Status of Ground Flash Fraction Retrieval Algorithm Dr. William Koshak, NASA-MSFC - PowerPoint PPT Presentation

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Status of Ground Flash Fraction Retrieval Algorithm Dr. William Koshak, NASA-MSFC

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  1. Status of Ground Flash Fraction Retrieval Algorithm Dr. William Koshak, NASA-MSFC GLM Science Meeting Huntsville, AL September 19, 2012

  2. Space Shuttle Video (STS-48)

  3. Algorithms Use Maximum Group Area (MGA) to retrieve Ground Flash Fraction (α)

  4. GLM Observes a Mixture of CG and IC MGAs 1000 CGs 4000 ICs 5000 total + = (Observe) Retrieve characteristics about these. INVERT Three Basic Algorithms: Simple: Bayesian: Perturbation Methods:

  5. The pathway to the Analytic Perturbation Method

  6. MIX

  7. (Actual) (Dynamic Model)

  8. BASIC PERTURBATION METHOD (Vary both d and e) Find that minimizes:

  9. QUASI-ANALYTIC PERTURBATION METHOD (Vary just e; d obtained analytically) So force lives in (u, v) plane

  10. ANALYTIC PERTURBATION METHOD (d and e obtained analytically) Define: But: Hence: Where: Find ethat minimizes H: Substitute optimal eback into expression for H: … Quick plot of H vs. provides the solution (i.e. value of than minimizes H)

  11. RETRIEVAL ERRORS Using OTD Data Using LIS Data • Sampling from population [to create climate (a, b)]: • Ng = 40,000 flashes • Nc = 120,000 flashes • Z = Nc/Ng = 3

  12. Thank You (Questions?)