Coherent Doppler lidar wind retrieval for a typhoon based on the genetic simulated annealing algorithm

A method of spectrum estimation based on the genetic simulated annealing(GSA)algorithm is proposed,which is applied to retrieve the three-dimensional wind field of typhoon Nangka observed by our research group.Compared to the genetic algorithm(GA),the GSA algorithm not only extends the detection range and guarantees the accuracy of retrieval results but also demonstrates a faster retrieval speed.Experimental results indicate that both the GA and GSA algorithms can enhance the detection range by 35%more than the least squares method.However,the convergence speed of the GSA algorithm is 17 times faster than that of the GA,which is more beneficial for real-time data processing.

Simultaneous reconstruction of temperature distribution and radiative properties in participating media using a hybrid LSQR-PSO algorithm

A hybrid least-square QR decomposition （LSQR）-particle swarm optimization （LSQR-PSO） algorithm was devel- oped to estimate the three-dimensional （3D） temperature distributions and absorption coefficients simultaneously. The outgoing radiative intensities at the boundary surface of the absorbing media were simulated by the line-of-sight （LOS） method, which served as the input for the inverse analysis. The retrieval results showed that the 3D temperature distribu- tions of the participating media with known radiative properties could be retrieved accurately using the LSQR algorithm, even with noisy data. For the participating media with unknown radiative properties, the 3D temperature distributions and absorption coefficients could be retrieved accurately using the LSQR-PSO algorithm even with measurement errors. It was also found that the temperature field could be estimated more accurately than the absorption coefficients. In order to gain insight into the effects on the accuracy of temperature distribution reconstruction, the selection of the detection direction and the angle between two detection directions was also analyzed.

ERROR COMPARISON OF WIND FIELD RETRIEVAL FROM SINGLE AND DUAL-DOPPLER RADAR OBSERVATIONS

The error distributions of the wind fields retrieved from single and dual-Doppler radar observations are given in this paper.The results indicate that the error of dual-Doppler retrieval depends on the position in the scan region of the dual-Doppler radar.The error of single-Doppler retrieval by using velocity azimuth processing(VAP)technique de- pends on the angle between the directions of wind and the radar beam.Generally,the winds retrieved from single Doppl- er radar are close to those retrieved from dual-Doppler radar.But,the error distribution of the single-Doppler retrieval is different from the dual-Doppler retrieval.We simulate the retrievals of single Doppler observation by the use of the output wind data from a 3-D numerical model of severe convection.The comparison of the simulated single-and dual-Doppler retrievals shows that the VAP may be a suitable technique for the operational analysis of mesoscale wind fields.It can also be used as a supplement to wind field retrieval in the field experiment.

RETRIEVAL OF HORIZONTAL WIND PERTURBATION FIELDS FROM SIMULATED SINGLE DOPPLER RADAR OBSERVATIONS

The application of the single Doppler radar dataset analysis is usually confined to the assumption that the actual wind is linearly distributed or uniform locally.Following some dynamic features of convective weather,a conceptual model of moderate complexity is constructed,wherewith a horizontal wind perturbation field is retrieved directly from the single Doppler radar measurements.The numerical experiments are based on a 3-D cloud model-generated convective cell,whose radial velocity component is taken as the radar observations that are put into the closed equations based on the conceptual model to retrieve the horizontal wind perturbation field.After the initial field is properly treated,the retrieval equation is solved in terms of the 2-D FFT technique and the sensitivity to noise is examined. Finally,contrast analysis is done of the retrieved and the cloud model output wind fields,indicating the usefulness of the approach proposed in this paper.

WIND SHEAR IDENTIFICATION WITH THE RETRIEVED WIND OF DOPPLER WEATHER RADAR

Wind shear reflects that the wind field is not uniform, which is one of the primary factors which make the retrieval of the wind field difficult. Based on volume velocity process(VVP) wind field retrieval technique, the intensity of wind shear is identified in this paper. After analyzing the traditional techniques that rely on the difference of radial velocity to identify wind shear, a fixed difference among radial velocities that may cause false identification in a uniform wind field was found. Because of the non-uniformity in wind shear areas, the difference of retrieved results between surrounding analysis volumes can be used as a measurement to show how strong the wind shear is. According to the analysis of a severe convective weather process that occurred in Guangzhou, it can be found that the areas of wind shear appeared with the strength significantly larger than in other regions and the magnitude generally larger than4.5 m/(s·km). Besides, by comparing the variation of wind shear strength during the convection, it can be found that new cells will be more likely to generate when the strength is above 3.0 m/(s·km). Therefore, the analysis of strong wind shear's movement and development is helpful to forecasting severe convections.

Temperature field reconstruction of 3D luminous flames based on light field tomography theory

Standard plenoptic camera can be used to capture multi-dimensional radiation information of high temperature luminous flame to reconstruct the temperature distribution. In this study, a novel method for reconstructing three-dimensional temperature field is proposed. This method is based on the optical tomography combined with standard plenoptic camera. The flame projection information from different planes is contained in one radiation image. In this model, we introduced the effective concept of the nearest neighbor method in the frequency domain to strip the interference of redundant information in the projection and to realize three-dimensional deconvolution. The flame emission intensity received by the pixels on the charge-coupled device sensor can be obtained according to the optical tomographic model. The temperature distributions of the axisymmetric and nonaxisymmetric flames can be reconstructed by solving the mathematical model with the nearest neighbor method. The numerical results show that three-dimensional temperature fields of high temperature luminous flames can be retrieved, proving the validity of the proposed method.