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Origins of intraseasonal rainfall variations over the southern South China Sea in boreal winter

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atmospheric and Oceanic Science Letters 2017年第1期10卷 44-50页

作者： CAO Xi WU Ren-Guang Center for Monsoon System Research Chinese Academy of sciences state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics Center for Monsoon System Research Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China

This study investigates the origins of intraseasonal rainfall variations over the southern South China Sea（SCS） region in boreal *** is found that intraseasonal rainfall variations over the southern SCS have different origins on the 10-20-day and 30-60-day time *** the 10-20-day time scale,large rainfall anomalies over the southern SCS are preceded by strong northerly wind anomalies associated with the East Asian winter monsoon（EAWM）,by about two *** the 30-60-day time scale,the strong EAWM-related northerly wind anomalies almost appear simultaneously with large rainfall anomalies over the southern *** addition,obvious large rainfall anomalies occur over the southeastern tropical Indian Ocean about one week before the peak southern SCS rainfall *** indicates that the convection and related circulation anomalies with origins over the tropical Indian Ocean may play an important role in inducing intraseasonal rainfall variations over the southern SCS on the 30-60-day time scale,but not on the 10-20-day time scale.

关键词： Intraseasonal rainfall anomalies southern South China Sea boreal winter 10-20-day and 30-60-day time scales

numerical SIMULATIONS OF SEA ICE WITH DIFFERENT ADVECTION SCHEMES

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Journal of Hydrodynamics 2011年第3期23卷 372-378页

作者： LIU Xi-ying state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Institute of Meteorology PLA University of Science and Technology Nanjing 211101 China

numerical simulations are carried out for sea ice with four different advection schemes to study their effects on the simulation results. The sea ice model employed here is the Sea Ice Simulator （SIS） of the geophysical fluid dynamics laboratory （GFDL） Modular Ocean Model version 4b （MOM4b） and the four advection schemes are, the upwind scheme originally used in the SIS, the Multi-Dimensional Positive Advection （MDPA） scheme, the Incremental Remapping Scheme （IRS） and the Two Step Shape Preserving （TSSP） scheme. The latter three schemes are newly introduced. To consider the interactions between sea ice and ocean, a mixed layer ocean model is introduced and coupled to the SIS. The coupled model uses a tri-polar coordinate with 120x65 grids, covering the whole earth globe, in the horizontal plane. Simulation results in the northern high latitudes are analyzed. In all simulations, the model reproduces the seasonal variation of sea ice in the northern high latitudes well. Compared with the results from the observation, the sea ice model produces some extra sea ice coverage in the Greenland Sea and Barents Sea in winter due to the exclusion of ocean current effects and the smaller simulated sea ice thickness in the Arctic basin. There are similar features among the results obtained with the introduced three advection schemes. The simulated sea ice thickness with the three newly introduced schemes are all smaller than that of the upwind scheme and the simulated sea ice velocities of movement are all smaller than that of the upwind scheme. There are more similarities shared in the results obtained with the MPDA and TSSP schemes.

关键词： advection scheme sea ice simulation

EXPERIMENTS OF SEA ICE SIMULATION

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Journal of Hydrodynamics 2005年第6期17卷 686-692页

作者： LIU Xi-ying state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics （LASG） Institute of Atmospheric Physics （IAP） Chinese Academy of Sciences Beijing 100029 China

As a substitute for the original displaced pole grids, a simple rotated spherical coordinate system was intro duced into the Community Sea Ice Model version 4（CSIM4）, which is a component of the Community Climate System Model（CCSM） of the American National Center of atmospheric Researeh（NCAR）, to deal with the ＂pole problems＂. In the new coordinates, both the geographical North Pole and South Pole lie in the model equator and grid sizes near the polar region are more uniform. With reanalysis dataset of American National Centers for Environment Prediction （NCEP） and Levitus dataset without considering sub-mixed layer heat flux, the model was integrated for 100 years with thermodynamics *** involved only in the former 49 years and both dynamic and thermodynamic processes involved in the left time. Inner consistency of model results was checked with no contradiction found. The results of last 10 years＇ model output were analyzed and it is shown that the simulated sea ice seasonal variation is rational whereas sea ice extent in the Barcnts Sea in winter is larger than that of observation, numerical experiment on influence of sub-mixed layer heat flux was also carried out and it is shown that the sub-mixed layer heat flux can modulate seasonal variation of sea ice greatly. As a model component, the sea ice model with rotated spherical coordinates was coupled with other models （the oceanic general cir culation model is the LASG/IAP Climate System Ocean Model （LICOM） with reduced grid, other models are components of NCAR CCSM2） forming a climate system model and its preliminary results were also given briefly.

关键词： sea ice numerical simulation climate system model

Influence of atmospheric heat sources over the Tibetan Plateau and the tropical western North Pacific on the inter-decadal variations of the stratosphere-troposphere exchange of water vapor

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Science China Earth sciences 2008年第8期51卷 1179-1193页

作者： ZHAN RuiFen1,2&LI JianPing2 1Shanghai Typhoon Institute of China Meteorological Administration,Shanghai 200030,China 2state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics(LASG),Institute of atmospheric Physics,Chinese Academy of sciences,Beijing 100029,China 1. Shanghai Typhoon Institute of China Meteorological Administration Shanghai 200030 China 2. state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

This study investigates the Stratosphere-Troposphere Exchange(STE) of water vapor,emphasizes its interdecadal variations over Asia in boreal summer,and discusses the influences of atmospheric heat sources over the Tibetan Plateau and the tropical western North Pacific(WNP) on them by using the Wei method with reanalysis data from the European Centre for Medium-Range Weather Forecasts(ECMWF) for the years of *** climatology shows that the upward transport of water vapor across the tropopause in boreal summer is the most robust over the joining area of the South Asian Peninsula and Indian-Pacific Oceans(defined as AIPO).The upward transport over there can persistently convey the abundant water vapor into the stratosphere and then influence the distribution and variation of the stratospheric water *** analysis shows that interdecadal variations of the water vapor exchange over the AIPO are significant,and its abrupt change occurred in the mid-1970s and the early *** these three periods,as important channels of the water vapor exchange,the effect of Bay of Bengal-East Asia as well as South China Sea was gradually weakening,while the role of the WNP becomes more and more *** studies show that atmospheric heat sources over the Tibetan Plateau and the WNP are two main factors in determining the interdecadal variations of water vapor *** thermal influences over the Tibetan Plateau and the WNP have been greatly adjusted over the pass 44 *** synthesis influences the interdecadal variations of the water vapor exchange by changing the Asian summer monsoon,but their roles vary with time and *** after 1992,the influence of heat source over the Tibetan Plateau remarkably weakens,while the heat source over the WNP dominates the across-tropopause water vapor *** have important implications for understanding the transport of other components in the atmosphere and estimating the impact of human activities(

关键词： Tibetan Plateau tropical western North Pacific atmospheric heat source STE inter-decadal variations

A semi-implicit semi-Lagrangian global nonhydrostatic model and the polar discretization scheme

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Science China Earth sciences 2007年第12期50卷 1885-1891页

作者： YANG XueSheng1,CHEN JiaBin2,HU JiangLin1,CHEN DeHui1,SHEN XueShun1,ZHANG HongLiang1 1 state key laboratory of Severe Weather,Chinese Academy of Meteorological sciences,Beijing 100081,China 2 state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics,Institute of atmospheric Physics,Beijing 100029,China 1. state key laboratory of Severe Weather Chinese Academy of Meteorological Sciences Beijing 100081 China 2. state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics Institute of Atmospheric Physics Beijing 100029 China

The Global/Regional Assimilation and PrEdiction System(GRAPES) is a newly developed global non-hydrostatic numerical prediction model,which will become the next generation medium-range opera-tional model at China Meteorological Administration(CMA).The dynamic framework of GRAPES is featuring with fully compressible equations,nonhydrostatic or hydrostatic optionally,two-level time semi-Lagrangian and semi-implicit time integration,Charney-Phillips vertical staggering,and complex three-dimensional pre-conditioned Helmholtz solver,*** the singularity of horizontal momentum equations at the poles,the polar discretization schemes are described,which include adoption of Arakawa C horizontal grid with ν at poles,incorporation of polar filtering to maintain the computational stability,the correction to Helmholtz equation near the poles,as well as the treatment of semi-Lagrangian interpolation to improve the departure point accuracy,*** balanced flow tests validate the rationality of the treatment of semi-Lagrangian departure point calculation and the polar discretization during long time *** and Suarez tests show that the conservation proper-ties of GRAPES model are quite good.

关键词： nonhydrostatic, global model, semi-implicit, semi-Lagrangian, polar discretization, conservation

Improved ENSO simulation in regional coupled GCM using regressive correction method

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Science China Earth sciences 2007年第8期50卷 1258-1265页

作者： FU WeiWei1 & ZHOU GuangQing2 1 Nansen-Zhu International Research Center (NZC), Institute of atmospheric Physics, Chinese Academy of sciences (CAS), Beijing 100029, China 2 state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics (LASG), Institute of At-mospheric Physics, CAS, Beijing 100029, China 1. Nansen-Zhu International Research Center (NZC) Institute of Atmospheric Physics Chinese Academy of Sciences (CAS) Beijing 100029 China 2. state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics (LASG) Institute of Atmospheric Physics CAS Beijing 100029 China

A regressive correction method is presented with the primary goal of improving ENSO simulation in regional coupled GCM. It focuses on the correction of ocean-atmosphere exchanged fluxes. On the basis of numerical experiments and analysis, the method can be described as follows: first, driving the ocean model with heat and momentum flux computed from a long-term observation data set; the pro-duced SST is then applied to force the AGCM as its boundary condition; after that the AGCM’s simula-tion and the corresponding observation can be correlated by a linear regressive formula. Thus the re-gressive correction coefficients for the simulation with spatial and temporal variation could be obtained by linear fitting. Finally the coefficients are applied to redressing the variables used for the calculation of the exchanged air-sea flux in the coupled model when it starts integration. This method together with the anomaly coupling method is tested in a regional coupled model, which is composed of a global grid-point atmospheric general circulation model and a high-resolution tropical Pacific Ocean model. The comparison of the results shows that it is superior to the anomaly coupling both in reducing the coupled model ‘climate drift’ and in improving the ENSO simulation in the tropical Pacific Ocean.

关键词： anomaly coupling regressive correction method regional coupled model ENSO simulation

A numerical CALCULATION METHOD FOR EIGENVALUE PROBLEMS OF NONLINEAR INTERNAL WAVES

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Journal of Hydrodynamics 2009年第3期21卷 373-378页

作者： SHI Xin-gang FAN Zhi-song LIU Hai-long College of Physical and Environmental Oceanography Ocean University of China Qingdao 266100 China state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

Generally speaking, the background shear current U（z） must be taken into account in eigenvalue problems of nonlinear internal waves in ocean, as is different from those of linear internal waves. A numerical calculation method for eigenvalue problems of nonlinear internal waves is presented in this paper on the basis of the Thompson-Haskell＇s calculation method. As an application of this method, at a station （21°N, 117°15′E） in the South China Sea, a modal structure and parameters of nonlinear internal waves are calculated, and the results closely agree with the calculated results based on observation by Yang et al..

关键词： internal waves eigenvalue problem modal structure numerical method

Evolution of desertification in a two-dimensional energy balance model coupled with thermodynamics and dynamics

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Science China Earth sciences 2010年第11期53卷 1726-1733页

作者： CHAO JiPing1,2 & LI YaoKun3,4 1National Marine Environmental Forecasting Center, Beijing 100081, China 2First Institute of Oceanography, state Oceanic Administration, Qingdao 266061, China 3state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics, Institute of atmospheric Physics, Chinese Academy of sciences, Beijing 100029, China 4Graduate University of Chinese Academy of sciences, Beijing 100049, China 1. National Marine Environmental Forecasting Center Beijing 100081 China2. First Institute of Oceanography State Oceanic Administration Qingdao 266061 China3. State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China4. Graduate University of Chinese Academy of Sciences Beijing 100049 China

The relationship between desert evolution and change in albedo has been investigated quasi-analytically using a zonal mean two-dimensional energy balance model which considers the radiation transmission process due to thermodynamics and bound- ary layer movement caused by kinetics. A climate state including temperature, zonal wind, meridional wind and vertical wind can be simulated according to the current zonal distribution of albedo. Given desert distribution, characterized by the value and distribution of albedo, the response of climate on albedo has been studied to analyze the evolution of desert climate. One significant result is that the simple model can reproduce mean meridional circulation. Another result indicates that climate corresponds to two equilibria. This happens when the junction temperature between vegetation and desert is higher than a certain critical value. As for the first equilibrium, the desert belt is predicted to move southward in the northern hemisphere with the increasing values of albedo, which corresponds to the current trend of climate change. For the second equilibrium, vegetation will expand northward with increasing values of albedo, which would indicate a narrowing of the desert belt. In order to determine if the two equilibria exist, new physical models are needed.

关键词： two-dimensional energy balance model desertification two equilibria

Comparison of the global air-sea freshwater exchange evaluated from independent datasets

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Progress in Natural Science:Materials International 2003年第8期 68-73页

作者： ZHOU Tianjun(state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics (LASG), Institute of atmospheric Physics, Chinese Academy of sciences, Beijing 100029, China) state key laboratory of numerical modeling for atmospheric sciences and geophysical fluid dynamics LASG Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

The implied air-sea freshwater flux is examined in two reanalysis datasets provided respectively by European Center forMedium-range Weather Forecasts and National Center for Environmental Prediction. Not only for annual mean state but also for seasonalvariation, two reanalyses agree qualitatively well with each other, and both can reproduce reasonably the global distribution of E-P (i. *** minus Precipitation). In the view of quantitative comparison, however, remarkable difference has been found on regionalscales, especially over the middle and lower latitudes, with some local disagreement exceeding 100 cm/yr. One important difference be-tween current and previous evaluation is the new found net evaporation over the high latitude North Atlantic, which is demonstrated to re-sult from the transient disturbances during boreal winter.

关键词： air-sea freshwater exchange reanalysis datasets.