Abstract:To understand the variation patterns of ground temperature,this study analyzed the charac-teristics of 0 cm ground temperature and its climatic influencing factors in Zhaoqing urban area over the past 64 years(1960-2023)based on data from the Gaoyao Meteorological Station,including 0 cm ground tem-perature,air temperature,precipitation,and sunshine duration.Methods such as linear trend analysis,cor-relation analysis,and Mann-Kendall test were employed.The results indicate that:(1)Over the past 64 years,the annual and seasonal average 0 cm ground temperatures in Zhaoqing urban area showed a signifi-cant decreasing trend(P＜0.01)in all seasons except winter,with the climate tendency rates following the order of summer＞autumn＞annual＞spring＞winter in terms of significance.(2)The interannual var-iation of the annual average 0 cm ground temperature in Zhaoqing urban area exhibited multiple abrupt change points(P＜0.01),mainly concentrated between 1990 and 2005.(3)At annual,seasonal,and monthly scales,the 0 cm ground temperature showed certain correlations with air temperature,precipitation,and sunshine duration,with the correlation strengthening as the time scale decreased.This study provides valuable insights into the long-term changes of ground temperature and its climatic drivers,contributing to a better understanding of regional climate dynamics.

Abstract:To enhance the forecast and early warning capabilities for winter hazardous weather in the mountainous area of northern Guangdong,this study analyzed a low-temperature freezing rain and snow event in early 2022 using hourly rainfall data from ground meteorological observation stations,feedback from mete-orological informants,and FNL reanalysis data.The results show that this event was characterized by heavy cumulative rainfall,widespread freezing in mountainous areas,and a long duration.During the event,the atmospheric circulation pattern remained stable,with a strong blocking high over Eurasia and active southern branch troughs near 90°E,combined with the continuous influence of cold air from the surface.The 700 hPa level was identified as the key layer for this event,as precipitation trends were closely related to the meridio-nal wind speed at this level,and moisture flux convergence was also concentrated at 700 hPa.A deep melt-ing layer,approximately 2 km thick,was observed near the 850-700 hPa level,leading to widespread freezing rain in Shaoguan.Short-lived sleet occurred from the night of the 19th to the morning of the 20th.Forecasting precipitation types requires high-frequency monitoring of vertical temperature distribution through multiple methods and integrating real-time observations to adjust short-term forecasts.

Abstract:To ensure safe operation and improve runway utilization after the airport's completion,an a-nalysis of the wind condition characteristics at the Genghe North preliminary site for Foshan New Airport was conducted.The results show that the average annual wind speed during the observation period at the Genghe North preliminary site was 1.7 m·s-1,with monthly averages ranging between 1.5 and 2.0 m·s-1.Ex-treme wind speeds of up to 32.0 m·s-1 have occurred due to typhoon influences.The predominant wind di-rections are northeast(NE-NNE),followed by southwest(SW-SSW).Winds with speeds below 3 m·s-1 account for 89.69%of the wind speed frequency,while those below 6.5 m·s-1 account for 99.51%.Wind speed and direction have minimal impact on the runway.The wind load percentage with crosswind speeds not exceeding 6.5 m·s-1 is 99.74%,meeting runway operational requirements.

Abstract:To improve the accuracy of surface wind speed forecasts,this study utilizes the 10 m wind speed forecast products from the European Centre for Medium-Range Weather Forecasts(ECMWF)numeri-cal weather prediction model with a resolution of 0.125°(referred to as the EC model)and the CMA-GD(R3)regional numerical weather prediction model of the China Meteorological Administration with a resolu-tion of 0.03°for South China(referred to as the CMA-GD model).Based on the 2-minute average wind speed observations from automatic weather stations in Guangdong Province from May to July 2023,a method combining error statistical analysis and inverse proportional weighting was applied to evaluate and correct the 0-24 hour forecasts of 10 m wind speed from these models.The results show that in terms of the accuracy of 10 m wind speed forecasts,both models perform better in coastal areas of Guangdong Province than in in-land areas.Among them,the EC model exhibits better forecast performance,with forecast errors ranging from 0 to 2.0 m·s-1,and most errors are less than 1.5 m·s-1.In contrast,the CMA-GD model has rela-tively larger forecast errors,generally exceeding 1.5 m·s-1 and reaching up to 3.0 m·s-1.After correc-tion,the forecast errors of the EC model for 10 m wind speed can be reduced to 0-0.3 m·s-1,while those of the CMA-GD model are reduced to 0-0.4 m·s-1,effectively improving the forecast accuracy of both models for 10 m wind speed.

Abstract:The year 2025 in Guangdong province featured an increased frequency of high-temperature days,more intense extreme precipitation events,a record high number of typhoons and tornadoes,and a his-torically low count of hazy days.The annual mean temperature was 22.6℃,which is 0.5℃above the cli-matological average.The average number of high-temperature days reached 28.3,exceeding the norm by 6.8 days.Total annual precipitation averaged 1 879.7 mm,representing a 4%increase relative to the cli-matological mean.The flood season commenced later than usual and was marked by severe precipitation ex-tremes,including a flood event in Huaiji County that exceeded a 1-in-100-year return level.The first ty-phoon of the year arrived earlier than average.Overall,15 tropical cyclones made landfall or significantly impacted the province,setting a historical record.Among these,Typhoons Ragasa and Matmo severely af-fected western Guangdong.A total of 43 tornadoes were recorded for the year,with a notable cluster occur-ring in Zhanjiang City,representing the highest annual count on record.Unusual dust weather was observed in April.Meteorological droughts developed periodically,contributing to heightened forest fire risks during autumn and winter.Cold air activity was intermittently strong.The number of hazy days was the lowest since systematic observations began.Overall,the climatic conditions in Guangdong for 2025 were poor.

Abstract:To reveal the characteristics and patterns of short-term heavy precipitation in Nanhai Dis-trict,Foshan City,this study conducted a spatiotemporal analysis based on hourly precipitation data from 103 automatic weather observation stations in the district from 2013 to 2024.The results indicate that over the past 12 years,a total of 11392 station occurrences of short-term heavy precipitation were recorded in the district,with an annual average of 949 occurrences.The highest frequency occurred in 2024(1716 occur-rences),while the lowest was in 2013(591 occurrences).Short-term heavy precipitation mainly concentrat-ed during the flood season(April to September).During the early flood season,under the combined influ-ence of the southwest monsoon and topography,the intersection area of Shishan Town,Dali Town,and Guicheng Subdistrict,as well as the border between northeastern Shishan Town and northwestern Lishui Town,were frequent regions for short-term heavy precipitation.In the late flood season,influenced by tropi-cal weather systems and the urban heat island effect,short-term heavy precipitation exhibited distinct local characteristics,with high-frequency centers being more dispersed.The peak period for short-term heavy pre-cipitation occurred from afternoon to evening.During the early to midnight hours,short-term heavy precipita-tion was more likely to occur in the eastern and southern towns and subdistricts of Nanhai District in the early flood season,whereas in the late flood season,it was concentrated mainly in the central region.From after-noon to evening,the central-northern towns and subdistricts were high-frequency areas during the early flood season,while the central-eastern towns and subdistricts predominated in the late flood season.

Abstract:To understand the precipitation characteristics and diurnal variations in Zhaoqing,statistical analyses were conducted using daily precipitation data from six national stations from 1975 to 2024 and hour-ly precipitation data from 2008 to 2024.The results indicate that precipitation in Zhaoqing exhibits signifi-cant interannual fluctuations and spatial differences,with annual precipitation,heavy rainfall days,and rainfall amounts being higher in the northern regions than in the south.The seasonal variation of precipitation is pronounced,with heavy rainfall mainly concentrated during the flood season(April-September),and ex-treme precipitation events occurring 1-2 times per year on average.The diurnal variation of precipitation during the flood season shows no significant regional differences,with precipitation amount,frequency,and intensity generally exhibiting a unimodal pattern peaking in the early evening.The diurnal variations in pre-cipitation amount and frequency also display certain seasonal changes.During the flood season,precipitation events lasting 2-6 hours contribute significantly to total rainfall,while 1-hour events are the most frequent.The highest precipitation intensity occurs in events lasting 20-21 hours.Short-duration heavy rainfall events are more frequent in the afternoon,peaking at 17:00,while precipitation intensity is higher around 21:00 and between 06:00-08:00.

Abstract:To enhance the understanding of climate change in the Xisha area of the South China Sea,this study analyzes the vertical variation and spatial distribution characteristics of air temperature from the surface to the upper atmosphere in the Xisha region based on surface and upper-air temperature data from the Xisha Islands from 2018 to 2022.The causes of temperature differences between Zhaoshu Island and Yongx-ing Island are also discussed.The results show that the five-year average temperatures at the automatic weather stations on the islands of the Xisha Islands show no significant differences,all being 27.6℃.The monthly average maximum and minimum temperatures from the surface to 850 hPa are consistent with the variations observed on the islands and reefs in the Xisha area.In the mid-to-upper layers(700-300 hPa),the monthly average maximum and minimum temperatures lag by approximately one month.The temperature variation is largest at 925 hPa and smallest at 500 hPa.There are significant differences in the number of high-temperature days among the islands and reefs,with Zhaoshu Island experiencing up to 317 high-temper-ature days,while Yongxing Island has never recorded temperatures≥35℃.The wind speed on Yongxing Is-land peaks during the noon period,and the stronger winds at noon promote air circulation,leading to lower temperatures.

Abstract:To understand the precipitation distribution and moisture transport characteristics during the pre-flood season in Heyuan City,this study investigates the precipitation distribution and moisture transport characteristics during the pre-flood season(April-June)in Heyuan City.Using ERA5 reanalysis data,rain-fall observations from 232 meteorological stations in Heyuan,and the HYSPLIT model driven by GDAS data,we analyze the water vapor transport over South China and the rainfall distribution in Heyuan during the 2024 pre-flood season.Monthly water vapor transport trajectories were simulated for the study area.The results in-dicate that precipitation in Heyuan during the 2024 pre-flood season exhibited extreme characteristics.Monthly rainfall was highest in April,followed by June and then May.Cumulative rainfall during the pre-flood season displayed a spatial pattern with the main rain area located in Dongyuan County in the central re-gion,decreasing toward the northern and southern parts.The primary rain area also showed phased spatial variations across different months.Water vapor transported to Heyuan during this period originated mainly from the western Pacific via the South China Sea and the East China Sea,with the South China Sea pathway accounting for the highest proportion(92.03％).Two airflows-one from the Bay of Bengal and the other from the western Pacific-converged over Guangdong.Before the monsoon onset(April),the water vapor flux was significantly stronger than during the transition period and after the monsoon onset(May-June).Varia-tions in the direction and intensity of monthly water vapor transport played a regulatory role in the cumulative rainfall and the positioning of the main rain area in Heyuan.

Abstract:Based on wind observation data(daily and hourly)from the Hong Kong-Zhuhai-Macao Bridge(HZMB)between 2020 and 2024,this study compares and analyzes the characteristics of wind evo-lution on the bridge with those of coastal and offshore areas in Zhuhai in terms of climatological characteris-tics,cold air,and typhoon impacts.The research evaluates wind-related risks for the road cycling event of the 15th National Games scheduled for November.Key findings include:(1)Wind speeds vary across dif-ferent segments of the HZMB,with the G3974 and G3975 segments experiencing the highest wind speeds.Along the bridge,Force 6 average winds and Force 7 gusts or higher account for 22.8％and 18.3％of oc-currences,respectively.(2)Most bridge segments exhibit a bimodal diurnal wind pattern,peaking at 08:00 LST(morning)and 19:00 LST(evening).Under cold air influence,the amplification of average wind speeds on the bridge compared to coastal Zhuhai is more pronounced than that of gusts,providing a basis for refined and differentiated operational forecasting services.(3)During typhoons,wind differences among most bridge segments are minimal,though bridge winds exceed coastal Zhuhai levels but remain lower than offshore areas.In November,the dominant wind directions on the bridge are northeasterly and northerly,with significantly higher wind speeds in these directions,indicating notable crosswind effects.Thus,event planning for November should prioritize mitigating risks from cold air-induced crosswinds on the bridge.

Abstract:To further investigate the formation mechanisms of heavy rainfall processes,this study analy-zes the characteristics and primary influencing systems of a sustained four-day extreme rainstorm event in Guangdong from August 2 to 6,2025,using hourly surface precipitation data,MICAPS data,hourly wind profile radar observations,and ECMWF numerical forecast analysis fields.The results indicate that the rain-fall coverage was extensive,with intense precipitation primarily concentrated in northwestern Guangdong,the Pearl River Delta,and coastal areas of eastern Guangdong.The maximum cumulative rainfall during the e-vent reached 918 mm,with a peak 24-hour rainfall of 609 mm.The persistence of strong high-altitude diver-gence,continuous transport of energy and moisture by low-level warm advection,and the prolonged stability of a mid-level vortex shear line over central Guangdong were key factors contributing to the extreme rainfall in inland regions.Additionally,the intensification and northward shift of the southwest monsoon,coupled with strong convergence ahead of the boundary layer jet,led to heavy rainfall in coastal areas of Guangdong.

Abstract:To ensure the successful hosting of the 15th National Games and Para Games(Shenzhen Di-vision),a statistical analysis of climatic characteristics during the event periods(November 9-21 and De-cember 8-15,2025)was conducted using data from the Shenzhen National Basic Weather Station(1953-2024)and automatic weather stations across the city(2006-2024).The results indicate that high-impact weather events during the games include rainfall(17.7％-21.9％),strong winds(12.7％-13.3％),cold conditions(1.8％-16.8％),typhoons(0％-4.2％),and heavy rain(0.3％-0.5％).Rainfall has the highest probability of occurrence,with a risk of extreme precipitation,necessitating focused attention on its impact on competition venues and transportation.Wind speeds are generally light,but strong winds may occur in coastal areas of the east and west,posing potential threats to outdoor events.Temperatures are generally suitable,but precautions are needed against cold and dry conditions affecting athletes and specta-tors.The probabilities of typhoons and thunderstorms are low,yet corresponding emergency plans should still be developed.

Abstract:To provide a reference for refined meteorological forecasting in Guangdong Province,this study utilizes observational data from 2324 automatic weather stations in Guangdong Province from 2014 to 2023,where the hourly maximum instantaneous wind speed was≥17.2 m·s-1(Force 8).The Inverse Distance Weighting interpolation method was employed to analyze the refined spatiotemporal distribution characteristics.The results indicate that the frequency of Force 8 and above thunderstorm high winds in all regions generally exhibits a diurnal variation characterized by an increase in the afternoon and a decrease af-ter sunset,although actual distributions vary across different regions.The Pearl River Delta and northern Guangdong regions experience the highest frequency of Force 8 and above thunderstorm high winds in May,while eastern Guangdong,northeastern Guangdong,and western Guangdong regions peak in July.Areas with a higher frequency of Force 8-9 thunderstorm high winds include the southeastern coastal areas of eastern Guangdong,central parts of western Guangdong and the Leizhou Peninsula,as well as areas west of the Pearl River Estuary in the Pearl River Delta region.Regions with a relatively high frequency of Force 10-11 thunderstorm high winds are mainly located near Yinna Mountain in Meixian County,northeastern Guang-dong,and near Datian Peak in Dacheng Town,Xinyi City,western Guangdong.Areas with a higher fre-quency of Force 12 and above thunderstorm high winds primarily include the vicinity of Yinna Mountain in Meixian County,northeastern Guangdong;the southwestern side of Honghai Bay and Haimen Bay in the southern part of eastern Guangdong;Ruhu Town,Huicheng District,Huizhou City,in the Pearl River Delta region;Pinggang Town,Jiangcheng District,Yangjiang City,in western Guangdong;and the central part of the Leizhou Peninsula.

Abstract:To enhance the refined service level of high-temperature weather forecasting and warning in Maoming,this study utilizes hourly maximum temperature data from five national meteorological observation stations in Maoming from 2009 to 2024 to investigate the spatiotemporal and periodic variation characteristics of high temperatures.The results indicate the following.(1)The spatial distribution of high-temperature days and duration shows a pattern of higher values in the central area and lower values in the southern area,with the maximum value exceeding the minimum by more than four times.The average duration of a single high-temperature event ranges from 2.8 to 3.1 hours,with little variation among stations.(2)High temper-atures are concentrated from mid-May to early October,with the peak period occurring in late July.The tem-perature range of 35-36℃is the primary high-temperature interval,with the highest probability of occur-rence in October for 35-36℃,in July for 36-37℃,and in May for temperatures above 37 ℃.High temperatures mainly occur between 12:00 and 19:00,with the peak occurring between 15:00 and 16:00.(3)The duration of high temperatures exhibits time scales of 5 years,11 years,and 16 years,with corre-sponding variation cycles of 4 years,7 years,and 13 years.

Abstract:To provide references for climate prediction,disaster prevention and mitigation,and agricul-tural production,this study analyzes the spatiotemporal variation characteristics of the annual extreme maxi-mum temperature,number of high-temperature days,and frequency of high-temperature processes in Qingyuan City.The analysis is based on daily maximum temperature data from seven national meteorological observation stations in Qingyuan City from 1962 to 2023,utilizing comprehensive methods including linear trend estimation,polynomial fitting,the Mann-Kendall non-parametric statistical test,and Inverse Distance Weighting interpolation.The results indicate that over the past 62 years,the annual extreme maximum tem-perature,number of high-temperature days,and frequency of high-temperature processes in Qingyuan City have all shown significant increasing trends.Concurrently,the onset of high-temperature weather has ad-vanced,and its end has delayed,further revealing a trend towards an increasing temporal span of high tem-peratures throughout the year in Qingyuan City.July is the month most severely affected by high tempera-tures,with both the monthly average number of high-temperature days and the monthly extreme daily maxi-mum temperature ranking the highest in the year.Over the past 62 years,the spatial distribution of annual extreme high temperatures,number of high-temperature days,and frequency of high-temperature processes in Qingyuan City generally exhibited a pattern of higher values in the north and lower values in the northwest and south.The extreme maximum temperature occurred in Lianzhou,while Yangshan recorded the highest number of high-temperature days and frequency of high-temperature processes.

Abstract:To evaluate the applicability of ERA5 reanalysis data in typhoon weather systems,high-al-titude observational data from dropsonde observations conducted by the Hong Kong Observatory and the Gov-ernment Flying Service during Typhoons"Prapiroon"and"Yagi"were used to systematically assess the ca-pability of ERA5 in characterizing the vertical structures of temperature,relative humidity,and wind fields within different wind circle regions of the typhoons(outside the 7-level wind circle,inside the 7-level but outside the 10-level wind circle,and inside the 10-level wind circle).The results indicate the following.(1)Under all experimental groups,the vertical temperature structure distributions of ERA5 and dropsonde data were nearly identical,increasing with decreasing height;the root mean square error of temperature was controlled within 1℃.(2)ERA5 exhibited weak capability in characterizing both the vertical structure and magnitude of relative humidity,with correlation coefficients between the two showing weak positive or even negative correlations across all experimental groups.(3)ERA5's representation of wind direction in the troposphere was largely consistent with the dropsonde data,and it demonstrated a certain capability in char-acterizing the vertical distribution of wind speed.The correlation coefficients between the two ranged from 0.4 to 0.9 across all experiments,with root mean square errors for wind speeds below30 m·s-1 controlled at around 2 m·s-1.However,for wind speeds exceeding 40 m·s-1,ERA5 tended to exhibit a bias toward lower wind speeds.

Abstract:To understand the climatic characteristics of extreme precipitation in Qingyuan City,daily precipitation data from seven national meteorological stations in Qingyuan from 1962 to 2023 were analyzed.Methods such as the percentile threshold method,linear trend estimation,Mann-Kendall test,and Morlet wavelet analysis were employed to examine the trends,abrupt changes,and periodic variations in extreme precipitation amount,days,intensity,and contribution rate.The results indicate the following.(1)The thresholds for extreme precipitation,as well as the maximum values of extreme precipitation amount,days,and intensity,all occurred in Fogang,showing a spatial distribution that decreases from the southeast to the northwest.(2)The annual average extreme precipitation amount,days,and intensity in Qingyuan City gen-erally exhibited an upward trend,with monthly distributions being largely consistent.A significant decrea-sing trend was observed in extreme precipitation amount and days from 1981 to 1990,while a significant in-creasing trend,most pronounced in 2021-2023,was noted in extreme precipitation amount and intensity.(3)The average contribution rate of extreme precipitation was 29.9%,with a climate tendency rate of 0.0077(10a)-1,indicating an increasing trend in the contribution rate of extreme precipitation.No abrupt changes were detected in extreme precipitation amount,days,or intensity.(4)Both extreme precipitation amount and days exhibited interannual periodic variations of 5-8 years,with similar timing.Additionally,quasi-15-year oscillations were observed in extreme precipitation amount,days,and intensity,persisting throughout the entire time series.

Abstract:To enhance the waterlogging disaster prevention capacity and improve the urban drainage warning system in Jinwan District,Zhuhai City,this study analyzed waterlogging incidents and rainfall obser-vation data from 2023 using correlation analysis,linear regression analysis,and probability density statistics.The relationship between rainfall and waterlogging was investigated by examining waterlogging data and rain-fall amounts at different time scales.The results indicate that rainfall at different time scales affects waterlog-ging to varying degrees,with the 3-hour rainfall having the most significant impact.Thresholds for water-logging initiation at various locations were determined:waterlogging begins when the 1-hour rainfall intensi-ty reaches 20 mm,the 2-hour intensity reaches 35 mm,and the 3-hour intensity reaches 45 mm.The risk of severe waterlogging increases significantly when the 1-hour rainfall intensity reaches 35 mm,the 2-hour intensity reaches 40 mm,and the 3-hour intensity reaches 60 mm.

Abstract:Based on NCEP/NCAR reanalysis data and conventional meteorological observation data,this study employs mathematical and statistical methods to analyze the anomalous characteristics of precipita-tion and their causes during the pre-flood season(April to June)in Guangdong in 2024.The results show that the flood season in Guangdong started earlier in 2024.The total pre-flood season rainfall was 52%more than normal,reaching a record high for the same period.The number of precipitation days increased by 11.2 days,with the precipitation exhibiting pronounced intraseasonal variation.Early-stage sea surface tem-perature changes and concurrent atmospheric circulation patterns significantly influenced the abnormally high precipitation.The moderate-strength El Niño event that started in May 2023 peaked in winter and then en-tered a decay phase.Associated sea surface temperatures in the tropical Indian Ocean and the North Atlantic Ocean were historically high during winter and maintained an anomalously warm trend into spring.Affected by the El Niño event,an anomalous anticyclonic circulation developed over the Philippines.Under the com-bined effects of the Philippine anticyclone and tropical Indian Ocean warming,the Western Pacific Subtropi-cal High during the pre-flood season showed abnormally strong intensity and an anomalously westward-exten-ding ridge point.Located on the northern flank of the subtropical high,Guangdong experienced continuous moisture transport from the South China Sea and the northern Bay of Bengal.Coupled with active plateau troughs and southern branch troughs,these conditions led to frequent heavy precipitation processes during the pre-flood season in Guangdong,characterized by prolonged duration,abnormally high cumulative rain-fall,and high precipitation intensity.

Abstract:To understand the spatiotemporal distribution characteristics of extreme short-term heavy rainfall in Shaoguan,hourly precipitation data from 140 automatic weather stations in Shaoguan from 2014 to 2023 were analyzed using the percentile method.The results indicate that the distribution of maximum hourly precipitation in Shaoguan exhibits significant spatial variability,with the most concentrated range being 50-70 mm.Stations with precipitation below 50 mm are most prevalent in Lechang.The 99.8th percentile is the most suitable threshold for defining extreme short-term heavy rainfall in Shaoguan.The high-threshold ar-eas are concentrated in the central and southern regions,while the low-threshold areas are in the north-west.The average threshold for extreme short-term heavy rainfall across different regions ranges from 36.9 to 46.3 mm.The spatial distribution of precipitation intensity generally decreases from the southeast to the northwest,with stations exceeding 50 mm·h-1 mainly located in the southern and central parts of Sha-oguan.The frequency of extreme short-term heavy rainfall shows an increasing trend year by year,with an average occurrence of 0.7 events per station annually.Both the frequency and number of stations exhibit dis-tinct bimodal monthly and diurnal variations.The monthly peaks occur in June and August,while the diur-nal peaks are at 05:00 and 18:00.Extreme short-term heavy rainfall is most likely to occur around dawn and dusk,though the intensity remains consistent between daytime and nighttime rainfall.