2nd meeting | Understanding The Properties Of The Terrestrial Gamma-Ray Flash Population

The meeting was held at ISSI Bern during week 24, 13 – 17 June 2022.

In addition to the official Team members, the discussion included the following young scientists (attending on site):
- Ingrid Bjørge-Engeland, Birkeland Centre for Space Science, University of Bergen, Norway
- Federica Defranchi Bisso, Technical University of Denmark, Denmark
- Pierre Gourbin, University of Orleans, France
- John Ortberg, University of California – Santa Cruz, USA
And the following researchers and young scientists from the Team members Institutions (attending online):
- Brant Carlson, Cartage College, USA
- Nikolai Lehtinen, Birkeland Centre for Space Science, University of Bergen, Norway
- Stephen Lesage, University of Alabama – Huntsville, USA
- David Sarria, Birkeland Centre for Space Science, University of Bergen, Norway
- Anthony Schmalzried, CSIC – Instituto de Astrofisica de Andalucia, Spain
- Chris A. Skeie, Birkeland Centre for Space Science, University of Bergen, Norway

Agenda:

Monday 13/06 – start 14:30.
- M. Sargent – Welcome to ISSI!
- M. Marisaldi – Introduction – project status
- Space mission status / TGF catalogs
  - M. Briggs – The new Fermi TGF catalog
  - M. Marisaldi – The updated AGILE TGF catalog
  - A. Mezentsev – Properties of ASIM TGFs
- Discussion: review paper update

Tuesdays 14/06 – start 09:00.
- Aircraft / balloon missions
  - S. Celestin – The OREO balloon mission
  - N. Østgaard – The ALOFT flight campaign
- Ground observations / new facilities
  - J. Ortberg – ground measurements in Europe and Japan
  - D. Smith – instrument design for ground measurements
  - A. Ursi – ground observations in Italy: the Gamma-Flash project
- Theory and modeling developments
  - J. Dwyer – Downward TGFs; TGFs from positive leaders; Optical emissions associated with TGFs; Current pulses associated with TGFs
  - P. Gourbin – self-consistent modeling of RREAs and associated radio emissions

Wednesday 15/06 – start 09:00
- Theory and modeling developments (continued)
  - A. Luque – Montecarlo methods and computation of cross-sections for runaway acceleration
  - C. Köhn – TGF production between approaching streamer coronae
  - D. Sarria – Library of gamma-ray glows and application to previous observations
- TGF science hot topics #1: TGFs and radio
  - S. Cummer – radio measurements associated to ASIM TGFs
  - A. Mezentsev – lightning activity associated to the Tonga eruption
  - M. Briggs – special TGF talk
- TGF science hot topics #2: TGF and optical emission
  - I.Bjørge-Engeland – TGFs with accompanying ELVEs
  - C. A. Skeie – temporal relationship between TGF and optical pulses
  - A. Mezentsev – Discerning TGF and leader current pulse in ASIM observation

Thursday 16/06 – start 09:00
- TGF science hot topics #3: Multi pulse TGFs
  - N. Østgaard – Multi-pulse TGFs with ASIM
  - M. Marisaldi – Multi-pulse TGFs with AGILE
- Mission concepts: new instruments / multi-spacecraft observations of TGF
  - E. Grove – New space instrumentation
  - M. Marisaldi – ASIM, Fermi, AGILE simultaneous observations of TGF
  - M. Briggs – the TRYAD mission
  - S. Celestin – the BEES mission concept
- Discussion: science requirements for a new TGF mission
- Discussion: funding opportunities in EU / USA and possible proposals