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Sensitivity of sea ice and ocean simulations to sea ice salinity in a coupled global climate model

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Science china Earth sciences 2010年第6期53卷 911-918页

作者： LIU JiPing state key {2. of Numerical Modeling for atmospheric sciences and Geophysical Fluid Dynamics, institute of atmospheric physics, chinese academy of sciences, beijing, 100029, china state key {2. of Numerical Modeling for atmospheric sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China

The impacts of the spatiotemporal variations of sea ice salinity on sea ice and ocean characteristics have not been studied in detail, as the existing climate models neglect or misrepresent this process. To address this issue, this paper formulated a parameterization with more realistic sea ice salinity budget, and examined the sensitivity of sea ice and ocean simulations to the ice salinity variations and associated salt flux into the ocean using a coupled global climate model. Results show that the inclusion of such a parameterization leads to an increase and thickening of sea ice in the Eurasian Arctic and within the ice pack in the Antarctic circumpolar region, and a weakening of the North Atlantic Deep Water and a strengthening of the Antarctic Bottom Water. The atmospheric responses associated with the ice changes were also discussed.

关键词： sea ice salinity coupled global climate model Arctic and Antarctic

Input function and simulated distributions of tritium in the North Pacific

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Science china Earth sciences 2010年第3期53卷 441-453页

作者： BA Qi1,2.& XU YongFu1 1 state key {2. of atmospheric Boundary Layer physics and atmospheric Chemistry, institute of atmospheric physics, chinese academy of sciences, beijing 100029, china 2.Graduate University of chinese academy of sciences, beijing 100049, china state key {2. of atmospheric Boundary Layer physics and atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Graduate University of chinese academy of sciences Beijing China

An ocean general circulation model (OGCM) of the North Pacific with a southern open boundary condition is used to simulate the distribution and transport of tritium in the North Pacific. First, the observed tritium in precipitation dataset of GNIP/ISOHIS is chosen, and used to develop an input function of tritium for the model domain from 1951 to 1997 in terms of the triangulation for interpolation. Then, the input function is used as an upper flux for the tritium model. The OGCM with tritium is integrated for 47 years with the initial condition of zero tritium concentrations. Compared with the observations from GEOSECS and WOCE, the model generates a meridional gradient of surface tritium concentrations and the high tritium concentrations in the subsurface layer, which is consistent with that indicated in the observations. The simulated time series of total tritium fluxes from the atmosphere to the ocean shows a spike in 1963. The total inventory of tritium in the ocean changes slowly with time after 1975. Tritium enters the higher-latitude region, and then is mainly transported by the subsurface process towards the equatorial region, which is well simulated in the model. However, the difference mainly occurs at 30°N–40°N, which can be seen also in the simulation of CFCs. This difference may partly originate from the insufficient description of physical processes in the OGCM. Nevertheless, some uncertainties exist in the development of the tritium input function, which can also influence the simulated results.

关键词： North Pacific basin-wide ocean general circulation model tritium input function tritium distributions

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),{2., china 2.state key laboratory of Numerical Modeling for atmospheric sciences and Geophysical Fluid Dynamics (lasg), institute of At-mospheric physics, CAS,{2., china Nansen-Zhu International Research Center (NZC) Institute of Atmospheric Physics Chinese Academy of Sciences (CAS) Beijing China state key {2. of Numerical Modeling for atmospheric sciences and Geophysical Fluid Dynamics (lasg) Institute of Atmospheric Physics CAS Beijing 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

Nonlinear local Lyapunov exponent and atmospheric predictability research

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Science china Earth sciences 2006年第10期49卷 1111-1120页

作者： CHEN Baohua1, LI Jianping1,2.& DING Ruiqiang2.1. College of atmospheric sciences, Lanzhou University, Lanzhou 730000,{2. 2. state key laboratory of Numerical Modeling for atmospheric Science and Geophysical Fluid Dynamics (lasg), institute of atmospheric physics, chinese academy of sciences, beijing 100029,{2. College of atmospheric sciences Lanzhou University Lanzhou China state key {2. of Numerical Modeling for atmospheric Science and Geophysical Fluid Dynamics (lasg) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China

Because atmosphere itself is a nonlinear system and there exist some problems using the linearized equations to study the initial error growth, in this paper we try to use the error nonlinear growth theory to discuss its evolution, based on which we first put forward a new concept: nonlinear local Lyapunov exponent. It is quite different from the classic Lyapunov exponent because it may characterize the finite time error local average growth and its value depends on the initial condition, initial error, variables, evolution time, temporal and spatial scales. Based on its definition and the at-mospheric features, we provide a reasonable algorithm to the exponent for the experimental data, obtain the atmospheric initial error growth in finite time and gain the maximal prediction time. Lastly, taking 500 hPa height field as example, we discuss the application of the nonlinear local Lyapunov exponent in the study of atmospheric predictability and get some reliable results: atmospheric predictability has a distinct spatial structure. Overall, predictability shows a zonal distribution. Prediction time achieves the maximum over tropics, the second near the regions of Antarctic, it is also longer next to the Arctic and in subtropics and the mid-latitude the predictability is lowest. Particularly speaking, the average prediction time near the equation is 12.days and the maximum is located in the tropical Indian, Indonesia and the neighborhood, tropical eastern Pacific Ocean, on these regions the prediction time is about two weeks. Antarctic has a higher predictability than the neighboring latitudes and the prediction time is about 9 days. This feature is more obvious on Southern Hemispheric summer. In Arctic, the predictability is also higher than the one over mid-high latitudes but it is not pronounced as in Antarctic. Mid-high latitude of both Hemispheres (30°S―60°S, 30°―60°N) have the lowest predictability and the mean prediction time is just 3―4 d. In addition, predictab

关键词： nonlinear, local, Lyapunov exponent, atmospheric predictability, maximal prediction time.

THE RESPONSES OF THE THIRD GENERATION OF IAP/lasg OCEANIC GCM TO DIFFERENT EXTERNAL FORCING

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Journal of Hydrodynamics 2001年第3期13卷 107-114页

作者： Li Wei, Liu Hai long, Zhang Xue hong lasg institute of atmospheric physics,{2., beijing 100029, china Fang Guo hong institute of Oceanology,{2., Qingdao 2.6071, china key laboratory of Marine Scienc lasg Inst. of atmospheric {2. Chinese Acad. of Sci. Beijing 100029 China

Forced by different wind stress as well as different surface heat flux, three 10 year integrations using L30T63 oceanic GCM are carried out. The annual mean state, seasonal cycle and interannual variability of the upper ocean temperature over the tropical Pacific are examined. In the case of annual mean state of sea surface temperature, relults from D15c and D15e are alike and have good agreement with NCEP data. Defects in D15d include the excessively higher SST over warm pool region and higher SST along the eastern coast. The corresponding westward displacement of cold water is also noticeable. All the experiments represent the annual cycle of SST in the eastern equatorial Pacific while the amplitudes are weaker compared to NCEP data. The intensity of interannual variability of SST in eastern equatorial Pacific is markedly improved D15d and is perfectly comparative with that from NCEP data. The eastward propagations of the interannual variability of upper ocean heat content along the equator in 1982.1983 E1 Nio are well represented in all experiments. On the onset stage of 1982.1983 E1 Nio, the modeled interannual variabilities of SST and heat content are generally the same among all experiments. It is the weakest interannual variability of surface heat flux, which damps SST variability during the mature phase of E1 Nio, that results in a most intensified SST variability in D15d.

关键词： Oceanic GCM tropical pacific SST

Optimality of a nonlinear stability criterion of two-layer Phillips model

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chinese Science Bulletin 1998年第8期43卷 656-659页

作者： MU Mu state key {2. of Numerical Modelling for atmospheric sciences and Geophysical Fluid Dynamics, institute of atmospheric physics, chinese academy of sciences, beijing 100029, china state key {2. of Numerical Modelling for atmospheric sciences and Geophysical Fluid Dynamics. institute of atmospheric physics Chinese Academy of Sciences Beijing China

The optimality of a nonlinear stability criterion of motions of two_layer Phillips model is investigated. The result shows that for a given zonal periodical channel, there exist cases that there is no normal mode which grows exponentially even if the sufficient conditions of the criterion are destroyed. On the other hand, the above criterion is optimal in the following sense: when the sufficient conditions of the criterion are destroyed, except some critical cases, there exists a finite zonal periodical channel, in which there is a zonal normal mode growing exponentially.

关键词： Phillips model nonlinearity stability.

On the parameterization scheme of gravity wave drag effect on the mean zonal flow of mesosphere

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chinese Science Bulletin 2003年第10期48卷 1020-1023页

作者： GAO Shouting & RAN Lingkun state key {2. of Atmosphere physics and Chemistry (LAPC), institute of atmospheric physics, chinese academy of sciences, beijing 100029, china state key {2. of Atmosphere physics and Chemistry (LAPC) Institute of Atmospheric Physics Chinese Academy of Sciences China

Based on McFarlane抯 parameterization scheme of gravity wave drag, a refined gravity-wave-drag scheme is presented. Both the drag effect of the momentum flux and the dissipation effect of gravity wave breaking on the mean zonal flow are included in the refined parameterization scheme. The dissipation effect can be formulated with the gravity wave numbers and the mean quantities. The refined parameterization scheme may represent a complete drag effect of stationary gravity wave breaking on the mean zonal flow.

关键词：参数化法重力波阻纬向气流中间层大气动力学

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 2.0030,{2. 2.3} key laboratory of Numerical Modeling for atmospheric sciences and Geophysical Fluid Dynamics(lasg),institute of atmospheric physics,{12. academy of sciences,beijing 100029,{2. Shanghai Typhoon institute of china Meteorological Administration state key {2. of Numerical Modeling for atmospheric sciences and Geophysical Fluid Dynamics (lasg) Institute of Atmospheric Physics Chinese Academy of Sciences

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

Computational properties of a new horizontal staggered grid

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Science china Earth sciences 2005年第9期48卷 1559-1568页

作者： LIU Yudistate key {2. 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 2.1101, china state key {2. of Numerical Modeling for atmospheric sciences and Geophysical Fluid Dynamics Institute of Atmospheric Ph Chinese Academy of Sciences Beijing China institute of Meteorology PLA University of Science and Technology Nanjing China

This paper presents a new horizontal staggered grid (LE grid), which defines h at a gridpoint, and both u and v at the same mid-gridpoint along the x and y directions. A general method is used to deduce the dispersion relationships of describing inertia gravity waves on LE grid and Arakawa A―E grids, which are then compared with the analytical solution (AS) in re- solved or under-resolved cases, using two-order central difference or four-order compact differ- ence scheme from the frequency and group velocity. Results show that in both resolved and under-resolved cases, no matter whether two-order central difference or four-order compact dif- ference scheme is used, the frequency and group velocity discrete errors on LE grid in describing inertia gravity waves are smaller than those of Arakawa A―E grids. At the same time, it is only on LE or Arakawa grid C that the employment of a compact difference scheme of higher difference precision can improve their accuracy in describing inertia gravity waves. However, as for the other four grids (Arakawa A,B,D and E), when the difference precision increases, the accuracy of simulating inertia gravity waves decreases.

关键词： horizontal staggered grid, inertia gravity wave, LE grid, Arakawa A-E grid, compact difference scheme, central difference.