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HPC for better understanding of the tropical meteorology

Necessity of … . HPC for better understanding of the tropical meteorology . Y . Kajikawa and H. Tomita Oct 11 th , 2013, @GMCL, PNU . History of climate modeling (1). Richardson’s Dream (1910s-1920s). History of climate modeling (2).

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HPC for better understanding of the tropical meteorology

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  1. Necessity of … HPC for better understanding of the tropical meteorology Y. Kajikawa and H. Tomita Oct 11th, 2013, @GMCL, PNU

  2. History of climate modeling (1) Richardson’s Dream (1910s-1920s)

  3. History of climate modeling (2) ENIAC (Electronic Numerical Integrator And Computer) was the first electronic general-purpose computer. 1947-1955 @Maryland http://en.wikipedia.org/wiki/ENIAC

  4. [Q] Why does the climate model require the HPC? • 1. Increase of resolution • To know more detail structure! • e.g. horizontalResolutionin usual climate model : • 100km（2000）/ 20km (2005） • 3.5km on K-computer http://www.nies.go.jp/kanko/kankyogi/19/04-09.html

  5. [Q] Why does the climate model require the HPC? • 2. Increase of processes • To know more complex interactions. • Atm. Ocn. Lnd. models • Carbon cycle, aerosol, chemistry, dynamic vegetation process • External forcing • Variability of solar constant • CO2emission scenario • by IPCC run • -> Earth System model

  6. [Q] Why does the climate model require the HPC? • 3. Increase of ensembles • To make our results more reliable. • Statistical knowledge is necessary. http://www.jma.go.jp/jma/kishou/know/kisetsu_riyou/glossary/ensenble.html

  7. Importance of the cloud process (1) • 1. Engine for general circulation : • Cumulus has an important role for atmospheric heat transfer over the globe. (latitudinal direction). • 2. Hierarchical structure • generates many phenomena. • Cloud cluster , super cloud cluster, tropical cyclone, MJO, … 7

  8. Importance of the cloud process (2) • Large impact on the energy balance in climate: • Parasol effect : reduce the incoming solar incidence. • Green house effect : cloud emits infrared radiation into the surface and space. • Difficulty : the interaction with aerosol and chemistry through radiation process • Indirect effect of aerosol : optical thickness of cloud and cloud life time. • Direct effect of aerosol is also important. Parasol effect Reflection of solar incident Greenhouse effect Emission of infrared 8

  9. Various cloud types exist in our earth! cumulus Shallow cloud cirrus …Very difficult to model the cloud! 9

  10. Hierarchical structure of clouds Super cloud cluster～ 1000km MJO Cloud element: cumulus Cloud cluster～ 100km 10km １km 10km Earth diameter :12740km

  11. understanding of cloud dynamics Example of cloud origination meso-scale cloud Cloud drop aggregation Fall as precipitation Cooling by evaporation Generation of new clouds Generation of new clouds Cold pool 11

  12. Cloud has many features and large impact on the climate throughthe complicated processes. • What should we start to study the cloud processes by modeling in the age of HPC?

  13. Expression of the clouds 10 years ago • Cumulus: • Each of cumuli cannot be expressed directly due to too coarse grid • The effect of cumulus is taken a count as parameterization Uncertainty ： many methods generate many results! Each of clouds < 10 km Grid intervals：100 km

  14. New Approach from 2004 • Cumulus (cloud-system ) can be resolved! • To avoid the parameterization • High reliability /expression of cloud dynamics (w/ cold pool) Grid intervals：a few km

  15. Numerical techniques in the new approach • Global cloud-system resolving model • Icosahedral grid • To get a quasi-homogeneous grid • nonhydrostatic DC • To resolve cloud scale • explicit cloud expression: • To avoid the ambiguity of cumulus parameterization. NICAM ( Tomita & Satoh 2004, Satoh et al. 2008 ) • NICAM project : ~2000 • The first target machine : • Earth Simulator • Now, porting to K computer system Prof. Satoh (AORI, Tokyo univ.) Dr. Tomita (RIKEN AICS)

  16. Icosahedral grid system? Regular Icosahedron = Polyhedron with 20 triangular faces. By dividing each triangles in to 4 small triangle, we can obtain one-higher resolution. e.g. a -> b -> c-> d …

  17. NICAM current implementation Ref. Satoh et al. 2008J. Comput. Phys. / Tomita & Satoh 2004 Fluid Dyn. Res. Recent DC description paper : Tomita et al. 2011, ECMWF workshop proceeding

  18. Objection : Cloud resolving model?(Grey zone problem) • NICAM high resolution run: • 14km, 7km, 3.5km, • 1.8km, 800m, 400m • Many terms : • Cloud permitting? • Cloud resolving? • Cloud system-resolving? (GCRM) • Meso-scale resolving? • In the terms of methodology, • To avoid the ambiguity of cumulus parameterization • Methodological cloud-system resolving! The examination of impact without Cumulus Parameterization is the most important!

  19. What can the GCRM perform? e.g .NICAM 7-km simulation • Explicit expression of cloud clusters from the basic dynamical mechanism ( Cold pool dynamics ) • Explicit expression of lifecycle of typhoon (onset &development) 筑波大・田中博教授 (2010, vol.29-1, NAGARE)

  20. We can capture MJO realistically by GCRM 23 Dec. 2006 31 Dec. 2006 8 Jan. 2007 報道発表資料　図2 NICAM 7km-mesh, one-month simulation: initial = 15 Dec. 2006 Miura et al. 2007 Science

  21. We are now in the K-computer, 10 Peta-FLOPS, era !!

  22. From the demonstration to scientific knowledge Now, we can run such simulations of several decades with “K”, and make a breakthrough from the case study Earth Simulator Athena Cray XT-4 Case study (Miura et al 2007) Several weeks and month Athena Project: (Sato et al 2012)

  23. Grand Challenge project: Low-pressure Cloud cluster stratus 10000km 1000km 100km 10km 1km 100m 10m Tropical cyclone cumulus Blocking GL08 (30km) GL11 (3.5km) GL09 (14km) GL12 (1.7km) GL10 (7km) GL13 (800m)

  24. Successfully conducted the GL13(870m) simulation

  25. Essential change of convection statistics The convection structure, number of convective cells, and distance to the nearest convective cell dramatically changed around 2.0km

  26. Summary • Future direction of climate modeling • Increases of resolution, model component, ensemble • A key factor to sophisticate the atmospheric model • Cloud modeling • A new method is to express explicitly each of clouds • A main topics of climate research using K computer • Cumulus, cloud organization, tropical cyclone, MJO • High resolution ( less than 2.0km grid spacing) can resolve convection core using multiple grid.

  27. 감사합니다

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