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

GENERAL MOTIVATION

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)

Isentrophic Airflow and Sounding Domain Isentropic streamlines (37 C) for 2330 UTC 4 May 1961. The dashed lines are isobars at 100 hPa intervals (from Carlson and Ludlam 1968)

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

IHOP_2002

IHOP Aircraft

Convective Initiation Flight Plan

Mobile Mesonet, Smart-R radar and Control Center

Convective Initiation of a flash flood

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.

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)

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)

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.

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

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

IHOP Examples: Dry-Line Genesis 5 10 7º 11º+ P3 Broad Td gradient; Hints of convergence

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

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

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

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.

IHOP_2002 Sounding Western OK 1730 pm LST CAPE CIN

Water Vapor: 20 June

BORE Example From MAPR 4 June

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

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

20 June: 3 am Sounding Dramatic moisture increase

2 June Bore/Wave Event

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

12 June Bore/Wave Event

13 June Bore/Wave Event

21 June Bore/Wave Event

25 June Bore/Wave Event

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

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.

3rd Research Example: more rawinsonde controversy

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