阅读说明：本技术 一种计算台风潜在生成指数的新方法 (Novel method for calculating typhoon potential generation index ) 是由 哈瑶 钟中 朱益民 于 2020-11-25 设计创作，主要内容包括：本发明涉及一种计算台风潜在生成指数的新方法,通过将台风风场从大气再分析资料中定量分离,计算对流层低层850hPa绝对涡度和对流层高低层200hPa减850hPa垂直风切变；计算600hPa相对湿度和台风潜在强度；将计算结果输入到原有的GPI指标中,进而最终获得改进后的GPI指数。本项发明所提出的新方法从物理意义和计算方案上对传统潜在生成指数GPI算法进行优化,利用不含台风风场等台风天气系统资料的要素变量来计算GPI指数,进而得到更为纯粹的大气海洋环境背景场对台风生成潜在贡献的指标。(The invention relates to a new method for calculating a typhoon potential generation index, which is characterized in that a typhoon wind field is quantitatively separated from atmospheric reanalysis data, and 850hPa absolute vorticity of a troposphere low layer and a vertical wind shear of 200hPa minus 850hPa of a troposphere high and low layer are calculated; calculating 600hPa relative humidity and typhoon potential intensity; and inputting the calculation result into the original GPI index so as to finally obtain the improved GPI index. The novel method provided by the invention optimizes the traditional potential generation index GPI algorithm on the basis of physical significance and a calculation scheme, and calculates the GPI index by using the element variables without typhoon weather system data such as a typhoon wind field and the like, thereby obtaining the index of potential contribution of a purer atmospheric marine environment background field to typhoon generation.)

1. A new method for calculating a typhoon potential generation index, the new method comprising the steps of:

the first step is as follows: obtaining the whole layer wind field structure of the atmospheric circulation background wind field from the atmospheric re-analysis data, and quantitatively separating the typhoon wind field from the atmospheric re-analysis data;

the second step is that: computing absolute vorticity eta of troposphere lower layer 850hPa by utilizing atmospheric circulation background wind field_NOTCAnd convection layer high and low layer 200hPa minus 850hPa vertical wind shear V_shear-NOTC；

Flow layer low layer 850hPa absolute vorticity eta_NOTCThe calculation formula is as follows:

whereinAndrespectively showing the latitude wind and the longitude wind of the atmospheric circulation background after eliminating the typhoon wind field on the 850hPa level;

convection layer high and low layer 200hPa minus 850hPa vertical wind shear V_shear-NOTCThe calculation formula of (2) is as follows:

or

WhereinAndrespectively representing the atmospheric circulation background latitude wind and longitude wind after eliminating the typhoon field on the 200hPa level, whereinAndrespectively showing the latitude wind and the longitude wind of the atmospheric circulation background after eliminating the typhoon wind field on the 850hPa level;

the third step: calculation of 600hPa relative humidity H and typhoon potential intensity V using conventional data_pot；

The fourth step: using the parameter η obtained in the second step_NOTCAnd V_shear-NOTCAnd the parameters H and V obtained in the third step_potCalculating GPI to finally obtain an improved GPI index;

the GPI calculation formula obtained by the new method is as follows:

2. a new method of calculating a typhoon potential generation index according to claim 1, characterized in that in the first step: the atmospheric circulation background wind field is quantitatively separated from the atmospheric re-analysis data by a typhoon wind field separation method and is applied to each standard level of the atmospheric re-analysis data.

3. A new method of calculating a typhoon potential generation index according to claim 2, characterized in that in the first step: the method for separating the typhoon wind field comprises the steps of determining the center of the position of the typhoon in the analysis data, and then performing wind field decomposition on an area which takes the point as the center of a circle and takes a certain distance as the radius.

4. A new method of calculating a typhoon potential generation index according to claim 3, characterized in that: the radius range of the wind field decomposition is set to 800km, and reanalysis data with a resolution of 1 DEG x 1 DEG or more is used.

5. A new method of calculating a typhoon potential generation index according to claim 3, characterized in that: the principle of the wind field decomposition is that the plane non-rotational motion of the incompressible fluid has a velocity potential and a flow function, the horizontal wind field in the reanalysis data can be regarded as the superposition of the non-rotational motion, the non-scattered motion and the residual error term, the velocity fields of the non-rotational motion and the non-scattered motion are superposed to obtain a typhoon velocity field by calculating the velocity potential and the flow function of the reanalysis data wind field, and the residual error term of the reanalysis velocity field and the typhoon velocity field is the atmospheric circulation background wind field.

6. The method of claim 1, wherein the method further comprises the steps of: the whole-layer wind field structure comprises a typhoon wind field component and an atmospheric circulation background wind field component, and the typhoon wind field comprises a non-rotary motion wind field and a non-dispersion motion wind field.

Technical Field

The invention relates to the technical field of typhoon climate science, in particular to a novel method for calculating a typhoon potential generation index.

Background

Typhoon (also known as Tropical Cyclone (TC)) is often used to estimate the combined impact of various environmental field elements in the atmospheric ocean on the generation of marine-generated weather scale atmospheric systems, especially characterizing the strong convective and dangerous weather system generation contributions like typhoons.

Typhoons are mainly generated and developed on tropical ocean surfaces in summer and autumn, and for typhoons affecting China, most of the typhoons move to the west, the northwest or the north after being generated in the northwest pacific and the south sea of the tropical sea, and a few of the typhoons move to the east or the south. The typhoon is likely to be generated and continuously developed and enhanced under certain atmospheric marine environmental field conditions, the classical atmospheric science theory considers that key factors influencing the generation and development of the typhoon comprise a wide warm ocean surface, small vertical shear of the wind speed of a troposphere, a rotating parameter larger than a certain numerical value and certain small disturbance to a low layer of the troposphere, and after the conditions are met, the small disturbance on the tropical ocean surface can be used as an embryo of the typhoon development and can develop and strengthen in the next few days, namely the typhoon generation. Therefore, according to the physical conditions of the atmospheric environmental field, the factors of the meteorological environment that affect the generation and development of the typhoon mainly include the sea surface temperature, the relative vorticity of the troposphere low layer, the relative humidity of the troposphere, the vertical movement of the atmosphere, the vertical wind shear, and the like.

Based on the basic theory, the concept of tropical cyclone potential generation index (GPI) is proposed by two meteorologists, Emanuel and Nolan, and the index can better describe the climatic state space-time characteristics generated by typhoon, and the GPI expression of the index is shown in the following section. This index relates to several large scale environmental factors closely related to typhoon generation, including the absolute vorticity (η) of 850hPa in the troposphere, the relative humidity (RH-relative humidity) of 600hPa in the troposphere, the cyclone potential strength (V)_pot) Wind shear (V) of 200hPa and 850hPa_shear-vertical shear). The parameter of potential strength is a diagnostic variable which depends on the difference between the temperature at which the sea gas is thermally unstable and the adiabatically rising boundary layer gas block reaches neutral buoyancy and the sea surface temperature, which relates to the sea surface temperature, sea level air pressure, vertical atmospheric temperature and the mixing ratio, and which later takes into account the effect of dissipative heating. The GPI index is applied to typhoon generation and mobile diagnosis analysis and forecast prediction, and is also applied to output data information of various weather modes for researching the weather change of tropical cyclone. A large number of results confirm that the pattern results and the observation results show a certain degree of coincidence in the seasonal variation and the generation position of typhoon, and thus prove to have a certain degree of influence on typhoon activitiesCapabilities are described.

The most similar technical scheme of the invention is the calculation mode of the above mentioned classic GPI, and the expression and calculation method of the GPI comprises the following steps:

where eta is 850hPa absolute vorticity, H is 600hPa relative humidity, V_potIs the typhoon latent strength defined by Emanuel, which is determined by Sea Surface Temperature (SST), air pressure in the vertical direction, air temperature and specific humidity and can be accurately calculated, V_shearAre the magnitudes of 200hPa and 850hPa vertical wind shear. The magnitude of the GPI calculation result respectively represents the influence of the environmental conditions of the atmospheric ocean elements on the typhoon generating activity. The large numerical value represents strong contribution, typhoon is easy to generate and develop, and frequently occurs to a scale system of the flowing weather; the small numerical value indicates weak contribution, activities such as typhoon generation and the like are restrained by environmental conditions, and strong convection weather such as typhoon and the like is not easy to develop. All data (such as wind field, humidity field, temperature field of each level of the atmosphere, sea surface temperature and the like) for calculating the GPI index can use conventional reanalysis data in the field of atmospheric science research or output data of various atmospheric modes. For example, the national center for atmospheric environmental research (NCEP/NCAR) re-analyzes data sets including high altitude 17-layer wind fields, relative humidity, vertical velocity, and temperature fields, as well as reconstructed sea surface temperature data, global sea surface temperature grid point data, provided by the National Oceanic and Atmospheric Administration (NOAA).

The traditional technical scheme is simpler and more intuitive. The data set used in the field of atmospheric science contains all parameter variables in GPI formula, and the data of all kinds of elements are directly substituted into the GPI formula, so that the result of classical GPI index space-time distribution can be calculated.

In the existing method for calculating the GPI index, the physical significance and the calculation mode of part of calculation item parameters are not accurate enough, so that the calculated GPI cannot completely and truly reflect the contribution of atmospheric marine environment field conditions generated by typhoon. The main points are as follows: the GPI index contains 2 important parameters, namely the tropospheric low-rise 850hPa absolute vorticity and the 200hPa minus 850hPa vertical wind shear (200hPa minus 850hPa latitudinal wind). Because the calculation of the contribution of each meteorological ocean element in the typhoon generation environment diagnosis is usually directed at the periods of excessive typhoon generation and active activity in summer, autumn and the like, at this time, when the absolute vorticity item of 850hPa of troposphere low-level and the shear of 850hPa vertical wind subtracted from 200hPa are calculated, the wind field of the troposphere high-level and low-level analysis data already contains a large amount of wind field information of typhoon systems, and particularly in the areas and periods of strong typhoon and ultra-strong typhoon activity, the influence of the wind field on the calculation result is more obvious, so that the GPI index calculated under the condition is actually the possibility of 'diagnosing' generation of the typhoon systems by using the change characteristic of the typhoon systems, the diagnosis result has larger deviation, and even has wrong logic contrary to the 'potential generation index' design original purpose. The index analysis is utilized to research the related problems of typhoon activities in the atmospheric science field, so that the contribution of an environmental field to typhoon generation is exaggerated in the analysis result, and meanwhile, the judgment of the potential typhoon generation possibility is deviated, so that the accuracy of the contribution diagnosis of the environmental field to typhoon generation is greatly reduced.

Disclosure of Invention

The invention aims to provide a novel method for calculating a typhoon potential generation index, which is characterized in that when a GPI index is calculated, the influence from a typhoon system is removed from the terms of 850hPa absolute vorticity of a convection layer and 200hPa minus 850hPa vertical wind shear of a high and low layer of the convection layer, and the GPI index is calculated by using element variables which do not contain typhoon weather system data such as a typhoon field and the like, so that an index of potential contribution of a purer atmospheric ocean environment background field to typhoon generation is obtained, and the problems in the background technology are solved.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a new method of calculating a typhoon potential generation index, the new method comprising the steps of:

the first step is as follows: obtaining a whole-layer wind field structure of an atmospheric circulation background wind field from atmospheric reanalysis data, wherein the whole-layer wind field structure comprises a typhoon wind field component and an atmospheric circulation background wind field component, quantitatively separating the typhoon wind field from the atmospheric reanalysis data, the typhoon wind field comprises a non-rotational motion wind field and a non-dispersive motion wind field, and removing the typhoon wind field from the whole-layer wind field structure;

the second step is that: computing absolute vorticity eta of troposphere lower layer 850hPa by utilizing atmospheric circulation background wind field_NOTCAnd convection layer high and low layer 200hPa minus 850hPa vertical wind shear V_shear-NOTC；

Flow layer low layer 850hPa absolute vorticity eta_NOTCThe calculation formula is as follows:

whereinAndrespectively showing the latitude wind and the longitude wind of the atmospheric circulation background after eliminating the typhoon wind field on the 850hPa level;

convection layer high and low layer 200hPa minus 850hPa vertical wind shear V_shear-NOTCThe calculation formula of (2) is as follows:

or

WhereinAndrespectively represents the atmospheric ring after eliminating the typhoon field on the 200hPa levelFlow background weft and warp, whereinAndrespectively showing the latitude wind and the longitude wind of the atmospheric circulation background after eliminating the typhoon wind field on the 850hPa level;

the third step: calculation of 600hPa relative humidity H and typhoon potential intensity V using conventional data_pot；

The fourth step: using the parameter η obtained in the second step_NOTCAnd V_shear-NOTCAnd the parameters H and V obtained in the third step_potCalculating GPI to finally obtain an improved GPI index;

the GPI calculation formula obtained by the new method is as follows:

in the above new process, in the first step: the atmospheric circulation background wind field is quantitatively separated from the atmospheric re-analysis data by a typhoon wind field separation method and is applied to each standard level of the atmospheric re-analysis data.

In the above new process, in the first step: the method for separating the typhoon wind field comprises the steps of determining the center of the position of the typhoon in the analysis data, and then performing wind field decomposition on an area which takes the point as the center of a circle and takes a certain distance as the radius.

In the new method, the radius range of the wind field decomposition is set to 800km, and reanalysis data with a resolution of 1 DEG x 1 DEG or more is used.

In the new method, the whole-layer wind field structure comprises a typhoon wind field component and an atmospheric circulation background wind field component, and the typhoon wind field comprises a non-rotational motion wind field and a non-scattered motion wind field.

In the new method, the principle of the wind field decomposition is that the plane of incompressible fluid has no rotational motion and has velocity potential and flow function, the horizontal wind field in the reanalysis data can be regarded as the superposition of no rotational motion, no scattered motion and residual error terms, the velocity fields without rotational motion and no scattered motion are superposed to obtain the typhoon velocity field by calculating the velocity potential and flow function of the reanalysis data wind field, and the residual error terms of the reanalysis velocity field and the typhoon velocity field are the atmospheric circulation background wind field.

Compared with the prior art, the invention has the beneficial effects that: when the GPI index is calculated, the influence from the typhoon system is removed from the terms of the convection layer 850hPa absolute vorticity and the convection layer high and low layer 200hPa minus 850hPa vertical wind shear, the GPI index is calculated by using the element variables without typhoon weather system data such as a typhoon wind field, and the index of potential contribution of the atmospheric marine environment background field to the typhoon generation is further obtained.

Specifically, the method removes the wind field data information of typhoon in the atmospheric circulation, calculates two parameters of absolute vorticity and vertical wind shear by only using the atmospheric background wind field, and substitutes the parameters into the GPI index. The improved GPI index can be considered as potential contribution of a pure environmental background field to generation and activities of a typhoon weather system due to the fact that the improved GPI index does not contain typhoon information interference, and the indication capability of the improved GPI index to the generation relation of the atmospheric marine environmental conditions, typhoons and other marine strong convection weather scale disturbance systems is greatly improved, so that the purpose of objectively and quantitatively and accurately evaluating the influence of the atmospheric marine background field on the typhoon activities is achieved.

Drawings

FIG. 1 is a flow chart of an embodiment of the present invention;

FIG. 2 is a schematic diagram of a computational process implemented by the present invention;

FIG. 3 is a schematic view of a positioning analysis typhoon center implemented in the present invention;

FIG. 4 is a graph of an 850hPa wind field and a vorticity field of the Western Pacific ocean at 27, 12 months 8, 1997 in which (a) the reanalyzed data fields, (b) the typhoon field, (c) the ambient air circulation background wind field has a contour interval of 10^-5s^-1(ii) a The average 850hPa wind field and vorticity field in 6-10 months of the northwest Pacific in 1997, (d) reanalysis of the data field, (e) typhoon field, (f) atmospheric circulation background wind field, and the interval between the contour lines is 10^-6s^-1(ii) a The solid and dashed lines represent positive and negative vorticity, respectively.

Detailed Description

The technical solution of the present invention is further described in detail with reference to the accompanying drawings and examples.

As shown in fig. 1 and 2, a new method of calculating a typhoon potential generation index includes the steps of:

the first step is as follows: and obtaining the whole layer wind field structure of the atmospheric circulation background wind field from the atmospheric re-analysis data, and quantitatively separating the typhoon wind field from the atmospheric re-analysis data.

The whole-layer wind field structure comprises a typhoon wind field component and an atmospheric circulation background wind field component, the typhoon wind field comprises a non-rotary motion wind field and a non-dispersion motion wind field, and finally the typhoon wind field is removed from the whole-layer wind field structure.

The atmosphere reanalysis data serve for numerical weather forecast or weather pattern analysis and the like, the numerical weather forecast is more common, and most of weather forecast seen by people at ordinary times is estimation and judgment of a weather numerical pattern simulation result. The core of the numerical model is a set of atmospheric dynamics equations, and in order to obtain a better result, the solution of the equations needs accurate boundary conditions and initial conditions, which are provided by input data, namely, atmospheric re-analysis data.

In order to eliminate the space-time distribution characteristics of a typhoon wind field and the variation rule of the strength of the space-time distribution characteristics, and obtain the homogeneous distribution of the atmospheric environment under different climatic backgrounds, so that the accurate contribution of factors such as the vorticity of the atmospheric circulation background wind field, the vertical wind shear and the like in the environmental field to the generation and the activity of the typhoon can be more accurately analyzed, the first step of the invention is to remove the typhoon vortex wind field from the atmospheric reanalysis data.

The principle of removing the typhoon vortex wind field is that the incompressible fluid plane can be decomposed without rotating motion, the relevant wind field information of the typhoon can be quantitatively separated from the analysis data after the decomposition, and the method is applied to each standard level of the atmosphere re-analysis data, so that the whole layer wind field structure of the atmosphere circumfluence background wind field can be obtained. The method is a conventional means in typhoon numerical simulation and forecast, and achieves the purpose of simplifying the nonlinear action between atmospheric circulation systems with different scales by decomposing the global wind field data on different atmospheric pressure surfaces into typhoon components and background components.

The specific method for removing the typhoon vortex wind field comprises the steps of firstly determining the center of the position of the typhoon in the analysis data, and then carrying out wind field decomposition on an area which takes the point as the center of a circle and takes a certain distance as the radius. The process of determining the center of the analytic typhoon is shown in fig. 3, and the grid point of the reanalysis data closest to the positioning position of the optimal path set of the typhoon in the analytic data is used as the real typhoon center, the grid point with the maximum positive vorticity on the reanalysis data is searched by taking 600km as the radius (r _ search), the searched grid point is used as the center of the analytic typhoon, and the atmosphere reanalysis data is decomposed into typhoon wind field components and background wind field components within the range of 800km radius (r _ vor).

The gray triangles in FIG. 3 indicate the position of the best path set data positioning typhoon, and since this position is the actual position of the typhoon activity, its probability is not at the grid point of the analysis data. The gray large round point represents the center of the real typhoon, namely the grid point closest to the position of the typhoon in the optimal path set, the black large round point represents the center of the searched analysis typhoon, the dotted line ring area represents the maximum vorticity search area, the solid line ring area represents the analysis typhoon area, the black small round point represents the grid point position where the analysis data is decomposed, and the decomposed analysis field is located on the black small round point in the large circle. In the figure, the reanalysis data with 2.5 DEG x 2.5 DEG spatial resolution is taken as an example, and the method is similar if reanalysis data with 1 DEG x 1 DEG spatial resolution is used.

After the wind field range is determined, the wind field decomposition can be carried out on the target area, and a background wind field and a typhoon wind field are separated.

The principle of decomposing and analyzing the data wind field is that the plane of incompressible fluid has no rotational motion and has velocity potential and flow function, the horizontal wind field in the reanalysis data can be regarded as the superposition of the non-rotational motion wind field, the non-scattered motion wind field and the residual error term, the velocity fields of the non-rotational motion wind field and the non-scattered motion wind field can be superposed to obtain the typhoon wind field by calculating the velocity potential and the flow function of the reanalysis data wind field, and the residual error term of the reanalysis velocity field and the typhoon wind field is the atmospheric circulation background wind field.

The specific calculation scheme is that in the range of 800km radius with the center of the typhoon to be analyzed as the center of a circle, a formula is utilizedAndcalculating a non-dispersion motion wind field, wherein psi represents a flow function of non-dispersion wind, and zeta represents relative vorticity;is a translational motion velocity field. At the same time, using the formulaAndcalculating a non-rotational motion wind field, wherein x represents the velocity potential, delta represents the divergence,is a rotational motion velocity field. Typhoon wind field V_TC＝v_ψ+v_χEliminating environmental background wind field V after typhoon wind field_E＝V-V_TC。

The concrete solving steps are as follows:

s1, atmospheric wind field of known meteorological data reanalysis data(radial wind component v and latitudinal wind component u), calculating relative vorticity ζ and divergence δ:

s2, according toAndsolving psi and chi;

s3, according toAndv is obtained_ψAnd v_χ(ii) a (k is a unit vector in the z direction)

S4，V_TC＝v_ψ+v_χFurther, V is obtained_E＝V-V_TC；

The above calculation method is prior art and is used herein to verify the feasibility of the separation typhoon technique.

The specific flow of the typhoon wind field part and the atmospheric circulation background wind field part is divided into meteorological data by utilizing a typhoon wind field separating technology. The analysis data of each standard layer in the atmosphere vertical direction are processed by the method, and the typhoon wind field component of the whole layer of each time-order troposphere and the atmospheric circulation background wind field component can be obtained. The present inventor utilizes Fortran program source code to achieve the purpose of decomposing the atmospheric re-analysis data into typhoon vortex wind field component and atmospheric circulation background wind field component.

It should be noted that, since reanalysis data used in atmospheric science research at present have different spatial resolutions (e.g., reanalysis data of resolutions such as 2.5 ° × 2.5 °, 1 ° × 1 °), when the reanalysis data has low spatial resolution, the spatial resolution of the decomposed typhoon field component is also low, so that the representativeness of the information such as typhoon intensity, influence range and the like is insufficient, in order to solve the problem of weak climatological characteristics of the typhoon field component possibly caused by the method to a certain extent, the invention sets the radius range of the decomposition analysis data field to be a larger threshold (for example 800km), and simultaneously, reanalysis data with higher resolution (such as 1 degree multiplied by 1 degree and above) is proposed to be used, so that more typhoon wind field information in the grid point data is reflected in the separated typhoon components, and a typhoon vortex wind field and an atmospheric environment field background wind field can be more accurately represented. For the selection of the analysis area threshold, the spatial range of the decomposed atmospheric wind field can be determined by adopting a mode of dynamically positioning and analyzing the typhoon scale according to the satellite observation data, so that the purpose of eliminating the typhoon system in the environmental field more accurately is achieved.

In order to verify the effectiveness of the method for eliminating the typhoon field, the inventor provides experimental implementation data. Fig. 4 shows the state before and after decomposing the 850hPa wind field of the troposphere low layer in the northwest pacific and south sea areas and the vorticity field thereof into typhoon vortex and atmospheric background circulation at 8, 27, 12 in 1997.

As can be seen from fig. 4(a), three typhoon systems exist simultaneously on the positive vorticity zone distributed in the latitudinal direction around 20 ° N at this moment, which is also the position of the east asian monsoon wind channel, which is a typical potential field favorable for the generation and development of typhoons, so that the typhoon area is the maximum area of the positive vorticity in the monsoon wind channel. Fig. 4(b) shows the 850hPa wind field and the vorticity field with three typhoons separated, and a comparison with fig. 4(a) shows that the positive vorticity is mainly caused by typhoons. Fig. 4(c) shows the background field portion after the typhoon vortex is removed, and it can be seen that the positive vorticity in the monsoon groove is greatly reduced, but the relevant features of the monsoon groove still remain in the background data.

To illustrate the effect of decomposition on long-time scale climate characterization, FIG. 4(d) shows the mean distribution of 850hPa wind field and vorticity field in the season of typhoon (6-10 months) in 1997. FIG. 4(e) is a seasonal average of isolated typhoon circulation, which is mainly manifested by a significant positive vorticity distribution in the southeast region of the North-West Pacific, which is most active in typhoon activity in the summer and autumn, corresponding to the strongest early nino in 1997The modulation effect on the activity of the northwest Pacific typhoon can be accurately reversedReflecting the climatic properties of the activity in the typhoon season (note: El)During the year, western pacific typhoons frequently move and strong typhoons frequently occur). Fig. 4(f) shows the seasonal average of the background field with the typhoon field removed, and compared to fig. 4(e), the wind speed and positive vorticity in the southeast region of the pacific northwest are reduced by the seasonal average of the typhoon field, while the main large-scale circulating system is still evident. Therefore, the re-analysis data is processed by the processing method, so that the purposes of separating the typhoon related information from the analysis field and effectively retaining the large-scale circulation characteristics in the background field are achieved.

The second step is that: computing absolute vorticity eta of troposphere lower layer 850hPa by utilizing atmospheric circulation background wind field_NOTCAnd convection layer high and low layer 200hPa minus 850hPa vertical wind shear V_shear-NOTC；

The first step is utilized to obtain the data of the large-scale environmental wind field of each layer of the troposphere after eliminating the typhoon wind field, and the absolute vorticity eta of 850hPa can be calculated_NOTCAnd convection layer high and low layer 200hPa minus 850hPa vertical wind shear V_shear-NOTCThese two parameters. Wherein, the absolute vorticity eta of the flow layer lower layer 850hPa_NOTCThe calculation formula is as follows:

wherein thereinAndrespectively showing the latitude wind and the longitude wind of the atmospheric circulation background after eliminating the typhoon wind field on the 850hPa level;

convection layer high and low layer 200hPa minus 850hPa vertical wind shear V_shear-NOTCThe calculation formula of (2) is as follows:

or

WhereinAndrespectively representing the atmospheric circulation background latitude wind and longitude wind after eliminating the typhoon field on the 200hPa level, whereinAndrespectively showing the atmospheric circulation background latitude wind and longitude wind after eliminating the typhoon field on the 850hPa level.

The third step: calculation of 600hPa relative humidity H and typhoon potential intensity V using conventional data_pot；

The relative humidity H of 600hPa does not need to be calculated, and can be directly acquired from meteorological data in a centralized manner. Potential intensity of typhoon V_potThe calculation method can be obtained by referring to the conventional method for calculating the GPI index formula, and all parameters and variables can be directly obtained from meteorological data in a centralized manner.

The fourth step: using the parameter η obtained in the second step_NOTCAnd V_shear-NOTCAnd the parameters H and V obtained in the third step_potCalculating GPI to finally obtain an improved GPI index;

the GPI calculation formula obtained by the new method is as follows:

thus, an improved GPI index can be obtained.

The invention aims to eliminate the influence from a typhoon system in terms of 850hPa absolute vorticity of a troposphere and 200hPa minus 850hPa vertical wind shear of a troposphere when calculating a GPI index, and calculate the GPI index by using element variables without typhoon weather system data such as a typhoon wind field and the like, thereby obtaining an index of potential contribution of a more pure atmospheric marine environment background field to typhoon generation.

Specifically, the method removes the wind field data information of typhoon in the atmospheric circulation, calculates two parameters of absolute vorticity and vertical wind shear by only using the atmospheric background wind field, and substitutes the parameters into the GPI index. The improved GPI index can be considered as potential contribution of a pure environmental background field to generation and activities of a typhoon weather system due to the fact that the improved GPI index does not contain typhoon information interference, and the indication capability of the improved GPI index to the generation relation of the atmospheric marine environmental conditions, typhoons and other marine strong convection weather scale disturbance systems is greatly improved, so that the purpose of objectively and quantitatively and accurately evaluating the influence of the atmospheric marine background field on the typhoon activities is achieved.

In practical application, the improved GPI index can be calculated by removing the typhoon wind field and other information from the analysis data and calculating the GPI using the data from which the typhoon wind field is removed, thereby achieving the similar purpose and expected calculation result to those of the present invention. At present, in addition to the method mentioned in the present invention, it is possible to remove the typhoon wind field part in the analysis data by using a method combining smoothing and filtering techniques, which is as follows:

decomposing an initial wind field V into a basic field V_BAnd a disturbance field V_D：V＝V_B+V_D；

And then decomposing the disturbance field into a background disturbance field and a typhoon disturbance field, wherein the typhoon disturbance field is a typhoon field component to be eliminated. Disturbing typhoon in disturbing field V_TyphoonRemoving to obtain environment wind field V with typhoon removed_E：V_E＝V_B+(V_D-V_TC)＝V-V_TC；

Here, V denotes a vector wind field, and includes two components, i.e., a latitudinal wind u and a latitudinal wind V. The wind field in the technical route is directly represented by the latitudinal and longitudinal winds (u and v in lower case), so it is felt as if it did not correspond.

Formula V_E＝V-V_TCIndicating a corresponding subtraction of vector components (warp and weft), i.e.

Weft wind: u. of_E＝u-u_TC

The meridian wind: v. of_E＝v-v_TC

The two can be combined together by formula V_E＝V-V_TCDenoting, upper case V denotes the wind field vector.

To determine the location of the analytic typhoon (typhoon center), the influence of the distance can be taken into account, adding a distance weight. Calculating the disturbance wind speed V by using the following formula with the grid point closest to the observation typhoon position as the center_DijA centroid position within a range.

Wherein D is 200km, D is 400km,respectively, the longitude and latitude, Delta S, of the center of the typhoon_ijIs the area corresponding to the grid or grid,is the wind speed of the typhoon field, r is the distance of the analysis point from the center position of the typhoon.

The method for removing the typhoon wind field part in the analysis data by using the method of combining the smoothing and filtering technologies is an existing calculation formula, and is not repeated here.

The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only specific embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.