Assimilation of Satellite Altimetry into a Western North Pacific Operational Model

l. IntroductionLinear dynamics ls domlnant as a response to atmospheric forcing in the equatrialregion. In the mid-- to high--latitudes, ocean represents nonlinear phenomena such as strongcurrents and meso--scale eddies. Heat and water fluxes are also important. The resultantscales of the phenomena are rather small. We developed, for the mid-- to high--latitudes, anocean data assimilation system COMPASS--K: Comprehensive Ocean ModeIing, Prediction,Analysis and Synthesis System in the K…     

The Seasonal Climate and Low Frequency Oscillation in the Simulated Mid-Holocene Megathermal Climate

l.IntroductionThegoalofPMIP(PaleoclimateModellingIntercomparisonProject)istocomparethestate-ofthe-artclimatemodels'simulationsforthepastclimateonthebasisofthepaleoclimatedata.Oneofthemostinterestingperiodsisthemid-Holoceneduring8.5-3.OkaBPwiththemaximumin7.2-6.OkaBP(beforepresent)inChina(Shietal.,l992).Itwasre-vealedthatthetemPeraturewasl-4'Chigherandtheprecipitationwas4O%-loO%largercomparedtothepresentoverChina(Shietal.,l992;Anetal..l99l;Kongetal.,l99O,l99l).Therehavebeensomesimula…     

The 1997/ 98 enso cycle and its impact on summer climate anomalies in east asia

l.IntroductionTheENSOeventcanbeconsideredasthemostimp0rtantphenomenonoftheair-seainteractionintheequatoria1Pacific.WhenanENSOeventoccursintheequatorialPacific,severeclimateanomalieswillbecausedinmanyregionsoftheworld(Namias,l976;HorelandWallace,l98l;RasmussonandCarpenter,l982;RasmussonandWallace,l983).Similar-ly,theENS0eventalsohasalargeimpactonclimateanomaliesinEastAsia(WangandZhu,l986;FuandYe,l988).lnrespectoftheimpactofENSOeventonclimateanomaliesinChina,theinvestigationofHuanga…     

Dynamic features and maintenance mechanism of asian summer monsoon subsystem

l.Intr0ducti0nInitially,monsoonwasreferredtotheseasonalreversal0fwinddirectionovertheIndian0cean,especiallyalongthecoastalbeltoftheArabianSea(Webster,l987).Withthein-creasedunderstandingofmonsoonbehavi0rs,itsdefinitionandimplicationhavebeenaug-mentCd.BasedonpreviousstudiesandwindveeringinJanuaryandJulyasthecritCri0nofitsdefinition,Ramage(l97l)showedthatthemonsoonregionincludesAsiantropics/subtropics,Australia,Africaandtheiradjacentseas.Withadvancesinmonsoonre-search,metCorologistshaveexp…     

Influence of enso event on the maintenance of pacific storm track in the northern winter

l.Intr0ductionItiswellkn0wnthatthereisanobviousinteractionbetweencirculationsin-andextra-tropics,whichusuallyexhibitsauniquefeatureduringENSOPeriod(Bjerknes,l969;Huang,l99l;H0skinsandKaroly,l98l;HorelandWallace,l981famongothers).There-searchrevealsthataneddyfluxcausedbyatransientdisturbanceinthemiddlelatitudedur-ingthePeriodofENSOeventplaysanimPOrtantroleinthemaintenanceofanomalousat-mosphericcirculationpattern,triggeredbyseasurfacetemPeratureanomalyatequator,inthePacificOceanandtheNor…     

Modeling N_2O Emissions from Agricultural Fields in Southeast China

l.Intr0ductionWiththedevelopmentofeconomy,theenvironmentalproblemsarebec0mingincreasinglyserious.Am0ngthem,theenhancementofgreenh0useeffectsandglobalwarm-ingaretwoimPOrtantonesthathavear0usedwideattention.Nitrousoxide(N,O)isanim-POrtantgreenhousegasandplayingagreatroleinthesetwoprocesses.SincetheIndustrialRevolution,theatmosphericN2Oconcentrationhasincreasedbyaboutl5%(IPCC,l995).Inthelast4Oyears,itincreasedrapidlyatarateof0.2%ro.3%yr-'(IPCC,l99O).Ifitin-creasesatthisrate,theatmospheri…     

On the upper oceanic heat budget in the south china sea:Annual cycle

l.Intr0ducti0nInrecentyCarstheSouthChinaSea(SCS)hasbecomeoneofthemostimP0rtantregionsinthelocalair-seainteractionresearchbecauseofitssPecialgeographicPOsitionandsemi-encloseddeepbasincharacteristics.TheimP0rtanceoftheSCSisembodiedmainlyinwhichisoneofthekeyheatandmoisturesourcesofatmosphericcirculationineasternAsia.TheonsetandmaintenanceoftheSCSmonsoonarecloselyconnectedwiththelargeheattransportfromtheSCStoair(Yan,l997).Thestudyonspatial-temporalvariationofair-seaheatexchangeintheSCS…     

An OGCM Simulation of Seasonal and Interannual Variabilities in the Surface-Layer Pacific of the Equatorial Band

l. IntroductionThe physical mechanisms contro1ling t]de El Nifio event have been studied based on ob-servations in the equatorial Pacific (Weare l983; Reed l986; Hayes et al. l99l; McPhadenand Picaut l990; Frankignoul et al. 1996; Weisberg and Wang l997). One of the most impor-tant issues is whether the surface heat flux ojr ocean advective heat fluxes are dominant in con-trolling the sea surface temperature (SST). Some studies indicated that the SST is mainly con-trolled by the surface…     

A Coupled Dynamical-Radiational Model of Stratocumulus

A model dealing with interactions between the air and low stratiform clouds is presented based on the mixed-layer model Lilly (1968) pioneered and on Deardorffs three dimensional numerical model results. Its main new aspects lie in 1) consideration of the natures of both the atmosphere and cloud; 2) a new entrainment velocity scheme with few arbitrary assumptions; 3) transition from one-mixed layer to two-mixed layer model; and 4) parameterization of radiation and precipitation calculations.The model results for radiation, moisture, and heat turbulent fluxes turn out to be in good agreement with those calculated or observed by Kawa (1988), Nicholls (1984), and Schmets et al. (1981) in California, the North Sea, and the North Atlantic, respectively.Basically, this paper furnishes the theoretical basis for a model to address questions concerning the time-evolution of thermodynamical profiles both in cloud and out of cloud. The applications of this model wil be in a separate paper.     

Response of IAP/ LASG GOALS model to the coupling of air-Sea fresh water exchange

l.IntroductionWaterPervadesallofthephysicalanddynamicstructureswithintheEarthclimatesys-temthroughamyriadofhydrologicalprocesses.Thehydrologicalcycleinfluencesclimateinavarietyofways,andthereexistsrobustwaterfluxexchangebetweenoceanandatmosphere(Zhouetal.,l999).Theexchangeoffreshwaterbetweenatmosphereandoceanthroughtheair-seainterfaceisoneoftheleastelementsunderstood,butnowisconsideredasoneofthemostimportantelementsoftheclimatesystem,esPeciallyforoceancirculationchangesondecadaltomillennialt…     

The impact of nonlinear stability and instability on the validity of the tangent linear model

l.Intr0ducti0nTheequationsgoverningthemotionsoftheatmosphereandoceanaren0nlinear0nes.Itisdiffcultandcomplicatedtodealwiththenonlinearproblem.Sothetangentlinearmodel(TLM),whichisobtainedbylinearizingthenonlinearmodelinthevicinityofthebasicflow.iswidelyutilizedinthetheoreticalresearchandpracticalimplementationintheatmosphericandoceanicsciences.First-TLMcanbeusedtoestimatetheev0luti0nofsmallPerturbati0nsinaf0recastmodel.Second,itisadoptedinextendedKalmanfilterinthedataassimilation(Evensen,l99…     

Baroclinic Instability in the Generalized Phillips’ Model Part I: Two-layer Model

By employing Arnol’d’s method (energy-Casimir), this paper has studied the nonlinear stability of the two-layer generalized Phillips’ model for which the top and bottom surfaces are either rigid or free, and obtained some nonlinear stability criteria. In addition, some linear stability criteria are obtained by normal mode method. The re-sults reveal the influences of the free surface parameter on the stability of atmospheric and oceanic motions     

2005年10月亚洲地区逐日500hPa西风环流指数及副热带高压脊线(120°E、130°E、140°E)位置

产，‘、d产碑一‘J刀产了二了、.r，. 日 1 2 3 压 5 陌 厅 8 阿 l0 ll l2 13 I4 l5 网 阿 网 国 同 同 国 蔺 同 冈 同 同 同 国 同 3I 数 299 277 236 260 289 315 360 340 330 261 250 289 289 396 370 404 468 482 447 469 518 476 361 3 11 286 303 306 265 320 322 374 120OE 30 3O 25 24 24 25 25 25 25 24 29 24 23 (21) 21 22 22 22 22 22 加 20 l9 l8 l5 17 19 l8 (19: 同 l9 130OE 30 30 27 28 28 27 27 25 25 27 Z (30二 / / / 2l 21 22 22 2I 2O 19 l9 l8 I6 l9 20 l9 (19) l9 】9 140OE 冈 画 网 28 阿 28 28 26 26 冈…     

Baroclinic Instability in the Generalized Phillips’ Model Part II: Three-layer Model

The nonlinear stability of the three-layer generalized Phillips model, for which the velocity in each layer is constant and the top and bottom surfaces are either rigid or free, is studied by employing Arnol’d’s variational principle and a prior estimate method. The nonlinear stability criteria are established. For com-parison, the linear instability criteria are also obtained by using normal mode method, and the influences of the free parameter, β parameter and curvature in vertical profile of the horizontal velocity on the linear in-stability are discussed by use of the growth rate curves.The comparison between the nonlinear stability criterion and the linear one is made. It is shown that in some cases the two criteria are exactly the same in form, but in other cases, they are different. This phenom-enon, which reveals the nonlinear property of the linear instability features, is explained by the explosive resonant interaction (ERI). When there exists the ERI, i.e., the nonlinear mechanisms play a leading role in the dynamical system, the nonlinear stability criterion is different from the linear one; on the other hand, when there does not exist the ERI, the nonlinear stability criterion is the same as the linear one in form.     

An Online Model Correction Method Based on an Inverse Problem:PartⅡ——Systematic Model Error Correction

An online systematic error correction is presented and examined as a technique to improve the accuracy of real-time numerical weather prediction, based on the dataset of model errors(MEs) in past intervals. Given the analyses, the ME in each interval(6 h) between two analyses can be iteratively obtained by introducing an unknown tendency term into the prediction equation, shown in Part I of this two-paper series. In this part, after analyzing the 5-year(2001–2005) GRAPESGFS(Global Forecast System of the Global and Regional Assimilation and Prediction System) error patterns and evolution,a systematic model error correction is given based on the least-squares approach by firstly using the past MEs. To test the correction, we applied the approach in GRAPES-GFS for July 2009 and January 2010. The datasets associated with the initial condition and SST used in this study were based on NCEP(National Centers for Environmental Prediction) FNL(final) data.The results indicated that the Northern Hemispheric systematically underestimated equator-to-pole geopotential gradient and westerly wind of GRAPES-GFS were largely enhanced, and the biases of temperature and wind in the tropics were strongly reduced. Therefore, the correction results in a more skillful forecast with lower mean bias and root-mean-square error and higher anomaly correlation coefficient.     

A Simple Quasi-Geostrophic Coupled Ocean-Atmosphere Model

The quasi-geostrophic atmospheric and oceanic equations of momentum and thermodynamics with dissipation factors are used to create a simple coupled ocean-atmosphere model describing the large-scale shallow-water motion. We discuss the ocean-atmosphere coupling effect in mid-high and low latitudes separately and analyze characteristics of which the oscillatory periods of coupled low-frequency modes (ocean mode) vary with the coupling frequency and latitudinal number. This can interpret the correlation between low-frequency oscillation and ocean-atmosphere interaction. Then from the dispersion curves of atmosphere and ocean, we reveal effect of the coupling strength on the propagation of Rossby waves. The convection mechanism between the two modes is also discussed in view of the slowly varying wave train.The results show that Newtonian cooling and Rayleigh friction play a stable rule in oceanic Rossby waves, the period of coupled low-frequency mode grows with the increment of the coupling frequency. The     

Energy and Water Balance at Soil-Air Interface in a Sahelian Region

l. IntroductionModel simulation of soll physical properties is very 1mportant for climate studies becauseof the role they play in different interaction processes with the atmosphere. One of the mostwidespread studies is the implementation of soil models 1n General Circulation Models(GCMs); previous studies showed, in fact, that climate simulat1ons are sensitive to theparameterization of the energy and mass fluxes at the land surface (V1terbo, l995; Beljiaars etal., l996; Dolman et al., l997…     

What Kind of Initial Errors Cause the Severest Prediction Uncertainty of El Nino in Zebiak-Cane Model

With the Zebiak-Cane(ZC)model,the initial error that has the largest effect on ENSO prediction is explored by conditional nonlinear optimal perturbation(CNOP).The results demonstrate that CNOP-type errors cause the largest prediction error of ENSO in the ZC model.By analyzing the behavior of CNOP- type errors,we find that for the normal states and the relatively weak El Nino events in the ZC model,the predictions tend to yield false alarms due to the uncertainties caused by CNOP.For the relatively strong El Nino events,the ZC model largely underestimates their intensities.Also,our results suggest that the error growth of El Nino in the ZC model depends on the phases of both the annual cycle and ENSO.The condition during northern spring and summer is most favorable for the error growth.The ENSO prediction bestriding these two seasons may be the most diffcult.A linear singular vector(LSV)approach is also used to estimate the error growth of ENSO,but it underestimates the prediction uncertainties of ENSO in the ZC model.This result indicates that the different initial errors cause different amplitudes of prediction errors though they have same magnitudes.CNOP yields the severest prediction uncertainty.That is to say,the prediction skill of ENSO is closely related to the types of initial error.This finding illustrates a theoretical basis of data assimilation.It is expected that a data assimilation method can filter the initial errors related to CNOP and improve the ENSO forecast skill.     

An Elegant Coupled Model

This paper deals with a new family of coupled wave equations which are basically nonlinear in nature. An analytical study enables us to show that these equations exhibit solitary wave profiles. Finally some remarks are drawn from the standpoint of atmospheric problem.     

资料

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