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Autocorrelation of ABFM Measurements

Autocorrelation of ABFM Measurements. Francis J. Merceret NASA/YA-D 12 November 2002. Overview. Preliminary exploration only! 22 flights over 2000 and 2001 campaigns Electric field (GEmag) Radar (REAC) Cloud particle concentration (TotCon1DC) Sample sizes from 732 to 1600 per flight

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Autocorrelation of ABFM Measurements

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  1. Autocorrelation of ABFM Measurements Francis J. Merceret NASA/YA-D 12 November 2002

  2. Overview • Preliminary exploration only! • 22 flights over 2000 and 2001 campaigns • Electric field (GEmag) • Radar (REAC) • Cloud particle concentration (TotCon1DC) • Sample sizes from 732 to 1600 per flight • Lagged from -20 to 20 records (10s per record)

  3. Nice Example - 010604

  4. Scary Example - 010625

  5. E-Field Composite

  6. Radar Composite

  7. Cloud Composite

  8. “Effective Sample Size” • Autoregressive model rxx(k) = fk • Nm= N (1-f); Ns=N (1-f2) • For mean or median of this sample, Nm /N = about 1/11 and Ns /N = about 1/6 for all three variables • For max of this sample, Nm /N = about 1/27 and Ns /N = about 1/14 for e-field and cloud and 1/37, 1/19 respectively for radar.

  9. Conclusion • Electric field, radar and 1DC concentrations are auto-correlated similarly • Effective reduction in sample size due to auto-correlation is roughly one order of magnitude

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