The analysis on distribution characteristics of atmospheric ducts based on ECMWF reanalysis data

Atmospheric ducts have significant impacts on electromagnetic wave propagation. Studying the distribution feature of atmospheric ducts is of great significance for analyzing electromagnetic wave propagation and effectiveness of radar and communication equipment. The feature values of atmospheric ducts are calculated based on the ERA-Interim reanalysis data, and these values are verified by rocketsonde data. On this basis, the feature values of global ducts are analyzed using the ERA-Interim data for the period of 2011—2016. The conclusions are as follows. The eastern part of the ocean and the western part of the continent in the trade wind belt are the high probability zone of the atmospheric ducts. There are six high probability zones and three little or no duct zones. The position, range, and probability of occurrence of these zones have seasonal variations. Season MAM (Mar—May) has the highest probability and the largest occurrence zone in the northern hemisphere, while Season SON (Sep—Nov) has the lowest probability and the smallest occurrence zone. Seasons DJF (Dec, Jan, Feb) and JJA (Jun—Aug) are between the two seasons. Season SON has the highest probability and the largest occurrence zone in the southern hemisphere, while Season MAM has the lowest probability and the smallest occurrence zone. The magnitude of atmospheric duct in the northern hemisphere is generally stronger than that in the southern hemisphere. Season MAM has the strongest magnitude of atmospheric duct in the northern hemisphere, followed by Season JJA. For Season SON, the sea areas with strong magnitude are the smallest, and the magnitude is the weakest. The magnitude of atmospheric duct in the South Pacific has no obvious seasonal variation, and its strength is weaker than that in the North Pacific. The strong magnitude zone of duct in the South Atlantic has the largest sea area and strongest in Season SON, and it has the smallest sea area and the weakest in Season DJF. The northern Indian Ocean has the strongest magnitude in Season MAM, which is the strongest zone in world ocean, and there is no atmospheric duct in Season JJA. The altitude of the atmospheric duct is low near the west coast of continent in the trade wind belt. As the distance from coast to the west increases, the altitude gradually increases. The high probability zone of the atmospheric duct is high altitude in Season SON and DJF in the northern hemisphere, the zone of high altitude is large, the low altitude in Season MAM and JJA, and the zone of high altitude is small. The high probability zone of the atmospheric duct is the high altitude in Season MAM and JJA in the southern hemisphere, and the zone of high altitude is large; the high probability zone of the atmospheric duct is the low altitude in Season SON and DJF, and the zone of high altitude is small. The altitude of atmospheric ducts in other low and middle latitudes offshore water is relatively low. In the inland sea areas surrounded by mainlands, the altitude of atmospheric ducts is the lowest.