Based on ECMWF objective analysis data, and with use of Batterworth bandpass-filtered skill and diagnostic analysis method, the interaction characteristics of low frequency wave and mean flow in midlatitudes during t...Based on ECMWF objective analysis data, and with use of Batterworth bandpass-filtered skill and diagnostic analysis method, the interaction characteristics of low frequency wave and mean flow in midlatitudes during the winter years of 1983 / 1984 and 1986 / 1987 have been studied in this paper. The main results point out the important role of the tropical convective activity on the above mentioned interaction process.展开更多
Dynamic and numerical methods are used to discuss the atmospheric response to SST thermal forcing. The results show that for planetary scale systems, the standing SST thermal forcing can quickly excite a stable atmosp...Dynamic and numerical methods are used to discuss the atmospheric response to SST thermal forcing. The results show that for planetary scale systems, the standing SST thermal forcing can quickly excite a stable atmospheric equilibrium state response, which is characterized by obvious large-scale teleconnection oscillation in east-west and south-north directions. For synoptic scale systems, the SST thermal forcing mainly excites the atmospheric low-frequency oscillation. Some basic relation and dynamic processes between SST thermal forcing and atmospheric response pattern are revealed and some new viewpoints are presented.展开更多
A simple analytical model is developed to interview the general features of the estuarine responses induced both by ocean tides and by low-frequency coastal fluctuations and wind forcings.Model estuary is assumed idea...A simple analytical model is developed to interview the general features of the estuarine responses induced both by ocean tides and by low-frequency coastal fluctuations and wind forcings.Model estuary is assumed ideally with constant depth and linearly varying breadth.The results indicate that the effects of bottom friction coefficient,the water depth and the breadth variation parameter on the estuarine response field virtually reflect the difference of the energy accumulation,transformation and dissipation in estuaries,It is found by comparison that there are obvious differences between tidally-induced and low-frequency forcing induced estuarine variations.For tidal response,bottom friction is a very important factor to affect the response magnitude,while for low-frequency response this effect becomes negligible.Thus a more simplified model for low-frequency estuarine response is produced,which gives more straightforward view to the response characteristics.Moreover,from the model solutions we deduce a general qualification for the estuarine resonance and discuss the relation between the resonance frequency and the estuarine geometry.展开更多
In order to investigate the conversion of kinetic energy from a synoptic scale disturbance （SSD; period≤seven days） to a low-frequency fluctuation （LFF; period〉seven days）, the budget equation of the LFF kinetic...In order to investigate the conversion of kinetic energy from a synoptic scale disturbance （SSD; period≤seven days） to a low-frequency fluctuation （LFF; period〉seven days）, the budget equation of the LFF kinetic energy is derived. The energy conversion is then calculated and analyzed for the summers of 1997 and 1999. The results show that the energy conversion from the SSD to the LFF is obviously enhanced in the middle and lower troposphere during the heavy rainfall, suggesting this to be one of mechanisms inducing the heavy rainfall, although the local LFF kinetic energy may not be enhanced.展开更多
文摘Based on ECMWF objective analysis data, and with use of Batterworth bandpass-filtered skill and diagnostic analysis method, the interaction characteristics of low frequency wave and mean flow in midlatitudes during the winter years of 1983 / 1984 and 1986 / 1987 have been studied in this paper. The main results point out the important role of the tropical convective activity on the above mentioned interaction process.
基金Foundation for Backbone Teachers in Higher Colleges of Education Ministry Natural Sci-ence Foundation of China (49975012)
文摘Dynamic and numerical methods are used to discuss the atmospheric response to SST thermal forcing. The results show that for planetary scale systems, the standing SST thermal forcing can quickly excite a stable atmospheric equilibrium state response, which is characterized by obvious large-scale teleconnection oscillation in east-west and south-north directions. For synoptic scale systems, the SST thermal forcing mainly excites the atmospheric low-frequency oscillation. Some basic relation and dynamic processes between SST thermal forcing and atmospheric response pattern are revealed and some new viewpoints are presented.
文摘A simple analytical model is developed to interview the general features of the estuarine responses induced both by ocean tides and by low-frequency coastal fluctuations and wind forcings.Model estuary is assumed ideally with constant depth and linearly varying breadth.The results indicate that the effects of bottom friction coefficient,the water depth and the breadth variation parameter on the estuarine response field virtually reflect the difference of the energy accumulation,transformation and dissipation in estuaries,It is found by comparison that there are obvious differences between tidally-induced and low-frequency forcing induced estuarine variations.For tidal response,bottom friction is a very important factor to affect the response magnitude,while for low-frequency response this effect becomes negligible.Thus a more simplified model for low-frequency estuarine response is produced,which gives more straightforward view to the response characteristics.Moreover,from the model solutions we deduce a general qualification for the estuarine resonance and discuss the relation between the resonance frequency and the estuarine geometry.
文摘In order to investigate the conversion of kinetic energy from a synoptic scale disturbance （SSD; period≤seven days） to a low-frequency fluctuation （LFF; period〉seven days）, the budget equation of the LFF kinetic energy is derived. The energy conversion is then calculated and analyzed for the summers of 1997 and 1999. The results show that the energy conversion from the SSD to the LFF is obviously enhanced in the middle and lower troposphere during the heavy rainfall, suggesting this to be one of mechanisms inducing the heavy rainfall, although the local LFF kinetic energy may not be enhanced.
