What does Total Lightning mean anyway?
You have probably heard the term “total lightning,” but do you know what it really means? In short, it means the detection of both cloud lightning and cloud-to-ground lightning, giving us a more complete view of the activity in a storm. The study of cloud lightning is bringing scientists new research data and is allowing meteorologists to understand better the relationship between lightning and severe weather.
Cloud-to-ground lightning has been extensively studied for decades, and private companies like Vaisala are continuing to perfect the accuracy of location and timing of these strikes. After all, cloud-to-ground lightning directly affects the places where we live and work – from disrupting electric power systems to impacting recreation and travel. Accurately detecting cloud-to-ground lightning allows us to be prepared, stay safe, and operate weather critical business efficiently during adverse weather. Through the study of lightning, lessons have been learned that there is an association between cloud lightning and severe weather, including the threat of high winds, hail, and wind-shear. Also, as forecasting techniques evolve, there is increasing value in detecting both cloud and cloud-to-ground lightning with higher quality. However, differentiating between these two types of lightning is extremely important in certain critical operations. For example, reliable identification of cloud-to-ground lightning is essential in electric power transmission management. In addition to differentiation, uniform detection capability is key to assessing storm development and the potential for severe weather, where the rate of total lightning and the ratio of cloud lightning to cloud-to-ground lightning are thought to be key factors.
Detecting Cloud and Cloud-to-Ground Lightning
Lightning detection systems detect electromagnetic pulses emitted by lightning discharges. Vaisala’s LS7000 series sensors are engineered to detect the Very Low Frequency (VLF) and Low Frequency (LF) signals emitted by cloud-to-ground lightning strikes and cloud pulses. This frequency range is optimal for detecting and classifying these lightning discharges over long distances, which allows Vaisala to design networks that have 70% fewer sensors than required with any other technology and, at the same time, provide industry leading performance and uniform coverage over wide areas. Vaisala’s approach to detecting lightning is to develop technology that delivers only data that is assessed, with a high degree of certainty, as being either cloud-to-ground or cloud lightning, and Vaisala is the first company to resolve the problem of properly classifying cloud lightning and cloud-to-ground lightning. Using technology developed for the Vaisala Thunderstorm Advanced Total Lightning Sensor LS7002, Vaisala is able to bring accurate total lightning to its users with improved sensitivity to detect weaker cloud pulses. This technology furthers the capability to discriminate correctly between cloud-to-ground and cloud lightning, while significantly increasing the amount of cloud lightning reported.
Correct Classification of Lightning is Important
Where lightning data plays a role in your decision-making process it is important to make sure you are getting accurate information, not just “dots on a map”. High data quality ensures you have a trustworthy source of information for weather models, forecasting, advance warnings, safety, operational efficiency and asset monitoring. There are three important performance considerations when selecting a lightning network. The first is to detect as much lightning as possible within the network and in the immediate vicinity. This capability is known as high detection efficiency. A cloud-to-ground or cloud flash is said to be “detected” if one or more of the pulses in the flash are detected and reported by the lightning network. The second is to determine the positions of individual lightning discharges as accurately as possible, or in other words, ensure location accuracy is at the highest level. The location accuracy of a network is particularly important for cloud-to-ground strikes.
Vaisala uses Combined Technology - magnetic direction finding and advanced time-of-arrival - to provide accurate locations of both cloud-to-ground and cloud lightning. This patented approach to lightning detection provides the major benefit of delivering accurate lightning locations, while maintaining a high detection efficiency, with far fewer sensors than any other method. The third is the proper classification of lightning – was it cloud lightning, or cloud-to-ground lightning? It is well known that most of the lightning occurring in a storm is cloud lightning, and while detecting both types is readily accomplished, it is much more challenging to provide a clean dataset with a high degree of classification accuracy.
Any lightning network can claim to provide total lightning, but what are you really getting? Total lightning counts alone do not provide the best or most complete information. Proper classification requires using sensor technology that intelligently detects and filters the signals, together with advanced algorithms that properly differentiate cloud lightning and cloud-to-ground lightning. In lightning detection, as in all aspects of weather observation, it is of utmost importance to Vaisala that customers are always getting the most accurate weather information in a timely and cost-effective manner, weather information that can be relied on.