Transcript Overview of The International H2O Project (IHOP_2002)(Parsons)

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 (SHIS 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
• 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)
• Session 6
–
–
–
–
–
–
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)
RESEARCH HIGHLIGHTS
• 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)
• Session 7
– Schwemmer et al.
(HARLIE)
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
4πf
Target phase: Ф(r) = 2πf ttravel(r) = —— r n
c
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
10
5
0
7º
11º+
P3
Broad Td gradient; Hints of convergence
IHOP Examples: Dry-Line Genesis
Fine line appears
20:51
10
5
0
P3
Tight
gradient
moving
Tightening
gradient
IHOP Examples: Dry-Line Evolution
Dry line splits
…AsTo
dry
line
moves
west
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
CAPE vs. CIN
0
Unstable, capped env.
-100
CIN (J kg-1)
-200
Dramatic stabilization,
-300
-400
1730 pm
expected due to radiational cooling !
-500
0301 am
-600
Very stable
-700
-800
0
500
1000
1500
CAPE (J kg-1)
2000
2500
“Surface” and Inversion Parcels
CAPE vs. Convective Inhibition
0
0301 am
-100
CIN (J kg-1)
-200
-300
1730 pm
1730 pm
-400
-500
-600
0301 am
-700
Opposite trends
-800
0
500
1000
1500
2000
2500
CAPE (J kg-1)
In fact the parcels are easier to convect than
Instability increases during the night
during the day!!!!
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
4.5
•
Motivated by Belay Demoz’s excellent (yet unpublished case study)
4
3.5
3
Scattering
Layer
Height
(km)
Reference slope of .5 m/s
2.5
Reference slope of .5 m/s
2
1.5
1
0.5
0
0
5
10 15 20 25 30 35 40 45 50 60 65 75
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