Rainfall characteristics and convective properties of monsoon precipitation systems over South China (SC) and the Yangtze and Huai River basin (YHRB) are investigated using multiple satellite products, surface rainfall observations, NCEP reanalysis, and weather maps. Comparisons between SC and YHRB are made for their monsoon active periods and their subseasonal variations from the premonsoon to monsoon and further to postmonsoon periods. The principal findings are as follows. (i) During the monsoon active period, region-averaged rain accumulation is greater in SC due to more frequent occurrence of precipitation systems; however, heavy rainfall contribution is greater in YHRB. These differences are related to more intense convective motion over the YHRB in association with the flatter land and more concurrent presence and stronger intensity of the low-level vortices and surface fronts. (ii) Largely in agreement with the subseasonal variations of the atmospheric thermodynamic conditions, convective intensity is enhanced progressively from the premonsoon to the monsoon and further to the postmonsoon period in both regions, as suggested by most convection proxies, except for lightning flash rate, which decreases substantially over SC but increases slightly over the YHRB from the premonsoon to the monsoon period. (iii) Compared to the monsoon active period, precipitation storms in both regions during the postmonsoon and monsoon break periods are more controlled by local instability due to solar heating but less controlled by larger-scale weather systems. This scale difference in the driving mechanisms leads to the smaller horizontal extent of the precipitation systems during the postmonsoon and monsoon break periods and also to the more pronounced afternoon peaks in precipitation system occurrence in the postmonsoon period.

The structure prediction at the atomic level is emerging as a state-of-the-art approach to accelerate the functionality-driven discovery of materials. By combining the global swarm optimization algorithm with first-principles thermodynamic calculations, it exploits the power of current supercomputer architectures to robustly predict the ground state and metastable structures of materials with only the given knowledge of chemical composition. In this Review, we provide an overview of the basic theory and main features of our as-developed CALYPSO structure prediction method, as well as its versatile applications to design of a broad range of materials including those of three-dimensional bulks, two-dimensional reconstructed surfaces and layers, and isolated clusters/nanoparticles or molecules with a variety of functional properties. The current challenges faced by structure prediction for materials discovery and future developments of CALYPSO to overcome them are also discussed.

The variability of summer precipitation in the southeastern United States is examined in this study using 60-yr (1948-2007) rainfall data. The Southeast summer rainfalls exhibited higher interannual variability with more intense summer droughts and anomalous wetness in the recent 30 years than in the prior 30 years . Such intensification of summer rainfall variability was consistent with a decrease of light (0.1-1 mm day 21 ) and medium (1-10 mm day 21 ) rainfall events during extremely dry summers and an increase of heavy (.10 mm day 21) rainfall events in extremely wet summers. Changes in rainfall variability were also accompanied by a southward shift of the region of maximum zonal wind variability at the jet stream level in the latter period. The covariability between the Southeast summer precipitation and sea surface temperatures (SSTs) is also analyzed using the singular value decomposition (SVD) method. It is shown that the increase of Southeast summer precipitation variability is primarily associated with a higher SST variability across the equatorial Atlantic and also SST warming in the Atlantic.

An interdecadal shift in the variability and mean state of the tropical Pacific Ocean is investigated within the context of changes in El Niñ o-Southern Oscillation (ENSO). Compared with 1979-99, the interannual variability in the tropical Pacific was significantly weaker in 2000-11, and this shift can be seen by coherent changes in both the tropical atmosphere and ocean. For example, the equatorial thermocline tilt became steeper during 2000-11, which was consistent with positive (negative) sea surface temperature anomalies, increased (decreased) precipitation, and enhanced (suppressed) convection in the western (central and eastern) tropical Pacific, which reflected an intensification of the Walker circulation.The combination of a steeper thermocline slope with stronger surface trade winds is proposed to have hampered the eastward migration of the warm water along the equatorial Pacific. As a consequence, the variability of the warm water volume was reduced and thus ENSO amplitude also decreased. Sensitivity experiments with the Zebiak-Cane model confirm the link between thermocline slope, wind stress, and the amplitude of ENSO.