1. Overview of The International H2O Project (IHOP_2002)
David B. Parsons and Tammy Weckwerth
Co-lead Scientists
NCAR/ATD
Motivation and research goals
Preliminary highlights
Impacts and role of profiling

2. GENERAL MOTIVATION

3. Overall Goals
Improved understanding and prediction of warm season rainfall (0 –12 h forecast)
Improved characterization of the time varying 3-D distribution of water vapor
Four overlapping research components
Convective initiation
Quantitative precipitation forecast
Atmospheric Boundary Layer
Instrumentation (optimal mix)

4. Isentrophic Airflow and Sounding Domain
Isentropic streamlines (37 C) for 2330 UTC 4 May The dashed lines are
isobars at 100 hPa intervals (from Carlson and Ludlam 1968)

5. IHOP Summary: 13 May to 25 June
>200 Technical participants from the U.S., France, Germany and Canada
~2500 additional soundings
> 50 instrument platforms, 6 aircraft, 45 IOPs
268 h of airborne water vapor lidar measurements
76 h of airborne satellite evaluation measurements (S-HIS and NAST)
Dedicated GOES-11 data

6. IHOP_2002

7. IHOP Aircraft

8. Convective Initiation Flight Plan

9. Mobile Mesonet, Smart-R radar and Control Center

10. Convective
Initiation
of a flash
flood

11. Wyoming Cloud Radar (WCR) reflectivity profile above flight level, along a 22 km long transect from ESE to WNW on 24 May 2002 in northern Texas.

12. RESEARCH HIGHLIGHTS Session 6 1ST Session 2nd Session
Flamant et al. (bore)
Koch et al. (bore)
Whiteman et al. (SRL)
Browell et al. (LASE)
Demoz et al. (Dryline)
Hardesty et al. (Doppler and DLR DIAL)
Kiemle et al. (DLR DIAL)
Di Girolamo (Raman)
1ST Session
Gentry et al. (GLOW)
Geerts and Maio (bugs)
Yu et al. (MAPR-RIM)
2nd Session
Feltz et al. (AERI)
Flentje et al. (DLR DIAL on IHOP ferry flights)

13. RESEARCH HIGHLIGHTS Session 7 Session 6 (cont.)
Schwemmer et al. (HARLIE)
Session 6 (cont.)
Tarniewicz et al. (GPS, DIAL, NWP)
Lhomme et al. (LEANDRE DIAL)
Van Baelen et al. (GPS)
Wang (radiosonde and lidar)
Behrendt et al. (DIAL intercomparison)
Knuteson et al. (HIS)

14. 1st Research Example Radar Refractivity-
Current nowcasting systems use radar fine lines detected by reflectivity, future systems will rely heavily on radar refractivity!!
Developed by Fred Fabry (McGill)
Deployed on the NCAR’s S-band radar (S-Pol)
Analysis by Fabry, Weckwerth, Pettet et al.

15. Radar Measurements of Refractive Index
—— r n c
Target phase: Ф(r) = 2πf ttravel(r) =
For fixed targets, phase will change as n changes.

16. Real Time Display Example
Rapid moistening
Storm 60
Outflow
Wet
Diurnal cycle
(mostly)
Dry
Wet

17. IHOP Examples: Dry-Line Genesis5 10 7º
11º+ P3
Broad Td gradient; Hints of convergence

18. IHOP Examples: Dry-Line Genesis
Fine line appears
20:51 5 10 P3
Tight gradient moving
Tightening gradient

19. IHOP Examples: Dry-Line Evolution
Dry line splits
…As dry line moves west
To join back after…

20. Refractivity: One Day After Heavy Rainfall Aircraft In-situ data
Northern edge of aircraft track Ts=45,
Theta60=307,
q60 = 8.5
Southern edge of
aircraft track Ts=32,
Theta60=306.2, q60 = 11
Weckwerth
and LeMone
also Fabry

21. 2nd Research Example GOAL:
Attempt to answer the conundrum of why there is a nocturnal precipitation maximum over the Southern Great Plains when the convective stability should be less favorable.
Result:
Undular bore-like disturbances, thought to occur over this region on occasion, are common, tigger new convection and create a mesoscale environment favorable for deep convection.

22. IHOP_2002 Sounding Western OK 1730 pm LST
CAPE
CIN

23. Water Vapor: 20 June

24. BORE
Example
From
MAPR
4 June

25. “Surface”-based Parcel
20TH June
Unstable, capped env.
1730 pm
Dramatic stabilization,
expected due to radiational cooling !
0301 am
Very stable

26. In fact the parcels are easier to convect than
“Surface” and Inversion Parcels
0301 am
1730 pm
1730 pm
0301 am
Opposite trends
In fact the parcels are easier to convect than
during the day!!!!
Instability increases during the night

27. 20 June: 3 am Sounding
Dramatic moisture increase

28. 2 June Bore/Wave Event

29. BORE
Example
From
MAPR
4 June
Pre-bore height
Post height

30. 12 June Bore/Wave Event

31. 13 June Bore/Wave Event

32. 21 June Bore/Wave Event

33. 25 June Bore/Wave Event

34. Bore Height Displacements
Scattering
Layer
Height
(km)
Reference slope of .5 m/s
Reference slope of .5 m/s
Time (mins)

35. Bore Summary
Bore/wave disturbances are ubiquitous over this region at night when convection is present. ~26 event. Most events occur at the end of LLJ moisture return periods (when convection is present)
These disturbances can promote intense lifting with net displacements of up to ~1-2 km. They creating a deeper moist inflow and favorably impact stability. Some CI occurs. Peak vertical motions are >1-2 m/s.
Surface radars undercount bore/wave events (at a fixed location), since the lifting can be limited to heights above the PBL. Thus, ~26 events is likely an undercount!
These disturbances are (almost) always initiated by convection (slight evidence for both a secondary evening and larger nocturnal initiation). Later in the program and initiation is not by dry fronts.
Typical spacings of waves ~10-14 km, surface evidence (pressure disturbances (.25 – 1.5 hpa) with some closed circulations, typical duration is ~3-6 hrs with mesoscale to synoptic coverage areas.

36. 3rd Research Example: more rawinsonde controversy

37. SUCCESS (?) Significant impact on current conferences
23 papers at the recent Int’l Conference on Radar Meteorology (August in Seattle)
~20 papers at this meeting
Already see points where we will likely impact operational prediction in US (sonde transition work
and radar refractivity)
Already see strong research on the atmosphere and instrument techniques, but assimilation work for NWP is yet to come