Terahertz ice cloud imager

Abstract

The invention provides a terahertz ice cloud imager. The terahertz ice cloud imager comprises an interface mounting plate fixedly connected with a satellite; one end of the inner cylinder is fixed in the center of the interface mounting plate; the outer cylinder is sleeved outside the inner cylinder; the reflecting surface mounting plate is fixed on the outer side surface of the outer cylinder; the plurality of reflecting surfaces are fixed on the reflecting surface mounting plate; the heat preservation cylinder is fixed on the inner cylinder; the feed source mounting rack is fixed on the outer side surface of the part, positioned in the heat preservation cylinder, of the outer cylinder; the plurality of feed sources are fixed on the feed source mounting rack; the position of each feed source is opposite to a reflecting surface with the same frequency and polarization direction; each feed source is electrically connected with one or more receivers; the cold air reflecting surface and the calibration black body are fixed on the thermal insulation cylinder; the motor is fixed on the outer side surface of the inner cylinder and used for driving the outer cylinder, the reflecting surface and the feed source to rotate; and the slip ring is fixed on the inner cylinder and is used for supplying power and transmitting data to the outside. The antenna has the advantages that the number of channels is large, and the frequency band range is large; ground resolution ratios of 22 channels of 6 frequency bands are completely consistent.

Description

Technical Field

[0001] This application belongs to the fields of atmospheric science and remote sensing technology, and specifically relates to a terahertz ice cloud imager. Background Technology

[0002] Ice clouds reflect both shortwave solar radiation and longwave radiation from the ground, while simultaneously emitting thermal radiation outwards, significantly influencing the radiation balance of the Earth-atmosphere system. Deep convective ice clouds are also associated with short-duration, intense weather events such as heavy precipitation. Therefore, ice clouds are of great significance in climate research and weather forecasting.

[0003] Traditional remote sensing methods have their limitations in studying ice cloud orientation: visible light and infrared remote sensing have weak penetration and are only suitable for optically thin clouds with small particles; microwave remote sensing is mainly for large precipitation particles; active remote sensing, while having high vertical resolution, has a limited horizontal scanning range, making it difficult to achieve wide-swath imaging. To gain a more comprehensive understanding of the microphysical properties of ice clouds, new detection technologies need to be developed. Spaceborne terahertz (THz) radiometers, sensitive to non-precipitating ice crystals, offer global coverage, low power consumption, and all-weather detection capabilities, effectively compensating for the shortcomings of traditional remote sensing methods.

[0004] The only existing spaceborne THz ice cloud imager solution is the ICI (Ice Cloud Imager) of the European next-generation meteorological satellite Metop-SG-B series. It employs a conical scanning scheme with a common reflector and is mounted on the bottom of the satellite. The ICI includes 11 frequencies (see Table 1) and 13 channels. It uses a reflector antenna of approximately 50cm (see Table 1). Figure 1 ), reflecting THz radiation into 7 feed sources (see Figure 1 The scanning swath width is 1700 km, the scanning speed is approximately 27 rpm, the incident angle is approximately 53°, and the ground resolution is approximately 16 km. Due to the use of a single reflector, its feed design is very complex, employing a compact cluster of feed sources to receive signals from different frequency bands. This results in variations in ground spatial location and incident angle for different frequency bands (see...). Figure 2 The differences between the load and the antenna pattern affect the performance of the load.

[0005] Table 1 Main Technical Indicators of ICI Summary of the Invention

[0006] The purpose of this application is to overcome the shortcomings of existing technologies where differences in ground spatial location, incident angle, and antenna pattern across different frequency bands affect load performance.

[0007] To achieve the above objectives, this application proposes a terahertz ice cloud imager, comprising: A plate-shaped interface mounting plate is used for fixed connection with the satellite; The inner cylinder is cylindrical, with one end fixed to the center of the interface mounting plate; A hollow cylindrical outer cylinder is fitted around the outer side of the inner cylinder and is coaxial with the inner cylinder; the outer cylinder can rotate relative to the inner cylinder. An annular reflective mounting plate is fixed to one end of the outer side of the outer cylinder near the interface mounting plate; Multiple cylindrical reflective surfaces are fixed on the side opposite to the reflective surface mounting plate and the interface mounting plate; A hollow cylindrical heat-insulating cylinder is fixed at one end of the inner cylinder opposite to the reflective surface mounting plate; the axis of the heat-insulating cylinder coincides with the axis of the inner cylinder; part of the outer cylinder is located inside the heat-insulating cylinder; A ring-shaped feed mounting bracket is fixed to the outer side of the portion of the outer cylinder located inside the insulation cylinder; Multiple feed sources are fixed to the end face of the feed source mounting bracket adjacent to the reflector mounting plate; each feed source is positioned directly opposite a reflector with the same frequency and polarization direction; each feed source is electrically connected to one or more receivers. The cold air reflector and the calibration blackbody are fixed on the end face of the insulation cylinder adjacent to the reflector mounting plate; A motor is fixed to the outer side of the inner cylinder inside the insulation cylinder and is used to drive the outer cylinder to rotate; when the outer cylinder rotates, it drives the feed mounting bracket and the reflector mounting bracket to rotate together. A slip ring, fixed to the end of the inner cylinder away from the reflective mounting plate, is used to receive external power to power the motor and receiver, and also to transmit the data received by the receiver to the outside.

[0008] As an improvement to the aforementioned terahertz ice cloud imager, the center of the line of sight of the plurality of reflective surfaces is on a concentric circle, and the center of the concentric circle is the center of the ring of the reflective surface mounting plate. When multiple reflective surfaces are arranged, their centers of mass are balanced, and a set distance is maintained between them to ensure overall mass uniformity.

[0009] As an improvement to the aforementioned terahertz ice cloud imager, the number of reflective surfaces is eight, namely a 183GHz H-polarized reflective surface, a 243GHz V+H-polarized reflective surface, a 380GHz H-polarized reflective surface, a 424GHz H-polarized reflective surface, a 664GHz H-polarized reflective surface, a 664GHz V-polarized reflective surface, an 874GHz H-polarized reflective surface, and an 874GHz V-polarized reflective surface.

[0010] As an improvement to the aforementioned terahertz ice cloud imager, the number of feed sources is eight, namely a 183GHz H-polarized feed source, a 243GHz V+H-polarized feed source, a 380GHz H-polarized feed source, a 424GHz H-polarized feed source, a 664GHz H-polarized feed source, a 664GHz V-polarized feed source, an 874GHz H-polarized feed source, and an 874GHz V-polarized feed source.

[0011] As an improvement to the aforementioned terahertz ice cloud imager, the 183 GHz H-polarized feed is electrically connected to the 183.31±7 GHz H-polarized receiver, the 183.31±4.5 GHz H-polarized receiver, the 183.31±3 GHz H-polarized receiver, the 183.31±1.8 GHz H-polarized receiver, and the 183.31±1 GHz H-polarized receiver. The 243GHz V+H polarization feed is electrically connected to the 243.25±2.5GHz V polarization receiver and the 243.25±2.5GHz H polarization receiver. The 380GHz H-polarized feed is electrically connected to the 380.2±18.0GHz H-polarized receiver, the 380.2±9.0GHz H-polarized receiver, the 380.2±4.0GHz H-polarized receiver, the 380.2±1.5GHz H-polarized receiver, and the 380.2±0.4GHz H-polarized receiver. The 424GHz H-polarized feed is electrically connected to the 424.7631±15.24GHz H-polarized receiver, the 424.7631±4.0GHz H-polarized receiver, the 424.7631±1.5GHz H-polarized receiver, the 424.7631±1.0GHz H-polarized receiver, the 424.7631±0.6GHz H-polarized receiver, and the 424.7631±0.3GHz H-polarized receiver. The 664GHz H-polarized feed is electrically connected to the 664.0±4.2GHz H-polarized receiver; The 664GHz V-polarized feed is electrically connected to the 664.0±4.2GHz V-polarized receiver; The 874GHz H-polarized feed is electrically connected to the 874.0±4.2GHz H-polarized receiver; The 874 GHz V-polarized feed is electrically connected to the 874.0 ± 4.2 GHz V-polarized receiver.

[0012] As an improvement to the aforementioned terahertz ice cloud imager, the cold air reflector and the calibration blackbody are installed close to each other, or on opposite sides of the satellite's direction of travel.

[0013] Compared with existing technologies, the advantages of this application are: The terahertz ice cloud imager provided in this application has multiple channels and a wide frequency range; it adopts a modular design, allowing for more rational optimization and configuration of frequency bands; the ground resolution of the 22 channels across 6 frequency bands is completely consistent; the antenna pattern has good symmetry, and the main beam efficiency and other technical indicators are higher; it can easily achieve forward and backward observation, improving the detection capability of ice clouds. Attached Figure Description

[0014] Figure 1 The diagram shows the structure of the ICI (Ice Cloud Imager) of the Metop-SG-B series of next-generation European weather satellites. Figure 2 The diagram shows the instantaneous ground footprint distribution of ICI. The seven footprints in the diagram represent pixels in seven frequency bands. Each footprint has two circles: the inner circle corresponds to the -3dB beam range, and the outer circle corresponds to the -6dB range. It is assumed that ICI is located at an orbital altitude of 824.5km, latitude 6.9°S, and longitude 175.3°E. Figure 3 The diagram shown is a structural diagram of the ice cloud imager provided in this application; Figure 4 The image shown is a longitudinal cross-sectional view of the ice cloud imager provided in this application; Figure 5 The image shown is a top view of the ice cloud imager provided in this application; Figure 6 The figure shown is a schematic diagram of the dimensions of the ice cloud imager provided in this application; Figure 7(a) shows the antenna radiation patterns in two sections (height and azimuth) of the 183.31 GHz band; Figure 7(b) shows the antenna radiation patterns in two sections (height and azimuth) of the 243.25 GHz band; Figure 7(c) shows the antenna radiation patterns in two sections (height and azimuth) of the 380 GHz band; Figure 7(d) shows the antenna radiation patterns in two sections (height and azimuth) of the 424.76 GHz band; Figure 7(e) shows the antenna radiation patterns in two sections (height and azimuth) of the 664 GHz band; Figure 7(f) shows the antenna radiation patterns in two sections (height and azimuth) of the 874 GHz band; Figure 8(a) shows the total information content of the ice cloud imager channel provided in this application; Figure 8(b) shows the total information content of the ICI channel; Figure 9 The figure shows the difference between the ice cloud imager provided in this application and the information content of the ICI channel. Detailed Implementation

[0015] The technical solution of this application will be described in detail below with reference to the accompanying drawings.

[0016] The terahertz ice cloud imager provided in this application has the following functions: 1. Implement the functions of scanning, room temperature calibration, and cold air calibration of the THz ice cloud imager in accordance with the established technical specifications and working mode requirements; 2. Under a given working environment, it possesses sufficient strength, rigidity, and reliability; 3. Equipped with a rotating conductive slip ring; capable of bidirectional transmission of relevant data, control signals and power signals of the rotating scanning device; capable of real-time communication with the rotating scanning device and transmitting back system operating status information.

[0017] like Figures 3-6 As shown, the terahertz ice cloud imager provided in this application is a real-aperture submillimeter radiometer with a fixed incident angle, mechanical conical scanning, multi-reflector antenna, multi-feed horn, multi-frequency multi-channel full-power reception, and on-orbit periodic two-point calibration.

[0018] The terahertz ice cloud imager provided in this application includes a plate-shaped interface mounting plate 1 for fixed connection with the satellite. A cylindrical inner cylinder 10 is fixed to the center of the interface mounting plate 1 in a direction perpendicular to the plane of the interface mounting plate 1. A cylindrical outer cylinder 4 is fitted around the outer side of the inner cylinder 10. The outer cylinder 4 is coaxial with the inner cylinder 10. The outer cylinder 4 can rotate relative to the inner cylinder 10. An annular reflector mounting plate 2 is fixed to one end of the outer side of the outer cylinder 4 near the interface mounting plate 1. Eight cylindrical reflectors 3 are fixed to the reflector mounting plate 2 on the side opposite to the interface mounting plate 1.

[0019] The eight reflectors 3 are H-polarized reflectors at 183 GHz, V+H-polarized reflectors at 243 GHz, H-polarized reflectors at 380 GHz, H-polarized reflectors at 424 GHz, H-polarized reflectors at 664 GHz, V-polarized reflectors at 664 GHz, H-polarized reflectors at 874 GHz, and V-polarized reflectors at 874 GHz. The line-of-sight centers of the eight reflectors 3 lie on a concentric circle, and the center of this concentric circle is the center of the reflector mounting plate 2. The arrangement of the eight reflectors 3 requires centroid balance, maintaining a certain distance between them to ensure overall mass uniformity and reduce disturbances in scanning inertia.

[0020] A hollow cylindrical insulation cylinder 7 is fixed to one end of the inner cylinder 10 opposite to the reflector mounting plate 2. The axis of the insulation cylinder 7 coincides with the axis of the inner cylinder 10. Part of the outer cylinder 10 is located inside the insulation cylinder 7. An annular feed mounting bracket 11 is fixed to the outer side of the outer cylinder 10 located inside the insulation cylinder 7.

[0021] Eight feeds (not shown in the figure) are installed on the end face adjacent to the feed mounting bracket 11 and the reflector mounting plate 2. The eight feeds are positioned directly opposite eight reflectors 3 with the same frequency and polarization direction. The eight feeds are a 183GHz H-polarized feed, a 243GHz V+H-polarized feed, a 380GHz H-polarized feed, a 424GHz H-polarized feed, a 664GHz H-polarized feed, a 664GHz V-polarized feed, an 874GHz H-polarized feed, and an 874GHz V-polarized feed. Specifically, the 183GHz H-polarized feed is electrically connected to the 183.31±7GHz H-polarized receiver, the 183.31±4.5GHz H-polarized receiver, the 183.31±3GHz H-polarized receiver, the 183.31±1.8GHz H-polarized receiver, and the 183.31±1GHz H-polarized receiver; the 243GHz V+H-polarized feed is connected to the 243.25±2.5GHz V... The H-polarized receiver is electrically connected to the 243.25±2.5GHz H-polarized receiver; the 380GHz H-polarized feedhorn is electrically connected to the 380.2±18.0GHz H-polarized receiver, the 380.2±9.0GHz H-polarized receiver, the 380.2±4.0GHz H-polarized receiver, the 380.2±1.5GHz H-polarized receiver, and the 380.2±0.4GHz H-polarized receiver; 42 A 4 GHz H-polarized feedhorn with H-polarized receivers at 424.7631±15.24 GHz, 424.7631±4.0 GHz, 424.7631±1.5 GHz, 424.7631±1.0 GHz, 424.7631±0.6 GHz, and 424.7631±0.3 GHz. Electromechanical connections; 664GHz H-polarized feed and 664.0±4.2GHz H-polarized receiver are electrically connected; 664GHz V-polarized feed and 664.0±4.2GHz V-polarized receiver are electrically connected; 874GHz H-polarized feed and 874.0±4.2GHz H-polarized receiver are electrically connected; 874GHz V-polarized feed and 874.0±4.2GHz V-polarized receiver are electrically connected.

[0022] A cold-air reflector 5 and a calibration blackbody 6 are fixed on the end face adjacent to the reflector mounting plate 2. The cold-air reflector 5 and the calibration blackbody 6 can be installed close to each other or separately on both sides of the satellite's forward direction. When installed on both sides of the satellite's forward direction, in addition to calibration on both sides, forward and backward observations can be achieved during a single scan.

[0023] Inside the insulation cylinder 7, a slip ring 9 is fixed to the end of the inner cylinder 10 away from the reflector mounting plate 2. Inside the insulation cylinder 7, a motor 8 is also fixed to the outer surface of the inner cylinder 10. The motor 8 drives the outer cylinder 2 to rotate at a constant speed. When the outer cylinder 2 rotates, it causes the feed mount 11 and the reflector mount 2 to rotate together. In each scanning cycle, the cold-air reflector 5 and the calibration blackbody 6 respectively block eight feeds, achieving two-point calibration of the 22 radiometer channels at the feed aperture. The slip ring 9 is used to receive power from the satellite, powering the motor 8 and the 22 receivers, and also to transmit the data observed by the receivers to the satellite for storage and back to Earth.

[0024] In other embodiments, the number of feed sources and reflectors may be less than or more than eight, and can be increased or decreased according to observation requirements.

[0025] The channel design specifications of the terahertz ice cloud imager provided in this application are shown in Table 2. It includes six complete frequency bands from 183 to 874 GHz, comprising 22 channels. 424 GHz is used for atmospheric background temperature and ice cloud detection to improve the understanding of cloud physics processes involved in ice cloud formation. The bandwidth and sensitivity (NEDT) of the corresponding channels are also given in the table. Table 3 presents the main engineering parameters of the terahertz ice cloud imager.

[0026] Table 2 Channel Design Specifications for THz Ice Cloud Imager

[0027]

[0028] Table 3 Main Technical Specifications of the THz Ice Cloud Imager

[0029] The terahertz ice cloud imager provided in this application uses an antenna consisting of an offset parabolic reflector and a horn feed. To enable the six frequency bands to work together and reduce the difficulty and risk of engineering implementation, each independent reflector corresponds to a feed for an independent frequency band. All reflectors are arranged on the same outer contour, and all antennas are synchronously conical scanned by a single drive mechanism. According to the characteristics and accuracy requirements of each frequency band, the dual polarization of the low-frequency band uses an off-center polarization mechanism (OMT) to separate horizontal and vertical polarization. The high-frequency band uses two independent feeds of the same frequency band placed side by side to separate horizontal and vertical polarization. Therefore, the terahertz ice cloud imager system provided in this application covers six operating frequency bands, corresponding to eight discrete reflectors. The specific antenna polarization methods and their implementation methods are shown in Table 4.

[0030] Table 4 Antenna polarization methods and their implementation for the THz ice cloud imager

[0031] The terahertz ice cloud imager provided in this application has two operating states: (1) Storage status: The terahertz ice cloud imager is not powered on, environmental protection is in place, and it is left to stand still; (2) Normal observation state: The motor drives the outer cylinder, which in turn drives the feed, receiver, reflector, and reflector mounting plate to rotate continuously and uniformly in one direction at a speed of about 20~30 rpm.

[0032] The terahertz ice cloud imager provided in this application has an approximate outer envelope size of φ602mm × 698mm. Figure 6 As shown. The weight of the entire system is less than 100 kg.

[0033] Figures 7(a)-7(f) show the simulated antenna radiation patterns in two cross-sections (altitude and azimuth) for the six frequency bands. It can be seen that the antenna radiation patterns in all frequency bands are consistent and symmetrical. The main beam efficiency is ≥95% for all bands. This demonstrates that the design possesses excellent antenna characteristics.

[0034] The simulation results (see Table 5) show that the antenna beamwidth, beam efficiency, sidelobes, and cross-polarization all meet high requirements. Table 6 presents the simulation calculation results for the antenna parameters and spatial resolution. It is evident that at an incident angle of 53° and a sun-synchronous orbit altitude of 820 km, the above design can achieve a completely consistent spatial resolution of 16 km. The ground resolution can also be flexibly adjusted by changing the orbital altitude and antenna aperture. This is also an advantage of this scheme. Therefore, this can be used as a basis for the detailed design of the THz ice cloud imager system.

[0035] Table 5. Statistics of antenna performance simulation results for the THz ice cloud imager

[0036] Table 6 Comparison of antenna aperture and spatial resolution differences in different frequency bands of the THz ice cloud imager

[0037]

[0038] Through the design of Tables 2 and 3, the terahertz ice cloud imager provided in this application further enhances the detection capability of atmospheric cloud parameters. Information content analysis quantifies the information obtained from measurements of a specific channel; this information leads to a reduction in prior error: the more information, the greater the attenuation. Information can be quantified by calculating the degree-of-freedom attenuation compared to the prior state or by calculating the entropy S between the two states (e.g., Rodgers, 2011; Di Michele and Bauer, 2006). Here, the degree-of-freedom attenuation ΔDOF is used, defined as follows: in, I It is the identity matrix. S a The prior covariance matrix, S r Let be the posterior error covariance matrix. If the posterior error is the same as the prior error, then ΔDOF is zero and no information is obtained. The closer the posterior error is to zero, the greater the degrees of freedom. The maximum value (which is practically unattainable) is equal to the number of channels. Taking a mid-latitude spring scene in the Northern Hemisphere as an example, using the current channel configuration, the information content under 16 different hydrogel combinations was calculated using the ARTS model and compared with the information content of the ICI. The total information content of the instruments is shown in Figures 8(a) and 8(b), and the difference in information content between the two instruments is as follows: Figure 9 As shown in the figure, the terahertz ice cloud imager provided in this application has a significant effect on improving the amount of water vapor information compared to ICI. Regardless of the type of water condensate particle, the information content and average mass are improved, and the information content of the average mass is improved even more.

[0039] Figure 8(a), Figure 8(b) and Figure 9 In the horizontal axis, L, R, I, S, G, and H refer to liquid water particles, rain particles, ice cloud particles, snow particles, graupel particles, and hail particles, respectively. The 16 horizontal axes represent the profiles formed by different combinations of the six types of hydrophobic particles. For example, IS refers to the profile containing only ice cloud particles and snow particles. Additionally, V on the far right represents water vapor, indicating a clear sky profile containing only water vapor. Figures 8(a), 8(b), and... Figure 9 The vertical axis in the figure represents the degree of freedom attenuation ΔDOF, which quantifies the amount of information obtained from a specific channel measurement; the greater the attenuation, the more information is obtained. (Figures 8(a), 8(b), and...) Figure 9 The icons LWC, RWC, IWC, and SWC in the diagram represent the information content of liquid water particles, rain particles, ice cloud particles, and snow particles, respectively. mLWC, mRWC, mIWC, and mSWC represent the information content of the average mass of liquid water particles, rain particles, ice cloud particles, and snow particles, respectively. H2O represents the information content of water vapor.

[0040] Compared to ICI, the terahertz ice cloud imager provided in this application has more channels and a wider frequency range; it adopts a modular design, allowing for more rational optimization and configuration of frequency bands; the ground resolution of the 22 channels across 6 frequency bands is completely consistent; it has good antenna pattern symmetry and higher technical indicators such as main beam efficiency; it can easily achieve forward and backward observations, improving the detection capability of ice clouds.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application do not depart from the spirit and scope of the technical solutions of this application, and should all be covered within the scope of the claims of this application.

Claims

1. A terahertz ice cloud imager, characterized by, It comprises: a plate-shaped interface mounting plate for fixed connection with a satellite; a cylindrical inner cylinder with one end fixed at the center of the interface mounting plate; a hollow cylindrical outer cylinder sleeved outside the inner cylinder coaxially with the inner cylinder, the outer cylinder being rotatable relative to the inner cylinder; a ring-shaped reflector mounting plate fixed at one end of the outer cylinder outside surface close to the interface mounting plate; a plurality of columnar reflectors fixed at the side of the reflector mounting plate opposite to the interface mounting plate; a hollow cylindrical heat-insulating cylinder fixed at the end of the inner cylinder opposite to the reflector mounting plate, the axis of the heat-insulating cylinder coinciding with the axis of the inner cylinder, and part of the outer cylinder being located inside the heat-insulating cylinder; a ring-shaped feed mounting rack fixed at the outer surface of the outer cylinder inside the heat-insulating cylinder; a plurality of feeds fixed at the end surface of the feed mounting rack adjacent to the reflector mounting plate, each feed being opposite to one reflector with the same frequency and polarization direction, and each feed being electrically connected to one or more receivers; a cold space reflector and a calibration black body fixed at the end surface of the heat-insulating cylinder adjacent to the reflector mounting plate; a motor fixed at the outer surface of the inner cylinder inside the heat-insulating cylinder for driving the rotation of the outer cylinder, the outer cylinder rotating together with the feed mounting rack and the reflector mounting rack; and a slip ring fixed at the end of the inner cylinder away from the reflector mounting plate for receiving external power supply to power the motor and the receivers, and for transmitting data received by the receivers to the outside.

2. The terahertz ice cloud imager of claim 1, wherein, The boresight centers of the plurality of reflectors are on a concentric circle, and the center of the concentric circle is the center of the reflector mounting plate; The plurality of reflectors are arranged with balanced mass centers and kept at a set distance from each other to balance the overall mass.

3. The terahertz ice cloud imager of claim 1, wherein, The number of the reflectors is eight, including H-polarized reflectors of 183 GHz, V+H-polarized reflectors of 243 GHz, H-polarized reflectors of 380 GHz, H-polarized reflectors of 424 GHz, H-polarized reflectors of 664 GHz, V-polarized reflectors of 664 GHz, H-polarized reflectors of 874 GHz, and V-polarized reflectors of 874 GHz.

4. The terahertz ice cloud imager of claim 1, wherein, The number of the feeds is eight, including H-polarized feeds of 183 GHz, V+H-polarized feeds of 243 GHz, H-polarized feeds of 380 GHz, H-polarized feeds of 424 GHz, H-polarized feeds of 664 GHz, V-polarized feeds of 664 GHz, H-polarized feeds of 874 GHz, and V-polarized feeds of 874 GHz.

5. The terahertz ice cloud imager according to claim 4, wherein: the H-polarized feed of 183 GHz is electrically connected to H-polarized receivers of 183.31±7 GHz, H-polarized receivers of 183.31±4.5 GHz, H-polarized receivers of 183.31±3 GHz, H-polarized receivers of 183.31±1.8 GHz, and H-polarized receivers of 183.31±1 GHz. The 243GHz V+H polarized feed is electrically connected with a 243.25±2.5GHz V polarized receiver and a 243.25±2.5GHz H polarized receiver; The 380GHz H polarized feed is electrically connected with a 380.2±18.0GHz H polarized receiver, a 380.2±9.0GHz H polarized receiver, a 380.2±4.0GHz H polarized receiver, a 380.2±1.5GHz H polarized receiver and a 380.2±0.4GHz H polarized receiver; The 424GHz H polarized feed is electrically connected with a 424.7631±15.24GHz H polarized receiver, a 424.7631±4.0GHz H polarized receiver, a 424.7631±1.5GHz H polarized receiver, a 424.7631±1.0GHz H polarized receiver, a 424.7631±0.6GHz H polarized receiver and a 424.7631±0.3GHz H polarized receiver; The 664GHz H polarized feed is electrically connected with a 664.0±4.2GHz H polarized receiver; The 664GHz V polarized feed is electrically connected with a 664.0±4.2GHz V polarized receiver; The 874GHz H polarized feed is electrically connected with a 874.0±4.2GHz H polarized receiver; The 874GHz V polarized feed is electrically connected with a 874.0±4.2GHz V polarized receiver.

6. The terahertz ice cloud imager of claim 1, wherein, The cold space reflector and the calibration black body are installed close to each other, or are installed on the two sides of the satellite in the forward direction respectively.

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