Challenges in monsoon system study

1. Challenges in monsoon system study • The monsoon systems are manifested as land-atmosphere-ocean coupled systems, exhibiting a variety of time and space scales that are governed by complex physical processes and their interactions. • Due to our lack of understanding these processes and interactions, large uncertainties still exist in prediction of the monsoons on local, regional, and continental-scales. • Monsoon predictions require better models, and better models require improved physical parameterizations, which in turn require more comprehensive observations.  • Since the monsoon systems possess a large range of variability from diurnal to decadal time scales, prediction is a challenging test for the modelling community.  • Given the importance of the monsoons in driving the energy and water cycle, improving model physics in monsoon regions will result in better models for other applications such as global change, and water resource assessments.

2. This workshop was a unique and timely opportunity to promote a new initiative of the pan-WCRP monsoon system prediction studies,which should be an essential part of the new WCRP strategy.

3. WS recommendations (selected) #1 • Targeted workshops are envisioned as an important mode of interaction for sustaining CLIVAR and GEWEX interactions. These can be held in conjunction with existing panel meetings, as sessions at conferences, or independently. • The near-term (1-2 years) goal is to improve the simulation of the diurnal cycle of precipitation and convection in global models by making use of regional climate models and cloud-resolving models that have more comprehensive physics. This is seen as the primary near-term goal that will crosscut the expertise of CLIVAR and GEWEX.

4. WS recommendations (selected) #2 • Improved modeling of the intraseasonal oscillation, with large-scale convection in the tropics on a time scale of ~30-70 days. This phenomenon straddles numerical weather prediction and climate, and is a potential source of predictability that has not been realized due to its poor representation in models. • Need for more process studies and modeling of the Maritime continent and the Indian Ocean. • Better understanding of the atmospheric moisture distribution and transport. • Sensitivity testing to determine the resolution necessary in global models to simulate multi-scale interactions that dominate the Earth’s monsoon systems.

5. WS recommendations (selected) #3 • The decay of the present observing system needs to be reversed.⇒role of GEOSS is important! • Improved (and sustained) observations are needed over sparsely sampled regions of the tropical oceans, especially the Indian Ocean. • Better observations of land surface conditions are needed (e.g., soil moisture, snow cover, snow depth) for understanding processes, and because these quantities can serve as boundary conditions for model simulations. • The role of aerosol and dust and its impact on the development of monsoon precipitation should be investigated, though at present these may be secondary to errors in the basic structure of monsoon simulations.

6. 00-05LT [mm/hr] Diurnal cycle of rainfall by TRMM-PR The most humid area in the tropics show large DC in time-space. (Ichikawa and Yasunari, 2006 J. Climate)

7. OLR and wind (850hPa) MJO disturbance developed between Jan to Feb in 2001 Jan21-31 Feb1-10 ISO propagated through the islands, with apparent Kelvin-Rossby response. Feb11-20 Feb21-28 Ichikawa and Yasunari, 2007 submitted to GRL.

8. 黒線・・・日周変化フィルタをかけた降雨量　TRMM3B42黒線・・・日周変化フィルタをかけた降雨量　TRMM3B42 (正偏差0.1、0.2、0.4、0.6、0.8、1mm/h) 白線・・・30-60日フィルタをかけたＯＬＲ(負偏差-5、-20W/m2) 下地・・・700hPa高度の東西風速(最も薄い色のみ東風を示す!!) Comparison with westward propagating case (June 2001) Feb. 2001 Jun.2002 ここは 東風領域 ここは 東風領域 地形 [m/s] 地形 [m/s] 東風 東風 西風 西風 [m] [m]

9. Fine structure of MJO shaded・・・OLR(－190－240－　[W/m2]) white・・・zonal wind at 600hPa(solid:2,dash:10[m/s]) color・・・diurnal cycle filtered rainfall 0.2, 0.4 [mm/h] Time-longitude section of rainfall between Eq-5S Propagating rainfall activity associated with the diurnal cycle over and around the island ↓↓ Propagating diurnal disturbance (PDD) 15‐20m/s (Ichikawa and Yasunari, 2007 submitted to GRL.)

10. Abnormally heavy flood occurredin southeast Asia during winter monsoon surge in 2006/2007 This extreme event occurred in abnormally warm winter monsoon in east Asia (under the global warming trend?!).

11. Rainfall amount and mean low-level(925hPa) circulations during heavy rainfall events of 17Dec.-20Dec.2006

12. Time-sequence of V 925hpaStrong NE monsoon surge was likely to cause heavy rainfall events. 15DEC 16DEC 17DEC 18DEC 19DEC 20DEC

13. Heavy rainfall was modulated by diurnal cycle of meso-scale convective system.

14. MJO Flood over Malay peninsula →stagnant rainfall Heavy rainfall over Jawa 2N-6NAverage Flood over Malay peninsula →gradual eastward propagation Heavy rainfall events were also associated with MJO from IO.

15. Meso-scale disturbances originated from DC convective sytem over Tibetan Plateau(Yasunari and Miwa, JMSJ, 2006) Tibet P. Tibet P. Eastern Edge of Plateau

16. Diurnally-developed convergence line in some cases expand toward the eastern edge of the Plateau, to form meso-αsystems over Meiyu Frontal Zone (Plateau Edge Cyclogenesis:PEC)(Yasunari and Miwa, JMSJ, 2006) High-resolution GAME RA data used

17. Scientific rationales for AMY (IMY) and YOTC • Multi-scale interactions from meso-scale to planetary-scale are essential for dynamics and prediction of ISV and seasonal march of monsoons, which include time scales from DC to ISV and SC. • Global-scale simultaneous satellite observations with high-resolution (with space & time) are essential for resolving these interactions, through 30m. to 1hr obs. of the geostationary met. satellites. • Coordination of in-situ regional observations and modelings relevant to various international/national projects should be optimized in conjunction with the intensive satellite observations. • High-resolution reanalyses based on the data of these IOPs (for boreal summer and winter monsoon) will provide invaluable data for improving daily to seasonal predictions.

18. In this workshop, we need to discuss • How to coordinate various regional experiments during IOP 08-09 • Optimized operation of satellite observations • Data exchange and management policy • Cooperation in modeling acitivity including capacity buildings in monsoon countries • Common products for monsoon study and prediction, e.g., high-resolution data assimilation

20. Objectives of the Workshop • This Pan-WCRP workshop on the monsoon climate systems aims to integrate our current understanding of fundamental physical processes that govern the various monsoon climate systems, and to promote better predictions using a hierarchy of models. • This workshop should also be a unique and timely opportunity to promote a new initiative of the pan-WCRP monsoon system prediction studies, which should be an essential part of the forthcoming COPES (Coordinated Observation and Prediction of the Earth System) as a new WCRP strategy. • Organizing committee: T. Yasunari (Co-chair), K. R. Sperber (Co-chair), W. Higgins, K.M. Lau, J. McCreary, C.R.Mechoso, J. Polcher, K. Puri, J. Slingo, C. Thorncroft, B. Wang, G.-X., Wu

21. The follow-up workshop on diurnal cycle of rainfall over land & ocean • was held as part of the Sysmatic Error Workshop of WGNE in San Francisco, February 12-16 2007. • 1st. International workshop on AMY will be held in Beijing, April 23-25, 2007. • 2nd Pan-WCRP monsoon workshop to be expected in conjunction with the 1st Science workshop on the new CEOP, in Bali, Indonesia, September 2007.