CN104819963A - Measurement method and monitoring system of atmosphere vertical visibility - Google Patents

Abstract

The invention discloses a measuring method and a monitoring system for atmospheric vertical visibility. The measuring method of the present invention utilizes the laser ceilometer and the visibility meter to establish a new relationship between the extinction coefficient and the visibility, overcomes the influence of the difference in the relationship between the extinction coefficient and the visibility on the vertical visibility caused by the different microphysical characteristics of the atmospheric aerosol particles, and obtains a more accurate Atmospheric vertical visibility and can be used in various environments. The monitoring system of the invention can monitor the vertical visibility in real time and around the clock without unattended observation.

Description

A measurement method and monitoring system for atmospheric vertical visibility

technical field

The present invention relates to a measurement method and a monitoring system of atmospheric vertical visibility.

Background technique

Visibility is an important element of meteorological observation. With the development of world science and technology and economy, aerospace, sea and land transportation, environmental monitoring and defense departments have higher and higher requirements for accurate visibility forecasting. Therefore, the development and application of visibility measuring instruments are more important. Since Koschmieder established the basic theory of visibility measurement in 1924, many experts at home and abroad have devoted themselves to the development of visibility measurement instruments. Over the past few decades, both in theory and in practice, visibility measurement instruments and theories have become increasingly mature. With the popularity of computers and the promotion of integrated circuits, visibility measuring instruments are constantly being updated, and the application market has expanded from a small amount of use in airports instead of subjective visual inspection in the 1950s to a large number of equipment in various airports, ports, bridges, highways, etc. Railways, environmental protection, meteorological stations, forestry and defense departments.

Vertical visibility refers to the maximum distance at which the target can be seen vertically upwards with the naked eye on the ground when the sky is foggy, floating dust, low clouds or precipitation. Atmospheric vertical visibility can not only reflect the stability of the atmosphere, but also serve as an important factor for judging the nature of air masses and studying air pollution. In addition, the visibility in the vertical direction of the atmosphere also provides security for aircraft takeoff and landing and people's daily life, especially has an important impact on the Air Defense Security Bureau, and has attracted more and more attention. Therefore, it is of great significance to conduct detection research on atmospheric vertical visibility. At present, there are few researches on the detection of vertical visibility. Usually, balloons or lights are used for observation. The vertical visibility distance measured by this method is the height invisible to the balloon or light, and it is not necessarily the real vertical visibility of the atmosphere. Moreover, launching balloons for vertical visibility detection is too expensive and not the best vertical visibility detection method.

At present, the methods used to measure horizontal visibility mainly include visual inspection, transmission type visibility meter, and scattering type visibility meter. It is generally called a transmissive visibility meter as a transmissive meter, and the transmissive meter is the earliest visibility measuring instrument. The earliest developed is the single-ended transmissometer. Due to its bulky structure, inconvenient use and installation, difficult processing of the reflector used in the instrument, and the error is difficult to overcome, this kind of transmissometer has been eliminated. After the single-ended transmission meter, a double-ended transmission meter appeared. This kind of transmission meter overcomes the shortcomings of the single-ended transmission meter. After continuous improvement, it has been applied until now, and the measurement theory is relatively mature. The other is the scattering type. When light passes through the atmosphere, the extinction effect is mainly caused by absorption and scattering, and the absorption depends largely on the length of the atmosphere. If the atmospheric length is sufficiently small, the absorption effect is negligible, and based on this, the visibility value can be determined if the extinction effect due to scattering can be measured. The fact that the atmospheric length is sufficiently small indicates that the measurement of scattered light does not require a baseline, which overcomes the shortcomings of the transmission meter. With the advent of scattering theory, scatterometers were quickly developed. According to the scattered light received by the receiver in different directions, the scatterometer can be divided into three types: side scatterometer, backscatterer and forward scatterer. However, these methods have limitations for measuring vertical visibility. Nowadays, it is still very difficult to observe the vertical visibility. First of all, the vertical visibility is observed manually without a specific target reference object, which brings difficulties to the observation, and the observation results are uncertain. Secondly, the aerosol is not uniform in the vertical direction, which leads to the failure of the relationship between visibility and extinction coefficient, that is, the relational expression is not applicable to the calculation of vertical visibility. In addition, experiments have shown that due to the different types of ground aerosols, their optical properties are also very different, resulting in an unstable relationship between aerosol extinction and visibility, which increases the difficulty of vertical visibility detection.

The laser ceilometer is an automatic cloud observation device based on the principle of laser radar. It can obtain the extinction coefficient at different heights to obtain the vertical visibility of the atmosphere. Effects of differences in the relationship between extinction coefficient and visibility on vertical visibility.

Contents of the invention

The purpose of the present invention is to solve the defects in the prior art, to provide a method that can overcome the influence of the difference in the relationship between the extinction coefficient and the visibility on the vertical visibility caused by the different microphysical characteristics of the atmospheric sol particles, and obtain a more accurate vertical visibility of the atmosphere. Measurement methods.

In order to achieve the above object, the invention provides a kind of measuring method of atmospheric vertical visibility, the method may further comprise the steps:

(1) Measure the visibility value V1 and atmospheric aerosol extinction coefficient α by using a visibility meter and a laser ceilometer;

(2) Collect multiple sets of visibility values V1 and atmospheric aerosol extinction coefficient α through step (1), and perform fitting to determine the relationship between them V=f(α) ;

(3) Use the relational formula V=f(α) determined in step (2) to obtain the visibility V _i at different heights, the distance length L _i corresponding to the visibility, and the extinction coefficient α _i at different heights, and calculate the different The contrast attenuation ε _i ' at the distance length, so as to obtain the atmospheric transmittance at different heights;

(4) Integrate the atmospheric transmittance at multiple vertically increasing heights of the atmosphere, and finally calculate the atmospheric vertical visibility V _T .

Among them, the atmospheric aerosol extinction coefficient α in step (1) is preferably the extinction coefficient at a height of 20 m measured by the laser ceilometer.

In step (2), linear fitting is performed on multiple sets of visibility values V1 and atmospheric aerosol extinction coefficient α, and the relationship between the two is determined as: , where a=-1.48, b=5.23, a and b are empirical values obtained from experiments, and the unit of V is km.

Contrastive attenuation ε _i ' at different distance lengths in step (3): , the atmospheric transmittance is: .

Atmospheric vertical visibility V _T in step (4) is: .

The present invention also provides an atmospheric vertical visibility monitoring system adopting the above measurement method, the monitoring system includes a visibility meter, a computer and a laser ceilometer; the computer is connected with the visibility meter and the laser ceilometer respectively.

The above-mentioned visibility meter adopts the forward scattering type visibility meter.

Compared with the prior art, the present invention has the following advantages:

1. Use the existing instruments to better combine the measurement data characteristics of the diffuse visibility meter and the laser ceilometer, which is convenient and accurate;

2. Overcome the influence of the difference in the relationship between extinction coefficient and visibility due to the different microphysical properties of atmospheric aerosol particles on vertical visibility;

3. Use the scattering visibility meter to establish the relationship between the surface extinction coefficient profile and the visibility, and apply this relationship to the visibility profile measured by the laser ceilometer to obtain the high-altitude atmospheric visibility. This set of methods can be applied to measurement in various environments Atmospheric vertical visibility in various regions;

4. The monitoring system of the present invention can utilize the laser visibility meter and the laser ceilometer to monitor the vertical visibility in real time around the clock without unattended observation.

Description of drawings

Fig. 1 is the flow chart of atmospheric vertical visibility measurement method of the present invention;

Fig. 2 is a structural block diagram of the atmospheric vertical visibility monitoring system of the present invention.

Detailed ways

Below in conjunction with accompanying drawing, the present invention is described in detail.

As shown in Figure 2, the atmospheric vertical visibility monitoring system of the present invention includes a computer, a forward scattering visibility meter and a laser ceilometer. The computer is respectively connected with the forward scattering visibility meter and the laser ceilometer.

As shown in Figure 1, the present invention is as follows to the mensuration step of atmospheric vertical visibility:

a. Visibility V1 is measured by forward scattering visibility meter (forward scattering visibility meter emits laser light into the atmosphere, scatters the laser light and suspended particles and receives the transmitted light pulse, and gathers them on the receiving surface of the silicon photoelectric sensor On, the optical signal is converted into an electrical signal, sent to the controller for processing, and then the visibility value V1 is calculated by CPU sampling);

b. Use the laser ceilometer to measure the extinction coefficient α of atmospheric aerosols (the laser ceilometer vertically emits laser pulses into the atmosphere, and receives the scattered light after the laser pulses scatter with atmospheric aerosols, water vapor, and atmospheric molecules , the optical signal is converted into a photocurrent and sent to the laser processing system, and the data is analyzed and processed according to the set program, so as to realize the measurement of the atmospheric aerosol extinction coefficient α);

c. The computer controls the forward scattering visibility meter and the laser ceilometer to work in the same area at different times and in different climates. The forward scattering visibility meter obtains multiple sets of visibility V1. Multiple sets of corresponding extinction coefficient α are obtained at the feedback height, input into the computer, and linear fitting is performed on each set of data at different heights (such as linear fitting for multiple sets of visibility and corresponding extinction coefficients at 10m, multiple sets of Visibility and the corresponding extinction coefficient at 20m for linear fitting, linear fitting for multiple groups of visibility and corresponding extinction coefficient at 30m, etc.), the fitting results show that the laser ceilometer measured the extinction coefficient at 20m and visibility The fitting effect is the best, and the relationship between visibility and extinction coefficient is obtained: , where a=-1.48, b=5.23;

d. Use the above relation to obtain the visibility V _i at different heights in the vertical direction; according to Koschmieder’s law, use the visibility V _i at different heights in the vertical direction, the distance length L _i corresponding to the visibility, and different The extinction coefficient α _i at the height is used to calculate the contrast attenuation ε _i ' at different distance lengths: , so that the atmospheric transmittance at different heights can be obtained as: , and finally calculate the atmospheric vertical visibility V _T : .

Claims (8)

1. a method for measuring atmospheric vertical visibility, is characterized in that, comprises the following steps: (1) Measure the visibility value V1 and atmospheric aerosol extinction coefficient α by using a visibility meter and a laser ceilometer; (2) Collect multiple sets of visibility values V1 and atmospheric aerosol extinction coefficient α through step (1), and perform fitting to determine the relationship between them V=f(α) ; (3) Use the relational formula V=f(α) determined in step (2) to obtain the visibility V _i at different heights, the distance length L _i corresponding to the visibility, and the extinction coefficient α _i at different heights, and calculate the different The contrast attenuation ε _i ' at the distance length, so as to obtain the atmospheric transmittance at different heights; (4) Integrate the atmospheric transmittance at the vertically increasing heights of multiple sets of atmosphere, and finally calculate the atmospheric vertical visibility V _T . 2. The assay method according to claim 1, wherein the atmospheric aerosol extinction coefficient α in the step (1) adopts the extinction coefficient at a height of 20 m measured by a laser ceilometer. 3. The measurement method according to claim 2, characterized in that, in the step (2), linear fitting is performed on multiple sets of visibility values V1 and atmospheric aerosol extinction coefficient α, and the relationship between the two is determined as: , where a=-1.48, b=5.23, V unit is km. 4. The measurement method according to claim 3, characterized in that, the comparison ε _i ' at different distance lengths in the step (3): , the atmospheric transmittance is: . 5. The measuring method according to claim 4, characterized in that, the atmospheric vertical visibility V _T in the step (4) is: . 6. The measuring method according to claim 1, characterized in that, the visibility meter adopts a forward scattering visibility meter. 7. an atmospheric vertical visibility monitoring system adopting the described measuring method of claim 1, is characterized in that, described monitoring system comprises visibility instrument, computer and laser ceilometer; Described computer is connected with visibility instrument and laser ceilometer respectively connected. 8. The monitoring system according to claim 7, wherein the visibility meter is a forward scattering visibility meter.