Near-Sea Surface Meteorological Parameters Influences on Electromagnetic Wave Propagation

The modified refractivity <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(M)$</tex> has a direct impact on the operational effectiveness of radio systems such as radar. Because the near-sea surface is affected by ocean spray, solar radiation, etc., the sea-air interaction is more intense, resulting in more dramatic changes in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$M$</tex> at near-sea surface. In order to analyze the influence of meteorological parameters changes on the electromagnetic (EM) wave propagation in near-sea surface, this paper obtained the measured data of near-sea surface meteorology and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$M$</tex> in the South China Sea by Shiptime Sharing Project. Under different atmospheric conditions, the change of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$M$</tex> deviation of the fitted <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$M-\text{curve}$</tex> from the measured <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$M$</tex> is comparatively analyzed at the near-sea surface. The influences of their differences on the EM wave propagation loss is further analyzed based on the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$M-\text{curve}$</tex> obtained separately according to whether or not consider the meteorological parameters of the near surface. The results show that at near-sea surface, whether or not to consider the meteorological parameters will lead to deviations in the calculation of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$M$</tex>, and will cause different degrees of EM wave propagation loss under different atmospheric conditions. The larger deviation is as high as 32.78 percent with the EM wave propagation loss. Therefore, in order to improve the performance of radar and other radio systems, the observation of near-sea surface meteorological parameters should not be ignored.