The snow cover in winter and spring on the Qinghai-Xizang （Tibetan） Plateau has a significant inter-annual variation， which has a certain indicative significance for the prediction of summer precipitation in eastern China.Due to the special complex terrain， the distribution of meteorological stations on the Tibetan Plateau is sparse and uneven.The uncertainty of the plateau snow cover information provided by reanalysis data and satellite data is a key issue affecting and constraining the study of snow variability and its weather-climate effects.Based on the multi-source snow data from station observations， reanalysis （ERA5 and NOAA-V3）， and satellite inversion （MODIS snow cover and IMS snow cover） on the Qinghai-Xizang （Tibetan） Plateau， this paper highlights the uncertainties of the multi-source plateau snow data in characterizing the inter-annual variability of the snow cover by means of multivariate statistical methods such as bias analysis， root-mean-square error and correlation analysis.By comparing the spatio-temporal distribution and variation characteristics of various snow data， we aim to improve the knowledge of the applicability of multi-source plateau snow data and provide meaningful references for subsequent related studies.The results show that： （1） In terms of the snow data given by the reanalysis data， the ERA5 snow depth exhibits a better depiction of the observed snow depth at the plateau stations compared to the NOAA -V3 snow depth.The mean bias and root-mean-square error of the ERA5 snow depth data are relatively small， except for some stations in the central-eastern part of the plateau， while NOAA-V3 snow depth is to some extent overestimated throughout the plateau； （2） Both reanalysis （ERA5 and NOAA-V3） and satellite inversion （MODIS as well as IMS snow cover） snow data and the station-observed snow depth on the plateau show good consistency in terms of interannual variability characteristics； Where the ERA5 reanalysis is more similar to the observed snow data on the plateau station in terms of long-term trend； In addition， decadal trend in Northern Hemisphere snow cover and station-observed snow depth appear more similar； （3） The spatial discrepancies in the distribution of snow depth and snow cover on the plateau was observed in the reanalysis data （ERA5， NOAA-V3）， in which the large value areas of NOAA-V3 in the years of more and less snow are located in the southern and northern margins of the plateau and in the central-eastern part of the plateau， while the large value of ERA5 are mainly distributed in the central-eastern， western and southern margins of the plateau.However， the differences between the respective snow depth and snow cover for each reanalysis data are relatively small， and the difference distribution between the snow anomalies years is relatively consistent， with the positive anomaly areas located in the central， western and southern margins of the plateau and the negative anomaly areas in the northern part of the plateau for both snow depth and snow cover； （4） The large value areas of snow cover for all three satellites in snowy years are located in the central-eastern and southern part of the plateau as well as in the western region.The difference distribution of snow cover in the increased anomalies years is also consistent for each type of satellite data， but the negative anomalies at the northern edge of the plateau reflected in the reanalysis data are not reflected in the satellite snow cover data， which may be related to the short coverage time of the satellite inversion snow data and different processing methods.

The Qinghai-Xizang Plateau has complex terrain and climate， which is a great challenge to the airdrop parachute landing and aviation safety.This research focuses on Qinghai-Xizang Plateau wind field simulation in boundary layer based on numerical calculation method.Firstly， the study built a WRF-LES system and scaled down to 40 m horizontal resolution based on the large eddy simulation （LES） scheme of WRF （Weather Research and Forecasting） model， and undertook the application study of large eddy simulation on the Qinghai-Xizang Plateau.Based on a strong wind case over the Qinghai-Xizang Plateau， the impacts of LES scheme and terrain elevation data on wind field simulation were evaluated through sensitivity tests.Then， the parameters in the standard sub-grid turbulent stress models of LES scheme were analyzed， and the optimal schemes for wind field simulation on the Qinghai-Xizang Plateau was obtained.Finally， a batch test was conducted to verify the applicability of the optimal schemes to the Qinghai-Xizang Plateau wind field simulation.The test results show that the WRF-LES system with a resolution of 40 m can simulate more precise and accurate wind field information， and the MAE （Mean Absolute Error） of simulated wind speed is reduced by 1.4 m·s^-1 and the RMSE （Root Mean Square Error） is reduced by 1.81 m·s^-1 compared with the ACM2 scheme； The high-precision ASTER terrain data can also improve the effect of wind field simulation， and the error is approximately deduced by 0.2 m·s^-1； The LES scheme that use 1.5-order turbulent flow energy scheme and set parameter coefficient 0.1 has the best simulation result， and the MAE is 1.56 m·s^-1 and RMSE is 2.06 m·s^-1； The batch test verifies that the large eddy simulation scheme is fit for the wind simulation on the Qinghai-Xizang Plateau， and the wind field simulation results in the 40 m resolution is significantly better than in the mesoscale resolution.The result shows that WRF-LES system can provide accurate wind field information for the parachute landing on the plateau.

The stratification of soil in land surface models is a crucial aspect that requires careful consideration.Typically， the surface layer of soil， which is significantly influenced by the atmosphere-ground interface， should be subdivided.Furthermore， as the soil goes deeper， the thickness of the soil layers can be increased accordingly.Previous studies have demonstrated that the thickness of soil below the root zone has varying effects on simulation results under different weather and climate integration conditions.Therefore， the soil stratification mode should be adjusted based on the research requirements.However， the optimal soil stratification mode in land surface models remains uncertain.This paper aims to explore the sensitivity of different soil vertical discretization schemes to the simulation of soil hydrothermal properties， surface radiation flux， sensible heat flux， and latent heat flux using the BCC_AVIM land surface model.The original scheme of soil stratification in the BCC_AVIM land model consists of 10 layers.In this study， the node depth， soil layer thickness， and interface depth of soil layers were interpolated from the original 10 layers to 20 layers， which is referred to as scheme 1.Additionally， the vertical soil discretization scheme in CLM5.0 was used as a reference and improved for the BCC_AVIM land model.Consequently， the original soil layer was increased from 10 to 20， which is referred as scheme 2.After comparing the results of the improved schemes 1 and 2 with those of the original scheme， it is evident that： （1） The simulation results of schemes 1 and 2 are more consistent with the measured data， and the simulation accuracy of the numerical value and changing trend of soil temperature in each layer is improved.Scheme 1 performs better in simulating shallow soil temperature.（2） The three schemes have good simulation effects on shallow soil moisture， but relatively poor simulation effects on deep soil moisture.The simulation of the variation trend and numerical value of soil moisture curve in each layer in Scheme 1 is closer to the measured data.（3） Scheme 1 is more reasonable in determining whether each layer of soil freezes or melts， which is closer to the measured data.Overall， Scheme 1 has the best simulation effect.Therefore， it can be concluded that the simulation effect of the first scheme is improved compared to the original scheme， indicating that denser and more detailed soil stratification under the same soil depth is beneficial in improving the simulation ability of the model for soil water and heat transport.Additionally， the simulation effect of scheme 1 is generally better than that of scheme 2， indicating that the shallow middle layer with more dense soil stratification under the same soil level has a positive impact on improving the simulation ability of the model on soil water-heat transport.

Using the observed precipitation data of 154 meteorological stations in East of Northwest China， NCEP/NCAR atmosphere reanalysis and Arctic sea ice data from 1961 to 2020， the possible impacts and mechanisms of the key area Arctic sea ice on the main distribution mode of precipitation in July during the main flood season in East of Northwest China was analyzed using SVD and other climatic statistic methods.The results show that there are two mainly sea ice modes influencing the distribution pattern of precipitation anomaly in July in East of Northwest China.One is that when the sea ice density in the Barents Sea and the Kuril Islands is relatively small （large）， and that in Davis Strait is relatively large （small）， wave trains propagating southeastward from the Davis Strait and southwestward from the Sea of Okhotsk are stimulated， resulting in the anomaly field of "high in the west and low in the east" （"low in the west and high in the east"） at the 500 hPa geopotential height anomaly field over the East of Northwest China， which leads to the regional precipitation anomaly exhibiting a "consistent less （more）" pattern.The other is that when the sea ice density in the eastern part of the Beaufort Sea is relatively small， the wave train from the Caspian Sea to the Okhotsk Sea is stimulated and matched with the positive geopotential height anomaly over South China， making the cold air path eastward and southward， as well as the subtropical high stronger， which together lead to the precipation characterized by "less in the north and more in the south"， on the contrary， the pattern of precipitation anomaly is reversed.The prediction model， which is established with sea ice in key areas as the prediction factors derived by “SVD projection method”， has certain prediction ability for grasping the precipitation anomaly trend and the spatial distribution pattern of the main flood season in July in East of Northwest China， especially for the "regional consistent less type" and "north more and south less type".

The short-time heavy rainfall in eastern Gansu Province is prone to disaster， and difficult to forecast and early warning.Using hourly precipitation data from encrypted meteorological stations and NCEP/NCAR reanalysis data in summer of 2010-2021， 50 regional short-time heavy precipitation events in eastern Gansu Province are Screening out.Based on the geopotential height anomaly field at 500 hPa， a combination of K-mean objective cluster analysis and subjective synoptic verification are used to classify the synoptic-scale circulation situation of these events， and construct different conceptual models of synoptic scale system configuration by analysis-by-synthesis.The results are as follows： （1） The synoptic scale circulation situation of 50 regional short-term heavy rainfall events in eastern Gansu Province can be divided into four types： plateau trough eastward moving type， southwest airflow at the edge of subtropical high type， shear between two high pressures type and northwest airflow type.（2） The southwest airflow at the edge of the subtropical high type causes the largest number of regional short-term heavy rainfall， the plateau trough eastward moving type and the shear between two high pressures type have the same frequency， and the northwest airflow type is least.（3） There are significant differences in weather system configuration， uplift conditions， water vapor conditions and unstable conditions of these four types.When the plateau trough eastward moving type， southwest airflow at the edge of subtropical high type， shear between two high pressures type occur， the position of the western Pacific subtropical high gradually advancing from west to north， and the water vapor conditions and unstable conditions are gradually improving， the baroclinic frontogenesis causes a large range of short-term heavy rainfall when the high trough leads the cold air move to southeast.The uplift condition of the plateau trough moving eastward type is the best， and the falling zone of short-time heavy rainfall is southerly.Under the situation of the shear between two high pressures type， the cold air is northward and mainly enters from the lower troposphere， and the falling zone of short-time heavy rainfall is northward too.The convergence of cold and warm air is the most intense， the baroclinic frontogenesis is the strongest， and the range and intensity of short-term heavy rainfall are also larger.The dynamic conditions and water vapor conditions of the northwest airflow type are the worst in the four types， however， the strong dry and cold advection in the middle and upper layers superimposed with the warm and wet airflow or warm temperature ridge in the lower layer formed the best unstable conditions， and short-term heavy rainfall falling zone is dispersed.

Based on the daily summer precipitation data of 99 national stations in Shaanxi Province and the ERA5 reanalysis data from 1979 to 2021， the temporal and spatial variations of extreme summer precipitation and the corresponding large-scale circulation characteristics in Shaanxi Province were studied， and the water vapor tracking analysis was conducted on the typical regions.The results showed that the extreme summer precipitation in shannxi Province exhibits more in the south and less in the north， with increasing trend in the central part of northern shannxi and the eastern part of Guanzhong.The variation trend of extreme precipitation in northern Shaanxi， Guanzhong and southern Shannxi is 0.36 mm·a^-1， 0.35 mm·a^-1 and 0.11 mm·a^-1 respectively based on REOF analysis.In summer， there are three main paths for water vapor sources that affect Shaanxi Province.The northern branch comes from the high latitude region of Eurasia， the eastern branch comes from inland river basins， and the southern branch comes from the South China Sea and the Bay of Bengal.In addition， the increase of extreme summer precipitation in Shaanxi Province after 2005 was the result of the combined effects of the high， middle， and low-level atmospheric circulation.The enhanced divergence in the high atmosphere is conducive to the upward movement， and the water vapor is more likely to enter the inland due to the westward extension of the west Pacific subtropical high in the middle atmosphere.The anomalous easterly wind in the south side of the Mongolian anticyclone and the anomalous southeast wind in the lower atmosphere are more conducive to the transport of water vapor to the northwest region.

Using FNL （Final Reanalysis Data）， ERA5 （ECMWF Reanalysis V5） reanalysis data， and GPM （Global Precipitation Measurement） global half-hourly precipitation data， a strong precipitation event in the southwestern plateau of China was selected to study the forecasting ability of two initial perturbation methods， Breeding Growth Mode （BGM） and Local Breeding Growth Mode （LBGM）， in convective-scale ensemble forecasting of complex terrain rainfall.The MODE （Method for Object-Based Diagnostic Evaluation） method based on object diagnostics was used to evaluate the model's ability to predict the location， structure， and intensity of precipitation objects， and compared with scoring methods such as Threat Score （TS） to comprehensively assess the model's forecasting performance.The results show that： （1） The ensemble forecast systems BGM-EPS and LBGM-EPS， generated using BGM and LBGM methods to produce initial perturbations， have better ensemble mean forecast scores for precipitation of all magnitude levels at 24 hours compared to the control forecast， and LBGM-EPS has a higher TS score for heavy rainfall compared to BGM-EPS， this indicates that the LBGM method has a certain improvement effect on ensemble forecasts for heavy precipitation.However， the underlying mechanisms behind the different initial perturbation methods are worthy of further investigation； （2） Overall， the WRF model can capture precipitation objects well， especially for rainfall forecasts in complex terrain of the plateau mountains， with a better overall similarity in precipitation targets for LBGM-EPS compared to BGM-EPS， highlighting the advantage of LBGM method in representing convective-scale ensemble forecasting of intense convection.The initial perturbation total energy of BGM and LBGM shows a developing trend with forecast time.In the same forecast time， LBGM has a larger perturbation total energy than BGM， which better represents the growth of forecast error.This can partially explain why the LBGM method outperforms the BGM method in terms of precipitation object matching in the MODE evaluation； （3） Compared with traditional TS scoring and other verification methods， the MODE method can better reflect the spatial position information of precipitation forecasts， and under the same convolution radius and precipitation threshold， the ensemble mean forecast based on LBGM method performs better in identifying precipitation objects.By flexibly setting the convolution radius and determining the precipitation threshold， the WRF model can capture precipitation objects in complex terrain areas during heavy precipitation events.However， the matching degree of precipitation targets in high-altitude areas is lower than that in low-lying areas.The LBGM-EPS method outperforms the BGM-EPS method in terms of the shape of precipitation objects and the matching of precipitation areas， resulting in better identification of precipitation objects.The quality of precipitation object matching using the MODE method is related to parameter settings such as precipitation threshold and convolution radius， rather than the complex terrain background related to terrain gradients.

Reliable precipitation information is particularly important for understanding the water balance and water cycle processes in the Qinghai-Xizang Plateau.As a new generation of satellite precipitation data， IMERG （Integrated Multi-satellitE Retrievals for Global Precipitation Measurement） represents an advanced iteration in satellite precipitation data， characterized by expanded coverage and heightened spatiotemporal resolution.However， due to the complex terrain in the Qinghai-Xizang Plateau， IMERG still has great uncertainty in the plateau region.In view of this， this study performs bias correction of IMERG daily precipitation data based on the Quantile Delta Mapping （QDM） method.The transfer function is established seasonally using CMFD （China Meteorological Forcing Dataset） precipitation and IMERG daily precipitation data during 2001 -2010 to correct IMERG daily precipitation during 2011 -2014.The results show that： （1） The QDM method can effectively correct the frequency， value， and spatial distribution of IMERG precipitation products， and the corrections are more effective for extreme precipitation and large negative deviation regions.The probability distribution of corrected IMERG daily precipitation is closer to that of the observations， and the precipitation deviation is more in line with the normal distribution.Monthly precipitation and the spatial distribution characteristics of annual and seasonal precipitation are improved.（2） The root mean square error of the corrected daily precipitation is reduced from 1.49 mm·d^-1 to 1.26 mm·d^-1 with an improvement by 15.44%.The critical success index CSI， probability of detection POD， false alarm rate FAR， precision rate， and F_score of the corrected daily precipitation in different precipitation intensities are improved， and the Bias score of tiny and torrential precipitation is enhanced.（3） After correction， the extreme precipitation is significantly improved， and the mean values of the simple daily intensity index （SDII） and percentile-based threshold indices （R95p and R99p） are closer to the observed values.The spatial distribution of extreme precipitation is effectively displayed， and the bias of extreme precipitation is reduced from over 30% to within 5%.The root mean square error of SDII， R95p， and R99p is reduced from 1.59， 6.54， and 14.89 mm·d^-1 to 0.65， 3.01， and 8.99 mm·d^-1 with the accuracy improved by 59.12%， 53.98%， and 39.62%， respectively.This study verifies the applicability of the Quantile Delta Mapping method in the Tibetan Plateau， which is beneficial for obtaining more accurate precipitation data for meteorological and hydrological studies in the region.

Based on multi-source observation data and ERA5 reanalysis data， the characteristics of accompanying Atmospheric Rivers （ARs） in the Guangxi warm-sector torrential rain cases during the summer of 2010-2022 （June-August） are statistically analyzed.And the typical warm-sector torrential rain process under the background of ARs in Guangxi occurred in 2 -4 June 2022 are analyzed from the perspectives of thermal and dynamic based on the diagnosis of wave activity flux， horizontal frontogenesis and adiabatic heating.The results showed that： （1） Most warm-sector torrential rain cases are accompanied by ARs.When the ARs pass through Guangxi and remain below 1000 kg·m^-1·s^-1， the increase of ARs intensity is conducive to the warm-sector torrential rain.In most cases， the ARs are in the direction of southwest to northeast， and the direction angle are between 15° and 65° when ARs pass Guangxi.（2） During the typical warm-sector torrential rain process， the East Siberian blocking and the Northeast cold vortex are extremely active， resulting in the suppression of the Western Pacific Subtropical High （WPSH） and its southerly position which keep the ARs maintain in the Bay of Bengal， South China Sea， South China and north tropical Pacific， providing sufficient water vapor for the occurrence and development of warm-sector torrential rain.The increase of the pressure gradient caused by the maintenance of the WPSH and the eastward movement of the vortex， the acceleration of the monsoon flow at night jointly strengthen the local ARs.（3） The enhancement of ARs at night promotes the local water vapor convergence and vertical transport， cause the wet layer thickened and atmospheric precipitable water increase continuously， which is conducive to the increase of precipitation efficiency.At the same time， the continuous warm and moist transport is conducive to the establishment and maintenance of unstable stratification in the lower level， and the convective unstable structure runs through the whole precipitation process.（4） The convergent uplift and lateral friction of mountain topography promote the upward movement and vertical vorticity development， which， on the one hand， is conducive to the uplift of the warm and moist air accumulated in the front of the mountain triggering convection.On the other hand， it is conducive to the maintenance of convective system and cause more water vapor to condense into rain.In addition， the continuous frontogenesis forcing caused by the accumulation of warm and moist air is also conducive to the maintenance and intensification of precipitation.（5） The strong upward movement under the influence of ARs causes a large amount of water vapor to condense continuously and release latent heat which in turn strengthens the upward movement.The convection continues to develop and strengthen under this positive feedback mechanism.

Squall lines often produce extremely disastrous gales and play a crucial role in the safety of hytropower stations.This article explores a squall line event over the lower reaches of Jinsha River on June 4， 2016， which brought 13-level wind at the canyon of Baihetan Hytropower Station.This research detect the formation mechanism of this squall line from environmental conditions and medium-scale meteorology.The following conclusions are obtained： （1） Before the squall line arrived， the ground pressure dropped steadily by 9 hPa because of the low pressure， and the temperature of the canyon rises up above 14 ℃.As the squall line arrived， the pressure rises sharply with thunderstorm high pressure， and the temperature dropped more than 10 ℃.At the same time， the relative humidity reached as higher as 70%， accompanied by short-term precipitation.After the squall line left， the aforementioned meteorological elements restored to their original values.（2） Analysis on the synoptic scale circulation， we finds that Baihetan hytropower station located in the south of southwest vortex， which induced a wind convergence background at the low level.Meanwhile， the station lied in right side of the jet stream inlet at upper level， and strong vertical motion formed by the wind shear.As a result， the squall line to come into being.Furthermore， in the troposphere before the squall line， the atmospheric circulation displayed a dry-cold advection in the middle-upper level superimposed over a warm-wet advection and higher ground temperature in the lower levels， increasing the temperature lapse rate.t As a result， the strong static instability and convection accumulated， and the conditions were favorable for the squall line to live a long time.The analyses from vertical wind speed showed that the subsidence movement made the momentum spread down， and promoted the uplift in the front side of line， and a positive feedback effect developed， promoting a stable mechanism for the strong storm.（3） Radar of Zhaotong detection indicates that echo cell that greater than 30 dBZ aggregated costly into a band and embed with the strong echo cores of greater than 50 dBZ， as a cylindrical convective cloud of higher than 10 km.On the radical velocity field， the meso-scale convergence line coinciding with the banded strong echo， as well as MARC （Mid-Altitude Radial Convergence） characteristics of the mid-altitude radial convergence， were the trigger mechanism for the squall line.As the cloud structure of the storm， strong upward movement in front of the squall line leaded to the dome.As the squall line arrived， the echo core dropped rapidly， and the extreme gale of downburst formed， resulted the new convective monomers come in being along the canyon.

On September 11， 2020， severe convective weather occurred in the southern part of Liaodong Peninsula， and wet downbursts appeared.The maximum surface wind gust at Dalian Jinzhou Desheng station reached 21.7 m·s^-1.By using conventional observation data， Dalian Doppler radar data， ERA5 data and high-resolution mesoscale simulation data， the circulation background， convective environment and echo characteristics of this wet downburst was analyzed.The results show as follow： （1）the major synoptic system is shear line made up of southwest and southeast winds located to the east of upper-level cold vortex transformed by north-moving tropical cyclone.The mechanisms of convective initiation are surface convergence line and low-level jet.Coupling upper-level divergence enhances initial connection development.The convection system moved westward and landed on the frontal zone between the ground cold pool and the east warm air， and the convergence lifting effect increased， promoting higher organization and more severe of the convection system.（2）The highly warm and moist surrounding air and the instability are favorable conditions for convection.Before convection occurred， the sounding shows dry air overlapping moist air and "V" pattern.The lifting condensation level decreases distinctly.During the wet downburst， radar radial velocity shows mid-altitude radial convergence（MARC）， low-level divergence.Before and after the gale， high and low elevations all exhibits more than 45 dBZ reflectivity notch.The high reflectivity notch at high elevation appears prior to that at low elevation.Monitoring the changes of the high elevation reflectivity contributes to the early warning of wet downburst.

Hydroelectric is one of the crucial forms of electricity generation in Chongqing， studying the intensity and distribution of summer precipitation in the Chongqing hydropower basin holds significant importance for providing reliable meteorological support for summer power generation.Currently， research efforts primarily concentrate on the Southwest region or the Sichuan Basin， with limited focus on individual hydropower basins， as a result， the potential for providing refined electricity meteorological services is restricted.In this study， by using EOF analysis， regression analysis， synthesis analysis and other methods， the summer precipitation modes and causes in hydroelectric basins of Chongqing were analyzed based on the precipitation data from 115 meteorological observation stations in Chongqing's hydroelectric basins from 1981 to 2022， as well as ERA5 reanalysis data.Furthermore， the characteristics of water vapor transport for each precipitation mode were explored.The results show that there are two main precipitation modes in the summer in the major hydroelectric basins of Chongqing： the region-wide consistent mode and the north-south reverse mode.The circulation characteristics of the consistent excessive mode in region-wide consistent mode are mainly characterized by large amplitude in the mid-high latitude geopotential height field， a stronger and southward-shifted mid-latitude westerly jet， a stronger and southward-shifted South Asian high， and a westward-shifted subtropical high， the consistent low mode are opposite.Simultaneously， there are abnormal southwest water vapor transport and convergence within the basin， which collectively result in excessive precipitation in the basin.In addition， there are four water vapor channels that influence the region-wide consistent mode， they are the southerly channel in the western Bay of Bengal， the southerly channel in the northern part of the Indochina Peninsula， the westerly channel on the eastern side of the Tibetan plateau， and the easterly channel west of the Philippines， with the eastern channel west of the Philippines having the most significant impact.The circulation characteristics of the more north and less south mode in north-south reverse mode are primarily characterized by a west-high-east-low geopotential height field in the mid-high latitudes， a northward-shifted mid-latitude westerly jet， an eastern-type South Asian high in the mid-low latitudes， and a tendency for the subtropical high to extend westward and northward.Meanwhile， there is a strong northward water vapor flux within the basin， with water vapor convergence in the northern part and water vapor divergence in the southern part， more south and less north mode are opposite.Additionally， there are two water vapor channels that influence the north-south reverse mode， they are the southerly channel in the central part of the basin and the southerly channel in the eastern part of the Philippines， exhibiting consistent changes.

Atmospheric inversion plays an important role in meteorological research and air quality research.This study used ERA5 hourly temperature profile data from 2011 to 2020 to evaluate the low-level atmospheric inversion features of six regions， including Northwest China， North China， Northeast China， Southwest China， East China， and South China.In terms of daily variation， the temperature inversion frequency and intensity mostly peak at 07:00 （Beijing time， the same as after）， the frequency and intensity of the inversion can reach 70% and 2 ℃， respectively， and the thickness of the inversion peaks mostly between 11:00 and 18:00.From the perspective of monthly variation， the temperature inversion characteristics of the sites all reach the maximum value in January to February and December， and the minimum value in June to August.The temperature inversion frequency of some sites in January can reach 90%， the temperature inversion intensity can reach more than 3 ℃， and the overall temperature inversion thickness is mostly concentrated between 200 and 400 m.When looking at annual variation， the majority of stations' temperature inversion characteristics show little change， and the annual variations in temperature inversion frequency， intensity， and thickness are about 10%， 0.4 ℃， and 60 m， respectively.While the temperature inversion features of the stations in East and South China do not clearly indicate an upward or downward trend， the stations in northeast China exhibit a general downward tendency.Ground radiative cooling， weather， and climate are the key factors that affect how temperature inversion features vary over time.Due to the effect of warm air brought by the circulation over the ocean， the coastal regions in northeast China， East China， and South China are more vulnerable to the creation of temperature inversions from the standpoint of geographical distribution.In comparison to Northwest China （23.4%）， Southwest China （13.4%）， and North China （21.84%）， the regional average temperature inversion frequency was greater in each of those three regions （44.5%， 48.7%， and 48.65%， respectively）.The temperature inversion intensity and thickness are the highest in northwest China， East China and coastal areas of South China.The temperature inversion intensity and temperature inversion thickness are above 1.5 ℃ and 300 m as a whole.The humid and cloudy environment in Southwest China is not conducive to the formation of temperature inversion layer， and the temperature inversion intensity and temperature inversion thickness are the smallest.For the subsequent analysis of the vertical buildup and diffusion of air pollutants in various locations of China， this work can serve as a scientific reference.

Based on station data and high-resolution reanalysis data， this study conducted a diagnostic analysis of the persistent heat wave that occurred in the arid region of northwest China during the summer of 2022 and quantified the contributing factors.The results showed a total of 2092 occurrences of high temperatures， primarily concentrated in the northern part of northwest China.Furthermore， the high temperatures exceeded historical extreme values recorded in the past 40 years at 108 stations and persisted for over 10 days at 98 stations， both of which are historically rare occurrences.The studied heatwave has a wide impact and long duration.During the prolonged period of high temperatures， the South Asian high-pressure center is positioned further north than usual and exhibits stronger intensity.In the early stages of the event， it is influenced by the warm ridge in the mid to upper levels， which gradually shifts eastward during the transition period.The continental high-pressure system gradually extends eastward and connects with the western Pacific subtropical high-pressure system （referred to as the "Western Pacific Subtropical High"） which extends both eastward and westward.This connection affects most of the northwestern regions.Within the northwestern region， there is strong water vapor divergence， making it difficult for precipitation to form.At the same time， there is an abnormal strengthening of the descending airflow， leading to warming in the upper atmosphere， which favors the development and maintenance of hot weather conditions.Whether it is in the early or later stages of the process， the temperature advection term contributes minimally to the warming process， while the vertical transport term and non-adiabatic heating term are key factors that influence extreme heat weather.From the perspective of influencing factors， the early stage of the process is mainly influenced by dynamic factors， while in the later stage， thermodynamic contributions dominate after the formation of a stable heat do stable heat dome.

This study utilized the 2020 -2021 China Meteorological Administration （CMA） Land Data Assimilation System （CLDAS） hourly surface air temperature （T2m） product in combination with the T2m forecast data from the CMA Shanghai Rapid Update Cycle Numerical Forecast （CMA-SH3）.A deep learning semantic segmentation model called MT-Cunet was developed to achieve a 24-hour T2m grid forecast that is updated on an hourly basis.The forecast results for 2022 were then tested and evaluated.Results showed that： MT- Cunet has demonstrated the most effective revision during the 3~9 h time horizon in the study range.It shows a significant reduction of 42.4% and 40.9% in the mean MAE and mean RMSE， respectively.The revision effect during the 10~24 h time horizon is also noteworthy， with a reduction of 26.7% and 26.3% in the mean MAE and mean RMSE， respectively.When evaluating low-temperature （≤0 ℃） and high-temperature （≥35 ℃） events， MT-Cunet exhibits a positive bias in high-temperature forecasts while showing a negative bias in low-temperature forecasts， and the magnitude of error is much smaller compared to CMA-SH3.On the spatial scale， MT-Cunet can substantially reduce the T2m forecast error in complex terrain and decrease the MAE dispersion of CMA-SH3， resulting in a more stable distribution of forecast errors.By examining and assessing the regional warming and cold wave processes in February and March 2022， it has been found that MT-Cunet demonstrates superior capability in predicting the timing and magnitude of temperature increases and decreases.In both warming and cold wave processes， the MAE of MT-Cunet is 28.9% and 33.8% lower than that of CMA-SH3， respectively.This suggests that the MT-Cunet model exhibits improved forecasting skills in transitional weather processes.Therefore， by employing a fast-updating cycle numerical model， it is possible to rapidly increase the number of forecast samples.Additionally， by refining the objective method of the semantic segmentation deep learning model， this approach effectively addresses the issue of poor performance in deep learning training caused by the limited amount of data in conventional numerical models.Furthermore， it opens up new possibilities for maximizing the utilization of domestic model resources and promoting the wider application of domestic model post-processing.

This study used multi-scale transform and positive pressure perturbation method to simplify the barotropic quasi-geostrophic vorticity equation.For a class of cosine type shear， analyzes the influence of shear westerly on Rossby solitary wave that has nonlinear Shr?dinger envelope soliton characteristics， and studied the topology of the westerly with nonlinear Shr?dinger envelope soliton wave pattern.The results show that： （1） The key to the formation of cut-off low pressure is the bifurcation of westerly shear.The shear is not only the source of the envelope Rossby solitary wave， but also leads to the change of the structural characteristics of the westerly flow field.The essence of difference between different flow patterns is the structural change that is caused by bifurcation.It indicates that there exists a critical value for shear， which changes the topology of westerly.The topology of westerly has no singular points， only a degenerate central structure， and the corresponding westerly is a zonal flow， when the shear is less than this critical value.There are singular points， and vortices are generated in the westerly， when the shear is greater than this critical value.（2） For the vortices pattern of westerly， it exhibits different flow patterns， if the location of the singular points varies.The westerly presents an Ω shaped blocking flow field， when the singularity point appears only in the northern part of the system.The westerly presents an inverted Ω shaped cut-off flow field， when the singularity point appears only in the southern part of the system.And the westerly presents a dipole blocking flow field， when singular points appear in both the north and south.（3） There are cut-off low-pressure in both the inverted Ω type field and the dipole blocking flow field.It is a Northeast Cold Vortex， if the cut-off low-pressure forms near the Ural Mountains and moves downstream to the northeast region of China.Based on the blocking situation as the source of the Northeast Cold Vortex， the formation mechanism of the Northeast Cold Vortex is discussed with both the board view （westerly shear） and local characteristics （Rossby solitary wave） considered， and thus deepens the understanding of the formation of the Northeast Cold Vortex.

Based on soil temperature and humidity and meteorological data at different elevations during the 2020-2021 growing season in the Pailugou watershed of Qilian Mountain， this study analyzed the variation characteristics of soil temperature and humidity and the relationship with meteorological factors， and determined the main meteorological factors affecting soil temperature and humidity.The results showed that： （1） soil temperature tended to increase and then decreased during the growing season （2020）， with a gradual increase in soil temperature from May to August （3.93 ℃） and a decrease from September to October （2.44 ℃）.Meanwhile， soil temperature showed a fluctuating increase with increasing elevation and a gradual decrease with increasing depth of soil layer.（2） Soil moisture showed considerable variation within the growing season， with a general trend of increase and then decrease （2020）， with the lowest soil moisture in May （0.164 m³·m^-3） and the highest soil moisture in September （0.318 m³·m^-3）.（3） The variation of soil moisture increases with elevation and decreases with the depth of the soil layer.（4） The main meteorological elements affecting soil temperature are air temperature and relative humidity， while soil moisture is mainly affected by air temperature and vapor pressure deficit.

The thermal effect has an important influence on the sand initiation process and dust vertical transport of the dust source area in Hexi Corridor， and it is a key factor to consider in the sandstorm forecast in this area.To reveal the effect of thermal effect on the intensity of cold front sandstorm in Hexi Corridor， using ECMWF ERA5 hourly reanalysis data and conventional meteorological observation data， the similarities and differences of the thermal mechanisms such as the boundary layer temperature， front function and surface heat flux on the basis of favorable background analysis of atmospheric circulation situation were diagnosed and analyzed.The results show that： （1） In addition to the influence of high and low altitude wind speed， the intensity and position of cold and warm air to ground， the intensity of center and transit time of cold front play important roles in the intensity of regional cold front sandstorm； （2） The greater the surface sensible heat flux in the afternoon and the increase of thermal flux from 09:00 （Beijing Time， the same as after） to 14:00， the stronger the intensity of the duststorm.The maximum（ 5-hour increase） afternoon sensible heat flux in general， strong and extremely strong duststorm areas are 367（307） W·m^-2， 417 （360）W·m^-2and 460（380） W·m^-2， respectively.（3） The intensity of the sandstorm increases with the temperature increase range before the outbreak of sandstorm， temperature differences between before and after the outbreak of sandstorm below 1.5 km in the boundary layer， the temperature increase range（ temperature difference）in general， strong and extremely strong duststorm areas are 2.9（-16.5） ℃， 4.9（-17.0） ℃， 7.9（-22.8 ℃）， respectively； （4） The stronger or higher of frontogenesis， the stronger the duststorm.The intensity of frontogenesis in general， strong and extremely strong duststorm areas are 208×10^-10 K·m^-1·s^-1， 477×10^-10 K·m^-1·s^-1 and 686×10^-10 K·m^-1·s^-1， respectively， the accordingly heights of frontogenes are 767 hPa， 686 hPa， 450 hPa.The results of this paper have a scientific understanding of the thermal characteristics of the sandstorm in Hexi Corridor， and provide new ideas and technical methods for improving the accuracy of sandstorm prediction and early warning.

Dust aerosols are significant components of atmospheric aerosols， and they play a crucial role in global weather and climate changes through radiative effects and the formation of cloud and precipitation.The impact of dust devils on the worldwide emissions of dust aerosols should not be underestimated.The Qaidam Desert located in the northern part of the Tibetan Plateau is a source of dust devils.To investigate the meteorology conditions that lead to the occurrence of dust devils and to understand their spatial and temporal distribution characteristics in the Qaidam Basin， the thermodynamic criteria of dust devils are examined using the ERA5 reanalysis data from 1991 to 2020.The spatio-temporal distributions of the potential dust devil and dust plumes occurrence （PDDP_hours） across the Tibetan Plateau and the estimation of dust emission caused by dust devils and dust plumes in the Qaidam Basin have been carried out based on these criteria.In the analysis of trends from 1991 to 2020， lapse rate （LR）， convective ratio （w _*/u _*）， and PDDP_hours have been examined.The precipitation from the Delingha National Basic Meteorological Station， PM_2.5 and PM₁₀ from the Delingha Air Quality Monitoring Station， and ultraviolet aerosol index （UVAI） data derived from the Aura satellite from 2016 to 2020 have been utilized to investigate the contribution of dust devils to PM_2.5 and PM₁₀ in summer in the Qaidam Basin.The results show that w_*/u_* and LR are the primary factors that influence the formation of dust devils.The PDDP_hours reveals a diurnal cycle with peaking at 12:00 -16:00 （Beijing Time） under different thermodynamic conditions.Based on the diurnal variation of the cumulative contribution of PDDP_hours， the combined w _*/u _* > 5 and LR > 10 K·m^-1 criteria are considered to be the most appropriate for determining the occurrence of dust devils in the Qaidam Basin.On the basis of the PDDP_hours criteria， the analysis highlights the significant presence of PDDP_hours in the Qaidam Basin and the southwestern part of the Tibetan Plateau in summer.The results also reveal that the larger dust devil emissions occur in summer with the average dust emission of up to 1.28×10⁵ t， which accounts for 69.8% of annual dust emissions.The lapse rate has shown a significant downward trend and the convective ratio has shown an upward trend in the Qaidam Basin， which finally lead to an obvious downward trend of PDDP_hours.The observations indicate that the annual variation of UVAI shows a larger magnitude in summer， despite there is more precipitation in Delingha during this season compared to others.It indicates that， in addition to the dust storm， dust devils may attribute to PM_2.5 and PM₁₀ in summer.

In this paper， a new numerical scheme was proposed to solve the advection equation in a multi-moment nonhydrostatic dynamical core.To guarantee the shape-preserving property， the limiting operations are devised for a hybrid discretization framework adopted by the multi-moment dynamical core， consisting of the multi-moment finite-volume and the conservative finite-difference schemes for the horizontal and vertical discretizations respectively.In the horizontal direction， a nonoscillaory scheme is accomplished by adjusting the slope of the multi-moment reconstruction polynomial at the cell center with the application of a WENO （weighted essentially non-oscillatory） algorithm.The resulting multi-moment scheme can achieve the fourth-order accuracy in the convergence test.In the vertical direction， a TVD （total variation diminishing） slope limiter is applied in the finite-difference discretization to remove the non-physical oscillations around the discontinuities.To accomplish the time marching in the proposed advection model， a second-order paired explicit Runge-Kutta scheme is adopted， which is expected to be an efficient and practical method for the advection solvers in the atmospheric models with very high spatial resolutions.The explicit time marching， without the dimension splitting， is useful to avoid the divergence errors in the advection transport calculations.Two Runge-Kutta schemes， requiring different times of conducting the spatial discretization within a time step， are combined， and used for the time marching in the different directions.The finite-difference discretization is called for six times within a time step in order to increase the maximum available CFL （Courant-Friedrichs-Lewy） number in the vertical direction， while the horizontal multi-moment spatial discretization is conducted for two times as the regular second-order schemes.As a result， the difference between the maximum time steps determined by the horizontal and vertical discretizations， due to the very large aspect ratio of the computational cells in atmospheric modeling， can be diminished.The non-negativity property of the proposed advection scheme is assured by devising a new flux-correction algorithm.It improves the existing positivity-preserving algorithm through further considering the mass flowing into the computational cell in an iterative procedure during the flux-correction operations.The proposed flux-correction algorithm can approach the necessary and sufficient condition for assuring the non-negative solutions and is more accurate for the advection calculations with CFL numbers larger than one.The widely used two-dimensional benchmark tests were checked in this study and the numerical results verified the performance the proposed advection scheme， which has the practical potential to build an accurate and efficient advection equation solver for the scalable high-resolution nonhydrostatic atmospheric models.