1. Refractivity During IHOP_2002
Tammy M. Weckwerth (NCAR/ATD), Crystalyne R. Pettet (NCAR/ATD), Frédéric Fabry (McGill University), ShinJu Park (McGill University) and James W. Wilson (NCAR/ATD)
Water Vapor Intercomparison Workshop, Boulder, 2-3 October 2003

2. Intercomparisons Fixed and mobile surface stations AERIBAGO SRL
Aircraft

3. Intercomparisons
Mean Bias Stn-Radar = 1.68 N units

4. Intercomparisons
Bias is not related to propagation effects since it’s not diurnally dependent
Bias is worse at higher humidities

5. Surface Station Intercomparisons

6. Surface Station Intercomparisons
Excellent correlations
Radar has negative bias

7. Mobile Mesonet comparisons
Correlation = 0.81

8. Correlation = 0.88

9. AERIBAGO comparisons Correlation=0.89 Correlation=0.75

10. SRL comparisons

11. UWKA comparisons
Correlation drop occurs between 358 m leg (0.96) and 673 m leg (0.74)
Correlation=0.93

12. Correlation=0.88

13. Summary
Radar Refractivity may be a proxy for water vapor during the warm season.
Radar Refractivity shows excellent correlation with surface station and aircraft refractivity.
Radar Refractivity has a low bias vs fixed surface stations
Vertical depth represented appears to be lower levels of the ABL (<~300 m?).
Horizontal resolution is approximately 4 km (although it sometimes appears better).

14. Ongoing Work Evaluate accuracy of low-level refractivity retrieval
Fixed and mobile mesonets
Plan to: Add GPS intercomparisons
Plan to: Add DRI MMR intercomparisons
Evaluate layer over which refractivity retrieval is representative
Aircraft in situ measurements
SRL intercomparisons
AERI intercomparisons
Plan to: Add Sounding & Dropsonde comparisons
Plan to: Add horizontal and vertical pointing airborne DIAL
Plan to: Add TAOS intercomparisons
Possibly add: MIPS profiling radiometer intercomparisons
Plan to: Evaluate two more days in detail

15. Comments and Suggestions?

16. 2 km
11 km
Correlation=0.88

17. S-Pol Refractivity Retrieval
Variations in q, T and p
Boundary detection
Advection
Pettet et al., next;
Fabry and Park, 1700
dryline
dryline
cool/moist
warm/dry

18. Refractivity: One Day After Heavy Rainfall Aircraft in-situ data
Northern edge of aircraft track Ts=45 deg C,
Theta60=307 K,
q60 = 8.5 g/kg
warm/dry
Southern edge of
aircraft track Ts=32 deg C,
Theta60=306.2 K, q60 = 11 g/kg
cool/moist

19. warm/dry
cool/moist

20. Surface station comparisons
Correlation = 0.99

21. Correlation = 0.92
Correlation = 0.98

22. Correlation = 0.14

23. Correlation = 0.68