Abstract:

Abstract:This article proposes the hybrid method to inverse the equivalent electric charge of thunder cloud based on the data of multi-station atmospheric electric field. Firstly, the method combines the genetic algorithm (GA) and Newton method through the mosaic hybrid structure. In addition, the thunder cloud equivalent charge is inversed based on the forward modeling results by giving the parameters of the thunder cloud charge structure. Then an ideal model is built to examine the performance compared to the nonlinear least squares method. Finally, a typical thunderstorms process in Nanjing is analyzed by Genetic-Newton algorithm with the help of weather radar. The results show the proposed method has the strong global searching capability so that the problem of initial value selection can be solved effectively, as well as gets the better inversion results. Furthermore, the mosaic hybrid structure can absorb the advantages of two algorithms better, and the inversion position is consistent with the strongest radar echo. The inversion results find the upper negative charge is small and can be ignored, which means the triple-polarity charge structure is relatively scientific, which could give some references to the research like lightning forecasting, location tracking.

Abstract:Considering the problem of too large area the shading disc covered, complex shadow band coefficients and too big diffuse radiation measurement bias, an automatic shading device for diffuse radiometer is designed and realized. Set a shading ball on the automatic sun tracker, drive linkage parallelogram structure with the declination axis arm, the shading ball can rotate synchronously with the apparent motion of the sun and shade beam radiation measured with pyranometer, thus shading beam radiation and measuring diffuse radiation can be realized automatically. The comparison test results show that the automatic shading device can realize diffuse radiation measurement automatically, the accuracy of diffuse radiation readings can get a 18.7% improvement compared with traditional measure system, greatly improves the reliability and accuracy of the diffuse radiation measurement.

Abstract:The FDR automatic soil moisture sensor must determine reference frequency in the air and water, Experimental studies show that, The water reference frequency is influenced by water temperature. The variation of the reference frequency of the sensor is measured with the change of the water temperature, then analysis the influence of the volume water content measurement of the sensor, analysis found that the error is not more than 3% for the measurement of the volumetric water content of the temperature.

Abstract:Rainfall monitoring is one of the most important meteorological observation elements for the disaster weather. The maintenance of current tipping bucket rain gauge and weighing type rain gauge is a critical issue. The optical rainfall sensor based on CCD linear array is mainly studied in this paper. Because of the maintenance-free time and good adaptability, it can be widely used in the automatic rainfall monitoring in severe environment and have a good perspective in using.

Abstract:According to the phenomenon of “four more” and “four low” problems in the observation stations, the surface-based meteorological observing system can’t adapt to the change of the adaptive observation equipment and reduce of business intensification. A station integrated system is proposed, which can be configured, connected and extended to all kinds of observation equipment. And the integrated processor is designed, supporting a variety of communication interface standards. Flexible configuration, connection and expansion between conventional and new type of meteorological observation equipment are supported. It is capable for online calibration and maintenance of observation equipment. The effectiveness of automatic observation equipment is totally achieved to provide basic information support for disaster prevention and mitigation and national economic development.

Abstract:Observation of rain drop size distribution (DSD) with a vertical pointing micro rain radar (MRR) has important significance in the precipitation measurement field. The Mie theory of large particle, vertical wind and air turbulence have great influences on the retrieval of DSD measured by MRR. This paper simulates the process of how three factors affect the inversion of DSD and the calculation of other precipitation parameters, then makes the errors analysis. The Mie theory of large particle is more suitable for the scattering of the precipitation particle than Rayleigh approximation, which can have a correction for the underestimation of number density of small droplets and the overestimation of that in middle field. The vertical wind results in inaccurate estimation of particle terminal velocity, so its diameter is measured with some errors by empirical relationship, which affects the calculating accuracy of radar reflectivity and rain rate. Air turbulence can broaden the power spectral density, of which the impact on the inversion results of DSD are concentrated in small droplets field. Then the measured data by MRR is analyzed and the results prove the impacts of those factors. Finally, according to the analysis and application limits, the prospect of the future research trend of particle size distribution is conducted.

Abstract:In order to diminish the effect of the ambient light and CCD pixel non-uniformity to the Precipitation Micro-physical Characteristics Sensor, a modified calibration scheme was designed and calibration experiments in sunny, cloudy, night, different location of sample space were carried out. Firstly, the characteristics of particle images which affected by ambient light and different location of sample space were analyzed. Secondly, the relevance between particle image features and parameters of image processing were discussed. Finally, the parameter setting scheme were determined, the radium of median filtering algorithm is 3 pixels, the defocusing radius of point spread function(PSF) is 7 pixels, the radium of erosion is 3 pixels, and the binary threshold is obtained from the -thresh relationship. The results show that the new scheme could deal with the image calibration well, the average errors of equivolumetric diameter was 0.041mm with standard deviation of 0.115mm, and the average errors of the axis ratio was 0.011 with standard deviation of 0.085. The new scheme works well in the field observation too, the observed axis ratio is consistent with the empirical relationship that proposed by Beard. The relative error of accumulation precipitation is -3.06% after calibration, which is improved 1.94% lower than the initial one without calibration.

Abstract:Clouds are crucial regulators of both weather and climate. Properties such as the amount, type, height, distribution and movement of them have an impact on the earth's radiation budget and the hydrological cycle, thus cloud observation is very important. The disadvantages of zenith pointing measuring instruments and whole sky visible imagers limit the application of them. A summary of the actuality and application of ground-based whole sky infrared cloud measuring instruments and analyses of the techniques of radiometric calibrations, removal of atmospheric emission and calculation of cloud cover, amount, type are conducted to promote the automatically observation of the whole sky. Fully considering whole sky infrared cloud sounding theories, techniques and applications, there are still a lot of studies on improving the properties of instruments, enhancing the techniques of cloud base height measurements and establishing instrumental cloud classification criterion before actual operations.