应用气象学报

2003, 14(2)

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Abstract:

TROPICAL INDIAN OCEAN SUBSURFACE DIPOLE MODE AND DIAGNOSTIC ANALYSIS OF DIPOLE EVENT IN 1997/ 1998

Qian Haifeng, Yin Yonghong, Ni Yunqi

2003, 14(2): 129-139.

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Abstract:
The tropical Indian Ocean subsurface temperature anomaly above 400 m is studied by using the method of EOF and other statistic methods, and the 1997/98 tropical Indian Ocean dipole event is analyzed.The results show that the largest temperature anomaly in the tropical Indian Ocean subsurface layer above 400 m is around the depth of 100 m.As for the whole tropical Indian Ocean, the subsurface layer above 60 m appears to have a warming trend since the 1980' s, while the subsurface layer below 80 m to have a cooling trend.The subsurface layer of 80 m has an obvious dipole mode, which is much stronger than that of the sea surface.In 1997/98, the dipole event of the sea surface in the Indian Ocean was resulted from the westward ex tension of the temperature anomaly over the eastern Indian Ocean.The westward ex tension of the temperature anomaly was related to the easterly anomaly over the tropical Indian Ocean, where the easterly anomaly might trigger the Rossby wave and induce the temperature anomaly to ex tend westward.

CHARACTERISTICS OF ATMOSPHERIC CIRCULATION ANOMALIES DURING PERSISTENT DROUGHTS IN NORTH CHINA FOR LAST TWO DECADES

Wei Jie, Zhang Qingyun, Tao Shiyan

2003, 14(2): 140-151.

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Abstract:
The persistent droughts during the last two decades in North China are studied.The main results are as follows :(1) The Palmer Drought Severity Index (PDSI) shows that there is inter-annual variation in droughts in North China.The inter-decadal variation is even more remarkable.Before the mid-1970s, there was wetsummer climate, while since 1970, there were more drought years in North China.Moreover, the most severe droughts happened after the 1980s.(2) Summer droughts in North China are the consequence of persistent anomalous circulation over the Eurasia.The main features of the anomalous circulation include that there is height anomaly in the region of 55°to 65°N, 60°to 135°E and that there was EU teleconnection and it is the main type of atmospheric circulation anomalies that causes the persistent summer droughts in North China.(3) During the summer drought years, there is continuity in the distribution of the 500 hPa height anomaly field from winter to summer.(4) The anomalies of the general atmospheric circulation during droughts in North China are not local phenomena, but the responses to the Northern Hemisphere general atmospheric circulation anomaly.

IMPACTS OF CLIMATE WARMING ON THERMAL AND MOISTURE CONDITIONS IN NORTHEAST CHINA IN RECENT 20 YEARS

Wang Shili, Zhuang Liwei, Wang Futang

2003, 14(2): 152-164.

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Abstract:
The characteristics of climate warming, instability and extreme climate events as well as changes in atmospheric moisture and the corresponding thermal and moisture conditions in Northeast China in recent 20 years are analyzed based on data in 1961-2001 in 56 meteorological stations.The results show :(1) The temperature increment amplitude in winter is significant; the 1990's climate warming is stronger than the 1980's; and the increment in the southern part is larger than that in the northern part.(2) The temperature increment in summer is limited; the temperature variance is unstable, and extreme climate events such as days of high temperature occur frequently.(3) The increment in minimum temperature is much larger than that in maximum temperature, which results in the reduction of temperature diurnal range; the change is more obvious in winter.(4) There is no significant change in atmospheric moisture deficit and the corresponding thermal and moisture conditions at 10-year scale; however, there are evidences of warming and drying in recent 5 years and the warming and drying periods occur frequently in summer as well as in the southern and western parts.Warming and drying in summer is unfavorable to crops.

CORRECTIONS TO NOAA/AVHRR REFLECTANCE AND NDVI AND THEIR ERROR ANALYSIS

Wang Kaicun, Chen Changhe, Guo Ni

2003, 14(2): 165-175.

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Abstract:
NOAA/AVHRR reflectance and normalized difference vegetation index (NDVI) data have been widely used in meteorological and hydrological fields.Because the bi-directional reflectance distribution of surface and the scatter and absorption effects of atmosphere, even though the surface keeps unchanged, the reflectance obtained by satellites can vary greatly.After cloud-removing and degradation-correcting processing, atmospheric corrections are carried out to NOAA/AVHRR visible and near-inf rared reflectance and NDVI data using the 6S model, and then bi-directional reflectance corrections are carried out.The atmospheric correction makes the visible reflectanc decrease by 3.34 (reflectance unit), the near infrared reflectance increase by 3.43 (reflectance unit), and increases the NDVI increase by 0.22, equaling to 78.2 percent, 15.9 percent and 35.5 percent of theirown respectively.The bi-directional reflectance correction does not affect the amount of NDVI distinctively, but can remove the irregular variances of the reflectance and NDVI.After corrections, the reflectance and NDVI can reflect the phenological effect of deciduous forests (the land cover of the surface target).At last, based on the error analysis, the sensitivities of correction errors to the errors of correction parameters are given, and the results show that the solar and satellite zenith angles are the most sensitive parameters.

APPLICABILITY OF SINGULAR VALUE DECOMPOSITION AND SINGULAR CROSS-SPECTRUM TO DIAGNOSE OF RAINFALL IN NORTH CHINA

You Fengchun, Ding Yuguo, Zhou Yu, Shi Yinshan

2003, 14(2): 176-187.

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Abstract:
Based on the monthly mean precipitation data of 1965-2000 from 73 meteorological stations in North China, the diagnostic analyses of the January Northern Hemisphere 500 hPa height field and the winter Northern Pacific Ocean sea surface temperature (SST) field associated with summer precipitation over North China are made by singular value decomposition (SVD) and singular cross spectrum analysis (SCSA) methods.The results show that there is a close PNA teleconnection pat tern between 500 hPa height field and summer North China precipitation when the summer precipitation anomaly is positive.ENSO has a definite impact on summer North China precipitation, but there is not no table relation between summer precipitation and winter ENSO in the Northern Pacific Ocean when the precipitation anomaly is positive.The key regions of interaction between North China precipitation and Northern Hemisphere 500 hPa height field and that between precipitation and SST are further found.For the interaction between North China precipitation and 500 hPa height field, the dominated coupled oscillation periods are quasi-two years and quasi-seven years.For the interaction between North China precipitation and SST, the periods are longer———the shortest is the quasi-2-year oscillation and the longest is 10-or 11-year oscillation.

RECONSTRUCTION OF JANUARY TO APRIL MEAN TEMPERATURE AT QINLING MTS FROM 1789 TO 1992 USING TREE RING CHRONOLOGIES

Liu Hongbin, Shao Xuemei

2003, 14(2): 188-196.

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Abstract:
The mean temperature of January to April was reconstructed for the period of 1789 to 1992 using standard treering chronologies of Foping, Qinling, Shaanxi Province.The growth of Pinus tabulaeformis Carr., Abies chensiensis Van Tieghem and Tsuga chinensis Beisen at Muwangping, Guangtoushan, Sangebao and Sanguanmiao, whose altitudes are from 1500 to 2850 meters (a.s.l.), is significantly affected by the local January to April mean temperature.The correlation coefficient between the temperature series reconst ructed by the regression and the observation data is up to 0.60, with an equation confidence level of 0.01 and highly significant cross-verification testing parameters.A period of three to four years is found significant in the reconstructed series by the power spectrum method.The abrupt changes of standard deviation, in ten years scale, are detected around 1896 by means of the smoothing t Test, smoothing F Test and Lepage Test, apparing as the amplitude variation of temperature fluctuation.

LARGE APERTURE SCINTILLOMETER AND ITS APPLICATION TO SURFACE ENERGY BALANCE MONITORING

Hu Liqin, Wu Rongzhang, Fang Zongyi

2003, 14(2): 197-205.

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Abstract:
The large aperture scintillometer (LAS) is a device that measures the turbulent intensity of the refraction index of air.The instrument consists of a transmitter and a receiver, which are placed at a given distance apart with the path length being to 5 km.Therefore, the measurement of LAS is an area-averaged result between the transmitter and the receiver.At the receiver the spatial turbulent intensity is expressed in the refractive structure index C_n². With some additional data users are able to derive the sensible heat fluxes between surface and atmosphere.As part of the Chinese-Dutch CEWBMS (China Energy and Water Balance Monitoring System) project, five LASs were installed in China.As one site representing the agricultural area in North China, a LAS was set up over a crop field at Zhengzhou in Henan Province with a path length of 1350 m.Using the LAS measurements and some additional data collected in the Zhengzhou site in 2000, daily average sensible heat fluxes are deduced, and the basic characteristics of surface energy balance components during the w hole year are analyzed.The results show a good consistence with the features of the rainfall and the soil relative humidity in the same period.This work improved the understanding of the seasonal variation of the energy balance in the LAS site area; furthermore, provided the phy sical foundation for the LAS application in local surface energy balance monitoring.

STUDY OF MICROWAVE CHARACTERISTICS OF RAINFALL OVER SOUTH CHINA AND YANGTZE RIVER BASIN USING TRMMDATA

Wu Qingmei, Cheng Minghu, Miao Chunsheng

2003, 14(2): 206-214.

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Abstract:
TRMM (Tropical Rainfall Measurement Mission) was launched in December 1997, which carried a space radar for the first time and the related data have been made available to the public users since June 1998.The microwave characteristics of rainfall over South China and the Yang tze river basin are investigated by using TMI (TRMM Microwave Imager) data and TRMM-derived precipitation products through Is (Scattering Index) algorithm.The expression of the I_sis regressed by the TMI data on sunny days.For 14 rainfall cases, the relationship between the I_sprecipitation threshold obtained through the "area equal" method and the precipitation area and the coldest top temperature of 85.5 GHz vertical channel is investigated.At the same time, the correlation between I_sand surface instantaneous rain intensity is studied.The result shows that the I_sthreshold has the increasing tendency when the precipitation area increases or the top temperature decreases, and I_s≥60 K is a good index of rainstorm.The instantaneous rain intensity is retrieved, and it is found that I_scan be used to retrieve rain intensity better because of the improvement of data resolution and the temporal and spatial consistency of the data.

SPACE-TIME DISTRIBUTION AND PHYSICAL MECHANISMS OF AUTUMN RAINS IN WEST CHINA IN 2001

Bao Yuanyuan, Abulimiti, Li Feng, Wang Xiuwen

2003, 14(2): 215-222.

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Abstract:
The space-time distribution features of autumn rains in West China in 2001, the related large-scale atmospheric circulation, and the main features of the weather systems are analyzed to study the physical mechanisms of autumn rains.The results show that there were more rainy days than normal in 2001, and the strong raining processes were concent rated around Sichuan Basin in September.The circulation analyses show that there was a quasistationary t rough near the Oz.Balchas, from which short waves were split one by one, moved southeastw ard, passed Tibet Plateau and reached the area near Sichuan Basin.Here the cold ai rs taken by the short waves were combined constantly with the warm and humid southeastair in the southeast side of the strong subtropical high and with the wet-warm south west air from the Bay of Bengal.The physical analyses show that there was a strong energy frontal zone between the high energy center in Tibet Plateau and the lowenergy center to the east of Sichuan Basin.So the short waves were developed strongly in the Basin. The intensity of the energy frontal zone was streng thened because the cold air from the east area entered so that the instability energy burst out, which triggered the rainstorm in Sichuan Basin.

A NEW STATISTIC FORECASTINGMETHOD OF SO₂ POLLUTION AND ITS APPLICATION

Yang Wenfeng, Shi Baozhong

2003, 14(2): 223-229.

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Abstract:
Concerning the limits of the currently used statistic methods of air pollution (not considering correlation and non-orthogonality among forecasting factors results in regression instability and more errors), the linear regression and empirical orthogonal function (EOF) are combined with the stepwise reg ression analysis method, and thus a new fo recasting method in the building forecasting model is proposed.By using this method for forecasting SO₂ density in the heating period, the model fit ting and forecasting show that these models can not only fit the changing tendency of SO₂ density, but also fo recast SO₂ densi ty qui te well, e.g., the grade accuracy is 72.5 percent.In cont rast with the step wise reg ression analysis method, during the forecast experiment, the result of the new forecasting method is more accurate. The new forecasting method has good prospect in application.

DISTRIBUTION AND SEASONAL VARIATION OF FRIED PARAMETER AT GROUND LEVEL IN CHINA

Li Shuangxi, Fu Yuanfen, Huang Yinliang, Li Jianguo, Mao Jietai

2003, 14(2): 230-235.

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Abstract:
Based on the standard meteorological radiosonde data in the years of 1986 to 1995, the Fried parameter r₀ is calculated by means of the theoretical model of Tatarski over 81 meteorological stat ions in China.The geographical distribution of the annual mean r₀ at ground is in accordance with the topographical distribution basically.The effect of the variation of atmospheric turbulence on the local distribution of r₀ is apparent.The locations of the high monthly mean r₀ centers are different in different seasons and all these differences are related to the seasonal behavior of the subtropical jet stream possibly.

STUDY OF CLIMATIC ADAPTABILITY OF TWO-LINE HYBRID RICE SEED PRODUCTION

Deng Fangping, Yao Kemin, Su Gaoli

2003, 14(2): 236-244.

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Abstract:
The research on the climatic adaptability of the predominant sterile line, Peiai-64S, can provide references for decision-making in the production of two-line hybrid rice and the study of other sterile lines.The g row th model is constructed by using the number of days from seeding date to heading date and the corresponding meteorological data.The fertility model is developed based on the seed-set ting rate along with the corresponding meteorological data, and the switch indices of critical sterility induced by temperature and day-length are calculated. The 42-year meteorological data of 35 weather stations in China are input into the grow th model and the potential duration for the heading period (the duration from the earliest heading date to the latest heading date) is deduced for each station.According to the switch indices of critical sterility induced by temperature and day-length, the beginning and ending dates of the sterile and fertile duration under the guarantee rates of 80 %, 90 % and 95 % are given.During the sterile duration Peiai-64S can be used for producing hybrid seeds; and during the fertile duration, it can be used for multiplying itself.The results show that Peiai-64S can multiply only in Hainan Island or in the lower altitude area of the Yungui Plateau, whereas it can produce hybrid seeds in any rice production regions except Northeast China and the Yungui Plateau.The seasons for producing hybrid rice seeds are related to the altitude and latitude of the rice planting areas.

EXPERIMENTAL STUDY OF SINGLE AND INTERACTIVE EFFECTS OF DOUBLE CO₂, O₃ CONCENTRATIONS ON SOYBEAN

Bai Yueming, Wang Chunyi, Wen Min, Huang Hui

2003, 14(2): 245-251.

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Abstract:
The single or interactive effects of double CO₂ and O₃ concent rations on soybean (Gly cine max L.Merr.) are investigated for first time by using a soybean cultivars, Zhonghuang-14, in an open-top chamber.Cont rasting to the control, the effects of doubled CO₂ concentration alone on soybean biomass, yield, legumen bunches, legumen numbers, grain numbers and weight are posit ive, but the effects of doubled O₃ concent ration alone on the above parameters are obviously negative; and the longer the ventilation time periods are, the more obvious the effects are.When both CO₂ and O₃ concentrations are doubled, their interaction shows that the effect of CO₂ is greater than that of O₃.In the process of CO₂ and O₃ concentrations increasing gradually, the negative O₃ effect approached the posi tive CO₂ effect eventually because of the gradually cumulating O₃ concent ration and gradually increasing stimulation.The doubled O₃ concent ration alone suppresses photosynthetic products into the soybean roots and grains, but increases those into soybean stems and leaves, resulting in the reduced root/shoot ratio (RSR) and grain/culm ratio (GCR).The long-period effect reduces Harvest Index (HI) and increases Leaf Weight Ratio (LWR) markedly.With the ventilation time prolonged the effects are more remarkable.The interactive effects of doubled CO₂ and O₃ concentrations on the RSR、LWR、GSR and HI are relatively slight, only within±10%.

RESPONSE OF STIPA BAICALENSIS TO SOIL DROUGHT STRESS AT HIGH CO₂ CONCENTRATION

Gao Suhua, Guo Jianping, Zhou Guangsheng, Yang Limin

2003, 14(2): 252-256.

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Abstract:
Stipa Baicalensis is one of regional herbs in the eastern Inner Mongol and the western Northeast China.Throug h an art if icial simulation experiment, the "fertilizat ion" effect of CO₂ concent ration enrichment on Stipa baicalensis is analyzed.The results show that the biomass and growth value of the herbage, the Pcontent in the root, and C, N, P contents in the leaves increase with CO₂ concentration enrichment.The impacts of soil drought stress on the biomass and grow th value are all negative.Mo reover, the impact is more remarkable with the agg ravating drought deg ree.Soil drought increases C, N contents in the herbage leaves and roots.

Vol.14, NO.2, 2003