Geoscience

Influence of Oceanic Channel Dynamics on the Pacific ENSO

Scientists of the Key Lab of Ocean Circulation and Waves of the CAS Institute of Oceanology in Qingdao led by Dr. Yuan Dongliang have discovered the “Oceanic Channel Dynamics” for the Indian Ocean Dipole (IOD) to influence the Pacific ENSO through the variability of the Indonesian Throughflow recently. The research group have published two papers consecutively in the journal of J. Climate, based both on numerical experiments and observational data analyses, suggesting that the equatorial Kelvin waves in the equatorial Indian Ocean during the IOD events can propagate into the equatorial western Pacific Ocean through the Indonesian seas. These Kelvin waves produce temperature anomalies in the subsurface warm pool, which propagate to the eastern equatorial Pacific Ocean to be amplified by the ocean-atmosphere coupling. The series process lead to ENSO events and other tropical climate variability in the year following the IOD. Studies have suggested that the ENDO events forced by the IOD through the oceanic channel dynamics can be predicted beyond the lead time of one year, in which the ocean thermocline dynamics have provided the key mechanism of information transmission for the ENSO prediction to penetrate through the spring predictability barrier. Analyses further suggest that the memory of the atmospheric bridge cannot last for a year, whereas the temperature anomalies in the ocean thermocline can persist until the fall of the second year. The scientists have further diagnosed 23 coupled climate models of the CMIP5 projects, and have assessed the oceanic channel and the atmospheric bridge dynamics in the simulations of these models, which provide a basis for the improvement of model simulations and predictions of the tropical Indo-Pacific climate variability. Some of the results have been published in the latest issue of Advanced Atmosphere Science. They have also studied the nonlinear dynamics of two western boundary currents colliding at the entrance of the Indonesian Throughflow and have discovered nonlinear hysteresis and periodic eddy shedding in the circulation patterns, which are in agreement with the latest observations in the western Pacific Ocean. The results are published in Journal of Physical Oceanography. The series of publication on the oceanic channel theory of the Indo-Pacific climate interactions have attracted attention of the international community. In the European Geophysical Union annual meeting in Vienna in 2013, Dr. Yuan was invited to organize a session titled “Variability and predictability of climate in the Indo-Pacific Ocean”.

Patents Granted to Early Warning System of Debris Flow

Recently, a research team led by Prof. Ou Guoqiang from the Institute of Mountain Hazards and Environment, CAS (IMHE) was granted two National Invention Patents titled "A Method for Debris Flow Warning" (Patent No: ZL201110046589.5) and "A Method for Debris Flow Warning in the Region Lack of Rainfall Data" (Patent No: ZL201110095301.3). The actual work was focused on the mountainous areas where rainfall data and records on the debris flow formation zones are not complete or not available. After several years’ research, the researchers put forward two methods respectively for rainfall threshold calculation on the base of the theory of hydraulic initiation mechanism of debris flow and analogy analysis in the similar regions with abundant rainfall data. These two methods are proved to be efficient and successful in solving the key issues remained in areas short of rainfall data and providing a solution for early warning of storm-induced debris flow. These methods are also characterized by extensive applicability and better operability. Based on these two methods, the research team has selected two demonstration sites for monitoring and early warning of landslides and debris flows in the key zones for soil and water conservation in the Upper Yangtze River,