CN110824585A - Method for measuring gale wind-rising mechanism of complex terrain area - Google Patents

Abstract

The invention relates to a method for measuring a gale wind-rising mechanism in a complex terrain area. The method integrates the dynamic and thermal processes of the earth surface of the complex underlying surface, analyzes the reasons of the generation of the strong wind of the complex terrain and the change characteristics of the factors in different seasons, utilizes the WRF (mesoscale weather forecasting) mode to quantitatively determine the background process of the large-scale atmospheric circulation, and obtains the formation and evolution mechanism of the near-formation wind through comparative analysis. According to the method, a series of complex underlying surface terrain, vegetation, soil humidity and other parameter sensitivity tests are designed, and the influences of different factors on the wind-starting process and the stress of large-scale circulation under different underlying surface conditions are obtained quantitatively, so that the reason and the influence factor of a complex terrain area gale formation mechanism and a power grid suffering gale formation are obtained. The method can provide reference data for power grid layout, wind energy resource utilization, wind disaster prediction and evaluation and the like in complex terrain areas. The disaster prevention and reduction of the wind power system and the utilization of wind energy resources can be improved, and the power transmission line wind disaster mechanism and the disaster early warning are broken through.

Description

Method for measuring gale wind-rising mechanism of complex terrain area

Technical Field

The invention relates to the field of disaster prevention and reduction, in particular to a method for measuring a gale wind-blowing mechanism in a complex terrain area.

Background

The wind field of the mountainous terrain is different from that of a flat landform condition, and the complex terrain of the mountainous area can obviously change the distribution of the wind speed of the flowing wind in the near stratum in the vertical direction and the turbulent flow structure, so that the characteristic wind field structure characteristics of the mountainous terrain, such as mountainous wind, canyon wind and the like, are formed. When the airflow passes through the peak, the airflow is blocked by the peak and flows around from the top and two sides of the peak, and the airflow is accelerated. When airflow enters the canyon from a flat open landscape, the airflow speed is increased due to the reduction of the area of the flow cross section, and the narrow tube effect of the canyon wind field is formed.

With the continuous increase of power transmission demands, various ultrahigh voltage and large-span transmission towers are continuously put into construction and use, the large-span transmission towers are usually constructed at positions with higher terrain in mountainous areas (such as mountaintops), and the wind field acceleration effect caused by the complex terrain and landforms in the mountainous areas causes very serious adverse effects on the wind resistance of the transmission towers. In the current domestic and foreign specifications, the regulations on the characteristics of the mountain wind field are mostly simple, the mountain wind field environment is generally considered by adopting a wind speed increasing coefficient, and a given approximate estimation formula is generally only suitable for a two-dimensional situation, namely wind speed profile data of a front windward side and a back windward side of a hillside, data under the three-dimensional situation of the whole mountain is not considered, and data of canyon wind effect specially formed for two mountains are lacked. In view of the reasons, the wind field characteristics and the causes of the wind field characteristics of the complex mountain land terrain are researched and early-warning forecast, the influence of the wind field and the quick response on the wind resistance of the transmission tower is guaranteed, the wind load characteristics under hilly and canyon terrains and the wind load effect on the transmission tower are accurately and reasonably mastered, and the method has important significance on the arrangement, safe use and operation of the transmission line in the mountainous area.

In the research of forecasting and early warning work of the current strong wind, a statistical method is often used for predicting the most probable fault probability when the same type of disaster occurs in the future according to the fault statistical data of the power transmission line when the disaster occurs in the past. In order to improve the accuracy and precision of the measuring method, a mesoscale (horizontal range is dozens to hundreds of kilometers) weather mode such as a WRF mode and a small-scale (horizontal range is hundreds of meters to dozens of kilometers) large vortex mode must be introduced, and the influence of terrain, underlying surface conditions and atmospheric condition changes is considered. Of course, to ensure that the WRF output data is relatively accurate, a large number of observations from the automated microclimate station must be available to give real-time and technical support.

Disclosure of Invention

In view of the above, the present invention aims to provide a method for measuring a strong wind-induced mechanism in a complex terrain area.

A method for measuring a strong wind-rising mechanism in a complex terrain area comprises the following steps:

a. collecting conventional hourly monitoring data for a meteorological station in a region for many years, comprising: wind speed, wind direction, temperature, precipitation, air pressure, high-precision topographic and topographic data in the area, soil, vegetation, land utilization/coverage (LUCC) data, satellite remote sensing data in the area, data of all power transmission line towers in the area and historical wind and disaster accidents of the towers;

b. removing a missing value aiming at wind direction and wind speed meteorological data of a meteorological station for many years hourly;

c, counting the distribution change characteristics of the near stratum wind field in the region to obtain the annual, monthly and daily change characteristics of the wind direction and the wind speed of the near stratum in the region, namely the season, time and region where the maximum wind speed appears, the prevailing wind direction and the daily change rule of the wind speed; exploring out the probability statistical characteristics of the seasonal variation rule, the occurrence season of the strong wind process and the occurrence date of a certain process;

d. based on long-time-series observation data and multi-source meteorological data analysis, exploring wind field distribution of a strong wind occurrence day, analyzing wind day change characteristics, a wind speed distribution rule and a wind speed distribution form, and determining the influence of surface heating and local complex terrain on near-stratum wind;

and e, carrying out a control test and a sensitivity test of the wind-induced mechanism of the near-stratum wind by using a WRF mode, and researching the wind-induced mechanism of the region from the angles of a background field and an influence factor respectively. The mode basic parameter setting comprises that a projection scheme adopts Mercator projection, terrain and the like are interpolated according to the projection, the terrain is adopted to follow mass coordinates, the mode vertical direction is from 1000hPa to 50hPa, and the total number is 40 layers. The initial integration time of the mode is 72 hours before the occurrence of the strong wind, and the simulation is finished 3 days after the occurrence of the strong wind, so that the generation, development and dissipation processes of a strong wind system are covered;

and (3) control test: selecting individual cases for development, and simulating the actually observed process of occurrence, development and dissipation of a strong wind system;

and (3) sensitivity test: sensitivity tests aiming at large-scale circulation influence, surface dynamic process influence and surface thermal process influence are respectively carried out, and sensitivity test results are compared with control tests, so that the wind generating mechanism of the complex terrain area can be obtained;

large-scale circulation background field influence sensitivity test

Multiple grid nesting is carried out to discuss the influence of large-scale circulation on the wind-starting process, triple nesting, double nesting and single nesting bidirectional nesting tests are respectively carried out, the stress effect of a large-scale circulation field on a large wind system of a research area is determined through comparison of simulation results of innermost layers of a plurality of groups of tests, and the wind-starting reason is further determined;

sensitivity test for top and two sides of mountain

The method comprises the steps of simulating and analyzing wind level changes and gale trend changes at the top and two sides of a high mountain in an area by changing wind speed and wind direction, and determining the influence of mountain trend and distribution on a wind-starting process;

sensitivity test for varying height of complex terrain

The method comprises the following steps of changing the terrain altitude of a gale occurrence area, analyzing the influence of terrain change on wind-rising time, wind-rising range, gale duration, wind direction and the like, and analyzing the influence of the terrain altitude change on gale;

susceptibility test for vegetation on underlying surface

Changing a forest into a sparse grassland, changing the forest into a grassland farmland and changing the water area by changing the vegetation type of an 8-9-level strong wind area, and analyzing the influence of the vegetation on the underlying surface on a wind-rising mechanism;

sensitivity test for influence of soil humidity on underlying surface

Quantitatively testing the influence of the soil humidity on the wind-up process by increasing/reducing the soil humidity;

f. and analyzing the dynamic and thermodynamic influence process of the regional wind mechanism according to the sensitivity test and the controllability test.

The advantages and the beneficial effects of the invention are as follows:

1. based on a strong wind simulation time period and a mode nesting grid mode selected under the background condition of annual change and the background condition of monthly change: according to the existing individual case research carried out by WRF, a long-time series background field is not considered in the experimental design, the central points of the parent/child nested regions are overlapped, the influence of the background field of the parent region on the child regions is weakened, and meanwhile, the process of a strong wind system is selected randomly. Aiming at the gale wind-rising process, the invention selects the test area and time by combining the perennial wind and the gale season of the research area established by actual observation data, and moves the sub-area along the wind direction away from the parent area, so that the influence of a large-scale background is fully reflected under the special complicated terrain condition of the research area, and meanwhile, the selection of the simulation time interval has better gale season representativeness.

2) The WRF mode comprehensively considers the influence of four factors on the wind-blowing process of the near stratum: the wind-rising mechanism of the near-stratum wind is mainly influenced by a large-scale background field, a dynamic process influenced by the terrain and a thermal process of an underlying surface, but most of the existing sensitivity test researches separately consider the influence of the factors. The invention carries out comprehensive and systematic analysis aiming at the influence factors, and is suitable for researching the wind field above the high altitude, the complex mountain area and the vegetation non-uniform underlying surface under special geographical conditions of the complex environment area to obtain the wind generating mechanism of the complex terrain area.

Drawings

FIG. 1 is a flow chart of a gale windward mechanism analysis.

FIG. 2 shows the annual variation characteristics of regional wind speed (for example, March)

FIG. 3a is a regional multi-year wind speed seasonal variation;

FIG. 3b shows the wind speed change at 2016 (March.) over 3 months.

Fig. 4 shows the regional wind speed daily variation characteristics (for example, in the case of the city).

FIG. 5 is a schematic nesting solution design (taking a geographical area as an example).

FIG. 6a is a plot of terrain greater than 2400 m sensitivity test control test elevation (using geographic area as an example).

FIG. 6b shows the terrain at the elevation of the mountain-going test in the 2400 m sensitivity test (taking a geographical area as an example).

Detailed Description

The invention takes the cloud plateau principle area as an example to explain the mechanism of the wind-rising cause of the strong wind in the complex terrain area.

The great dealing state is at the joint of the cloud high source and the transection mountain, the northwest of the terrain is high, and the southeast is low. The landform is complex and various, and the west is used as a high-mountain gorge area. The mountains are eastern and auspicious clouds are western and are taken as steep slopes. Interior mountains mainly belong to Yunling mountains and anger mountains, and the Diao-cang mountain is located in the middle of the Dalian border, such as the arch is like a screen, and Wei is tall and straight. The snow spot mountain at the junction of Jianchuan and Lijiang area orchids in North China is the highest peak of the mountains in Dali with an altitude of 4295 m. The lowest point is the red flag dam around the rage river of Yunlong county, and the altitude is 730 meters. The lakes in the state are numerous, the annual average air temperature is 15 degrees, the average maximum air temperature is 20.1 degrees, the average minimum air temperature is 8.7 degrees, the lakes belong to the monsoon climate of subtropical zone with north latitude and mountain land, and are influenced by warm and humid air flow in southwest of the Indian ocean, the constant hot air on the ground rises due to the thermal circulation of the air, the cold air around the lakes supplements, the cold air flow rate is high, the wind blows extremely violently, and the speed per hour reaches 21m/s to 28 m/s.

In order to research a gale windy mechanism of a complex terrain area, an administrative boundary line range (divided administrative boundary line ranges are given) where an analysis area is located is determined first. The method comprises the steps of mastering the geographical position (giving the geographical position) of a research area, weather conditions, basic types of underlying surfaces, soil properties, geological environment conditions and the like, wherein the large terrain in the cloud plateau of an analysis area mainly comprises the cloud plateau and a cross mountain range, and is mainly characterized in that the terrain is rugged, the terrain is complex (mountains, lakes, rivers, hills and basins), the underlying surfaces (farmlands, forests, grasslands, water bodies and cities) of different types are arranged, and the near-stratum wind of the mountainous area has close relation with the physical properties of a large system and a local underlying surface.

2. The method mainly comprises the steps of ① conventional meteorological stations for years and hour-by-hour monitoring data (wind speed, wind direction, temperature, precipitation, air pressure and the like) in an area, ② satellite observation data and precipitation and temperature inversion products based on the satellite observation data, ③ high-precision topographic and geomorphic Data (DEM) for obtaining topographic and geomorphic data with high precision produced by a surveying and mapping department, ④ land utilization/coverage data for obtaining basic parameters of surface coverage and underlying surface according to national land secondary survey data, ⑤ soil geological data for obtaining soil texture, geological and environmental conditions and the like in the area according to the fact data collected by a geological environmental department, ⑥ power transmission line and wind disaster accident data thereof for obtaining data of all power transmission lines and power tower historical wind disasters in the area according to the data provided by a power supply part.

3. The method mainly comprises the steps of ① removing missing values from wind direction and wind speed meteorological data of a meteorological station for hours and years, ② enabling horizontal resolution of obtained satellite data inversion product data to be consistent and facilitating data comparison of pixel scales, ③ enabling high-precision topographic data to be subjected to depression filling to form resolution meeting mode operation requirements, ④ enabling land utilization/coverage, soil texture and geological environment data to be subjected to rasterization processing and a coordinate system to be unified to form a pixel scale matched data set, ⑤ correcting a power transmission line and wind disasters of the power transmission line and part of paper recording materials to be digitized.

Based on the processing process, a method for measuring a gale wind-rising mechanism in a complex terrain area is provided by taking the Yuangui plateau principle area as a support. The purpose of the invention is realized by the following technical scheme, which is detailed in a flow chart 1:

1. by utilizing a basic statistical analysis method, the distribution change characteristics of the near stratum wind field in the research area are statistically analyzed, the annual, monthly and daily change characteristics of the wind direction and the wind speed of the near stratum in the area are obtained, and the seasonal change rule, the season of the strong wind process and the date of the strong wind process are found out.

1.1, counting annual variation characteristics of complex terrains (see fig. 2.), and fig. 2 shows that the annual maximum wind speed variability is 7m/s from 2009 to 2017, the maximum value of the wind speed of the Dalian state is 28m/s, the annual maximum wind speed value is 21m/s to 28m/s, the annual maximum wind speed variability is 11 months to 4 months in the next year, the annual maximum wind speed is 2 months or 3 months, and the wind speed in summer is the minimum. The maximum wind speed is mainly southwest wind, and the south wind and the west wind are second.

1.2, the generation of strong wind is considered to have seasonal regularity based on data statistics and analysis of many years, the strong wind weather of a research area mainly occurs from 11 months to 4 months in the next year, the annual maximum wind speed occurs in 2 months or 3 months, namely, the maximum wind speed occurs in the late winter and the early spring. And analyzing the condition of the circulation background field, namely moving in the south of the Tibet high pressure, simultaneously moving in the east of the high pressure of the subtropical zone, controlling the air flow above the university by the west wind flow of the south branch of the Tibet plateau, and increasing the wind speed on the university ground under the guidance of the powerful high-altitude west wind flow, namely leading the formation of the gale in the area by the large-scale circulation background field. Taking the theory as an example, the narrow tube effect caused by the special terrain of the theory makes the flow velocity of the airflow passing through the basin inlet further increase, namely the important influence of the local complex terrain conditions on the strong wind strength. Typical year of gale is further selected as an example for further detailed analysis. As can be seen from fig. 2: in 2009 to 2017, the wind speed in Dalizhou areas is gradually increased from 1 month until larger values appear in 2,3 and 4 months; wind speed gradually weakens in month 5 until wind speed reaches a minimum value in months 6 and 7, wind speed slightly rises in month 8, the wind speed slightly rises to the minimum value again in month 9, the wind speed slightly rises back in months 10 to 12, the maximum wind speed appears in the seasons of deep winter and early spring, the annual change circulation background field of wind speed in the universe region is consistent with the analysis before, the south shift of high pressure of Tibet is accompanied with the east and west recession of high pressure of subtropics, the air in the universe is controlled by strong south-branch West wind airflow in the south of Tibet plateau, and the narrow pipe effect caused by special geography in the universe further increases the flow speed when the airflow passes through the basin entrance, so as to form strong wind. By combining wind direction data, 2016 popular southward wind can be obtained, the most wind directions are southwest wind and southwest wind, and the average wind direction is southwest wind.

1.3, researching monthly change characteristics of wind direction and wind speed of the region: combining the characteristics of the annual wind speed change in the analysis area, the annual maximum wind speed in the visible area appears in 3 months (see fig. 3 a), and taking 3 months with 2016 grade 10 gale in the area as an example, the analysis of the characteristics of the annual wind speed change is carried out, see fig. 3 b. It can be seen that a strong wind system process appears in 3 rd middle of Dalizhou, and the wind speed reaches 26m/s of the maximum value of the month in 15 th of 3 months. By combining the wind direction data, the maximum wind direction of the region in 2016 can be known to be mainly southwest wind, and the southwest wind are the same, so that the wind direction of the region is consistent with the wind distribution and the main frequency of the wind counted for many years (2009-2017).

1.4, daily variation characteristics of wind speed: the big sunday change from the 2016 3 middle of month period is seen in FIG. 3: the wind speed is small at night, gradually increases in the daytime, reaches the maximum value in the afternoon, then gradually decreases, and the daily change of the wind speed is in a single-peak form. The ground wind speed is greater than that at night in the daytime, the change in the daytime is large, and the wind speed at night is stable, so that the wind speed of the stratums close to the geography is greatly influenced by ground heating, and complicated atmospheric turbulence activities existing in the geography area are caused by the influence of special terrain, so that the wind speed of the geography in the daytime is greater than that at night; the 10 th grade gale extreme occurs at 3 months, 15 days and 14 days.

2. Based on the analysis process of 1, the wind field distribution of the day of occurrence of strong wind can be obtained, and the change characteristics of the wind day are analyzed; if the wind speed is small in the analysis area at night, gradually increases in the daytime, reaches the maximum value in the afternoon, and then gradually decreases, the daily change of the wind speed is in a unimodal form. Indicating that the wind speed in this region is greatly affected by ground heating. According to the analysis, the wind speed of the big principle in the daytime is determined to be larger than that of the big principle at night, the change of the big principle in the daytime is determined to be large, and the wind speed of the big principle at night is determined to be stable, so that the reason for forming the big wind in the big principle near stratum day is determined to be as follows: the ground heating under special topography causes the complicated atmospheric turbulence activity, and the topographic wind is obvious.

3. On the basis of the analysis steps 1 and 2, a WRF mode is utilized to carry out a control test and a sensitivity test of a near-stratum wind-induced mechanism, and the regional wind-induced mechanism is researched from the angles of a background field and an influence factor respectively. The mode basic parameter setting comprises that a projection scheme adopts Mercator projection, terrain and the like are interpolated according to the projection, the terrain is adopted to follow mass coordinates, the mode vertical direction is from 1000hPa to 50hPa, and the total number is 40 layers. The initial integration time of the mode is 72 hours before the occurrence of the strong wind, and the simulation is finished 3 days after the occurrence of the strong wind, so that the occurrence, development and dissipation processes of the strong wind system are covered. The first 16 hours of the simulation results were used as the start-up time for the model, and the results after 16 hours were used for analysis. And designing a plurality of groups of sensitivity tests, and respectively testing the influence of different wind factors on the wind-blowing process. The sensitivity test carried out by the invention mainly tests parameters such as large-scale circulation background which has large influence on the wind blowing of the near-stratum, complex underlying surface topography, vegetation, soil humidity and the like (see table 1).

TABLE 1 test List

3.1 control test: first, selecting an example (taking 10-grade gale once in 2016, 3, 15 and 15 days in Dali city as an example) to carry out a control test in a simulation test: namely, a simulation test is developed under the real geographical conditions of the local area to simulate the occurrence, development and dissipation processes of the observed strong wind system.

3.2 sensitivity tests (see table 1) aiming at large-scale circulation influence, surface dynamic process influence and surface thermal process influence are respectively carried out in the sensitivity tests, and compared with the control tests, the influence of the complex conditions of the underlying surface on the wind-starting mechanism is analyzed. The sensitivity test included the following:

3.2.1 Large-scale circulating background field influence sensitivity test: the large-scale circulation background field determines whether the generation process of a large wind system in a research area is stressed by large-scale circulation by developing a multilayer grid nesting mode.

The WRF-ARW mode supports one-way and two-way, fixed and mobile nesting, the invention adopts a fixed grid, namely for a static fixed grid, nesting of multiple areas (at most 21) can be carried out, the invention mainly adopts horizontal nesting for measuring a strong wind and wind rising mechanism, the specific nesting mode can be divided into one-way nesting and two-way nesting, the integral calculation value of a fine grid does not feed back (feedback) information to a coarse grid during the one-way nesting, the two-way nesting mode can lead the grids with different precisions to simultaneously operate, a thicker grid provides a boundary value for the nested grid during the operation, and the nested grid feeds back the calculation result to the coarse grid. For example, for feedback of horizontal wind (UV) vectors, the fine grid mainly feeds back the average of 3 points in its horizontal direction to the coarse grid. The space-time step proportion of the coarse and fine grids can be freely adjusted, and tests show that the proportion matching of 1:3 or 1:5 is adopted, namely the space grid distance of the mother area is 3 times or 5 times of the space grid distance of the sub area, and the integral time step of the mother area is also equal to 3 times or 5 times of the time step of the sub area. Thus, the parent area grid performs one-step time integration, and the sub-area grids therein need to perform 3-step or 5-step time integration to reach the same time layer. Meanwhile, each time the sub-region is integrated in one step, the sub-region performs interpolation once from the corresponding parent region to obtain the boundary. The main advantage of the bidirectional nesting is that the perturbation information captured by the fine grid can be fed back to the coarse grid, so that the calculation result of the coarse grid can be improved, and the coarse grid can provide more reasonable side boundary conditions for the fine grid.

The invention adopts a bidirectional nested grid mode to respectively carry out a one-nested test, a double-nested test and a triple-nested test, determines the nested mode suitable for a research area through comparing simulation results and observation data of the innermost layer area of 3 groups of tests, and simultaneously determines whether the occurrence process of a strong wind system of the research area is stressed by large-scale circulation. The time ratio of the thick and thin grids of each nesting mode is 1:3, the grid patterns of the outermost layer areas of 3 groups of tests are 1km, 3km and 9km respectively, and the integration time steps are 3.33s, 10s and 30s respectively. Except different nesting modes, the rest parameters are set consistently (a cloud accumulation convection parameterization scheme is used in a grid area with the resolution ratio of more than 1 km), the same time is simulated, the simulation result is compared with observation data, and the simulation effect of the near-formation wind in the innermost area in the simulation result is analyzed.

① A repeated embedding test, wherein the grid distance resolution is 1km, the integration time step length is 8s, the grid center longitude and latitude is the specific gale longitude and latitude, the invention adopts the center longitude and latitude of 25.61792 degrees N and 100 degrees E, the grid point number is 313 degrees, the simulation region is as the innermost layer range of figure 5, and mainly comprises a geographical region and the periphery, and the large terrain in the environment mainly has a transverse mountain south end.

A re-nesting result indicates that there is a strong 8-grade wind in this region at case time 06UTC, which lasts 4 hours until 10 UTC. The strong wind area is located at the highest altitude of the lingering mountains, and the main wind direction of the strong wind is West wind and southwest wind.

② double nesting test, wherein grid distance distribution is 3km and 1km, outermost layer integration time step length is 24s, center longitude and latitude are 24.61792 degrees N and 99 degrees E, grid points are 232 x 232,313 x 313 respectively, the simulation area is as shown in the inner layer and the innermost layer of the graph 5, the area is all land, and the large terrain comprises transected mountains and cloud plateau.

The double nesting test result shows that 8-grade strong wind appears at 06UTC as in the single nesting test, the wind speed of the double nesting test reaches 10 grades and 11 grades at 07UTC, and the strong wind above 10 grades lasts for 3 hours. It is illustrated that the local climate conditions in the secondary inner layer can form 8-grade gale, and the formation of 10-grade gale and 11-grade gale is also influenced by the large-scale circulation field of the d01 area.

③ triple nesting tests show that the grid distances are respectively 9km, 3km and 1km, the integration time step length of the outermost layer is 72 s, the longitude and latitude of the center are 23.38444 degrees N and 96.79031 degrees E, the grid point numbers are respectively 176, 167, 232 and 313, the simulation area is shown as three boxes in figure 5, the area comprises land and sea, and the large terrain comprises transverse mountains, Yunobao plateaus and Bengal bays.

The triple nesting test results show that 10 th grade gale has developed at 06UTC, one hour earlier than the double nesting results, reaching 11 th grade at 07 UTC. Strong winds above grade 10 last for 2 hours.

①②③, it can be seen that the regional 8-level gale is formed by the local geographical conditions, the 10-11-level gale is formed by the local climate conditions and the southward moving west wind zone through the action of the transverse mountain, the Yunobu plateau and the Bengal bay area, according to the observation of the geographic region weather station, the 10-level gale is observed at 2016, 3, 15, and 14 days (Beijing), the result is consistent with the 3-layer nested grid simulation result, which indicates that the local 10-level gale is mainly southward moving west wind zone and is caused by the terrain acceleration action of the peripheral macrotopography, such as the transverse mountain, the Yunobu plateau and the Bengal bay area, so the 10-level gale has the mechanism that the 8-level gale caused by the local geographical conditions is subjected to the large scale system circulation stress to form the 10-level gale and the gale which are harmful to the transmission line.

The dual and triple nested grids have larger simulation area and can bring influence of large-scale circulation process to the local climate, in the following process of researching the influence of the complex lower cushion of the local climate on the wind-starting process, in order to remove the effect of the large system process, the single nested grid is adopted in the test, the simulation area only covers the universe and the surrounding areas, and the influence of each geographical condition of the local climate on the wind-starting stage of 8-9-level strong wind is analyzed.

3.2.2 Complex terrain Effect sensitivity test

The method comprises the steps of processing partial mountain terrains in a gale occurrence area, changing mountain elevation features by assigning values to large mountains according to low elevations, analyzing influences of terrains on gale starting time, gale distribution range, gale duration and wind direction, and comprehensively analyzing influences of complex terrains. In order to analyze the influence of the terrain where gale occurs in the geographical area, the high-altitude mountain of the section of the xanthium area in the gale occurrence area is removed, and the processing method is to assign all the high-altitude terrain data of the area larger than 2400 m to 2400 m (the altitude of the xanthium area larger than 2400 m in the main speaking area is set to 2400 m), as shown in fig. 6a, and further analyze the initial moment of 8-9 level gale occurrence at the south end of the xanthium. The result shows that the control test starts to generate 8-9 grade strong wind at the time of 06UTC, and the strong wind lasts for 3 hours; compared with the mountain-going test, as shown in fig. 6b, the wind speed level at the time of 06UTC is 4, and no strong wind greater than 4 is generated in the whole simulation stage, so that the influence of the high-altitude terrain above 2400 m in the area on the 8-9 level local strong wind is large.

3.2.3 underlayment susceptibility test

Test for changing vegetation types: the forest in the mountainous region where the 8-9-level strong wind area is located is changed into a sparse tree grassland, and the wind power level is not changed, the wind speed is slightly increased, and the range of the strong wind area is also increased. The existence of the forest can weaken the wind value, and the weakening degree does not exceed 1 grade.

3.2.4 sensitivity test for influence of soil humidity on underlying surface

Large lakes and water bodies are distributed in a research area, and the soil humidity of a water body coverage area is equal to 1; and (4) performing soil humidity increase or decrease tests on the non-water body coverage area. The test result shows that the soil humidity is increased by 40%, the maximum wind speed grade is reduced by one grade, and the occurrence time of the maximum wind speed is the same; compared with the test result of reducing the soil humidity by 40%, the test of reducing the soil humidity is earlier by 2 hours when the large-range strongest wind area of the humidity increase test is UTC 08; the increase and decrease of the soil humidity can reduce the wind value, the humidity is increased and decreased by 40%, the wind level is reduced by one level, the maximum wind occurrence time is not influenced, and the soil humidity is increased, so that the range of a strong wind area is enlarged.

4. Conclusion

In the determination of the gale wind-rising mechanism of the research area, the following results are obtained: on the basis that complicated atmospheric turbulence caused by surface heating and high and continuous terrain lifting has the greatest influence on forming local 8-9-level gale, if a large-scale system crosses the border, the complicated atmospheric turbulence is stressed by large-scale circulation, and the wind speed can reach 9-10 levels, such as the middle-latitude western wind south shift process from 11 months to 4 months next year each year. The soil humidity is increased or decreased by 40%, and the wind power level and the maximum wind occurrence time are not influenced. The range of the strong wind area can be enlarged by increasing the soil humidity. This is because the signal of soil humidity to atmospheric changes shows a certain delay effect in time, i.e. the persistence or memory of soil humidity, which can be slowly fed back to the atmosphere by "remembering" the previous climate anomaly (e.g. precipitation). The forest coverage area is changed into a sparse tree grassland, the wind power level is increased by one level, and the range of a strong wind area is also increased. The forest can weaken the wind value, and the weakening degree is 1 grade. It can be seen that the main factors in the analysis area (in the mountains of cocker mountains, li. of southern university of cloudland) forming gale of more than 10 grades are large-scale system crosses such as: southward movement of west wind caused by Tibet high pressure southeast movement and vice-high east retreat, and narrow tube effect caused by local complex terrain and atmospheric turbulence caused by ground heating.

Claims (1)

1. A method for measuring a strong wind-rising mechanism in a complex terrain area comprises the following steps:

a. collecting conventional hourly monitoring data for a meteorological station in a region for many years, comprising: wind speed, wind direction, temperature, precipitation, air pressure, regional high-precision topographic and topographic data, soil, vegetation, land utilization/coverage (LUCC) data, regional satellite remote sensing data, data of all power transmission line towers in a region and historical wind and disaster accidents of the towers;

b. removing a missing value aiming at wind direction and wind speed meteorological data of a meteorological station for many years hourly;

c, counting the distribution change characteristics of the near stratum wind field in the region to obtain the annual, monthly and daily change characteristics of the wind direction and the wind speed of the near stratum in the region, namely the season, time and region where the maximum wind speed appears, the prevailing wind direction and the daily change rule of the wind speed; exploring out the probability statistical characteristics of the seasonal variation rule, the occurrence season of the strong wind process and the occurrence date of a certain process;

d. based on long-time-series observation data and multi-source meteorological data analysis, exploring wind field distribution of a strong wind occurrence day, analyzing wind day change characteristics, a wind speed distribution rule and a wind speed distribution form, and determining the influence of surface heating and local complex terrain on near-stratum wind;

designing a sensitivity test of a near-stratum wind-induced mechanism based on WRF to obtain a regional wind-induced mechanism;

and (3) control test: selecting individual cases for development, and simulating the actually observed process of occurrence, development and dissipation of a strong wind system;

and (3) sensitivity test: sensitivity tests aiming at large-scale circulation influence, surface dynamic process influence and surface thermal process influence are respectively carried out, and sensitivity test results are compared with control tests, so that the wind generating mechanism of the complex terrain area can be obtained;

large-scale circulation background field influence sensitivity test

Multiple grid nesting is carried out to discuss the influence of large-scale circulation on the wind-starting process, triple nesting, double nesting and single nesting bidirectional nesting tests are respectively carried out, the stress effect of a large-scale circulation field on a large wind system of a research area is determined through comparison of simulation results of innermost layers of a plurality of groups of tests, and the wind-starting reason is further determined;

sensitivity test for top and two sides of mountain

The method comprises the steps of simulating and analyzing wind level changes and gale trend changes at the top and two sides of a high mountain in an area by changing wind speed and wind direction, and determining the influence of mountain trend and distribution on a wind-starting process;

sensitivity test for varying height of complex terrain

The method comprises the following steps of changing the terrain altitude of a gale occurrence area, analyzing the influence of terrain change on wind-rising time, wind-rising range, gale duration, wind direction and the like, and analyzing the influence of the terrain altitude change on gale;

susceptibility test for vegetation on underlying surface

Changing a forest into a sparse grassland, changing the forest into a grassland farmland and changing the water area by changing the vegetation type of an 8-9-level strong wind area, and analyzing the influence of the vegetation on the underlying surface on a wind-rising mechanism;

sensitivity test for influence of soil humidity on underlying surface

Quantitatively testing the influence of the soil humidity on the wind-up process by increasing/reducing the soil humidity;

f. according to the sensitivity test and the controllability test, the dynamic and thermodynamic influences of the regional wind-blowing mechanism are analyzed, and the large wind-blowing mechanism of the complex terrain area is obtained.

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