Some Scientific Objectives of a Satellite-Borne Lightning Mapper (original) (raw)
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Satellite measurements of global lightning
Quarterly Journal of the Royal Meteorological Society, 1998
The satellite-borne NASA/MSFC Optical Transient Detector provides global distributions of lightning and lightning-stroke radiance. Measurements made during the first year of its operation show that lightning activity is particularly pronounced over the tropics, much greater over land than over the oceans, and exhibits great seasonal variability. The values of lightning-stroke radiance tend to be greater over the oceans, less when lightning activity is high, and greater in the northern hemisphere winter than summer.
Global lightning and severe storm monitoring from GPS orbit
2004
Over the last few decades, there has been a growing interest to develop and deploy an automated and continuously operating satellite-based global lightning mapper [e.g. Christian et al., 1989; Weber et al., 1998; Suszcynsky et al., 2000]. Lightning is a direct consequence of the electrification and breakdown processes that take place during the convective stages of thunderstorm development. Satellite-based lightning
A GPS-based three-dimensional lightning mapping system: Initial observations in central New Mexico
Geophysical Research Letters, 1999
A GPS-based system has been developed that accurately locates the sources of VHF radiation from lightning discharges in three spatial dimensions and time. The observations are found to reflect the basic charge structure of electrified storms. Observations have also been obtained of a distinct type of energetic discharge referred to as positive bipolar breakdown, recently identified as the source of trans-ionospheric pulse pairs (TIPPs) observed by satellites from space. The bipolar breakdown has been confirmed to occur between the main negative and upper positive charge regions of a storm and found to be the initial event of otherwise normal intracloud discharges. The latter is contrary to previous findings that the breakdown appeared to be temporally isolated from other lightning in a storm. Peak VHF radiation from the energetic discharges is observed to be typically 30 dB stronger than that from other lightning processes and to correspond to source power in excess of 100 kW over a 6 MHz bandwidth centered at 63 MHz.
Chapter 13: Space- and Ground-Based Studies of Lightning Signatures
2009
This article provides a brief survey of the space-and ground-based studies of lightning performed by investigators at Los Alamos National Laboratory (LANL). The primary goal of these studies was to further understand unique lightning signatures known as Narrow Bipolar Events (NBEs). First, an overview is presented of the Fast On-orbit Recording of Transient Events (FORTE) satellite and of the ground-based Los Alamos Sferic Array (LASA). This is followed by a summary of the phenomenology, physics, and meteorological context of NBEs and NBE-related discharges. This article also discusses additional radio frequency and optical observations of lightning made by the FORTE satellite and concludes with an outlook on LANL's growing interest in the use of lightning observations in the study of severe weather and hurricane intensification.
Journal of Geophysical Research: Atmospheres
This study compared the detection capabilities of the Geostationary Lightning Mapper (GLM) and ground-based Earth Networks Total Lightning Network (ENL) over the contiguous United States (CONUS) from 25 April 2017 to 5 May 2018. GLM detection efficiency (DE) relative to ENL varied spatially with greater DE in the southeastern United States and lower DE in the Northern Plains. Regions with greater DE were often regions where most intracloud flashes had normal positive polarity, while lower DE regions frequently had inverted negative intracloud. According to the tripolar noninductive charging model, inverted intracloud flashes are lower altitude than normal intracloud flashes. This lower altitude flash may result in greater cloud scattering of the optical lightning signal, which at cloud top is less than the GLM detection limits. DE was generally also greater for greater absolute peak current flashes, which serves as a proxy for optical energy. Additionally, GLM observed flashes to be generally greater in area and duration in the eastern relative to the western CONUS, which may result in the greater DE. GLM DE was also varied with the solar zenith angle as greatest DE occurred at night. ENL DE relative to GLM was varied spatially over CONUS with greater DE over eastern CONUS. ENL DE was greater for flashes of greater GLM flash radiant energy, area, and duration. 1.1. Lightning and Electrical Charging Proper evaluation of GLM and its detection necessitates understanding the cause of lightning and lightning characteristics. Noninductive charging (NIC), resulting from collisions of ice hydrometeors in the presence of supercooled water, likely represents the primary mechanism for electrical charging and the production of lightning in storms (Saunders et al., 2006). Charging of hydrometeors can be either positive or negative, with differences in charge partially neutralized by lightning discharges after sedimentation of charged hydrometeors. Stronger updrafts in the mixed-phase region (0°C to approximately −40°C) generally produce more charging and more frequent lightning flashes that are smaller and weaker (Bruning & MacGorman, 2013; Mecikalski et al., 2015). At warmer temperatures (e.g., 0°C to −10°C), graupel hydrometeors are positively charged during riming collisions, while ice particles are negatively charged. At cooler temperatures (e.g., −20°C to −40°C), graupel charges negatively, while ice hydrometeors charge positively. Since graupel is heavier relative to ice, a lowest positive-charged layer will generally form, while negatively charged ice particles are lofted to near negatively charged graupel, forming a negatively charged layer above the lowest positively charged layer. The positively charged ice is lifted upward to form an upper layer of positive charge. This forms the typical tripolar model of charging and lightning formation (see Figure 1 of Williams (1989) for further illustration). Examination of electric field data from balloons released into 33 thunderstorms indicates that the tripolar structure is generally observed in the updraft core (Stolzenburg et al., 1998).
A Review of Operational Lightning Detection: Comparison of Ground vs. Satellite-based Observations
Lightning generated by convective storms, and identified as a formidable hazard to life and property, results from strong storms lofting liquid-phase hydrometeors to high altitudes where freezing occurs and collisions between drops, graupel, and ice crystals lead to electrification. Among the most widely accepted theories of convective storm electrification is the " charge transfer-separation process " by which interaction (esp. collision) between ice crystals and graupel particles result in the establishment and stratification of positive and negative charge centers within the convective cloud, respectively. Differing growth processes between ice crystals (i.e. deposition of water vapor) and graupel (accretion of supercooled water) result in differing molecular structure and electron arrangement, and subsequently, favor the transfer of electrons with negative charge from an ice crystal to a graupel particle. In general, negative charge accumulates in the middle levels of the convective storm cloud, referred to as the " main negative charge " charge center, while positive charge accumulates in the upper layer and anvil (if present) region and is referred to as the " upper positive charge " center. Other secondary charge centers may develop in a convective storm, such as the " lower positive charge " center that results from falling hail, however, the main electric field built within the storm results from the separation of the main negative and upper positive charge centers. When the electric field strength (E) between the storm cloud and the ground eventually increases to the threshold value of electric breakdown potential (3 x 10 9 V/km), a stepped leader, defined as a segmented ionized channel, develops and propagates downward toward the ground in steps of 50 to 100 m length. Upon contact of the stepped leader with the ground, a bright return stroke from the ground to the cloud occurs, in which electrons flow downward from progressively higher levels in the channel. The stepped leader and return stroke comprise the lightning strike. The strike with additional return strokes, triggered by a dart leader, then comprise the cloud-to-ground (CG) lightning flash. Intracloud (IC) lightning discharge between the main negative and upper positive charge centers also results from charge separation and electrical breakdown. Ground-based and satellite-based lightning detection systems often detect both IC and CG lightning flashes, with CG strokes a stronger emitter of low frequency (LF) radiation. Lightning detection systems (LDS) have a vital role in the real-time identification of the location of lightning strokes for the purpose of public safety and weather forecasting and warning operations. Archived LDS datasets also provide support to electric utility companies to identify lightning events associated with electric power grid faults and power outages, reduce frequency and duration of power outages, and make improvements to transmission line segments susceptible to lightning damage. More importantly, flash rate and density measurements are necessary for the inference of cloud thermodynamical and microphysical processes that favor severe thunderstorm hazard phenomena including hail, tornadoes, and damaging winds (downbursts).
Revisiting Lightning Activity and Parameterization Using Geostationary Satellite Observations
Remote Sensing
The Geostationary Lightning Mapper (GLM) on the Geostationary Operational Environmental Satellite 16 (GOES-16) detects total lightning continuously, with a high spatial resolution and detection efficiency. Coincident data from the GLM and the Advanced Baseline Imager (ABI) are used to explore the correlation between the cloud top properties and flash activity across the continental United States (CONUS) sector from May to September 2020. A large number of collocated infrared (IR) brightness temperature (TBB), cloud top height (CTH) and lightning data provides robust statistics. Overall, the likelihood of lightning occurrence and high flash density is higher if the TBB is colder than 225 K. The higher CTH is observed to be correlated with a larger flash rate, a smaller flash size, stronger updraft, and larger optical energy. Furthermore, the cloud top updraft velocity (w) is estimated based on the decreasing rate of TBB, but it is smaller than the updraft velocity of the convective c...
Physics of lightning: new model approaches and prospects of the satellite observations
Physics-Uspekhi, 2018
Contents 1. Question of lightning initiation and evolution and new observation possibilities 766 2. Satellites as unique instruments for detecting lightning discharge radiation 769 3. New approaches in the lightning discharge theory 772 3.1 Lightning initiation as a noise-induced kinetic transition; 3.2 Lightning discharge as a fractal dissipative structure; 3.3 Compact intracloud discharge model as an example of applying a new approach for describing discharge phenomena 4. Conclusions 776 References 778