Hyperspectral microwave radiometer is a new type of passive microwave remote sensor for observing middle and upper atmospheric temperature, humidity, trace gas, and other parameters such as winds. The digital spectrometer, which allows the fine sampling of the spectral lines, is the core component of the radiometer. In this article, we propose the design and implementation of a new type of wideband, real-time channelized digital spectrometer, which realizes the core base-64 real-time complex fast Fourier transform (FFT) algorithm and channelization algorithm by improving the filter bank, 128-channel parallel processing of FFT and complex number processing. The digital spectrometer has a sampling rate of 20 Gsps, a quantization bit number of 8 bits, and an input bandwidth of 10 GHz, which realizes the spectrum analysis of 4096 channels. Then, an observation test was carried out using a V-band ground-based microwave radiometer equipped with the 10-GHz spectrometer, and the atmospheric temperature profile was successfully measured from the surface to the stratosphere. The retrieval results were compared with the ERA5 reanalysis data and the L2 temperature products of the FY-3-D/MWTS-MWHS and Aura/microwave limb sounder (MLS), with a better consistency, which proved the application and potential of the new wideband digital spectrometer in the atmospheric sounding.
This paper explores the performance advantages of spaceborne hyperspectral microwave radiometers for jointly retrieving atmospheric temperature and humidity profiles under clear-sky conditions. It utilizes 4,440 channels at a spectral resolution of 10 MHz and 444 channels at a spectral resolution of 100 MHz across the 60 GHz, 118 GHz, and 183 GHz bands. The Atmospheric Radiative Transfer Simulator (ARTS) was employed as the forward model to generate virtual high-spectral-resolution observational data, based on 10,745 marine profiles from the ECMWF-137 dataset. Channel selection eliminated about half of the channels with spectral resolutions of both 10 MHz and of 100 MHz while retaining 90$\% $% of the information content. The iterative retrieval model was constructed using the Optimal Estimation Method (OEM) for retrieval experiments, incorporating combinations of channels with 10 MHz and 100 MHz spectral resolutions, as well as those selected through an information entropy-based method and channels from MWTS (Micro-Wave Temperature Sounder) and MWHS (Micro-Wave Humidity Sounder), enabling high-accuracy retrieval of atmospheric temperature and humidity profiles. Specifically, the 10 MHz resolution extends the effective temperature sensing range from the surface to 70 km, with vertical resolution enhanced to 2-18 km for temperature and 1.6-6 km for humidity. Within the 0-35 km and 0-12 km altitude ranges, temperature retrieval errors are reduced by 0.5 K, and humidity retrieval errors are reduced by 0.00003 kg/kg for specific humidity and 2.4$\% $% for relative humidity, respectively. Theoretical analysis and quantitative retrieval demonstrate that hyperspectral microwave radiometer outperforms traditional MWTS + MWHS systems in terms of effective sensing range (temperature), vertical resolution, information content, and retrieval accuracy, while also highlighting the effectiveness of channel selection.
The scanning drive mechanism of the spaceborne microwave-sounding antenna has two working modes of constant speed and variable speed, and the special structural form and layout of the reflecting surface lead to a large perturbation moment in the constant speed and variable speed scanning modes. The optimized design of the reflecting surface reinforcement structure of the antenna’s scanning drive mechanism is of great significance for the adjustment of the dynamic stiffness and rotational moment of inertia of the system, which helps to reduce the influence of the moment perturbation. In this paper, a design method combining topology optimization and size optimization is adopted to optimize the design of the reflecting surface reinforcement structure of the planar antenna. The topology optimization constrains the volume, and the objective function is the first-order frequency maximum. The topology optimization results show that the reinforcement is arranged along the center in a “palm” shape. The size optimization is based on the objective of minimizing the rotational inertia of the structure, and the constraints are the dynamic stiffness and the RMS of the structural stress values. The dynamic stiffness of the structure is improved after size optimization, the mass of the reinforcing bar is reduced by 26% compared with the original structure, the rotational inertia of the planar antenna is reduced by 39% compared with the original structure, and the perturbation moments are decreased by 52% at uniform speeds and by 39% at variable speeds.
Microwave hyperspectral sounders are key instruments for next-generation meteorological satellites, designed to replace broadband sounders, such as advanced technology microwave sounder (ATMS), microwave temperature sounder (MWTS), and microwave humidity sounder (MWHS). A major challenge in their design is determining the optimal channel bandwidth configuration to maximize the use of absorption spectra and enhance vertical atmospheric profiling. This study evaluates two variable-bandwidth strategies: 1) a generalized variable-bandwidth approach, which applies multiple fixed bandwidth combinations across different frequency bands and 2) a dynamic bandwidth strategy, which differentiates channel bandwidths within the same frequency band for absorption peak and wing regions. The retrieval performance of various bandwidth configurations is analyzed for lower and upper atmospheric temperature and humidity observations. Results indicate that for upper atmosphere temperature retrievals, the 60- and 118-GHz bands achieve higher accuracy with a 10-MHz bandwidth. For lower atmosphere temperature retrievals, where most information originate from the O2 absorption line's wing region, a wider bandwidth reduces observation costs while maintaining comparable accuracy. Water vapor retrievals, which primarily rely on the 118-GHz wing region and 183-GHz absorption lines, show minimal sensitivity to bandwidth configurations. A novel channel configuration method is proposed, integrating both absorption peak and wing regions into a single-optimized scheme. Experimental results demonstrate that the $10+ 10+100$ MHz (peak) $+ 50+ 100+100$ MHz (wing) configuration achieves the best retrieval accuracy across different atmospheric layers, significantly improving both temperature and humidity profiling compared with existing broadband sounders. The advantages of using variable channel bandwidth hyperspectral microwave radiometers for joint retrieval of temperature and humidity profiles have been demonstrated from both theoretical analysis and quantitative retrieval optimal estimation method (OEM), providing theoretical support and technical guidance for the development of the next generation of spaceborne hyperspectral microwave radiometers.
This article investigates the potential of microwave sounders for a future international Venusian lower atmosphere exploration mission. Venusian microwave atmospheric radiative transfer (RT) calculations from a spaceborne perspective are performed with appropriate settings of the specific observation geometry and input atmospheric scenarios. An atmospheric profile perturbation analysis was undertaken to determine the channel selection and corresponding retrieval accuracy. Meanwhile, a suitable configuration of microwave sounder is proposed based on the gas absorption characteristics, sensitivity, and retrieval error analysis. The channel frequency selected includes 21 (2) channels of SO2 (H2SO4) absorption lines and its sidebands, as well as 37 channels between 6 and 42 GHz. Due to the strong coupling between temperature, SO2, and H2SO4 in the lower atmosphere, a joint physical retrieval method [optimal estimation method (OEM)] is proposed. Under ideal model conditions, the RMSE of retrieved temperature profiles improves by 1.3 K to stay within 2 K for 0-65 km, while the maximum RMSEs for SO2 and H2SO4 volume mixing ratios (VMRs) show improvements of at least 15% and 10%, reaching 30% and 25%, respectively. These results validate the proposed microwave sounder's effectiveness for temperature and SO2 (H2SO4) profiling up to 65 km (30-75 km for SO2 and 35-55 km for H2SO4). However, increasing model error reduces retrieval accuracy, emphasizing the importance of model development for accurate joint observations of these parameters.
Atmospheric boundary layer detection is in urgent demand in meteorological and climate research and is closely related to human life and agricultural production. Atmospheric microwave fine-spectral sounding is a cutting-edge means to break through the regional and even global all-weather atmospheric boundary layer temperature and humidity profiling observations. In this paper, we carry out field campaigns using a unmanned aerial vehicle-based (UAV-based) fine-spectral microwave radiometer to solve key technologies of boundary layer detection and inversion, and realize the sounding of atmospheric water condensate and the study of the evolution.
This paper conducts an in-depth analysis of spaceborne hyperspectral microwave radiometers for remotely sensing atmospheric boundary layers’ temperature and humidity profiles. Utilizing 137 vertical-level atmospheric profile data from the European Centre for Medium-Range Weather Forecasts (ECMWF), the study employs the Atmospheric Radiative Transfer Simulator (ARTS) to construct a forward model of an Earth-based spaceborne microwave radiometer, enabling the computation of the Jacobian matrix. This research thoroughly evaluates the posterior probability of retrieval errors and vertical resolution by analyzing both the background error covariance matrix and the measurement error covariance matrix alongside the Jacobian matrix. Findings reveal that a spectral resolution of 10 MHz significantly enhances the accuracy of posterior retrieval errors and improves vertical resolution, in contrast to the 1000 MHz resolution, which shows lesser efficacy. While hyperspectral microwave radiometers offer clear benefits for detailed atmospheric profiling, the increase in spectral resolution does not uniformly translate to performance enhancements due to the accompanying rise in system noise. These results underscore the importance of conducting meticulous assessments to determine the most effective spectral resolution for radiometers, considering the intricate balance between information gain and noise.
FengYun-3F (FY-3F) is a sun-synchronous satellite launched on August 3, 2023. It crosses the equator at a local time of 10:15 a.m. and will be a substitute for FY-3C. This study introduces the preflight and in-orbit calibration of microwave humidity sounder-II (MWHS-II) onboard FY-3F. The instrument nonlinearity and radiometric sensitivity are characterized in the ground thermal vacuum chamber (TVAC) tests. The residual of nonlinearity correction is within 0.5 K, depending on viewing scenes and channels. As a substitute for its predecessor FY-3C, the performance of MWHS-II onboard FY-3F is compliant with requirements. The in-orbit radiometric sensitivity of the sensor is consistent with the prediction of the TVAC test results, with margins of 20%-60% relative to the requirements. The in-orbit behavior of the sensor is further evaluated by simultaneous nadir overpass (SNO) with the advanced technology microwave sounder (ATMS) and the difference between observation-background (O-B). The results confirm that the radiometric performance of MWHS-II onboard FY-3F is improved, compared to FY-3C. With stable and consistent observations, MWHS-II onboard FY-3F will benefit numerical weather predictions by providing accurate temperature and humidity information at the 118- and 183-GHz bands.
Since the first microwave humidity sounder (MWHS) launched on May 27, 2008, six MWHSs deployed on polar-orbiting FengYun-3 (FY-3) satellites to date have been continuously providing temperature and humidity information for over 15 years. Compared to the predecessors MWHS onboard FY-3A/B/C/D, the central frequency of the window channel is shifted from 150 to 166 GHz for MWHS-II onboard FY-3E/F, and the additional low noise amplifier (LNA) embedded in the radio frequency (RF) module optimizes the performance of the receiver system, leading to a significant reduction in the noise temperature of the receivers. The reduced bias and standard deviation of simultaneous Nadir overpass (SNO) results between MWHS-II and Advanced Technology Microwave Sounder (ATMS) further corroborate that that the instrument performance has been improved and updated. The interchannel interference of FY-3E/F is mitigated, and the channel sensitivities are also enhanced according to the postlaunch test results.
Stratospheric ozone concentration has an important impact on global climate change and ecological environment.Hyperspectral millimeter wave radiometer with spectral analysis capability is a passive microwave remote sensor used to detect atmospheric trace gases.It can effectively detect the ver-tical profile of atmospheric ozone and has very important application value in the field of space earth sci-ence.In this paper,a new hyperspectral millimeter wave ozone radiometer system for detecting strato-spheric ozone absorption lines is developed.The system structure includes RF receiver and digital spec-trum analyzer.The RF receiver part uses a superheterodyne structure to obtain a 142.175 GHz±100 MHz bandwidth signal.The digital spectrum analysis part uses a high-performance analog-to-digital converter to sample the input analog signal at 5×108 sample·s-1.The quantization bit is 14 bit and the 3 dB band-width of the input signal is 200 MHz.The signal power spectrum is obtained by high-performance Field Programmable Gate Array(FPGA),and the number of detection channels is 16384,and the spectral res-olution reached 12.2 kHz.This paper introduces the design scheme,device selection and test method of the key modules of the radiometer system.It is concluded that the system sensitivity and various indica-tors can meet the requirements of atmospheric ozone inversion,and the correctness of the system design is verified by conducting atmospheric detection experiments and comparing the experimental results with the simulation results of Atmospheric Radiative Transfer Simulation Software(ARTS).The radiometer system meets the application requirements of stratospheric ozone concentration monitoring,early warn-ing and climate change research.
æè½½å¾®æ³¢æ¹¿åº¦è®¡è§æµçå°ç表é¢å大æ°çäº®æ¸©æ¯æ°å¼å¤©æ°é¢æ¥åæ°åç ç©¶çéè¦åºç¡æ°æ®æºãç±äºå¾®æ³¢æ¹¿åº¦è®¡ç³»ç»ååºç¹æ§å·®å¼ãå¨è½¨å·¥ä½æ¡ä»¶çååï¼ä»¥åæä¸å®æ åºåçå·®å¼ï¼ä¸åå«æå¾®æ³¢æ¹¿åº¦è®¡ãåä¸å¾®æ³¢æ¹¿åº¦è®¡æ°æ®å¨é¿æ¶é´èå´å é½åå¨ä¸å®çåå·®ã妿è¿äºåå·®ä¸è¿è¡ä¿®æ£ï¼åä¼å¯¹é¿æ¶é´åºååºç¨ï¼å¦æ°åç ç©¶çï¼å ·æè¾å¤§çå½±åï¼çè³å¯è½å¯¼è´é误çç»æãç±äºå¾®æ³¢è¾å°ç®åè¿ä¸åå¨ç»å¯¹åºåï¼æ æ³éè¿å°é¢ç»å¯¹åºåçä¼ éè¿è¡æä¸æ°æ®çç»å¯¹å®æ ï¼å æ¤éè¦å©ç¨å ¶ä»ç¸å¯¹å®æ æ¹æ³å¯¹æ¹¿åº¦è®¡çç¨³å®æ§åå ¶ååç¹å¾è¿è¡è¯ä»·ãæ¬æåºäºOMBï¼æ¨¡æåè§æµæ°å·®ï¼å®æ çææ³ï¼ç»å微波湿度计çç³»ç»ååºç¹æ§åæä¸å®æ åºæ¬åçï¼å»ºç«äºå¾®æ³¢æ¹¿åº¦è®¡å®æ åå·®çæ ¡æ£æ¨¡åâå宿 模åï¼ä»èå®ç°å岿°æ®çä¸è´æ§å®æ ã忥ç ç©¶ç»æè¡¨æï¼ä½¿ç¨å宿 模ååï¼FY-3C微波湿度计-II宿 ç»æçæ¶é´åºå稳å®ï¼åå§OMBåå·®ä¸çåç§å¼å¸¸æ³¢å¨ç°è±¡å¾å°è¯å¥½ä¿®æ£ãç±äºè¯¥æ¨¡åæ¯åºäºå¾®æ³¢æ¹¿åº¦è®¡çç³»ç»ååºç¹æ§å»ºç«çï¼å æ¤è¿ä¸æ¹æ³åæ ·éç¨äºå ¶ä»FY-3ç³»åå«æå¾®æ³¢æ¹¿åº¦è®¡æ°æ®ç宿 åå·®æ ¡æ£ï¼å®ç°FY-3ç³»åå«æå¾®æ³¢æ¹¿åº¦è®¡æ°æ®çä¸è´æ§å®æ ã
æ¬æå¨ç»¼è¿°å½é ä¸æè½½å¾®æ³¢è¾å°è®¡å岿°æ®å宿 ææ¯åºç¡ä¸ï¼ä»ç»äºé£äºä¸å·å«æå¾®æ³¢è½½è·ç¹ç¹ï¼ç»¼è¿°ä¸å¡è¾å°å®æ åå岿°æ®å宿 å ±æ§ææ¯ï¼éè¿°é£äºä¸å·å«æå¾®æ³¢è½½è·éè¿ä»ªå¨ç³»ç»å ¨é¾è·¯è¾å°ä¼ é仿çæå»ºå¨è½¨ç¹æ®å·¥åµè¾å°ä¿®æ£æ¨¡ååï¼ä»¥å½é åèè½½è·ä¸ºåèæ¶é¤ä»£é é´è¾å°å·®å¼çå岿°æ®å宿 ææ¯è·¯çº¿ï¼ç®ä»äºé£äºä¸å·å«æå¾®æ³¢è½½è·å¨è½¨åºæ¬ä¸å¡ç¶æä»¥åå岿°æ®å宿 ç ç©¶ææï¼å宿 çæçé£äºä¸å·å¾®æ³¢é¿æ¶åºL1ç§å¦æ°æ®éï¼ç»ä¸å½é å类载è·äº¤åæ¯å¯¹è¡¨ææ°§æ°å¸æ¶ééé¿æ¶é´åºåäº®æ¸©æ°æ®RMSE为0.77 Kï¼æ å差为0.28 Kï¼æ°´æ±½å¸æ¶ééå宿 åé¿æ¶é´åºåæ°æ®çRMSEæä¼è¾¾å°0.80 Kï¼æ å差为0.20 Kï¼çªåºéé以23.8 GHzçVæåéé为ä¾å宿 åé¿æ¶é´åºåæ°æ®çRMSEæä¼è¾¾å°1.29 Kï¼æ å差为0.15 Kï¼å¨å®æ åæå¤§RMSEä¸è¶ è¿1.5 Kãé£äºå«æå¾®æ³¢è½½è·ä¸åèè½½è·ä¹é´å ·æé常好çè¾å°ä¸è´æ§ãé£äºä¸å·å«æå¾®æ³¢è½½è·å岿°æ®å宿 ç»æä¸ºåç»å»ºç«é£äºå«æå¾®æ³¢è½½è·åºç¡æ°åæ°æ®éï¼FCDRï¼ãåå å«å ³é®æ°ååéçç½æ ¼åæ°åæ°æ®éï¼CDRï¼æä¾äºåºç¡æ§æ¯æã
In the calibration of Microwave Humidity and Temperature Sounder (MWHTS) onboard the Fengyun-3E (FY-3E) satellite, the ideal rectangular spectral response function is normally used. However, the measured spectral response function has in-band fluctuation, which will not only cause errors to the calibration, but also is essential to the subsequent data retrieval and assimilation applications. In this paper, the spectral response function (SRF) of five channels located near the frequency of 183.31-GHz is studied. The results demonstrate that different channels have different responses to the measured SRF and the ideal rectangular SRF. The closer the channel is the frequency 183.31-GHz, the maximum deviation is nearly 0.2 K. In addition, a constant noise, uniform noise, Gaussian noise and Chebyshev 1 ripple noise were added respectively. The greater the noise amplitude, the greater the brightness temperature deviation, and the results of four different noise was consistent. When the noise amplitude is set to 3 dB, the brightness temperature deviation reaches 0.1 K. The results can not only provide reference for the design of the sensor, but also provide a new idea for data calibration, so as to improve the accuracy of data calibration.
æ¬æåºäºä¸»æååæPCAï¼Principal Components Analysisï¼åéåç»éªæ¨¡æåè§£EEMDï¼Ensemble Empirical Mode Decompositionï¼éåªçåºæ¬ææ³ï¼å©ç¨æ¹è¿çèªéåºåªå£°æ»ä½éåç»éªæ¨¡æåè§£ICEEMDANï¼Improved Complete Ensemble Empirical Mode Decomposition With Adaptive Noiseï¼å¯¹åEEMDçæ¡å¸¦éåªæ¹æ³è¿è¡äºä¿®æ¹ï¼å¹¶å©ç¨è¯¥æ¹æ³å¯¹é£äºä¸å·CæãDæï¼FY-3CãFY-3Dï¼å¾®æ³¢æ¹¿åº¦è®¡ï¼MWHS-2ï¼å®é è§æµäº®æ¸©ä¸çæ¡å¸¦åªå£°è¿è¡äºåæãå ¶ä¸ä¸»æååæå¯¹æ°æ®è¿è¡éç»´ï¼å¾å°åæ«æçº¿ç主æååéï¼æ¨¡æåè§£æ¹æ³å解对åºåéï¼å©ç¨å模æè½éå¯åº¦ç差弿ååºå ¶ä¸çåªå£°å¹¶å»é¤ï¼éåç»åå©ä½æ¨¡æéæåºè§æµäº®æ¸©ï¼å®ç°åªå£°çæå¶ãéè¿å¯¹åå§ç®æ³ååç±»æ¹è¿åçæ¨¡æåè§£æ¹æ³éåªææç对æ¯ï¼ç»æè¡¨æä½¿ç¨ICEEMDAN坿æé¿å EEMD䏿®ä½åªå£°çé®é¢ï¼åå°éæè¯¯å·®ãæ°å¼åæç»æè¡¨æï¼æ¹è¿åçæ¹æ³ä½¿æ¹å·®è¿ä¸æ¥éä½0.020 K2ï¼ä¿¡åªæ¯æå0.031 dBï¼è¿ä¸æ¥æåäºç®æ³çéåªè½åã
The development history of microwave humidity sounder for three batches of polar-orbit-ing meteorological satellites of Fengyun-3(FY-3)and the technological breakthroughs and development progress made are introduced,covering the realization of key technologies and the design of key techno-logical indexes and testing and evaluation,as well as the scientific applications in numerical weather pre-diction,typhoon and rainstorm and other catastrophic weather prediction and monitoring,etc.,and the upgrading of the technology of satellite-mounted passive microwave atmospheric sounding is elaborated.Based on the current status and development trend of microwave atmospheric detection research at home and abroad,it focuses on the potential of microwave atmospheric detection by polar-orbiting mete-orological satellites in terms of meteorological parameter detection capability,detection accuracy,tempo-ral and spatial resolution,and application effectiveness.In view of the 2040 vision plan of the World Me-teorological Organization(WMO)and the new generation of polar-orbiting meteorological satellites of Fengyun-5 of China,a new high-performance microwave atmospheric integrated detection system with trans-representative signatures-hyperspectral microwave atmospheric detector-is proposed,and the technical way of on-orbit quantitative enhancement and the application prospect are briefly described.It also briefly describes the technical way and application prospect of quantitative enhancement in orbit,laying a foundation for the development of microwave atmospheric detection payload for Fengyun-5 me-teorological satellite.
å¾®æ³¢æ¹¿æ¸©æ¢æµä»ªï¼MWHTSï¼çééååºå½æ°ï¼SRFï¼ä¸è¬è¢«è®¤ä¸ºè¿ä¼¼äºç©å½¢å½æ°ï¼ç¶èä»å®é SRFçæµè¯æ°æ®æ¥çï¼MWHTSåä¸ªé¢æ®µä¸åééçSRFåå¨ä¸å®çå¸¦å æ³¢å¨ãæ¬æå©ç¨å¤§æ°è¾å°ä¼ è¾æ¨¡æå¨ï¼ARTSï¼æ¨¡æäºMWHTSä¸118 GHzåééä¸ååºæ¯ç亮温谱ï¼å¹¶è¾å ¥è³åæå»ºç«çMWHTSç³»ç»ä»¿ç模åä¸ï¼éè¿å®æ å¾å°äºä»ªå¨çè¾åºäº®æ¸©ï¼è¿èè¯ä¼°å®æµSRF对亮温æµéåå ¶åæ¼çå¤§æ°æ¸©åº¦å»çº¿çå½±åï¼å¹¶å©ç¨å«æå®æµæ°æ®è¿è¡äºå¯¹æ¯éªè¯ãç»æè¡¨æï¼äº®æ¸©åå·®ä¸å®é SRFçå¸¦å æ³¢å¨åç°çº¿æ§æ£ç¸å ³çå ³ç³»ï¼å½å¸¦å æ³¢å¨å¤§äº3 dBæ¶ï¼äº®æ¸©åå·®å¯ä»¥è¾¾å°0.2â0.5 KãSRFçå¸¦å æ³¢å¨ä¼é æå¤§æ°æ¸©åº¦å»çº¿åæ¼è¯¯å·®ï¼ç¹å«æ¯å¨é«åº¦ä¸º1.8 kmæ¶ï¼è¯¯å·®æå¤§å¯ä»¥è¾¾å°0.8â0.9 Kï¼è¯¥ä»¿çç»æä¸å«æå®æµæ°æ®ç»æä¸è´ãå æ¤å¨ä½¿ç¨æ°æ®ååæ¹æ³å¯¹æ°å¼å¤©æ°é¢æ¥ï¼NWPï¼è¿è¡æ¨¡ææ¶ï¼éè¦ç¹å«æ³¨æå ·æè¾å¤§SRFå¸¦å æ³¢å¨çééæå¼èµ·ç亮温åå·®ï¼è¿å¯¹äºæªæ¥å«ææ°æ®çåºç¨å ·æéè¦çç ç©¶ä»·å¼ã
This paper demonstrated the advantages of spaceborne hyperspectral microwave radiometer in retrieving temperature and humidity profiles. Build a forward model using the Atmospheric Radiative Transfer Simulator (ARTS) and input profile datasets from the ECMWF 137 level short range forecasts to calculate simulated brightness temperature. A physical retrieval algorithm (Optimal Estimation Method, OEM) was used to retrieve temperature profiles ranging from 0-40 km and humidity profiles ranging from 0-10 km. The results showed that 10 MHz can more effectively retrieve temperature and humidity profiles. The mean values of root-mean-square error integrated over the height are 0.6096 K (0.6093 K) and 2.6373% (2.7210%) for land (ocean) temperature and relative humidity profiles, respectively. The information content (IC) of different spectral resolutions slightly differs from OEM retrieval results. 10 MHz and 100 MHz spectral resolutions have maximum channel IC for retrieving temperature and humidity profiles, respectively. In conclusion, spaceborne microwave hyperspectral sounder can improve the retrieval accuracy of temperature and humidity profiles by increasing spectral resolution.
æè½½å¾®æ³¢æ¹¿åº¦è®¡åå°å宿 åå¨è½¨å®æ çæå¤§ä¸åæ¯å·æºç使ç¨ï¼å¨è½¨å®æ çå·æºæ¯å®å®å·ç©ºèæ¯æ¸©åº¦ï¼é常为2.7 Kï¼èåå°å宿 çå·æºé常æ§å¶å¨80â100 Kãè¿æ ·éè¿åå°å宿 å¾å°çé线æ§ç³»æ°æ¯å¦å¯ä»¥ç¨äºå¨è½¨å®æ ä¸ç´æ¯ä¸ä¸ªéå¸¸å ³å¿åå¼å¾ç ç©¶çé®é¢ãæ¬æéè¿å¨FY-3E微波湿度计åå°åççç©ºå®æ ä¸é¤äºä¼ ç»éè¦çå·çã忏©å®æ æºä¹å¤ï¼å¦å¤è®¾è®¡äºä¸ä¸ªç¬ç«çä½äº180â200 Kéè¿ç宿 æºãå©ç¨è¯¥éªè¯æºï¼æ¬ææåºäºä¸ç¹å®æ å ¬å¼ï¼åºäºå·ç©ºä¸åæ§å¹¶éè¿å¤æ¨å°å·ç©ºäº®æ¸©ç模æè§æµè®¡ç®é线æ§ç³»æ°ãéåéè¿æ¯è¾ä¼ ç»åæ°åé线æ§ç³»æ°æ¨å¯¼æ¹æ³çç»æï¼å¹¶å°ä¸¤ç»ç³»æ°å¸¦å ¥åä¸ç»æ°æ®ä¸åæä¸¤ç»åå°å宿 ç³»æ°ç¨äºå¨è½¨å®æ çéç¨æ§ãç»è®ºè¡¨æï¼éè¿å¯¹ä¼ ç»æ¹æ³åæ°æ¹æ³ç计ç®ç»ææ¯è¾ï¼åç°å°ä¸¤ç»éçº¿æ§æ¹æ³åºç¨äºå䏿°æ®éçç»æåå¨å·®å¼ï¼è¯´æä¼ ç»æ¹æ³å¾å°çåå°åç³»æ°åå¨è¯¯å·®ãå¹¶ä¸è¯¥æ¹æ³ç®åäºåå°åæ å®è¿ç¨ï¼æé«äºé线æ§ç³»æ°ç¨äºæä¸æ å®ç精度ã
In this paper, two millimeter-wave zero-bias Schottky detectors for the direct detection system of the CubeSat radiometer, with center frequencies of 89 GHz and 150 GHz, respectively, were designed and implemented. These designs were based on zero-bias Schottky diodes of ACST. A radial stub structure was adopted at the DC ground and output port with a tuning line for optimum impedance matching to achieve stable and high performance and broadband characteristics; this structure also makes the circuit easier to integrate with pre-level systems and more suitable for CubeSat radiometer miniaturization. Circuit structure and Schottky diode were analyzed, modeled, and optimized to obtain better performance. The results showed that the W-band detector has a typical sensitivity of about 2500 V/W in the range of 85 GHz to 95 GHz and a linearity of 0.9994 at 89 GHz. Moreover, the D-band detector has a typical sensitivity of about 1600 V/W in the range of 145 GHz to 155 GHz and a linearity of 0.9992 at 150 GHz. These results verified the advantages of the improved circuit structure in the detector and the feasibility of the direct detection system.