Multiple Environmental Influences on the Lightning of Cold-Based Continental Cumulonimbus Clouds. Part I: Description and Validation of Model

Journal Article · Tue Dec 01 00:00:00 EST 2020 · Journal of the Atmospheric Sciences

DOI:https://doi.org/10.1175/jas-d-19-0200.1· OSTI ID:1784527

Phillips, Vaughan J. ^[1]; Formenton, Marco ^[1]; Kanawade, Vijay P. ^[1]; Karlsson, Linus R. ^[1]; Patade, Sachin ^[1]; Sun, Jiming ^[2]; Barthe, Christelle ^[3]; Pinty, Jean-Pierre ^[4]; Detwiler, Andrew G. ^[5]; Lyu, Weitao ^[6]; Tessendorf, Sarah A. ^[7]

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1. Lund Univ. (Sweden)
2. Chinese Academy of Sciences (CAS), Beijing (China). Institute of Atmospheric Physics
3. Université de La Réunion, Saint Denis, Réunion, (France). Laboratoire de l'Atmosphère et des Cyclones; Météo-France, Paris (France)
4. Université Paul Sabatier and CNRS, Toulouse (France). Laboratoire d’Aérologie
5. South Dakota School of Mines and Technology, Rapid City, SD (United States)
6. Chinese Academy of Meteorological Sciences, Beijing (China). State Key Laboratory of Severe Weather
7. National Center for Atmospheric Research, Boulder, CO (United States)

In this two-part paper, influences from environmental factors on lightning in a convective storm are assessed with a model. In Part I, an electrical component is described and applied in the Aerosol–Cloud model (AC). AC treats many types of secondary (e.g., breakup in ice–ice collisions, raindrop-freezing fragmentation, rime splintering) and primary (heterogeneous, homogeneous freezing) ice initiation. AC represents lightning flashes with a statistical treatment of branching from a fractal law constrained by video imagery. The storm simulated is from the Severe Thunderstorm Electrification and Precipitation Study (STEPS; 19/20 June 2000). The simulation was validated microphysically [e.g., ice/droplet concentrations and mean sizes, liquid water content (LWC), reflectivity, surface precipitation] and dynamically (e.g., ascent) in our 2017 paper. Predicted ice concentrations (~10 L^-1) agreed—to within a factor of about 2—with aircraft data at flight levels (-10° to -15°C). Here, electrical statistics of the same simulation are compared with observations. Flash rates (to within a factor of 2), triggering altitudes and polarity of flashes, and electric fields, all agree with the coincident STEPS observations. The “normal” tripole of charge structure observed during an electrical balloon sounding is reproduced by AC. It is related to reversal of polarity of noninductive charging in ice–ice collisions seen in laboratory experiments when temperature or LWC are varied. Positively charged graupel and negatively charged snow at most midlevels, charged away from the fastest updrafts, is predicted to cause the normal tripole. Total charge separated in the simulated storm is dominated by collisions involving secondary ice from fragmentation in graupel–snow collisions.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Atmospheric Radiation Measurement (ARM) Data Center
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER); National Science Foundation (NSF); Swedish Research Council (SRC)
• Contributing Organization: Pacific Northwest National Laboratory (PNNL); Brookhaven National Laboratory (BNL); Argonne National Laboratory (ANL)
• Grant/Contract Number: SC0018932; SC0018967
• OSTI ID: 1784527
• Journal Information: Journal of the Atmospheric Sciences, Vol. 77, Issue 12; ISSN 0022-4928
• Publisher: American Meteorological Society
• Country of Publication: United States
• Language: English

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54 ENVIRONMENTAL SCIENCES