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Analysis of Refractivity Measurements: Progress and Plans

Analysis of Refractivity Measurements: Progress and Plans. Fr édéric Fabry McGill University Montré al, Canada. My IHOP-Related Objectives. Comparisons of moisture estimates with other sensors; Improvements to the refractivity extraction code; Case analyses.

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Analysis of Refractivity Measurements: Progress and Plans

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  1. Analysis of Refractivity Measurements: Progress and Plans Frédéric Fabry McGill University Montréal, Canada

  2. My IHOP-Related Objectives • Comparisons of moisture estimates with other sensors; • Improvements to the refractivity extraction code; • Case analyses.

  3. Comparisons of moisture estimates Refractivity data is only in NCAR’s possession; - buried within 1350 GB of S-Pol data files • that have become available only since January; downloadable a few GB a shot • I do not have most of the refractivity data • This aspect of the work has suffered

  4. Comparisons of moisture estimates Station data vs radar field average Refractivity Time

  5. Improvements to Refractivity Code Field code worked well, but difficult to use as a reanalysis tool. Three areas of focus: • Improve input data to algorithm (better calibration, more sophisticated data selection…); • Make it easier to change parameters; • Try a whole new data fitting algorithm using a variational approach.

  6. Improvements to Refractivity Code Field run New run • Sharper gradients, more noisy fields. • Artifacts no longer hidden by smoothing. • Also generated: Field of measurement error. • Rerun of IHOP campaign is in progress.

  7. Cases Analyses Current focus is on: • Structure of fronts (moisture vs wind fronts); • The nature of the many moisture discontinuities observed; • ABL, in particular the time evolution of moisture; • Bore cases; • The odd convection initiation (and lack of) near S-Pol.

  8. Examples: BL Moistening Rain accumulation two days before next event; foggy next day

  9. Examples: BL Moistening Sunny, cool, calm morning; will warm quickly Anomalous propagation echoes No wind (!) Maximizes local effects

  10. Q: Can the Moisture Flux Be Computed? Assuming vertical homogeneity: 5min Vertical advection (BL growth) Precipitable water change in BL Horizontal wind Advection From radar refractivity N Height of the Boundary Layer from FM-CWProfiler radar

  11. Q: Can the Moisture Flux Be Computed? from Sounding, FM-CW Radar, MIPS 13:52z 17:32z Mean Depth of MBL 1500 +++++ FM-CW +++++ MIPS 1000 AGL Height (m) 646m 500 Hour (UTC) q(g/kg) θv(K) V(m/s) take the FM-CW as representative of the whole domain

  12. Moisture Flux : Comparisons Radar ISFF ISFF  Time variability of humidity in the free atmosphere swamped the flux signal. Too bad…

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