Of great importance for guiding numerical weather and climate predictions, understanding predictability of the atmosphere in the ocean − atmosphere coupled system is the first and critical step to understand predictability of the Earth system. However, previous predictability studies based on prefect model assumption usually depend on a certain model. Here we apply the predictability study with the Nonlinear Local Lyapunov Exponent and Attractor Radius to the products of multiple re-analyses and forecast models in several operational centers to realize general predictability of the atmosphere in the Earth system. We first investigated the predictability characteristics of the atmosphere in NCEP, ECMWF and UKMO coupled systems and some of their uncoupled counterparts and other uncoupled systems. Although the ECMWF Integrated Forecast System shows higher skills in geopotential height over the tropics, there is no certain model providing the most precise forecast for all variables on all levels and the multi-model ensemble not always outperforms a single model. Improved low-frequency signals from the air − sea and stratosphere − troposphere interactions that extend predictability of the atmosphere in coupled system suggests the significance of air − sea coupling and stratosphere simulation in practical forecast development, although uncertainties exist in the model representation for physical processes in air − sea interactions and upper troposphere. These inspire further exploration on predictability of ocean and stratosphere as well as sea − ice and land processes to advance our understanding of interactions of Earth system components, thus enhancing weather − climate prediction skills.
From winter 2009 to spring 2010, southern China suffered from an extensive and lengthy drought. Subsequently, southern China
experienced torrential rains a dozen times during the flood season of April–June. The prolonged drought and subsequent intensive
rainfall dramatically altered the hydrodynamic conditions of the karst areas, causing hundreds of widely distributed karst
collapses, with extensive damage to houses and fields and necessitating the evacuation of many people. Understanding the causes
of these collapses will provide a scientific basis for the prediction or prevention of the related risk. Thus, a geologic
survey of karst collapses was performed that systematically allowed to analyze the basic geological conditions, groundwater
hydrodynamic conditions, overlying strata properties, and environmental and climatic conditions in southern China. The results
showed that environmental and climatic changes, especially the drastic changes in rainfall, gave rise to striking changes
in karst hydrodynamic conditions that accelerated infiltration, suffosion, dissolution, and transportation rates and also
changed the physical and mechanical properties of the strata overlying karst caves. These stressors triggered or facilitated
both cave formation and collapse. 相似文献