A Dynamic Coupling of Ocean and Plate Motion

Plate motion representing a remarkable Earth process is widely attributed to several primary forces such as ridge push and slab pull. Recently, we have presented that the ocean water pressure against the wall of continents may generate enormous force on continents. Continents are physically fixed on the top of the lithosphere that has been already broken into individual plates, this attachment enables the force to be laterally transferred to the lithospheric plates. In this study, we combine the force and the existing plate driving forces (i.e., ridge push, slab pull, collisional, and shearing) to account for plate motion. We show that the modelled movements for the South American, African, North American, Eurasian, Australian, Pacific plates are well agreement with the observed movements in both speed and azimuth, with a Root Mean Square Error (RMSE) of the modelled speed against the observed speed of 0.91, 3.76, 2.77, 2.31, 7.43, and 1.95 mm/yr, respectively.

Response of Atmospheric Low-frequency Wave to Oceanic Forcing in the Tropics

The effects of oceanic forcing on the atmospheric low-frequency wave (LFW for short) in the tropics are analyzed, where ocean and atmosphere are taken as an independent system, respectively. Here oceanic effects are parameterized as evaporation-wind feedback (EWF for short) and forcing of SST. Under the modulation of EWF, forcing of SST plays a different role from that without EWF, So LFWs are diabatic waves, forced by the interactions of multiple factors, in the tropics. Key words Atmospheric LFW - Oceanic forcing - EWF - Radiative cooling - SST This paper was supported by “ First Institute of Oceanic Sciences, State Oceanic Administration, State Key Laboratory of Geophysical Fluid Dynamics and Numerical Modeling”.

Trends in Significant Wave Height and Surface Wind Speed in the China Seas Between 1988 and 2011

Wind and waves are key components of the climate system as they drive air-sea interactions and influence weather systems and atmospheric circulation. In marine environments, understanding surface wind and wave fields and their evolution over time is important for conducting safe and efficient human activities, such as navigation and engineering. This study considers long-term trends in the sea surface wind speed(WS) and significant wave height(SWH) in the China Seas over the period 1988–2011 using the Cross-Calibrated Multi-Platform(CCMP) ocean surface wind product and a 24-year hindcast wave dataset obtained from the WAVEWATCH-III(WW3) wave model forced with CCMP winds. The long-term trends in WS and SWH in the China Seas are analyzed over the past 24 years to provide a reference point from which to assess future climate change and offshore wind and wave energy resource development in the region. Results demonstrate that over the period 1988–2011 in the China Seas: 1) WS and SWH showed a significant increasing trend of 3.38 cm s^(-1)yr^(-1) and 1.52 cm yr^(-1), respectively; 2) there were notable regional differences in the long-term trends of WS and SWH; 3) areas with strong increasing trends were located mainly in the middle of the Tsushima Strait, the northern and southern areas of the Taiwan Strait, and in nearshore regions of the northern South China Sea; and 4) the long-term trend in WS was closely associated with El Ni?o and a significant increase in the occurrence of gale force winds in the region.

Ocean contributes to the melting of the Jakobshavn Glacier front

The Jakobshavn Glacier(JG)in Greenland is one of the most active glaciers in the world.It was close to balance before 1997 but this was followed by a sudden transition to rapid thinning.The reason for the change remains unclear.In this study,The NASA Pre-IceBridge ice thickness data are collected to monitor the melting of JG front.The surface elevation decreased by around 90 m from 1995 to 2002 on the floating front.A distributed energy balance model is developed to estimate the energy balance of JG front in the past 30 years(1986-2016).The results indicate that multi-year average energy fluxes absorbed by the floating front of JG from the ocean were about 500 Wm^-2 from 1986 to 2016.This is approximately two times of the energy fluxes from atmosphere during the same period.The energy fluxes from the ocean increased from 200 to 600 Wm^-2during the period from 1990 to 1998 while energy fluxes from the atmosphere remained stable at about 250 Wm^-2.These results demonstrate that ocean contributes more to the melting of the JG front,and suggest that bottom surface melting must have a profound influence on marine-terminating glacier dynamics.

Mechanisms for the Formation of Northeast China Cold Vortex and Its Activities and Impacts:An Overview

In the mid 20th century, great efforts were made to investigate the formation process of high-latitude cold vortex, which is regarded as a major weather system in the atmospheric circulation. In the late 1970s, Chinese researchers noticed that the Northeast China cold vortex （NECV） is an active and frequently occurring weather system over Northeast Asia, which is generated under specific conditions of topography and land-sea thermal contrast on the local and regional scales. Thereby, the NECV study was broadened to include synoptic situations, mesoscale and dynamic features, the heavy rain process, etc. Since the 21st century, in the context of the global warming, more attention has been paid to studies of the mechanisms that cause the NECV variations during spring and early summer as well as the climatic impacts of the NECV system. Note that the NECV activity, frequent or not, not only affects local temperature and precipitation anomalies, but also regulates the amount of precipitation over northern China, the Huai River basin, and the middle and lower reaches of Yangtze River. The NECV influence can even reach the Guangdon~ Guangxi region. However, compared to the achievements for the blocking system study, theoretical studies with regard to the NECV system are still insufficient. Research activities regarding the mechanisms for the NECV formation, particularly theoretical studies using linear or weak nonlinear methods need to be strengthened in the future. Meanwhile, great efforts should be made to deepen our understanding of the relations of the NECV system to the oceanic thermal forcing, the low-frequency atmospheric variations over mid-high latitudes, and the global warming.