A mesoscale convective system rainstorm early warning method based on environmental condition difference

Abstract

The application discloses a mesoscale convective system rainstorm early warning method based on environmental condition difference, comprising the following steps: S1, determining linear MCS and nonlinear MCS according to the MCS attribute features reaching the standard on the radar and satellite cloud pictures; S2, determining the MCS rainstorms of two forms, namely, linear MCS rainstorm and nonlinear MCS rainstorm, according to different environmental conditions; S3, determining the starting time, strengthening time and duration of the MCS rainstorms of various forms according to the relationship between the attribute features of the MCS of various forms and the rainstorm generation time; and S4, calculating the position and moving direction of the MCS rainstorms of various forms appearing in the MCS according to the relationship between the attribute features of the MCS of various forms and the rainstorm appearing position and moving path. Through the method, a short-impending rainstorm early warning model suitable for the plateau is constructed, the change from 'generalized early warning' to 'precise targeting' is realized, and the timeliness and accuracy of the rainstorm early warning are improved.

Description

Technical Field

[0001] This invention relates to the field of rainstorm early warning technology, specifically to a rainstorm early warning method for mesoscale convective systems based on differences in environmental conditions. Background Technology

[0002] Xining, located in the northeastern part of the Qinghai-Tibet Plateau, is an area prone to concentrated heavy rainfall and disasters. Mesoscale convective systems (MCS) contribute over 90% to heavy rainfall precipitation on average. Current research on plateau MCS largely focuses on the evolution of heavy precipitation caused by their interaction with downstream weather systems after moving off the plateau, with significant shortcomings in capturing the precursory characteristics of MCS formation and development on the plateau. Furthermore, due to the limitations of observation conditions in the complex terrain of the plateau, existing early warning technologies struggle to accurately capture the key dynamic triggering signals of MCS-induced heavy rainfall, resulting in forecast accuracy and early warning lead times consistently falling short of disaster prevention requirements. Therefore, it is urgent to construct a short-term heavy rainfall early warning model adapted to the unique characteristics of the plateau by combining high spatiotemporal resolution satellite observations, radar network data, and encrypted ground monitoring data. Summary of the Invention

[0003] The purpose of this invention is to provide a method for early warning of rainstorms in mesoscale convective systems based on differences in environmental conditions, so as to construct a short-term early warning model for rainstorms adapted to the special characteristics of plateaus, and realize the transformation from "generalized early warning" to "precise targeting", which is conducive to improving the timeliness and accuracy of rainstorm warnings.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A method for early warning of heavy rainfall in mesoscale convective systems based on differences in environmental conditions includes:

[0006] S1. Based on the standard MCS attribute characteristics on radar and satellite cloud images, determine the linear MCS and nonlinear MCS;

[0007] S2. Based on different environmental conditions, determine the two types of MCS rainstorms: linear MCS rainstorms and nonlinear MCS rainstorms.

[0008] S3. Based on the relationship between the characteristics of different MCS attributes and the time of rainstorm occurrence, determine the start, intensification and duration of various MCS rainstorms.

[0009] S4. Based on the relationship between the characteristics of different MCS morphologies and the location and movement path of rainstorms, calculate the location and direction of movement of rainstorms in various MCS morphologies.

[0010] Furthermore, before proceeding to step S1, it is necessary to collect multi-source data such as weather radar, meteorological satellite TBB data, and precipitation data from ground monitoring stations, and conduct preliminary analysis on them. The preliminary analysis includes: identification and attribute characteristic classification of MCS, determination of the environmental conditions for the formation of MCS rainstorms, and establishment of the relationship between MCS and rainstorms.

[0011] Furthermore, the identification and attribute feature classification of the MCS specifically includes:

[0012] Based on meteorological satellite TBB data and using the TR standard, MCS was identified and tracked, and compared and analyzed with radar data.

[0013] The MCS was determined by comprehensively referencing radar reflectivity factor R intensity ≥ 45 dBz and satellite TBB ≤ −32℃.

[0014] The properties and structural features of different morphologies of MCS were calculated. The property features of MCS include minimum TBB value, area and duration, and the corresponding structural features are MCS intensity, range and life history.

[0015] The determination of the environmental conditions for the formation of MCS rainstorms includes environmental conditions such as the influencing system, the dynamics of the ground and upper atmosphere, water vapor, energy and wind field conditions. By analyzing the environmental conditions for the formation of different types of MCS rainstorms, the environmental driving factors for the formation of different types of MCS are established, which becomes the basis for MCS rainstorm early warning.

[0016] The relationship between MCS and heavy rain is clearly defined, including: the relationship between the morphology and intensity of MCS and the amount of heavy rain, and the relationship between the time and duration of precipitation generated by MCS and the start time of heavy rain.

[0017] Furthermore, in step S1, it is determined that when the mature stage of radar and satellite is distributed in a band-like pattern and the influence range is elongated (i.e., the aspect ratio exceeds 3:1), it is a linear MCS. When it is distributed in a blocky pattern and the influence range is more inclined to be approximately elliptical (i.e., the aspect ratio is around 1:1), it is determined to be a nonlinear MCS.

[0018] Furthermore, in step S2, the environmental conditions for linear MCS rainstorms are: strong westerly winds at the upper atmosphere near the subtropical high and in front of the shear line, with convective instability, significant development of vertical vorticity, and strong vertical shear of the upper-level wind field as the main driving forces, and the surface wind field mainly transporting water vapor by southeasterly airflow.

[0019] The environmental conditions for nonlinear MCS-type rainstorms are as follows: when a low trough develops and moves eastward over the plateau, there is a long-term positive vortex and a deep moist layer, and the surface is a southerly airflow formed by the convergence of southeast and southwest airflows.

[0020] Furthermore, step S3 specifically includes:

[0021] When the length of a continuous area with TBB ≤ -32℃ and CR ≥ 45dBz in the MCS exceeds 100km, the starting time of the MCS rainstorm is determined by delaying the start time by 1-2 hours.

[0022] The intensification time of MCS intensity and area increase is delayed by 2-3 hours to determine the intensification time of linear MCS rainstorms, and the duration of the rainstorm is determined by the life history of the MCS.

[0023] The time when the intensity and area of ​​the MCS increase are delayed by 1 hour to determine the intensification time of the nonlinear MCS rainstorm, and the duration of the rainstorm is determined by the life history of the MCS.

[0024] Furthermore, in step S4, the specific steps are as follows: based on the direction of the MCS movement in the previous 30 minutes, the future movement path and direction are obtained by linear extrapolation. At the same time, the rainstorm area is determined according to the MCS position on the satellite cloud image: linear rainstorms are in the third quadrant of the MCS, while nonlinear rainstorms are in the second quadrant.

[0025] Compared with the prior art, the present invention can achieve at least the following beneficial effects:

[0026] 1. Due to the different morphological structures of MCS, there are significant differences in the triggering and intensity evolution of rainstorms. Therefore, this early warning method first classifies the MCS of plateau rainstorms according to morphology, and then quantitatively analyzes circulation indicators such as instability, water vapor transport and dynamic lifting conditions corresponding to different MCS morphologies. It focuses on the differences in environmental conditions and formation mechanisms of rainstorms with different MCS morphologies, providing a foundation for the subsequent establishment of early warning methods.

[0027] 2. Based on the correlation characteristics between different forms of MCS and the onset, intensification, duration, location, and movement path of rainstorms, a refined early warning method based on "form" is established to realize the transformation from "generalized early warning" to "precise targeting". This is conducive to improving the timeliness and accuracy of rainstorm early warning and providing key decision support for disaster prevention and mitigation.

[0028] 3. This early warning method is based on a comprehensive judgment of numerical forecasts, radar echoes, and satellite cloud image monitoring. It can not only display the entire life cycle of the MCS from a macro perspective and judge its movement and development trend, but also accurately capture the intensity changes, internal structure, and core areas of heavy precipitation in the MCS. The combination of "numerical + radar + satellite" not only fits the work habits of forecasters to track in real time, but also improves the accuracy of MCS rainstorm identification and the timeliness of early warning through cross-validation of multi-source data. It is a practical technical means in operational forecasting. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the rainstorm early warning method described in this invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0032] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] Please see Figure 1 This invention provides a method for early warning of heavy rainfall in mesoscale convective systems based on differences in environmental conditions, comprising:

[0034] S1. Based on the standard MCS attribute characteristics on radar and satellite cloud images, linear MCS and nonlinear MCS are determined. In this embodiment, when the mature stage of radar and satellite shows a band-like distribution and the influence range is narrow and long, i.e. the aspect ratio is greater than 3:1, it is determined to be a linear MCS. When it shows a block-like surface distribution and the influence range is more inclined to be approximately elliptical, i.e. the aspect ratio is about 1:1, it is determined to be a nonlinear MCS.

[0035] S2. Based on different environmental conditions, two types of MCS rainstorms are identified: linear MCS rainstorms and nonlinear MCS rainstorms. In this embodiment, the environmental conditions for linear MCS rainstorms are: strong westerly winds at the upper atmosphere near the subtropical high and in front of the shear line, with convective instability, significant development of vertical vorticity, and strong vertical shear of the upper-level wind field as the main driving forces, and the surface wind field mainly transporting water vapor by southeasterly airflow.

[0036] The environmental conditions for nonlinear MCS-type rainstorms are: when a low trough develops and moves eastward over the plateau, there is a long-term positive vortex and a deep moist layer, and the surface is a southerly airflow formed by the convergence of southeast and southwest airflows;

[0037] S3. Based on the relationship between the characteristics of different MCS morphologies and the time of rainstorm occurrence, the start, intensification, and duration of various MCS morphologies of rainstorms are determined. In this embodiment,

[0038] When the length of a continuous area with TBB ≤ -32℃ and CR ≥ 45dBz in the MCS exceeds 100km, the starting time of the MCS rainstorm is determined by delaying the start time by 1-2 hours.

[0039] The intensification time of MCS intensity and area increase is delayed by 2-3 hours to determine the intensification time of linear MCS rainstorms, and the duration of the rainstorm is determined by the life history of the MCS.

[0040] The time when the intensity and area of ​​the MCS increase are delayed by 1 hour to determine the intensification time of the nonlinear MCS rainstorm, and the duration of the rainstorm is determined by the life history of the MCS.

[0041] S4. Based on the relationship between the characteristics of different MCS morphologies and the location and movement path of rainstorms, calculate the location and direction of movement of rainstorms in various MCS morphologies.

[0042] Specifically, in this step, based on the direction of the MCS movement in the previous 30 minutes, the future movement path and direction are obtained by linear extrapolation. If the path is northwest or southwest, the intensity of the rainstorm is determined to be strong (hourly rainfall intensity ≥ 20 mm). At the same time, the rainstorm area is determined based on the position of the MCS on the satellite cloud image: linear rainstorms are in the third quadrant of the MCS, and nonlinear rainstorms are in the second quadrant.

[0043] It should be noted that before proceeding to step S1, it is necessary to collect multi-source data such as weather radar, meteorological satellite TBB data, and precipitation data from ground monitoring stations. Preferably, data can be obtained from Doppler weather radar, high-resolution equivalent blackbody temperature (TBB) data and infrared cloud images from the FY geostationary meteorological satellite provided by the National Satellite Meteorological Center of the China Meteorological Administration, and precipitation data from encrypted ground monitoring stations. The data obtained are data from a specific location within a certain time period (e.g., Doppler weather radar data from Xining from 2016 to 2023). Preliminary analysis can be performed on this data, which includes: identification and attribute characteristic classification of MCS, determination of the environmental conditions for MCS rainstorm formation, and establishment of the relationship between MCS and rainstorm.

[0044] More specifically, the identification and attribute feature classification of the MCS mentioned above includes:

[0045] a. Identify and track MCS based on meteorological satellite TBB data and TR standards, and compare and analyze them with radar data (CR, R, etc.);

[0046] b. The MCS is determined by comprehensively referring to radar reflectivity factor R intensity ≥ 45dBz and satellite TBB ≤ −32℃.

[0047] c. Calculate the properties and structural features of different morphologies of MCS. The property features of MCS include minimum TBB value, area and duration, and the corresponding structural features are MCS intensity, range and life history.

[0048] The TBB value is based on satellite infrared channel observation data. First, the TBB closed contour area that meets the MCS determination criterion of -32℃ is extracted. Then, the lowest value in the area is selected as the minimum TBB value. At this time, the smaller the TBB value, the stronger the MCS intensity. On the radar, the maximum value of the combined reflectivity factor (CR) is used as the intensity. At the same time, the effective area of ​​TBB≤-32℃ is accumulated by pixel surface to obtain the real-time coverage area of ​​MCS, which is used to characterize the spatial range of MCS. On the radar, the area of ​​CR≥45dBz is the MCS range. Here, the moment when the TR criterion is first met is defined as the MCS generation moment, and the moment when the TR criterion is no longer met (moving out of the influence area) is defined as the MCS extinction moment. The time period between the generation moment and the extinction moment is the MCS life history. After comparing and analyzing the results obtained by satellite and radar, the plateau rainstorm MCS is classified into two categories, linear and nonlinear, according to the classification criteria of Orlanski (1975) mesoscale system and the MCS morphology and aspect ratio on radar and satellite.

[0049] The determination of the environmental conditions for the formation of MCS rainstorms includes environmental conditions such as the influencing system, the dynamics of the ground and upper atmosphere, water vapor, energy and wind field conditions. By analyzing the environmental conditions for the formation of different types of MCS rainstorms, the environmental driving factors for the formation of different types of MCS are established, which becomes the basis for MCS rainstorm early warning.

[0050] Among them, the influencing system is mainly the weather system at the upper air 500-700 hPa, the dynamic conditions are mainly physical quantities such as wind field, vorticity field, and vertical velocity, and the water vapor conditions are mainly wind field, water vapor flux and water vapor flux divergence. At the same time, the energy characterization quantities such as potential vorticity and pseudo equivalent potential temperature are used to calculate the change values ​​of MCS rainstorms during the formation-intensification-weakening period, so as to determine the difference in environmental conditions for the generation of linear and nonlinear MCS rainstorms.

[0051] The relationship between MCS and rainstorms is clearly defined, including: the relationship between the morphology and intensity of MCS and the amount of rainstorms, and the relationship between the time and duration of precipitation generated by MCS and the start time of rainstorms. This allows for the acquisition of applicable MCS-rainstorm relationship indicators, as well as the start and intensification times, rainstorm areas, and movement directions for various types of MCS rainstorms.

[0052] In practical applications, the rainstorm warning method described in this invention is applied to rainstorm weather during the flood season, providing real-time services for short-term rainstorm warnings and process review. When the MCS (Mean Cross-Sectional Response) is identified on radar and satellite cloud images and meets the warning triggering conditions, the warning information is promptly sent through the business platform, and the internal "call-and-response" mechanism is activated simultaneously. In conjunction with local progressive meteorological warning service standards, targeted warning information is pushed to the meteorological service department 1-2 hours in advance, and delivered through multiple channels such as SMS. After each rainstorm process, the accuracy of MCS identification and the advance warning are reviewed by comparing the actual precipitation data. The parameter thresholds of different MCS forms are dynamically optimized, and the accuracy of the warning is gradually improved, thus establishing a complete business chain from technical assessment to disaster prevention implementation.

[0053] The following are examples of the application of the early warning method described in this invention in practice:

[0054] This early warning method was applied during the heavy rainfall in Xining in 2024. The following is the early warning process for the torrential rain on September 3-4, 2024:

[0055] (1) On September 2, the forecast conclusions of the European Centre for Medium-Range Weather Forecasts (ECMWF) were used first. Based on the environmental conditions for the formation of various MCS rainstorms and the key parameters such as the corresponding upper-level weather systems, dynamic conditions, water vapor conditions, vertical wind shear and lifting mechanisms, the environmental conditions on the night of the 3rd were determined to be: the subtropical high retreated eastward, and its edge was a clear southwest warm and humid airflow, which formed convective instability and significant development of vertical vorticity over eastern Qinghai. There was a strong vertical shear in the upper-level wind field, and the surface wind field was a significant southeast airflow transporting water vapor. These conditions indicate that this process meets the environmental conditions for linear MCS rainstorms.

[0056] (2) During the process from September 3 to 4, based on the Xining Doppler weather radar products and FY meteorological satellite data, the morphological attributes and change characteristics of linear MCS were analyzed, and the time of occurrence, intensification and weakening of the rainstorm were predicted: around 22:00 on the 3rd, the continuous area length of the MCS with TBB≤-32℃ and CR≥45dBz exceeded 100km. According to the warning method, it was postponed by 1-2 hours. Therefore, the predicted start time of the rainstorm was around 23:00-00:00, and it actually started at 23:00. At the same time, the time when the MCS intensity increased and the area increased was at 00:00. According to the warning method, it was postponed by 2-3 hours to the time when the MCS rainstorm intensified. Therefore, the predicted time when the rainstorm intensified significantly was 02:00-03:00, and the maximum hourly precipitation occurred at 02:00. Since the warning method takes the life history of the MCS as the duration of the rainstorm, the MCS actually moved out of Xining at 05:00, and the intensity of the rainstorm weakened significantly at 06:00.

[0057] (3) During the process from September 3 to 4, based on the fact that the MCS moved from northwest to southeast from 21:30 to 22:00, which is the northwest path, the future movement path and direction were obtained by linear extrapolation. Since this process is the northwest path, the intensity of the rainstorm was determined to be strong (hourly rainfall intensity ≥ 20 mm). Furthermore, the rainstorm area was determined to be in the third quadrant of the MCS based on the MCS position on the satellite cloud image, which is consistent with the actual monitoring results.

[0058] Based on the results obtained from the above early warning methods, the Xining Meteorological Observatory accurately determined the location and intensity of heavy rainfall, and promptly guided, issued or upgraded high-level rainstorm warning signals, with an advance warning time of 1-3 hours and an accuracy rate of 90%.

[0059] Although the invention has been described herein with reference to several illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope and spirit of the principles disclosed herein. More specifically, various modifications and improvements can be made to the components or layout of the subject matter arrangement within the scope of the disclosure, drawings, and claims. Besides modifications and improvements to the components or layout, other uses will be apparent to those skilled in the art.

Claims

1. A method for early warning of heavy rainfall in mesoscale convective systems based on differences in environmental conditions, characterized in that, include: S1. Based on the standard MCS attribute characteristics on radar and satellite cloud images, determine the linear MCS and nonlinear MCS; S2. Based on different environmental conditions, determine the two types of MCS rainstorms: linear MCS rainstorms and nonlinear MCS rainstorms. S3. Based on the relationship between the characteristics of different MCS attributes and the time of rainstorm occurrence, determine the start, intensification and duration of various MCS rainstorms. S4. Based on the relationship between the characteristics of different MCS morphologies and the location and movement path of rainstorms, calculate the location and direction of movement of rainstorms in various MCS morphologies.

2. The method for early warning of heavy rainfall in mesoscale convective systems based on differences in environmental conditions according to claim 1, characterized in that: Before proceeding to step S1, it is necessary to collect multi-source data such as weather radar, meteorological satellite TBB data, and precipitation data from ground monitoring stations, and conduct preliminary analysis on them. The preliminary analysis includes: identification and attribute characteristic classification of MCS, determination of the environmental conditions for the formation of MCS rainstorms, and establishment of the relationship between MCS and rainstorms.

3. The method for early warning of heavy rainfall in mesoscale convective systems based on differences in environmental conditions according to claim 2, characterized in that: The identification and attribute feature classification of the MCS specifically includes: Based on meteorological satellite TBB data and using the TR standard, MCS was identified and tracked, and compared and analyzed with radar data. The MCS was determined by comprehensively referencing radar reflectivity factor R intensity ≥ 45 dBz and satellite TBB ≤ −32℃. The properties and structural features of different morphologies of MCS were calculated. The property features of MCS include minimum TBB value, area and duration, and the corresponding structural features are MCS intensity, range and life history. The determination of the environmental conditions for the formation of MCS rainstorms includes environmental conditions such as the influencing system, the dynamics of the ground and upper atmosphere, water vapor, energy and wind field conditions. By analyzing the environmental conditions for the formation of different types of MCS rainstorms, the environmental driving factors for the formation of different types of MCS are established, which becomes the basis for MCS rainstorm early warning. The relationship between MCS and heavy rain is clearly defined, including: the relationship between the morphology and intensity of MCS and the amount of heavy rain, and the relationship between the time and duration of precipitation generated by MCS and the start time of heavy rain.

4. The method for early warning of heavy rainfall in mesoscale convective systems based on differences in environmental conditions according to claim 1, characterized in that: In step S1, it is determined that when the mature stage of radar and satellite is distributed in a band-like pattern and the influence range is in a narrow and long shape, i.e. the aspect ratio is greater than 3:1, it is a linear MCS. When it is distributed in a blocky pattern and the influence range is more inclined to be approximately elliptical, i.e. the aspect ratio is about 1:1, it is determined to be a nonlinear MCS.

5. The method for early warning of heavy rainfall in mesoscale convective systems based on differences in environmental conditions according to claim 1, characterized in that: In step S2, the environmental conditions for linear MCS rainstorms are: strong westerly winds in the upper atmosphere near the subtropical high and in front of the shear line, with convective instability, significant development of vertical vorticity, and strong vertical shear of the upper-level wind field as the main driving forces, and the surface wind field mainly transporting water vapor by southeasterly airflow. The environmental conditions for nonlinear MCS-type rainstorms are as follows: when a low trough develops and moves eastward over the plateau, there is a long-term positive vortex and a deep moist layer, and the surface is a southerly airflow formed by the convergence of southeast and southwest airflows.

6. The method for early warning of heavy rainfall in mesoscale convective systems based on differences in environmental conditions according to claim 1, characterized in that: Step S3 specifically includes: When the length of a continuous area with TBB ≤ -32℃ and CR ≥ 45dBz in the MCS exceeds 100km, the starting time of the MCS rainstorm is determined by delaying the start time by 1-2 hours. The intensification time of MCS intensity and area increase is delayed by 2-3 hours to determine the intensification time of linear MCS rainstorms, and the duration of the rainstorm is determined by the life history of the MCS. The time when the intensity and area of ​​the MCS increase are delayed by 1 hour to determine the intensification time of the nonlinear MCS rainstorm, and the duration of the rainstorm is determined by the life history of the MCS.

7. The method for early warning of heavy rainfall in mesoscale convective systems based on differences in environmental conditions according to claim 1, characterized in that: In step S4, the specific steps are as follows: based on the direction of the MCS movement in the previous 30 minutes, the future movement path and direction are obtained by linear extrapolation. At the same time, the rainstorm area is determined according to the MCS position on the satellite cloud image: linear rainstorms are in the third quadrant of the MCS, and nonlinear rainstorms are in the second quadrant.

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