Current Issue

01 January 2008, Volume 27 Issue 增刊   
  • Climate Change of Meiyu in Shanghai in Past a Century
  • 2008 Vol. 27 (增刊): 76-83. 
  • Abstract ( ) PDF (3023KB) ( )
  • The climatic change characteristics of Meiyu in Shanghai in past a century are examined in this paper using Meiyu data from 1875 to 2006. The basic climatic features of Meiyu in Shanghai are basically in accordance with those in the mid\| and lower\|reaches of Yangtze River. The onset time or ending time for ShanghaiMeiyu (SM) shows significant postponing trend over the past a century and more. And 1940s is a distinct turning decade for them. After then, the probability of late onset of SM increases; the probability of abnormally late (early) outset of SM increases (decreases). Furthermore, the probabilitiesfor abnormally large rainfall amount or rainfall strength e of SM are also greater after 1940s; abnormally long (short) duration time of SM tends to increases (decreases). The variation trend is not clear for the duration time and rainfall amount over the whole years discussed although they have a slight increase after 1940s compared with those before 1940s. The significant period length for the onset time, duration time and rainfall strength of SM are around 22, 4.2 and 3.3 years, respectively while its rainfall amount and ending time exhibit no obviousperiod within the years investigated. In addition, the climatically statistics of SM are in common with regional meiyu over the mid\| and lower\|reaches of Yangtze River to much extent. But the period characteristics and climate change of SM differ much with regional Meiyu.
  • Interannual Variability of Spring Persistent Rainover Southeastern China and Its Effect Factor
  • 2008 Vol. 27 (增刊): 118-123. 
  • Abstract ( ) PDF (4538KB) ( )
  • The Spring Persistent Rains (SPR) over southeastern China (SEC) is rainy season of spring and just before the onset of the South China Sea monsoon.It is a unique synoptic and climatic phenomenon in East Asia and is the result of the mechanical and thermal forcing of the Tibet Plateau (TP). The daily rainfall data at 730 stations of China in 50 years and NCEP/NCAR monthly data are employed to make the correlations and composited analysis in order to clarify the factors affecting interannual SPR rain. The results show that SPR has obvious interannual variability. In El Nioyears, equatorialmiddle\|east Pacific SST rises, the West Pacific Warm Pool (WPWP) SST drops, the West Pacific Sub\|High strengthens, and its abnormal anti\|cyclone circulation dominates over the South China Sea (SCS). The temperature rises and the southwesterly strengthens at lower troposphereover SCS. As a result, SPR rain significantly increases. And vice versa, in La Niayears, SPR rain remarkably decrease. In addition, time\|lag correlation analysis shows that the tropical Pacific multivariateENSO index (MEI) significantlycorrelates with SPR rainfall leading 6 months. In conclusion, ENSO, the largest and the strongest global climate abnormity event, also has profound effects on the circulation and rainfall of the transferringSPR over southeastern China.
  • Characteristics of Maximum and Minimum TemperatureVariations and Their Differences between Urban andSuburban Areas in Shanghai from 1960 to 2006
  • 2008 Vol. 27 (增刊): 124-130. 
  • Abstract ( ) PDF (2262KB) ( )
  • Based on the temperature data at 10 meteorological stations in Shanghai, the temporal and spatial variation characteristics and the difference of maximum and minimum temperatures between urban and suburban areas in Shanghai during 1960\_2006 were studied. The results indicated that in the past 47 years, the mean annual maximum and minimum temperatures are 20.1℃ and 12.5℃, respectively, increased with a tendency ratio of 0.29℃/10a and 0.39℃/10a in turn. The maximum temperature increase the highest during spring and the minimum temperature increase the highest during winter. Both the maximum and the minimum temperatures raised an abrupt change in the middle and end of 1980s, with the abrupt timing of 1988 and 1989, respectively. Both the maximum and the minimum temperatures were negative departure before 1990s, and then had been turned to be positive one since 1990s . The difference of maximum and the minimum temperatures between urban and suburban areas has been significant since 1987. The maximum temperature in urban areas was higher than those both in suburban areas, and also the maximum temperature in inland higher than that along river and coastal regions. The difference of maximum temperature between urban and suburban areas in recent 20 years was 0.4℃ higher than that of during 1960\_1980, and the difference of maximum temperature between urban and exurban areas was 0.6℃ higher than that of during 1960\_1980. The spatial pattern and variation trend of minimum temperature were roughly the same as the maximum temperature. In recent 20 years, the difference of minimum temperature between urban and suburban areas was 0.5℃ higher than that of during 1960\_1980, and the difference of minimum temperature between urban and exurban areas was 0.8℃ higher than that of during 1960\_1980. The mean daily range of air temperature was 7.5℃ Shanghai, being decreased significantly in the past 47 years. The decrease of daily range of air temperature was probably to associate with the asymmetrical variation of the maximum and minimum temperatures; moreover, and it significantly it associate with the sunshine duration and cloud cover too.
  • Statistical Analysis of Atmospheric Precipitable Water VapourObserved by GPS in Yangtze River Delta Region
  • 2008 Vol. 27 (增刊): 150-157. 
  • Abstract ( ) PDF (5526KB) ( )
  • The climate features of atmospheric water vapor in Yangtze River Delta region are analyzed by use of 7 years′ Precipitable Water Vapor(PWV) data observed by GPS observational Network, and the relations between climate characteristics of Atmospheric Precipitable Water vapor and heavy rain in Meiyu season are also studied. The results show that: PWV distribution in the Yangtze River Delta region are the higher the north and higher the west, the average PWV during summer months are higher than that of the winter months about 20mm, and the PWV gradient from south to north is clearly higher than that from west to east, which shows that moisture transportedto Yangtze River Delta region by northern flow is important. PWV in Yangtze River Delta region has a significant seasonal change, the maximum PWV are found in August in summer, and the minimum PWV occurred in January in winter, and the PWV changes in spring and autumn are strong than that in summer and winter; while the PWV in Yangtze River Delta region has no significant cyclical changes in year and in day. In addition, there is obvious correlation between PWV and severeprecipitation duringMeiyu Period, when the PWV value quickly increase from the low-value to more than 60 mm, or PWV values remained at high values after severeprecipitation, severeprecipitation often occurs, which maybe provides a new signal for us to forecasts heavy rain in the Yangtze River Delta.
  • A PV Inversion Analysis of Strong Cyclone over the Yangtzeand Huaihe River Valleys during the Meiyu Period of Summer
  • 2008 Vol. 27 (增刊): 158-169. 
  • Abstract ( ) PDF (15829KB) ( )
  • In the potential vorticity (PV) framework, the process of a strong cyclongenesis is analyzed and researched in detail during Meiyu periodin 2003 based on piecewise Ertel PV inversion techniques. Results show that the forcing effect at upper\|level exerts important impacton the development of low\|level cyclonic circulation, which mainly enhanced north wind on the upstream and south wind on the downstream of low\|level cyclone and consequently brought aboutdevelopment of high pressure ridgeson the upstream anddownstream of the cyclone. Theyprovide favorable background for enhancement of the cyclone as well asfurther strengthenthe cyclonic vorticity in the mature process of cyclone. At the same time, the low\| and mid\|level perturbationsalso play important role in the development of low\|level cyclonic circulationfrom beginning to end. It can strengthen the south wind on the downstream of low\|level cyclone center and further enhance the cyclonic circulation, which also does important contribution to the formation of upper\|level cyclone. On the other hand, the heatinganomalyat bottom exerts adverse effects on development of low\|level cyclonic circulation by decreasing the cyclonic vorticity. In addition, the analysis about effects of dry or moistair suggest that saturation moist air plays a significant role on decrease of geopential height on the center of low\|level cyclone and surfacepressurebesides strengthening of low\|level cyclonic circulation.
  • Preliminary Study on the Biology and Ecology Characteristicof Direct Sowing Rice Optimal Seeding Stages
  • 2008 Vol. 27 (增刊): 183-189. 
  • Abstract ( ) PDF (3033KB) ( )
  • Using the method of correlation analysis to analyze different seeding data of direct sowing rice, the results showed thatthe relation between rice yield and seeding date in Shanghai area is the parabola type, and optimal seeding time of direct sowing rice in Shanghai region is on 13 June. The best effective panicle numberunder the best seeding date is 360×104 hm-2, with 105 grains on per panicle, 11%~12% of unfilled\|grains rate, 25 g of 1000\|grain weight, 43%~44% of economic coefficient, and 150 days during the whole growing season. The correlation coefficientbetween yield and the leaf area index of the peak period of tiller, dry matter weight of leaf are -0.8957( P<0.05) and -0.9928 (P<0.01), respectively. The correlation coefficient that yield and leaf area index, dry matter weight duringheading to maturityare 0.8505 (P<0.1) and 0.8130 (P<0.1), respectively. During the tiller period and higher tiller period, sunshine durationare higher than 70 h,the effective panicle number obviouslyincreases.When sunshine durationbetween initial panicle formation tocell divisionislower than 160 h, total grains obviously decreases. When the minimum air temperature while blooming is lower than 18℃, the rate of unfilled grain reaches above 18%. Average minimum air temperature before and after headingis lower than 23℃ or sunshine durationis lower than 200 h, 1000\|grain weight is lower than 23 g.
  • Characteristics of Temporal Variability of Soil Moisture in Shanghai
  • 2008 Vol. 27 (增刊): 190-195. 
  • Abstract ( ) PDF (3619KB) ( )
  • Based on continuously soil volumetric water content datum of 3 observationstationsin Shanghai from 1 July 2007 to 30 June 2008 with a time resolution every 30 min and daily precipitation, the characteristics of temporal variability of soil moisture and precipitation in Shanghai and its relationship were analyzed using trend analysis method. The results indicated that there were mostly unimodaldistributions of daily variability of relative moisture of soil in all seasons of 10~30 cm in Shanghai, except for unimodaldistributions of relative moisture of soil in 40 cm and 50 cm in winter, distributions of which in other seasons were not obviously. There werefour distribution types of daily variability of relative moisture of soil infive depthsin sunny, overcast, cloudy and rainyday,and the time appearing of wave crest and wave troughin 10~30 cmpassedbackward with the increasingof soil depth. Distribution of 10 day relative moisture of soil in shallow soil wasmore identical with which of 10 day precipitation than deeper layer, and thefluctuate intensityof 10 day relative moisture of soil of deeper layer wasslightly less than the shallow layer of soil.
  • An Application of Microscale Meteorological Modelto Environment Impact Assessment
  • 2008 Vol. 27 (增刊): 203-209. 
  • Abstract ( ) PDF (3708KB) ( )
  • Using the microscalemeteorological model(Envi\|met) and gaspollutiondispersion model, and taking the Ruijin No2 road businessbuilding project in Shanghai as an example, the influence of the traffic waste gas on the buildings is simulated. Based on the parameters such as the distribution characteristics of buildings and underlying surface, and verified wind direction, wind speed, the intensity and heightof pollutant, the finized spatial distributionof gas pollutant densityover related area is obtained with the Envi\|met model, andfurthermore, the simulations by Envi\|met model are compared with that by regulatory atmospheric dispersion model. Theresults indicate that simulations from two models are relatively similar with each other, and because of covering the rather real distribution characteristics of buildings and wind fields around them, Envi\|met model presents the more reasonable and detaildistribution of gas pollutant. The applications of microscalemeteorological models to environmentimpact assessment can be used to supplement the regulatory atmospheric dispersion modeland seemly will have good prospectsin application.
  • Evaluation on Effects of Meteorological Conditions on ElectricalComsumption in Megathermal Days of Shanghai
  • 2008 Vol. 27 (增刊): 210-217. 
  • Abstract ( ) PDF (1744KB) ( )
  • The impact of meteorological condition on the electric consumption in shanghai was appraised using the data such as the daily electrical consumption, maximum electricity load and meteorological elements from June to September of 2003\_2006 and 121 megathermal days of 2003\_2006. The results showed that the risk of the high\|increasing of daily electricity consumption and maximum electricity load in megathermal days were higher than that from June to September. The fore\|and post\|evaluation model of the meteorological variation of the daily electricity consumption and maximum electricity load were constructed, and the fitting errors of the model were analyzed from June to September and in megathermal days, the regression of the model were significant statistically, the fitting results of the model in megathermal days were better than those from June to September. The evaluation model made the satisfied performance from June to September and the megathermal days of 2007, the performable results of the model in megathermal days were better than those from June to September, but the fore\|evaluation errors tended to increase when the sudden fall\|down of temperature occured during persistent high temperature days, similarly, the post\|evaluation error of the model tended to increase on rainy day during the high temperature days.