This paper proposes two novel objective functions and a new heuristic optimization algorithm for rotating synthetic aperture passive imaging system which has non-uniform sampling scheme. Firstly, this paper introduces two objective functions named modified minimum electric charge energy and minimum error gridding, while the mostly used maximum baselines distance product objective function introduced by Cornwell will results in dense baseline distribution in centric and boundary area but sparse in the middle. To overcome the problem of updating global best position slowly, rising the risk of being trapped in local extremum by standard Particle Swarm Optimization(PSO), this paper introduces the novel Quantum-Goose Particle Swarm Optimization(QGPSO), which outperforms the existing method of global exploration efficiency and accuracy. Numerical simulations validate that these two functions provide more uniform radial baseline distribution and minimum error gridding objective function provides the most accurate reconstructed image. This method proposes reference for practical design and application of rotating thinned array.

Thinned rotating arrays of microwave/millimeter wave synthetic aperture imaging radiometer result in polar like visibility samplings where complex image reconstruction algorithms are in need and it is tough work to estimate important system parameters. To address this problem, a new method based on filtered back projection algorithm is proposed. In this approach, the system Point Spread Function (PSF) is obtained by 1-D Fourier-Bessel (Hankel) transforming from Dirac comb function. Spatial resolution and alias-free of view affected by radial and angular sampling intervals are analyzed by decomposing PSF into main lobe and a series of ring lobes. A new formulation to estimate the radiometric sensitivity of thinned rotating arrays by filtered back projection algorithm is also proposed. The consistency between the numerical and measured point spread function indicates that the proposed model is accurate.

Some thinned array, such as circle thinned array, is used by synthetic aperture interferometric radiometer to realize time-shared sampling. The thinned array may take non-uniform sampling of spatial frequencies due to antenna array structure optimization, the limitation of affined area and the physical size of antenna elements as well. In some traditional image reconstruction methods, non-uniform spatial frequency samplings are usually inserted to uniform Cartesian coordinate. And the spatial frequency densities are compensated. However, as the spatial sampling intensity is assumed to be quite smooth, these methods still bring errors and blurring in spite of different interpolation functions. Moreover, iterative methods that adopted straight Fourier transform are time consuming as they applied to non-uniform spatial frequency samplings. In this paper, another fast interactive image reconstruction method is introduced. The kernel of this algorithm is min-max formulation. The specific procedure of this method is as follows: (1)initiating the image; (2)taking non-uniform fast Fourier transform;(3)operating iterative conjugate gradient matched algorithm. The numerical simulating experiments show that, as spatial frequency samplings density is not smooth, the image can be still reestablished fast and accurately.

Interferometric synthetic aperture radiometer is an attractive conception that uses Fourier synthesis to achieve high spatial resolution avoiding the disadvantages of manufacturing and carrying large antennas. 183.31 GHz Interferometric aperture synthesis radiometer will play a significant role in detecting the vertical distribution of atmospheric water vapor, heavy rainfall and cloud liquid water. It makes great sense to provide important parameters for the weather prediction as well. This paper has discussed the analysis of interferometry model and design of the 183.31 GHz interferometer system with two elements. And then two main important tests like simulated point target interferometry and point target interferometry at various angles to get functional verification of the full-scale system are presented. Simulated point target interferometry experimental result which illustrates that the measured amplitude of visibility function is the same, and the results distribute on a round show good stability, which is cruci- al for a full-scale system. Point target interferometry at various angles shows that real and image parts of the complex visibilities are very close to the expected ideal orthogonal sinusoids. The relationship between baseline length and the real and image parts of the complex visibilities curve frequency is linear which verifies that visibility function and modified brightness temperature is Fourier transform pair alike.

Interferometric synthetic aperture radiometer is an attractive conception that uses Fourier synthesis to achieve high spatial resolution avoiding the disadvantages of manufacturing and carrying large antennas.183.31 GHz Interferometric aperture synthesis radiometer will play a significant role in detecting the vertical distribution of atmospheric water vapor,heavy rainfall and cloud liquid water.It makes great sense to provide important parameters for the weather prediction as well.This paper has discussed the analysis of interferometry model and design of the 183.31 GHz interferometer system with two elements.And then two main important tests like simulated point target interferometry and point target interferometry at various angles to get functional verification of the full-scale system are presented.Simulated point target interferometry experimental result which illustrates that the measured amplitude of visibility function is the same,and the results distribute on a round show good stability,which is crucial for a full-scale system.Point target interferometry at various angles shows that real and image parts of the complex visibilities are very close to the expected ideal orthogonal sinusoids.The relationship between baseline length and the real and image parts of the complex visibilities curve frequency is linear which verifies that visibility function and modified brightness temperature is Fourier transform pair alike.

The paper introduces a widely used atmospheric absorption models: MPM by Liebe in 1989. Using this absorption model, the paper simulates the temperature and humidity weighting functions and brightness temperature according to the different frequencies and bandwidth of the multi-channel ground-based microwave radiometer. The results show that simulated brightness temperatures are very well agreement with the observation values with an acceptable root mean square error. This paper uses widely used retrieval method of artificial neural network to obtain the water vapor density profiles and calculates the root mean square error of each dataset. Also, to improve the accuracy of retrievals, this paper adopts multi-layers neural network which has two hidden layers. The results show that the retrievals of water vapor density profiles based on ground-based microwave radiometer are agreement with the water vapor density profile which is observed by radiosonde. Grant Nos. GYHY200906035 China Meteorological Administration nonprofit sector (meteorology) special research

Microwave humidity sounder (MWHS)is one of payloads on the FENGYUN-3 A satellite (FY-3A). This paper introduces its structure, operation status and data reception and processing. the paper constructs an inversion model using artificial neural network algorithm, and has a comparison with advanced microwave sounding unit AMSU-B, the results demonstrate that the model can be operated successfully. Using the simulated brightness temperatures from MWHS from July to December 2008 in Beijing, the paper derives water vapor density profiles and has an analysis of root mean square. Meanwhile, it focuses on the cyclone "parrot" and typhoon "Sinlaku". The brightness temperature of channel one has been analysized when the cyclone comes (cyclone "parrot" land on china At 11 o'clock on the August 22, 2008 and "Sinlaku" on September 13, 2008). Therefore, this paper demonstrates that FENGYUN-3 A satellite MWHS can retrieve the water vapor density profiles, cloud liquid water and other related information. Also, in the process of monitoring the tropical typhoon and cyclone and judging the trend of them, FENGYUN-3 A satellite MWHS also plays an very important role.

Microwave emissions at various frequencies are known to contain information on atmospheric chemistry. Information about water vapor is of great interest at 183.31GHz. Interferometric synthetic aperture radiometer avoids the disadvantages of manufacturing and carrying large antennas at the expense of complexity. This paper has discussed the design of the 183.31GHz interferometer system with two elements based on imaging theory and retrieving algorithm of two-dimensional synthetic aperture radiometer. And then several important experimental results are presented.

This paper analysizes and retrieves atmospheric integrated water vapor content and liquid water content which are two critical parameters in the process of artificial rainfall and other weather forecasting and weather modification. According to the atmospheric sounding principle and experiment datasets this paper used linear regression method and nonlinear regression method to retrieve these parameters and then chose the better and suitable method-nonlinear regression method. The retrievals using both methods show that the paper successfully obtains the atmospheric integrated water vapor and cloud liquid water content with acceptable root mean square error. And using nonlinear regression method can obtain the integrated water vapor content and liquid water content which are considered as internal levels.

The paper introduces two widely used atmospheric absorption models: MPM by Liebe in 1989 and Ulaby in 1976. Compare between them based on ground-based microwave radiometer, this paper presents an atmospheric absorption model with improvement including local line absorption, noresonant dry air spectrum, water vapor continuum, suspended water droplet refractivity and rain effects. Also, using the improved absorption model, the paper simulates the temperature and humidity weighting functions and brightness temperature. The results show that in the retrievals of ground-based microwave radiometer, the improvement of atmospheric absorption can derive more accurate brightness temperatures which are more agreement with the actual measuring brightness temperatures.