Research On Detection Method Of Low-altitude Wind Shear Under Sea Clutter

With the development of world technology and economy,countries are developing and constructing maritime/marine airports,such as London's Third Airport,New York's LaGuardia Airport,and Macau Airport.However,due to the complicated weather conditions near the maritime/marine airport,civil aviation passenger planes taking off and landing at the maritime/marine airport will face many severe weather conditions,which will pose a major threat to the flight safety of the aircraft.The low-altitude wind shear is the "number one killer" that threatens the flight safety of the aircraft in many severe weather conditions.As an important part of aircraft avionics,airborne weather radar can perform low-altitude wind shear detection under the sea surface background,but it faces many difficulties.The first thing is that the sea clutter signals received by airborne weather radar will bury the low-altitude wind shear signal,makes it impossible to accurately estimate the wind speed,resulting in low-altitude wind shear cannot be accurately detected.The current low-altitude wind shear detection methods are mostly aimed at the background of the ground clutter.However,there are many differences between the ground clutter and the sea clutter.The movement of the sea surface waves will cause the space-time spectrum of the sea clutter to widen,which will increase the difficulty of clutter suppression and affect the accuracy of low-altitude wind shear detection.Therefore,it is of great significance to specifically study the low-altitude wind shear detection method under the background of sea clutter.Based on airborne phased array weather radar,research on the detection method of low-altitude wind shear under the background of sea clutter.The main contents are as follows:A low-altitude wind shear detection method based on spatial multi beam-time domain sliding window under the background of sea clutter is proposed.This method first aims at the distribution characteristics of dynamic sea clutter in the angle-Doppler domain,and adopts the space-time interpolation method to correct the clutter distance dependence,and then constructs the spatial multibeam-time domain sliding window space-time adaptive processing(STAP)structure,which adaptively processes the output of the same frequency Doppler channel,constructs a cost function to achieve wind speed estimation in the low-altitude wind shear field,and finally calculates the average F factor,which is compared with the alarm threshold to achieve low-altitude wind shear detection.In view of the small number of Independent Identical Distribution(IID)training samples,a low-altitude wind shear detection method based on sparse reconstruction is proposed,which can achieve accurate low-altitude wind shear detection using only a few small samples.Firstly,This method uses the sparse characteristics of forward-looking sea clutter in the angle-Doppler domain,constructs a sparse representation of the space-time snapshot signal by constructing a super-complete dictionary,and the sparse Bayesian learning algorithm is used to reconstruct the signal,estimate the clutter covariance matrix of the distance unit to be detected,then construct the space-time adaptive filter to suppress sea clutter and match the signal,construct the cost function to realize the wind speed estimation of low-altitude wind shear,finally calculate the average F factor to determine the risk of low-level wind shear,and realize the low-level wind shear detection.