A method for calculating atmospheric water vapor content based on E-band microwave communication link

Abstract

A method for calculating atmospheric water vapor content based on an E-band microwave communication link, comprising: S1, selecting a monitoring target area, and constructing an E-band microwave communication link in the monitoring target area; S2, collecting sample data according to a preset sample period, the sample data including a received signal level value and a water vapor attenuation value of the E-band microwave communication link; S3, calculating a received signal level reference value based on a median value of the received signal level value and a median value of the water vapor attenuation value in the sample data; S4, calculating a value range of the received signal level value based on a limit value of the received signal level value and a maximum value of the water vapor attenuation value in the sample data; S5, collecting real-time data of the received signal level value of the E-band microwave communication link, and optimizing the real-time data using the value range; S6, inverting the real-time data to obtain the atmospheric water vapor content. The present invention improves the method for extracting water vapor attenuation values, improves the time resolution of inverted water vapor density, and reduces estimation errors.

Description

Technical Field

[0001] The present invention relates to the technical field of meteorological observation, and in particular to a method for calculating atmospheric water vapor content based on an E-band microwave communication link. Background Art

[0002] The water vapor content in the atmosphere varies greatly and plays a major role in weather changes. Since the atmospheric temperature is much lower than the boiling point of the water surface, water vapor can undergo a phase change effect in the atmosphere. The evaporation and condensation of water vapor can absorb and release latent heat, which directly affects the temperature of the ground and the air. Therefore, it plays an important role in the vertical stability of the atmosphere and the structure and evolution of convective storm systems. The direction and intensity of water vapor diffusion and transport directly affect the regional water cycle system. For inland areas where the surface is short of water and the horizontal water exchange process on the ground is relatively weak, water vapor diffusion and transport are of particular significance to the regional water cycle process. Many weather changes and natural disasters are closely related to water vapor. It is an important physical quantity for predicting rainfall, mesoscale severe weather and global climate change. Therefore, the study and detection of water vapor is very important, which is conducive to improving the accuracy of numerical weather forecast models.

[0003] The ideal requirements for water vapor detection models are high temporal and spatial resolution, wide coverage, and accurate measurement. At present, the commonly used ground stations, radiosondes, and satellite systems cannot fully meet these requirements. The measurement of humidity at ground stations is the most direct means to reflect water vapor, but because it provides point observations, it cannot meet the requirements of high spatial resolution. The radiosonde method is the most important way to obtain vertical distribution data of humidity. Its data has high accuracy and resolution. Due to the limitation of equipment cost, radiosondes are only launched twice a day and cannot accurately monitor the temporal and spatial changes of water vapor. The coverage of satellite systems is much larger than that of general monitoring systems, but there are still limitations in accurately measuring near-ground humidity. Near-ground humidity is usually a key variable for convection. Therefore, it is necessary to develop a near-ground high-quality water vapor density measurement technology.

[0004] Studies have shown that millimeter waves are affected by atmospheric factors during propagation, which can cause signal attenuation. The E-band range includes 71-76 GHz and 81-86 GHz. Because of the high frequency and short wavelength, it is more susceptible to interference from water vapor in the atmosphere. Based on this characteristic, Messe et al. first proposed a method for monitoring near-ground rainfall and retrieving rainfall data using a communication link. Since then, many studies have demonstrated the feasibility of this method for estimating rainfall. The existing methods of using millimeter waves to measure water vapor content generally have the problem of a serious reduction in the accuracy of the results due to various random errors, and the complexity is high. Summary of the invention

[0005] In order to address the deficiencies in the prior art, the present invention provides a method for calculating atmospheric water vapor content based on an E-band microwave communication link, improves the method for extracting water vapor attenuation values, increases the temporal resolution of inverted water vapor density, reduces estimation errors, and is beneficial to the accuracy of disastrous weather prediction.

[0006] In order to achieve the above object, the specific scheme adopted by the present invention is: a method for calculating atmospheric water vapor content based on an E-band microwave communication link, the method comprising the following steps:

[0007] S1. Select a monitoring target area and build an E-band microwave communication link in the monitoring target area;

[0008] S2. Collecting sample data according to a preset sample period, the sample data including a received signal level value and a water vapor attenuation value of an E-band microwave communication link;

[0009] S3, calculating a received signal level reference value based on a median value of the received signal level value and a median value of the water vapor attenuation value in the sample data;

[0010] S4, calculating the value range of the received signal level value based on the limit value of the received signal level value and the maximum value of the water vapor attenuation value in the sample data;

[0011] S5, collecting real-time data of the level value of the received signal of the E-band microwave communication link, and optimizing the real-time data using the value range;

[0012] S6. Invert the real-time data to obtain the atmospheric water vapor content.

[0013] As a further optimization of the above-mentioned atmospheric water vapor content calculation method based on the E-band microwave communication link: the E-band microwave communication link is a bidirectional link, and the signal frequency of the E-band microwave communication link is 73 GHz and / or 83 GHz.

[0014] As a further optimization of the above-mentioned atmospheric water vapor content calculation method based on the E-band microwave communication link: in S2, after the received signal level value is collected, a sliding average processing is performed on it.

[0015] As a further optimization of the above-mentioned atmospheric water vapor content calculation method based on the E-band microwave communication link: in S3, the calculation method of the received signal level reference value is: RSL med is the median value of the received signal level, is the median water vapor attenuation value.

[0016] As a further optimization of the above-mentioned atmospheric water vapor content calculation method based on the E-band microwave communication link: In S4, the value range of the received signal level value is

[0017] [RSL low ,RSL up ], Among them A vmin is the minimum value of water vapor attenuation, A vmax is the maximum value of water vapor attenuation.

[0018] As a further optimization of the above-mentioned atmospheric water vapor content calculation method based on the E-band microwave communication link: In S5, the method for optimizing the real-time data is:

[0019] RSL i For real-time data.

[0020] As a further optimization of the above-mentioned atmospheric water vapor content calculation method based on the E-band microwave communication link: the specific method of S6 is:

[0021] S61, calculating water vapor attenuation analysis data using real-time data and a received signal level reference value;

[0022] S62. Calculate the characteristic attenuation of the E-band microwave communication link based on the water vapor attenuation analysis data;

[0023] S63. Invert atmospheric water vapor content based on characteristic attenuation of E-band microwave communication link.

[0024] As a further optimization of the above-mentioned atmospheric water vapor content calculation method based on the E-band microwave communication link: In S61, the method for calculating the water vapor attenuation analysis data is:

[0025] In S62, the method for calculating the characteristic attenuation of the E-band microwave communication link is: Where l is the link length of the E-band microwave communication link.

[0026] Beneficial effects: The present invention improves the method for extracting water vapor attenuation values, increases the temporal resolution of inverted water vapor density, reduces estimation errors, and is beneficial to the accuracy of disastrous weather prediction. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] See also Figure 1 , a method for calculating atmospheric water vapor content based on an E-band microwave communication link, the method including S1 to S6.

[0030] S1. Select a monitoring target area and construct an E-band microwave communication link in the monitoring target area. The E-band microwave communication link is a bidirectional link, and the signal frequency of the E-band microwave communication link is 73 GHz and / or 83 GHz. More specifically, the polarization mode of the E-band microwave communication link is vertical polarization, the transmission power is 7 dBm, the receiving end and the transmitting end are sampled once every 1 minute, and the quantization resolution is 1 dB.

[0031] S2. Sample data is collected according to a preset sample period. The sample data includes the received signal level value and water vapor attenuation value of the E-band microwave communication link. In S2, after the received signal level value is collected, a sliding average process is performed on it. Through the sliding average process, the random errors of frequent fluctuations are filtered out, thereby ensuring the accuracy of the final result. The specific method of sliding average processing can be expressed as:

[0032]

[0033] Wherein, N is the time length, and m is the number of received signal level values.

[0034] S3. Calculate a received signal level reference value based on the median of the received signal level value and the median of the water vapor attenuation value in the sample data. In S3, the received signal level reference value is calculated as follows: RSL med is the median value of the received signal level, The reference value is actually the received signal level value when the water vapor attenuation value is 0 in the sample data. In order to ensure the accuracy of the reference value, the median of the received signal level value and the median of the water vapor attenuation value are used for calculation in this embodiment.

[0035] S4. Calculate the value range of the received signal level value based on the limit value of the received signal level value and the maximum value of the water vapor attenuation value in the sample data. In S4, the value range of the received signal level value is

[0036] [RSL low ,RSL up ], Among them A vmin is the minimum value of water vapor attenuation, A vmax is the maximum value of water vapor attenuation.

[0037] The value range of the received signal level value calculated based on the reference value is essentially a reasonable range of the received signal level value. The received signal level value can be optimized through the value range to exclude abnormal values ​​caused by factors such as strong winds or equipment failures that affect the E-band microwave communication link, thereby ensuring the accuracy of the final result.

[0038] S5, collecting real-time data of the level value of the received signal of the E-band microwave communication link, and optimizing the real-time data using the value range. In S5, the method for optimizing the real-time data is:

[0039] RSL i For real-time data.

[0040] By optimizing real-time data, abnormal real-time data can be optimized to a reasonable range, thereby avoiding interference of abnormal data on the final calculation results and improving the accuracy of the results.

[0041] S6. Invert the real-time data to obtain the atmospheric water vapor content. The specific method of S6 is S61 to S63.

[0042] S61, using the real-time data and the received signal level reference value to calculate water vapor attenuation analysis data. In S61, the method for calculating the water vapor attenuation analysis data is:

[0043] S62: Calculate the characteristic attenuation of the E-band microwave communication link based on the water vapor attenuation analysis data. In S62, the method for calculating the characteristic attenuation of the E-band microwave communication link is: Where l is the link length of the E-band microwave communication link.

[0044] S63. Invert atmospheric water vapor content based on characteristic attenuation of E-band microwave communication link. In this embodiment, the atmospheric water vapor content is inverted using the method recommended by ITU-R No. 676-10, which belongs to the prior art in this field and will not be described in detail here.

[0045] In order to verify the effect of the present invention, the present invention is based on the observation test results of the Xianghe Atmosphere Comprehensive Observation Experiment Station of the Institute of Atmospheric Physics, Chinese Academy of Sciences, and the transmitting end of the E-band microwave communication link is set at the experimental station, and the link length l is set to 4.8Km. The test is carried out continuously for one year, and the effect is evaluated by the Pearson correlation coefficient PCC, the root mean square error RMSE and the mean relative error MRE. The calculation methods of the three parameters are as follows:

[0046]

[0047]

[0048]

[0049] When k is 1, X i,1 represents the estimated water vapor density when the link operates at 73 GHz. When k is 2, X i,2 represents the estimated water vapor density when the link operates at 83 GHz. X and σ X X i,k The mean and standard deviation of Y i represents the water vapor density measured by the weather station, μ Y and σ Y Y i The closer the correlation coefficient is to 1, the smaller the mean square error and the average relative error are, which means that there is a better similarity between the two data sets, indicating that the results of the present invention are more accurate. The specific results are shown in Table 1.

[0050] Table 1 Comparison table of correlation, root mean square error, mean relative error and mean values ​​of each quarter between the calculation results of the present invention and the observation values ​​of the test station

[0051]

[0052]

[0053] As can be seen from Table 1, the correlation in June is the highest and the root mean square error and average relative error are also low, which can determine that the calculation effect in June is the best. In terms of seasons, in summer and when the link works at 83 GHz, the correlation is the highest and the average relative error is the lowest. Similarly, the evaluation results in June at 83 GHz are better, which shows that the effect of using the 83 GHz E-band microwave communication link is better.

[0054] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for calculating atmospheric water vapor content based on an E-band microwave communication link, characterized in that: The method comprises the following steps: S1. Select a monitoring target area and build an E-band microwave communication link in the monitoring target area; S2. Collecting sample data according to a preset sample period, the sample data including a received signal level value and a water vapor attenuation value of an E-band microwave communication link; S3, based on the median of the received signal level value and the median of the water vapor attenuation value in the sample data, the received signal level reference value is calculated; in S3, the calculation method of the received signal level reference value is: RSL ref =RSL med +A vmed , where RSL med is the median value of the received signal level, A vmed is the median water vapor attenuation value; S4, based on the limit value of the received signal level value and the maximum value of the water vapor attenuation value in the sample data, the value range of the received signal level value is calculated; in S4, the value range of the received signal level value is Among them A vmin is the minimum value of water vapor attenuation, A vmax is the maximum value of water vapor attenuation; S5, collecting real-time data of the level value of the received signal of the E-band microwave communication link, and optimizing the real-time data using the value range; in S5, the method for optimizing the real-time data is: S6. Invert the real-time data to obtain the atmospheric water vapor content. The specific method of S6 is: S61, calculating water vapor attenuation analysis data using real-time data and a received signal level reference value; S62. Calculate the characteristic attenuation of the E-band microwave communication link based on the water vapor attenuation analysis data; S63. Invert atmospheric water vapor content based on characteristic attenuation of E-band microwave communication link.

2. The method for calculating atmospheric water vapor content based on an E-band microwave communication link according to claim 1, characterized in that: The E-band microwave communication link is a bidirectional link, and the signal frequency of the E-band microwave communication link is 73 GHz and / or 83 GHz.

3. The method for calculating atmospheric water vapor content based on an E-band microwave communication link according to claim 1, characterized in that: In S2, the received signal level values ​​are collected and then subjected to sliding average processing.

4. The method for calculating atmospheric water vapor content based on an E-band microwave communication link according to claim 1, characterized in that: In S61, the method for calculating water vapor attenuation analysis data is A vi =-RSL i +RSL ref ; In S62, the method for calculating the characteristic attenuation of the E-band microwave communication link is: Where l is the link length of the E-band microwave communication link.

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