Cloud cover calculation method and device based on millimeter wave ceilometer

Abstract

The invention relates to a cloud cover calculation method and device based on a millimeter wave ceilometer, and belongs to the field of radio, the calculation method comprises the following steps: circularly inputting radar data, reading latest radar base data, and removing clutters according to a reflectivity threshold; segmenting different cloud layers according to the continuity of the reflectivity, and respectively calculating the cloud bottom height, the cloud layer thickness and the reflectivity weighted value of each layer of cloud in the radial direction; cloud cover calculation and each radial cloud cover calculation are carried out through the cloud base height, the cloud layer thickness and the reflectivity weighted value; and the cloud amount at the current moment is obtained according to the time corresponding to each radial direction multiplied by different weights, then a result is output, the accumulated cloud amount is sent to a cycle, and real-time cloud amount data is continuously obtained. According to the method, the reliability of data is improved, and a good foundation is laid for subsequent data observation and processing. Accurate calculation of the cloud cover helps to improve the accuracy of weather forecast.

Description

Technical Field

[0001] The present invention relates to the field of radio, and in particular to a cloud amount calculation method and device based on a millimeter wave cloud detector. Background Art

[0002] Cloud amount refers to the percentage of the sky view obscured by clouds, and is one of the important indicators characterizing weather and climate characteristics. It reflects the process of water vapor condensation and cloud formation in the atmosphere, and has a direct impact on weather phenomena such as atmospheric radiation, temperature change, and precipitation. The millimeter wave cloud detector can clearly describe the internal physical structure of clouds with high temporal and spatial resolution, strong penetration ability, and continuous monitoring ability, and has become an important tool in meteorological research and cloud physics observation. However, the field of view of the millimeter wave cloud detector is small, and the measurement accuracy is low only by the cloud detector. Therefore, how to calculate the cloud amount through the millimeter wave cloud detector is a problem that needs to be considered currently. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art, and provides a cloud amount calculation method and device based on a millimeter wave cloud detector, which solves the deficiencies existing in the prior art.

[0004] The purpose of the present invention is achieved through the following technical solutions: A cloud amount calculation method based on a millimeter wave cloud detector, the calculation method includes: S1. Circularly input radar data, read the latest radar base data, and remove clutter according to the reflectivity threshold; S2. Segment different cloud layers according to the continuity of reflectivity, and respectively calculate the cloud base height, cloud layer thickness, and reflectivity weighted value of each layer of cloud in the radial direction; S3. Perform cloud amount calculation and calculate the cloud amount of each radial cloud through the cloud base height, cloud layer thickness, and reflectivity weighted value; S4. Multiply the time corresponding to each radial direction by different weights to obtain the cloud amount at the current moment and output the result, and send the cumulative cloud amount into the loop to continuously obtain real-time cloud amount data.

[0005] The S2 includes: In the radial direction, if there is a region where the reflectivity has values in more than N range bins, and the proportion of the range bins with reflectivity values in this region exceeds the set value, then this region with continuous reflectivity values is a layer of cloud, and there are at least N range bins with no values between cloud layers; After cloud layer segmentation, calculate the cloud base height, cloud layer thickness, and reflectivity weighted value of each layer respectively. Among them, the cloud base height is the number of the first range bin with reflectivity value of this layer of cloud multiplied by the range resolution, the cloud layer thickness is the number of range bins occupied from the first range bin with reflectivity value to the last range bin with reflectivity value of this layer of cloud multiplied by the range resolution, and the reflectivity weighted value is the sum of the average reflectivity of this layer of cloud and the reflectivity threshold divided by 15.

[0006] The cloud amount calculation in S3 includes: According to the different cloud base heights, different coefficients are used to calculate the cloud amount. If the cloud base height is less than 0.5 km and the cloud layer thickness exceeds 0.6 km, it is considered that rain is about to fall or is falling, and it is in a full cloud state, and the cloud amount is the maximum value; In other cases, the cloud amount is equal to the coefficient multiplied by the cloud layer thickness multiplied by the reflectivity weighting value. If the cloud base height is less than 2.5 km, this layer is considered a low cloud, and the coefficient is 40. If the cloud base height is greater than 2.5 km and less than 8.5 km, this layer of cloud is considered a middle cloud, and the coefficient is 35. If the cloud base height is greater than 8.5 km, this layer of cloud is considered a high cloud, and the coefficient is 25.

[0007] The calculation of the cloud amount in each radial direction in S3 includes: According to the sum of the cloud amounts of each layer in the obtained radial direction, the cloud amount in the radial direction is obtained. The maximum value of the cloud amount in each radial direction is set to 150. If the cloud amount in the last radial direction is greater than 100, the part exceeding 100 is accumulated into the cloud amount cumulative value. If the cloud amount in the last radial direction is less than 100 and the cloud amount cumulative value is greater than 0, the cloud amount cumulative value is used to fill the last radial direction, with a maximum filling of 100. If the cloud amount in the last radial direction is less than 100 and the cloud amount cumulative value is less than 0, no processing is performed.

[0008] A cloud amount calculation device based on a millimeter wave cloud detector, the device includes a data preprocessing module, a cloud layer segmentation and calculation module, a cloud amount calculation module, and a real-time cloud amount acquisition module; The data preprocessing module is configured to cyclically input radar data, read the latest radar base data, and remove clutter according to the reflectivity threshold; The cloud layer segmentation and calculation module is configured to segment different cloud layers according to the continuity of the reflectivity, and respectively calculate the cloud base height, cloud layer thickness, and reflectivity weighting value of the clouds in each layer in the radial direction; The cloud amount calculation module is configured to perform cloud amount calculation and calculation of the cloud amount in each radial direction through the cloud base height, cloud layer thickness, and reflectivity weighting value; The real-time cloud amount acquisition module is configured to obtain the cloud amount at the current moment by multiplying the time corresponding to each radial direction by different weights and then output the result, and send the cumulative cloud amount into the cycle to continuously obtain real-time cloud amount data.

[0009] The cloud layer segmentation and calculation module specifically includes the following: In the radial direction, if there are more than N distance bins with non-zero reflectivity values, and the proportion of the distance bins with non-zero reflectivity values in this area exceeds the set value, then this area with continuous non-zero reflectivity values is a cloud layer, and there are at least N distance bins with zero values between cloud layers; After cloud layer segmentation, calculate the cloud base height, cloud layer thickness, and reflectivity weighted value of each layer respectively. Among them, the cloud base height is the number of range bins with a valid reflectivity in the first layer of cloud multiplied by the range resolution. The cloud layer thickness is the number of range bins occupied between the first range bin with a valid reflectivity and the last range bin with a valid reflectivity in this layer of cloud multiplied by the range resolution. The reflectivity weighted value is the sum of the average reflectivity of this layer of cloud and the reflectivity threshold divided by 15.

[0010] The cloud amount calculation in the cloud amount calculation module includes: According to different cloud base heights, use different coefficients to calculate the cloud amount. If the cloud base height is less than 0.5 km and the cloud layer thickness exceeds 0.6 km, it is considered that rain is about to fall or is falling, and it is in a full cloud state, and the cloud amount is the maximum value; In other cases, the cloud amount is equal to the coefficient multiplied by the cloud layer thickness multiplied by the reflectivity weighted value. If the cloud base height is less than 2.5 km, it is considered that this layer is a low cloud, and the coefficient is 40. If the cloud base height is greater than 2.5 km and less than 8.5 km, it is considered that this layer of cloud is a middle cloud, and the coefficient is 35. If the cloud base height is greater than 8.5 km, it is considered that this layer of cloud is a high cloud, and the coefficient is 25.

[0011] The calculation of the cloud amount in each radial direction in the cloud amount calculation module includes: According to the sum of the cloud amounts of each layer in the obtained radial direction, obtain the cloud amount in the radial direction. Set the maximum value of the cloud amount in each radial direction to 150. If the cloud amount in the last radial direction is greater than 100, accumulate the part exceeding 100 into the cloud amount accumulation value. If the cloud amount in the last radial direction is less than 100 and the cloud amount accumulation value is greater than 0, fill the last radial direction with the cloud amount accumulation value, and the maximum filling is 100. If the cloud amount in the last radial direction is less than 100 and the cloud amount accumulation value is less than 0, no processing is performed.

[0012] The present invention has the following advantages: A cloud amount calculation method and device based on a millimeter wave cloud detector can estimate the cloud coverage rate of the entire sky at the current moment through the cloud base height, cloud layer thickness, reflectivity intensity, etc. within a certain period of time. It can calculate the cloud amount well on the basis of removing clutter, improve the reliability of data, and lay a good foundation for the subsequent observation and processing of data. Accurately calculating the cloud amount helps to improve the accuracy of weather forecasting. Brief Description of the Drawings

[0013] Figure 1 It is a flow schematic diagram of the present invention; Figure 2 It is an effect schematic diagram of the present invention. Detailed Embodiment

[0014] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part rather than all of the embodiments of this application. Components of the embodiments of this application usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of this application provided below with reference to the accompanying drawings is not intended to limit the protection scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative efforts belong to the protection scope of this application. The present invention will be further described below with reference to the accompanying drawings.

[0015] As Figure 1 shown, the present invention specifically relates to a cloud amount calculation method based on a millimeter-wave cloud detector. First, data preprocessing is performed, the radar data is cyclically input, and the latest radar base data is read. Then, clutter is removed according to the reflectivity threshold. Then, different cloud layers are segmented according to the continuity of the reflectivity. Then, the cloud base height, cloud layer thickness, and reflectivity weighted value of each layer of cloud in the radial direction are calculated respectively. Then, the cloud amount of each layer of cloud in the radial direction and the cloud amount in the radial direction are calculated through the cloud base height, cloud layer thickness, and reflectivity weighted value. Finally, the cloud amount at the current moment is obtained by multiplying the time corresponding to each radial direction by different weights, the result is output, and the cumulative cloud amount is sent into the loop to continuously obtain real-time cloud amount data.

[0016] Further, the data preprocessing includes: inputting the radar data, setting the cloud amount cumulative value cc_cum to 0, reading the latest radar base data. In the present invention, the latest 30-minute data is selected to obtain the basic reflectivity. A suitable threshold mm is selected to remove the clutter with lower reflectivity and reduce the misguidance to the subsequent cloud amount calculation.

[0017] The cloud layer segmentation includes: in the radial direction, if there is an area where the reflectivity has values in more than 10 range bins, and the proportion of the range bins with non-zero reflectivity in this area exceeds 70%, then this area with continuous non-zero reflectivity is considered as one layer of cloud, and there are at least 10 range bins with no values between cloud layers. After cloud layer segmentation, information such as the cloud base height, cloud layer thickness, and reflectivity weighted value of each layer is calculated respectively. Among them, the cloud base height is the number of the first range bin with non-zero reflectivity of this layer of cloud multiplied by the range resolution, the cloud layer thickness is the number of range bins occupied between the first range bin with non-zero reflectivity and the last range bin with non-zero reflectivity of this layer of cloud multiplied by the range resolution, and the reflectivity weighted value is the sum of the average reflectivity of this layer of cloud and mm divided by 15.

[0018] Cloud amount calculation includes: different coefficients are used to calculate the cloud amount according to different cloud base heights; when the cloud base height is extremely low <0.5 km and the cloud layer thickness exceeds 0.6 km, it is considered that rain is about to fall or is falling, and it is in a full cloud state with the cloud amount being the maximum value; in other cases, cloud amount = coefficient × cloud layer thickness × reflectivity weighting value. If the cloud base height is less than 2.5 km, the cloud layer is considered a low cloud with a coefficient of 40; if the cloud base height is greater than 2.5 km and less than 8.5 km, the cloud layer is considered a middle cloud with a coefficient of 35; if the cloud base height is greater than 8.5 km, the cloud layer is considered a high cloud with a coefficient of 25.

[0019] The calculation of cloud amount in each radial direction includes: obtaining the cloud amount in the radial direction based on the sum of cloud amounts of each layer in the obtained radial direction. To better simulate the process of the cloud layer slowly dissipating after rainfall, the maximum cloud amount of each radial direction is set to 150. If the cloud amount of the last radial direction is greater than 100, the part exceeding 100 is accumulated into cc_cum; if the cloud amount of the last radial direction is less than 100 and cc_cum > 0, then cc_cum is used to fill the last radial direction, with the maximum filling up to 100; if the cloud amount of the last radial direction is less than 100 and cc_cum < 0, no processing is performed.

[0020] Time weighting includes: different weights are assigned according to the different time distances of the corresponding time of cloud amounts in each radial direction from the current moment. The time weight of the first 2 / 3 is 1, and the time weight of the last 1 / 3 is 2. Since the maximum cloud amount set in the present invention is 150 and the maximum value is 100 when outputting the result, if the finally calculated result is greater than 100, it is changed to 100 for output. And cc_cum is sent to the data reading place to prepare for the calculation of the cloud amount at the next moment.

[0021] As Figure 2 shown, it is the cloud amount calculation effect of the millimeter-wave cloud detector. The left side is the reflectivity color scale, the right side is the cloud amount value. The broken line with "★" is the cloud amount of the all-sky imager, the broken line with "○" is the cloud amount calculated by the present invention, and the rest are radar reflectivity values. From Figure 2 it can be seen that the change degrees of the two lines are very similar. The Pearson correlation coefficient is used to measure the correlation between the cloud amount calculated by the present invention and the cloud amount of the all-sky imager. The result representation range is [-1, 1]. Greater than 0 indicates a positive correlation between the two, less than 0 indicates a negative correlation, and the greater the absolute value, the higher the correlation degree and the more reliable the present invention. During this rainfall process, the correlation coefficient between the two reaches 0.96, indicating that the present invention has a good effect.

[0022] The above are only the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications, and improvements, and can be changed within the scope of the concept described herein through the above teachings or the technology or knowledge in the relevant field. And any changes and modifications made by those skilled in the art without departing from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. A cloud amount calculation method based on millimeter wave cloud meter, characterized in that: The calculation method includes: S1, loop input radar data, read the latest radar base data, and remove clutter according to the reflectivity threshold; S2, segment different cloud layers according to the continuity of reflectivity, and calculate the cloud base height, cloud thickness and reflectivity weighted value of each cloud layer in the radial direction respectively; S3, calculate the cloud amount and the radial cloud amount by cloud base height, cloud thickness and reflectivity weighted value; S4. Multiply the time corresponding to each radial direction by different weights to obtain the cloud cover at the current moment and then output the result. Send the accumulated cloud cover into the loop to continuously obtain real-time cloud cover data.

2. The cloud amount calculation method based on millimeter wave cloud meter according to claim 1 is characterized in that: The S2 includes: In the radial direction, if there are more than N distance bins with reflectivity values, and the proportion of distance bins with reflectivity values ​​in this area exceeds the set value, then this section of the reflectivity connection with a value is a layer of cloud, and there are at least N distance bins without values ​​between the cloud layers; After cloud segmentation, the cloud base height, cloud thickness and reflectivity weighted value of each layer are calculated respectively. The cloud base height is the number of distance bins with the first reflectivity value of the cloud layer multiplied by the distance resolution, the cloud thickness is the number of distance bins occupied from the first distance bin with reflectivity value to the last distance bin with reflectivity value of the cloud layer multiplied by the distance resolution, and the reflectivity weighted value is the sum of the mean reflectivity of the cloud layer plus the reflectivity threshold divided by 15.

3. The cloud amount calculation method based on millimeter wave cloud meter according to claim 2 is characterized in that: The cloud volume calculation in S3 includes: Different coefficients are used to calculate cloud cover according to the different cloud base heights. If the cloud base height is less than 0.5 km and the cloud thickness exceeds 0.6 km, it is considered that it is about to rain or is raining, which is a full cloud state and the cloud cover is at its maximum value. In other cases, the cloud amount is equal to the coefficient multiplied by the cloud thickness multiplied by the reflectivity weighted value. If the cloud base height is less than 2.5km, the cloud layer is considered to be low cloud with a coefficient of 40. If the cloud base height is greater than 2.5km and less than 8.5km, the cloud layer is considered to be medium cloud with a coefficient of 35. If the cloud base height is greater than 8.5km, the cloud layer is considered to be high cloud with a coefficient of 25.

4. The cloud amount calculation method based on millimeter wave cloud meter according to claim 2 is characterized in that: The calculation of each radial cloud amount in S3 includes: The cloud amount in the radial direction is obtained according to the sum of the cloud amounts of each layer in the radial direction, and the maximum cloud amount in each radial direction is set to 150. If the cloud amount in the last radial direction is greater than 100, the part exceeding 100 will be accumulated in the cloud amount accumulation value. If the cloud amount in the last radial direction is less than 100 and the cloud amount accumulation value is greater than 0, the cloud amount accumulation value will be used to fill the last radial direction, up to a maximum of 100. If the cloud amount in the last radial direction is less than 100 and the cloud amount accumulation value is less than 0, no processing will be performed.

5. A cloud amount calculation device based on a millimeter wave cloud meter, characterized in that: The device includes a data preprocessing module, a cloud layer segmentation and calculation module, a cloud amount calculation module and a real-time cloud amount acquisition module; The data preprocessing module is configured to cyclically input radar data, read the latest radar base data, and remove clutter according to a reflectivity threshold; The cloud layer segmentation and calculation module is configured to segment different cloud layers according to the continuity of reflectivity, and respectively calculate the cloud base height, cloud layer thickness and reflectivity weighted value of each cloud layer in the radial direction; The cloud amount calculation module is configured to calculate the cloud amount and the cloud amount in each radial direction through the cloud base height, cloud thickness and reflectivity weighted value; The real-time cloud amount acquisition module is configured to output the result after obtaining the cloud amount at the current moment by multiplying the time corresponding to each radial direction by different weights, and to send the accumulated cloud amount into a loop to continuously obtain real-time cloud amount data.

6. The cloud amount calculation device based on millimeter wave cloud meter according to claim 5, characterized in that: The cloud layer segmentation and calculation module specifically includes the following contents: In the radial direction, if there are more than N distance bins with reflectivity values, and the proportion of distance bins with reflectivity values ​​in this area exceeds the set value, then this section of the reflectivity connection with a value is a layer of cloud, and there are at least N distance bins without values ​​between the cloud layers; After cloud segmentation, the cloud base height, cloud thickness and reflectivity weighted value of each layer are calculated respectively. The cloud base height is the number of distance bins with the first reflectivity value of this cloud layer multiplied by the distance resolution, the cloud thickness is the number of distance bins occupied from the first distance bin with reflectivity value to the last distance bin with reflectivity value of this cloud layer multiplied by the distance resolution, and the reflectivity weighted value is the sum of the mean reflectivity of this cloud layer plus the reflectivity threshold divided by 15.

7. The cloud amount calculation device based on millimeter wave cloud meter according to claim 6, characterized in that: The cloud amount calculation in the cloud amount calculation module includes: Different coefficients are used to calculate cloud cover according to the different cloud base heights. If the cloud base height is less than 0.5 km and the cloud thickness exceeds 0.6 km, it is considered that it is about to rain or is raining, which is a full cloud state and the cloud cover is at its maximum value. In other cases, the cloud amount is equal to the coefficient multiplied by the cloud thickness multiplied by the reflectivity weighted value. If the cloud base height is less than 2.5km, the layer is considered to be low cloud with a coefficient of 40. If the cloud base height is greater than 2.5km and less than 8.5km, the cloud layer is considered to be medium cloud with a coefficient of 35. If the cloud base height is greater than 8.5km, the cloud layer is considered to be high cloud with a coefficient of 25.

8. The cloud amount calculation device based on millimeter wave cloud meter according to claim 6, characterized in that: Each radial cloud amount calculation in the cloud amount calculation module includes: The cloud amount in the radial direction is obtained according to the sum of the cloud amounts of each layer in the radial direction, and the maximum cloud amount in each radial direction is set to 150. If the cloud amount in the last radial direction is greater than 100, the part exceeding 100 will be accumulated in the cloud amount accumulation value. If the cloud amount in the last radial direction is less than 100 and the cloud amount accumulation value is greater than 0, the cloud amount accumulation value will be used to fill the last radial direction, up to a maximum of 100. If the cloud amount in the last radial direction is less than 100 and the cloud amount accumulation value is less than 0, no processing will be performed.

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