NSSL works to develop an understanding of how storms produce lightning and what the lightning data reveals about the microphysics, kinematics, and severity of storms. This information is used to help develop methods for using lightning data to improve forecasting and nowcasting of storms and storm hazards.
Lightning Research Areas
NSSL is working to understand how electrical charges are distributed in a thunderstorm. We use instrumented balloons to collect storm electricity data and other atmospheric variables as they rise into the storm. This will help us learn how lightning and other electrical storm properties are dependent on storm structure, updrafts and precipitation.
Oklahoma Lightning Mapping Array (OKLMA)
The Oklahoma Lightning Mapping Array (OKLMA) provides three-dimensional mapping of lightning channel segments over Oklahoma. Up to thousands of points can be mapped for an individual lightning flash, to reveal its location and the development of its structure. We are investigating how lightning characteristics relate to updrafts, precipitation and severe storm processes, and how to use lightning data in weather forecast models.
By studying lightning mapping data, we are learning how changes in lightning behavior can be associated with different types of storms and be an alert to forecasters that severe weather is developing. Lightning mapping has shown that some supercell thunderstorms have “lightning holes” where updrafts are located and precipitation is scarce, just before a storm becomes severe. This information could alert forecasters to developing severe conditions.
We have demonstrated that rapid increases in total lightning activity are often observed tens of minutes in advance of the occurrence of severe weather at the ground. These rapid increases in lightning activity have been termed “lightning jumps.” The overall goal of our study is to advance the development of an operationally applicable lightning jump algorithm that can be used with either total lightning observations made from the ground, or in the near future from space using the Geostationary Operational Environmental Satellite Series R (GOES-R) Geostationary Lightning Mapper.
Since lightning observing networks are sparse, scientists are generally limited to analyzing photographs of flashes of lightning channels exiting the cloud. NSSL has a 3D lightning model to simulate lightning flashes within modeled storms with realistic charge distributions at resolutions as fine as 25 meters. They can make comparisons between simulated and observed flashes, and analyze lightning more closely.
Lightning and Thunderstorm Relationships
The NSSL Field Observing Facilities and Support group (FOFS) has built a special balloon-borne instrument called a Particle Imager, designed to capture high-definition images of water and ice particles as it is launched into, and rises up through, a thunderstorm. The instrument is flown as part of a “train” of other instruments connected one after another to a balloon. These other instruments measure electrical field strength and direction, and other important atmospheric variables such as temperature, dewpoint, pressure and winds. Data from these systems helps researchers understand the relationships between the many macro and microphysical properties in thunderstorms.
Satellite Lightning Detection
The Geostationary Operational Environmental Satellite-R Series (GOES-R) is the next generation of geostationary weather satellites, scheduled to launch in 2015. This satellite will be equipped with a Geostationary Lightning Mapper (GLM) that will detect both cloud-to-ground and inter-cloud lightning. This will help severe weather forecasters identify thunderstorms which are rapidly intensifying, and enable them to issue accurate and timely severe thunderstorm and tornado warnings.
NSSL partners in the GOES-R Proving Ground, a unique opportunity to interact with and study new products available from GOES-R satellite. The GOES-R PG environment provides forecasters with the knowledge, training and experience needed to effectively use the products in day to day operations once they become available.
Pseudo-Geostationary Lightning Mapper (PGLM) is the primary lightning training tool for the GOES-R program in preparation for the launch of the Geostationary Lighting Mapper (GLM). It uses total lightning data from three Lightning Mapping Array (LMA) networks and the Lightning Detection and Ranging network that detects VHF radiation from lightning charges. The flashes are sorted, and a Flash Extent Density product is created.
Predicting Lightning Threats
Collaborators are using NSSL's research forecast model to ingest PGLM data for very short-range (0 to 60 minute) forecasts of severe weather events. Forecast models that are able to ingest Doppler radar, lightning or satellite data of thunderstorms provide improved predictions of thunderstorms and their associated severe weather.
In the NOAA Hazardous Weather Testbed (HWT), NSSL partners with the SPC and NWS to develop, test and evaluate severe weather forecast and warning techniques for the entire United States. The cornerstone of the HWT is the Spring Experiment held each year during the active spring severe weather season. The exchange provides forecasters with a first-hand look at the latest research concepts and products, while research scientists gain valuable understanding of the challenges, needs and constraints of front-line forecasters.
Storm Electricity Research Partnerships
NSSL works with NASA's Short-term Prediction Research and Transition (SPoRT), the Cooperative Institute for Meteorological Satellite Studies (CIMSS), New Mexico Institute of Mining and Technology (NMIMT), the Cooperative Institute for Research in the Atmosphere (CIRA) and the NOAA National Environmental Satellite, Data and Information Center (NESDIS), in addition to working closely with the NOAA Storm Prediction Center (SPC) and the NOAA National Weather Service (NWS).
Past Lightning Research
The Deep Convective Clouds and Chemistry (DC3) field experiment investigated thunderstorms using aircraft and ground-based instruments. This data will help us understand how thunderstorm updrafts carry electrically charged particles, water vapor and other chemicals to other parts of the atmosphere.
Mobile Ballooning Facility
NSSL developed the first truly mobile ballooning facility for obtaining upper-air soundings of the atmosphere. Researchers modified a 15-passenger van by mounting a Cross-Chain Loran Atmospheric Sounding System inside, and invented a high-wind launch device for releasing helium-filled balloons in very high winds. This pioneering capability allowed NSSL to take upper-air soundings in the vicinity of tornadoes and drylines, gathering critically needed observations in the near-storm environment of thunderstorms. In addition, these mobile labs and ballooning systems provided the first vertical profiles of electric fields inside a thunderstorm leading to a new conceptual model of electrical structures within convective storms.
Field experiments involving numerous mobile instruments with a primary focus on atmospheric electricity included:
- MEaPRS, the MCS Electrification and Polarimetric Radar Study designed to investigate polarization radar signatures and electrification processes in MCS's
- STEPS, the Severe Thunderstorm Electrification and Precipitaiton Study to make meteorological and electrical observations of supercell thunderstorms
- TELEX, the Thunderstorm Electrification and Lightning EXperiment to learn how lighting and other electrical storm properties are dependent on storm structure, updrafts, and precipitation.
The Electrical Nature of Storms
NSSL's Don MacGorman and Dave Rust wrote The Electrical Nature of Storms, a textbook discussion of atmospheric electricity and the electrical processes that occur in storms.
NSSL researchers were active in promoting lightning safety education. One reason for this is that lightning is a single-victim event, unlike flash flooding which can kill many people at one time. Since it is not possible to issue specific warnings for every lightning flash for each person, researchers feel compelled to provide tools to help people protect themselves from lightning danger.
NSSL's scientists and collaborators did a study to find out how close is “too close” for lightning. They found that 80% of the next lightning strikes in a storm are within 2 to 3 miles of each other in certain weather conditions in Florida, but more typically lightning strikes are about 6 miles from each other. Their research was incorporated into a paper on updated recommendations for lightning safety which set forth some simple concepts for lightning safety (2002).
Taking shelters under trees is dangerous - recent studies of lightning victims showed several highly-vulnerable situations and activities, but the one that stood out was taking shelter under trees. NSSL scientists developed posters on this threat, called “LIGHTNING DANGER! STAY AWAY FROM TREES DURING THUNDERSTORMS!” Over 16,000 copies have been printed in English and Spanish. The posters were distributed to teachers, NWS staff, and others.
NSSL scientists gave valuable input to the NCAA Committee on Competitive Safeguards and Medical Aspects of Sports as they developed guidelines for lightning safety at NCAA sporting events. They also helped create a position statement regarding lightning safety for athletics and recreation for the National Athletic Trainers' Association
NSSL/CIMMS scientists simulated realistic cloud-to-ground lightning flashes for the first time using a 3-D cloud model that generates complex precipitation such as graupel (soft hail), which is known to affect lightning production.
NSSL scientists have reported on the climatologies of lightning in different states including AZ, FL, GA, SC, NM, KS, CO, and OK.
NSSL worked with the NWS to carefully evaluate the performance on the WSR-88D lightning protection system and make recommendations for improvement. Part of the process included creating a 3-D computer simulation of a cloud-to-ground lightning stroke striking a radar antenna tower.