Changing Characteristics on Dust Storm in Jiangsu

Based on observation data of dust storm for the years 1960-2006 from weather stations across Jiangsu, this essay provides a statistical analysis on the characteristics and trends, including the timeframes and regions of the incidences of four weather phenomena: sandstorm, blowing sand, floating dust and haze in an effort to better understand the trend of dust storm changes in Jiangsu Province, China. The result indicates that, on average, the incidences of sandstorm, indi- cated with the total number of days in a year in Jiangsu is low and on a declining trend. With the improvement of the environment, no sandstorm has been observed for many years. In general, those of blowing sand and floating dust have been reducing, and showing a significant improvement during the recent years. What should be noted, however, is the accelerated increase in haze incidences, particularly, in Southern Jiangsu.

Genetic Analysis of a Strong Convective Weather Process in Guannan County

To provide references for the forecast of strong convective weather process by county-level stations, through synoptic analysis, diagnostic analysis of physical quantities, analysis of satellite cloud pictures and new generation of weather radar data, the main reasons for the formation of strong convective weather process in Guannan County on May 16, 2012 was analysed based on the weather situation and physical quantities. The results show that this strong convective weather process occurred under conditions of inversion layer, upper dry and low-level wet climate, high- level convergence and low-level divergence, and unstable stratification, and surface cold front was the major factor triggering this strong convection. Besides, radar echo played an important role in the short-term impending forecast during the development of the weather. The occurrence of a strong convective weather is related to cold air activity, so we should strengthen the monitoring of cold air activity, so as to improve our waming lev- el and service capability to forecast strong convective weather.

Prediction of Suitable Harvest Time in Aquaculture

A model is provided to predict the prawn’s harvest in aquaculture through analytical research in agrometeorology, mathematical statistics, synoptic meteorology and et al. It is found out that the Benefit Analysis of the Best Harvest is one of the most ideal ways. The models for the breeding objects, climate prediction and analysis of market quotation should be set up and perfected continuously. Only when the dynamic numerical simulation of the growth is accurate and the short-term weather forecast and the market quotation are reliable, will the suitable harvest time be predicted precisely. We used to write this paper with the foundation on ideologies.

Impact of Multi-Scale Oscillations at High and Low Latitudes on Two Persistent Heavy Rainfall Events in the Middle and Lower Reaches of the Yangtze River

To investigate the multi-scale features in two persistent heavy rainfall （PHR） events in the middle and lower reaches of the Yangtze River （MLRYR） in June of 1982 and 1998, this study examines the impact of multi-scale oscillations in the north and south of 30°N on the PHR events by performing sensitivity experiments with the Weather Research and Forecast （WRF） model. It is found that the 60-day low- pass perturbation made a trivial contribution to the MLRYR precipitation during the PHR event in 1982. This PHR event resulted mainly from the combined effects of 30-60-day oscillation at low latitudes and 10-30-day oscillation at both high and low latitudes. The southwesterly anomalies associated with the 30- 60-day anticyclonic anomaly over the northwestern Pacific facilitated moisture transport from the ocean to the MLRYR and enhanced the low-level convergence and ascending motion in the MLRYR. This similarly occurred in the 10-30-day oscillation as well. Moreover, the 10 30-day anomalies at high latitudes played a role in strengthening the large-scale low-level convergence over the MLRYR. The PHR event in 1998 was mainly related to the 60-day oscillation at both high and low latitudes and 30-60-day oscillation at low latitudes. The 60-day low-pass filtered anomalous cyclone at high latitudes in the north of 30°N contributed to the development of low-level convergence and ascending motion in northern MLRYR while the anomalous anticyclone at low latitudes in the south of 30°N not only increased the moisture in the MLRYR but also preconditioned the dynamical factors favorable for PHR over the whole area. The 30-60-day perturbations located north and south of 30°N worked together producing positive moisture anomaly in the MLRYR. In addition, the anomalous circulation in the south of 30°N tended to favor the development of ascending motion and low-level convergence in the MLRYR.

Advances in Ecological Applications of Fengyun Satellite Data

In recent years,the remote sensing based on meteorological satellite observations has become an important tool for assessing global ecological conditions.Since the early 2000,Fengyun(FY)satellite data have been widely used to derive the key parameters of ecological environment in China.An integrated earth-observation system has been developed in China through using FY satellite data,including retrievals the key ecological parameters as well as to constructions of long-term data records of vegetation index,land surface temperature,net primary production,vegetation health index,and so on.Considerable progress has thus been made in the application and service for prevention of air pollution,management and control of ecological redline,ecological monitoring for the Belt and Road Initiative,and assessment of ecological environment for human settlement.In order to monitor the ecological parameters in real time and with a full dynamic coverage,it is necessary to improve the technology in application of ecological remote sensing from meteorological satellites,and further enhance the ecological meteorological service.

Comparison of the Multi-Scale Features in Two Persistent Heavy Rainfall Events in the Middle and Lower Reaches of Yangtze River

Two persistent heavy rainfall（PHR） events in the middle and lower reaches of Yangtze River（MLYR）occurring in June 1982 and 1998 are studied in this paper.Though both events happened in the Meiyu season,their large-scale background and developing processes were quite different.During the PHR event in 1982,the Lake Baikal area was occupied by a strong westerly trough and the western Pacific subtropical high（WPSH） was stronger and more westward-extending than the normal years.Under such a condition,the cold dry air and warm moist air were continuously transported to the MLYR and favored the PHR there.For the event in 1998,the WPSH was similar to that in 1982,while the westerly trough in the Lake Baikal area was comparatively weak and a shortwave trough situating in East China contributed to advect cold dry air to the MLYR.It is found that the high-latitude trough was closely related to the 1030-day low-frequency oscillation while the anomaly of WPSH was linked with the combined effect of both30 60- and 10 30-day low-frequency oscillations in the PHR event in 1982.By contrast,the 60-day low-pass perturbation demonstrated positive impact on the westward extension of WPSH and development of the Baikal trough while the 30 60-day oscillation played a role in strengthening the shortwave trough in East China and the WPSH in the case of 1998.Though the low-latitude 30 60-day oscillations contributed to the intensification and westward extension of the WPSH in both PHR events,their evolution exhibited evident differences.In the 1982 case,the 30 60-day anomalies originated from the western Indian Ocean were much more like the Madden Julian Oscillation,while its counterpart in the 1998 case was much more similar to the first mode of the boreal summer intraseasonal oscillation.

EFFECTS OF THREE KINDS OF PHYSICAL PROCESSES ON TYPHOON INTENSITY

This paper designs three quasi-geostrophic barotropic models with a radial/horizontal grid length being 2 kin,one in the polar coordinates,one on a stationary typhoon circulation condition and another on a non-stationary typhoon circulation condition in the Cartesian coordinates,to investigate the effects of azimuthal and radial linear advections,and nonlinear advection on the inward propagation of mesoscale vorticity and the changes of typhoon intensity.Results show that the azimuthal linear advection may result in the formation of spiral vorticity bands;the radial linear advection in a certain parameter set is able to transfer vorticity inwards,leading to a slight enhancement of typhoon;the nonlinear advection of perturbation vorticity on a stationary typhoon circulation condition may transfer more vorticities inwards,thus resulting in a distinct enhancement of typhoon;and the nonlinear advection on a non-stationary typhoon circulation condition possesses duality,i.e.on the one hand,the advection increases the vorticity of inward propagation,thus favorable to the intensification of typhoon,and on the other hand,in the inward propagation process of vorticity the originally concentric and axisymmetric structure of typhoon basic flow is damaged,and a complex flow pattern forms,which in turn tends to weaken the circulation of typhoon.At last the paper discusses the possible applications of those results in typhoon intensity prediction.

ANALYSIS OF A STRONG MESOSCALE ENERGY FRONT CAUSING AN EXCEPTIONAL RAINSTORM

Under the outer-region effect of Typhoon Prapiroon (No.0012),an exceptional rainstorm occurred in northeastern Jiangsu Province from 0200 BT (Beijing Time) 30 August to 0800 BT 31 August 2000,which is an event of noticeable locality,abruptness,high intensity,a new record of rainfall measurement in history and very heavy damage caused,leading to the 24 h rainfall of 801.6 mm in County Xiangshui as the center of the rainstorm in the second quadrant of the outer region of the typhoon,i.e.,the northeastern Jiangsu Province,where a meso-β energy frontal zone is available at surface,serving as a weather system for generating and maintaining the exceptional rainstorm.Frontogenesis function used in diagnosing the production and development of the frontal zone displays different effects as follows:the deformation term plays a decisive role,the convergence term makes substantial contribution,but diabatic heating has some effect in the initial stage but less on the maintenance.Numerical study of a two-dimensional mesoscale equation shows that the driving around the frontal zone causes a vortex,whose ascending leg transports upwards warm and moist air from the high-energy area to such a level as to make it into cloud for precipitation and whose descending branch is liable for quick falling of raindrops and drawing cold air down onto surface for temperature drop there,allowing the frontal zone to be maintained and intensified,thus making rainfall intensity increased greatly.Comprehensive research indicates that when such a frontal zone is established the interactions among the convergent line,mesolow, mesohigh and driving-generated disturbance vortex in the neighborhood of the frontal zone are finally for the occurrence of the exceptional rainstorm.