Contrast Analysis of Two Low Vortices Weather Processes

Two cold vortex weather processes in Liaoning Province in June of 2006 were analyzed.In the process of low vortex of June 3,strong convection weather,such lightning storm and hailstone,came forth in most areas of Liaoning Province.White and bright cloud was shown in satellite nephogram.Bow echo and cyclonic circumfluence were shown in weather radar production.In the process of low vortex of June 14,strong precipitation weather came forth in most area of Liaoning Province.Based on the velocity field production of weather radar,the relative place of front and radar station can be judged.The weather situation and forecast were the main basis of short-term prediction.And satellite nephogram,weather radar,automatic weather station play important roles in the monitoring and short-term prediction of disaster weathers.

Shallow Analysis on the First Spring Soaking Rain Weather and Its Precipitation Enhancement Potential Forecast in Jinzhou Area in 2010

[Objective] The research aimed to study the first spring soaking rain weather and its precipitation enhancement potential forecast in Jinzhou area in 2010. [Method] From the weather situation characteristics, main influence system, forecast service, artificial precipitation enhancement operation and so on, the first spring soaking rain weather process in Jinzhou area in 2010 was summarized comprehensively. [Result] The weather situation characteristics of soaking rain were that the high-altitude cold air was weak, and the low-level warm wet airflow was obvious. The main influence systems were the high-altitude trough, the high-altitude shear line and the ground Mongolian cyclone. The ground inverted trough system advanced northward and got through with the same phase of Mongolian cyclone, which provided the certain energy and water vapor for the precipitation in Jinzhou area. It was one of key reasons for generating the soaking rain. The numerical forecast product played the certain guidance role in the forecast service work. The situation field forecast was accurate, but the precipitation forecast deviation was big. Therefore, the forecast service couldn’t depend on the numerical forecast product simply and totally, and should combine with the actual monitoring data to analyze and apply comprehensively. [Conclusion] The research played the safeguarding role in carrying out the large-scale artificial precipitation enhancement operation successfully in the whole area of Jinzhou.

Analysis on the Heavy Snow Weather Process in Benxi Area

[Objective] The aim was to study the formation and development of a heavy snow in Benxi area. [Method] Based on conventional meteorological data, the formation and development of a heavy snow in Benxi area from December 4th to 5th in 2009 were analyzed from the aspects of weather situation evolution and physical quantity field feature. [Result] The heavy snow was caused by upper trough and North China cyclone. In this process, there was upper level divergence and lower level convergence over Benxi area, and it was warm at low attitude and cold at high attitude; southwest jet at low attitude transported water vapor from Bohai Sea to eastern Liaoning, which provided good water vapor condition for snow, but it didn’t reach heavy snow due to inadequate ascending force. The development of Ural Mountains high ridge played an important role in the snow process and the strengthened high ridge moving northward was beneficial to the southward movement of cold air and deepening of upper trough. Analysis on physical quantity field could provide reference for predicting beginning and ending time and strength of heavy snow. [Conclusion] The study could provide basis for the forecast of heavy snow.

Study on Diagnosis Weather Process and Flight Impact of Heavy Snowfall in Northeast China “11/2021”

Based on ERA5 reanalysis data, the characteristics of weather situation, water vapor condition, dynamic uplift condition, energy condition, ice accumulation environment and flight effect of aircraft in the heavy snowfall process in northeast China from November 5 to 12, 2021 are analyzed. The results show that the heavy snowfall process in Northeast China is caused by the combination of Northeast China Cold Vortex, trough, low level frontal cyclone and cold front. Through the analysis of the physical field, it is found that the sufficient water vapor transport is from the south and the southeast, the convergence rising in the lower layer, divergence “pumping” in the upper layer, air flow rising in the vertical plane and a large amount of convection effective potential energy are all contributing to the heavy snowfall. The impact of heavy snowfall on flight mainly includes low visibility and ice accumulation. Water vapor flux, water vapor flux divergence, vertical velocity, potential temperature and convective effective potential energy can all be used as the judging indexes of heavy snowfall forecast.

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.

Analysis of Climatic Characteristics of Fog and Haze Weather in Shaoyang in the Past 60 Years and Its Forecast

Based on conventional observation data and NCEP reanalysis data at 10 national basic stations and reference stations of Shaoyang City during 1951-2014,300 cases of typical regional dense fog process appeared in the history were selected. From meteorological factors and weather situation,temporal-spatial distribution characteristics and trend change characteristics of dense fog in Shaoyang were analyzed. The results showed that（ 1） temporal-spatial distribution of dense fog in Shaoyang region was uneven,and interannual variability of fog days had large volatility and bad periodicity; dense fog days in Shaoyang region was obviously more in winter half year and less in summer half year. Dense fog was the most in November and the least in July. Dense fog mostly concentrated during 03： 00-09： 00; appearance time mostly concentrated during 05： 00-07： 30,and dissipation time mostly appeared after 08： 30. Dense fog appeared early and dissipated late in winter half year,and vice verse in summer half year.（ 2） Seen from meteorological factors,ground and 850 h Pa of wind velocity was generally 0-3 m/s,which was all small. Moreover,there existed temperature inversion from ground to 850 h Pa. Relative humidity on dense fog day was larger,and precipitation or cloudy day mostly appeared in prior day.（ 3） There were four kinds of ground weather situation forming dense fog： uniform pressure field type,cold and high pressure bottom type,cold and high pressure rear type,frontal type. Based on grasping change characteristics,rule and formation reason of dense fog,some forecast focus was found.

Prediction and Early Warning Indicators of Short-term Severe Convection Weather in Ulanqab City

Based on the disaster reports,NCEP2.5X2.5 reanalysis data and radiosonde data of 11 national stations in Ulanqab region from June to August during 2012-2017,the weather situation classification and warning indicators of thunderstorm and gale,hail and short-term heavy rainfall were studied.The results show that the cold vortex weather situation was easy to produce hail,and the falling area of severe convection could be found in the downstream of the cold vortex,the intersection area of jet stream at 200 and 500 hPa,and the wet area side of the 700 hPa main line.The cold trough type weather situation was easy to produce thunderstorm and gale,and the falling area of severe convection appeared on the right side of the upper jet stream axis,the left side of the lower jet stream axis,the wet side of the 700 hPa main line,and the east of the shear line at 700 hPa.The weather situation of the low trough and subtropical high type was dominated by short-term rainstorm,and the falling area of severe convection was on the right side of upper jet stream at 200 hPa,the left side of the low southeast jet stream,and the wet side of the 700 hPa main line.The warning index thresholds of the total index,the temperature change at 850-500 hPa with height,the height of 0 and-20℃layer,lifting condensation height,temperature dew point difference and mixing ratio were highly reliable.

Forecast Method of Ozone Concentration in Yulin City Based on Meteorological Conditions

Based on the monitoring data of ozone(O 3)concentration,conventional meteorological data and reanalysis products in Yulin City from 2018 to 2019,the weather situation of O 3 pollution was classified through case analysis and mathematical statistics.At 500 hPa,the weather situation was divided into continental high pressure type,subtropical high type and mixed type.At 850 hPa,it was divided into southwest air flow type,east air flow type and south air flow type.The correlation between meteorological element and O 3 concentration were analyzed,and factors with good correlation such as temperature,air pressure and wind speed were selected to establish regression equations.The fitting effect was good,and O 3 concentration could be objectively predicted.

Vertical Helicity Analysis of First Rainstorm at the Beginning of Meiyu in Hubei in 2009

By using the data in Hubei automatic rainfall station and NCEP 1°×1° global reanalysis data,the vertical helicity analysis on the rainstorm weather process which happened in Hubei Province during June 28-30 in 2009 was done.The results showed that the spatial and temporal evolution characteristic of vertical helicity could reflect well the occurrence time and the falling zone of strong precipitation in the situation that the strong vertical ascent movement in the whole layer stably maintained.The distribution of 700 hPa vertical helicity gradient big value area which was 6 h interval and the ∑θse(500+700+850) horizontal energy frontal zone superposition area both had the good directive significance for the falling zone of 6 h heavy precipitation.The zone where the heavy precipitation appeared had the configuration of positive vertical helicity in the low layer and the negative vertical helicity in the high layer.When the positive vertical helicity in the low layer was slightly higher than the negative vertical helicity in the high layer,it favored the generation of heavy rainstorm center.

Analysis on A Cold Flow Snowstorm in Yantai

On December 3-5,2008,a cold flow snowfall happened in Shandong Peninsula.The basic weather situation and environmental field were analyzed.The results showed that the terrain condition,water vapor's latent heat-exchange in Bo Sea,temperature differences between sea and land were very important elements in this process.

Study on Statistical Forecast Method for O_3 Concentration near the Ground in Pudong District of Shanghai Based on Meteorological Condition Analysis

[Objective] The research aimed to study statistical forecast method for O3 concentration near the ground in Pudong District of Shanghai based on meteorological condition analysis. [Method] Via observation and statistical analysis of the O3 concentration near the ground in Pudong District of Shanghai from 2006 to 2008, by considering meteorological condition, a kind of simple and practical new method suiting for forecast of the O3 concentration and pre-warning of the high-concentration O3 pollution event in whole year was established. [Result] Meteorological condition had obvious influence on O3 concentration near the ground. O3 concentration was the biggest in sunny day, followed by cloudy day. O3 concentration near the ground had typical seasonal change characteristics, and high value mainly happened in summer. Meteorological condition generating high-concentration O3 included sunny day, strong UV radiation, low relative humidity, high temperature and small wind speed, etc. By surveying historical weather chart, 10 kinds of main weather situations affecting Shanghai were summed. Under each weather situation, occurrence probability of the high-concentration O3 near the ground and average O3 concentration were conducted statistics. We found that occurrence probability of the high-concentration O3 was the biggest under northwest side of the subtropical high type, followed by internal type of the subtropical high. By introducing HPPI and WDI and comprehensively considering various meteorological factors, forecasting equation of the O3 concentration was established based on stepwise regression. The equation had good fitting effect and predictability on the daily maximum O3 concentration. [Conclusion] The method also could provide reference for O3 forecast in other areas.