An atmospheric correction method based on ground atmospheric parameters and atmospheric transmission software

Abstract

The application discloses an atmospheric correction method based on ground atmospheric parameters and atmospheric transmission software, and relates to the technical field of atmospheric correction. The method is based on easily obtained ground atmospheric parameters, combined with average atmospheric parameter profiles of daily averages of nearby meteorological sounding sites in previous years, to obtain real-time atmospheric parameter profiles. The average atmospheric transmittance, atmospheric path radiation and atmospheric background radiation of each waveband required for measuring the radiation characteristics of space targets are calculated by using self-developed CART software, to remove the influence of atmospheric transmission, and the intrinsic radiation characteristics of the target are obtained after atmospheric correction. The application can obtain real-time atmospheric parameter profiles close to actual values, thereby obtaining average atmospheric transmittance, atmospheric path radiation and atmospheric background radiation with high precision, and providing an atmospheric correction method with high efficiency, reliability, low cost and certain precision for removing the atmospheric influence on space target radiation characteristic measurement, and the real-time performance and practicality are good.

Description

Technical Field

[0001] This invention relates to the field of atmospheric correction technology, and in particular to an atmospheric correction method based on ground atmospheric parameters and atmospheric transmission software. Background Technology

[0002] The radiation signal received by photoelectric measurement (or remote sensing) equipment operating in the atmosphere from a target is atmospherically modulated. This signal includes both the target signal attenuated by atmospheric transmission and path path radiation (solar radiation and its thermal radiation scattered by the atmosphere and the Earth's surface). To obtain the intrinsic radiation characteristics of the target, the effects of atmospheric transmission must be quantitatively subtracted. The main purpose of atmospheric transmission correction for target radiation is to quantitatively obtain the atmospheric transmission characteristics, atmospheric path radiation, and atmospheric background radiation characteristics, subtracting these effects to obtain the intrinsic radiation characteristics of the target.

[0003] Currently, the common method for correcting atmospheric transmission in target radiative measurements is to develop atmospheric parameter profile detection equipment to simultaneously detect important atmospheric parameters affecting atmospheric transmission (such as using lidar to detect the atmospheric aerosol extinction height distribution profile, and using microwave radiometers or radiosondes to detect the atmospheric water vapor and temperature height distribution profiles). This is then combined with atmospheric radiative transmission models to calculate the atmospheric transmittance and background radiation for a given band. Because atmospheric parameter profile detection equipment is relatively expensive and has high observation requirements, many target characteristic detection operations lack such equipment but still require data on atmospheric transmittance and background radiation. In such cases, a common method is to use atmospheric radiative transmission model software and standard atmospheric model parameters to calculate atmospheric transmittance and background radiation. However, because standard atmospheric data only represents the average atmospheric parameters of a specific latitude band and often differs significantly from actual atmospheric parameter profiles, using atmospheric transmittance calculated by standard atmospheric models and radiative transmission software to correct for space target radiative characteristic measurements may introduce significant errors. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this invention provides an atmospheric correction method based on ground atmospheric parameters and atmospheric transmission software, which provides an efficient, reliable, low-cost atmospheric correction method with a certain degree of accuracy for the atmospheric influence subtraction of space target radiation characteristic measurement.

[0005] To achieve the above objectives, the present invention adopts the following technical solution, including:

[0006] An atmospheric correction method based on ground atmospheric parameters and atmospheric transport software includes the following steps:

[0007] S1: Obtain ground atmospheric parameters from the ground atmospheric parameter measuring instrument at the observation point, and obtain the location of the observation point, i.e., latitude and longitude information and time information;

[0008] S2, based on the radiosonde data from meteorological radiosonde stations near the observation point over the years, the average atmospheric parameter profile of the area where the observation point is located is obtained in advance, and the model values ​​of atmospheric parameters at different altitudes are obtained.

[0009] S3, based on the real-time ground atmospheric parameters observed at the observation point, corrects the average atmospheric parameter profile of the region where the observation point is located, constructs the real-time atmospheric parameter profile at the observation point, and obtains the corrected values ​​of atmospheric parameters at different altitudes in real time; at the same time, the trace gas composition profile is constructed using the same latitude standard atmospheric model.

[0010] S4. Input the real-time atmospheric parameter profile and trace gas composition profile constructed in step S3 into the atmospheric transmission software, namely CART software. Based on the observation path and observation band of the space target observation equipment, calculate the average atmospheric transmittance, atmospheric path radiation and atmospheric background radiation of the observation band.

[0011] S5. From the measurement signal of the space target observation equipment, i.e. the apparent radiation of the space target being measured, the atmospheric path radiation is first subtracted, and then divided by the average atmospheric transmittance to obtain the intrinsic radiation of the space target being measured.

[0012] Preferably, in step S3, a scaling factor f is introduced for the atmospheric parameter x. x (h), where h is the altitude, and the altitude of the observation point is set to h0;

[0013] At the altitude h0 (usually the surface altitude) of the observation point, the surface scale factor f of atmospheric parameter x is... x (h0) is:

[0014]

[0015] Where x(h0) represents the real-time observed value of atmospheric parameter x at an elevation h0 above the Earth's surface. m (h0) represents the model value of atmospheric parameter x at an altitude of h0, and the subscript m represents the model value;

[0016] h1 x The maximum interpolated height for atmospheric parameter x;

[0017] When h≥h1 x Above this altitude range, the atmospheric parameter x has a scaling factor f at and above the maximum interpolation altitude. x (h) = 1.0, that is, f x (h≥h1 x =1.0;

[0018] In h0≤h x ​Within this altitude range, the scaling factor f for atmospheric parameter x x (h) Obtain the scaling factor f of atmospheric parameter x at different altitudes h by linear interpolation at different altitudes. x The value of (h) is:

[0019]

[0020] When h≥h1 x Within this altitude range, the corrected values ​​of atmospheric parameter x at different altitudes h are:

[0021] x(h)=x m (h)

[0022] In h0≤h x Within this altitude range, the corrected values ​​of atmospheric parameter x at different altitudes h are:

[0023] x(h)=x m (h)×f x (h)

[0024] This allows for real-time atmospheric parameter profiles and the generation of corrected atmospheric parameter values ​​at different altitudes.

[0025] Preferred atmospheric parameters x include: temperature t, air pressure p, and water vapor density h2o;

[0026] For temperature t, the maximum interpolation height of temperature t is h1. t =30km; t(h0) is the real-time observed temperature t at altitude h0, i.e., the ground temperature.

[0027] For pressure p, the maximum interpolation height of pressure p is h1. p =30km; p(h0) is the real-time observed air pressure p at altitude h0, i.e., the ground air pressure value;

[0028] For water vapor density h2o, the maximum interpolation height of water vapor density h2o is h1. h2o =10km; h2o(h0) is the real-time observed value of water vapor density h2o at an altitude of h0, i.e., the ground water vapor density value.

[0029] Preferably, in step S2, the average atmospheric parameter profile of the area where the observation point is located is obtained in advance based on daily averages.

[0030] Preferably, in step S3, the trace gas components include: carbon dioxide, ozone, carbon monoxide, nitrous oxide, and methane.

[0031] Preferably, in step S5, the intrinsic radiation I of the measured space target after atmospheric correction is...​r for:

[0032]

[0033] In the formula, I m For space target observation equipment, the measurement signal is the apparent radiance of the space target being measured; I c-atm Atmospheric path radiation for the observation band calculated by CART software; The average atmospheric transmittance of the observed band calculated by CART software; I r The intrinsic radiation of the measured space target.

[0034] Preferably, in step S4, the constructed real-time atmospheric parameter profile and trace gas composition profile are input into the atmospheric transmission software, namely CART software. The CART software is used to calculate the atmospheric transmittance, atmospheric path radiation and atmospheric background radiation at each wavelength point on a given path and a given band.

[0035] Preferably, for the observation band of the space target observation equipment, the atmospheric path radiation I of the observation band is... c-atm for:

[0036]

[0037] In the formula, I c-atm For observation of atmospheric path radiation in the band; I c-atm (v) represents the atmospheric path radiation at wavelength point v; v1 and v2 are the lower limit and upper limit of the observation band of the space target observation equipment, respectively, and [v1,v2] is the observation band of the space target observation equipment.

[0038] Preferably, for the observation band of the space target observation equipment, the atmospheric background radiation I of the observation band is... c-bck for:

[0039]

[0040] In the formula, I c-bck For the observation band of atmospheric background radiation; I c-bck (v) represents the atmospheric background radiation at wavelength v; v1 and v2 are the lower and upper limits of the observation band of the space target observation equipment, respectively, and [v1,v2] is the observation band of the space target observation equipment.

[0041] Preferably, for the observation band of the space target observation equipment, the average atmospheric transmittance T of the observation band is:

[0042]

[0043] In the formula, f(v) represents the relative distribution of the instrument's spectral response; v1 and v2 are the lower and upper limits of the observation band of the space target observation equipment, respectively, and [v1,v2] is the observation band of the space target observation equipment; T(v) is the atmospheric transmittance at wavelength v; and T is the average atmospheric transmittance of the observation band.

[0044] The advantages of this invention are:

[0045] (1) In addition to using general atmospheric radiation transfer software (CART) and historical sounding databases, this invention only requires conventional ground atmospheric parameters (such as ground atmospheric temperature, relative humidity, water vapor density, air pressure, visibility, etc.) to obtain the intrinsic radiation of the space target being measured. It is low in cost, has good real-time performance, and has a certain degree of accuracy, and will be widely used in many optoelectronic engineering projects.

[0046] (2) Based on the radiosonde data of meteorological radiosonde stations near the observation point over the years, the average atmospheric parameter profile of the region on a daily average basis is obtained, which can represent the average value of the region on that day; combined with the real-time, in-situ ground conventional atmospheric parameter profile at the observation point after correction, it is close to the actual atmospheric parameter profile, with temperature error generally not exceeding 3K and total water vapor error generally not exceeding 20%.

[0047] (3) Using atmospheric transmission software, namely CART software, the calculation accuracy is high. The accuracy of atmospheric transmittance calculation is higher than that of MODTRAN of the U.S. Air Force Geophysical Laboratory. Compared with the industry benchmark of the line-by-line integral radiative transfer mode (LBLRTM) with the highest calculation accuracy, the relative error of the calculated atmospheric transmittance does not exceed 3%.

[0048] (4) Taking all factors into consideration, the atmospheric correction error of the method of the present invention is less than 15% under clear and cloudless weather conditions for bands with an average atmospheric transmittance greater than 50%. Compared with the use of standard atmosphere and atmospheric radiation transmission software widely used abroad, the accuracy of the method of the present invention is greatly improved, which has important application value for many optoelectronic engineering projects.

[0049] (5) This invention uses readily available conventional ground atmospheric parameters (including ground temperature, air pressure, relative humidity, and visibility) combined with the daily average atmospheric parameter profiles from nearby meteorological sounding stations over the years to obtain a real-time atmospheric parameter profile. Using self-developed CART software, the average atmospheric transmittance and background radiation of each band required for measuring the radiation characteristics of space targets are calculated to subtract the influence of atmospheric transmission. After atmospheric correction, the intrinsic radiation characteristics of the target are obtained. This invention has good real-time performance and practicality. In the absence of actual measured real-time atmospheric parameter profiles, this invention can obtain real-time atmospheric parameter profiles that are close to the actual ones, thereby obtaining high-precision average atmospheric transmittance and background radiation. This provides an efficient, reliable, low-cost, and relatively accurate atmospheric correction method for subtracting atmospheric influences in the measurement of the radiation characteristics of space targets. Attached Figure Description

[0050] Figure 1 This is a flowchart of an atmospheric correction method based on ground atmospheric parameters and atmospheric transport software.

[0051] Figure 2 This is a schematic diagram of near-real-time temperature profile reconstruction.

[0052] Figure 3 This is a schematic diagram showing how the temperature scaling factor changes with altitude.

[0053] Figure 4 This is a schematic diagram of the near-real-time water vapor density profile reconstruction.

[0054] Figure 5 This is a schematic diagram showing how the water vapor density proportionality factor changes with altitude.

[0055] Figure 6 This is a schematic diagram of atmospheric spectral transmittance calculated using CART software. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] The atmospheric transmission software CART used can calculate atmospheric spectral transmittance, single and multiple scattering radiance, direct solar irradiance, and atmospheric and surface thermal radiation based on atmospheric parameters, spatial geometric parameters, and spectral band range observation bands. For details of the independently developed CART software, please refer to existing technologies.

[0058] Example 1

[0059] Depend on Figure 1 As shown, an atmospheric correction method based on ground atmospheric parameters and atmospheric transport software includes the following steps:

[0060] S1 obtains ground atmospheric parameters from the ground atmospheric parameter measuring instrument at the observation point, including ground temperature, relative humidity (i.e., water vapor density), air pressure, and visibility, and obtains the location of the observation point (i.e., latitude and longitude information) and time information.

[0061] Conventional automatic weather stations or simple thermometers, hygrometers, and barometers can be used to measure routine atmospheric parameters at ground level; visibility is obtained using a visibility meter or by experienced personnel estimating it visually. Because meteorological visibility and human visual observation typically assume a contrast ratio of 5%, while visibility is strictly defined as the distance at which the contrast ratio drops to 2%, the visibility obtained from meteorological observations needs to be multiplied by a coefficient F.

[0062]

[0063] The visibility obtained by a visibility meter or by human eye needs to be multiplied by 1.3 to obtain the visibility required for CART calculation.

[0064] S2. Based on the radiosonde data from meteorological radiosonde stations near the observation point over the years, the average atmospheric parameter profile of the area where the observation point is located is obtained in advance by daily average, and the model values ​​of atmospheric parameters at different altitudes are obtained.

[0065] The China Meteorological Administration and the World Meteorological Organization have established numerous upper-air sounding stations. These stations launch sounding balloons daily at 8:00 AM and 8:00 PM Beijing time to measure atmospheric temperature, humidity, air pressure, and wind from the ground to an altitude of approximately 30 km. In this embodiment, the distribution of 91 major meteorological sounding stations in my country with continuous cumulative data exceeding 10 years was collected. Generally, there is one upper-air atmospheric parameter sounding station within a distance range of 200-400 km; therefore, a meteorological sounding station can usually be found within a 200 km range. We statistically analyzed an average of two sets of sounding data exceeding 10 years per day to obtain the average atmospheric parameter profiles for each meteorological sounding station. Taking the Chengdu area as an example, as... Figure 2 and Figure 4 The square curve represents the average profiles of atmospheric temperature and water vapor in the Chengdu area on June 30th. Temperature and water vapor are the most important atmospheric parameters for calculating infrared atmospheric transmittance and thermal radiation.

[0066] S3, based on the real-time observed ground atmospheric parameters at the observation point, corrects the average atmospheric parameter profile of the region where the observation point is located, constructs the real-time atmospheric parameter profile at the observation point, and obtains the corrected values ​​of atmospheric parameters at different altitudes in real time; at the same time, the trace gas composition profile is constructed using the same latitude standard atmospheric model, and the trace gas components include carbon dioxide, ozone, carbon monoxide, nitrous oxide and methane, etc.

[0067] Based on in-situ measurements of atmospheric parameters obtained from real-time observation points, the daily average temperature, air pressure, and water vapor density profiles for that day are interpolated using a scaling factor, combined with real-time surface atmospheric temperature, relative humidity, and air pressure parameters, to obtain the atmospheric parameter profiles at the time of measurement. For atmospheric temperature and pressure profiles above 30 km and water vapor density profiles above 10 km, the corresponding standard atmospheric model is referenced based on the latitude and month of the observation point. The specific method is as follows:

[0068] A scaling factor f is introduced for the atmospheric parameters x (where x represents atmospheric temperature t, air pressure p, and water vapor density h2o, respectively). x (h), where h is the altitude, and the altitude of the observation point is set to h0;

[0069] At the altitude h0 of the observation point, the surface scale factor f of atmospheric parameter x is... x (h0) is:

[0070]

[0071] In the formula, x(h0) represents the real-time observed value of atmospheric parameter x at an altitude of h0. m (h0) represents the model value of atmospheric parameter x at altitude h0, x m (h1 x () represents the model value of atmospheric parameter x at the maximum interpolation height h1, where h1 x The maximum interpolated altitude for atmospheric parameter x; the subscript m represents the model value;

[0072] The scaling factor f of atmospheric parameter x x (h) is used for interpolation, and the maximum interpolation height of atmospheric parameter x is h1. x ;

[0073] When h≥h1 x Within this altitude range, the atmospheric parameter x and the scaling factor f above the maximum interpolation altitude. x (h) = 1.0, that is, f x (h≥h1 x =1.0;

[0074] In h0≤h x ​Within this altitude range, the scaling factor f for atmospheric parameter x x (h) Obtain the scaling factor f of atmospheric parameter x at different altitudes h by linear interpolation at different altitudes. x The value of (h) is:

[0075]

[0076] When h≥h1 x Within this altitude range, the corrected values ​​of atmospheric parameter x at different altitudes h are:

[0077] x(h)=x m (h)

[0078] In h0≤h x Within this altitude range, the corrected values ​​of atmospheric parameter x at different altitudes h are:

[0079] x(h)=x m (h)×f x (h)

[0080] This allows for real-time atmospheric parameter profiles and the generation of corrected atmospheric parameter values ​​at different altitudes.

[0081] In this embodiment, the atmospheric parameter x includes: temperature t, air pressure p, and water vapor density h2o.

[0082] For temperature t, the maximum interpolation height is h1. t =30km;

[0083] At the altitude h0 of the observation point, the surface scale factor f of temperature t is... t (h0) is:

[0084]

[0085] When h≥h1 t Within this altitude range, the temperature t is at the maximum interpolation altitude and the scaling factor f above the maximum interpolation altitude. t (h) = 1.0;

[0086] In h0≤h t Within this altitude range, the scaling factor f for temperature t t (h) Linear interpolation based on height yields the scaling factor f of temperature t at different heights h. t The value of (h) is:

[0087]

[0088] When h≥h1 t Within this height range, the correction values ​​t(h) for temperature t at different heights h are:​​

[0089] t(h)=t m (h)

[0090] In h0≤h t Within this height range, the correction values ​​t(h) for temperature t at different heights h are:

[0091] t(h)=t m (h)×f t (h)

[0092] t(h0) is the real-time observed temperature t at an altitude of h0, i.e., the ground temperature. m (h0) is the model value of the temperature t at altitude h0, i.e., the observation point; t m (h1 t () represents the model value of temperature t at the maximum interpolation height h1; h1 t This represents the maximum interpolation height for temperature t.

[0093] For pressure p, the maximum interpolation height of pressure p is h1. p =30km;

[0094] At the altitude h0 of the observation point, the surface scale factor f of the air pressure p p (h0) is:

[0095]

[0096] When h≥h1 p Within this altitude range, the air pressure p is at the maximum interpolation altitude and the scaling factor f above the maximum interpolation altitude. p (h) = 1.0;

[0097] In h0≤h p Within this altitude range, the scaling factor f for air pressure p p (h) Obtain the scaling factor f of air pressure p at different altitudes h by linear interpolation based on altitude. p The value of (h) is:

[0098]

[0099] When h≥h1 p Within this altitude range, the correction values ​​p(h) for the air pressure p at different altitudes h are:

[0100] p(h)=p m (h)

[0101] When h < h1 p Within this altitude range, the correction values ​​p(h) for the air pressure p at different altitudes h are:​​

[0102] p(h)=p m (h)×f p (h)

[0103] p(h0) is the real-time observed air pressure p at an altitude of h0, i.e., the surface air pressure value; p m (h0) is the model value of the air pressure p at an altitude of h0, i.e., at the viewpoint; p m (h1 p The value of ) represents the model value of the air pressure p at the maximum interpolation height h1; h1 p The maximum interpolated height is the air pressure p.

[0104] For water vapor density h2o, the maximum interpolation height of water vapor density h2o is h1. h2 o = 10km;

[0105] At the altitude h0 of the observation point, the surface scale factor f of the water vapor density h2o h2 o(h0) is:

[0106]

[0107] When h≥h1 h2 Within this altitude range, the water vapor density h2o's scaling factor f at and above the maximum interpolation altitude. h2o (h) = 1.0;

[0108] In h0≤h h2o Within this altitude range, the scaling factor f for water vapor density h2o h2 The scaling factor f of water vapor density h2o at different heights h is obtained by linear interpolation of o(h) according to height. h2o The value of (h) is:

[0109]

[0110] When h≥h1 h2o Within this altitude range, the corrected values ​​of water vapor density h2o at different altitudes h are:

[0111] h2o(h)=h2o m (h)

[0112] When h < h1 h2o Within this altitude range, the corrected values ​​of water vapor density h2o at different altitudes h are:

[0113] h2o(h)=h2o m (h)×f h2o (h) ​

[0114] h2o(h0) is the real-time observed value of water vapor density h2o at an altitude of h0, i.e., the ground water vapor density value; h2o m (h0) is the model value of water vapor density h2o at an altitude of h0, i.e., at the viewpoint; h2o m (h1 h2o The value of h2o represents the water vapor density at the maximum interpolation height h1; h1 is the model value. h2o The maximum interpolation height for water vapor density h2o.

[0115] Using the methods described above, real-time atmospheric parameter profiles can be obtained based on real-time ground atmospheric parameters and historical sounding data. Additionally, the atmospheric density height distribution profile can be calculated from the constructed atmospheric temperature and pressure height distribution profiles using hydrostatic equations; the atmospheric nitrogen height distribution profile can be calculated using a volume mixing ratio of 78.05%; and the atmospheric oxygen height distribution profile can be calculated using a volume mixing ratio of 20.94%.

[0116] Figures 2-5 A set of temperature and water vapor profiles, adjusted based on actual ground measurements near Chengdu and the average temperature and average water vapor profiles for Chengdu on June 30, are provided. Figure 3 and Figure 5 These are the scaling factors for temperature adjustment and moisture adjustment, respectively. For example, if the measured atmospheric temperature at ground level is 31.2℃, the relative humidity is 65.3%, and the air pressure is 945hPa, while the historical average profile ground temperature for that day is 295.43K, and the ratio of the measured to the historical ground temperature is 1.0302, then the ground temperature scaling factor is 1.0302, and the temperature adjustment scaling factor at an altitude of 30km is 1.000. This is obtained by linear interpolation from h0 to 30km altitude. Figure 3 Temperature adjustment scaling factor profile, Figure 2 The circular curve in the figure represents the adjusted real-time temperature profile. Similarly, the real-time surface water vapor mixing ratio, calculated from temperature, relative humidity, and air pressure, is 31517 ppmv, while the historical average surface water vapor mixing ratio is 24763 ppmv, resulting in a ratio of 1.273. This ratio is linearly interpolated to a height of 10 km, yielding a value of 1. The water vapor adjustment factor profile curve is shown in [reference needed]. Figure 5 The adjusted real-time water vapor profile is shown below. Figure 4Because surface atmospheric parameters are measured in real time, and water vapor is mainly distributed in the lower troposphere near the surface, the real-time atmospheric parameter profile can be obtained using the above method based on real-time surface atmospheric parameters and historical radiosonde data. The temperature error is generally less than 3K, and the total water vapor error is generally less than 20%. Under clear, cloudless weather conditions, the atmospheric transmittance correction error using this method is less than 15% for bands with an average atmospheric transmittance greater than 50%. Compared to using standard atmospheric conditions and widely used atmospheric radiative transfer software, the accuracy of this invention is greatly improved, which has significant application value for many optoelectronic engineering projects.

[0117] S4. Input the real-time atmospheric parameter profile and trace gas composition profile constructed in step S3 into the atmospheric transmission software, namely CART software. Based on the observation path and observation band of the space target observation equipment, calculate the average atmospheric transmittance, atmospheric path radiation, and atmospheric background radiation of the observation band.

[0118] In the CART software, a medium-to-high resolution atmospheric molecular absorption algorithm based on line-by-line integration and a fast discrete coordinate calculation algorithm based on the combined rearrangement of atmospheric absorption and scattering are proposed. These algorithms consider the absorption, scattering, and thermal radiation effects of atmospheric molecules and aerosol particles, as well as the reflection and radiation effects of the Earth's surface. They can be used to quickly calculate atmospheric transmittance, scattering, and thermal radiation between any two points in space, as well as solar radiation reflected from the Earth's surface and thermal radiation from the Earth's surface and atmosphere. The spectral band is from the visible light band to the far-infrared band, i.e., 0.4μm-10000μm, and the spectral resolution is divided into medium resolution 1cm. -1 The CART software calculates the atmospheric transmittance, atmospheric path radiation, and atmospheric background radiation at each wavelength.

[0119] Atmospheric path radiation refers to atmospheric radiation along a specific path and is used for atmospheric transmission correction. Atmospheric background radiation refers to the total atmospheric radiation from the observation point to infinity and is used to estimate target background contrast. When the target is outside the atmosphere, atmospheric path radiation and atmospheric background radiation are the same. CART software calculates the atmospheric transmittance, atmospheric path radiation, and atmospheric background radiation at each wavelength point, then obtains the average atmospheric transmittance of the band using the following formula, and obtains the atmospheric path radiation and atmospheric background radiation of the band by wavelength integration.

[0120] For the observation bands of space target observation equipment, the average atmospheric transmittance T of the observation bands is:

[0121]

[0122] In the formula, f(v) is the relative distribution of the instrument spectral response of the space target observation equipment; v1 and v2 are the lower limit and upper limit of the observation band of the space target observation equipment, respectively, and [v1,v2] is the observation band of the space target observation equipment; T(v) is the atmospheric transmittance at wavelength v; T is the average atmospheric transmittance of the observation band calculated by CART software.

[0123] Atmospheric path radiation in the observation band is obtained by integrating the calculated values ​​at each wavelength:

[0124]

[0125] The atmospheric background radiation in the observed band is obtained by integrating the calculated values ​​at each wavelength:

[0126]

[0127] In the formula, I c-atm For the atmospheric path radiation of the observation band calculated by CART software, I c-atm (v) represents the atmospheric path radiation at wavelength v; I c-bck For the atmospheric background radiation of the observation band calculated by CART software, I c-bck (v) represents the atmospheric background radiation at wavelength v.

[0128] Figure 6 It is the atmospheric transmittance T(v) in the 3μm-12μm band from the ground to the top of the atmosphere (zenith angle 30°) calculated based on the above parameters.

[0129] S5. From the measurement signal of the space target observation equipment, i.e. the apparent radiation of the space target being measured, the atmospheric path radiation is first subtracted, and then divided by the average atmospheric transmittance to obtain the intrinsic radiation of the space target being measured.

[0130] In step S5, the intrinsic radiation Ir of the measured space target after atmospheric correction is:

[0131]

[0132] In the formula, I m I represents the apparent radiance of the measured space target. c-atm T is the atmospheric path radiation of the observation band calculated by CART software; T is the average atmospheric transmittance of the observation band calculated by CART software. This yields the intrinsic radiance of the target after atmospheric transmission correction.

[0133] To estimate the system's effective range, the contrast R between the target and the background needs to be calculated.

[0134]

[0135] In the formula, I m I represents the apparent radiance of the measured space target. c-bck The atmospheric background radiation for the observation band calculated by CART software.

[0136] Example 2

[0137] The system architecture applicable to the method of the present invention includes: a database, a ground atmospheric parameter measuring instrument, a real-time atmospheric parameter profile reconstruction unit, a calculation unit, and a correction unit.

[0138] The database stores the daily average atmospheric parameter profiles of meteorological sounding stations. In this embodiment, the database collects more than 10 years of historical sounding data from 91 major meteorological sounding stations in my country, taken twice daily. After quality control and statistical averaging, the database provides the altitude distribution profiles of average temperature (K) and average air pressure (hPa) from the ground to an altitude of approximately 30 km, and the altitude profile of average water vapor volume mixing ratio (PPMV) from the ground to an altitude of approximately 10 km, taken twice daily (08:00 and 20:00 Beijing time) from 1 to 365 days for these 91 meteorological sounding stations.

[0139] The ground atmospheric parameter measuring instrument is used to measure ground atmospheric parameters (including surface atmospheric temperature, air pressure, humidity, and visibility) in real time.

[0140] The reconstruction unit is used to adjust the scaling factor based on real-time ground-measured atmospheric parameters, correct the average atmospheric parameter profile of the region, and obtain the real-time atmospheric parameter profile.

[0141] The calculation unit is used to calculate the average atmospheric transmittance, atmospheric path radiation, and background radiation under a given path and band, based on real-time atmospheric parameter profiles and trace gas composition profiles. In this embodiment, the calculation unit uses the independently developed CART software.

[0142] The correction unit is used to correct the apparent radiance of the measured space target to obtain the intrinsic radiance of the measured space target.

[0143] The apparent radiance of the measured space target is obtained by the space target observation equipment, and the apparent radiance of the measured space target is the measurement signal of the space target observation equipment.

[0144] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An atmospheric correction method based on ground atmospheric parameters and atmospheric transport software, characterized in that, Includes the following steps: S1, obtains ground atmospheric parameters from the ground atmospheric parameter measuring instrument at the observation point, and obtains the location of the observation point, i.e., latitude and longitude information and time information; atmospheric parameters include temperature, air pressure and water vapor density; S2, based on the radiosonde data from meteorological radiosonde stations near the observation point over the years, the average atmospheric parameter profile of the area where the observation point is located is obtained in advance, and the model values ​​of atmospheric parameters at different altitudes are obtained. S3, based on the real-time observed ground atmospheric parameters at the observation point, corrects the average atmospheric parameter profile of the region where the observation point is located, constructs the real-time atmospheric parameter profile at the observation point, and obtains the corrected values ​​of atmospheric parameters at different altitudes in real time; at the same time, the trace gas composition profile is constructed using the same latitude standard atmospheric model; the trace gas components include: carbon dioxide, ozone, carbon monoxide, nitrous oxide and methane. S4. Input the real-time atmospheric parameter profile and trace gas composition profile constructed in step S3 into the atmospheric transmission software, namely CART software. Based on the observation path and observation band of the space target observation equipment, calculate the average atmospheric transmittance, atmospheric path radiation and atmospheric background radiation of the observation band. S5. From the measurement signal of the space target observation equipment, i.e. the apparent radiation of the space target being measured, first subtract the atmospheric path radiation, and then divide by the average atmospheric transmittance to obtain the intrinsic radiation of the space target being measured. In step S3, Regarding atmospheric parameters Introduce a scaling factor , The altitude of the observation point is set to [height]. At the altitude of the observation point Atmospheric parameters Surface scale factor for: in, Indicates the altitude at the Earth's surface. Atmospheric parameters Real-time observations Indicates altitude Atmospheric parameters pattern value; subscript Represents the pattern value; Atmospheric parameters Maximum interpolation height; when At that time, atmospheric parameters Scale factor above and above the maximum interpolation height ,Right now ; when At that time, for atmospheric parameters Scale factor Atmospheric parameters are obtained by linear interpolation based on altitude. At different heights Scale factor The value is: when At different heights Atmospheric parameters Correction value for: when At different heights Atmospheric parameters Correction value for: This allows for the construction of real-time atmospheric parameter profiles at observation points, and the real-time correction values ​​of atmospheric parameters at different altitudes.

2. The atmospheric correction method based on ground atmospheric parameters and atmospheric transport software according to claim 1, characterized in that, Atmospheric parameters Including: temperature air pressure Water vapor density ; For temperature ,temperature The maximum interpolation height is =30km; Altitude The temperature at the point of view is measured. The real-time observed value, i.e., the ground temperature value; For air pressure air pressure The maximum interpolation height is =30km; Altitude The air pressure at the point of view. The real-time observed value, i.e., the surface air pressure value; For water vapor density Water vapor density The maximum interpolation height is =10km; Altitude The water vapor density at the point of view. The real-time observed value, i.e., the ground water vapor density value.

3. The atmospheric correction method based on ground atmospheric parameters and atmospheric transport software according to claim 1, characterized in that, In step S2, the average atmospheric parameter profile of the area where the observation point is located is obtained in advance based on daily averages.

4. The atmospheric correction method based on ground atmospheric parameters and atmospheric transport software according to claim 1, characterized in that, In step S5, the intrinsic radiation of the measured space target after atmospheric correction is... for: In the formula, The measurement signal of the space target observation equipment is the apparent radiance of the space target being measured. Atmospheric path radiation for the observation band calculated by CART software; The average atmospheric transmittance of the observed band calculated by CART software; The intrinsic radiation of the measured space target.

5. The atmospheric correction method based on ground atmospheric parameters and atmospheric transport software according to claim 1, characterized in that, In step S4, the constructed real-time atmospheric parameter profile and trace gas composition profile are input into the atmospheric transmission software, namely CART software. The CART software is used to calculate the atmospheric transmittance, atmospheric path radiation and atmospheric background radiation at each wavelength point on a given path and a given band.

6. The atmospheric correction method based on ground atmospheric parameters and atmospheric transport software according to claim 5, characterized in that, For the observation bands of space target observation equipment, the atmospheric path radiation of the observation bands for: In the formula, To observe atmospheric path radiation in the band; wavelength point Atmospheric radiation; and These are the lower and upper limits of the observation bands for space target observation equipment, respectively. , This refers to the observation band of space target observation equipment.

7. The atmospheric correction method based on ground atmospheric parameters and atmospheric transport software according to claim 5, characterized in that, For the observation bands of space target observation equipment, the atmospheric background radiation of the observation bands for: In the formula, To observe the atmospheric background radiation in the band; wavelength point Atmospheric background radiation; and These are the lower and upper limits of the observation bands for space target observation equipment, respectively. , This refers to the observation band of space target observation equipment.

8. The atmospheric correction method based on ground atmospheric parameters and atmospheric transport software according to claim 5, characterized in that, For the observation bands of space target observation equipment, the average atmospheric transmittance of the observation bands is... for: In the formula, The relative distribution of the spectral response of instruments used for observing space targets; and These are the lower and upper limits of the observation bands for space target observation equipment, respectively. , This refers to the observation band of space target observation equipment; wavelength point Atmospheric transmittance; This represents the average atmospheric transmittance of the observed band.

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