Thanks to 5-GIT and the impressive power provided by Google Earth Engine, we can create a single image being the result of a composition of all SENTINEL-1 satellite passes over vast areas and large time spans. For each pass and pixel, only the highest values are considered so to better isolate the interferences captured by the sensor.
Fig.1 shows the whole Mediterranean Sea as captured by SENTINEL-1 satellites across the whole of 2018, I then roughly coloured the interferences over sea (red) to isolate and better analyse radar activity.
Other than land based, possibly Patriot, installations (Israel, Italy and Greece), the data shows a decently large amount of interferences captured by the C-SAR sensor over sea areas, this got me to investigate potential sources for them and after reviewing all vessels from all navies which operate regularly in the Mediterranean I came to the following potential sources. (there might be more, will add update the post I find them or if some reader points them out).
Horizon class frigates
Italy and France are operating two vessels each of the Horizon class, the vessels main radar is the EMPAR (SPY-790) a C band (IEEE) passive electronically scanned array radar with a reported range of over 300 miles for high altitude air traffic. For both Italy and France, the Horizon class frigates are the most advanced air defence frigates in their navies.
Italian “aircraft carrier” Cavour
The flagship of the Italian navy employs, among many other radar systems, the same EMPAR radar used on the Horizon class frigates.
FREMM frigates (Italian version)
The Italian version of the FREMM frigates employs the new KRONOS Grand (MFRA) from Leonardo which is a direct evolution of the EMPAR (SPY-790) and still operates in the C band. Currently Italy has 9 frigates of the class operative and one undergoing sea trials.
French version of the frigate (which also Egypt and Morocco purchased) doesn’t employ C band radars.
This 15 vessels (2 French and 13 Italian) could all be responsible for the interferences captured over the Mediterranean Sea both during their training operations and actual deployments. I’m currently not aware of other vessels / countries operating in the Mediterranean and employing C band radars (but if I find more, I will update the post, and if you know of others, please contact me, would love to know about them).
A good testing ground / verification area
Italy launched in 2015 the still ongoing operation “Mare Sicuro” which, supported by the Italian Navy, has the goal to patrol the sea between Italy and Libya, support ground operations of the Italian army on Libyan soil, monitor and guarantee the safety of sea traffic in the area and monitor and interdict terroristic and smuggling activities. Among the vessels assigned to the mission there are both Horizon and FREMM class frigates.
Therefore the sea off Libyan coasts should show at least some interference activity. And….. It does, with actually some potentially interesting results.
The animation above is made of over 2 years of monthly compositions of SENTINEL-1 data, it shows us how the Italian operation evolved and intensified through time with periods of much higher activity then others and a general shift in the area of interest from a sea area just north of Tripoli to one east of Misrata.
Unfortunately we can’t (yet ?) discern exactly the radar model just from the interferences captured by SENTINEL-1 sensors, and satellite images I have access to have not enough resolution to discern the differences between Horizon and FREMM class vessels, much less to identify the country they are from.
Some of the interferences captured over the mediterranean are very plausibly from the two French Horizon class frigates, but with thirteen vessels capable of generating them (compared to two from France) we can safely assume that Italy is responsible for most of the SENTINEL-1 detectable military naval “traffic” in the Med.
If any reader knows of other C band radars operating in the Mediterranean Sea please let me know, would love to keep this list updated with additional discoveries.
You can read more about SENTINEL-1 and how and why it can be used to track some military radars here.
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