Mastodawn

We're changing _everything_.

"Future projection indicates a consistent increase in surface refractivity across West Africa throughout the 21st century, with stronger amplification under the high – emission scenario. The largest increases occur along the humid coastal belt, reaching approximately +15 to +20 N-units by the late century, while the Sahel exhibits comparatively smaller changes. Relative changes show that refractivity increases by about 6-7% in the Equatorial Monsoon zone and 4-5% in the Tropical Savannah zone under SSP5-8.5. Scenarios divergence becomes pronounced after mid-century, highlighting the growing influence of emission pathways.

These changes are driven by enhanced atmospheric moisture and temperature increases associated with global warming. Th result demonstrate the importance of ensemble-based approaches for reducing model uncertainty and provide critical insight for climate-sensitive applications, such as radio wave propagation and telecommunication planning across West Africa."

#ClimateChange
#RFpropagation
#RadioFrequencyPropagation
#ducting

https://www.sciencedirect.com/science/article/abs/pii/S1364682626000957?dgcid=rss_sd_all

Imogen May 5, 2024

#Microwave #ducting #Radio

Doug Bostrom Dec 19, 2023

What hams working QRP at higher frequencies love: #ducting!

"...we show that at the time of the missile launch the prevailing weather conditions allowed a ground-based radar to detect targets far beyond the normal radar horizon through anomalous propagation conditions. During such conditions, the atmospheric index of refraction decreases rapidly with height, making electromagnetic radiation bend downward to, partly or fully, compensate the curvature of the Earth."

https://journals.ametsoc.org/view/journals/bams/104/12/BAMS-D-23-0113.1.xml

Anomalous Propagation and the Sinking of the Russian Warship Moskva

Abstract On 13 April 2022, the Russian warship Moskva was hit by two Ukrainian Neptune anti-ship missiles in the Black Sea, leading to its demise. Before launching an anti-ship missile, a target must first be detected and positioned, for example, by an accompanying radar system. However, when the missiles hit the Moskva she was well beyond the normal radar horizon of any ground-based radar system, making the ship undetectable under normal circumstances. Using meteorological reanalysis data, we show that at the time of the missile launch the prevailing weather conditions allowed a ground-based radar to detect targets far beyond the normal radar horizon through anomalous propagation conditions. During such conditions, the atmospheric index of refraction decreases rapidly with height, making electromagnetic radiation bend downward to, partly or fully, compensate the curvature of the Earth. The results show that atmospheric conditions must be considered carefully, even during warfare, as their impact on radar wave propagation can be considerable.

AMETSOC