A downburst warning method and device

Abstract

The present application discloses a downburst early warning method and device, comprising: starting from the generation principle of downburst, inverting the characteristic data of convective cells through Doppler radar to obtain 1km*1km*0.5km three-dimensional wind field data, including horizontal wind speeds u and v, and using the horizontal divergence and horizontal vorticity calculated by the three-dimensional wind field data; then calculating the downburst storm center position and other information through the horizontal divergence and horizontal vorticity characteristics, and being able to issue an early warning message containing the downburst storm center position information at least two volume scan times in advance, which is conducive to evacuating people in key areas and reducing casualties and property losses caused by extreme disasters.

Description

Technical Field

[0001] The present application relates to the technical field of meteorological disaster prevention and mitigation, and in particular to a downburst early warning method and device. Background Art

[0002] A downburst refers to a localized strong downdraft in a thunderstorm cloud. When it reaches the ground, it will produce a straight-line strong wind. The closer to the ground, the stronger the wind speed will be. The maximum ground wind speed can reach level 15. It is a sudden, localized, low-probability, severe convective weather. It is generally believed that the formation of a downburst is closely related to the updraft and collapse of the thunderstorm cloud top. During its updraft and updraft process, the updraft obtains horizontal momentum from the movement of the upper atmosphere. As the updraft height increases, the kinetic energy of the updraft is converted into potential energy (manifested as heavy and cold cloud tops) and is stored. Later, once the cloud top collapses rapidly, the potential energy is converted back into downdraft. The downdraft absorbs huge horizontal momentum during the descent process and rapidly propels forward. When it reaches the ground, a downburst can be formed.

[0003] The reason why downbursts really attract people's attention is that downbursts can cause damage comparable to that of tornadoes.

[0004] In the prior art, some prediction programs have been designed based on the characteristics of downburst convective cells in existing cases using Doppler radar data. However, they do not predict the location of the storm center of the downburst, making it impossible to predict the affected area and evacuate people in the potentially affected area, which can easily cause casualties and property losses. Summary of the invention

[0005] Based on this, the present application provides a downburst early warning method and device to solve the problem in the prior art that the downburst storm center cannot be predicted.

[0006] In a first aspect, an embodiment of the present application provides a downburst early warning method, the method comprising:

[0007] Obtaining the early warning range determined by the radar station and monitoring the convective cells that meet the key monitoring conditions that appear within the early warning range;

[0008] Collecting and calculating characteristic data of the convection cell;

[0009] When the characteristic data meets the condition for forming a downburst, determining whether the characteristic data of the convective cell meets the inversion condition;

[0010] If the conditions are met, the three-dimensional wind field data of the convective cell is obtained by inverting the characteristic data, and the horizontal divergence and horizontal vorticity are calculated by the three-dimensional wind field data;

[0011] Using the horizontal divergence to judge, if a convergence center stronger than the surrounding area appears at the second height, then continue to judge whether there is a convergence center stronger than the surrounding area at the third height, and a divergence center appears in the downwind direction or forward direction of the convergence center;

[0012] If there is a convergence center at the third height that is stronger than the surrounding area, and a divergence center appears in the downwind direction or forward direction of the convergence center, then it is determined whether the convective cell has the preliminary conditions for a strong downburst. If so, the horizontal vorticity is used to calculate the moving direction of the storm center and determine the location information of the storm center;

[0013] Calculate the reflectivity core height and determine whether the reflectivity core height drops by more than a threshold value at least two volume scan times after the reflectivity core height is higher than the first height;

[0014] If it occurs, the automatic warning program is started and a warning message containing the location information of the storm center is issued.

[0015] In a possible implementation, the key monitoring conditions include:

[0016] The reflectivity intensity of the central area of ​​the convection monomer at the first body scan moment and the second body scan moment exceeds the reflectivity intensity threshold, and the area where the reflectivity intensity of the central area of ​​the convection monomer at the second body scan moment exceeds the reflectivity intensity threshold is larger than the area in the first body scan moment, wherein the first body scan moment and the second body scan moment are continuous.

[0017] In a possible implementation manner, the calculating the characteristic data of the convection cell includes:

[0018] The upper horizontal wind speed and the vertical shear of wind speed are calculated using the sounding data within the time threshold;

[0019] When the time threshold is exceeded, the high-altitude data output by the weather forecast model are used to calculate the high-altitude horizontal wind speed and the vertical shear of the wind speed.

[0020] In a possible implementation, the conditions for forming a downburst include:

[0021] The horizontal wind speed at the second height is less than the wind speed threshold, the difference between the horizontal wind speed at the third height and the horizontal wind speed at the second height is less than the first wind speed difference threshold, and the difference between the horizontal wind speed at the third height and the horizontal wind speed at the fourth height is less than the second wind speed difference threshold.

[0022] In a possible implementation, the inversion condition includes:

[0023] The echo top height exceeds the height threshold and the reflectivity intensity of the central area of ​​the convective cell exceeds the reflectivity intensity threshold, and the area where the radar basic reflectivity reaches the basic reflectivity threshold exceeds the area threshold within the warning range.

[0024] In a possible implementation, the preconditions for the strong downburst include:

[0025] The maximum updraft velocity at the second altitude is at least the first velocity threshold, the updraft velocity at the third altitude is at least the second velocity threshold, the downdraft velocity is at least the first velocity threshold, and the updraft velocity at the first altitude is at least the third velocity threshold, and the downdraft velocity is at least the fourth velocity threshold.

[0026] In a possible implementation, the reflectivity core height is obtained by the following steps:

[0027] The maximum reflectivity is calculated layer by layer from the bottom layer height, and the area corresponding to the difference between the reflectivity of each height being at least the maximum reflectivity and a reflectivity value of at most three is calculated, and the height corresponding to the maximum area is determined as the reflectivity core height.

[0028] In a possible implementation, the warning prompt message further includes:

[0029] The occurrence time information of the strong disaster-causing downburst.

[0030] In a second aspect, an embodiment of the present application provides a downburst warning device, the device comprising:

[0031] The monitoring unit is used to obtain the early warning range determined by the radar station and monitor the convective cells that meet the key monitoring conditions that appear within the early warning range.

[0032] The first calculation unit is used to collect and calculate the characteristic data of the convection cell.

[0033] The first judgment unit is used to judge whether the characteristic data of the convective cell meets the inversion condition when the characteristic data meets the condition for forming a downburst.

[0034] The second calculation unit is used to obtain the three-dimensional wind field data of the convection cell by inverting the characteristic data if the judgment result of the first judgment unit is satisfied, and calculate the horizontal divergence and horizontal vorticity by using the three-dimensional wind field data.

[0035] The second judgment unit is used to make a judgment using the horizontal divergence. If a convergence center stronger than the surrounding area appears at the second height, it continues to judge whether there is still a convergence center stronger than the surrounding area at the third height, and a divergence center appears in the downwind direction or forward direction of the convergence center.

[0036] The third judgment unit is used to judge whether the convective cell has the preliminary conditions of a strong disaster-causing downburst if the judgment result of the second judgment unit is that the convergence center exists and the divergence center appears.

[0037] A determination unit is used to calculate the moving direction of the storm center and determine the position information of the storm center by using the horizontal vorticity if the determination result of the third determination unit is yes.

[0038] The fourth judgment unit is used to calculate the reflectivity core height and judge whether the reflectivity core height drops by more than a threshold value at least two body scanning times after the reflectivity core height is higher than the first height.

[0039] The early warning unit is used to start the automatic early warning program and send out an early warning prompt message containing the storm center location information if the judgment result of the fourth judgment unit is that the storm has occurred.

[0040] In a third aspect, an embodiment of the present application provides a device, comprising a memory and a processor, wherein the memory is used to store instructions or codes, and the processor is used to execute the instructions or codes so that the device executes the downburst warning method described in any one of the first aspects above.

[0041] In a fourth aspect, an embodiment of the present application provides a computer storage medium, wherein the computer storage medium stores a code, and when the code is executed, a device executing the code implements the downburst warning method described in any one of the first aspects above.

[0042] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0043] In the embodiment of the present application, a downburst early warning method and device are provided. When executing the method, the convective cells are first monitored and characteristic data are calculated. Then, the three-dimensional wind field data is inverted based on the characteristic data and the horizontal divergence and horizontal vorticity are calculated. Then, it is determined whether the strong disaster-causing downburst conditions are met based on the horizontal divergence. The storm center direction and location information are calculated using the horizontal vorticity. Finally, an early warning message containing the storm center location information is sent. In this way, by sending an early warning message containing the storm center location information, people near the storm center can be evacuated in time, thereby achieving the effect of reducing casualties and property losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in this embodiment or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 Flow chart of severe downburst warning for this application;

[0046] Figure 2 A flowchart of a strong disaster-causing downburst warning for an embodiment of the present application scenario;

[0047] Figure 3 The radar warning range of the weather station where the downburst occurred on May 14, 2021;

[0048] Figure 4 This is the vertical distribution map of wind speed at the Hangzhou radiosonde station during the downburst that occurred on May 14, 2021;

[0049] Figure 5a This is a schematic diagram of the horizontal divergence of the downburst at an altitude of 3000m at 21:54 on May 14, 2021;

[0050] Figure 5b This is a schematic diagram of the horizontal divergence of the downburst at an altitude of 5000m at 21:54 on May 14, 2021;

[0051] Figure 6a This is a schematic diagram of the vertical velocity of the downburst at an altitude of 3000m at 21:54 on May 14, 2021;

[0052] Figure 6b This is a schematic diagram of the vertical velocity of the downburst at an altitude of 5000m at 21:54 on May 14, 2021;

[0053] Figure 6c This is a schematic diagram of the vertical velocity of the downburst at an altitude of 7000m at 21:54 on May 14, 2021;

[0054] Figure 7 This is a schematic diagram of the horizontal vorticity of the downburst at an altitude of 3000 meters at 21:54 on May 14, 2021;

[0055] Figure 8 This is a schematic diagram of the structure of the downburst warning device provided in this application. DETAILED DESCRIPTION

[0056] In the prior art, the static characteristic data returned by Doppler radar data are analyzed to calculate the intensity of the downburst and the characteristics before the downburst is inferred from the ground disaster characteristics. Some prediction programs are designed for the static characteristics of the downburst convective cells in existing cases based on the characteristics before formation.

[0057] However, the inventors found that the method of providing application results based on a limited number of existing cases cannot predict the location of the storm center of the downburst because the location of the case and the ground disaster situation are known in advance, so it is impossible to evacuate people in the possible disaster-stricken areas, which is likely to cause casualties and property losses.

[0058] Based on this, in order to predict the location of the center of a downburst storm, an early warning method and device for a downburst is provided in an embodiment of the present application. When executing the method, the convective cells are first monitored and characteristic data is calculated. Then, the three-dimensional wind field data is inverted based on the characteristic data and the horizontal divergence and horizontal vorticity are calculated. Then, the horizontal divergence is used to determine whether the conditions for a strong downburst are met. The horizontal vorticity is used to calculate the direction and location information of the storm center. Finally, an early warning message containing the location information of the storm center is sent. In this way, by sending the early warning message, people near the center of the storm can be evacuated in time, thereby reducing casualties and property losses.

[0059] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0060] See also Figure 1 , Figure 1 The flowchart of the downburst warning method provided in the embodiment of the present application includes the following steps:

[0061] S101: Obtaining an early warning range determined by a radar station and monitoring convective cells that meet key monitoring conditions and appear within the early warning range.

[0062] Among them, the warning range refers to the range that can be monitored by the radar determined according to the address of the radar station, and the convective cell refers to a single convective activity that forms a thunderstorm (multi-cell thunderstorm, air mass thunderstorm or irregular multiple cells).

[0063] The key monitoring conditions include: the reflectivity intensity of the center of the convective cell at the first body scan moment and the second body scan moment exceeds the reflectivity intensity threshold, and the area where the reflectivity intensity of the central area of ​​the convective cell at the second body scan moment exceeds the reflectivity intensity threshold is larger than the area in the first body scan moment, the first body scan moment and the second body scan moment are continuous, and the body scan moment refers to the time when the radar enters the body scan mode and performs a data scan, which is generally 6 minutes.

[0064] S102: Collect and calculate characteristic data of the convection cell.

[0065] Wherein, the characteristic data is collected by Doppler radar.

[0066] The calculation of the characteristic data includes calculating the high-altitude horizontal wind speed and the vertical shear of the wind speed using the sounding data within the time threshold, and calculating the high-altitude horizontal wind speed and the vertical shear of the wind speed using the high-altitude data output by the weather forecast model when the time threshold is exceeded.

[0067] The sounding data refers to the high-altitude meteorological data collected by sounding balloons.

[0068] The sounding data are obtained through the observation station closest to the radar station.

[0069] The high-altitude data output by the weather forecast model refers to simulated high-altitude meteorological data obtained through discretization calculation of a nonlinear system.

[0070] The vertical shear refers to the change of wind speed or wind direction with height in a direction perpendicular to the ground surface.

[0071] S103: When the characteristic data meets the conditions for forming a downburst, it is determined whether the characteristic data of the convective cell meets the inversion conditions. If so, the process proceeds to step 104.

[0072] This step is to judge the nature of the convective cell. Ordinary convective cells do not require warnings, but when a convective cell meets the conditions for forming a downburst, a natural disaster may occur.

[0073] The purpose of judging whether the characteristic data of the convection cell meets the inversion conditions is that when the characteristic data of the convection cell does not meet the inversion conditions, it means that no natural disasters will occur in a short period of time, and when the inversion conditions are met, it means that the probability of natural disasters occurring in a short period of time is greatly increased.

[0074] In a possible implementation, the conditions for forming a downburst include:

[0075] The horizontal wind speed at the second height is less than the wind speed threshold, the difference between the horizontal wind speed at the third height and the horizontal wind speed at the second height is less than the first wind speed difference threshold, and the difference between the horizontal wind speed at the third height and the horizontal wind speed at the fourth height is less than the second wind speed difference threshold.

[0076] The inversion conditions include: the echo top height exceeds the height threshold and the reflectivity intensity in the central area of ​​the convective cell exceeds the reflectivity intensity threshold, and the area where the radar basic reflectivity reaches the basic reflectivity threshold exceeds the area threshold in the warning area, wherein the echo top height refers to the height at which the reflectivity detected by the radar has an intensity greater than a certain threshold, and the threshold is set according to actual conditions.

[0077] S104: If the inversion condition is met, the three-dimensional wind field data of the convective cell is inverted using the characteristic data and the horizontal divergence D and the horizontal vorticity ζ are calculated.

[0078] The three-dimensional wind field data of the convective cell is obtained by inverting the characteristic data because subsequent judgment cannot be made directly through the convective cell characteristic data, so horizontal divergence and horizontal vorticity are needed as reference data.

[0079] For example, the three-dimensional wind field data includes horizontal wind field u and v data.

[0080] The horizontal divergence D is calculated by the following formula:

[0081]

[0082] The horizontal vorticity ζ is calculated by the following formula:

[0083]

[0084] Among them, u is the wind speed in the x-axis direction, and v is the wind speed in the y-axis direction. Generally speaking, the x-axis represents the tangent direction of the latitude circle (positive from west to east), and the y-axis represents the tangent direction of the meridian circle (positive from south to north). The unit is s -1 .

[0085] S105: Determine whether a convergence center stronger than the surrounding area appears at the second height. If so, proceed to step S106.

[0086] The basis for the judgment is the horizontal divergence D mentioned above.

[0087] The convergence center refers to the airflow flowing from the surroundings to the center.

[0088] Since the generation of a downburst first requires the existence of an updraft, this step is to determine whether an updraft occurs.

[0089] S106: Determine whether there is still a convergence center at the third height that is significantly stronger than the surrounding area, and whether a significantly stronger divergence center appears in the downwind direction or forward direction of the convergence center. If so, proceed to step S107.

[0090] The basis for the judgment is the horizontal divergence D, and the third height value is greater than the second height value.

[0091] The divergence center refers to the airflow flowing from the center to the surroundings.

[0092] Since the occurrence of downburst requires not only the existence of updrafts but also downdrafts, this step is to determine whether downdrafts occur.

[0093] S107: Determine whether the convective cell has the preliminary conditions for a strong downburst, if so, proceed to step S108.

[0094] The strong disaster-causing downburst refers to the downburst that causes strong geological disasters.

[0095] This step is to determine the level of disaster. Any downburst will cause a certain degree of geological disaster, but strong downbursts have a wider impact range and a higher level of disaster, so more effective early warning is needed.

[0096] In a possible implementation, the preconditions for the strong downburst include:

[0097] The maximum rising air flow velocity at the second height is at least the first speed threshold, the rising air flow velocity at the third height is at least the second speed threshold, the downdraft air flow velocity is at least the first speed threshold, and the rising air flow velocity at the first height is at least the third speed threshold, and the downdraft air flow velocity is at least the fourth speed threshold, the first height value is greater than the third height value, and the third height value is greater than the second height value.

[0098] S108: Calculate the moving direction of the storm center using the horizontal vorticity ζ and determine the position information of the storm center.

[0099] In a possible implementation, the moving direction of the storm center is determined by the direction of the horizontal vorticity vector.

[0100] The storm center location information is calculated based on the wind speed and the moving direction of the storm center.

[0101] The storm center location information may be coordinates, or the name of the disaster-stricken area may be given based on the coordinates, or may be other forms that can represent location information.

[0102] S109: Calculate and determine the reflectivity core height.

[0103] Specifically, it includes: calculating the maximum reflectivity layer by layer from the bottom layer height, and calculating the area corresponding to the difference between the reflectivity of each height and the reflectivity value of at most three, and determining the height corresponding to the maximum area as the reflectivity core height.

[0104] The reflectivity value is at most three because when the value is too large, it is impossible to distinguish each height according to the area corresponding to the difference, resulting in inaccurate determination of the reflectivity core height, thereby reducing the effectiveness of the warning message.

[0105] In a possible implementation, the maximum reflectivity value may be calculated layer by layer from the bottom layer height or for random height layers, or may be calculated layer by layer from the top layer height or for random height layers.

[0106] S110: Determine whether the reflectivity core height drops by more than a threshold value at least two volume scan times after the reflectivity core height is higher than the first height. If so, proceed to S111.

[0107] In one possible implementation, each body scan takes 6 minutes.

[0108] The decrease in the reflectivity core height occurs within at least two volume scan times, which represents the speed of downdraft. Too fast a speed of downdraft is a precursor to a downburst. When this feature appears, it indicates that a strong and disastrous downburst will occur at the center of the storm.

[0109] S111: Starting an automatic warning program to issue a warning message containing the storm center location information.

[0110] For example, the sending of the prompt message includes sending it to all user terminals in the disaster-stricken area, and can also be sent to any device that can prompt disaster victims with disaster information, such as a mobile phone, a television or a computer.

[0111] The warning message may also include the time information of the downburst occurrence, and may also include other data information calculated using the three-dimensional wind field data mentioned in the method.

[0112] All relevant thresholds mentioned in the embodiments of the present application can be pre-defined according to actual needs.

[0113] The embodiment of the present application predicts the center position of a convective cell storm and sends a warning message containing the storm center position information, which helps to evacuate people near the storm center in advance and reduce casualties and economic losses.

[0114] In order to verify the actual effect of the method described in this application, see Figure 2 , which is a flow chart of providing a strong disaster-causing downburst warning in an embodiment of the present application scenario.

[0115] S201: Determine the monitoring and early warning range and the existence of convective cells that meet the key monitoring conditions.

[0116] like Figure 3 As shown, after the monitored warning area is determined, the convective cell enters the warning area, and the reflectivity intensity threshold is taken as 55dBZ. The reflectivity intensity of the central area of ​​the radar puzzle convective cell of the convective cell at 21:20 and 21:30 exceeds 55dBZ, and the area exceeding 55dBZ at 21:30 is larger than the area exceeding 55dBZ at 21:20, so the convective cell is monitored in key areas.

[0117] S202: According to the sounding station data, the convective cell meets the downburst formation conditions.

[0118] The time threshold is taken as four hours. Since the most recent sounding data were obtained within four hours, the data from the nearby Hangzhou sounding station are selected to determine whether the convective cell characteristic data meet the conditions for downburst formation.

[0119] The second height value is 3000m, the third height value is 5000m, the fourth height value is 10000m, the wind speed threshold is 20m / s, the first wind speed difference threshold is 10m / s, and the second wind speed difference threshold is 12m / s. Figure 4 Judging from the data of the sounding station:

[0120] (1) The horizontal wind speed at an altitude of 3000m is 15m / s, less than 20m / s;

[0121] (2) The difference between the horizontal wind speed at 5000m and 3000m is 4m / s, which is less than 10m / s;

[0122] (3) The difference between the horizontal wind speed at an altitude of 5000m and that at an altitude of 10000m is 10m / s, which is less than 12m / s.

[0123] Since the above-mentioned downburst formation conditions are met, the process proceeds to step S203.

[0124] S203: Calculate and obtain the characteristic data of the convection cell to meet the inversion conditions, start the three-dimensional wind field inversion program, and obtain its horizontal wind field u, v data.

[0125] Take the basic reflectivity threshold as 50dBZ, the height threshold as 15000m, and the area threshold as 100km 2, based on the data observed by the Hangzhou radar station closest to the convective cell, calculate the area where the basic reflectivity of the convective cell reaches 50dBZ. When the area exceeds 100km 2 A vertical section is made from the echo center and the echo top height is calculated. When the echo top height exceeds 15000m, it can be determined that the convective cell characteristic data meets the inversion conditions. At this moment, i.e. 21:30, the program for inverting the three-dimensional wind field from Doppler radar data is started, and the horizontal wind field u and v data of 1km*1km*0.5km are inverted.

[0126] S204: Calculate the horizontal divergence and horizontal vorticity, and find that there are convergence centers that are stronger than the surrounding areas at both 3000m and 5000m altitudes, and there is a significantly stronger divergence center in the downwind direction or forward direction of the convergence center at an altitude of 5000 meters.

[0127] The horizontal divergence and horizontal vorticity are calculated using the inverted horizontal wind field u, v data.

[0128] Use the horizontal divergence to determine whether there is a convergence center at 3000m that is significantly stronger than the surrounding area ( Figure 5a ), if yes, continue to determine whether there is still a convergence center at 5000m that is significantly stronger than the surrounding areas, and whether there is a significantly stronger divergence center in the downwind direction or forward direction of the convergence center ( Figure 5b ). At 21:54, both conditions above are met.

[0129] S205: Obtaining, through radar data, the preliminary conditions that the convective cell has a strong disaster-causing downburst.

[0130] Take the first altitude value as 7000m, the first speed threshold as 4m / s, the second speed threshold as 10m / s, the third speed threshold as 15m / s, and the fourth speed threshold as 6m / s. The maximum updraft speed at an altitude of 3000m is determined by radar data to be greater than or equal to 4m / s. Figure 6a ); at an altitude of 5000m, the rising air velocity is greater than or equal to 10m / s, and the sinking air velocity is greater than or equal to 4m / s ( Figure 6b ); 7000m altitude rising air velocity is greater than or equal to 15m / s, sinking air velocity is greater than or equal to 6m / s ( Figure 6c ). At 21:54, strong updrafts appeared, which provided the preliminary conditions for a strong downburst that could cause disasters.

[0131] S206: Using the horizontal vorticity to determine the moving direction of the storm center and calculate the storm center position information.

[0132] At 21:54, the horizontal vorticity at 3000m was located in the right front of the storm ( Figure 7), from which it can be deduced that the storm center will move to the right at 22:00. The storm center position is obtained by first multiplying the wind speed by time to obtain the storm center moving distance, and then combining the above directions to obtain the comprehensive result.

[0133] S207: Determine the reflectivity core height.

[0134] Take the reflectivity value as 2dBZ, the threshold as 3.5km, calculate the maximum reflectivity maxdBZ of each layer from the bottom layer upward, and calculate the area where the reflectivity is greater than or equal to (max-2)dBZ. If the height maxdBZ and the area of ​​a layer are both greater than other layers, the layer is determined as the reflectivity core height (HGT), and HGT = 7000m is obtained in this scenario embodiment through calculation.

[0135] S208: The HGT drops by more than 3.5 km within 2-3 individual scans. The automatic warning program is started and a warning message is issued.

[0136] For example, the warning message is: A downburst is expected to occur about 20 km to the right of the storm in 12-18 minutes. The actual downburst occurred at 22:15 and about 20 km to the right of the storm center at 21:54.

[0137] According to the above process, by reading the convective cell data in real time and inverting the radar data, potential downbursts can be judged in the storm formation stage, and effective warnings can be issued at least two body scan times, i.e. 12 minutes in advance. The method of the present application can achieve effective warnings of the center location and occurrence time of strong disaster-causing downbursts.

[0138] Therefore, this scenario embodiment can be applied to actual strong disaster-causing downburst prediction scenarios.

[0139] The present application also provides a downburst warning device for implementing the method provided in the present application. Figure 8 , specifically including:

[0140] The monitoring unit 801 is used to obtain the early warning range determined by the radar station and monitor the convective cells that meet the key monitoring conditions that appear within the early warning range.

[0141] A first calculation unit 802, used to collect and calculate characteristic data of the convection cell;

[0142] The first judgment unit 803 is used to judge whether the characteristic data of the convective cell meets the inversion condition when the characteristic data meets the condition for forming a downburst.

[0143] The second calculation unit 804 is used to obtain the three-dimensional wind field data of the convection cell by inverting the characteristic data if the judgment result of the first judgment unit 803 is satisfied, and calculate the horizontal divergence and horizontal vorticity through the three-dimensional wind field data.

[0144] The second judgment unit 805 is used to make a judgment using the horizontal divergence. If a convergence center stronger than the surrounding area appears at the second height, it continues to judge whether there is a convergence center stronger than the surrounding area at the third height, and a divergence center appears in the downwind direction or forward direction of the convergence center.

[0145] The third judgment unit 806 is used to judge whether the convective cell has the preliminary conditions of a strong downburst if the judgment result of the second judgment unit 805 is that the convergence center exists and the divergence center appears.

[0146] The determination unit 807 is used to calculate the moving direction of the storm center and determine the position information of the storm center by using the horizontal vorticity if the determination result of the third determination unit 806 is yes.

[0147] The fourth judgment unit 808 is used to calculate the reflectivity core height and judge whether the reflectivity core height drops by more than a threshold value at least two volume scanning times after the reflectivity core height is higher than the first height.

[0148] The early warning unit 809 is used to start the automatic early warning program and send out an early warning prompt message including the storm center location information if the judgment result of the fourth judgment unit 808 is occurrence.

[0149] In a possible implementation, the key monitoring conditions include:

[0150] The reflectivity intensity of the central area of ​​the convection monomer at the first body scan moment and the second body scan moment exceeds the reflectivity intensity threshold, and the area where the reflectivity intensity of the central area of ​​the convection monomer at the second body scan moment exceeds the reflectivity intensity threshold is larger than the area in the first body scan moment, wherein the first body scan moment and the second body scan moment are continuous.

[0151] In a possible implementation manner, the first computing unit includes:

[0152] The first calculation subunit is used to calculate the high-altitude horizontal wind speed and the vertical shear of the wind speed by using the sounding data within the time threshold.

[0153] The second calculation subunit is used to calculate the high-altitude horizontal wind speed and the vertical shear of the wind speed by using the high-altitude data output by the weather forecast model when the time threshold is exceeded.

[0154] In a possible implementation, the conditions for forming a downburst include:

[0155] The horizontal wind speed at the second height is less than the wind speed threshold, the difference between the horizontal wind speed at the third height and the horizontal wind speed at the second height is less than the first wind speed difference threshold, and the difference between the horizontal wind speed at the third height and the horizontal wind speed at the fourth height is less than the second wind speed difference threshold.

[0156] In a possible implementation, the inversion condition includes:

[0157] The echo top height exceeds the height threshold and the reflectivity intensity in the central area of ​​the convective cell exceeds the reflectivity intensity threshold, and the area where the radar basic reflectivity reaches the basic reflectivity threshold exceeds the area threshold within the interval.

[0158] In a possible implementation manner, the second determining unit includes:

[0159] The first judging subunit is used to judge whether a convergence center stronger than the surrounding area appears at the second height.

[0160] The second judgment subunit is used to judge whether a convergence center stronger than the surrounding area appears at the third height, and whether a divergence center appears in the downwind direction or the forward direction of the convergence center.

[0161] In a possible implementation, the preconditions for the strong downburst include:

[0162] The maximum updraft velocity at the second altitude is at least the first velocity threshold, the updraft velocity at the third altitude is at least the second velocity threshold, the downdraft velocity is at least the first velocity threshold, and the updraft velocity at the first altitude is at least the third velocity threshold, and the downdraft velocity is at least the fourth velocity threshold.

[0163] In a possible implementation manner, the determining unit includes:

[0164] The first determination subunit is used to calculate the moving direction of the storm center according to the horizontal vorticity.

[0165] The second determining subunit is used to determine the location information of the storm center according to the wind speed and the moving direction of the storm center.

[0166] In a possible implementation, the reflectivity core height is determined by:

[0167] The maximum reflectivity is calculated layer by layer from the bottom layer height, and the area corresponding to the difference between the reflectivity of each height being at least the maximum reflectivity and a reflectivity value of at most three is calculated, and the height corresponding to the maximum area is determined as the reflectivity core height.

[0168] The device embodiment of the present application predicts the center position of a convective cell storm and sends a warning message containing the storm center position information, which helps to evacuate people near the storm center in advance and reduce casualties and economic losses.

[0169] The embodiments of the present application also provide corresponding devices and computer storage media for implementing the methods provided in the embodiments of the present application.

[0170] The device includes a memory and a processor, the memory is used to store instructions or codes, and the processor is used to execute the instructions or codes, so that the device executes the downburst warning method described in any embodiment of the present application.

[0171] The computer storage medium stores codes, and when the codes are executed, a device executing the codes implements the downburst warning method described in any embodiment of the present application.

[0172] The "first" and "second" in the names such as "first" and "second" (if any) mentioned in the embodiments of the present application are only used as name identifiers and do not represent the first or second in order.

[0173] Through the description of the above implementation methods, it can be known that those skilled in the art can clearly understand that all or part of the steps in the above-mentioned embodiment method can be implemented by means of software plus a general hardware platform. Based on such an understanding, the technical solution of the present application can be embodied in the form of a software product, which can be stored in a storage medium, such as a read-only memory (ROM) / RAM, a magnetic disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network communication device such as a router) to execute the methods described in each embodiment of the present application or some parts of the embodiments.

[0174] Each embodiment in this specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0175] The above description is merely an exemplary embodiment of the present application and is not intended to limit the protection scope of the present application.

Claims

1. A downburst early warning method, characterized in that: The method comprises: Obtaining the early warning range determined by the radar station and monitoring the convective cells that meet the key monitoring conditions that appear within the early warning range; Collecting and calculating characteristic data of the convection cell; When the characteristic data meets the condition for forming a downburst, determining whether the characteristic data of the convective cell meets the inversion condition; If the conditions are met, the three-dimensional wind field data of the convective cell is obtained by inverting the characteristic data, and the horizontal divergence and horizontal vorticity are calculated by the three-dimensional wind field data; Using the horizontal divergence to judge, if a convergence center stronger than the surrounding area appears at the second height, then continue to judge whether there is a convergence center stronger than the surrounding area at the third height, and a divergence center appears in the downwind direction or forward direction of the convergence center; If there is a convergence center at the third height that is stronger than the surrounding area, and a divergence center appears in the downwind direction or forward direction of the convergence center, then it is determined whether the convective cell has the preliminary conditions for a strong downburst. If so, the horizontal vorticity is used to calculate the moving direction of the storm center and determine the location information of the storm center; Calculate the reflectivity core height and determine whether the reflectivity core height drops by more than a threshold value at least two body scan times after the reflectivity core height is higher than the first height; If it occurs, the automatic warning program is started and a warning message containing the location information of the storm center is issued.

2. The method according to claim 1, characterized in that The key monitoring conditions include: The reflectivity intensity of the central area of ​​the convection monomer at the first body scan moment and the second body scan moment exceeds the reflectivity intensity threshold, and the area where the reflectivity intensity of the central area of ​​the convection monomer at the second body scan moment exceeds the reflectivity intensity threshold is larger than the area in the first body scan moment, wherein the first body scan moment and the second body scan moment are continuous.

3. The method according to claim 1, characterized in that The calculating of the characteristic data of the convection cell comprises: The upper horizontal wind speed and the vertical shear of wind speed are calculated using the sounding data within the time threshold; When the time threshold is exceeded, the high-altitude data output by the weather forecast model are used to calculate the high-altitude horizontal wind speed and the vertical shear of the wind speed.

4. The method according to claim 1, characterized in that: The conditions for forming a downburst include: The horizontal wind speed at the second height is less than the wind speed threshold, the difference between the horizontal wind speed at the third height and the horizontal wind speed at the second height is less than the first wind speed difference threshold, and the difference between the horizontal wind speed at the third height and the horizontal wind speed at the fourth height is less than the second wind speed difference threshold.

5. The method according to claim 1, characterized in that The inversion conditions include: The echo top height exceeds the height threshold and the reflectivity intensity of the central area of ​​the convective cell exceeds the reflectivity intensity threshold, and the area where the radar basic reflectivity reaches the basic reflectivity threshold exceeds the area threshold within the warning range.

6. The method according to claim 1, characterized in that The antecedent conditions of the strong downburst include: The maximum updraft velocity at the second altitude is at least the first velocity threshold, the updraft velocity at the third altitude is at least the second velocity threshold, the downdraft velocity is at least the first velocity threshold, and the updraft velocity at the first altitude is at least the third velocity threshold, and the downdraft velocity is at least the fourth velocity threshold.

7. The method according to claim 1, characterized in that The reflectivity core height is obtained by the following steps: The maximum reflectivity is calculated layer by layer from the bottom layer height, and the area corresponding to the difference between the reflectivity of each height being at least the maximum reflectivity and a reflectivity value of at most three is calculated, and the height corresponding to the maximum area is determined as the reflectivity core height.

8. The method according to claim 1, characterized in that The warning message also includes: The occurrence time information of the strong disaster-causing downburst.

9. A downburst warning device, characterized in that: The device comprises: A monitoring unit, used to obtain the early warning range determined by the radar station and monitor the convective cells that meet the key monitoring conditions that appear within the early warning range; A first calculation unit, used for collecting and calculating characteristic data of the convection cell; A first judgment unit, configured to judge whether the characteristic data of the convective cell meets an inversion condition when the characteristic data meets a condition for forming a downburst; A second calculation unit is configured to, if the judgment result of the first judgment unit is satisfied, invert the three-dimensional wind field data of the convection cell using the characteristic data, and calculate the horizontal divergence and the horizontal vorticity through the three-dimensional wind field data; A second judgment unit is used to judge by using the horizontal divergence, and if a convergence center stronger than the surrounding area appears at the second height, continue to judge whether there is still a convergence center stronger than the surrounding area at the third height, and a divergence center appears in the downwind direction or forward direction of the convergence center; A third judgment unit is used to judge whether the convective cell has the preliminary conditions of a strong downburst if the judgment result of the second judgment unit is that the convergence center exists and the divergence center appears; a determination unit, configured to calculate the moving direction of the storm center and determine the position information of the storm center by using the horizontal vorticity if the determination result of the third determination unit is satisfied; A fourth judgment unit, configured to calculate a reflectivity core height and judge whether the reflectivity core height decreases by more than a threshold value at least two body scan times after the reflectivity core height is higher than the first height; The early warning unit is used to start the automatic early warning program and send out an early warning prompt message containing the storm center location information if the judgment result of the fourth judgment unit is that the storm has occurred.

10. A downburst warning device, characterized in that: The device comprises: A memory, used for storing the downburst warning program or code; A processor is used to execute the downburst warning program or code to implement the downburst warning method according to any one of claims 1 to 8.

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