7 th cops workshop collège doctoral européen strasbourg, france, 27 - 29 october 2008 beyond case...

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.

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

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)

June 20: IOP 4bJune 20: IOP 4b

UW-CIMSS Satellite based Nowcasting and Aviation Application Team, supported by NASA and NOAA (www.cops2007.de)

• 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

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

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

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

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

-35.00

-30.00

-25.00

-20.00

-15.00

-10.00

0.00 500.00 1000.00 1500.00 2000.00 2500.00 3000.00 3500.00 4000.00 4500.00

Cumulus condensation level

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

4) Results 2

-35.00

-30.00

-25.00

-20.00

-15.00

-10.00

0 0.2 0.4 0.6 0.8 1 1.2

CI nowhere:0, anywhere:1

Role of near surface air temperature and humidity

• 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

4) Results 3

0 0.5 1 1.5 2 2.5 3 3.5 4

CI no:0, 1 … 4 subregions

Role of CAPE

• 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

4) Results 4

Role of upper level forcing: differential vorticity advection (from GFS)

• 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)

0 0.2 0.4 0.6 0.8 1

CI no:0 anywhere:1

0 0.2 0.4 0.6 0.8 1 1.2

CI no:0 anywhere:1

0 0.2 0.4 0.6 0.8 1 1.2

CI no:0 anywhere:1

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

7 th cops workshop collège doctoral européen strasbourg, france, 27 - 29 october 2008 beyond case...

ci group

ci factors

cops period

cops data set

convection amf

case studies

cumulus convection

control regions ci indicators

Documents

listo cops

cops killing cops

rhyming cops

are cops constitutional

cops and collars

stigasoft metro cops

cops p296 pub

engagement center (second floor) · multi-racial unity...

cops p164 pub

aug. 11, 2011 cops

wrong cops fanzine

cops ,017 - moi

natomas cops log 08

cops in california

eumetsat contributions to cops

cops dhrdd1995.pdf

1 int. cops fachkreis int. cops expert group 10.02.2011

crooked cops

cops have hearts

magazine water cops