Extreme conditions in Mediterranean Sea during race
22 October 2014
In October 2014, during Rolex Middle Sea Race in the Mediterranean participants started experienced strong winds and high waves.
06 September 2022
22 October 2014
By Maja Jeromel (Slovenian Environment Agency)
The Rolex Middle Sea Race is a highly-rated 607 nautical mile sailing race around Malta. Participants have to sail in a counter-clockwise direction, starting and finishing on La Valleta, Malta.
The 2014 race started on 18 October with a light southerly wind. However, on 22 October, participants experienced strong wind conditions. The wind built progressively from the northwest.
Storm force winds began to sweep the course and the face of the race changed, just as most yachts were reaching the exposed westernmost point at Favignana. Gust over 100km/h were reported and dozens of yachts retired from the race.
On the Meteosat-10 Airmass RGB image from 22 October 2014, 12:00 UTC, overlaid with MSLP and H500 ECMWF model outputs (Figure 1), a deep trough over central Mediterranean can be clearly seen. A high-pressure system above the Western Iberian Peninsula and a low above Italy and the Balkan Peninsula had resulted in a strong surface pressure gradient. The red areas on the same figure mark the intrusion of stratospheric cold air over northern Italy, Slovenia and Austria, which coincided with the modelled low on the H500 ECMWF model output.
The Natural Colour RGB, 22 October (Figure 2), shows the Mediterranean area was mainly cloudless except for a cold front band, white on the satellite image, extending from the north east coast of Algeria, Tunisia, Sicily and the southern Adriatic area.
There were also clouds over the Balearic Islands, Corsica and Sardinia, which are probably the result of orographic forcing. The light blue colour in Natural RGB shows higher and colder clouds.
There were also cloud structures above Benelux and France and even narrow cloud stripes in the Gulf of Lion indicating cold air advection above the sea. Similar narrow stripes can be seen between south Sardinia and Sicily in almost W-E direction and further in Ionian Sea and Gulf of Sidra in N-S direction. If we compare these narrow white stripes with modelled wind fields (Figures 3 and 4) we can see matching directions. Model shows also secondary surface wind jet out of Gulf of Genoa.
If we compare the directions from ASCAT and coastal in-situ measurements we can see relatively good agreement in general (Figures 5 and 6). Wind speeds in surface wind jet measured by ASCAT were 30–35kt (55–65km/h), while the average coastal wind speeds were more than 37–25kt (55–46km/h).
However, it must be taken into account that wind speeds on the coast are usually lower due to surface friction. For more accurate comparison with in-situ coastal measurements it is important to know the local specifications of measuring locations. Wind measurements on the oceanographic buoy in the Gulf of Lion measured an average wind speed of 40kt (74km/h) ~320° direction. Therefore, satellite and in-situ measurements are in a good agreement.
Figures 5 and 6 also show a good agreement for the wind speeds and direction between the ECMWF 10m wind and ASCAT wind (the colours of wind barbs are the same).
Meanwhile, the 12.5km RapidScat Winds product, from the instrument on board the International Space Station (Figure 7), showed winds speeds of up to 50kt (about 9 km/h) with a north-westerly direction, known as Mistral winds.
These extreme windy conditions over sea surface generated 'wind waves' (waves generated by local winds). The ECMWF wave model forecast significant wave height values of 4–5m in the area of the course race, this was confirmed by buoy measurements.
