flash initiation rate is related to the recharging rate of a local electric field in deep convective cores, while the extent of a flash indicates the extent of charged regions defined primarily by advective processes in the storm updraft. The total flash and group footprint are related to the overall flash extent, and so may indicate important information about ice hydrometeor trajectories into stratiform or anvil regions. We focus our analyses on individual flash and convective areas characteristics from LIS (such as, number of events, groups, total radiance, area footprint, etc.) to identify possible differences in the energetics of the flashes and/or the optical scattering properties of the storms cell due to changes in the microphysics of the clouds (i.e., convective or stratiform rainfall observed from PR and TMI). This type of analyses is important to and can be applied to quantitative precipitation estimation (QPE) using lightning information as constrain for convective and stratiform rainfall partition. Multi-sensor and multi-platform algorithms provide a more complete view of the precipitation processes and aid the procedure of rainfall retrievals.
[Show abstract][Hide abstract] ABSTRACT: RESUMO: Este trabalho apresenta as características e as perspectivas de um "Lightning Mapping Array" a ser implantado na cidade de São Paulo (SPLMA). Esta rede LMA irá fornecer à campanha CHUVA raios totais, mapeamento do canal de raios e informações detalhadas sobre os locais responsáveis pelas regiões de cargas das nuvens de tempestade investigadas durante um de seus períodos de observação intensiva. A disponibilidade em tempo real das observações do LMA também irá contribuir para a concientização da situação meteorológica e apoio à execução da missão do CHUVA. Para o programa do GOES-R irá formar uma base de dados "proxy" única e valiosa para ambos os sensores GLM e ABI em apoio à vários questões de pesquisa em curso. ABSTRACT: This paper presents the characteristics and prospects of a Lightning Mapping Array to be deployed in São Paulo (SPLMA). This LMA network will provide the CHUVA campaign with total lightning, lightning channel mapping and detailed information on the locations of cloud charge regions for the thunderstorms investigated during one of its Intensive Observation Periods (IOP). The real-time availability of LMA observations will also contribute to and support improved weather situational awareness and mission execution. For the GOES-R program it will form the basis of generating unique and valuable proxy data sets for both the GLM and ABI sensors in support of several on-going research investigations.
[Show abstract][Hide abstract] ABSTRACT: While global warming is regarded as a fact by many in the scientific community, its future impact remains a challenge to be determined and measured. The International Panel on Climate Change (IPCC) assessment report (IPCC, 2007) shows inconclusive answers on global rainfall trends and general agreement on a future drier climate with increased global warming. The relationship between temperature, humidity and convection is not linear and is strongly dependent on regional scale features, such as topography and land cover. Furthermore, the relationship between convective lightning production (thunderstorms) and temperature is even more complicated, being subjected to the cloud dynamics and microphysics. Total lightning (intracloud and cloud-to-ground) monitoring is a relatively new field of observation. Global and tropical total lightning began to be more extensively measured by satellites in the mid 90s. In this scope, the Lightning Imaging Sensor (LIS) onboard of the Tropical Rainfall Measurement Mission (TRMM) has been operational for over 11 years. Here we address total lightning trends observed by LIS from 1998 to 2008 in different temporal (annual and seasonal) and spatial (large and regional) scales. The observed 11-year trends are then associate to different predicted/hypothesized climate change scenarios.
[Show abstract][Hide abstract] ABSTRACT: We describe the clustering algorithm used by the Lightning Imaging
Sensor (LIS) and the Optical Transient Detector (OTD) for combining the
space-based observations of lightning pulse data into events, groups,
flashes, and areas. Events are single pixels that exceed the LIS/OTD
background level during a single frame (2 ms). Groups are clusters of
events that occur within the same frame and in adjacent pixels. Flashes
are clusters of groups that occur within 330 ms and either 5.5 km (for
LIS) or 16.5 km (for OTD) of each other. Areas are clusters of flashes
that occur within 16.5 km of each other. The flash data from LIS/OTD are
currently being used for lightning and thunderstorm processes and
climatological studies; therefore we test how variations in the
algorithms for the event-group and group-flash clustering affect the
flash count for a subset of the LIS and OTD data. We divided the subset
into areas with low (1-3), medium (4-15), high (16-63), and very high
(64+) flash counts to see how changes in the clustering parameters
affect the flash rates in these different sizes of areas. We found that
as long as the cluster parameters are within about a factor of two of
the current values, the overall flash counts do not change by more than
about 20%. Therefore the flash clustering algorithm used by the LIS and
OTD sensors are robust and create flash rates that are relatively
insensitive to reasonable variations in the clustering algorithms.
Journal of Geophysical Research Atmospheres 05/2007; 112(D9):9210-. · 3.44 Impact Factor
[Show abstract][Hide abstract] ABSTRACT:  The recently reprocessed (1998–2006) OTD/LIS space-based lightning database is used to investigate the global lightning climatology in response to the ENSO cycle. Temporal correlation maps depicting lightning anomalies- NINO3.4 identify areas that generally follow patterns similar to the widely documented ENSO-related precipitation anomalies. However, areas having statistically significant lightning anomaly-NINO3.4 correlations accompanied by non-significant precipitation anomaly-NINO3.4 correlations are found over the mid-latitudes in both hemispheres. Analysis shows that these areas are related to upper level circulation anomalies (enhanced wind shear) induced by the corresponding ENSO phase. A special case is observed over the western Maritime continent where typical drought conditions during the warm ENSO phase are related to enhanced lightning activity. Further attention is given toward identifying areas over which consistent thunderstorm activity is observed during the two major warm and cold ENSO phases of the past decade. Their spatial distribution shows strong regional preference and in general agrees with the already established ENSO-related precipitation regimes.
Geophysical Research Letters 04/2007; · 3.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: An experimental portable lightning mapping array (LMA) operating in the upper VHF TV band (Channels 7-13; 174-216 MHz) was deployed in the Washington DC Metropolitan area during the summer 2006 to locate and monitor the overall lightning activity. The LMA network provides total lightning data to support lightning research as well as proxy data to benefit the development of applications for planned observing systems such as the GOES-R Geostationary Lightning Mapper. The portable LMA hardware is a compactly-housed, easily deployed version of the LMA stations installed North Alabama, Oklahoma, and New Mexico, which operate in the lower VHF TV band (Channels 2-6, 54-88 MHz). Real-time LMA data products are provided to the National Weather Service Weather Forecast Office (WFO) in Sterling, VA to aid in their forecast and warning operations. Forecasters at WFO Sterling have already found the lightning data from the Washington DC demonstration network to be very useful in assessing the development of storm systems. On July 4, 2006, data from the LMA aided forecasters as they monitored an area of convection that later developed into a line of severe storms that moved southward through the Washington DC metropolitan area across the Washington Mall. Additional applications of lightning mapping data in the Baltimore-Washington DC urban environment will be discussed.
[Show abstract][Hide abstract] ABSTRACT: The goal of this study is to examine cases where there is LIS optical data from above, NLDN and LASA stroke data as well as three dimensional LMA data for the in-cloud processes at a single location. The vicinity of the NSSL in Oklahoma was selected because these four sensor systems routinely gather data there. Between the months of May and December 2005, there were 55 LIS overpasses with lightning data. At the most basic level, the capabilities of each system to detect and locate lightning are compared. Data extractions are performed on the the four continuous data sets to create 55 overpass data sets for lightning within one degree of the Oklahoma LMA. Five overpasses with ground tracks passing very close to the LMA were selected for detailed analysis. Several mechanisms produce some deviation of optical locations from LMA source locations, including optical scattering out of the nearest cloud boundary and residual parallax errors. A detailed examination of data near the ground track provide evidence of a small discrepancy in location that is dependant on satellite attitude.
[Show abstract][Hide abstract] ABSTRACT: The extended lifetime of LIS on the TRMM Mission and the recent installation of the EDOTX sensor system in the Great Plains of the USA provide an opportunity to compare these sets of storm detection and flash location data. The LIS records optical signals emerging through the top of a thunderstorm, while the EDOTX network senses electric field changes from a variety of processes internal to a thunderstorm. On the occasions when the National Lightning Detection Network also identifies a lightning stroke coincident with the other two sensors, error triangles are plotted to illustrate these three determinations of the location of a single event. Subsets are extracted to compare only those lightning events that are within the instantaneous field of view of LIS. Because each system senses a different aspect of a lightning flash, each system can be used to locate the position of an active storm even though they often do not record the same flash. The cases when one system does not detect the same storm as the others will also be examined.
[Show abstract][Hide abstract] ABSTRACT: The North Alabama Lightning Mapping Array became operational in November 2001 as a principal component of a severe weather test bed to infuse new science and technology into the short-term forecasting of severe and hazardous weather, principally within nearby National Weather Service forecast offices. Since the installation of the LMA, it has measured the total lightning activity of a large number of severe weather events, including three supercell tornado outbreaks, two supercell hailstorm events, and numerous microburst-producing storms and ordinary non-severe thunderstorms. The key components of evolving storm morphology examined are the time rate-of-change (temporal trending) of storm convective and precipitation characteristics that can be diagnosed in real-time using NEXRAD WSR-88D Doppler radar (echo growth and decay, precipitation structures and velocity features, outflow boundaries), LMA (total lightning flash rate and its trend) and National Lightning Detection Network (cloud-to-ground lightning, its polarity and trends).For example, in a transitional season supercell tornado outbreak, peak total flash rates for typical supercells in Tennessee reached 70–100 min−1 and increases in the total flash rate occurred during storm intensification as much as 20–25 min prior to at least some of the tornadoes. The most intense total flash rate measured during this outbreak (over 800 flashes min−1) occurred in a storm in Alabama. In the case of a severe summertime pulse thunderstorm in North Alabama, the peak total flash rate reached 300 min−1, with a strong increase in total lightning evident some 9 min before damaging winds were observed at the surface. In this paper, we provide a sampling of LMA observations and products during severe weather events to illustrate the capability of the system, and discuss the prospects for improving the short-term forecasting of convective weather using total lightning data.
Atmospheric Research 01/2005; · 2.20 Impact Factor