Synoptic Scale Factors Involved in the Appearance of Tropospheric Ducts in the Caribbean Sea

Abstract

Tropospheric ducts are an abnormal condition of the atmosphere that affects the propagation of electromagnetic waves, which has a direct impact on the performance of various radio systems, including mobile telephony, which is especially sensitive to these interferences in communications. In Cuba, there is only one investigation to date focused on the formation of tropospheric ducts. Therefore, studying this topic and its relationship with atmospheric weather is novel. Knowing what meteorological situations lead to the formation of these communications interference events allows us to alert the relevant authorities and take appropriate measures in time. In this study, we investigated the use of numerical model outputs for the detection of the occurrence of tropospheric ducts. Based on an ERA5 reanalysis (which was feasible for the development of the research) we determined the characteristic atmospheric parameters enabling the formation of the tropospheric ducts, as well as the conditions of synoptic scale that favor their appearance. The first result revealed that the mean thickest ducts (between 75 m and 80 m) are seen more frequently in the March–May quarter, while in September and October these values are reduced by half, oscillating between 40 m and 45 m. In another analysis, we determined that the presence of stable atmospheric conditions in combination with a humid layer at low levels favors the appearance of this phenomenon. Therefore, days with a predominance of subtropical high pressures in combination with the passage of tropical waves through the seas south of the island of Cuba, or with the arrival of migratory anticyclones, guarantee this stability in addition to surface relative humidity values close to 80%.

Keywords

• tropospheric ducts
• troposphere
• weather
• atmospheric stability
• ERA5