GardeGarde Designing unified convection parameterizations: two proposals related to equation sets...

GardeGardeGardeGardeDesigning unified convection parameterizations: two Designing unified convection parameterizations: two proposals related to equation sets and entrainment. proposals related to equation sets and entrainment. Jean-Marcel Piriou, Météo-France.Jean-Marcel Piriou, Météo-France.GCSS / RICO Workshop, New-York 18-21 September 2006.GCSS / RICO Workshop, New-York 18-21 September 2006.

Designing unified convection parameterizations: two Designing unified convection parameterizations: two proposals related to equation sets and entrainment. proposals related to equation sets and entrainment. Jean-Marcel Piriou, Météo-France.Jean-Marcel Piriou, Météo-France.GCSS / RICO Workshop, New-York 18-21 September 2006.GCSS / RICO Workshop, New-York 18-21 September 2006.

Introduction: motivation for designing unified convective schemesIntroduction: motivation for designing unified convective schemes

Several operational and research models operatedSeveral operational and research models operated

Introduction: motivation for designing unified convective schemesIntroduction: motivation for designing unified convective schemes

Several operational and research models operatedSeveral operational and research models operated

Global regular ARPEGE / 4DVAR-ass. / 56 km

Global ARPEGEAquaplanet mode

PHYSICS

SCM ARPEGE (EUROCS, GATE, TOGA,BOMEX, ARM, RICO, …)

CSRM AROME / 3DVAR / 2.5 km

LAM ALADIN / 3DVAR / 10 km

Global stretched ARPEGE / 4DVAR-ass. / 23 to 133 km

Introduction: motivation for designing unified convective schemesIntroduction: motivation for designing unified convective schemesIntroduction: motivation for designing unified convective schemesIntroduction: motivation for designing unified convective schemes

Sharing parameterizations between Sharing parameterizations between models:models:

1.1. Simpler to manage a single set of Simpler to manage a single set of source codes.source codes.

2.2. Feedback from cases studies, Feedback from cases studies, scores, users scores, users modifications modifications improve also the other models.improve also the other models.

3.3. Sharing a simple and general Sharing a simple and general concept concept better understanding of better understanding of convection.convection.

SummarySummarySummarySummary

2 examples of on-going efforts in designing 2 examples of on-going efforts in designing unified convective parameterizations:unified convective parameterizations:

1.1. Separating microphysics and transport in Separating microphysics and transport in grid-scale equations. grid-scale equations. Fit wider range of Fit wider range of grid sizes (GCM - LAM - CSRM).grid sizes (GCM - LAM - CSRM).

2.2. Link between cold pools and Link between cold pools and entrainment. entrainment. Fit a wider range of Fit a wider range of processes (shallow NP – shallow P - deep processes (shallow NP – shallow P - deep conv.).conv.). A contribution for RICO A contribution for RICO observations and LES simulations?observations and LES simulations?

• Conclusions.Conclusions.

FinFinFinFin

Part 1: A convective scheme using Part 1: A convective scheme using separate microphysics and separate microphysics and transport terms in grid-scale transport terms in grid-scale equationsequations

MTCS (Microphysics and Transport Convective Scheme)MTCS (Microphysics and Transport Convective Scheme)

Separating microphysics and transport in grid-scale convective Separating microphysics and transport in grid-scale convective

equationsequations


Separating microphysics and transport in grid-scale convective Separating microphysics and transport in grid-scale convective

equationsequations

(Q1c: réchauffement convectif, Q2c: assèchement convectif fois L)(Q1c: réchauffement convectif, Q2c: assèchement convectif fois L)

Net condensationNet condensation

TransportTransport

MTCS:

Unbuoyant convective condens. (overs.)Unbuoyant convective condens. (overs.)

Cloudy evaporation Cloudy evaporation

Precipitation evaporation Precipitation evaporation

TransportTransport

SH précip., melt. SH précip., melt.

Buoyant convective condensationBuoyant convective condensation

MT-CSM & T coupled:


Mass flux / vertical velocity in the SGS convectif updraftMass flux / vertical velocity in the SGS convectif updraft


Mass flux / vertical velocity in the SGS convectif updraftMass flux / vertical velocity in the SGS convectif updraft

Taking into account the overshoots.Taking into account the overshoots.

LNB

Vertical integral of buoyancy

Top

P & NH effects Siebesma et al. (2003)

MTCS:MTCS:

MTCS (Microphysics and Transport Convective Scheme)MTCS (Microphysics and Transport Convective Scheme)MTCS (Microphysics and Transport Convective Scheme)MTCS (Microphysics and Transport Convective Scheme)

MTCS:

Consequences:Consequences:

• Grid-scale equations of the SGS convective Grid-scale equations of the SGS convective scheme are closer to those of CSRM or LES.scheme are closer to those of CSRM or LES.

• Can share microphysical modules between CSRM Can share microphysical modules between CSRM and parameterization (not done so far).and parameterization (not done so far).

• Validation of the parameterization versus CSRM or Validation of the parameterization versus CSRM or LES can be done for each of the above terms.LES can be done for each of the above terms.

• No need to assume a stationnarized cloud budget No need to assume a stationnarized cloud budget more consistent with a future prognostic more consistent with a future prognostic equation of cloud fraction.equation of cloud fraction.


What has been done so farWhat has been done so far


What has been done so farWhat has been done so far

MTCS:

First prototype withFirst prototype with

• Deliberately crude microphysics (simple Deliberately crude microphysics (simple condensation scheme, autoconversion/collection, condensation scheme, autoconversion/collection, diagnostic q_r q_s, Kessler-type evaporation)diagnostic q_r q_s, Kessler-type evaporation)

• New proposal for entrainment…New proposal for entrainment…

FinFinFinFin

Part 2: Cold pools and entrainmentPart 2: Cold pools and entrainment

Cold pools and entrainmentCold pools and entrainment

Context: EUROCS/GCSS diurnal cycle of deep convection over landContext: EUROCS/GCSS diurnal cycle of deep convection over land



ARPEGEARPEGEV1 V1

Q1 CSRM Q1 CSRM MNHMNH

ARPEGEARPEGEV1 + V1 +

entrentr. .

historiquehistorique

Q1 (K/day): apparent heat sourceQ1 (K/day): apparent heat source

local solar timelocal solar time local solar timelocal solar time

Q1 ARPEGEQ1 ARPEGEoper oper





Q2 Q2 ARPARPEGEEGE

oper oper

ARPEGEARPEGEV1 V1


ARPEGEARPEGEV1 + V1 +

entrentr. .

historiquehistorique

Q2 (K/day): apparent moisture sinkQ2 (K/day): apparent moisture sink

local solar timelocal solar time local solar timelocal solar time


A schematic view from CSRM animationsA schematic view from CSRM animations


A schematic view from CSRM animationsA schematic view from CSRM animations

Shallow cumulus phase

High entrainment: 1310 m

Cold pools and entrainmentCold pools and entrainmentCold pools and entrainmentCold pools and entrainment

Precipitating cumulus phase

Intermediate entrainment: 14106 m

Cold pools and entrainmentCold pools and entrainmentCold pools and entrainmentCold pools and entrainment

Deep convection phase

Low entrainment: 14103 m


Entrainment: an heuristic proposal: prognostic link evap. prec. Entrainment: an heuristic proposal: prognostic link evap. prec.

entr.entr.


Entrainment: an heuristic proposal: prognostic link evap. prec. Entrainment: an heuristic proposal: prognostic link evap. prec.

entr.entr.

Zeta’s source is precipitation evaporation, Zeta’s source is precipitation evaporation, zeta’s sink is a linear relaxation to zero.zeta’s sink is a linear relaxation to zero.

Entrainment epsilon depends on local pressure Entrainment epsilon depends on local pressure and on zeta, probability of undiluted and on zeta, probability of undiluted ascents at the current levelascents at the current level

14103 m 1310 m


Results on the EUROCS diurnal cycle of deep conv. over landResults on the EUROCS diurnal cycle of deep conv. over land



Q1 Q1 ARPARPEGEEGE

oper oper

ARPEGEARPEGEV1 V1


Q1Q1ARPEGEARPEGEhistoricalhistoricalentr.entr.





Q2Q2ARPEGARPEG

EEoper oper

ARPEGEARPEGEV1 V1


Q2Q2ARPEGEARPEGEhistoricalhistoricalentr.entr.





ARPEGEARPEGEV1 V1

• The new approach, a scheme based on The new approach, a scheme based on separate microphysics and transport separate microphysics and transport scheme, works: GATE, TOGA-COARE, scheme, works: GATE, TOGA-COARE, EUROCS sensitivity to humidity, EUROCS EUROCS sensitivity to humidity, EUROCS diurnal cycle of deep convection over diurnal cycle of deep convection over land. land.

• Relating prognostically the entrainment to Relating prognostically the entrainment to precipitation evaporation improves precipitation evaporation improves dramatically the predicted diurnal cycle of dramatically the predicted diurnal cycle of convection. (1D, 3D under progress).convection. (1D, 3D under progress).

• It also allows to use the same convective It also allows to use the same convective scheme for shallow and deep convection.scheme for shallow and deep convection.

• Piriou et al. 2006, submitted to JAS.Piriou et al. 2006, submitted to JAS.

Image: source Larry Di Girolamo, GCSS Workshop New-York, 2006

Larry Di Girolamo, about RICO:

1. « Lines along cold pools: 90% of the time. »

2. « Precipitation is strongly tied to mesoscale organization, especially along cold pools. »

3. « Clouds between ~ 3 to 4 km contribute the most to the total rain rates. »

Transition from shallow NP shallow P congestus deep: a collective effect of several drafts.

Studying this collective effect cannot be done through local PDFs nor global PDFs a new way of investigating RICO observations and LES simulations required?

FinFinFinFin

ConclusionsConclusions

ConclusionsConclusionsConclusionsConclusions

• MTCS proposal: separating Microphysics MTCS proposal: separating Microphysics and Transport in Convective Schemes.and Transport in Convective Schemes.

• Varying entrainment rates, depending on Varying entrainment rates, depending on cold pools dynamics. May be cold pools dynamics. May be parameterized in a quantitative and parameterized in a quantitative and energy conserving form.energy conserving form.

• Piriou et al. 2006, submitted to JAS.Piriou et al. 2006, submitted to JAS.

• GCSS / RICO: making studies GCSS / RICO: making studies (observations, LES simulations) to quantify (observations, LES simulations) to quantify convective transition as a collective effect convective transition as a collective effect of several clouds, through cold pools?of several clouds, through cold pools?

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GardeGarde Designing unified convection parameterizations: two proposals related to equation sets...

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