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. + = 1000 CGs4000 ICs5000 total Three Basic Algorithms: Simple: Bayesian: Perturbation Methods: Retrieve characteristics about these. INVERT (Observe) GLM Observes a Mixture of CG and IC MGAs

6. The pathway to the Analytic Perturbation Method

7. MIX

8. (Actual) (Dynamic Model)

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

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

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

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

14. Thank You (Questions?)