7 th COPS Workshop Collège Doctoral Européen Strasbourg, France, 27 - 29 October 2008 Beyond case...
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Transcript of 7 th COPS Workshop Collège Doctoral Européen Strasbourg, France, 27 - 29 October 2008 Beyond case...
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7th COPS WorkshopCollège Doctoral Européen
Strasbourg, France, 27 - 29 October 2008
Beyond case studies: CI during COPS Ch. Kottmeier and CI group
Beyond case studies: mechanisms initiating convection during the COPS-Experiment
Christoph Kottmeier
Karlsruhe Institute of Technology
and the COPS CI-group
Christian BartlottKlaus Beheng Andreas BehrendtAlan Blyth Ulrich CorsmeierR. Coulter George Craig Galina Dick Thomas FokenPaolo Di Girolamo
Martin HagenChristian Hauck Norbert
KalthoffChristoph KiemleHelmut Mayer Stephen Mobbs Evelyne Richard Reinhold Steinacker Andreas WieserVolker Wulfmeyer Siegfried Vogtet al.
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7th COPS WorkshopCollège Doctoral Européen
Strasbourg, France, 27 - 29 October 2008
Beyond case studies: CI during COPS Ch. Kottmeier and CI group
Outline of talkDuring COPS, convection was initiated and developed much differently, depending on e.g. the instability of air masses, on the forcing from the surface and from the middle/upper troposphere. For improving QPF we need to understand the processes and predict convection not only on „golden days“ but generally for a wide range of synoptic situations.
Can we generally identify the responsible initiation mechanisms ?
What is their relative importance for CI?
Which is the added value of the full COPS data set?
Is there a useful statistical approach of understanding CI and its forcing mechanisms?
Cloud pictures during IOP 4b, 20/06/07 18 UTCnear Freudenstadt (Nordschwarzwald
Bilder: Marcus Engelhardt
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7th COPS WorkshopCollège Doctoral Européen
Strasbourg, France, 27 - 29 October 2008
Beyond case studies: CI during COPS Ch. Kottmeier and CI group
CI factors considered for the whole COPS period 01/06 -31/08:
1) Identify initiation of deep convection -> MSG nowcasting products
2) Are near surface humidity and temperature favourable for cumulus-convection? -> AMF data set
Is there potential instability of the atmosphere? -> AMF and DWD Stuttgart radiosondes
Factors inhibiting convection -> AMF and DWD Stuttgart radiosondes
3) Convection inhibiting/enhancing CI in the middle/upper troposphere (vorticity-, advection, mean vertical motion) -> GFS analysis (via www.wetter3.de team)
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7th COPS WorkshopCollège Doctoral Européen
Strasbourg, France, 27 - 29 October 2008
Beyond case studies: CI during COPS Ch. Kottmeier and CI group
June 20: IOP 4bJune 20: IOP 4b
1) Identify initiation of deep convection -> MSG nowcasting products
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7th COPS WorkshopCollège Doctoral Européen
Strasbourg, France, 27 - 29 October 2008
Beyond case studies: CI during COPS Ch. Kottmeier and CI group
1) Identify initiation of deep convection -> MSG nowcasting products
UW-CIMSS Satellite based Nowcasting and Aviation Application Team, supported by NASA and NOAA (www.cops2007.de)
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7th COPS WorkshopCollège Doctoral Européen
Strasbourg, France, 27 - 29 October 2008
Beyond case studies: CI during COPS Ch. Kottmeier and CI group
2) Identify initiation of deep convection -> MSG nowcasting products
• Locations of Convection Initiation
• 15 min resolution
• whole COPS period and region
• resampled to 3 periods/day: 6 UTC +- 3h, 12 UTC +- 3h,18 UTC +- 3h
• 4 control regions• CI indicators:- CI in 0, 1, 2, 3, 4 of the regions - CI nowhere (0) or in any (1) of the 4 regions
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7th COPS WorkshopCollège Doctoral Européen
Strasbourg, France, 27 - 29 October 2008
Beyond case studies: CI during COPS Ch. Kottmeier and CI group
CAPE: 704 J/kg
High moisture up to 650 hPa
approx. 29 C needed to initiate cumulus
Inversion layer
IOP 4b
High CAPE, Inversion at 820 hPa avoids CI from valleys
FZK Radio-sonde Burnhaupt, southern Vosges, 08 UTC
2)Atmospheric stability, Convection indices
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7th COPS WorkshopCollège Doctoral Européen
Strasbourg, France, 27 - 29 October 2008
Beyond case studies: CI during COPS Ch. Kottmeier and CI group
2)Atmospheric stability, Convection indices
Lifted Index
Mixed layer lifted Index
T0 – Ttrig
Mixed layer T0 – Ttrig
Surface based CIN
Mixed layer CIN
Surface based CAPE
Mixed layer CAPE
AMF: ARM mobile facility at Heselbach, Murg valley
Continuous operation, 3-hourly radiosondes, convection indices
DWD Stuttgart radiosonde Continuous operation, 12-hourly radio-
sondes, convection indices
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7th COPS WorkshopCollège Doctoral Européen
Strasbourg, France, 27 - 29 October 2008
Beyond case studies: CI during COPS Ch. Kottmeier and CI group
Quasigeostrophic Theory* ( replaced by g)
-> approx. vorticity equation and -equation
*Literature: "Synoptische Meteorologie" by Manfred Kurz. Leitfaden für die Ausbildung im Deutschen Wetterdienst. "Dynamik der Atmosphäre" by Helmut Pichler. Lehrbuch zur theoretischen Meteorologie.
Rising motion is forced in areas of
• Positive advection of absolute vorticity, increasing with height
• Relatively (to surroundings) largest warm air advection, weakest cold air advection
• Relatively strongest diabatic heating, relatively weakest diabatic cooling
Maps for COPS IOPs: http://www2.wetter3.de/
3) Middle and Upper tropospheric forcing
: vertical velocity in p-system : pressure : temperature : Coriolis parameter : geostrophic relative vorticity : diabatic heating : geostrophic wind vector : Coriolis parameter ref. latitiude : gas constant : specific heat at const. pressure : horizontal LaplaceOperator : isobaric gradient
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7th COPS WorkshopCollège Doctoral Européen
Strasbourg, France, 27 - 29 October 2008
Beyond case studies: CI during COPS Ch. Kottmeier and CI group
500 hPa geopotential -- MSL pressure -- rel. topography
Analyse12 UTC
IOP 4b3) Middle and Upper tropospheric forcing
Advection of abs. vorticity at 300 hPa
Analysis18 UTC
in hPa/h
Mean vertical velocity at 500 hPa
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7th COPS WorkshopCollège Doctoral Européen
Strasbourg, France, 27 - 29 October 2008
Beyond case studies: CI during COPS Ch. Kottmeier and CI group
-35.00
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
5.00
0.00 500.00 1000.00 1500.00 2000.00 2500.00 3000.00 3500.00 4000.00 4500.00
Cumulus condensation level
Su
rfac
e ai
r te
mp
- t
rig
ger
tem
p
4) Results 1
Role of near surface air temperature and humidity
• All days: 12 UTC +- 3h:
• Trigger temperature not reached, too cold and dry at sfc
• Trigger temperature almost reached in Murg valley, possibly reached over mountains or later that day
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7th COPS WorkshopCollège Doctoral Européen
Strasbourg, France, 27 - 29 October 2008
Beyond case studies: CI during COPS Ch. Kottmeier and CI group
4) Results 2
-35.00
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
5.00
0 0.2 0.4 0.6 0.8 1 1.2
CI nowhere:0, anywhere:1
Su
rfac
e ai
r te
mp
. - t
rig
ger
tem
p.
Role of near surface air temperature and humidity
• All days: 12 UTC +- 3h:
• CI happened in 1/3 of cases with Tsfca > Ttrig and CI was mostly suppressed for Tsfca > Ttrig
• CI also happened in 2/3 of cases with Tsfca < Ttrig; down to -13 K in Murg valley: important role of mountain and slope/mountain circulations; possibly air mass convection originating from upper levels
• Some cases of no CI although Tsfca > Ttrig in Murg valley;
too low CAPE, high CIN
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7th COPS WorkshopCollège Doctoral Européen
Strasbourg, France, 27 - 29 October 2008
Beyond case studies: CI during COPS Ch. Kottmeier and CI group
4) Results 3
-200
0
200
400
600
800
1000
1200
1400
1600
1800
0 0.5 1 1.5 2 2.5 3 3.5 4
CI no:0, 1 … 4 subregions
CA
PE
_CC
L
Role of CAPE
• All days: 12 UTC +- 3h:
• Isolated CI (CI=1) and widespread CI (CI=4) happened with relatively small CAPE
-> marginal CI conditions; airmass convection with upper level forcing?
• Some cases without CI and CAPE up to 700 J/kg -> Trigger temperature not reached
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7th COPS WorkshopCollège Doctoral Européen
Strasbourg, France, 27 - 29 October 2008
Beyond case studies: CI during COPS Ch. Kottmeier and CI group
4) Results 4
Role of upper level forcing: differential vorticity advection (from GFS)
• All days: 12 UTC +- 3h:
• Differential vorticity advection: no significant difference of for situations w/o CI
• Laplace of warm air advection: much larger variability and negative mean for situations with CI
• Omega(500 hPa): larger variability but no mean difference for situations with CI
• Problem: 1 deg resolution of GFS (0,5 deg for maps on www.cops2007.de)
-50
-40
-30
-20
-10
0
10
20
30
0 0.2 0.4 0.6 0.8 1
CI no:0 anywhere:1
Vo
rtic
ity
adve
ctio
n (
300
hP
a -
850
hP
a) 1
0E-
9s^
-2
-20
-15
-10
-5
0
5
10
15
20
0 0.2 0.4 0.6 0.8 1 1.2
CI no:0 anywhere:1
La
pla
ce
of
ad
ve
cti
on
of
rel.
To
p.
10
E-9
Km
^-2
s-1
-100
-80
-60
-40
-20
0
20
40
60
80
100
0 0.2 0.4 0.6 0.8 1 1.2
CI no:0 anywhere:1
Om
ega_
500h
Pa
in 1
0^2P
a/s
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7th COPS WorkshopCollège Doctoral Européen
Strasbourg, France, 27 - 29 October 2008
Beyond case studies: CI during COPS Ch. Kottmeier and CI group
4) Results
Summary:
• CI index from MSG is a useful benchmark for diagnosing CI, comparing CI-
relevant processes and CI model forecasts
• CAPE, CIN (from AMF and other radiosondes) and surface triggering factors are
consistently important as ingredients for CI over the whole COPS period.
• Information about surface heterogeneity (mountains, mesoscale circulation,
surface parameters and heating) and their model representation are indispensible
for CI
• The role of middle and upper tropospheric forcings are masked by the
insufficient resolution of GFS (1 deg) data.
• Needed for progress: mapped distributions of all relevant surface parameters,
middle/upper tropospheric forcing factors from higher resolution modelling