1. Blocking in the ECMWF model: Sensitivity to resolution and model physics Antje Weisheimer Thomas Jung Tim Palmer

2. Blocking in the ECMWF model Reading University 15 Dec 2010 Outline 1.Resolution dependent blocking frequency The ATHENA project T159 vs T511 vs T1279 2.The roles of topography and the mean state of the flow T511 with low resolution topography Impact of the mean state/systematic error 3.Physical parameterisations and blocking Statistics of blocking in the IFS model from 2005-2009 Seasonal re-forecasts of the summer 2003 over Europe

3. Blocking in the ECMWF model Reading University 15 Dec 2010 Outline 1.Resolution dependent blocking frequency The ATHENA project T159 vs T511 vs T1279 2.The roles of topography and the mean state of the flow T511 with low resolution topography Impact of the mean state/systematic error 3.Physical parameterisations and blocking Statistics of blocking in the IFS model from 2005-2009 Seasonal re-forecasts of the summer 2003 over Europe

4. Blocking in the ECMWF model Reading University 15 Dec 2010 Project ATHENA: High Resolution Global Climate Simulations … to determine the feasibility of using high-end computing resources to simulate climate variability and global climate change and to test the benefit of employing very high resolutions for weather and climate models. NSF offered dedicated use of the NSF Cray XT-4 Athena supercomputer in Oak Ridge, Tennessee, from Oct 2009 -March 2010 international team of over 30 people from six institutions on three continents 900 TB of output, >90% level of utilization of the resource, general data availability in 2011 ECMWF: 13-month atmospheric climate integrations from 1960(1989)-2007 with IFS CY36R1 T159 (~120km) T511 (~ 40km) T1279 (~ 16km) [T2047 (~ 10km)]

5. Blocking in the ECMWF model Reading University 15 Dec 2010 Blocking frequency: T159 1960-2007 reanalysis T159 T511 T1279 T2047

6. Blocking in the ECMWF model Reading University 15 Dec 2010 Blocking frequency: T159 vs T511 1960-2007 reanalysis T159 T511 T1279 T2047

7. Blocking in the ECMWF model Reading University 15 Dec 2010 Blocking frequency: T159 vs T511 vs T1279 1960-2007 reanalysis T159 T511 T1279 T2047

8. Blocking in the ECMWF model Reading University 15 Dec 2010 Outline 1.Resolution dependent blocking frequency The ATHENA project T159 vs T511 vs T1279 2.The roles of topography and the mean state of the flow T511 with low resolution topography Impact of the mean state/systematic error 3.Physical parameterisations and blocking Statistics of blocking in the IFS model from 2005-2009 Seasonal re-forecasts of the summer 2003 over Europe

9. Blocking in the ECMWF model Reading University 15 Dec 2010 Blocking frequency: T511 with T159 topography 1980-2007 reanalysis T159 T511 T1279 T2047

10. Blocking in the ECMWF model Reading University 15 Dec 2010 Blocking frequency: T511 with T159 topography 1980-2007 reanalysis T159 T511 T511topoT159

11. Blocking in the ECMWF model Reading University 15 Dec 2010 T159 with T511 mean state 1980-2007 reanalysis T159 T511 T511topoT159 T159meanT511

12. Blocking in the ECMWF model Reading University 15 Dec 2010 1980-2007 reanalysis T159 T511 T511topoT159 T511 topoT159 meanT511 T511 topoT159 with T511 mean state

13. Blocking in the ECMWF model Reading University 15 Dec 2010 1980-2007 reanalysis T159 T511 T511topoT159 T511 topoT159 meanT159 T511 topoT159 with T159 mean state

14. INSTITUT CATALÀ DE CIÈNCIES DEL CLIMA Blocking frequency in seasonal forecasts Northern Hemisphere DJF blocking frequency for 1-month lead seasonal hindcasts for the ECMWF, Météofrance, Met Office, IfM and INGV forecast systems over the period 1981-2005 compared to ERA40/ERA-Int (black solid). Results are for the Tibaldi and Molteni index (reversal of the meridional gradient of Z500). 95% confidence intervals are shown. Standard indexSystematic error removed courtesy F. Doblas-Reyessee also Doblas-Reyes et al., JGR (2002)

15. Blocking in the ECMWF model Reading University 15 Dec 2010 Outline 1.Resolution dependent blocking frequency The ATHENA project T159 vs T511 vs T1279 2.The roles of topography and the mean state of the flow T511 with low resolution topography Impact of the mean state/systematic error 3.Physical parameterisations and blocking Statistics of blocking in the IFS model from 2005-2009 Seasonal re-forecasts of the summer 2003 over Europe

16. Blocking in the ECMWF model Reading University 15 Dec 2010 Major changes to the IFS model from 2005 to 2009 modeldate ofmodifications cycleintroduction CY29R2Jun 2005 CY30R1Feb 2006vertical resolution L60  L91 CY31R1Sep 2006turbulent orographic form drag scheme System 3 for operational seasonal forecasting (T159L60) CY32R2Jun 2007new radiation scheme (SW, cloud radiation interaction, MODIS albedo), retuning of GWD CY32R3Nov 2007convection (entrainment and deep convection closure), vertical diffusion, new land-surface module H-TESSEL CY33R1Jun 2008retuning + bugfix

17. Blocking in the ECMWF model Reading University 15 Dec 2010 reanalysis CY33R1 CY32R3 CY29R2-32R2 1962-2005 primarily impact of convection scheme (and turbulent orographic form drag) Statistics of blocking in the IFS model from 2005-2009 Jung et al., QJ (2010)

18. Blocking in the ECMWF model Reading University 15 Dec 2010 The European heat wave of the summer 2003 T2m precip Z500 Seasonal retrospective forecasts initialised in May: The current operational System 3 (CY31R1) neutral wet neutral

19. Blocking in the ECMWF model Reading University 15 Dec 2010 T2m precip Z500 The European heat wave of the summer 2003 Seasonal retrospective forecasts initialised in May: CY33R1 very warm very dry positive

20. Blocking in the ECMWF model Reading University 15 Dec 2010 T2m precip Z500 The European heat wave of the summer 2003 Seasonal retrospective forecasts initialised in May: Impact of the land-surface scheme

21. Blocking in the ECMWF model Reading University 15 Dec 2010 Conclusions Blocking is model resolution dependent. improved blocking statistics for horizontal resolution increase from T159 (~120km) to T511 (~40km) future work will investigate blocking on different time scales (  M. Matsueda’s talk) Model topography needs to be resolved at a sufficiently high resolution. Reducing the systematic errors of the mean flow is important but not necessarily easier than getting blocking itself right. improved blocking for “low-res” (T159) simulations with “high-res” (T511) mean state Model representation of physical processes is essential too. recent changes to the convection parametrisation had major positive impact on blocking frequency critical role of land surface scheme on summer 2003 atmospheric circulation