CN113639970A - Method for evaluating ground detection calibration capability of satellite lightning imager - Google Patents
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Abstract
The application provides a method for evaluating the detection ground calibration capability of a satellite lightning imager, and relates to the technical field of satellite lightning imager detection capability evaluation. The method comprises the steps of acquiring multi-station three-dimensional lightning detection network data of lightning; calculating the spatial position and occurrence time of each radiation source pulse of lightning; calculating the number of lightning stroke strokes according to the space position and the occurrence time of each radiation source pulse; acquiring the number of groups of lightning satellites by using a wind cloud number four satellite lightning imager; and determining the detection capability of the satellite lightning imager according to the comparison result of the number of the strobing strobes and the number of the satellite groups. The method calculates the number of the flash strokes of the lightning by analyzing the space position and the occurrence time of each radiation source pulse, solves the problem that the number of the flash strokes is inconsistent with the number of groups detected by a satellite lightning imager in space and time, and evaluates the ground calibration capability of the satellite lightning imager in detection more scientifically.
Description
Technical Field
The application relates to the technical field of satellite lightning detection capability assessment, in particular to a method for assessing ground calibration capability of a satellite lightning imager.
Background
A new generation of FY4 satellite of static meteorological satellite aeolian cloud with the characteristic of being launched in 2016, 12, 11 and the like in China realizes the continuous monitoring of static orbit lightning in Asian oceania areas for the first time by a satellite lightning imager (LMI) carried by the satellite lightning imager. The satellite lightning imager adopts a charge coupled device detection array CCD and an optical imaging technology, and realizes staring observation of total flashes including cloud flashes, inter-cloud flashes and cloud-ground flashes in a monitored area through a combination of spectral filtering, spatial filtering, temporal filtering and frame background removal.
When the satellite lightning imager carries out lightning optical detection, due to the severe outer space environment, the interior of the detection instrument and other reasons, the satellite lightning imager detects a large number of false signals, and the false signals also seriously affect the detection result of the satellite lightning imager. Therefore, it is necessary to assess the correctness of the satellite lightning imager detection results.
In the prior art, an evaluation method for directly comparing the number of flash strokes detected by a three-dimensional lightning positioning system with the number of groups detected by a satellite lightning imager is mostly adopted, and the inconsistency of the number of flash strokes and the number of groups detected by the satellite lightning imager in time and space is not considered, so that the method for directly comparing the number of flash strokes with the number of groups cannot correctly evaluate the ground calibration capability of the detection of the satellite lightning imager of the fourth of the wind clouds.
Disclosure of Invention
The method for evaluating the ground calibration capability of the satellite lightning imager is provided by the application, and the defects in the prior art can be overcome.
In order to achieve the technical purpose, the technical scheme adopted by the application is as follows:
a method for evaluating the ground detection calibration capability of a satellite lightning imager comprises the following steps:
acquiring multi-station three-dimensional lightning detection network data of lightning;
calculating the spatial position and occurrence time of each radiation source pulse of the lightning;
calculating the number of lightning stroke strokes according to the space position and the occurrence time of each radiation source pulse;
acquiring the number of the satellite groups of the lightning by using a wind cloud number four satellite lightning imager;
and comparing the number of the strobing strobes with the number of the satellite groups, and evaluating the detection ground calibration capability of the satellite lightning imager.
Further, two or more radiation pulses with spatial positions in a preset area and time intervals of occurrence time in a preset time are equivalent to one click stroke.
Further, the spatial resolution of the preset area is 9.2 km; the preset time is 2 ms.
The technical scheme of the application has the following beneficial effects:
the method for evaluating the ground detection calibration capability of the satellite lightning imager comprises the steps of acquiring multi-station three-dimensional lightning detection network data of lightning; calculating the spatial position and occurrence time of each radiation source pulse of lightning; calculating the number of lightning stroke strokes according to the space position and the occurrence time of each radiation source pulse; acquiring the number of groups of lightning satellites by using a wind cloud number four satellite lightning imager; and determining the detection capability of the satellite lightning imager according to the comparison result of the number of the strobing strobes and the number of the satellite groups. The method calculates the number of the flash strokes of the lightning by analyzing the space position and the occurrence time of each radiation source pulse, solves the problem that the number of the flash strokes is inconsistent with the number of groups detected by a satellite lightning imager in space and time, and more accurately evaluates the ground calibration capability of the satellite lightning imager in detection.
Drawings
In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of a method for evaluating ground targeting capability of a satellite lightning imager according to an embodiment of the present application;
fig. 2 is a relationship between an event and a group detected by a CCD camera of the wind cloud number four satellite lightning imager provided in the embodiment of the present application.
Detailed Description
Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following examples do not represent all embodiments consistent with the present application. But merely as exemplifications of systems and methods consistent with certain aspects of the application, as recited in the claims.
Referring to fig. 1, a schematic diagram of a detection evaluation method of a wind cloud number four satellite lightning imager is shown; referring to fig. 2, the relationship between event and group detected by the CCD camera of the wind cloud number four satellite lightning imager.
The detection evaluation method of the wind cloud number four satellite lightning imager comprises the following steps:
the method comprises the following steps: acquiring multi-station three-dimensional lightning detection network data of lightning. The multi-station three-dimensional lightning detection network data is acquired by utilizing a multi-station three-dimensional positioning system.
Step two: according to the multi-station three-dimensional lightning detection network data, the space position (x, y, z) and the occurrence time t of each radiation source pulse of lightning are calculated by utilizing a TOA time difference location algorithm, and the method specifically comprises the following steps:
based on the waveform cross-correlation technology, the time difference of the lightning radiation source pulse reaching different observation substations is obtained, and if more than 5 observation substations synchronously receive the magnetic signals, the radiation source pulse can be positioned in a three-dimensional space by adopting a time difference of arrival method. Collecting time t of a radiation source signal of the radiation source pulse to an observation substation i from the multi-station three-dimensional lightning detection network dataiThe distance between the observation sub-station and the observation sub-station; the time t of the radiation source signal of the radiation source pulse reaching the observation substation iiThe distance to the observation sub-station is represented by formula (1):
wherein i is 1,2, …, N, said N being the number of observation substations; t is the time when the radiation source pulse is at spatial position (x, y, z); (x)i,yi,zi) Spatial position information for the ith observation substation; and c is the speed of light.
Using t acquired from 5 or more observation substationsiBy substituting formula (1), 5 or more equations as formula (1) can be obtained, and 4 or more time differences can be obtained to form a nonlinear equation set. The occurrence position and time (x, y, z, t) of the lightning pulse radiation source obtained by solving should meet the arrival time difference between each observation sub-station
Measured value and equation ti＝f(xi,yi,ziTime difference of arrival given by x, y, z, t)
The difference is minimal, wherein j is 1,2, …, N-1.
By using Levenberg-Marquardt non-linearFitting the equation (2) by a least square fitting algorithm, and calculating goodness of fit chi2：
Wherein N-4 is a degree of freedom and represents the number of redundant observation sub-stations; sigma is the time measurement precision of each observation substation, and factors such as the time service precision of a GPS clock, the landform and the landform on a lightning signal propagation path, the electromagnetic noise of a site where the observation substation is located and the like influence the sigma, and the sigma is usually 150 ns;
the arrival time difference of the radiation source signal of the radiation source pulse reaching each observation sub-station;
is an equation ti＝f(xi,yi,ziX, y, z, t) is given; j is 1,2, …, N-1. According to the related studies, chi2The larger the value is, the more serious the interference of the environmental noise is, the smaller the power of the radiation source pulse received by the observation substation is, the larger the time measurement error of the observation substation is, and correspondingly, the larger the positioning error of the radiation source pulse is. When x2When the value is more than 5, the actual radiation source pulse heating positioning data is more than the x obtained by solving an equation theoretically2Large distribution deviation, reasonable x2The value should be less than 5.
So the present application states the goodness of fit χ2And taking a minimum value, and calculating to obtain the spatial position and time information (x, y, z, t) of the radiation source pulse.
Step three: and calculating the number of stroke strokes of the lightning.
And analyzing the spatial position (x, y, z) and the occurrence time t of each radiation source pulse, and equating two or more radiation pulses with the spatial position in a preset area and the occurrence time interval in a preset time as a click stroke. And then a plurality of pulses which are generated by lightning and have different magnetic induction intensities are equivalent to a plurality of impact strokes.
The spatial resolution of the preset area is 9.2 km. The exposure time of each frame of the CCD camera of the wind cloud number four satellite lightning imager is 2ms, so that the preset time is set to be 2ms in the embodiment of the application.
Step four: and acquiring the number of the satellite groups of the lightning by using a wind cloud number four satellite lightning imager.
The exposure time of each frame of a CCD camera of the wind cloud number four satellite lightning imager is 2 ms. Referring to fig. 2, the relationship between event and group detected by CCD camera of wind cloud number four satellite lightning imager. Within 2ms, a plurality of pixel point CCDs are lighted, each lighted CCD is called an event, adjacent events are equivalent to one group, and therefore the number of the lightning satellite groups is obtained.
Step five: and determining the detection capability of the satellite lightning imager according to the comparison result of the number of the strobing strobes and the number of the satellite groups.
The method for evaluating the ground detection calibration capability of the satellite lightning imager acquires multi-station three-dimensional lightning detection network data of lightning; calculating the spatial position and occurrence time of each radiation source pulse of lightning; calculating the number of lightning stroke strokes according to the space position and the occurrence time of each radiation source pulse; acquiring the number of groups of lightning satellites by using a wind cloud number four satellite lightning imager; and determining the detection capability of the satellite lightning imager according to the comparison result of the number of the strobing strobes and the number of the satellite groups. The method calculates the number of the flash strokes of the lightning by analyzing the space position and the occurrence time of each radiation source pulse, solves the problem that the number of the flash strokes is inconsistent with the number of groups detected by a satellite lightning imager in space and time, and evaluates the ground calibration capability of the satellite lightning imager in detection more scientifically.
The embodiments provided in the present application are only a few examples of the general concept of the present application, and do not limit the scope of the present application. Any other embodiments extended according to the scheme of the present application without inventive efforts will be within the scope of protection of the present application for a person skilled in the art.
Claims (3)
1. A method for evaluating the ground calibration capability of a satellite lightning imager, which is characterized by comprising the following steps:
acquiring multi-station three-dimensional lightning detection network data of lightning;
calculating the spatial position and occurrence time of each radiation source pulse of the lightning;
calculating the number of lightning stroke strokes according to the space position and the occurrence time of each radiation source pulse;
acquiring the number of the satellite groups of the lightning by using a wind cloud number four satellite lightning imager;
and comparing the number of the strobing strobes with the number of the satellite groups, and evaluating the detection ground calibration capability of the satellite lightning imager.
2. The method of assessing the terrestrial calibration capability of a satellite lightning imager in detection according to claim 1, wherein two or more of the radiation pulses that are spatially located within a predetermined area and occur at a time interval within a predetermined time are equivalent to one strike.
3. A method of assessing a satellite lightning imager's ability to detect ground calibrations, according to claim 1, characterized in that said preset area has a spatial resolution of 9.2 km; the preset time is 2 ms.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117473877A (en) * | 2023-12-27 | 2024-01-30 | 青岛市生态与农业气象中心(青岛市气候变化中心) | Lightning three-dimensional radiation source position inversion method based on stationary satellite data |
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