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Geothermal Resource as a kind of renewable energy is widely distributed in tectonically active regions. Using hot springs along the Red River fault zone as an example, this study attempts to analyze the recharge source, recharge elevation, reservoir temperature, circulation depth, mixing of cold groundwater, and heat source through ions, stable hydrogen and oxygen isotopes, and data in previous studies to determine the characteristics and formation mechanism of geothermal resources in tectonically active regions. The findings show that whereas the non-thermal groundwater is abundant in –Ca2+, the hot springs in the Red River Fault are predominantly of the –Na+ type. The stable hydrogen and oxygen isotopes indicate that the geothermal water is derived from local meteoric precipitation, with a positive excursion in the oxygen isotope indicating that the geothermal water has undergone the strong water-rock interaction under high reservoir temperature. The recharge area is located in the mountainous regions on both sides of the Red River Fault, with recharge elevations ranging from 2252 and 3482 m. The reservoir temperature varies from 67.4 to 173.42°C calculated by the SiO2 geothermometer, and the associated circulation depth is between 1601.18–5134.12 m. Furthermore, the data of previous studies suggest that the primary heat sources in the study area are mantle-derived heat, crust-derived heat, and radioactive heat, while the composition ratio of various heat sources is different from north to south because of the influence of structural development. The primary determinants of geothermal resources in tectonically active regions are the composition of the heat source and the scale and number of large faults, which in turn affect the temperature of geothermal resources. [ABSTRACT FROM AUTHOR]

This study discusses the interannual variability and influencing mechanisms of the summer precipitation dipole pattern in Northeast China from 1961 to 2020 based on observation data and reanalysis data. Results indicate that the second mode of empirical orthogonal function (EOF2) mode of summer (June–August) precipitation in Northeast China presents a dipole pattern with opposite trends in the north and south, and its time series (PC2) demonstrates significant interannual variations. The South-North dipole pattern in summer precipitation over Northeast China are significantly correlated with the tropical sea surface temperature, Arctic sea ice, and Eurasian snow cover in the preceding spring (March–May) on an interannual scale. In the preceding spring, the rise in sea temperature in the eastern equatorial Pacific and the decline in the western equatorial Pacific can stimulate EAP and EU teleconnections, positioning a cyclonic center over Northeast China, thereby influencing the dipole pattern of precipitation in Northeast China. Furthermore, the anomalies in European snow cover and Arctic sea ice can lead to an increase in albedo and a decrease in upward heat flux, causing the lower atmospheric temperature to drop and persist into the summer. This triggers the eastward propagation of atmospheric Rossby waves at mid-high latitudes, which promotes precipitation in Northeast China through the occurrence of negative potential height anomalies. These conditions influence the anomalies in the atmospheric circulation over the Eurasian continent, regulate moisture transport and vertical motion, and collectively contribute to the dipole pattern of summer precipitation in Northeast China over the past 60 years, with opposite trends in the north and south. [ABSTRACT FROM AUTHOR]

Comprehensive understanding of the complex relationship among water, energy, and carbon emissions (WEC) is crucial for achieving socio-economic structural transformation and regional sustainable development. It represents a complex systemic undertaking that necessitates coordinated efforts across multiple domains and requires intricate planning and balancing. However, as the relationships between regional water resources, energy, and carbon emissions become increasingly acute, systematically examining the circulating relationships of a typical regional Water-Energy-Carbon system under changing conditions is still a challenge for regional sustainable development. In this study, we propose an integrated framework by jointly employing the Environmental Input-Output model and Structural Path analysis to assess the embodied intensities and circulation characteristics of WEC in Shandong Province, a major energy-consuming province in China. The results indicate that in 2017, the industries with the highest embodied WEC intensities are water production and supply industry (224.36 m3/10,000 CNY), coal mining and washing industry (1.66 tce/10,000 CNY), and transportation, postal, and telecommunication industry (2.36 tons/10,000 CNY). During the study period, most industries exhibited decreasing trends in embodied WEC intensities. Notably, the energy intensity and carbon intensity showed a certain positive correlation. For Shandong Province, both the embodied WEC trade flows in 2012 and 2017 demonstrated net inflows. The changes in embodied energy consumption and carbon emissions end consumption were minor, whereas the terminal demand for water resources decreased by 10.3 billion cubic meters, with urban consumption being its main form. Agriculture serves as the largest sector for embodied water transfer and trade-in, while the construction industry is the primary sector for energy and carbon transfer and trade, with 98 % of the construction industry's embodied quantity used for fixed capital formation. This study contributes to bridge the gap in regional resource management and provides a scientific basis to make policy on water conservation, energy efficiency, and emissions reduction.

Australia has experienced increasing number of heatwave events (HWEs) in recent decades. This study aims to examine key synoptic features of austral summer HWEs over Australia during 1950/1951–2019/2020. Based on ERA5‐reanalysis and rotated empirical orthogonal functions, HWEs in Australia are categorized into four types according to where they often occur together: East Australia (EA), North Australia (NA), West Australia (WA) and Southeast Australia (SEA). Our results reveal that while anomalous anticyclones at 500 hPa level are the typical synoptic circulations responsible for HWEs of each subregion, their specific mechanisms differ between subregions. The atmospheric heat budget at 850 hPa level shows that anomalous diabatic heating promotes the onset of HWEs in each subregion. While anomalous vertical advection and adiabatic heating due to the anomalous subsidence play an important role in maintaining HWEs till their demise in NA, they only help trigger HWEs in EA, SEA and WA. Our results also suggest that anomalous advection of climatological mean temperature is important to both the onset and persistence of HWEs in EA and SEA, while it only helps sustain (trigger) HWEs in NA (WA). The advection of anomalous temperature also acts to trigger HWEs in EA, SEA and WA. On the surface, upward long‐wave radiation and sensible heat flux contribute to the development of HWEs, whereas both of them are reduced in SEA due to the enhanced anomalous cyclones near the surface and the decreased land–air temperature difference. These findings help improve understanding of the synoptic characteristics and distinctive mechanisms of HWEs in different subregions of Australia. [ABSTRACT FROM AUTHOR]

Based on the precipitation observations collected from the stations and the ERA5 analysis data, the moisture flux and budget of a rainstorm event that occurred in Jiangxia, Wuhan during the Meiyu period in 2020 were estimated. In addition, the Lagrangian hybrid single-particle orbit model (HYSPLIT4) is used to quantitatively analyze the contributions of various sources to the precipitation process during the event. The results are as follows. (1) The synoptic condition and its stability led to this rainstorm event and its maintenance. (2) The moisture was mainly transported from the South and West. It is the key for this torrential rainstorm event that the moisture was transported and concentrated through the Indian summer monsoon circulation at the lower latitude and the southerly flow surround the Western Pacific Subtropical High. In addition, the southerly inflow of moisture played an important role in the moisture budget of this rainstorm. (3) The main moisture sources of this rainstorm events were identified as the Indian Ocean, the Bay of Bengal-South China Sea, and the western Pacific, which accounted for 24%, 41%, and 34% of the total moisture supply, respectively. (4) The southern flow was the major channel for the moisture transport at 925 hPa, which mainly originated from the western Pacific and the South China Sea, while the southwestern flow was the major channel for the moisture transport at 850 hPa, which mainly originated from the Indian Ocean and the Bay of Bengal.

Recently, extreme precipitation has occurred frequently in the Tarim Basin, which has a fragile ecological environment, arousing widespread concern. Using daily precipitation observations from 42 stations in the Tarim Basin during the spring of 1980–2021 and monthly circulation reanalysis data from the European Center for Medium-Range Weather Forecasts Reanalysis v5, as well as statistical analyses and physical diagnostic methods, this study investigated the abnormal modes and the evolution characteristics and differences in atmospheric circulation. The results show that the spring precipitation anomalies in the Tarim Basin can be divided into two independent precipitation modes: the first (EOF1) is a precipitation pattern that is uniform throughout the region and the second (EOF2) is an east–west inverse pattern. Thus, there are distinct differences in the atmospheric circulation characteristics responsible for abnormal spring precipitation modes in the basin. When the precipitation across the entire basin is consistently excessive, the 500 hPa geopotential height is affected by the negative phase of the North Atlantic Oscillation related circulation, and anomalous negative geopotential height at 500 hPa and anomalous cyclone at 700 hPa control the entire Tarim Basin, favoring anomalous upward motion, and western and southwestern water vapor transport. This leaves the Tarim Basin with a net water vapor budget and abnormally high atmospheric precipitable water. The opposite situation occurs when the precipitation across the entire basin is consistently lower than normal. When there is a west-to-east precipitation gradient, the western part of the Tarim Basin is affected by the anomalous cyclone while the eastern part is affected by the amomalous anticyclone, leading to the east-west discrepancy. The western region of the Tarim Basin is dominated by upward airflow, whereas the eastern region is dominated by downward airflow, providing dynamic conditions for the west-to-east precipitation gradient. Under the influence of anomalous water vapor transport from the southwest and water vapor convergence, water vapor conditions favorable for precipitation can occur. The net water vapor in the basin also exhibited an abnormal west-to-east transport pattern. Moreover, the atmospheric precipitable water demonstrated an inverse phase distribution under the EOF2 atmospheric precipitation mode in the Tarim Basin. • The spring precipitation in the Tarim Basin significantly increased from 1980 to 2021. • Spring precipitation anomalies in the Tarim Basin reveal a uniform precipitation pattern and an east-west inverse pattern. • There are distinct differences in the characteristics of atmospheric circulation that are responsible for the abnormal modes. [ABSTRACT FROM AUTHOR]

Based on the daily air temperature data, daily NCEP/NCAR reanalysis dataset and monthly sea ice density index data, the climate characteristics, cold air moving paths and circulation typing characteristics of the cold waves during the ice-flood season in Inner Mongolia reach in recent 10 years were statistically analyzed, and the possible factors causing the variation of the cold wave frequency were further discussed. The results show that a)in recent 10 years, there are 98 times cold wave processes in Inner Mongolia during the ice-flood season. The processes last about 1 to 5 days with an average of 2.1 days, and the most common processes are that last 1 to 2 days accounting for 73% of the total. b)The cold wave frequency in Inner Mongolia reach during the ice-flood season show a significant increase rate of 1.4/a and the average frequency during 2015-2019 is 127% more than that during 2010-2014. c)According to the moving paths of cold air, the cold wave processes are classified into 4 types of north road cold air, west road cold air, east road cold air and north-east road cold air. The type with the north road cold air is the most common accounting for more than 70% of the total, while the other three types respectively accounted for less than 10%. d)The intensification of the Siberian high is the key atmospheric circulation factor that causes the increase of cold wave frequency in recent 5 years, while the decrease of arctic sea ice density is the important external forcing factor. [ABSTRACT FROM AUTHOR]

Based on the observational hourly precipitation data and the European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis 5 (ERA5) products from 2006 to 2020, 22 rainstorm processes in the eastern foot of Helan Mountain are objectively classified by using the hierarchical clustering method, and the circulation characteristics of different patterns are comparatively analyzed in this study. The results show that the occurrences of rainstorm processes in the eastern foot of Helan Mountain are most closely related to three circulation patterns. Patterns I and III mainly occur in July and August, with similar zonal circulations in synoptic backgrounds. Specifically, the South Asia high and the western Pacific subtropical high are stronger and more northward than those in normal years. The frontal systems in westerlies are inactive, while the water vapor from the ocean surface in the south is mainly transported to the rainstorm area by the southerly jet stream at 700 hPa. The dynamic lifting anomalies are relatively weak, the instability of atmospheric stratification is anomalously strong, and thus the localized severe convective rainstorm is more significant. Comparatively, rainstorm processes of pattern I are accompanied by stronger and deeper ascending motions, and the warm-sector rainstorm is more extreme. Pattern III shows a stronger and deeper convective instability, accompanied by larger low-level moisture. Rainstorm processes of pattern II mainly occur in early summer and early autumn, presenting a meridional circulation pattern of high in the east and low in the west in terms of geopotential height. Moreover, the two low-level jets transporting the water vapor northward from the ocean on the east of China encounter with the frontal systems in westerlies, which makes the ascending motion in pattern II anomalously strong and deep. The relatively weak instability of atmospheric stratification causes weak convection and long-lasting precipitation formed by the confluence of cold air and warm air. This study may help improve rainstorm forecasting in arid regions. [ABSTRACT FROM AUTHOR]

Based on the tropical cyclone best track data from Shanghai Typhoon Institute of China Meteorological Administration and the geostationary infrared satellite cloud image from April to November during 1979-2019, 189 typhoons formed in the South China Sea are selected as target cases. The circulation characteristics, dynamic and thermal conditions from 48 hours before typhoon formation to the time of typhoon generation are analyzed using the reanalysis data of the European Centre for Medium-Range Weather Forecasts (ECMWF) with 1°×1° grid. The results indicate that the typhoon in the South China Sea is formed in a large range of tropical ocean with high surface temperature, high water vapor content and unstable stratification. The development of deep convection and its distance to the tropical disturbance center can be used as an observation criterion for whether the tropical disturbance can develop into typhoon in the next 48 hours. Intertropical convergence is the dominant background circulation of typhoon formation in the South China Sea, and south-west monsoon or easterly wave are also main large-scale circulation. The center of typhoon disturbance is often in the transition zone of the vertical shear, where the vertical shear of the north side of the disturbance becomes smaller and the vertical shear of the south side becomes larger. Sometimes the disturbance center is slightly inclined to the weak vertical shear center. As a whole, there is no significant correlation between wind vertical shear and typhoon disturbance development. The center of tropical disturbance generally coincides with the center of vertical vorticity, and the center of vertical vorticity could be considered as a physical quantity representing the strength of disturbance itself. Furthermore, it is difficult to define the development of the vertical vorticity as an indicator to characterize the development trend of disturbance, while the Okubo-Weiss (OW) index is a good indicator for the development of disturbance and the determination of the disturbance location. In the process of typhoon disturbance development, there is a potential vortex column running through the whole troposphere near the disturbance center. Within the potential vortex column near the disturbance center, the interaction between lower disturbance and the potential vortex in middle and low layer is beneficial to the development of typhoon disturbance.

This study analyzed the spatiotemporal variation characteristics of extreme maximum temperature events (EMTEs) in East China in the last 60 years and investigated the relationship between EMTEs and atmospheric circulation. The arithmetic mean, linear trend, and the Mann–Kendall test were applied to daily maximum temperature (DMT) data (1961–2020) from 345 meteorological observation stations with complete observation records in East China to compile four characteristic indexes of EMTEs: intensity, consecutive days, first days, and last days. The analysis of these indexes revealed the following: (1) The annual number of days with a DMT ≥ 35 °C increased at the rate of 1.45 d/decade (p ≤ 0.05); the mutation occurred in 2009 with a growth rate before and after the mutation of 0.4 and 2.8 d/10a, respectively. Most of the region showed an increasing trend, with the most significant increase to the east of the Yangtze River Delta, in coastal areas of Zhejiang and Fujian, and south of Jiangxi. (2) The EMTE intensity rose at the rate of 0.15 °C/decade (p ≤ 0.05). Most areas showed a significant upward trend, and the historical extreme values of EMTEs mostly appeared in the 21st century. (3) The annual mean growth rate of consecutive EMTE days was 0.24 d/10a, which increased significantly after 2003. In comparison with 1961–2002, consecutive EMTE days increased by 35% during 2003–2020. The rate of increase was significant (p ≤ 0.05) for most areas east of the Yangtze River Delta, coastal areas of Zhejiang and Fujian, and areas south of Jiangxi. The mean mutation time was 2003, and the growth rate before and after the mutation was 0.4 and 1.4 d/10a, respectively. (4) The mean first EMTE day advanced and the mean last EMTE day became delayed, especially in the 21st century. Over the study period, the mean first EMTE day advanced by 12 days and the mean last EMTE day became delayed by 7 days. (5) The analysis of National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis data indicated that an increasing number of EMTEs have occurred in East China. The reason is that this region experiences atmospheric subsidence resulting from the intensification and westward extension of the subtropical high coupled with the weakening and northward displacement of the mid-latitude westerly trough. [ABSTRACT FROM AUTHOR]

In order to accurately recognize the weather process of strong sandstorms and improve the accuracy of the weather forecast of strong sandstorms, in this paper, we have carried out a systematic diagnostic analysis on the circulation characteristics and physical quantities of strong sandstorms under the background of regional environments. We selected Minqin County, Wuwei, Gansu Province, China, where strong sandstorms are frequent, as the study area, and classified the sandstorms from 2003 to 2012 into two categories: strong and weak according to the sandstorm intensity classification standard under the regional environmental background. On this basis, we implemented an analysis of the circulation characteristics of sandstorms. The results show that the strong and weak sandstorms in the study area have obvious winter circulation differences, and the formation of strong sandstorms is closely related to the winter monsoon. Meanwhile, we conducted a physical diagnosis of the strong dust storm that occurred in the area at 9 o'clock and 21 o'clock on May 27, 2006. The results show that the region where the strong dust storm occurs is relatively positive vorticity and strong convergence below 800 hPa, and negative vorticity and strong auxiliary dispersion above 500 hPa. When a strong sandstorm occurs, the vertical distribution of the helicity above it is negative in the upper part and positive in the lower part. As the center of the negative interval of high-level helicity increases, the interval of strong sandstorms also increases. At this time, the low-level cold advection strengthened. At this time, the lowlevel cold advection strengthened. [ABSTRACT FROM AUTHOR]

This study explored the spatio-temporal patterns of meteorological drought change and the mechanisms of drought occurrence in Yulin City of the northern Shaanxi by using Standardized Precipitation Index (SPI), Empirical Orthogonal Function (EOF) analysis and composite analysis based on the meteorological observation data and NCEP/NCAR reanalysis data from 1961 to 2015. The main findings of the research are as follows: (1) In the annual and seasonal drought series, there is a non-significant trend toward drought in summer, while there are non-significant trends toward wetness for the other series. Overall, the frequency of drought is low in the southeast and high in the west and the north of the study area. (2) EOF1 is characterized by a uniform pattern in the whole region, i.e., there is a feature of consistent drought or flood in Yulin City. EOF2, EOF3 and EOF4 mainly indicate opposite characteristics of the changes of floods and droughts in the eastern/western parts and the southeast/other parts in the study area. (3) In the summer of the typical drought (flood) years, the study area is controlled by the northwest airflow behind the trough (zonal airflow at the bottom of low-pressure trough), and the meridional circulation (zonal circulation) is distributed in the mid-latitudes, which is conducive to the intrusion of cold air into the south (north) of China. The cold and warm air intersection area is to the south (to the north). The water vapor flux is weak (strong) and the water vapor divergence (convergence) prohibits (enhances) the precipitation process in the study area.

Based on the daily precipitation and temperature data of 97 stations in Southwest China (SW China) form 1960 to 2009, a dry-wet index is calculated. The spatiotemporal variation characteristics of dry-wet conditions, precipitation and temperature are studied. Then the abnormal atmospheric circulation characteristics are discussed using reanalysis data. The results show that SW China has exhibited an overall trend of autumnal drought since the late 1980s, and this drought trend became more significant early in the 2000s, especially in the eastern SW China. Autumnal dry-wet variation in southwestern China showed two major modes: consistent change across the entire region and opposing changes in the eastern and western regions. The spatial distribution of dry-wet anomalies was more significantly affected by precipitation, while temporal variation in dry-wet conditions was more strongly influenced by temperature. The former mode is affected by the anomalies of the precedent SST near the Western Pacific Warm Pool, the Western Pacific Subtropical High, the East Asian Trough and the South Trough. The latter mode is related to the wind anomalies in the eastern SW China and the vertical movement in the western and eastern SW China. These are the main influencing factors for the autumn dry-wet variation in SW China, which are of great significance to the prediction of drought. [ABSTRACT FROM AUTHOR]

Liquid action and cone structure can significantly change fluidization characteristics via cooperation or competition in liquid-containing gas-solid spouted fluidized bed reactors (LGSFBR), which deserves in-depth study. The CFD-DEM method coupling with liquid bridge force model was adopted to investigate the fluidization, circulation and mixing characteristics, and thus a correlation analysis among the above multiple aspects was proposed to systematically explore interaction mechanism between the liquid action and the cone structure. The multiple analysis results show that the increase of inclination angle will cause a clear transition in the dominated interaction mechanism, i.e., the fluidization characteristics are firstly dominated by liquid action with lower inclination angle, then co-dominated by liquid action and cone structure, finally by cone structure with higher inclination angle. In conclusion, the overall fluidization state and characteristics can be associated with the cooperation and competition relationship between the liquid bridge force and the shear mixing action. [Display omitted] • LGSFBR was simulated by CFD-DEM method coupling with liquid bridge force model. • Explore the interaction mechanism between the liquid action and the cone structure. • Increase in inclination angle causes a clear transition in the dominated interaction mechanism. • In-depth mechanism analysis from the perspective of fluidization, circulation and mixing. [ABSTRACT FROM AUTHOR]

Using 32-yr National Centers for Environment Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis data, we investigated zonal propagation and circulation characteristics of the low-frequency circulation for the prevailing period over Eurasian mid-high latitude in boreal summer (May-August) in terms of empirical orthogonal function (EOF), linear regression, and phase analysis and so on. We found that the dominant periods of the low-frequency circulation are 10-30 days and it clearly shows meridional (southward) and zonal (westward) propagation features at the middle troposphere (500 hPa). The average zonal speed of the 10-30 days low-frequency oscillation (LFO) is about 9-10 longitudes per day. Further analysis shows that the southernmost part of the polar vortex in the northern hemisphere exhibits westward clockwise rotation in the eastern hemisphere in boreal summer. Also, the southernmost tips of 5400 and 5500 gpm contours, which indicate the site of the major trough in the eastern hemisphere, obviously move westwards. The southernmost tip of 5500 gpm contour line propagates westwards at the speed of about 9-10 longitudes per day, which is consistent with the mean zonal speed of the westward propagation of the low-frequency circulation. Moreover, the 10-30-day LFO-related cold air also shows west propagation feature with respect to LFO phases. The westward propagation of the LFO is the low-frequency-scale embodiment of the clockwise rotation of polar vortex. The cold air activities closely related to polar vortex or to ridge-trough system activities is the essential circulation of 10-30 days LFO circulation over the Eurasian mid-high latitude in boreal summer. [ABSTRACT FROM AUTHOR]

Based on 1961-2005 observed winter precipitation data in Northeast China, the temporal and spatial variations of snow concentration degree (SCD) and snow concentration period (SCP), together with the circulation characteristics when there is a higher SCD, are computed and analyzed. Results show that SCD in Northeast China presents a yearly rising tendency and SCP decreases obviously. In terms of decadal variation, there is a 12-year periodic variation in PCP, and since the mid-1970s there has been an 8-year short periodic variation. As to spatial variation, SCD in winter of Northeast China has increased gradually from the eastern part to the western, and the minimum value of SCD occurs in the east of Jilin Province, while the high value center is observed in the central part of the province. For the whole Northeast China, the variation tendencies are consistent in the eastern and central parts, where SCD presents a rising tendency and SCP shows a decreasing tendency. SCD in the southwestern and northern parts has a slight rising tendency, with SCD in the southwestern part having the slightest increasing tendency, and SCP in the northern part showing the slightest decreasing tendency. When a high SCD value is observed, the whole region is controlled by the East Asian deep trough at 500 hPa, and the trough becomes deeper in the western part, while a high pressure, which is easily formed and intensified in the eastern part, makes the East Asian deep trough move eastward slowly. Upper-level jet stream and low-level jet stream co-exist, and the former is stronger and takes more of a southwestward position than the latter. The high value zone of water vapor transport over the Pacific is intensified obviously, and the extent also increases. Northeast China is influenced by the water vapor transported to the northwest along the north of the high value center. [ABSTRACT FROM AUTHOR]

This study explored the spatio-temporal patterns of meteorological drought change and the mechanisms of drought occurrence in Yulin City of the northern Shaanxi by using Standardized Precipitation Index (SPI), Empirical Orthogonal Function (EOF) analysis and composite analysis based on the meteorological observation data and NCEP/NCAR reanalysis data from 1961 to 2015. The main findings of the research are as follows: (1) In the annual and seasonal drought series, there is a non-significant trend toward drought in summer, while there are non-significant trends toward wetness for the other series. Overall, the frequency of drought is low in the southeast and high in the west and the north of the study area. (2) EOF1 is characterized by a uniform pattern in the whole region, i.e., there is a feature of consistent drought or flood in Yulin City. EOF2, EOF3 and EOF4 mainly indicate opposite characteristics of the changes of floods and droughts in the eastern/western parts and the southeast/other parts in the study area. (3) In the summer of the typical drought (flood) years, the study area is controlled by the northwest airflow behind the trough (zonal airflow at the bottom of low-pressure trough), and the meridional circulation (zonal circulation) is distributed in the mid-latitudes, which is conducive to the intrusion of cold air into the south (north) of China. The cold and warm air intersection area is to the south (to the north). The water vapor flux is weak (strong) and the water vapor divergence (convergence) prohibits (enhances) the precipitation process in the study area. [ABSTRACT FROM AUTHOR]