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Lightning NOx Estimates from Space-Based Lightning Imagers

Dr. William Koshak from NASA/MSFC presents a method for estimating LNOx by using observed optical energy to infer total flash energy and then multiplying it by thermo-chemical yield. The presentation covers topics such as flash optical energy determination, correcting sensor data, and the impact of drought years. The study uses data from the TRMM/LIS satellite to analyze the production of LNOx per flash and how it varies throughout different seasons and climate conditions. Monthly trends in LNOx production are discussed, showing peaks in summer months due to changes in flash count. Overall, the research provides valuable insights into understanding and estimating NOx emissions using satellite imagery data.

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Lightning NOx Estimates from Space-Based Lightning Imagers

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  1. Lightning NOx Estimates from Space-Based Lightning Imagers Dr. William Koshak (NASA/MSFC) 16th Annual CMAS Conference, Chapel Hill, NC 25 October 2017

  2. Basic idea: Use observed optical energy to infer total flash energy E … then multiply by thermo-chemical yield to get LNOx. Koshak, NASA/MSFC

  3. What to use for Flash Optical Energy? Koshak, NASA/MSFC

  4. to sensor isotropy assumed (pixel footprint) Upward flux density from pixel footprint for ithframe Koshak, NASA/MSFC

  5. Tiny Fraction of E Reaches Sensor Koshak, NASA/MSFC

  6. Correcting for LIS sensitivity roll-off In dataset Off Boresight Angle (degrees) • Derived from: Boccippio, D. J., W. J. Koshak, R. J. Blakeslee, Performance assessment of the Optical Transient Detector and Lightning Imaging Sensor. Part I: predicted diurnal variability, J. Atmos. Oceanic Technol., 19, 1318-1332, 2002. Koshak, NASA/MSFC

  7. What do you do for GLM ? LIS [μJ m-2 sr-1 nm-1] GLM [ μJ ] Koshak, NASA/MSFC

  8. LNOx production from kth flash Koshak, NASA/MSFC

  9. LNOx Production for a region/period this estimative term not needed for GLM since GLM continuously monitors (observed + unobserved) Koshak, NASA/MSFC

  10. TRMM/LIS Mean Q per flash (fJ/flash) drop mostly from orbit boost drought year • 2014 added to the record • 2015 partial year + issues, so not used • Generally a downward trend (drop in 2001 mostly due to orbit boost) • Upward trend starting in 2011 • Strong increase in 2012 drought (these are per flash results) Koshak, NASA/MSFC

  11. TRMM/LIS Mean 𝛤𝜆𝛥𝜆 per flash ≡ ℇ (mJ/flash) drought year orbit boost bias removed • Monthly Plots: Maxima occurs in Januarybut this is all normalized (i.e. per flash values) • Jan max possibly indicative of large current +CGs and/or small vertical optical depth, common in winter thunderstorms. Koshak, NASA/MSFC

  12. TRMM/LIS Mean LNOx Production per flash ≡ 𝜦 (moles/flash) drought year Koshak, NASA/MSFC

  13. TRMM/LIS LNOx Production P (megamoles) drought year • Since this is total LNOx production, time-series trends are now modulated by the flash count … so peaks are in the summer months (see monthly plot). • Previous plots were normalized wrt flash count. Koshak, NASA/MSFC

  14. Thank You Koshak, NASA/MSFC

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