Vol.11, NO.2, 2000

Display Method:
STUDY ON THE CREATION OF DAILY CLIMATIC VARIATION SCENARIOS WITH A STOCHASTIC WEATHER GENERATOR AND VARIOUS INTERPOLATIONS
Wu Jindong, Wang Futang
2000, 11(2): 129-136.
Abstract:
In view of the lower temporal resolution of general circulation models (GCMs) in assessing the impacts of climatic variation, the requirements of climatic variation scenarios and the studies on the potential implication of climatic variation, a stochastic weather generator WGEN is used to produce daily climatic variation scenario which also embodies possible climatic variability in Northeast China in accordance with commonly available information from GCMs. It could be applied to couple with climatic impact models, such as crop growth and development models in order to study the variation of crop growth and development and their yields, and possible impacts of variation of climatic variability.
STUDY ON DROUGHT INDEX OVER THE SOUTHEASTERN CHINA IN SUMMER
Wu Hongbao
2000, 11(2): 137-144.
Abstract:

On the basis of the fact that there exists significant negative correlation between temperature and precipitation over the southeastern China in summer, a drought index is a ppropriately chosen to investigate the spatial and temporal variability of summer drought/flood while no long-lerm trend is found in the time evolution of drought/flood, structures of four spatial patterns based on the index are more signatures of similarity than precipitation patterns, and reflect the climate a nomaly. In addition, singular value decomposition (SVD) is applied to analyze the index dataset and 850 hPa U, V components and some other fields, respectively. It turns out that drought likely occurs in the middle and lower reaches of the Yangtze River when westerly over the South China Sea and the Philippines, southerly over eastern China, and westerly (easterly) over the north (south) of subtropical high increase. On the contrary, flood likely occurs.

IMPACTS OF KUROSHIO SSTA ON STORM TRACK OVER NORTH PACIFIC IN WINTER
Zhu Weijun, Sun Zhaobo
2000, 11(2): 145-153.
Abstract:
Singular value decomposition (SVD) is conducted for 500 hPa filtered potential height variance of 15 storm track regions and the SST over North Pacific in winter. The results show that the second couple of mode obtained from SVD depicts the effect of Kuroshio SSTA on the interannual variability of storm. Furthermore, composite analysis indicates that the SSTA over Kuroshio in winter can give rise to or invigorate WP teleconnection response pattern of 500 hPa height field which, in turn, exerts crucial influence on the interannual variability in vigor and meridianal displacement of the storm track over North Pacific, especially over its central and western parts.
INFLUENCES OF WINTER-STRENGTHEN PATTERN AND WINTER-WEAKEN PATTERN OF EL NIÑO AND LA NIÑA ON DROUGHT/FLOOD IN SUMMER OVER CHINA
Chen Guiying
2000, 11(2): 154-164.
Abstract:
According to the inter-monthly SSTA variation during winter in equatorial East Pacific after the occurrings of El Niño and La Niña onset, the winter-strengthen pattern and winter-weaken pattern of El Niño and La Niña are defined. The characteristics of the general circulation in winter, spring and summer, East Asian monsoon, summer rainfall and the distribution of drought/flood in China are discussed. It is shown that the four kinds of patterns for summer rainfall and drought/flood in China could be associated with different phases of ENSO cycle during winter, and with different responses of the general circulation and East Asian monsoon to that. Finally, a physics concept pattern is proposed about the rainfall distribution patterns in summer over China which are associated with different patterns of El Niño and La Niña in winter as well as the general circulation and the East Asian monsoon.
THE ESTIMATION ON CLIMATE NOISE OF MONTHLY PRECIPITATION IN CHINA
Liu Yanju, Ma Kaiyu, Lin Zhenshan
2000, 11(2): 165-172.
Abstract:
Based on the daily precipitation data of 70 stations selected evenly over China from 1961 to 1991, three estimating methods on climate noise of monthly precipitation are discussed. The climate noises of monthly precipitation in January, April, July and October are estimated by using the improved methods. The results show that with the precipitation increasing, the climate noise of monthly precipitation would increase and has obvious seasonal change. Generally, the value of climate noise is greater in summer than in winter. In spatial distribution, the climate noise in the most areas of China decreases prominently from south to north, and from coastal areas to inland all the year round.
OBSERVATIONAL STUDY ON TOTAL OZONE AMOUNT AND ITS VERTICAL PROFILE OVER LHASA IN THE SUMMER OF 1998
Zheng Xiangdong, Tang Jie, Li Weiliang, Zhou Xiuji, Shi Guangyu, Y. Iwasaka
2000, 11(2): 173-179.
Abstract:
An observational study on total ozone amount and its vertical profile is presented using the measurements taken in Lhasa in the summer of 1998. In combination with other data sets, it is proved that there is a natural "ozone valley" over the Tibetan Plateau. Analyses show that there are errors on total ozone amount between groundbased and satellite ozone measurements. Brewer Umkehr observations demonstrate that the layer with maximum amount of ozone in the stratosphere over Lhasa may exist in altitude ranging from 25 km to 27.5 km in summer, with higher values and narrower width when compared with other regions in the same latitude. But the Umkehr measurements overestimated the tropospheric ozone. Observations of ECC ozonesondes show that there has obvious lower amount of ozone in the troposphere over Lhasa in the summer season.
THE EXPERIMENT OF EXTRASEASONAL PREDICTION IN CHINA BY OSU/NCC GCM FOR FLOOD SEASON
Gao Xuejie, Zhao Zongci
2000, 11(2): 180-188.
Abstract:
Using ensemble method, tests for seasonal and annual predictions of rainfall in China during the period of 1982 to 1995 are made by the atmospheric GCM/mixed-layer ocean and ice model (denoted as OSU/NCC). Contrasts between forecasts and observations show that the model has certain ability in the prediction of precipitation for rainy season over China. It is also indicated that the prediction is especially acceptable in certain areas.
THE IMPROVEMENT AND APPLICATION OF MM5 IN NUMERICAL PREDICTION OF SHANGHAI REGIONAL METEOROLOGICAL CENTER
Gu Jianfeng, Yin Hebao, Xu Yiming, Jiang Xian 'an, Liang Xudong
2000, 11(2): 189-198.
Abstract:
According to the computer resources available in Shanghai Regional Meteorological Center and numerical forecast products of National Meteorological Center, the schemes of lateral boundary nesting, cumulus parameterization and planetary boundary layer parameterization are selected. On the basis of the dynamical frame of NCAR-PSU/MM5V2, the methods of data analysis and assimilation, post-processing and vision software of forecast products are studied. In addition, the fifth-generation operational numerical prediction system of Shanghai Regional Meteorological Center is set up and the surface element predictions per 3 h for 138 cities over East China can be provided. Through half an year quasi-operation, it is shown that the prediction performance is good, and it is valuable for the operational forecast of meteorological observatory.
COMPARISON OF SUMMER MONSOON PRECIPITATION BETWEEN NORTHERN AND SOUTHERN SLOPE OF TANGGULA MOUNTAIN OVER THE TIBETAN PLATEAU
Yang Meixue, Yao Tandong, Tian Lide, Ken′ichi UENO
2000, 11(2): 199-204.
Abstract:
Based on the precipitation data of D105 station located in northern slope and WADD station located in southern slope of Tanggula Mountain over the Qinghai-Xizang (Tibetan) Plateau obtained by GAME-Tibet fieldwork group duing May-September, 1998, the features of summer monsoon precipitation are compared.The results show that the precipitation of each side occurs with high frequency. The precipitation at WADD is 48.8% more than that at D105. However, the accumulation frequency of precipitation at WADD is a little bit higher than that at D105. Meanwhile, the mean precipitation intensity at WADD is higher than that at D105. In most cases, the daily precipitation varies similarly on each side, it is shown that the precipitation processes on both sides could be similar.
STUDY ON SOIL WATER RESOURCES IN RAIN-FED AGRICULTURAL REGION OF GANSU PROVINCE
Yang Xingguo, Ke Xiaoxin, Zhang Xudong, Wan Xin
2000, 11(2): 205-212.
Abstract:
Based on the soil moisture data of eleven stations and related meteorological data in rain-fed agricultural region of Gansu province, the spatial-temporal law of soil moisture variation and the replenishment of precipitation and the conditions of soil water are analyzed. The soil moisture decreases from southeast to northwest whereas the variation coefficient increases in the region. The variation of soil moisture mainly occurs above 90 cm depth in the region where soil moisture is insufficient and 180 cm depth or so in other three regions. The regional variation of the replenishment ratio of precipitation is about 15.3%~41.7%. In addition to the impact of precipitation on replenishment ratio, the soil type is also an important restrictive factor to replenishment. The water deficit exceeds 100 mm during wheat growing season in all stations except Chengxian, Lingxia and Xifeng, and the ratio of water deficit to wheat water requirement is about 30%~50%.
RELATIONSHIP BETWEEN CLIMATIC FACTORS AND GRAIN PRODUCTION IN YUNNAN PROVINCE
Qin Jian
2000, 11(2): 213-220.
Abstract:
The characteristics of Yunnan climatic productivity variation and the effects of climatic variation on agricultural production in the past 50 years are analyzed, and the relationships between temperature, precipitation and wheat, rice yields are mostly studied. The results show that the precipitation during Dec. to Feb. of the next year is the key factor for wheat production and the cumulative temperature higher than or equal to 10 ℃ is more favorable for rice production than precipitation. Furthermore, the periods of major climatic disasters affecting grain production of Yunnan province are diagnosed. The main meteorological disasters for the crops sown in late autumn. are drought during Jan. to Feb. and cold of the late spring during Feb. to Apr. For crops sown in late spring, the main disasters are drought in May and chilling damage during Jul. to Aug.
ANALYSIS ON THE CLIMATIC CHARACTERISTICS OF TEMPERATURE VARIATION IN TIBET DURING THE PAST FORTY YEARS
Du Jun, Zhou Shunwu, Tang Shuyi
2000, 11(2): 221-227.
Abstract:
Using the mean annual temperature data from 1952 to 1995, the climatic characteristics, interdecadal variation, climate accident, oscillation period, abnormal warm and cold variation trend are analyzed. The results show that there exist three warm periods and two cold periods for annual and seasonal temperature, 1960′s was the coldest decade, the temperature decreasing was most obvious in autumn, and the temperature was higher during the period of mid and last 1980′s and 1990′s. The periods of 22-year, 11-year and 3 or 4-year variation were significant. Climate catastrophes occurred in the early 1960′s and 1980′s. There were more anomalous cold years in 1960′s and 1970′s, whereas anomalous warm years in 1980′s. In 1990′s, the mean annual temperature of most years was anomalous. In addition, the linear trend of the warming for mean annual temperature over Tibet during the last forty years indicated an increase of 0.065 ℃/10a and the greatest warming trend occurred in the spring and autumn of the last 10 years.
CHARACTERISTICS OF OUTGOING LONGWAVE RADIATION RELATED TO FLOOD AND DROUGHT OVER NORTHEAST CHINA
Sun Li, An Gang, Tang Xiaoling
2000, 11(2): 228-235.
Abstract:
By using the outgoing longwave radiation (OLR) data and precipitation data, the temporal and spatial distribution features of the OLR anomaly patterns corresponding to flood and drought cases over Northeast China are studied. The results show that there is a close correlation between the flood and drought over Northeast China and the OLR distribution at low latitudes. There are remarkable differences for OLR anomaly patterns in the regions of ITCZ, equatorial East-Central Pacific and the subtropical high over West Pacific in flood and drought years. Furthermore, the northward propagation of low frequency oscillation of OLR over tropical and subtropical areas has great impacts on the summer precipitation over Northeast China.
CHARACTERISTIC PARAMETERS OF LIGHT RESPONSE CURVES OF PHOTOSYNTHESIS OF WINTER WHEAT IN NORTH CHINA
Lu Peiling, Luo Yi, Liu Jiandong, Yu Qiang
2000, 11(2): 236-241.
Abstract:
The photosynthesis rate of leaves in field and their corresponding meteorological elements are observed in each growing season of winter wheat in North China. The light response curves are fitted for each development duration, and characteristic parameters are obtained such as initial quantum efficiency, maximum photosynthesis rate and convexity. In the entire growth season of winter wheat in North China, the initial quantum efficiency varies between 0.05 and 0.075, the maximum photosynthesis rate varies between 5 and 25 μmol·m-2·s-1. It is shown that the initial quantum efficiency of each development duration does not vary much and the maximum photosynthesis rate ranges from 20 to 25 μmol·m-2·s-1 before heading duration, and decreases greatly in reproductive growth duration, with the decreasing of nitrogen, phosphorus and potassium of leaves.
DIAGNOSTIC ANALYSIS OF MOIST POTENTIAL VORTICITY FOR HAIL IN SOUTHERN YUNNAN
Li Ying, Duan Xu
2000, 11(2): 242-248.
Abstract:
By using the concept of moist potential vorticity, the characteristics of moist potential vorticity are analyzed in several hail events over southern Yunnan on March, 1997. The results show that very stiff moist isentropes could lead to the development of moist slantwise vorticity and the initiation of hails. The lower atmosphere has convective stability (MPV1 > 0) in hail area, but the development of moist slantwise vorticity (MPV2 < 0) could be a favorable condition to the severe convection there. Moreover, it is a good environment for hail weather to develop on the north side of areas where MPV2 > 0 and the south side of areas where MPV2 < 0.