Analysis of Rainstorm Process in South China from September 7 to 8, 2022

Based on the NCEP data of the United States, a rainstorm process in South China during September 7 to 8, 2022 was studied. Synoptic method is a qualitative and empirical forecasting method. The results show that: In early September 2022, the cold air behind the trough line from northeast China to North China can directly drive southward and invade South China from the east road. Typhoon Hinnamnor is located in the saddle field between the mainland subtropical high and the offshore subtropical high. It moves northward on the west side of the coastal subtropical high, affecting the Taiwan Island and the coastal areas of East China. During September 7-8, the wave trough of the 925 hPa Easterly wave was located near 110°E. Easterly jet existed in the southeast of South China. The center of the easterly jet was located to the east of Hainan Island, which could transport abundant water vapor from the sea surface to the sky over South China. The precipitable water in the whole layer of the atmosphere decreased from the southern coastal areas to the north, reaching more than 50 mm in southern China, of which most of the South China Sea, Hainan Island and parts of the western part of Guangdong Province exceeded 60 mm, providing sufficient water vapor supply. The circulation field with convergence at low level and divergence at high level is conducive to vertical uplift to form precipitation.

New Evidences on the Climatic Causes of the Formation of the Spring Persistent Rains over Southeastern China

The spring persistent rains（SPR）over southeastern China（SEC）are a unique synoptic and climatic phenomenon in East Asia.A former study has found that the southwesterly flow which lies on the southeastern flank of the Tibetan Plateau（TP）is one of the deflected westerly flows of the TP,and it is suggested to be the direct climatic cause of SPR.This study found that the southwesterly flow is also highly correlated with the sensible heating of the southeastern TP in interannual variability,in addition to having a high correlation in seasonal variability.These facts suggest that the thermal forcing of the TP is another important climatic cause of SPR.Numerical sensitivity experiments further prove that the mechanical and thermal forcings of the TP are the climatic causes of the formation of the SPR.On the other hand,the Nanling Mountains and Wuyi Mountains（NWM）over southeastern China not only increase the SPR precipitation amount evidently,but also make the SPR rain belt move to the south by blocking the strong southwesterly flow.

Analysis on a Regional Heavy Rainstorm Process in North Henan

[Objective] The research aimed to analyze a regional heavy rainstorm process in North Henan.[Method] Based on routine weather chart,rainfall station in county and town,satellite cloud chart,etc.,by using synoptic diagnostic method,formation reason of the regional heavy rainstorm weather in North Henan during 18-19 August,2010 was analyzed initially from large-scale circulation background,influence system,physical quantity field and terrain influence.[Result] The strong precipitation had obvious meso-scale characteristics.The main influence systems were ground meso-scale convergence line,shear line at the middle and low layers,low-level southwest jet.The low-level southwest jet transported sufficient water vapor for generation of the heavy rainstorm.The ground converge line increased convergence ascending movement and water vapor convergence.Atmospheric divergence convergence center at the low layer was just in North Henan.Strong rise zone of the vertical velocity was also in North Henan.It provided sufficient dynamic condition for rainstorm generation.Generation,development and movement of the ground meso-scale convergence line had good indications for occurrence times and falling zones of the rainstorm and short-time strong precipitation.The big-value zones of K index and θse at the low layer both presented Ω distribution at the vertical direction,which had indicative significance for strong precipitation forecast.The strong precipitation center corresponded with fork horn terrain,and orographic rain characteristics were obvious.[Conclusion] The research provided reference basis for forecast of this kind of rainstorm.

Design and Realization of Similar Report System of Moderate Rain,Heavy Rain and Rainstorm in Guyuan City

[Objective] The aim was to design and promote similar report system of moderate rain, heavy rain and rainstorm in Guyuan City. [Method] As C#. Net2005 development platform and based on MSSQLSEVER2005 database system, the upper air circulation during moderate rain, heavy rain and rainstorm from May to September since 1960, taking 500 hPa, 700 hPa and ground situation as complement, the similar height of 500 and 700 hPa were calculated. [Result]The system is set to be personal and template. The system only needs to be set for once. If the in- stallation is changed, the system doesn＇t need to change parameters. The system would automatically read the parameters and make it easy for the businessman to use. Meanwhile, it solves the problem of storing abundant data. Considering the promotion and application, the system is designed to be universal and portable, [ Conclusion] The system makes uP the Oossibilitv of mis-reoortina the moderate rain. heaw rain and rainstorm.

Study on Temporal-spatial Distribution of Heavy Rain and Rainstorm in Different Functional Areas of Chongqing

To discuss response ability of five functional areas to rainstorm flood in Chongqing,by taking 8 districts（ counties） as research object,monthly occurrence times of heavy rain and rainstorm in different functional areas over the years and appearance month of the maximum rainfall were conducted statistics. Results showed that frequency distribution of heavy rain in whole year in different functional areas was different,but it was similar in the same functional zone. Temporal-spatial distribution of rainstorm was more independent,and there were different performances in various districts of each functional area. In urban functional core area and urban functional expansion area,rainstorm times was more,and the maximum precipitation was larger. In urban development new district,rainstorm times and the maximum precipitation were relatively smaller in whole Chongqing. In ecological conservation development area of northeast Chongqing,rainstorm duration was longer,and we needed prevention and control during June- September. In ecological protection area of southeast Chongqing,although rainstorm occurrence times was the most in Chongqing,the heavy rainstorm was less.

Repair the house before it rains

Many people like making predictions at the end of a year. However, late October to January is not only a time for predictions, it is also when economists send out early warnings about emerging problems. Some of their comments are revealing. For instance, one problem resulting from a lack of government reform is posing a hindrance to the economy’s progress.

Impacts of Cloud-Induced Mass Forcing on the Development of Moist Potential Vorticity Anomaly During Torrential Rains

The impacts of cloud-induced mass forcing on the development of the moist potential vorticity (MPV) anomaly associated with torrential rains are investigated by using NCEP/NCAR 1? × 1? data. The MPV tendency equation with the cloud-induced mass forcing is derived, and applied to the torrential rain event over the Changjiang River-Huaihe River Valleys during 26–30 June 1999. The result shows that positive anomalies are located mainly between 850 hPa and 500 hPa, while the maximum MPV, maximum positive tendency of the MPV, and maximum surface rainfall are nearly collocated. The cloud-induced mass forcing contributes to the positive tendency of the moist potential vorticity anomaly. The results indicate that the MPV may be used to track the propagation of rain systems for operational applications.

A QUANTITATIVE STUDY FOR ABNORMAL FREEZING RAINS AND SNOWSTORMS IN SOUTHERN CHINA IN EARLY 2008

A quantitative diagnosis is carried out for the upward branch of a local meridional circulation over southern China(SC) during the abnormal snowstorms with severe freezing rain from 10 January to 3 February 2008.The diagnostic study shows that the upward branch is mainly associated with the zonal advection of westerly momentum and meridional temperature advection instead of the latent heating(which is commonly the dominant factor in many other storm cases).The corresponding weather analyses indicate that(1) the zonal advection of westerly momentum represents the effect of the upper-level divergence on the anticyclone-shear side in the entrance of a 200 hPa westerly jet with a westward deviation from its climatological location over southwestern Japan;(2) the meridional temperature advection represents the interaction between the mid-lower layer(850 to 400 hPa) warm advection over SC(ahead of temperature and pressure troughs with the latter trough deeper than the former in the Bay of Bengal) and cold advection over north China(steered by an underlying flow at 500 hPa);(3) the relatively weak vapor transport(compared to that of spring,summer and autumn) from the Bay of Bengal and the South China Sea to SC and the existence of a temperature inversion layer in the lower troposphere over SC diminish the effect of latent heating.With the significant increase of vapor transport after 24 January,the role of latent heating is upgraded to become the third positive contributor to the upward branch over SC.

Analysis of Deep Convective Towers in a Southwest-Vortex Rainstorm Event

The structure and organization of the extreme-rain-producing deep convection towers and their roles in the formation of a southwest vortex(SWV)event are studied using the intensified surface rainfall observations,weather radar data and numerical simulations from a high-resolution convection-allowing model.The deep convection towers occurred prior to the emergence of SWV and throughout its onset and development stages.They largely resemble the vortical hot tower(VHT)commonly seen in typhoons or hurricanes and are thus considered as a special type of VHT(sVHT).Each sVHT presented a vorticity dipole structure,with the upward motion not superpose the positive vorticity.A positive feedback process in the SWV helped the organization of sVHTs,which in turn strengthened the initial disturbance and development of SWV.The meso-γ-scale large-value areas of positive relative vorticity in the mid-toupper troposphere were largely induced by the diabatic heating and tilting.The strong mid-level convergence was attributed to the mid-level vortex enhancement.The low-level vortex intensification was mainly due to low-level convergence and the stretching of upward flow.The meso-α-scale large-value areas of positive relative vorticity in the low-level could expand up to about 400 hPa,and gradually weakened with time and height due to the decaying low-level convergence and vertical stretching in the matured SWV.As the SWV matured,two secondary circulations were formed,with a weaker mean radial inflow than the outflow and elevated to 300-400 hPa.

Evolution of Instability before and during a Torrential Rainstorm in North China

NCEP-NCAR reanalysis data were used to analyze the characteristics and evolution mechanism of convective and symmetric instability before and during a heavy rainfall event that occurred in Beijing on 21 July 2012.Approximately twelve hours before the rainstorm,the atmosphere was mainly dominated by convective instability in the lower level of 900-800 hPa.The strong southwesterly low-level jet conveyed the moist and warm airflow continuously to the area of torrential rain,maintaining and enhancing the unstable energy.When the precipitation occurred,unstable energy was released and the convective instability weakened.Meanwhile,due to the baroclinicity enhancement in the atmosphere,the symmetric instability strengthened,maintaining and promoting the subsequent torrential rain.Deriving the convective instability tendency equation demonstrated that the barotropic component of potential divergence and the advection term played a major role in enhancing the convective instability before the rainstorm.Analysis of the tendency equation of moist potential vorticity showed that the coupled term of vertical vorticity and the baroclinic component of potential divergence was the primary factor influencing the development of symmetric instability during the precipitation.Comparing the effects of these factors on convective instability and symmetric instability showed some correlation.

Does Rapid Urbanization Trigger Significant Increase of Cumulative Heavy Rains in China?

Severe disasters caused by extreme precipitation events have attracted more and more attention. The relationship between climate change and extreme precipitation has become the hottest scientific frontier issue. The study of daily torrential rain observations from 659 meteorological stations in China from 1951 to 2010 shows that rapid urbanization may have triggered a significant increase in heavy rains in China. It reached following conclusions: China’s interdecadal heavy rainfall amount,rainy days and rain intensity increased significantly,with an increase of 68. 71%,60. 15% and 11. 52%,respectively. The increase in the number of stations was 84. 22%,84. 22% and 54. 48%,respectively. It showed time change of " rapid-slow-rapid increase" and spatial change of gradual increase from southeastern coast to central China,southwest,north China,and northeastern regions. Rapid urbanization factors,including secondary industry output( GDP2),urban population ratio( UP),annual average haze days( HD),are likely to be the main causes of the increase in heavy rains in China. Their explanations of the variance of heavy rainfall amount( HRA),rainy day( RD) and rain intensity( RI) in China reached 61. 54%,58. 48% and 65. 54%,respectively,of which only the explanation of variance of heavy rainfall amount,rainy days and rain intensity was as high as 25. 93%,22. 98%and 26. 64%,respectively. However,explanation of variance of climatic factors including WPSH( West Pacific Subtropical High),ENSO( El Ni1 o-Southern Oscillation) AMO( Atlantic Interdecadal Oscillation),and AAO( Antarctic Oscillation) was only 24. 30%,26. 23%,and 21. 92%,respectively. Compared with the rapid urbanization forcing factor,the impact of these climatic factors was only one third of the former. The panel data of China’s county-level total population and annual average of visibility days were significantly correlated with China’s interdecadal heavy rainfall amount,rainy days and rain intensity. Their spatial correlation coefficient increased gradually from 1951-1960 to 2001-2010,that is,the total population of the county level increased from 0. 35,0. 36,and 0. 40 to 0. 54,0. 55,and 0. 58,respectively.The annual average of visibility days increased from 0. 36,0. 38,and 0. 48 to 0. 55. 0. 57,0. 58,further indicating that rapid urbanization triggered a significant increase in interdecadal large-area heavy rains in China.

Modal Analysis of Linear Mesoscale Convective System in Fujian Heavy Rainstorm

This paper uses the daily precipitation observation data and Doppler weather radar observation data from 2017 observatories and regional automatic stations in Fujian, China from 2009 to 2015. The characteristics of formation mode, organization mode, moving direction and duration of linear mesoscale convective system during non-typhoon continuous rainstorm in Fujian were analyzed. This paper gives the definition of linear mesoscale convective systems, trailing and parallel mesoscale convective systems. The above characteristics of the linear mesoscale convective system during the continuous heavy rain in Fujian differ greatly from the non-sustained heavy rain process: The linear mesoscale convective system in the continuous heavy rain in Fujian is mainly constructed later, and the trailing and parallel mesoscale convective system is conducive to the occurrence of continuous heavy rain in Fujian. The moving direction of the linear mesoscale convective system and convective monomer is mainly in the east direction, and the system duration is mostly 4 - 10 hours. The formation time of the monomer to form a linear convection time is mainly 1 - 3 hours, which is 2 hours earlier than the organization process of the general linear mesoscale convective system. The linear convective system formed to a dead time of an average of 5 hours, slightly longer than the general linear mesoscale convective system.

The Mid-Term Model Forecast Test of North China Rainstorm from July 19th to 20th, 2016

Heavy rain is a kind of severe weather, often causing floods and serious soil erosion, leading to engineering losses, embankment rupture and crop flooding and other significant economic losses. Especially for some low-lying terrain areas, rainwater cannot quickly vent caused by farm water and soil moisture being too saturated, so it will cause more geological disasters. This article combines live and forecast data, aiming at the results of the mid-rainstorm forecast in North China during the period of 7.19-2016, and compares with the actual situation of rainstorm. We carry out the mid-term forecast of the rainstorm. The atmosphere is a kind of medium with various fluctuation phenomena, and its physical properties and changes are studied by the analysis of volatility which is an important research method. It is important to improve the accuracy of such severe weather forecasting rainstorms and to take precautionary measures in a timely manner to minimize the losses caused by rainstorms.

Mollusk Species Richness on the Rocky Shores of the State of Guerrero, Mexico, as Affected by Rains and Their Geographical Distribution

Natural processes in ecosystems shows significant variations in species richness with regular cycles that can be altered by natural or anthropogenic activities;the present research was in order to understand on some of these variations. The objectives were: 1) determine the species richness of rocky intertidal mollusks;2) track their geographical distribution at State level;and 3) determine the changes in species richness as a result of rainfall on an annual cycle. For these purposes it was sampled in March, June, September and December 2005, the sampled area was 20 m2for each collecting site;the sampling unit was a PVC rectangle frame one by two meter per side. The mollusks found within the sampling units were collected, identified and counted. The species distribution was analyzed by sites and regions, considered species richness per season, and the distributional patterns by rainy season historical records. A total of 62 mollusks species were found, its richness associated with substrate stability and wave intensity on each site, Gastropods had the highest species richness. When analyzing the regional distribution and sites, it was found a pattern of species richness roughly constant in the proportion of species with wide distribution (generalists) versus those of restricted spatial representation (specialists). Gastropods had the highest number of species with restricted spatial representation. Seasonal rainfall differences did not quantitatively altered on the overall the species of mollusks in the rocky intertidal sampled zone however, in the analysis per Class, Gastropoda indicated changes in species richness influenced by rainfall, which were not observed in Bivalvia and Polyplacophora, suggesting that those changes might depend on adaptive processes or the lack of adaptation of gastropod species to the characteristics of the rocky intertidal habitat.

Analysis on the Radar Echo's Characteristics of One Severe Rainstorm in Central Guangxi

[Objective] The aim was to analyze radar echo characteristic of a heavy rainstorm in central Guangxi in June, 2010. [Method] Using conventional observations and automatic stations, Doppler radar and other data, a severe rainstorm in central of Guangxi which occurred on 31 May to 1 June 2010 was analyzed. The characteristics of weather radar data were analyzed to reveal the characteristics of radar echo during the heavy precipitation process. [ Result] The heavy rainstorm had gone through many singular wind storms towards MCS variation. The existence of ultra-sin- gular and ＂train effect＂ was the main reason of the heavy rainstorm. The results showed that during the heavy rainfall experienced an evolution process from multi-cell storm to MCS, and found that super cell and the ＂train effect＂ was the major reason which caused this torrential rain. The echo centroid of multi-cell storm stretching along its moving reverse order was the key factor which maintained the heavy rain. Analysis also found that the average echo intensity had a good relationship with rainfall. Strong echoes were in quasi-stationary state for a long time and was favorable heavy rain. In the diameter velocity diagram, mesoscale convergence line, the adverse wind regions and the mid-cyclone were the important basis to determine producing and keeping heavy rainfall. Radar wind profile can reflect the configuration of layers of wind conditions, and it was an effective tool to determine whether the trough was in transition or not. [ Conclusion] The study provided reference for the short-term and nowcasting report.

Simulation of thermal and humid environment of rural residence envelope inner surface during the plum rains season in Changsha China

The Plum Rains Season(PRS)has the typical characteristics of outdoor air temperature dramatic changes and high air humidity in the hot summer and cold winter region in China.Even if the indoor heat source and moisture production is constant,when the outdoor air temperature rises rapidly during high air humidity PRS,the build-ing envelope temperature heats up much more slower than the indoor air temperature and therefore the wall surface temperature is lower than the indoor air dewpoint which leads to condensation phenomenon,resulting in deterioration of insulation performance,mouldy walls,deterioration of indoor air quality.At present,there is a lack of research on the factors affecting condensation in rural residence during PRS.This paper evaluates the impact of occupants’habit of window opening modes and building construction parameters on the building envelope surface condensation in Changsha during PRS.Using Designer’Simulation Toolkit(DeST)simulated and analysed the impact of key parameters such as window-to-wall ratio,exterior wall reflectivity,window opening mode(open/close),and external wall insulation on the building indoor thermal and humid environment.The condensation risk X is proposed to evaluate the condensation possibility on the building envelope’s inner sur-face.The results show that from the perspective of anti-condensation:The rural residential building in Changsha should balance the window-wall ratio against better natural lighting;Keeping windows closed during PRS can effectively alleviate the condensation problem while the insulation in the external wall layer could aggravate the condensation.

Mesoscale and Microphysical Characteristics of a Double Rain Belt Event in South China on May 10–13,2022

A second rain belt sometimes occurs ahead of a frontal rain belt in the warm sector over coastal South China,leading to heavy precipitation.We examined the differences in the mesoscale characteristics and microphysics of the frontal and warm sector rain belts that occurred in South China on May 10–13,2022.The southern rain belt occurred in an environment with favorable mesoscale conditions but weak large-scale forcing.In contrast,the northern rain belt was related to low-level horizontal shear and the surface-level front.The interaction between the enhanced southeasterly winds and the rainfall-induced cold pool promoted the persistent growth of convection along the southern rain belt.The convective cell propagated east over the coastal area,where there was a large temperature gradient.The bow-shaped echo in this region may be closely related to the rear-inflow jet.By contrast,the initial convection of the northern rain belt was triggered along the front and the region of low-level horizontal shear,with mesoscale interactions between the enhanced warm-moist southeasterly airflow and the cold dome associated with the earlier rain.The terrain blocked the movement of the cold pool,resulting in the stagnation of the frontal convective cell at an early stage.Subsequently,a meso-γ-scale vortex formed during the rapid movement of the convective cell,corresponding to an enhancement of precipitation.The representative raindrop spectra for the southern rain belt were characterized by a greater number and higher density of raindrops than the northern rain belt,even though both resulted in comparable hourly rainfalls.These results help us better understand the characteristics of double rain belts over South China.

Temporal and Spatial Distributions of the Spring Persistent Rains over Southeastern China

The spring persistent rains （SPR） over southeastern China （SEC） is a synoptic and climatic phenomenon that is unique in East Asia. Sufficient evidence proves that it results from the mechanical and thermal effects of the giant Tibetan Plateau （TP）, but its temporal span and spatial distribution are not clear at present. A climatological analysis of the NCEP/NCAR circulation and sensible heat data shows that at the 13th pentad of the solar year （lst pentad of March） there are remarkable increases in the sensible heating over the main and southeastern part of the TP, the southwesterly velocity over the southeastern flank of the TP and SEC, and rainfall over SEC, indicating the onset of the SPR. However, after the 27th pentad of the solar year （3rd pentad of May）, these variables, except for the sensible heating over the main part of the TP, decrease rapidly. The ridge line of the subtropical high in the mid-low troposphere over the South China Sea （SCS） slopes northward to the SCS and the SCS monsoon instead of southward as before breaks out, indicating the end The rain belt center over SEC shifts of the SPR. Hence, it is reasonable to define the SPR temporal span from the 13th to 27th pentad of the solar year. Data analysis and numerical sensitivity experiments show that, although the warm and cold airs converge at about 30°N in the SPR period, the distribution and intensity of the SPR rain belt are obviously influenced by the topography of the Nanling and Wuyi Mountains （NWM）. The mountains can block and lift cold and warm airs, strengthening frontogenesis and rainfall. As a result, the axis of the SPR rain belt is superposed over that of the mountain range. Accordingly, the spatial distribution of the SPR extends over most of the SEC, more specifically, to the south of the middle and lower reaches of the Yangtze River （30°N）, and to the east of 110°E.

Relationship Between the Western Pacific Subtropical High and the Subtropical East Asian Diabatic Heating During South China Heavy Rains in June 2005

Based on the daily NCEP/NCAR reanalysis data,the position variation of the western Pacific subtropical high（WPSH） in June 2005 and its relation to the diabatic heating in the subtropical East Asia are analyzed using the complete vertical vorticity equation.The results show that the position variation of the WPSH is indeed associated with the diabatic heating in the subtropical East Asian areas.In comparison with June climatology,stronger heating on the north side of the WPSH and relatively weak ITCZ（intertropical convergence zone） convection on the south side of the WPSH occurred in June 2005.Along with the northward movement of the WPSH,the convective latent heating extended northward from the south side of the WPSH.The heating to the west of the WPSH was generally greater than that inside the WPSH,and each significant enhancement of the heating field corresponded to a subsequent westward extension of the WPSH.In the mid troposphere,the vertical variation of heating on the north of the WPSH was greater than the climatology,which is unfavorable for the northward movement of the WPSH.On the other hand,the vertical variation of heating south of the WPSH was largely smaller than the climatology,which is favorable for the anomalous increase of anticyclonic vorticity,leading to the southward retreat of the WPSH.Before the westward extension of the WPSH in late June 2005,the vertical variation of heating rates to（in） the west（east） of the WPSH was largely higher（lower） than the climatology,which is in favor of the increase of anticyclonic（cyclonic） vorticity to（in） the west（east） of the WPSH,inducing the subsequent westward extension of the WPSH.Similar features appeared in the lower troposphere.In a word,the heating on the north-south,east-west of the WPSH worked together,resulting in the WPSH extending more southward and westward in June 2005,which is favorable to the maintenance of the rainbelt in South China.

Temporal Variations of the Spring Persistent Rains and South China Sea Sub-high and Their Correlations to the Circulation and Precipitation of the East Asian Summer Monsoon

National Meteorological Information Center （NMIC） rainfall data and NCEP/NCAR daily circulation reanalysis data are employed to establish the onset-pentad time index of the spring persistent rains （SPR） and the decay-pentad time index of the South China Sea （SCS） sub-high. These indexes are used to study the relationship between the factors in SPR period and their relations to the circulation and precipitation of the East Asian summer monsoon （EASM）. Results show that, the summer rainfall over southeastern China decreases when SPR onset is late. For then EASM strengthens and the cyclonic circulation around the Tibetan Plateau （TP） strengthens, which makes abnormal anti-cyclonic circulation （cyclonic convergent circulation weakens） appear over southeastern China. When the decay of SCS sub-high delays, abnormal flood prevails over the middle and lower reaches of the Yangtze River （MLYR） and to the south. That is mainly caused by EASM weakening while SCS sub-high strengthening, then the abnormal southwesterly over South China and the abnormal northerlies of anti-cyclonic circulation around the TP converge over the Yangtze Valley. The two indexes have high correlations with multivariate ENSO index （MEI） in March, indicating that the climate abnormity in East Asia is related to global climate abnormity tightly. The two time indexes are independent of each other, which is favorable for the prediction of the anomalies of the circulation and precipitation of EASM. From this point of view, we must take the global climate background into account when we analyze and predict the East Asian summer circulation and precipitation.