© Crown copyright Met Office Met Office progress report Andy Brown WGNE, Tokyo, October 2010.

© Crown copyright Met Office

Met Office progress reportAndy Brown

WGNE, Tokyo, October 2010


Outline

• Production systems

• Seasonal/climate

• Research issues

• Ocean-Atmosphere coupling

• Mid-level cloud

• Resolution and parametrization choices for convection-permitting models

• Scalability


Met Office production systems


DePreSys

TIGGE ensemble

GloSea4

MOGREPS-Rensemble

Coupled atmos/ocean

Earth System

Timescale36hrs 48hrs 5 days 15 days 6 months 10 years 30 years >100 years

1.5km

4km

12km

24km

40km

80km

150km

300km

Comple

xity

UKV

UK4 NAE

Global

HadCM3

HadGEM1

HadGEM2

Global atmosphere-only

Regional atmosphere-only

HadGEM3-RA regional HadGEM3

Atmospheric grid length


Operational NWP Models: Aug 2010

Global25km 70L4DVAR60h forecast twice/day144h forecast twice/day+24member EPS at 60km

NAE12km 70L4DVAR60h forecast 4 times per day +24member EPS at 18km

UKV1.5km 70L (variable resolution)

3DVAR36h forecast 4 times per day


Parallel Suite 22 : Nov 2009NEW UK 1.5km ModelNEW Seasonal Forecast Model based on HADGEM3Global NWP Model to 70 Levels (as HADGEM3)Ensemble NWP Model to 60km (Global) and 18km (regional)

Parallel Suite 23 : Mar 2010Regional and Ensemble NWP Models to 70 LevelsGlobal NWP Model to 25km

Parallel Suite 24 : Jul 2010NEW UK Air Quality Model with UKCA Chemistry PC2 cloud scheme to global NWP (as HADGEM3)Subgrid drainage shear parametrization to UK 1.5km model

Parallel Suite 25 : Nov 2010Global DA upgrades (N216; Covstats from EC ensemble)Seasonal forecast to L85 (troposphere as HADGEM3)

Key Model Upgrades 2009-10


Chief ScientistJulia Slingo

Director of Technology

Alan Dickinson

Deputy Director, Climate Science

& Head PartnershipsChris Gordon

Deputy Director, Foundation Science

Andy Brown

Deputy Director, Weather Science

Brian Golding

Science Management

Technology and IS

Observational based research

Parametrizations

Global model development

Dynamics research

Data assimilation

Satellite applications

Regional NWP

Ocean forecasting

Verification, Products, Applications

Understanding climate change

Monthly to decadal prediction

Earth system

Oceans

Impacts and adaptation


Ocean-atmosphere coupling


Coupled NWP research: Background

• International Workshop on Upper Ocean-Atmosphere Interactions on Weather and Climate Timescales held at the Met Office (Dec 2009):

• http://www.ncof.co.uk/Ocean-Atmosphere-Workshop-Dec-2009.html

http://www.ncof.co.uk/Ocean-Atmosphere-Workshop-Dec-2009.html


Coupled NWP research: Motivation

• Potential additional predictability/skill from representing air-sea physical coupling (MJO, diurnal cycle, TCs…)

• Quantify cost-benefit for NWP skill

• Tackle and improve coupled process errors at "source“ – leading to improvement of systematic errors and drifts in model predictions for longer timescales

• “Transpose-CMIP”

• Seamless prediction: more unified experimental design and model science from NWP through seasonal to climate prediction timescales

• Framework for developing and applying new coupled data assimilation techniques


Coupled NWP research: Status

1. Coupled configuration (currently running in early research mode):

• HadGEM3 N216L85 (A), ORCA 0.25L50 (O), CICE 0.25 (I)

• 3-hourly coupling (ocean vertical resolution permits diurnal mixed layer)

• Initialisation. A: Op. NWP analyses, O: FOAM analyses, I: Climatology

• Boundary conditions: Climatological surface/soil parameters, ozone; specified aerosol concentrations (model climatology)

• Atmosphere diagnostics: merger of seasonal-to-climate packages, allowing assessment of processes, variability and teleconnections, plus NWP packages allowing assessment of forecast verification and skill

• Ocean diagnostics: Operational FOAM packages, designed to output a comprehensive set of fields to validate the ocean surface and water column

2. Parallel atmosphere-only and ocean-only control experiments to allow the impact of coupling on the development of process-based errors to be isolated

• A: forced with OSTIA SSTs + persisted anomaly

• O: forced with 3-hourly mean fluxes from the atmosphere only model


Mid-level cloud


Missing midlevel cloud

Williams et alIllingworth et al.

ISCCP analysis Cloudnet

© Crown copyright Met Office km

Composite cyclones

Rainrate mm/day

km


Composite midlatitude cyclone

km

SW difference


CONSTRAIN: Cold air CONSTRAIN: Cold air outbreak 31 Jan 2010outbreak 31 Jan 2010


TOA SW from UKV and global

• Lack of mid-level cloud common to many models (NWP and climate)

• Some evidence for congestus and layer cloud issues

• Detailed studies with observations and high resolution models showing promise

UKV

global

CERES


Resolution and parametrization choices for convection-permitting models


Current operational regional models

Regional North Atlantic European (NAE) 12 km

MOGREPS-R regional ensemble 18 km -> 12 km

UK variable (UKV) resolution model 1.5 km

Future - Develop a 1.5 km ‘downscale’ ensemble system

Issues:

• Choice of 1.5 km small ensemble cf coarser resolution larger ensemble

• What to do with convection?

Convective-scale ensembles

Nigel Roberts


First case Hailstorm in Ottery

Dramatic thunderstorm

Very localised flash floods in

Otter Valley

Courtesy of Ken Mylne


MOGREPS output 00 UTC 30/10/08 T+18 - selected members

x x

w

950 hPa

Nigel Roberts

Different frontal structure and positioning in each MOGREPS-R (and hence UKV) member

Downscaling ensemble can add value


2.2 km compared to 1.5 km

Focus of convection is moved from coastal strip to over the sea

Nigel Roberts

Number of pixels exceeding the ‘extreme’ threshold 50mm in 6 hours from all 24 members

Limited testing supports choice of small 1.5km ensemble

xxx

Thanks to Changgui Wang


Convection closure

• 4km CAPE limited CAPE closure

• 1.5km No convection scheme

• Both models add significant value to coarser models (surface forcing; shower advection)

• Convection decisions based on case-studies / verification scores


12/10/00 flood event Peak rainfall rates within 60x60km squares over 12 hours 4km gridlength forecasts

10 20 30 40 50 60 70 80

mm/hour

No convection scheme With convection scheme CAPE dependent

Too high Too low Closer to

radar

10 20 30 40 50 60 70 80

mm/hour

10 20 30 40 50 60 70 80

mm/hour

Example of testing of existing 4km convection closure


Convection closure

• 4km CAPE limited CAPE closure

• 1.5km No convection scheme

• Both models add significant value to coarser models (surface forcing; shower advection)

• Convection decisions based on case-studies / verification scores

• Role for idealized work to supplement case study / verification work (metrics need care)?

• Relevance to global mid-level cloud issues?


Scalability


UM Scalability

0

2

4

6

8

10

12

14

0 500 1000 1500 2000

N512L70 - no I/O

N512L70 - full I/O

UKV

HadGEM3-AO

Cores

Spe

edup


Global Model Scalability Problems

• Most problems due to global lat-long grid

• ADI preconditioner for Helmholtz solver

• Advection communications and polar re-mapping

• Polar filtering

• Constant pole requirement

• ENDGAME dynamics expected to help

• Change to polar grid structure

• Ultimately expect to need to move away from lat-long

• I/O problems being addressed by I/O servers

© Crown copyright Met Office Met Office progress report Andy Brown WGNE, Tokyo, October 2010.

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Transcript of © Crown copyright Met Office Met Office progress report Andy Brown WGNE, Tokyo, October 2010.