1 / 21

Advancements in Ground Flash Fraction Retrieval Algorithms: Insights from GLM Science Meeting

This presentation by Dr. William Koshak at the GLM Science Meeting focuses on the Ground Flash Fraction Retrieval Algorithm. The talk explores the algorithm's application in improving air quality models and understanding the effects of lightning on global chemistry and climate models. It tackles the complexities of the inversion problem, examining the reconstruction of lightning channel intensity using historical data and advanced mathematical techniques. Key findings from past studies and the application of Bayesian inversion methods for flash-type discrimination are also discussed.

midori
Télécharger la présentation

Advancements in Ground Flash Fraction Retrieval Algorithms: Insights from GLM Science Meeting

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ground Flash Fraction Retrieval Algorithm GLM Science Meeting December 1-3, 2010, Huntsville, AL Dr. William Koshak, NASA/MSFC/VP61 photo by Chuck Doswell

  2. Desired Future Application # GLM Flashes Ground Flash Fraction Retrieval Algorithm (today’s talk) # GLM Ground Flashes # GLM Cloud Flashes MSFC LNOM (lightning NOx) Air Quality Models (e.g. CMAQ) Global Chemistry/Climate Models (e.g. GISS Model E, GeosChem)

  3. Algorithm is used to solve an Inversion Problem Unknown Measurements K (Kernel) (Footprints) (Dragon)

  4. What % Strike Ground?

  5. Consider a (linear) Optics Analog Mueller Matrix: A matrix which can be used to reproduce the effect of a given optical element when applied to aStokes vector. Source observer Optical Elements K Optical Element Mueller Matrix (Singular) Linear horizontal polarizer Right-handed circular polarizer

  6. In Reality: Multiple Scattering Medium

  7. Actual Forward Multiple Scattering Problem

  8. Eqs. (21) is the Forward Problem … it’s ugly. Inverse Problem is uglier.

  9. Is there a channel to ground? Formal Inverse Problem: Reconstruct Channel from Intensity

  10. Historical Recap • Several studied the forward problem • Thomason & Krider 1982 (Monte Carlo) • Koshak et al. 1994 (Boltzmann Diffusion) • Suszcynsky et al. 2000 (optical & vhf data, not theory) • Light et al. 2001 (Monte Carlo) • Davis & Marshak 2002 (Green’s functions) • Nobody published the inverse problem for channel • reconstruction; flash-by-flash-discrimination (FBFD) • Neural Net (Boccippio … unknown status); probabilistic FBFD • Bayesian Inversion (Koshak); ground flash fraction retrieval

  11. Bayesian Inversion

  12. Use just 1 physical parameter Find & examine the “group” in the flash having the Maximum Area.

  13. Distributions of the Maximum Group Area (MGA) Ground Flashes Cloud Flashes

  14. Shifted MGA y = MGA – 64 km2

  15. Retrieval Errors with Increasing N (N = # flashes observed)

  16. Improvements using Normal Priors P(α, µg , µc)= P(α)P(µg)P(µc) = 1·P(µg)P(µc) Priors P(µg) and P(µc) are Uniformly Distributed Priors P(µg) and P(µc) are Normally Distributed

  17. Retrieved Ground Flash Fraction

  18. For More Details … Koshak, W. J., Optical Characteristics of OTD Flashes and the Implications for Flash-Type Discrimination, J. Atmos. Oceanic Technol., 27, 1822-1838, 2010. (November issue) Koshak, W. J., R. J. Solakiewicz, Retrieving the Fraction of Ground Flashes from Satellite Lightning Imager Data Using CONUS-Based Optical Statistics, accepted in J. Atmos. Oceanic Technol., August 30, 2010. Koshak, W. J., A Mixed Exponential Distribution Model for Retrieving Ground Flash Fraction from Satellite Lightning Imager Data, accepted in J. Atmos. Oceanic Technol., August 30, 2010.

More Related