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
Precipitable water change in BL
Horizontal wind
Advection
Vertical
advection
(BL growth)
From radar refractivity N
Height of the Boundary Layer from FM-CW Profiler 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…