Organizational Modes of Severe Wind-producing Convective Systems over North China

Severe weather reports and composite radar reflectivity data from 2010-14 over North China were used to analyze the distribution of severe convective wind（SCW） events and their organizational modes of radar reflectivity. The six organizational modes for SCW events（and their proportions） were cluster cells（35.4%）, squall lines（18.4%）, nonlinear-shaped systems（17.8%）, broken lines（11.6%）, individual cells（1.2%）, and bow echoes（0.5%）. The peak month for both squall lines and broken lines was June, whereas it was July for the other four modes. The highest numbers of SCW events were over the mountains, which were generally associated with disorganized systems of cluster cells. In contrast, SCW associated with linear systems occurred mainly over the plains, where stations recorded an average of less than one SCW event per year. Regions with a high frequency of SCW associated with nonlinear-shaped systems also experienced many SCW events associated with squall lines. Values of convective available potential energy, precipitable water, 0-3-km shear, and 0-6-km shear, were demonstrably larger over the plains than over the mountains, which had an evident effect on the organizational modes of SCW events. Therefore, topography may be an important factor in the organizational modes for SCW events over North China.

Feature Construction and Identification of Convective Wind from Doppler Radar Data

Convective wind is one of the common types of severe convective weather.Identification and Forecasting of convective wind are essential.In this paper,five kinds of features are firstly constructed from characteristics of typical convective wind-related echo phenomena based on Doppler radar data.The features include storm motion,high-value reflectivity,high-value velocity,velocity shear,and velocity texture.A severe convectiye wind(SCW)identification model is then built by applying the above features to the random forest model.With convective wind samples collected over 13 cities of China in June-August 2016,it is found that the probability of detection(POD)of SCW is 78.9%,the false alarm ratio(FAR)is 26.4%,and the critical success index(CSI)is 61.5%.For the convective wind samples that cary typical echo features,the POD,FAR,and CSI range from 89.4%to 99.3%,4.2%to 16.0%,and 76.4%to95.1%,respectively.Meanwhile,the POD and negative-case POD of samples without typical echo features are 66.8%and 85.4%,respectively.The experimental results demonstrate that the SCW identification model can classify nonSCW effectively,and performs better with SCW samples carrying typical echo features than without.

Initiation,organizational modes and environmental conditions of severe convective wind events during the warm season over North China

Based on the significant weather report,CG lightning,composite radar reflectivity,and ERA5 reanalysis data,we first studied the spatiotemporal distribution characteristics of four types(only severe convective wind(SCW);SCW and hail;SCW and short-duration heavy rainfall(SDHR);and SCW,hail,and SDHR)of convective weather events related to SCW during the warm season(May to September)from 2011 to 2018 in North China.Second,severe convective cases producing SCW were selected to statistically analyze the initiation,decay,lifetime,and organizational characteristics of convective systems.Finally,using ERA5 reanalysis data and conventional surface observation data,preconvective soundings were constructed to explore the differences in environmental conditions for initiating convective systems between SCW and non-SCW.The results indicate that mixed-type of SCW and SDHR events occur more frequently over plains,while other types of convective weather occur more frequently over mountains.The frequency peak of SCW occurs in June,while mixed convective weather peaks in July.The initiation time of convective systems is concentrated between 1000 and 1300 BST,with a peak at 1200 BST.Over mountains,the daily peaks of ordinary and significant SCW generally occur at 1700-1800 BST and 1600-1700 BST,respectively,while over plains,the peak of ordinary SCW typically lags behind that of mountains by 1-2 hours.Additionally,SCW systems are mainly initiated over mountains,with most lifetimes lasting 7–13 hours.Nonlinear convective systems produce the most SCW events,followed by trailing-stratiform convective systems.The convective available potential energy(CAPE),downdraft convective available potential energy,and the temperature difference between 850 and 500 hPa can all distinguish between SCW systems and non-SCW systems occurring over plains.Compared to non-SCW convective systems,SCW convective systems over mountains are more likely to occur in environments with less precipitable water,while SCW convective systems over plains are more likely to occur in environments with higher CAPE and stronger deep-layer wind shear.

Flows’ Similarities between Tornadoes or Cyclones Kinematics and Motions Resulting from Weather Phenomena Coupling Geostrophic Wind with Passive Convection

Tornadoes and cyclones, as is stated in numerous literary and audiovisual works dedicated to these out of balance physical systems, are two powerful and spectacular atmospheric phenomena whose vertical and horizontal profiles of winds and temperatures are not yet well known. Indeed, data and routine observations accumulated in the World Meteorological Organization (WMO) databases, regardless of their diversity and perfection of the instruments used to achieve these data (e.g. satellites, onboard cameras, wind profilers, ultra modern calculators, etc.), offer mind-blowing performances on the extent of damage caused by these disturbances, but information provided by these ground and space based observations will never allow access to real profiles of winds associated with tornadoes and cyclones both at the ground’s surface and aloft. The works recently carried out by C. Mbane Biouele allow us to discover that winds associated with tornadoes and hurricanes result from vectors addition of troposphere’s horizontal geostrophic winds and vertical movements associated with passive convection. Unfortunately, geostrophic wind and passive convection are two familiar meteorological phenomena described with much awkwardness and monumental mistakes by all scientific books written by authors who have remained loyal to Hadley principle which states (for centuries) that hot air is lighter than cold air. It is very important to know that C. Mbane Biouele’s very recent publications demonstrate that Hadley principle is not valid in the troposphere’s regions occupied by Ferrell cells. Indeed, it is urgent for the development of meteorology to highlight with great insistence to everyone that there is a Physics principle diametrically opposed to popular Hadley one which provides thermodynamic reasons of the formation of Ferrell cells. This Principle will be named Mbane Biouele Principe and be clearly stated in this paper.