基于一次走航观测分析南海北部大气波导特征OA

Atmospheric ducts significantly affect radar's performance.Accurately diagnosing and forecasting of atmospheric duct layers thus has considerable value in economic and military fields.The scarcity of routine observations hampers the understanding of atmospheric ducts over the sea.This study uses a one-month continuous radiosonde experiment in the northern South China Sea to diagnose the characteristics and discuss the mechanism of the atmospheric duct.The conclusions are as follows:(1)The evaporation ducts appeared every day during the experiment,with an average duct height of 50 m and an average intensity of 64.7 M.(2)The elevated ducts appeared in 90%of the observation period,with an average duct height of 1 004 m,an average thickness of 109 m,and an average intensity of 6.1 M,with a nearly identical refractivity gradient within the trapping layer of about-0.15 M m-1.(3)The atmospheric humidity dominates the primary refractivity gradient of both types of the ducts,while the stratification of atmospheric temperature usually tends to suppress the evaporation ducts but contributes to the elevated ducts.This study has further confirmed the characteristics of atmospheric ducts in the South China Sea,supporting the simulation studies of electromagnetic propagation.