The satellite-to-ground optical link is greatly influenced by atmosphere, the intensity of laser beam would attenuate up to tens of dB after transmitting through the clouds, which induces that the laser communication system should work under visually cloud-free condition. So optical link availability must be considered when the optical communication system is designed and the ground station location is selected. Based on ten years’ statistics data of cloud cover in different cities across our country, the usability of ground station is calculated by using a simple model. The result can provide suggestions for selecting satellite-to-ground optical communication ground station location.

Contrast to the measurement results of thermometer device, the accuracy of the measurement results by atmospheric coherence length monitor was certified. The deviations of the measurement results and the reasons for them were analyzed. Horizontal atmospheric coherence length at Bohe sea level and seaside and in Hefei had been measured by atmospheric coherence length monitor. The results show that horizontal atmospheric coherence length at sea is greater than that at seaside and it is the smallest in Hefei. Horizontal atmospheric coherence length in Hefei has typical diurnal variation and changes about 4?10 cm at morning transition moment and 4?15 cm at evening transition moment. Horizontal atmospheric coherence length at seaside changes about 8?15 cm and its feature is the same as Hefei and it keeps about 12 cm after evening transition moment. Horizontal atmospheric coherence length at sea changes about 9?12 cm at morning transition moment while it increases rapidly from 15 cm to 50 cm and then decreases sharply to 28 cm after about 2 h at evening transition moment. Taking the characteristics of different underlying surface, weather condition and the influence of the conversion between sea wind and land wind into consideration, the reasons of these experimental results are given.

Based on the long-term observations from Meridian Project lidars, the density overturning phenomena in the sodium layer above Beijing and Hainan are statistically analyzed. It is found that the density overturning structures generally occur in the bottomside of the sodium layer and typically last for 2?8 h with a width of 2?7 km. The observation results reveal that, the occurrence of those overturning structures are always accompanied with the propagations of large-scale gravity waves, and the disappearance are also related to the breaking process of large-scale gravity waves. These observations indicate that the convective instabilities arising from the interaction of large- and small-scale waves are probably another main reason for the breaking of large-scale gravity wave, except for the dynamic instability and the shear.

The simulation of laser atmospheric transmission in laboratory has proceeded upon liquid crystal spatial light modulator. Zernike polynomial was used to produce static atmospheric turbulence phase screen based on isotropic Kolmogorov turbulence model. r0=0.1 m and r0=0.05 m are the atmospheric coherent length under the different turbulence intensity. Dynamic turbulence screen was based on the turbulence freezing method and was loaded in the driver of LC-SLM. Logarithmic intensity probability density distribution at the receiving terminal is close to normal distribution, the determinal coefficients is above 0.9. Arrival angle fluctuation variance is σ1=7.1μrad and σ2=7.49μrad, and the spot concentrated within 2 pixels. The results are consistent with the actual field and have achieved good effect in laboratory.

Using the NCEP/NCAR 1°×1° final analysis data, Doppler radar data and Guiyang sounding data, the thunderstorm occurred at Guiyang airport during September 9?10, 2010 was analyzed by circulation pattern, divergence field, vertical motion, moisture flux divergence, K-index and radar plane position indicator (PPI) images. It is indicated that the shear line in east of Sichuan moving to the southeast arises thunderstorm, which is caused by conversion of upper air steering flow under the weakened and east retired subtropical anticyclone in 500 hPa. The upper air divergence and low-level convergence provide a favorable condition to the vertical motion. The strong moisture flux provides an enough moisture condition to development and maintenance of convection. The sounding data and K-index reflect the instability air condition evoking the thunderstorm.

The monitoring of phytoplankton growth state was based on chlorophyll fluorescence, mainly by using the modulated fluorometer. The changes in PSII performance of the photosynthetic apparatus have been explored by applying chlorophyll fluorescence technique. Chlorophyll fluorescence of microcystis aeruginosa and chlorella vulgaris were measured by system developed in lab. 450 nm LED were selected as excitation light source, which was used to obtain fluorescence at pigment level and light-adaptation. LD was used to supply saturation pulse which could interrupt photochemical reaction briefly. The photochemical reaction efficiency Yield was measured between phytoplankton cultivated in normal light and in control which placed in a darkroom. The maximum relative electron transport rate ETRmax tested under different light-adapted state, light use efficiency α and light damage parameter β were investigated, fluorescence induction curves and light response curves were measured, and the determination of phytoplankton growth state can be achieved.

High sensitivity for gas detection can be achieved by modulation spectroscopy technology based on harmonic detection, and the best analytical performance depends on the system modulation parameters optimization. Harmonic signal characteristics of infrared laser modulation spectroscopy is studied, and the relationship between the modulation parameters and corresponding harmonic signals is analyzed. Experiments and validation analyses are carried out for the typical infrared diode laser spectroscopy gas detection system, the optimal modulation system parameter is determined through the experimental analysis of the harmonic signal characteristics for different modulation voltages.

In the case of NaNO3 and NaCl, airborne salt particles from the ocean and alkaline lakes, the effect of inorganic salt particles with and without organic coating resulting from the low volatility products of the reaction of α-pinene with ozone at room temperature at 1 atm in air on light scattering was reported. Light scattering at 450 nm, 550 nm and 700 nm was measured by using TSI 3563 integrating nephelometer on particles whose size distribution was independently determined by using a scanning mobility particle sizer (SMPS). The measured values were compared with the calculated results through Mie theory. The results show that as salt takes up low volatility organics in the atmosphere and the geometric mean diameter increases, the effect on light scattering may be well predicted from the change in size distribution under conditions when the organic coating is small relative to the core size. However, for a given particle diameter, light scattering decreases as the relative contribution of the organic component increases. Thus, light scattering by salt particles with a specific size distribution will be reduced when organics comprise a significant portion of the particles. This will lessen their impact on the visual range compared to pure salt particles, but also lead to less counterbalancing of the troposphere warming due to greenhouse gases.

It’s beneficial to improve the recognition accuracy of infrared target in use of short wave infrared absorption band images. The radiation features of ground high temperature target that can be detected by short wave infrared absorption channels are influenced by atmospheric parameters, remote sensor parameters except for the temperature of the target. For different atmospheric parameters, the radiation data of forest fire and background were obtained systematically by simulation method and an analysis were carried out between them. Results showed that the bandwidth played a major role in the SNR of detecting high temperature targets, and the atmospheric model was in the second place. In the short wave infrared water absorption channel, the radiation features of the forest fire and the background were significantly different. The total radiation on the pupil of the remote sensor of the background around the 4.3 μm is mostly affected by path radiation, while around the 2.7 μm it mostly affected by atmospheric column water vapor.

To improve the efficiency of the polarimetric image fusion methods via NMF, a fast fusion method based on sparse NMF was proposed. Firstly, the polarization parameter images were acquired by computing from intensity images of different polarization angle. The original data set was organized by the polarization parameter images. Secondly, the sparse constraint was added to NMF and the cost function was solved by online dictionary learning algorithm of sparse representation. Then, the data set was factorized by sparse NMF and three feature basis images sorted by definition and variance were obtained. Next, after histogram matching, these three sorted feature basis images were mapped into three color channels of HSI color model. Finally, the fused image was achieved by transforming the image from HSI to RGB color model. Compared with the method based on NMF, the running time is improved with 120 times. One fusing process can be finished in 1.5 s. Experiment results show that the proposed method not only has good fusion results but also enhances the running efficiency evidently.

In the adaptive optics(AO) system, imaging is a very important process. The imaging process of the detectors and Hartman-Shack wavefront sensor in the AO simulation system is calculated with two-dimensional discrete convolution, whose numerical algorithm can be implemented with fast Fourier transformation (FFT). With the increase of the matrix size, the computation of convolution increases dramatically, and becomes a bottleneck of the AO system. To solve the problem, convolution on graphic processing unit(GPU) was implemented, which is a powerful accelerator in modern high performance computers. By applying various optimizations, significant performance improvement is obtained. On the NVIDIA Tesla C2050 GPU, a speedup of 5 to 24 times compared to serial program on the CPU with different image sizes is achieved.

The scale and brightness of the laser beacon play an important role in the ultimate accuracy of wave-front sensor and consequently determine the performance of the adaptive optics(AO) system. The relationship between the parameter of the laser beacon and the AO system performance, which is demonstrated through Strehl ratio, is discussed. Considering the application of laser beacon for the moving target, the equivalence between laser beacon and the cooperated beacon is presented.