CN116858290B - Deep open sea surface height observation and calibration method and system based on large unmanned plane - Google Patents

Abstract

The invention discloses a deep sea sea surface height observation and calibration method and system based on a large unmanned aerial vehicle. The system includes a shore-based GNSS reference station, a GNSS integrated observation buoy system and a wave energy profile buoy observation array; the GNSS integrated observation buoy is composed of an upper float, a GNSS antenna, a CTD profiler and a bottom pressure gauge, and is located offshore (~20km) Deploy; the wave energy profile buoy observation array includes a plurality of wave energy profile buoys, and the wave energy profile buoy is composed of an upper float, a profile platform, a crawling steel cable and a bottom pressure gauge. Compared with the traditional airborne altimeter calibration and inspection scheme, the present invention can effectively improve the accuracy of the calibration and inspection of the deep sea, provide more precise calibration values for the airborne altimeter calibration and inspection, and achieve high three-dimensional spatial and temporal resolution of the ocean. authenticity test.

Description

Calibration method and system for sea surface height observation in deep sea based on large unmanned aerial vehicle

Technical field

The invention belongs to the technical field of ocean observation, and specifically relates to a deep sea sea surface height observation and calibration method and system based on a large unmanned aerial vehicle.

Background technique

The altimeter carried by scientific satellites is an indispensable and important tool for marine scientific research. However, during the process of satellite altimetry, its data is uncertain due to the influence of sea state deviation, ionospheric path delay, tide and other factors. The accuracy and drift of the data require strict error term correction and on-site calibration to observe the accuracy and drift of the data. Domestic and foreign altimeter satellites will carry out airborne flight test calibrations multiple times before launch to explore the altimeter calibration scheme. It has become the consensus of researchers to conduct relevant airborne calibration flight tests on the payloads of scientific satellites before they are launched. This is not only It is conducive to technical verification of new payloads and can accumulate a large number of real observation data sets.

At present, most sea surface height observation networks matched with airborne satellite altimeter flight tests often use a combination of shore-based tide gauges and GNSS buoy platforms. However, this solution has the following problems: First, use shore tide gauges to measure sea surface height. When extrapolating, the measurement accuracy of sea surface height is closely related to the accuracy of the tidal model and the geoid; secondly, when using GNSS buoys and their arrays fixed around the platform to invert sea surface height, the measurement accuracy of nearshore elevation can still meet the requirements. However, as the distance from the shore GNSS base station becomes farther and farther, the sea surface precision measured by the GNSS buoy will gradually decrease, and the effect of calibration inspection will decline compared with the offshore area.

Contents of the invention

The purpose of the present invention is to provide a method and system for sea surface altitude observation and calibration in the deep sea based on a large unmanned aerial vehicle to make up for the shortcomings of existing altimeter calibration solutions and improve the accuracy of the calibration and inspection technology in the deep sea.

In traditional airborne radar altimeter on-site observation and calibration systems, tide gauges and GNSS static receiving terminals are often set up on the shore as reference base stations for calculation, and GNSS buoys or GNSS buoy arrays are deployed in relevant test sea areas. The accuracy of such a calibration inspection scheme depends to a large extent on the tidal model and geoid. During the satellite airborne calibration test, the calibration accuracy will decrease as the distance from the shore-based reference station increases. Especially in deep-sea areas far offshore, traditional calibration solutions are no longer able to provide high-precision reference data sets for airborne altimeter calibration.

On the basis of retaining the shore-based GNSS reference station, the present invention introduces a wave energy profile buoy array, and based on this equipment, increases the observation and calculation of temperature and salt profiles.

Based on the above principles, in order to achieve the above objectives, the specific technical solutions adopted by the present invention are as follows:

A deep-sea sea surface height observation and calibration system based on large UAVs. The system includes a shore-based GNSS reference station, a GNSS integrated observation buoy system and a wave energy profile buoy observation array; the GNSS integrated observation buoy consists of an upper floating body, It consists of a GNSS antenna, CTD profiler and bottom pressure gauge, and is deployed offshore (~20km); the wave energy profile buoy observation array includes multiple wave energy profile buoys, and the wave energy profile buoy consists of an upper float and a profile platform. , crawling steel cable and bottom pressure gauge. The system needs to be formed at least 24 hours before the aviation test flight.

Further, the floating body includes a data acquisition module, which is composed of a GNSS receiver board, an attitude compensator and a wireless transmission module; the attitude compensator can accurately and efficiently output the buoy attitude data at a frequency of 50HZ, and the measured data For attitude compensation, the measurement accuracy can reach 0.1 degrees, and it has good wave following and stability.

Furthermore, the floating ball contains a long-distance wireless transmission device, which can transmit the profile data back to the shore control room in real time and save it to the local database; the profile platform is composed of a sensor module, a data transfer center, and a battery compartment power supply module, which can The profile temperature and salt data are continuously and stably provided for a long time; the profile mechanical structure and the steel cable can select any observation depth within 0 to 500 meters, and the vertical observation resolution is about 3 cm.

Further, the deployment rules of the wave energy profile buoy observation array are: along the airborne route direction, according to the ku/ka dual-frequency synthetic aperture radar altimeter load sampling resolution interval.

A method for observing and calibrating sea surface height in deep seas based on large unmanned aerial vehicles. The method includes the following steps:

S1: Construct a high-precision deep sea sea surface height observation network, including shore-based GNSS reference stations, GNSS integrated observation buoy systems and wave energy profile buoy observation arrays to obtain sea surface height observation data sets in the same time and space as airborne altimeters;

S2: Offshore GNSS integrated observation buoy calculation: Combine the GNSS base station and offshore GNSS integrated observation buoy to calculate the offshore high-precision sea surface height reference point SSH ^GNSS ;

S3: Extrapolate to obtain the high-precision sea surface height SSH ₁ ^GNSS at adjacent wave energy profile buoy points, and construct a high-precision sea surface height calibration reference data set synchronized with the airborne route {SSH _i ^GNSS }: Utilize the wave energy profile buoy array The onboard sensor module observes elements to invert the sea surface height, that is, first inverts the sea surface height value SSH ₀ based on the barometer-profile CTD instrument-pressure gauge carried by the first wave energy profile buoy, and then calculates the difference between SSH ₀ and the adjacent The sea surface height difference Δ of the wave energy profile buoy SSH ₁ is finally combined with the high-precision sea surface height reference point SSH ^GNSS to extrapolate the high-precision sea surface height SSH ₁ ^GNSS of the adjacent wave energy profile buoy point; repeat continuously, that is, construct High-precision sea surface height calibration reference data set {SSH _i ^GNSS } synchronized with airborne routes;

S4: Calculate the calibration error value ΔE _i : based on the body height H _i ^GNSS obtained by the large UAV, the payload observation height ΔL _i , and the joint solution of the high-precision sea surface height calibration reference data set {SSH _i ^GNSS } Calculate the calibration error value ΔE _i ;

S5: Calibration inspection: Calculate the calibration error value ΔE _i along the observation trajectory of the airborne Ku/Ka dual-frequency synthetic aperture radar altimeter, and construct the calibration inspection of the deep sea sea surface height of the airborne Ku/Ka dual-frequency synthetic aperture radar altimeter. method.

Further, the S2 is specifically:

S2-1: GNSS base station data processing: During the aviation flight test, the shore data center uses Bernese or GAMIT software to solve the real-time base station data. During the solving process, the original data of the IGS station and the IGS of the adjacent ocean station need to be introduced. Post-processing products from analytical centers;

S2-2: Calculate SSH ^GNSS : The solution strategy uses the RTK positioning method, as follows: first, use the reception time difference between the GPS sea surface reflection signal and the direct signal arrival to calculate the distance difference to achieve the measurement of sea surface height; secondly, based on the GNSS double-difference positioning model Eliminate the receiver clock error and unknown parameters of the satellite clock. Consider the correction of the phase center position deviation of the receiver and satellite antenna during the processing. At the same time, a dual-frequency ionosphere-free combination method is selected to eliminate the refraction influence of the first-order term of the ionosphere, and Kalman is used. The filtering method estimates parameters epoch by epoch to obtain the coordinate difference between the offshore GNSS integrated observation buoy and the shore reference station, and finally obtains the 1HZ sea surface height of the offshore GNSS integrated observation buoy to provide instant reference values for aircraft navigation tests.

Further, the S3 is specifically:

S3-1: Calculate SSH ₀ : In the wave energy profile buoy array, the first buoy is deployed close to the offshore GNSS integrated observation buoy, so the CTD instrument carried by the wave energy profile buoy can efficiently collect this point. Vertical profiles of seawater temperature and conductivity; when the profile data is transmitted back to the data center through the nearshore wireless transmission network, it will be processed to remove the peak value of salinity and adjust the lagging sensor response. Finally, the hydrostatic The mechanical equation is integrated from the sea bottom to the sea surface to calculate SSH _0. The specific calculation formula is as follows:

in, Represents the integration result from the sea bottom to the sea surface, H represents the sea bottom depth, g represents the gravity acceleration,/> represents the average density of seawater, ρ ₀ represents the reference density,/> Represents the average sea surface height,/> Represents the average atmospheric pressure; in the equation/> Represents the bottom pressure at the buoy point, which needs to be measured by the bottom pressure gauge (BPR);/> Represents the dynamic height of the buoy point, which needs to be provided by a mooring device with CTD;/> Represents the atmospheric pressure at the buoy point, which is provided by the barometer on the buoy;

S3-2: Calculate SSH ₁ : Use formula (1) to calculate the sea surface height of the second buoy point in the wave energy profile buoy array;

S3-3: Calculate SSH ₁ ^GNSS : First, compare SSH ₀ and SSH ₁ to calculate the relative sea surface height difference Δ, use the difference between the two to eliminate the CTD-derived spatial height error, and secondly, calculate the near-shore high-precision full-depth stereo height SSH ^GNSS and the relative sea surface height difference Δ are jointly calculated to calculate SSH ₁ ^GNSS , ultimately achieving high-precision extrapolation of sea surface height;

S3-4: Repeat the above steps along the navigation route of the large UAV until all buoy points are calculated, and a high-precision sea surface height calibration reference data set {SSH _i ^GNSS } synchronized with the airborne route is constructed.

Further, the S4 is specifically:

S4-1: Obtain the flight altitude {H _i ^GNSS } of the aircraft based on the GNSS antenna mounted on the large UAV, and observe the altitude data set {(ΔL _i } based on the aircraft radar altimeter load;

S4-2: Calculate the verification error value ΔE _i from the combined airframe height data set {H _i ^GNSS }, payload observation height data set {ΔL _i }, and sea surface height calibration reference data set {SSH _i ^GNSS }. The calculation formula is as follows :

Further, the S5 is specifically:

S5-1: Obtain the actual observation data set of the airborne Ku/Ka dual-frequency synthetic aperture radar altimeter along the aircraft flight route, and continuously repeat S4 to calculate the corresponding calibration error value ΔE _i ;

S5-2: Calibrate the altitude data observed by the airborne radar altimeter using the calibration error value ΔE _i in order to improve the accuracy of the calibration results of the airborne altimeter load in the deep sea area.

Advantages and beneficial effects of the present invention:

On the basis of retaining the shore-based GNSS reference station, the present invention introduces offshore GNSS integrated observation buoys and wave energy profile buoy arrays to construct a high-precision sea surface height calibration inspection network in the deep sea. And based on the barometer-profile CTD instrument-bottom pressure gauge mounted on the wave energy profile buoy array and the GNSS module on the large unmanned aerial vehicle, a high-precision deep sea calibration inspection system is constructed to calibrate the Ku/Ka dual-frequency synthetic aperture radar altimeter. It provides accurate error calibration values and solves the problem of reduced calibration and inspection accuracy of traditional tide gauges/GNSS reference stations-GNSS buoy array observation solutions in far-reaching sea areas.

Compared with the traditional airborne altimeter calibration and inspection scheme, the present invention can effectively improve the accuracy of the calibration and inspection of deep seas, provide more precise calibration values for the calibration and inspection of the airborne altimeter, and achieve three-dimensional high spatial and temporal resolution of the ocean. authenticity test.

Description of the drawings

Figure 1 is a basic flow chart of the method provided by the present invention.

Figure 2 is a basic schematic diagram of the system provided by the present invention.

Figure 3 Wave energy profile buoy data collection results.

Detailed ways

The present invention will be further explained and described below through specific embodiments in conjunction with the accompanying drawings.

Example 1:

As shown in Figure 1, this embodiment proposes a high-precision deep-sea sea surface height observation and calibration method for simultaneous air-sea observation, specifically as follows:

1. Construct a simultaneous and spatial sea surface height observation data set.

The sea surface height observation network is shown in Figure 2. It consists of nearshore GNSS base stations, offshore (~20km) GNSS integrated observation buoys and wave energy profile buoy arrays, including:

(1) Establish shore-based GNSS reference stations and deploy offshore GNSS integrated observation buoys. The GNSS integrated observation buoy consists of an upper floating body (including data acquisition module), GNSS antenna, CTD profiler and bottom pressure gauge. The data acquisition module consists of GNSS receiver board, attitude compensator and wireless transmission module. Among them, the attitude compensator can accurately and efficiently output buoy attitude data at a frequency of 50HZ, ensuring the effectiveness of instantaneous buoy height measurement data in harsh marine environments, and the measurement accuracy can reach 0.1 degrees.

(2) Lay out wave energy profile buoy arrays. The wave energy profile buoy consists of an upper float, a profile platform, a crawling steel cable and a bottom pressure gauge. The upper float contains a long-distance wireless transmission device, which can transmit profile data back to the shore-based control room in real time and save it to a local database; profile The platform consists of a sensor module, a data transfer center, and a battery compartment power supply module, which can continuously and stably provide profile temperature and salt data for a long time.

(3) Construct a high-precision deep-sea sea surface height observation network. Shore-based GNSS reference stations, offshore GNSS integrated observation buoys and wave energy profile buoy arrays form a high-precision deep-sea sea surface height observation network. Among them, the wave energy profile buoy array is along the airborne route direction, based on the ku/ka dual-frequency synthetic aperture radar. The altimeter load sampling resolution intervals are arranged in a straight line to construct a high-precision sea surface observation data set that is simultaneous and spatial with the airborne altimeter data set.

2. Realize the calculation of offshore GNSS integrated observation buoys. Combined with the GNSS base station and the offshore GNSS integrated observation buoy, the offshore high-precision sea surface height reference value SSH ^GNSS is calculated based on the RTK positioning method, specifically:

(1) GNSS base station data processing. During the aviation flight test, the shore data center uses Bernese or GAMIT software to solve the real-time base station data. During the solving process, the original data of the IGS station of the adjacent ocean station and the post-processing products of the IGS analysis center need to be introduced.

(2) Calculate sea surface height. The distance difference is calculated using the reception time difference between the GPS sea surface reflection signal and the direct signal arrival, and the sea surface height measurement of the GNSS integrated observation buoy is realized.

(3) Calculate the satellite positioning system error. Errors in satellite positioning come from both internal and external sources of the system. Aiming at different sources of errors, we first eliminate unknown parameters such as receiver clock error and satellite clock based on the GNSS double-difference positioning model. During the processing, corrections such as receiver and satellite antenna phase center position deviations are considered, and a dual-frequency ionosphere-free combination is selected. The method eliminates the refraction effect of the first-order term of the ionosphere. Secondly, since the tropospheric total delay (ZTD) includes two parts: wet component delay (ZWD) and hydrostatic delay (commonly known as dry component delay ZHD), the tropospheric total delay formula is as follows:

ZTD＝ZWD+ZHD (3)

Where ZHD can be obtained from the Elgeredl hydrostatic delay formula:

in the formula is the geographical latitude, h is the altitude of the measuring station (KM), and Ps is the surface air pressure in hPa. From this, the atmospheric moisture delay retrieved by GNSS can be obtained.

(4) Calculate the high-precision sea surface height reference value SSH ^GNSS . After the above error term correction, the coordinate difference between the offshore GNSS integrated observation buoy and the shore reference station can be obtained, and finally the high-precision sea surface height measurement value SSH ^GNSS provided by the offshore GNSS integrated observation buoy can be obtained.

3. Extrapolate the sea surface height (SSH ₁ ) through the SSH ^GNSS measured by the GNSS integrated observation buoy and the SSH ₀ measured by the synchronous wave energy profile buoy, specifically:

(1) Calculate SSH ₀ . In the wave energy profile buoy array, the first buoy is deployed close to the offshore GNSS integrated observation buoy. The CTD instrument carried by the wave energy profile buoy can efficiently collect the vertical profile of seawater temperature and conductivity at that point. ; When the profile data is transmitted back to the data center through the nearshore wireless transmission network, it will be processed to remove the peak value of salinity and adjust the lagging sensor response. Finally, it is calculated by integrating the hydrostatic equation from the sea bottom to the sea surface. Out SSH ₀ , the specific calculation formula is as follows:

Among them, the three terms of the equation respectively represent the bottom pressure, dynamic height of the buoy point, and the sea surface pressure and atmospheric pressure caused by the sea surface. They require a bottom pressure gauge (BPR), a mooring device with CTD, and a barometer respectively. to provide. In this solution, the wave energy profile buoy array can rely on its own sensor set (barometer - profile CTD instrument - bottom pressure gauge) to derive the equivalent full-depth three-dimensional sea surface height.

(2) Calculate SSH ₁ . In the same way, the equivalent full-depth three-dimensional sea surface height SSH ₁ of the second buoy point is derived based on the sensor set of the wave energy profile buoy itself (barometer-profile CTD instrument-pressure gauge).

(3) Calculate SSH ₁ ^GNSS . First, compare the three-dimensional sea surface height (SSH ₀ and SSH ₁ ) obtained in step a) and step b) to calculate the relative sea surface height difference Δ, and use the difference between the two to eliminate the spatial height error derived from CTD and so on. The calculation formula of Δ is:

Δ＝SSH ₁ -SSH ₀ (5)

Secondly, the nearshore high-precision full-depth stereoscopic height SSH ^GNSS and the relative sea surface height difference Δ are jointly calculated to calculate SSH ₁ ^GNSS to achieve high-precision sea surface height extrapolation. The calculation formula of SSH ₁ ^GNSS is:

(4) Repeat the above steps along the aircraft's navigation route until all buoy points are calculated, and construct a high-precision sea surface height calibration reference data set {SSH _i ^GNSS } synchronized with the airborne route;

4. Calculate the calibration error value ΔE _i along the aircraft flight route, specifically:

(1) Obtain the aircraft flight altitude data set {H _i ^GNSS } and the payload observation height data set {ΔL _i } through the GNSS antenna and airborne radar altimeter mounted on the large UAV respectively.

(2) Jointly solve the verification error value ΔE i using the sea surface height calibration reference data set {SSH _i ^GNSS }, the airframe height data set {H _i ^GNSS } and the airborne radar altimeter observation data set {ΔL _{i }} , and calculate The formula is as follows:

5. Realize the calibration inspection of airborne Ku/Ka dual-frequency synthetic aperture radar altimeter, specifically:

(1) Obtain the actual observation data set of the airborne Ku/Ka dual-frequency synthetic aperture radar altimeter along the aircraft flight route, and continuously repeat step 4) to calculate the corresponding calibration error value ΔE _i .

(2) The altitude data observed by the airborne radar altimeter is sequentially corrected based on the calibration error value ΔE _i to improve the accuracy of the calibration results of the airborne altimeter load in the deep sea area.

Embodiment 2: Application example

Based on Example 1, a sea-air three-dimensional observation network was deployed in the South China Sea. Figure 3 is the temperature profile data collected by the wave energy profile buoy at fixed points on April 17, 2023. After quantity control, 10 were obtained Complete profile; it can be seen from the figure that there is a large temperature difference between the sea surface and the seabed, with the maximum temperature difference reaching 10°C, and the thermocline is deep, with the upper depth being around 110m and the lower depth being between 150 and 180m; experiments have proven that waves The profile buoy measurement results are accurate and can help altimeter products complete quantitative analysis of inspection errors with high precision.

On the basis of the above embodiments, the present invention continues to describe in detail the technical features involved and the functions and effects of the technical features in the present invention, so as to help those skilled in the art fully understand the present invention. technical solutions and reproduce them.

Finally, although this specification is described in terms of implementations, not each implementation only contains an independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should take the specification as a whole and refer to each implementation. The technical solutions in the examples can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

Claims (6)

1. A deep-sea sea surface height observation and calibration method based on a large UAV, characterized in that the method includes the following steps: S1: Construct a high-precision deep sea sea surface height observation network, including shore-based GNSS reference stations, GNSS integrated observation buoy systems and wave energy profile buoy observation arrays, to obtain sea surface height observation data sets in the same time and space as airborne altimeters; the GNSS The integrated observation buoy system consists of an upper buoy, a GNSS antenna, a CTD profiler and a bottom pressure gauge, and is deployed offshore; the wave energy profile buoy observation array includes multiple wave energy profile buoys, and the wave energy profile buoys are composed of an upper buoy Composed of ball, profile platform, crawling steel cable and bottom pressure gauge; S2: Offshore GNSS integrated observation buoy calculation: Combine the GNSS base station and offshore GNSS integrated observation buoy to calculate the offshore high-precision sea surface height reference point SSH ^GNSS ; S3: Extrapolate to obtain the high-precision sea surface height SSH ₁ ^GNSS at adjacent wave energy profile buoy points, and construct a high-precision sea surface height calibration reference data set synchronized with the airborne route {SSH _i ^GNSS }: Utilize the wave energy profile buoy array The mounted sensor module observes elements to invert the sea surface height, that is, first inverts the sea surface height value SSH ₀ based on the barometer-CTD profiler-pressure gauge carried by the first wave energy profile buoy, and secondly calculates the difference between SSH ₀ and the adjacent The sea surface height difference Δ of the wave energy profile buoy SSH ₁ is finally combined with the high-precision sea surface height reference point SSH ^GNSS to extrapolate the high-precision sea surface height SSH ₁ ^GNSS of the adjacent wave energy profile buoy point; repeat continuously, that is, construct High-precision sea surface height calibration reference data set {SSH _i ^GNSS } synchronized with airborne routes; S4: Calculate the calibration error value ΔE _i : based on the body height H _i ^GNSS obtained by the large UAV, the payload observation height ΔL _i , and the joint solution of the high-precision sea surface height calibration reference data set {SSH _i ^GNSS } Calculate the calibration error value; S5: Calibration inspection: Calculate the calibration error value sequentially along the observation trajectory of the airborne Ku/Ka dual-frequency synthetic aperture radar altimeter, and construct a calibration inspection method for the deep sea sea surface altitude of the airborne Ku/Ka dual-frequency synthetic aperture radar altimeter. 2. The deep sea sea surface height observation and calibration method based on large UAVs as claimed in claim 1, characterized in that the S2 is specifically: S2-1: GNSS base station data processing: During the aviation flight test, the shore data center will solve the real-time base station data, and introduce the original data of the IGS station of the adjacent ocean station and the processed product of the IGS analysis center during the solving process. ; S2-2: Calculate SSH ^GNSS : The solution strategy uses the RTK positioning method. 3. The deep sea sea surface height observation and calibration method based on large unmanned aerial vehicle as claimed in claim 2, characterized in that the S2-2 is as follows: first, the reception time difference between the GPS sea surface reflection signal and the direct signal arrival is used. To calculate the distance difference and achieve the measurement of sea surface height; secondly, based on the GNSS double-difference positioning model, the receiver clock difference and unknown parameters of the satellite clock are eliminated. During the processing process, the receiver and satellite antenna phase center position deviation correction is considered, and dual-frequency wireless is selected. The ionospheric combination method eliminates the refraction effect of the first-order term of the ionosphere, and uses the Kalman filter method to estimate parameters epoch by epoch to obtain the coordinate difference between the offshore GNSS integrated observation buoy and the shore base station, and finally use 1HZ sampling Frequency acquisition of the sea surface height of offshore GNSS integrated observation buoys provides instant reference values for aircraft navigation tests. 4. The deep-sea sea surface height observation and calibration method based on large UAVs as claimed in claim 1, characterized in that the S3 is specifically: S3-1: Calculate SSH ₀ : In the wave energy profile buoy array, the first buoy is deployed close to the offshore GNSS integrated observation buoy, so this point can be collected efficiently using the CTD profiler carried by the wave energy profile buoy. Vertical profiles of seawater temperature and conductivity at different locations; when the profile data is transmitted back to the data center via the nearshore wireless transmission network, the data will be processed to remove the peak value of salinity and adjust the lagging sensor response. Finally, the fluid The static equation is integrated from the sea bottom to the sea surface to calculate SSH _0. The specific calculation formula is as follows: in, represents the integration result from the sea bottom to the sea surface, H represents the sea bottom depth, g represents the gravity acceleration, represents the average density of seawater, ρ ₀ represents the reference density,/> Represents the average sea surface height,/> Represents the average atmospheric pressure; in the equation/> Represents the bottom pressure at the buoy point, which needs to be measured by the bottom pressure gauge BPR; Represents the dynamic height of the buoy point, which needs to be provided by a mooring device with a CTD profiler; S3-2: Calculate SSH ₁ : Use formula (1) to calculate the sea surface height of the second buoy point in the wave energy profile buoy array; S3-3: Calculate SSH ₁ ^GNSS : First, compare SSH ₀ and SSH ₁ to calculate the relative sea surface height difference, use the difference between the two to eliminate the spatial height error derived from the CTD profiler, and secondly use the offshore high-precision sea surface height reference point SSH ^GNSS and the relative sea surface height difference are jointly calculated to calculate SSH ₁ ^GNSS , ultimately achieving high-precision sea surface height extrapolation; S3-4: Repeat the above steps along the navigation route of the large UAV until all buoy points are calculated, and a high-precision sea surface height calibration reference data set {SSH _i ^GNSS } synchronized with the airborne route is constructed. 5. The deep sea sea surface height observation and calibration method based on large UAVs as claimed in claim 1, characterized in that the S4 is specifically: S4-1: Obtain the fuselage height data set {H _i ^GNSS } based on the GNSS antenna mounted on the large UAV, and observe the height data set {ΔL _i } based on the aircraft radar altimeter payload; S4-2: Calculate the verification error value of the joint airframe height data set {H _i ^GNSS }, payload observation height data set, and sea surface height calibration reference data set {SSH _i ^GNSS }. The calculation formula is as follows: 6. The deep sea sea surface height observation and calibration method based on large UAVs as claimed in claim 1, characterized in that the S5 is specifically: S5-1: Obtain the actual observation data set of the airborne Ku/Ka dual-frequency synthetic aperture radar altimeter along the aircraft flight route, and continuously repeat S4 to calculate the corresponding calibration error value; S5-2: Calibrate the altitude data observed by the airborne radar altimeter sequentially based on the calibration error value to improve the accuracy of the calibration results of the airborne altimeter load in the deep sea area.