Organized Convection in a New Era for Global Models

Pisharoty Distinguished Lecture - 2016Indian Meteorological Society, Pune ChapterInternational Institute for Tropical Meteorology

February 23, 2016

Mitchell W. MoncrieffClimate & Global Dynamics Laboratory

National Center for Atmospheric Research Boulder, CO 30305, USA

Weather Climate

Subseasonal-to-Seasonal

Underlying Chaotic Order, Multiscale Coherent Structures in a Turbulent Environment

Affects: Distribution, Intensity and Type of precipitation; Diabatic Heating;

Transport of Momentum; Cascade of Kinetic Energy

Formidable Parameterization Challenge

Organized Convection

Large-scale Organizatione.g., MJO, Monsoons

O (10,000 km)

Mesoscale Organizatione.g., MCSO (100 km)

Towards

Mesoscale - PermittingClimate Models

Two Interacting Worlds of Convective Organization

ExtratropicsQuasi-horizontal large-scale slope convection

controlled by potential vorticity dynamics, with embedded mesoscale organization

Downscale Control

Tropics: Multiscale convective organization as anintegral part of the tropical circulation

Upscale Cascade

Total Column Water Courtesy: Chris Velden, U. Wisconsin/Madison

Courtesy: Dundee Satellite Receiving Station, Scotland

Mesoscale Convective Systems (MCS)

MCS provide over 1/2 total tropical rainfall Long-lasting & propagating, MCS affects entire regions

Organized momentum transport is the antithesis of turbulent mixing Top-heavy convective - stratiform heating is an important characteristic

BUT MCS ARE MISSING FROM TRADITIONAL O(100 km)-grid CLIMATE MODELS

- Cumulus parameterizations fail to represent them

- Model resolution is too coarse to simulate them

New Era: Mesoscale-Permitting Global Models

Physical resolution of a numerical model is 5-10 times coarser than the computational grid:

O (100 km) grid: traditional convective parameterization

O (10 km) grid: mesoscale organization permitted, cumulus parameterized

O (1 km) grid: mesoscale organization resolved, cumulus permitted

O (100 m) grid: cumulus parameterization redundant

10-km grid is the mesoscale-permitting threshold for global models requiring a paradigm shift in thinking for organized convection parameterization

Fraction of Rain from MCS (TRMM satellite)

Tao & Moncrieff (2009)

Organized Convection Parameterization:

Coherent Multiscale Structure in a Turbulent Environment

Coherent Structure Paradigm

Scale-Selection Principles

Topics

1. Orogenic Mesoscale Convective Systems (MCS)

2. Madden-Julian Oscillation (MJO)

3. Dynamically Based Coherent Structure Parameterization

1. Virtual Global Field Campaigns

Topic 1: Orogenic MCS

Laing & Fritsch (1997)

Continental US

Tropical Africa

Propagating MCSs Modulate the Diurnal Cycle

+Afternoon

Next morning

~1000 km

Elevated heating sets

start position of MCS

Mesoscaledescent

MCS Family of cumulonimbus

Vertical shear

Organizes mesoscale circulationsand system propagation

C ~ 10 m/s

MCS: Resolution Dependence & Observational Validation

3-km explicitNEXRAD analysisCarbone et al. (2002) 10-km Betts-Miller10-km explicit

Moncrieff and Liu (2006)

Parameterized vs. Expicit Precipitation

Parameterized ExplicitTotal

Resolution Dependence of Convective Heating

30 km

10 km

3 km

Dynamical Structure

=10 km =30 km =3 km

3-km & 10-km grids realistic & similar

30-km grid unrealistic

a) Flow organization & cloud structure

b) Flow vectors & zonal component of velocity

Super-parameterized Community Atmospheric Model (SP-CAM3.5)

Standard CAM: No MCS

SPCAM: MCS heating simulated bymultiple CRM grids is communicated to the climate grid and organized by the large-scale vertical shear

Pritchard, Moncrieff, Somerville (2011)

Super-Parameterized Community Atmospheric Model (SP-CAM3)

Pritchard, Moncrieff & Somerville (2011)

Standard CAM: No MCS, no propagation

SP-CAM3: MCS-like organization, propagation

Regional-Refined Community Model (RRCM)

Courtesy, Julio Bacmeister, NCAR

Convective Organization in RRCM (6-km grid)

Courtesy, Julio Bacmeister, NCAR

Is the CMIP5 Warm Surface Temperature Bias over U.S. Continent a Propagating Convection Issue?

Ma et al. (2014)

Topic 2: Madden-Julian Oscillation (MJO)

Multiscale Coherent Structures in the MJO

Nakazawa (1988)

EastwardPropagating

CloudEnvelopes

MJOs(A, B,C,D)

WestwardPropagating

Meso-synopticFeatures

(C)

AB

CD

Courtesy: Marat Khairoutdinov

Superparameterized MJO

Courtesy: Marat Khairoutdinov

2-D CRMs in climate models simulate MCS, periodic boundary conditions trap them in CRM domains

MCSs can be generated on, and propagate across, the climate grid but are under-resolved and biased, e.g., mesoscale downdrafts distorted or missing

Super-parameterization in a 10 km-grid (mesoscale permitting) GCM would alleviate this bias, but be excessively expensive to run.

ECMWF Integrated Forecast System (IFS)

Moncrieff et al. (2012)

Global cloud-system resolving models

The NICAM Team

MJO and MCS Interaction in 7km-grid Global CRM (NICAM)

Miyakawa et al. (2012)

Mesoscale Momentum Transport: Average of 13,000 samples

Miyakawa et al. (2012)

Organized Convective Momentum Transport and Upscale Kinetic Energy Cascade

( )........... m mconvection

u uu wt z t

+ = =

Topic 3: Dynamically Based Coherent Structure Parameterization

a) Multi-cloud Model (Khouider & Majda, 2006)

b) Slantwise Layer Overturning Model (Moncrieff 2010)

Coherent Structure Paradigm forOrganized Convection Parameterization

O (10 km) Computational Grid Global Weather Models

Experimental Climate ModelsOrganized Convection

Parameterization

O (1 km) GridCloud-System

Resolving Models(CSRM)

MultiscaleTropical

Convection

Monsoons

IntraseasonalVariability

InterTropicalConvergence

Zone

Atmospheric Water Cycle

Dynamical Analogs

CoherentStructureParadigm

O (100 km) Computational Grid

Traditional Climate Models

Cumulus Parameterization

Organized Convection

ParameterizationPhysical & Dynamical

Processes

Multi-cloud Model & Slantwise Layer Overturning

P: Deep convection (1st baroclinic)

Hs: Upper-tropospheric stratiform region & evaporatively driven mesoscale downdrafts (2nd baroclinic)

Hc: Lower-tropospheric cumulus congestus & upper-tropospheric radiative cooling (2nd baroclinic)

Khouider & Majda (2006)

a) Multi-cloud Model: 1st and 2nd Baroclinic Heating

Dynamically Passive Planetary Boundary-layer

Dynamically Active Troposphere

Multicloud Parameterization: MJO in an idealized GCM

Ajayamohan et al (2013)

b) Slantwise Layer Overturning Model

= +

0

2 ( )z

z

FG dz

( )0z

BaroclinicGeneration

Vorticity Shear

Steering level

Latent heating

Evaporative cooling

0U (z) - c

Environmental shear

2102 U

C

Slantwise Layer Overturning Parameterization Experiments (SLOPE)

Topic 4: Virtual Global Field Campaigns

Year of Tropical Convection (YOTC)

YOTC-ECMWF

Virtual Global FieldCampaign

May 2008 April 2010

yotc.ucar.edu

Moncrieff & Waliser (2012)

YOTC MJOs

La Ninaconditions

El Nino conditions

2008

2009

2010

Moncrieff et al. (2012)

YOTC MJO Task Force Three intercomparison projects:

20-year Climate Simulations (24 GCMs)20-day Hindcasts2-day Hindcasts

Jiang et al. (2015)

Conclusions

10-km grid is a threshold resolution for explicit rrepresentation of organized convection in GCMs target for next-generation GCMs

New approaches to organized convection parameterization for GCMs based on multiscale coherent structures in a turbulent environment:

i) Multi-cloud model (Khouider & Majda 2006) ii) Slantwise layer overturning model (Moncrieff 2010; Moncrieff &

Waliser 2015)

Future work:

- WCRP-WWRP Subseasonal-to-Seasonal Prediction (S2S) program- Years of Maritime Continent (YMC) from mid-2017 to mid-2019- 2nd Virtual Global Field Campaign, 10 km grid ECMWF IFS- Regional-Refined Global Models, e.g., U.S. Continent, Maritime Continent

References Ajayamohan, R.S., and Coauthors, 2013: Realistic initiation and dynamics of the Madden-Julian

oscillation in a coarse resolution aquaplanet GCM. Geophys. Res. Let., 40, doi:10.1002/2013GL058187.

Jiang, X., and Co authors, 2015: Vertical structure and physical processes of the Madden-Julian oscillation: Exploring key model physics in climate simulations. J. Geophys. Res, Atmos., 120, 4718-4748.

Khouider, B., and M.W. Moncrieff, 2015: Organized convection parameterization for the ITCZ. J. Atmos. Sci.,72,3073-3096, doi: http://dx.doi.org/10.1175/JAS-D-15-0006.1.

Ma, H-Y, and Coauthors , 2014: On the Correspondence between Mean Forecast Errors and Climate Errors in CMIP5 Models. J. Climate 27:4, 1781-1798. doi: http://dx.doi.org/10.1175/JCLI-D-12-00134.1

Miyakawa, T. ,and Coauthors, 2012: Convective momentum transport by rainbands within a Madden-Julian oscillation in a global nonhydrostatic model. J. Atmos. Sci., 69, 1317-1338, doi: 10.1175/JAS-D-11-024.1.

Moncrieff, M.W., 1992: Organized convective systems: Archetypal models, mass and momentum flux theory, and parameterization. Quart. J. Roy. Meteor. Soc., 118, 819-850.

Moncrieff, M. W., 2010: The multiscale organization of moist convection and the intersection of weather and climate. In Climate Dynamics: Why Does Climate Vary? Geophys. Monogr. Ser., Vol. 189, Eds. D-Z. Sun and F. Bryan, pp. 326, doi: 10.1029/2008GM000838.

Moncrieff, M.W., and Coauthors, 2012: Multiscale convective organization and the YOTC Virtual Global Field Campaign Bull. Amer. Meteorol. Soc., 93, 1171-1187, doi:10.1175/BAMS-D-11-00233.1

Moncrieff, M.W., and D.E. Waliser, 2015: Organized Convection and the YOTC Project., Seamless Prediction of the Earth-System: From Minutes to Months, (G. Brunet, S. Jones, P.M. Ruti Eds., WMO-No. 1156), ISBN 978-92-63-11156-2, Geneva.

Waliser, D.E., and Coauthors, 2012: The Year of Tropical Convection (May 2008 to April 2010): Climate variability and weather highlights. Bull. Amer. Meteorol. Soc., 93,1189-1218, doi:10.1175/2011BAMS3095.1

Thanks for your attention

Organized Convection in a New Era for Global Models Slide Number 2Slide Number 3Mesoscale Convective Systems (MCS)New Era: Mesoscale-Permitting Global ModelsFraction of Rain from MCS (TRMM satellite)Organized Convection Parameterization:Coherent Multiscale Structure in a Turbulent Environment Coherent Structure Paradigm Topics Topic 1: Orogenic MCS Propagating MCSs Modulate the Diurnal CycleMCS: Resolution Dependence & Observational ValidationParameterized vs. Expicit PrecipitationResolution Dependence of Convective HeatingDynamical StructureSuper-parameterized Community Atmospheric Model (SP-CAM3.5)Super-Parameterized Community Atmospheric Model (SP-CAM3)Regional-Refined Community Model (RRCM)Convective Organization in RRCM (6-km grid) Is the CMIP5 Warm Surface Temperature Bias over U.S. Continent a Propagating Convection Issue?Topic 2: Madden-Julian Oscillation (MJO) Multiscale Coherent Structures in the MJOSlide Number 24Slide Number 25Global cloud-system resolving models MJO and MCS Interaction in 7km-grid Global CRM (NICAM)Mesoscale Momentum Transport: Average of 13,000 samplesOrganized Convective Momentum Transport and Upscale Kinetic Energy Cascade Topic 3: Dynamically Based Coherent Structure Parameterization a) Multi-cloud Model (Khouider & Majda, 2006) b) Slantwise Layer Overturning Model (Moncrieff 2010)Coherent Structure Paradigm forOrganized Convection Parameterization Slide Number 32Multicloud Parameterization: MJO in an idealized GCM b) Slantwise Layer Overturning ModelSlantwise Layer Overturning Parameterization Experiments (SLOPE)Topic 4: Virtual Global Field CampaignsYear of Tropical Convection (YOTC) Slide Number 37Slide Number 38YOTC MJO Task Force ConclusionsReferences Thanks for your attention