QESM: The QUEST Earth System Model

1. QESM: The QUEST Earth System Model @Reading: Manoj Joshi, Jonathan Gregory, Allan Spessa, Annette Osprey @CEH Wallingford: Eleanor Blyth, Doug Clark @UEA: Erik Buitenhuis, Corinne Le Quéré @Leeds: Ken Carslaw, Graham Mann @Cambridge: Luke Abraham, Olaf Morgenstern, John Pyle @Lancaster: Oliver Wild and many others...

2. QESM: the QUEST Earth System Model • An unprecedented attempt to simulate the direction and strength of a wide range of biogeochemical processes and feedbacks affecting the functioning of the Earth system under contemporary and likely future climate scenarios. • Coordinated and managed by the NCAS-Climate and the Walker Institute. Its development builds upon the efforts of several exisiting modelling consortia currently engaged in the development of the climatic and biogeochemical models • http://www.quest-esm.ac.uk/

3. Climate models have historically been comprised of the following components: atmospheric dynamics/physics ocean dynamics/physics sea-ice land surface processes Atmospheric chemistry & aerosols mostly offline as climatologies Atmospheric physics & dynamics Ocean biology Ocean and sea-ice Land processes

4. Earth system models are comprised of the following components: atmospheric dynamics/physics ocean dynamics/physics sea-ice ocean biology atmospheric chemistry land surface processes dynamic terrestrial vegetation Atmospheric chemistry & aerosols Atmospheric physics & dynamics Ocean biology Ocean biology Dynamic vegetation Ocean and sea-ice Land processes

5. QUESM will be comprised of the following components: HadGEM3-A NEMO (Nucleus for European Modelling of the Ocean) CICE (Community Ice CodE) QPFT UKCA JULES (Joint UK Land Environment Simulator) ED (Ecosystem Dynamics)

6. Planned and ongoing work on QESM • The QESM is being developed in parallel with the Met Office Hadley Centre’s HadGEM3 model (an updated version of HadGEM1/1a) • There is a close relationship in timetable and components • HadGEM3-A (the atmosphere component of HadGEM3) will be run at N96 or above; QESM atmosphere is planned to run at N48 • HadGEM3-AO will (probably) have an ocean resolution of 1°, while QESM will run at 2° • The coarser resolution enables greater flexibility, such as running with 60 atmospheric layers in the vertical, and running it on systems such as the QUEST cluster

7. QESM progress so far • Three major changes have been tested in the N48 atmospheric model since the freezing of HadGEM2-OA in early 2007 • a parameterisation of surface-atmosphere exchange at coastal points (this is still under development) • implementation of adaptive detrainment on shallow convection • changes to the convective cloud/precipitation scheme when the cloud depth is small (<3 km) (also under development)

8. QESM progress so far • A parameterisation of surface-atmosphere exchange at coastal points (this is still under development) • This is an attempt to solve the problem of land drag dominating the momentum budget at coastal points, lowering windspeed, and lowering moisture exchange • The surface-lowest model layer windshear is tweaked upwards over the ocean fraction, and reduced over the land fraction • It's a bit ad-hoc, but it does dramatically improve moisture in the BL and rainfall over the Maritime continent (probably also by broadly representing sea breezes) • Its presence also fixes the AMOC drift in the N48 model, which is now ~17-18 Sv in the latest integration

9. QESM progress so far • A parameterisation of surface-atmosphere exchange at coastal points (this is still under development)

10. QESM progress so far • A parameterisation of surface-atmosphere exchange at coastal points (this is still under development) Reduced these tendencies

11. QESM progress so far • implementation of adaptive detrainment on shallow convection • changes to the convective cloud/precipitation scheme when the cloud depth is small (<3 km) • both of these improve the rainfall field, especially the monsoon

12. QESM progress so far • implementation of adaptive detrainment on shallow convection, changes to the convective cloud/precipitation scheme when the cloud depth is small: atmos-only results

13. QESM progress so far • In coupled mode, there are still problems, but the N48 AO model with the latest fixes displays performance that is comparable (ish) with HiGEM/HadGEM, e.g.: JJA rainfall

14. QESM progress so far • e.g.: NINO3 timeseries

15. QESM progress so far • e.g.: ENSO periodicity

16. QESM progress so far and future plans • Progress with the N48 model: • viable! (remember this wasn't the case earlier with the N48 model's "P minus E" problems) • N48 HadGEM2-A is 4.5x as quick as N96 HadGEM2-A • There are still ongoing issues similar to HadGEM/HiGEM • Future work: • We're soon moving from HadGEM2 to HadGEM3 • a different ocean means different coupled problems, so there's not much point in more tweaking

17. QESM progress so far and future plans • Progress with the N48 model: • viable! (remember this wasn't the case earlier with the N48 model's "P minus E" problems) • N48 HadGEM2-A is 4.5x as quick as N96 HadGEM2-A • There are still ongoing issues similar to HadGEM/HiGEM • Future work: • We're soon moving from HadGEM2 to HadGEM3 • a different ocean means different coupled problems, so there's not much point in more tweaking ...for the moment • Keeping in contact with the Met O's HadGEM3 development

18. QESM progress so far and implications for HiGEM • Perhaps the HadGEM3 implementation of the coastal mod can be tested in HiGEM- might have an effect on the Maritime Continent and the SW Pacific/Andes region (c.f: HadGEM1a/WAN) • Adaptive detrainment/entrainment has had beneficial effects on everything from the N48 model to the global NWP model; the river outflow scheme presently in HadGEM2 has had beneficial effects • The convective cloud changes would probably improve HiGEM performance • As for other coupled biases- sorry, not really my job anymore • but that doesn't mean I haven't got one or two ideas

19. Thank you for your attention