1996 Vol. 10 No. 3
Cover Note
1996, 10(3): 257-269.
Abstract：Systematic errors in the COLA R15 AGCM are analyzed by the SVD technique.In order to remove or reduce this kind of error source and reduce climate drift in coupled runs a way in which the wind stress anomalies simulated by an AGCM are reconstructed is proposed by using SVD analsis.Experimental results show that not only wind stress anomalies simulated by an AGCM are obviously improved by reconstructed wind stress anomalies but also this reconstruction has a function of a low-pass time filter,as a result,response of the ZC ocean model to reconstructed wind stress anomalies is more realistic than that of simulated wind stress anomalies by an AGCM.In this paper,application of the hybrid couple ocean-atmosphere model is further discussed.More+
Abstract：A zonal domain primitive equation modeling system(ZDMS) is used to study the effects of the initial heating anomalies over the Tibetan Plateau and the western Pacific on the East Asian and the Chinese summer climate,the relative importance and the mechanisms are discussed.Results show that in spite of the different locations of the heating anomalies the influences of the two anomalyareas are much similar to each other when the scaling of the two areas is the same.The two areas of heating anomalies have their own affecting domains in which one is more important than the other.In the western Pacific the heating anomaly over the western Pacific is more evident and in the Tibetan Plateau area the heating anomaly over the Tibetan Plateau is more obvious.For the east part of China the effects of the two heating anomalies both exist and almost have the equal importance.The initial anomaly of the sea surface temperature(SST) over the western Pacific can be kept during the entire time integration while in the Tibetan Plateau it can not be maintained.More+
Abstract：An experimental work on the transplant of high resolution limited area model(HIRLAM) isfirstly introduced into China.For the implementation,first of all is to adjust a new geographicalcoordination and to remove the instability caused by the Tibetan Plateau,the roof of the world.Then,we have applied this model to simulate a flood-making torrential rain process which occurredin the Changjiang-Huaihe River Valley in July 1991.That revealed the formation,development andmovement of a mesoseale heavy rain system which had made a disastrous flood event in the middleand lower reaches of Changjiang River Valley.The result encourages us to use the HIRLAM for the researches on the Meiyu belt,the salientfeature of precipitation of East Asia,and the numerical prediction of heavy rains in China.More+
1996, 10(3): 295-308.
Abstract：The limited area analysis and forecast system(LAFS) was developed and has been put into operational use at National Meteorological Center since January 1991.This system can be regarded as a branch system attached to the global assimilation and medium-range forecast system which is based on a spectral model T42L9.The main advancements as an upgrade operational system are as follows:the use of a regional fine mesh optimum interpolation(OI) analysis scheme:the realization of the nonlinear normal mode initialization for the regional model:the development of a 15L-spherical grid primitive equation model(with real topography and enstrophy conservation) and its nesting forecast with the spectral model T42L9.More+
Abstract：The interaction between anomalous winter monsoon in East Asia and El Nino is further studied in this paper.The new results still more proved a previous conclusion:there are clear interactions between El Nino and winter monsoon in East Asia.The continual westerly burst andstronger cumulus convection over the equatorial central-western Pacific caused by stronger wintermonsoon in East Asia can respectively excite anomalous oceanic Kelvin wave and stronger atmospheric intraseasonal oscillation in the tropics,then excite the El Nino event through air-sea interction.In El Nino winter,there are warmer and weaker winter monsoons in East Asia.The El Nino will still reduce the intensity of intraseasonal oscillation and leads it to be barotropic structure.More+
1996, 10(3): 321-330.
Abstract：A one-dimensional cumulus cloud chemistry model(ICCCM) is developed to simulate cloud physical processes and chemical processes during the evolution of a convective cloud.The cloud physical submodel includes a detailed microphysical parameterized scheme of 20 processes.The chemistry submodel is composed of three parts:gas phase chemistry,aqueous phase chemistry and scavenging of soluble gases.The gas phase reaction mechanism contains 85 reactions among 45 species including 13 organics.The aqueous phase reaction mechanism contains 54 reactions among 40 species and 12 ion equilibria.Mass of 19 gases is transported between the gas phase and the aqueous phase.With this model,studies may be made to analyze the interactions among processes during lifetime of a cumulus cloud.More+
Abstract：Clear air turbulence(CAT).a meso-or microscale(subgrid scale) phenomenon occurring insynoptic scale flow field at high altitude,is very difficult to be observed by the conventional observation network.Thus it is necessary to approach an index to predict CAT.But at first,the structure characteristics of CAT should be preanalyzed.In this paper,based on the theoretical and diag-nostic analysis of a case,features for wind profile,energy budget and dynamic mechanism of thiscase were presented.Furthermore,an objective and quantitative index for CAT forecast was given.The verification for its efficiency was done with both realtime observation data and productsfrom a numerical model.The results are very encouraging.More+
Abstract：It is possible to understand the lightning activities in a specific region and compare test results of different apparatus only when a reliable evaluation of detection efficiency distribution pertaining to a particular lightning location system(LLS) is available.Based on the data in 1992.an approximate evaluation of detection efficiency spatial distribution for single-station lightning location system(M-LDARS) and LLP three-station lightning location system in Beijing-Tianjin-Hebei area is presented in the paper,showing that the average detection efficiencies are smaller than 48% and 46% respectively.In addition,the article offers an evaluation of spatial distribution of ground stroke density(Dg) and positive stroke percentage,indicating that six high stroke density zones exist along the southeastern sides of the Taihang and Yan-shan Mountains.The stroke density of mountainous region is higher than that of the plain region,in contrast to the case of positive stroke percentage.Also,it is shown that within a radius of 250km,the average of Dg is 1.2(km-2 a-1) while the average positive stroke percentage is 10.9%.Finally,the paper proposes a possible test method of accurately evaluating the spatial distribution of detection efficiency(A).More+
Abstract：The water deficits in different development stages and the whole growing season of winter wheat in North China under climate change scenarios are analyzed based on the meteorological data,crop phenomenon and soil hydrological data of 30 weather stations.The results show that if the temperature rises,the potential evapotranspiration and crop maximum transpiration will in-crease 8%-10%;the actual evapotranspiration in whole growing season will increase about 1%-2%;and it seems to decrease in spring.The refore the water deficit status would deteriorate.Theamount of water deficit in whole growing season would increase 14%-30%,and the water deficit isolines might shift southward with maximum shift distance being 190 km.As a result the climatic suitability of winter wheat would change,and the variation rate of yield reduction will be 8%-20% of the present value which results in the declining output values.The irrigation amount would increase 25%-33%,and the agriculture cost might increase owing to additional irrigation.More+
1996, 10(3): 367-375.
Abstract：The precipitation is a primary element which directly affects the agricultural production of the country with one fifth of the world population.With the economic development the water resource stress is getting greater.In this paper,based on the data at 162 stations selected evenly over China from 1960 to 1991 the stability and potential predictability of annual precipitation have been studied.The eastern and southern parts of the country having abundant precipitation enjoy more stable precipitation.The north and northwest parts of the country where the precipitations are deficient have unstable precipitations.The potential predictability approximates to the ratio of the estimated interannual variance to the climatic noise.Generally the annual precipitation over China is potentially predictable.In the area between the Huanghe River and Changjiang River and the east of northeastern China the potential predictability is the lowest in the country.In the north and northwest of the country the potential predictability is greater.The southeastern coast has relatively low values of potential predictability.Also,the method of estimating climatic noise of annual precipitation has been discussed from the idea of Yamamoto et al.(1985) in order to estimate the potential predictability.More+
1996, 10(3): 376-384.
Abstract：To estimate sea surface temperature(SST) with high accuracy from radiometrie measurements,it is no longer acceptable to assume that sea surface emissivity is unity or any other constant.This note presents an investigation of the desirable emissivity accuracy in relation to retrieval.It was found that 1% error in surface emissivity can cause up to 0.7 K error in the retrieved SST,although this sensitivity is often reduced to about 0.5 K on average because of the downward atmospheric radiation at surface partially compensates for the emissivity error.Since the downward atmospheric radiation ratio is controlled to a large extent by the integrated water vapor in the atmosphere and,secondarily,by view angle,the sensitivity of SST retrieval to surface emissivity has been computed as a function of these two parameters.More+
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