Preliminary Evaluations of Using Lightning Data to Improve Oceanic Convective Forecasting for Aviation

The National Weather Service (NWS) Aviation Weather Center (AWC) has developed a new product that overlays "long-range" lightning data onto InfraRed (IR) satellite imagery. These lightning data are an extension of the National Lightning Detection Network (NLDN) developed and operated by Global Atmospherics, Inc. (GAI), and the Canadian Lightning Detection Network (CLDN) owned by Environment Canada. The Federal Aviation Administration (FAA) and the NWS are promoting an evaluation of this product under the National Lightning Contract between the NWS and GAI, with participation from Government (NWS, FAA, and Department of Defense (DoD)) as well as non-Government users (airline meteorologists) for a limited evaluation period (April to December 1999). The primary purpose of this evaluation is to determine whether this experimental data aids in convective oceanic forecasting. Since this data set also provides information not available elsewhere, it has the potential to contribute to improved safety and cost savings. In addition, this assessment should establish if the value of this experimental lightning product is sufficient to 1) develop a need for routine access to the data, and 2) explore the possibilities of extending the sensor network to mitigate the diurnal ionospheric effects and increase the data availability.

There is large difference in long-range NLDN/CLDN detection between day and night due to diurnal influences on the ionosphere. During the day, the long-range lightning data are generally available out to 2000 km from the Continental US. At night the range extends beyond 4000 km. GAI is coordinating this experiment with the owners of sensor networks in Europe, Brazil and Japan, for the subsequent integration of their data with the U.S. and Canadian lightning detection network data sets. This will "extend the hours of darkness" with improved detection and location accuracy, as well as provide data from the other sides of the Atlantic, Pacific, and tropical ocean regions. There are five regions and corresponding products for the evaluation: 1) The Atlantic (Central US to Central Europe), 2) The Pacific (Western US to Japan), 3) The Tropical (Southern US to Brazil), 4) Gulf of Mexico (US coast to South American coast), and 5) Western Atlantic (Central US to middle of the Atlantic).

When the long-range lightning data are superimposed on satellite imagery, one can discern which clouds contain convective activity. It would appear that this product could be of value to the Central Weather Service Unit (CWSU) meteorologists at the Air Route Traffic Control Centers (ARTCCs), especially those with oceanic responsibilities (i.e., Oakland, New York, Miami, and Jacksonville); the meteorologist at the Airline Operations Centers; and DoD personnel. Preliminary evaluations indicate that NWS and ARTCC meteorologists have found the data to be quite useful in their operations of issuing International Significant Meteorological Information (SIGMETs) for Convection and routing aircraft away from potentially hazardous thunderstorms over the oceans. Weather forecasters at NWS Forecast Offices in the Northwest have used NLDN data to track approaching convective storms in the coastal Eastern Pacific region. CWSU meteorologists and other ARTCC personnel have found these data beneficial in monitoring convective storm development over the Gulf of Mexico and the Caribbean. Further strengths and weaknesses of the data will be ascertained through this evaluation and suggestions will be solicited as to how the data could be made more useful.