Analysis of a Typical Case of Meteorological Service in Tangpu Reservoir

The continuous rainy precipitation process from February to March in 2019 was selected to analyze the effect of meteorological service in Tangpu Reservoir basin,so as to sum up service experience and then lay a better foundation for subsequent services.In response to the rainy weather from December 2018 to early 2019,three rounds of flood discharge were carried out in Tangpu Reservoir.During February-March in 2019,the hit rate of short-term area rainfall forecast for Tangpu Reservoir was 80.0%.Compared with the median of forecast interval,the average absolute error was 7.6 mm,and the relative error was 32.7%.The large deviation in the forecast from March 27 to 28 was deeply analyzed,and it is found that the main reasons were excessive reliance on and trust in a single model,insufficient correction of the actual situation,and insufficient judgment of the nature of precipitation.For the future reservoir meteorological service,three aspects of thinking were put forward,such as further strengthening the sharing of hydrological and meteorological information,improving the forecasting ability,and deepening the research of runoff forecast models.

Analysis of Differences between Requirements of Public Meteorological Services from a New Perspective

Based on the survey data of public meteorological services,differences between users' needs for public meteorological services were analyzed by using Maslow's hierarchy of needs and the principle of information availability in behavioral economics. The results show that users' needs for meteorological services follow certain laws,and the public's needs for meteorological information are driven by physiological needs firstly and then by safety needs,while they are driven by upper needs finally. Meanwhile,users' needs for meteorological services have particularity.Under special backgrounds,there are certain differences between users' needs and laws of basic needs,and users' needs are inconsistent with the " ideal needs" of meteorological departments. Studying the laws and particularity of differences between users' needs for meteorological services in detail is conducive to a survey of the public's needs for meteorological services and improvement of meteorological service quality.

Application of Electronic Sand Table System in Geological Disasters Meteorological Service Based on GIS

With complex terrain and developed economy, Zhejiang Province has suffered a lot from the frequent geological disasters, which have done great damages to the construction and development of the whole province. Therefore, it is particularly important to improve the geological disasters meteorological service. Electronic sand table system, a high-tech product of three-dimensional visualization, can provide the geological disaster meteorological service with the intuitive and visual application environment. In this study, we developed electronic sand table system based on GIS and established the geological disasters meteorological service database. In addition, we also analyzed and discussed the applications of meteorological service in online weather forecast, meteorological warning message, and multimedia meteorological electronic display. The application of electronic sand table system in geological disaster meteorological services for disaster prevention and mitigation is of great importance that it provides intuitive terrain analysis data for the forecast of geological disasters warning, which greatly enhances the ability of geological disasters meteorological service.

Temporal Variations in Sea of Clouds and Their Relation with Meteorological Factors in Yandang Mountains

Based on data of meteorological elements in the meteorological station in North Yandang Mountains during 1960- 2013,temporal variations in days of sea of clouds over Yandang Mountains in nearly 50 years and their relation with air temperature,precipitation,relative humidity and wind speed were analyzed. The results showed that annual average days of sea of clouds over Yandang Mountains were 164. 92 d,and the maximum and minimum were 215 and 58 d,so there was a big difference between various years. The days of sea of clouds were the most in spring,and average days of sea of clouds（ average days of sea of clouds with low cloud cover ≥80%） were 50. 89 d（ 32. 77 d）,while they were the least in autumn. There was an obvious positive correlation between the days of sea of clouds and relative humidity. Precipitation occurred the day before or on the day when sea of clouds with low cloud cover ≥80% formed. On the day when sea of clouds with low cloud cover ≥80% appeared,average relative humidity was ≥80%,and average wind speed was ≤4. 5 m/s.

Changes in the Beginning Date and Duration of the Four Seasons in Zhejiang Province

Based on data of daily average temperature from 62 national ground observation stations in Zhejiang Province during 1971-2015,the changing trends and spatial distribution of beginning date and duration of the four seasons in Zhejiang Province were analyzed by using the least square method,and significance test was conducted by using correlation coefficient. The results show that according to the changing characteristics of the four seasons in Zhejiang Province,autumn and winter began later,while spring and summer started earlier than before; the duration of summer lengthened,while the duration of winter shortened,and there were great changes in summer and winter but small changes in spring and autumn. Seen from the spatial distribution of beginning date and duration of the four seasons,the correlation in middle and northern Zhejiang was better than that in southern Zhejiang.

Study and Application of Evaluation Method for Weather Impact of Traffic Accident on Zhejiang Freeway

Occurrence degree of the accident on Zhejiang freeway is graded. Evaluation indicator system of weather impact on freeway is established. We use principal component analysis to extract meteorological indicators,and use Logistic regression to establish evaluation model of meteorological indicator,thereby determining evaluation grade of traffic weather impact. Via application test,it is proved that the evaluation on traffic weather condition by the model corresponds with actual situation,which can provide certain decision-making basis for traffic department and the public.

Establishment and Application of Comprehensive Evaluation Index of Tourism

According to the actual situation of Zhejiang Province,an objective and quantitative mathematical model used to assess the tourism index of scenic spots was proposed to extend fine and personalized meteorological services to scenic spots and tourists,in which effects of sunshine,wind power,temperature and relative humidity on the comfort of the human body were considered fully,and warning of weather disasters and occurrence of characteristic meteorological landscapes were also considered. The results show that the comprehensive evaluation index model of tourism has full functions of assessment,has guiding significance to the travel of travel enthusiasts and can provide reference for tourism management.

Characteristics Analysis of Extreme Circulation at 500 hPa of Height Field in Eurasian Region during Recent 20 Years

[ Objective] The research aimed to analyze extreme circulation characteristics at 500 hPa of height field in Eurasian region in recent 20 years. [ Method ] Based on NCEP/NCAR reanalysis daily data at 500 hPa of height field from 1961 to 2009 of Eurasia （15° -80° N, 40° -150° E）, seasonal and monthly change situations of extreme circulation in Eurasia were studied by the method of climatologically equally likely intervals （ CE- Ll）. [Result] Growth rate of extremely low circulation increased in Eurasia in the last 20 years, but the rise amplitude was smaller. In the middle of China and Mongolia, grow rate change of extremely low circulation was the smallest. The growth rates of extremely high circulation in spring, au- tumn and winter gradually decreased as latitude rose. The maximum growth rate of extremely high circulation in summer was in Qinghai -Tibet Plat- eau, which corresponded with the climate characteristics of summer subtropical high going northward and then retreating southward. By contrasting the growth rates of extremely low and high circulation, it was clear that the growth rate of high circulation was higher than that of the low circulation. [Conusion] The research could be as a reference for studying change characteristics of the extreme climate event in China.

Prediction of Lifespan of Tropical Cyclones Landing at China in Spring:A Case Study of Northward-moving-cluster Tracks

The recurving cluster of tropical cyclones(TCs)landing at China in spring has the characteristics of high frequency,strong intensity,severe influence and long lifespan,a better understanding of tropical cyclone tracks and their underlying mechanisms and more accurate prediction are thus of great value for the prevention and mitigation of TC-related disasters.Based on the best track dataset of typhoon during 1951-2018 from Shanghai Typhoon Institute(STI)of Chinese Meteorological Administration,the tracks of tropical cyclones landfalling over the Chinese coast during 1951-2018 are grouped into three clusters through finite mixture model.The ENSO index,PDO index and the 74 circulation indices of the National Climate Center are analyzed by the classification and regression tree(CART)algorithm for the first TC cluster(the northward-moving cluster).The prediction model based on the results of CART for spring track lifespan is built by a random sampling of the data during the 50 years(about 75%)as a model of the training set,and the training accuracy is 82.46%.The 17-year(about 25%)remaining data are used for testing,with a prediction accuracy of 75%.This study suggests that the finite mixture model algorithm produces a better classification of the northward-going-cluster tracks of TC landfalling over China.In addition,the CART algorithm,which is used for the classification of track lifespan prediction model,not only shows high accuracy,but also the results are easily explained and understood.It provides a novel idea for forecasting the lifespan of tropical cyclones landing at China.

Research on Weather Routing Based on the Mobile Internet

The combination and application of the mobile internet techniques with the weather radar monitoring data and the numerical weather pre-diction data were introduced, and the smart phone weather routing application software for both land and aquatic traffic safety, which is equipped with the function of analysis and warning of disastrous weather, was developed to reduce potential weather risks encountered during the journey as much as possible.

Variations of Winter Precipitation over Southeastern China in Association with the North Atlantic Oscillation

The synoptic-scale winter precipitation variations over southeastem China （22°-32°N, 105°-125°E） and their asso- ciation with the North Atlantic Oscillation （NAO） during 1951-2007 are investigated in this paper. The variability of wintertime precipitation is characterized by meridional displacement of its maximum center. Two precipitation re- gimes, with maximum centers located over the Yangtze and Pearl River basins, are identified via cluster analysis. Time-lagged analyses suggest that the two precipitation regimes are connected with the decaying phases of positive NAO （NAO＋） events of different amplitudes. A strong （medium） NAO＋ event is defined as one when the maximum amplitude of the NAO index exceeds 1.0 （in the range of 0.7-1.0） for at least 4 consecutive days and drops to less than 0.3 within 7 days following the peak index. After the peak of a strong NAO＋, southerly winds expand north- ward to the Yangtze River （about 30°N）, a northeast-southwest-tilted trough migrates to east of Lake Baikal, and cold air intrudes into central eastern China; thus, precipitation is strengthened over the Yangtze River basin where warm and cold air masses converge. In comparison, during the decaying phase of medium NAO＋ events, the south- erly winds are relatively weak, and precipitation tends to be enhanced at lower latitudes （around 25°N）. Further ana- lysis indicates that downstream Rossby-wave propagation may account for the latitudinal expansion of the southerly wind anomalies over the eastern coastal area of China during the decaying phase of NAO＋ events of different strengths.

Agro-climatic adaptation of cropping systems under climate change in Shanghai

Climate change affects the heat and water resources required by agriculture, thus shifting cropping rotation and intensity. Shanghai is located in the Taihu Lake basin, a transition zone for various cropping systems. In the basin, moderate climate changes can cause major shifts in cropping intensity and rotation. In the present study, we integrated observational climate data, one regional climate model, land use maps, and agricultural statistics to analyze the relationship between heat resources and multi-cropping potential in Shanghai. The results of agro-climatic assessment showed that climate change over the past 50 years has significantly enhanced regional agro- climatic resources, rendering a shift from double cropping to triple cropping possible. However, a downward trend is evident in the actual multi-cropping index, caused principally by the increasing costs of farming and limitations in the supply of labor. We argue that improving the utilization rate of the enhanced agro-climatic resources is possible by introducing new combinations of cultivars, adopting more laborsaving technologies, and providing incentives to farmers.