SOO-MERLIN_Low_DE_(25Jul19).pdf

STATEMENT OF OBJECITVES

FOR

LOW DETECTION EFFICIENCY OF MERLIN FOR LIGHTNIGN STRIKES TO TALL STRUCTURES AND/OR

LARGE CATENARY WIRE LIGHTNIGN PROTECTION SYSTEMS

(25 Jul 2019)

1. Title: Low Detection Efficiency of MERLIN for lightning Strikes to Tall Structures and/or Large Catenary Wire Lightning Protection Systems

2. Definition/Acronyms:

a. MERLIN – Mesoscale Eastern Range Lightning Information Network; the local lightning locating system used by the 45th Weather Squadron.

b. Detection Efficiency – the frequency of lightning events that is detected and reported by lightning locating systems.

c. Catenary Wire Lightning Protection System – Overhead hanging wires that protect the area beneath them from lightning by intercepting lightning about to strike and diverting the current into an electrical grounding system.

d. CG – Cloud-to-ground, as in cloud-to-ground lightning

e. CCAFS – Cape Canaveral Air Force Station located on the coast of east central Florida

f. KSC – Kennedy Space Center adjacent to CCAFS on the coast of east central Florida

g. SLC – Space Launch Complex

3. Background: In general, MERLIN (Roeder and Saul, 2017) provides excellent cloud-to-ground lightning performance with CG flash detection efficiency over 99% and median location accuracy of about 60 m (Hill et al, 2016). However, there has been anecdotal evidence that CG strikes to tall structures and/or large catenary wire lightning protection systems have lower detection efficiency, perhaps as low as 75%. This apparent low detection efficiency may be due to the strikes being detected but not reported due to the MERLIN quality control algorithms due to the waveforms differing for normal CG strikes, or being wrongly classified as lightning aloft, or being reported with locations far away from the true location relative to the location error ellipses.

These large structures and/or large catenary wire systems include launch pads and other important facilities for which detecting and reporting CG lightning strikes is critical. Therefore, the purpose of this project is to determine if the detection efficiency for tall structures/large catenary wire systems is significantly lower than the detection efficiency for MERLIN CG strikes to nearby normal ground. The reports and all data collected in this study will be the property of the government, to include the dates, precise times and precise locations of the strikes, any electromagnetic waveforms and/or video records of the strikes, etc. The government shall provide the MERLIN observations required for this study as request by the vendor.

4. Description: Provide a study documenting the detection efficiency of MERLIN for cloud-to-ground return strokes to tall structures and/or large catenary wire lightning protection systems as compared to CG return strokes to ground. A minimum of 50 return strokes in 25 flashes is required for the study. We anticipate 3 years will be required. A statistical hypothesis test will be included in the study testing if the detection efficiency is different for strokes to tall structures/large catenary wire systems and strokes to ground, including the p-value for statistical significance. The candidate tall structures/large catenary wire systems are the launch pads at CCAFS (SLC-40 and SLC-37) and perhaps at KSC (SLC-39A, SLC-39B, SLC-41). We anticipate the study will require the installation of a temporary high-performance lightning location system to serve as ground-truth to verify the MERLIN performance. The U.S. Air Force will provide the MERLIN lightning solutions corresponding to the lightning events for comparison.

5. Deliverables: Written report documenting the development process and results. Interim reports will be provided after each lightning season (May-Sep) or as milestone number of strokes are analyzed (20, 35, and 50 return strokes).

6. References:

Roeder, W. P., and J. M. Saul, 2017: The new Mesoscale Eastern Range Lightning Information Network, 18th Conference on Aviation, Range, and Aerospace Meteorology, Paper-12.1, 22-26 Jan 2017, 14 pp.

Hill, J. D., C. T. Mata, W. P. Roeder, and A. Nag, 2016: Evaluation of the performance characteristics of MERLIN and NLDN based on two years of ground-truth data from Kennedy Space Center/Cape Canaveral Air Force Station, Florida, 26th International Lightning Detection Conference, 18-21 Apr 16, 11 pp.

Roeder, W. P., and J. M. Saul, 2017: The new Mesoscale Eastern Range Lightning Information Network, 18th Conference on Aviation, Range, and Aerospace Meteorology, Paper-12.1, 22-26 Jan 2017, 14 pp.