Vol.13, NO.6, 2002

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IMPACTOF HETEROGENEOUS LAND SURFACEON MODELS AND ITS PRELIMINARY PARAMETERIZATION
Zhang Zhengqiu, Zhou Xiuji, Li Weiliang
2002, 13(6): 641-649.
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Abstract:

To improve the parameterization of land surface processes, a preliminary analysis of the impact of subgrid land surface heterogeneity on model results is carried out. The scheme of land surface process parameterization is presented by using an averaging method. The impact of heterogeneity is discussed. Numerical results show that the heterogeneity could lead a discrepancy between model results and reality, and the averaging method can be applied to the heterogeneous land surface
A STUDY OF RELATIONSHIPS BETWEEN SPRING WINTER AND SUMMER GENERAL CIRCULATION ANOMALIES
Sun Li, An Gang
2002, 13(6): 650-661.
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Abstract:
By using Singular Value Decomposition (SVD) technique and monthly mean 500 hPa height data in the Northern Hemisphere from 1951 to 2000, the inter-seasonal relationships of general circulation anomalies are studied. The results show that the first mode derived from SVD indicates the key coupled characteristics-there exists close temporal and spatial correlation between seasonal 500 hPa height anomalies and its former seasonal 500 hPa height anomalies. Especially there are obvious connections between the general circulation anomalies in summer and those in past winter and spring. The variations of the East Asian trough, North American trough, polar low, North Pacific oscillation and Siberian high of the North Hemisphere 500 hPa in winter and spring play important roles in the general circulation anomalies in the following summer and autumn in East Asian.
DIAGNOSTIC ANALYSIS OF MOIST POTENTIAL VORTICITY ANOMALY IN TORRENTIAL RAIN SYSTEMS
Gao Shouting, Lei Ting, Zhou Yushu,
2002, 13(6): 662-670.
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Abstract:
The moist potential vorticity (MPV) equation with both heat and mass forcing is derived. It is clarified that both heat and mass forcing induced by the intensive precipitation in torrential rain systems can lead to moist potential vorticity anomaly. With NCEP/NCAR 1°×1° data, the moist potential vorticity anomaly is diagnosed along the Yangtze River from June 23 to June 26 1999. The results indicate that moist potential vorticity anomaly occurs between 700 hPa and 500 hPa, and the maximum anomaly value is up to 1.4 PVU. Both dynamical and diagnostic methods reveal that moist potential vorticity anomaly regions correspond well to the regions of intensive precipitation.
ANALYSIS OF RELATION OF SOUTH ASIA HIGH AND RAINSTORM CAUSED BY NORTHWESTERLY UPPER-LEVEL JET
Ding Zhiying, Zhang Xingqiang, Shou Shaowen
2002, 13(6): 671-679.
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Abstract:
Using MM4 model, the process of rainstorm is molded in the period from 08:00 BLT July 21 to 08:00 BLT July 22, 1998. It is found that the convergence and divergence field of the South Asia High and the northwesterly upper-level jet form a couple of mesoscale direct circulation and counter-circulation. The circulation pattern keeps the rainfall maintaining and strengthening. The sinking of the high potential vorticity is related to the lower vortex and the rainfall increasing. The conditional convective instability in the later period is more obvious for the effect of rainstorm than conditional symmetric instability.
CAUSALITY ANALYSIS OF A HEAVY RAIN PROCESS OVER MIDDLE AND LOWER REACHES OF CHANGJIANG RIVER IN JUNE 1998
Yan Zhihui, Tian Hua
2002, 13(6): 680-687.
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Abstract:
A numerical experiment on a heavy rain process occurred in the last dekad of June in 1998 is conducted by means of the limited area prediction model of the National Meteorological Center. The formation causes of the process are discussed through analyzing the winds, water vapor, vertical velocity and other elements. The results show that the main synoptic scale weather systems causing the heavy rain are the Southwest low-level jet and a shear line between dry air from north and warm and moist air from /southwest in the middle and lower reaches of the Changjiang River. The mesoscale weather systems moving along the shear line play a very important role in precipitation reinforcement
A COUPLED OCEAN-ATMOSPHERE MODEL WITH A HIGHER RESOLUTION OCEANIC COMPONENT
Zhang Tao, Guo Yufu, Wu Guoxiong
2002, 13(6): 688-695.
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Abstract:
A new version of the IAP/LASG Global Ocean-Atmosphere-Land System (GOALS) model (called GOALS-5) with a higher resolution Oceanic General Circulation Model (OGCM) component is developed. GOALS-5 has been integrated successfully for 30 years without climate drift. The SST simulated by GOALS-5 in mid-and high-latitudes for the Northern Hemisphere summer is greatly improved in contrast with the results simulated by several old versions, which is maybe attributed to an enhanced meridional heat transport resulting mainly from the use of GM90 isopycnal mixing scheme. The new model version also has the ability to simulate the warm and cold events over the central and eastern equatorial Pacific. In comparison with the previous versions, the simulated amplitude and location of SST anomaly in the tropical Pacific is ameliorated in the new model
DIAGNOSTIC ANALYSIS OF A CONTINUOUS HEAVY RAIN PROCESS OVER JIANGHUAI AND HANGJIAHU PLAINS USING “NMOCSF”
Guo Keyi, Sheng Wenbin
2002, 13(6): 696-703.
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Abstract:
A continuous heavy rain process at Jianghuai and Hangjiahu Plains is diagnosed with a new method of curved surface fitting (NMOCSF). Some valuable standpoints are presented. Combining with the weather situation, the formation of the quasi-stationary North China high and its contribution to the continuous heavy rain process over Jianghuai and Hangjiahu plains are discussed. It is pointed out that special attention should be given to the intensity and the position of the quasi-stationary North China high during the Meiyu season around Jianghuai and Hangjiahu plains. Once the block-up feature forms, a continuous heavy rain process will probably takes place in a large area.
EFFECTS OF NORTH PACIFICWINTER BLOCKING HIGH ON WESTWARD ROUTES OF SHIPS
Yin Jinyong, Du Bingyu, Li Zechun, Qi Guiying
2002, 13(6): 704-710.
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Abstract:
The synoptic situations are analyzed, by using ten year data, of the construction, maintenance and disintegration of the North Pacific winter blocking high, combined with theories of meteorological ship navigation guide, meteorological ocean route selecting technology and the factors that affects ocean route selection. It is pointed out that the block high patterns are favorable to the navigation on the high-latitude winter westward route in the North Pacific.
ANTARCTIC SEA-ICE OSCILLATION AND ITS RELATIONSHIP WITH ENSO
Cheng Yanjie, Bian Lingen, Lu Longhua
2002, 13(6): 711-717.
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Abstract:
Antarctic Sea-ice oscillation and its relationship with indices of the atmospheric circulation of the Southern Hemisphere are examined by using 30 year Antarctic sea-ice concentration and NCEP data from January 1968 to December 1997 based on the EOF and SVD methods. A out-phase relationship is found between Ross Sea and Bellingshausen Sea, whose characteristics of the variation is defined as Antarctic Sea-ice Oscillation. Its index (ASOI) has a high correlation with SOI and Nino 3 Index when it is two months ahead of them. The high index and low index composite figures reveal the completely reverse patterns of SAT, SLP, and wind circulation in the Southern Ocean for the two extreme states. The sea-ice anomalies of the two key regions accompany with the opposite wind circulation which may influence the currents of the Southern Pacific ocean and the development of E1 Nino/La Nina events. This evidence indicates a possible ENSO signal between Ross sea and Bellingshausen sea.
STUDY OF INTERDECADAL INTERANNUAL VARIATION OF RAINFALL OVER MID-LOWER REACHES OF CHANGJIANG RIVER AND ITS MECHANISM
Li Feng, He Lifu
2002, 13(6): 718-726.
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Abstract:
Based on the NOAA/NCEP reanalyzed data, SST from the England National Meteorological Bureau, and precipitation data and Subtropical West Pacific High parameters from the National Meteorological Center, the interactions of East-Asian summer monsoon with Mid-east Pacific SSTA are analyzed. The interactions display an inter-decadal variation feature. It is found that the East Asian meridional cell is coupled closely with the low-latitude zonal cell after 1976, which strengthens the association between East-Asian summer monsoon and Mid-east Pacific SSTA. The previous winter SSTA over the Mid-east Pacific affects the offsea SSTA in next summer, as heat sources enforce the Subtropical West Pacific High; as a result, the rainfall over the Mid-lower reaches of the Changjiang River in summer is abundant
NUMERICAL EXPERIMENTON EFFECTS OF REAL SEA SURFACE TEMPERATURE ON DYNAMIC EXTENDED (MONTHLY)FORECASTING
Luo Meixia, Zhang Daomin
2002, 13(6): 727-733.
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Abstract:
The comparative numerical experiments with real and climatic sea surface temperature (SST) for three cases are performed, by using the global spectral model. These cases are on July 10, July 19, 1992 and July 1, 1997, respectively. The effects of real SSTs on the monthly dynamic extended forecast are investigated by the different circulation changes in the general circulation model generated with real and climatic SSTs. The results of numerical experiments show that the effect of real SST on predictions less than 10 days is not obvious, but the impact on monthly forecasts is obvious. The forcing effect of real SST on the monthly forecasts is complex and may be related to the initial conditions of numerical integration, the various physical processes included in the forecast model, and the strength of SST anomalies.
FY-1C VISIBLE CHANNELS' ALBEDO ATTENUATION ANALYSIS AND CORRECTION EXPERIMENT
Gu Songyan, Qiu Hong, Liu Yujie, Fan Tianxi
2002, 13(6): 734-740.
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Abstract:
The remote sensing data of FY-1C visible channels in the Dunhuang test area in two years are used to analyze the channels' albedo attenuation. At the same time, some correction experiments have been conducted. Analysis results show that in most FY-1C channels the instrument functions well in orbit, except in Channel 1. By using a statistic method, a set of new calibration coefficients over time is obtained. There is a good coherence between experiment results and CRCS field observation.
COMPARATIVE ANALYSIS OF AWS-AND MAN-OBSERVED TEMPERATURES
Wang Ying, Liu Xiaoning
2002, 13(6): 741-748.
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Abstract:
With the Development of the Atmospheric Integrat ion Sounding System in China, more and more stations measure meteorological elements by the Automatic Weather Stations (AWS).However, the long-range data w ere obtained from manual observing.Analy sis and evaluation of differences betw een two kinds of data are impo rtant for estimating the impacts of changing inst ruments on measurements and for providing scientific evidences for the continual use of the data after changing instruments.Based on the parallel data of automatic sounding and manual observing in 2000, a comparat ive analysis is made on the validity and continuity of AWS data.The results indicate that generally speaking, departures between AWS and man-made observations are acceptable and their seasonal and regional dif ferences are negligible; owing to the higher sensitivity of AWS data, the departures are larger at sunrise and sunset, as well as at times of maximum and minimum temperature occurring; there is no obvious difference between AWS data and historical sequence.It can be concluded that automatic observat ion can be put to operational use, but needs parallel observing for a certain time, especially in Northwest China and mountain regions.
CHINA OPERATIONAL WEATHER RADAR DATA PROCESSING SYSTEM
Liang Haihe, Zhang Peiyuan, Niu Fang, Hu Shaoping, Zhu Xiaoyan, Ge Runsheng, Xu Baoxiang
2002, 13(6): 749-754.
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Abstract:
According to the technical prescription of the project "National Weather Radar Terminal Updating and Calibration", a national operational weather radar data processing system is developed and performs well. It achieved the format unification of radar data, the manufacture and distribution of products, and the operational function of image redisplay; and advanced radar observation quality, data processing and product application level. In the course of the system design, such factors are considered as the weather radar operational conditions and requirements, the radar detection technological tendency, and the capability and steadiness of the system, as well as advanced algorithms and the open interface. The system appearance is innovative instead of the traditional dialog box and toolbar in the weather radar software.
ADVANCES IN CLIMATE WARMING IMPACT RESEARCH IN CHINA IN RECENT TEN YEARS
Wang Futang
2002, 13(6): 755-766.
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Abstract:
Increasing of greenhouse gas concentration in the atmosphere will strengthen the natural greenhouse effect, which could lead to global climate warming more than other changes. China is large agricultural country with a large of population and relatively deficient farming lands and water resources; thus climate warming is very important to the national economy development. Therefore, the Chinese government and scientists paid great attention to the impact-assessment of climate warming on the national economy in China, especially during the past 10 tears. A brief description is made on major issues of climate warming impact research on the national vegetation, agriculture, forest, water resources, energy use, regional sea level rise in China, etc. As a result, all climate change scenarios derived by GCMs suggest a substantial change in the characteristic natural vegetation types. It is also shown that comparing with the distribution simulated under the normal time period of 1951 to 1980 as the present climate, by 2050 large changes in cropping systems would occur almost everywhere in China. Climate warming would lead to increasing cropping diversification and multiplication. Unfortunately, the possible net balance between precipitation and evapo-transpiration would be negative and the length of growing period would be shorten; therefore, all of these would lead to the reducing grain production in China significantly due to the enhanced moisture stress in soil. The most evident influence of climate warming on water resources would happen in the Huang-Huai-Hai River plain and the water supply-demand deficit would be substantially enhanced in this area. And also, a warmer climate for China will alter the energy demand for domestic heating and cooling, that is, reduce energy use for heating in northern China and increase energy consumption for cooling in southern China. Meanwhile, the projected sea level rise would result in partial submergence of three China's major coastal vulnerable regions, i. e. the Zhujiang River Delta, Changjiang River Delta and Huanghe River Delta.
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