Environmental predictions in the marine atmospheric surface layer (MASL) are imperative to optimize X-band radar system performance in marine environments. Evaporation ducts (ED) lead to anomalous propagation where characterization of EDs in the MASL occurs primarily through two methods: in-situ measurements and numerical modeling. This study investigates the differences in co-located and synchronous refractivity estimations from the CASPER-East campaign. Propagation predictions are generated for refractive profiles from in-situ measurements, Monin-Obukov boundary layer similarity theory, and numerical weather prediction forecasts. Variations in evaporation duct height (EDH) are found to be a primary driver of differences in propagation between the estimated refractivity profiles, where location of the EDH relative to the transmitter changes the sensitivity of propagation predictions to EDH estimates. Differences in propagation are large when EDH estimates span the transmitter height and the lowest EDH across the methods is small, regardless of how much variation there is in EDH estimates. When the lowest EDH is small and EDH estimates span the transmitter height there are differences in physical regimes causing large propagation discrepancies – e.g., leakage into versus trapping within the duct. Variation in EDH between the methods is greatest in stable environments. M-deficit and curvature of the refractive profiles also influence propagation specifically in scenarios when EDH spans the transmitter. When all EDHs are below the transmitter, EDH variance is the primary contributor to propagation variance, but M-deficit and profile curvature variance play a secondary role. M-deficits and curvature between the methods agree most often during periods of atmospheric stability.

中文翻译：

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大气折射率估计方法的比较及其对雷达传播预测的影响

海洋大气表层 (MASL) 的环境预测对于优化海洋环境中的 X 波段雷达系统性能至关重要。蒸发管道 (ED) 导致异常传播，其中 MASL 中 ED 的表征主要通过两种方法进行：原位测量和数值建模。这项研究调查了来自 CASPER-East 运动的同位和同步折射率估计的差异。为原位折射分布生成传播预测测量、Monin-Obukov 边界层相似性理论和数值天气预报。发现蒸发管道高度 (EDH) 的变化是估计折射率分布之间传播差异的主要驱动因素，其中 EDH 相对于发射器的位置改变了传播预测对 EDH 估计的敏感性。当 EDH 估计跨越发射机高度时，传播的差异很大，并且跨方法的最低 EDH 很小，无论 EDH 估计有多少变化。当最低 EDH 很小并且 EDH 估计跨越发射机高度时，物理状态的差异会导致大的传播差异——例如，泄漏到管道内与陷入管道内。在稳定的环境中，这些方法之间的 EDH 变化最大。当 EDH 跨越发射器时，M 缺陷和折射曲线的曲率也会特别影响传播。当所有 EDH 都低于发射机时，EDH 方差是传播方差的主要贡献者，但 M 缺陷和剖面曲率方差起次要作用。在大气稳定期间，方法之间的 M 缺陷和曲率最常一致。