1. WGNE activities and plans
Andy Brown
© Crown copyright Met Office

2. Role of WGNE Working Group on Numerical Experimentation
Jointly established by the WCRP and the WMO Commission for Atmospheric Sciences (CAS)
Responsibility of fostering the development of atmospheric circulation models for use in weather prediction and climate studies on all time scales and diagnosing and resolving shortcomings.
A distillation of the Terms of Reference…..
Advice, liaison
Co-ordinated experiments
Workshops, publications, meetings
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3. Co-ordinated experiments and projects
© Crown copyright Met Office

4. Transpose-AMIP GOOD PROGRESS Cloudy-radiance DONE
Grey-zone GOOD PROGRESS
Verification
NWP performance (eg TCs, precipitation) ONGOING
Polar (CBS-style; ConcordIASI intercomparsion) NEW
Climate metrics GOOD PROGRESS
Issues with verification against own analysis NEW
MJO / Boreal Summer Intraseasonal Oscillation intercomparisons (with MJO-TF) ONGOING
Importance of aerosols for weather and climate Discussion WGNE 2012
Quality of monsoon simulations for weather and climate Discussion WGNE 2012
Comparison of model momentum budgets NEW
© Crown copyright Met Office

5. Transpose-AMIP: testing climate models in NWP mode
Core experiment is to run 64 hindcasts, each 5 days long, initialised from ECMWF YOTC analysis.
Optional experiment to repeat the same set of hindcasts with NASA MERRA re-analysis or own analysis.
The hindcasts spread through the annual and diurnal cycles and chosen to tie in with YOTC and coincide with some of the IOPs in:
VOCALS (SE Pacific stratocumulus)
AMY (Asian monsoon)
T-PARC (mid-latitude Pacific)
9 centres committed to submit data
MIROC5, HADGEM2, CNRM-CM5 now available to download
Data being used (e.g. papers for AR5)
© Crown copyright Met Office

6. Commonality of errors cross time and space scales: example of missing mid-level cloud
Climate model versus ISCCP
Mesoscale NWP versus CloudNet
Williams et al
Illingworth et al.
© Crown copyright Met Office

7. Time evolution of coupled model Sea surface temperature errors
© Crown copyright Met Office 7

8. Effect of coupled ocean on NWP
500hPa Height DJF hPa T JJA
BIAS
Two examples of good coupled skill relative to atmosphere-only control forecasts
Tropics is the main area of atmospheric performance difference
Performance mostly comparable in the extra-tropics
The tropics is where the main differences exist between the atmospheric performance of coupled and atmosphere control forecasts. This slide illustrates two examples : 500 hPa height in DJF and 925hPa T.
Other tropical variables where benefit is evident – relative humidity, geopotential height, wind speed.
Performance is mostly comparable in the extra-tropics but there are some areas where the coupled model does well
eg wind speed biases are reduced in the southern hemisphere.
RMSE
© Crown copyright Met Office
© Crown copyright Met Office D D 8

9. Diagnosing Asian Monsoon Errors
MO “dry” monsoon and EC “wet” monsoons develop within a few forecast days
EC model boundary layer over Arabian Sea implicated in monsoon problem
Which process is at fault?
Is it really a model problem?
How well do we know the ‘truth’?
Phase
Compare UKMO and ECMWF analyses and FC (July 2009) – Done
Compare forecasts and analyses from other OP NWP centres – TIGGE archive.
Phase 2 – MO & EC Lead –
Compare physical tendencies from short-range forecasts.
Compare analysis increments from DA systems.
Phase 3 – Extend Phase 2 to other OP NWP centres.
Encourage you to not be constrained by prediction timescales.- use appropriate prediction timescale to answer science questions.
Feedback, issues on anything
E-S what level of complexity is required at what timescale.

10. Mean monsoon precipitation and errors in July
mmday-1
Observed 20
Wet Monsoon
Problem spans all systems and timescales 15 10 7 5 3 2 1
ERA-Interim
D+5 T399
D+12–18 T399 20 10 5 2 -2 -5
-10
-20
Coupled T159
Uncoupled T159
Uncoupled T2047
GPCP mean precipitation and anomalies from it. ERA Interim based on 12 hr forecasts using cycle 31R2. Lead-times of 5 and days based on hindcasts (5 members once a week) using cycle 35R2 with persisted SST to day 10. Coupled results based on start-date 1 May using cycle 36R1. Uncoupled T159/T2047 -start- 1 November.

11. Dry Monsoon A Seamless Monsoon Precipitation & Low Level Flow Errors
Presented at THORPEX PDP meeting in July 2010
© Crown copyright Met Office

12. Daisuke Hotta, JMA

13. Effects of modelled processes on wind and humidity
Dynamics
Vertical diffusion
Convective
precipitation
Stratiform
precipitation
10ms-1day-1
-20
-12 -4 4 12 20
-20
-12 -4 4 12 20
-10 -6 -2 2 6 10
-10 -6 -2 2 6 10
2ms-1day-1
Unit = 0.1 gkg-1day-1
Understanding the lack of balance between processes (‘spin-up’). A new approach to diagnosis
Sum
(≈ Increment)
Mean July hPa model process tendencies over lead-times 1-13 hrs of 0 & 12 UTC forecasts. Bold: 5% significance

14. High resolution monsoon simulations

15. EMBRACE – 24 hr mean heating increments and mass flux for 17/6/11
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16. Workshops and meetings
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17. GOV/WGNE Ocean coupling workshop
Washington, USA. 19th-22nd March 2013
Follow on to ECMWF (2008) and Met Office (2009) workshops
Focus on coupled modelling for short and medium range
Use of short-range coupled to understand issues for longer range (e.g. subseasonal-seasonal)
© Crown copyright Met Office

18. 4th WGNE Workshop on Systematic Errors in Weather and Climate Models
Met Office, Exeter, UK. 15th- 19th April 2013
Weather and climate
Nature and causes of errors
Use of diagnostic techniques, observations, process models and simplified experiments to understand errors
© Crown copyright Met Office

19. Future directions
Continue to look cross-timescale – weather and climate (and air quality/chemistry) communities together
Need to keep championing the importance of model development
Maintain strong links to many other groups and projects e.g. WWRP, DOAS, GASS, polar, subseasonal-seasonal, WGCM……
Continuing distinction between
what can be done with large generic databases (predictability studies, verification, multi-model products etc)
what needs more focussed studies and comparisons (understanding differences and pros and cons of different approaches, model development etc)
© Crown copyright Met Office

20. Questions?
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21. Project sessions this week…
Stable boundary layers
The diagnosis of cloud and radiation processes in models
Weak temperature gradient
Grey-zone project
Microphysics modelling (KiD)
LoCo/SGP Testbed (GLASS project)
Marine Boundary Layer Cloud Feedbacks (CGILS)
Land-Atmosphere Interactions (GLASS/GABLS joint project)
Radiative Processes in Observations and Models
Cirrus
Tropical Convection observed during CINDY/DYNAMO
Polar Clouds (ISDAC)
Stratocumulus-to-trade cumulus transition
Vertical structure and diabatic heating of the MJO