Since the end of the Cold War,the United States has turned out to be the sole world superpower and possessed the unmatched power,and its international status and security situation reached the best period in its histo...Since the end of the Cold War,the United States has turned out to be the sole world superpower and possessed the unmatched power,and its international status and security situation reached the best period in its history.Although the U.S.power has declined relatively,its advantages have not changed substantially.The advantages of the U.S.power determine the essence of the U.S.global strategy,and since the end of the Cold War remains almost intact,which is committed to maintenance of the U.S.hegemony,including 3 core goals:maintaining security,expanding economy and promoting democracy.Since the end of the Cold War,all U.S.presidents have adhered to this hegemonic strategy while making some major adjustments,with some changing expressions and the priorities of the strategic goals.It should be pointed out that there is an important and possibly dangerous trend in the adjustments,,which is the gradual disappearance of strategic flexibility and strategic ambiguity.In other words,these global strategic adjustments after the Cold War have been increasingly focusing on China and the Asia-Pacific region.This trend is likely to continue in the second term of President Obama and will affect the development of China-U.S.relations to a large extent.展开更多
The operational numerical weather prediction system established by the China Meteorological Administration(CMA),based on the Global/Regional Assimilation and Prediction System(GRAPES)model,adopts the classical semi-im...The operational numerical weather prediction system established by the China Meteorological Administration(CMA),based on the Global/Regional Assimilation and Prediction System(GRAPES)model,adopts the classical semi-implicit semi-Lagrangian(SISL)time integration algorithm.This paper describes a major upgrade to the dynamical core of the CMA global forecast system(CMA-GFS),which was successfully incorporated into operation in 2020.In the upgrade,the classical SISL is further developed into a predictor–corrector scheme,a three-dimensional(3D)reference profile instead of the original isothermal reference profile is applied when implementing the semi-implicit algorithm,and a hybrid terrain-following vertical coordinate system is also applied.The new version of the dynamical core greatly improves the model performance,the time integration reaches second-order accuracy,the time step can be extended by 50%,and the efficiency is greatly improved(by approximately 30%).Atmospheric circulation simulation is systematically improved,and deviations in temperature,wind,and humidity are reduced.The new version of the dynamical core provides a solid foundation for further development of the entire operational system of the CMA.展开更多
The most eye-catching event at the start of 2017 might be U.S.business tycoon Donald Trump officially embarking on his White House career.Avoiding the usual hypocrisy from traditional politicians,who tend to break the...The most eye-catching event at the start of 2017 might be U.S.business tycoon Donald Trump officially embarking on his White House career.Avoiding the usual hypocrisy from traditional politicians,who tend to break their campaign promises once assuming power, the alleged political layman began honoring his commitments immediately after walking into the West Wing.展开更多
The first-ever open recruitment for the top UN post draws attention The UN kicked off the first-ever public examination of applicants seeking to lead one of the world’s largest intergovernmental organizations on Apri...The first-ever open recruitment for the top UN post draws attention The UN kicked off the first-ever public examination of applicants seeking to lead one of the world’s largest intergovernmental organizations on April 12,when interviews for the nine candidates vying to replace Secretary General Ban Ki-moon began.展开更多
文摘Since the end of the Cold War,the United States has turned out to be the sole world superpower and possessed the unmatched power,and its international status and security situation reached the best period in its history.Although the U.S.power has declined relatively,its advantages have not changed substantially.The advantages of the U.S.power determine the essence of the U.S.global strategy,and since the end of the Cold War remains almost intact,which is committed to maintenance of the U.S.hegemony,including 3 core goals:maintaining security,expanding economy and promoting democracy.Since the end of the Cold War,all U.S.presidents have adhered to this hegemonic strategy while making some major adjustments,with some changing expressions and the priorities of the strategic goals.It should be pointed out that there is an important and possibly dangerous trend in the adjustments,,which is the gradual disappearance of strategic flexibility and strategic ambiguity.In other words,these global strategic adjustments after the Cold War have been increasingly focusing on China and the Asia-Pacific region.This trend is likely to continue in the second term of President Obama and will affect the development of China-U.S.relations to a large extent.
基金Supported by the National Natural Science Foundation of China(42090032 and 42275168).
文摘The operational numerical weather prediction system established by the China Meteorological Administration(CMA),based on the Global/Regional Assimilation and Prediction System(GRAPES)model,adopts the classical semi-implicit semi-Lagrangian(SISL)time integration algorithm.This paper describes a major upgrade to the dynamical core of the CMA global forecast system(CMA-GFS),which was successfully incorporated into operation in 2020.In the upgrade,the classical SISL is further developed into a predictor–corrector scheme,a three-dimensional(3D)reference profile instead of the original isothermal reference profile is applied when implementing the semi-implicit algorithm,and a hybrid terrain-following vertical coordinate system is also applied.The new version of the dynamical core greatly improves the model performance,the time integration reaches second-order accuracy,the time step can be extended by 50%,and the efficiency is greatly improved(by approximately 30%).Atmospheric circulation simulation is systematically improved,and deviations in temperature,wind,and humidity are reduced.The new version of the dynamical core provides a solid foundation for further development of the entire operational system of the CMA.
文摘The most eye-catching event at the start of 2017 might be U.S.business tycoon Donald Trump officially embarking on his White House career.Avoiding the usual hypocrisy from traditional politicians,who tend to break their campaign promises once assuming power, the alleged political layman began honoring his commitments immediately after walking into the West Wing.
文摘The first-ever open recruitment for the top UN post draws attention The UN kicked off the first-ever public examination of applicants seeking to lead one of the world’s largest intergovernmental organizations on April 12,when interviews for the nine candidates vying to replace Secretary General Ban Ki-moon began.
