Steve,

Sea surface state (MS) is determined visually and depends upon wind force. Wind force is visually described both in words and in Beaufort wind scale numbers (Forces).

We have made an attempt to review manuals and guides on ship wind observations and so far managed to find the only one, namely, “Instructions to hydrometeorological stations and posts”(Issue 9, Part 2, 1948), which gives the joint table of wind force and sea surface state described by the so-called Beaufort-Simpson scale (Table 1). This table was used in Russian observations to estimate both wind force and the MS parameter.

In the period of 1962-1992 the same Beaufort scale was used and word description of indicators required to define the surface state of an ocean, sea, lake or large water body (MS) corresponds to that given in Table 3, which we included into the format.

Since 1992 the Beaufort scale has been modified. Wind speed increased and the corresponding wind force given in numbers remained unchanged (Table2).

In original historical tables the MS parameter has already been encoded and given in numbers.

Russian national manuals on ship observations do not mention that Beaufort scale should be used to estimate MS. They give only Table 3, which we include into the format.

In my opinion, when MS is converted to wind force Beaufort scale used at the time, when observations were made, should be applied.

The digitization work is go on OK. At present time we prepare 100 cruises-files with meteorological and actinometric observations and forwarding to NCAR in a week.

Regards,

Svetlana

Table 1

Wind force, wind speed and sea surface state

Wind force

/ Wind speed m/s / Visual wind force indicators observed on board a ship / Sea surface state with wind waving
Beaufort numbers / Word description / Word description / Sea surface state
in numbers / Indicators for determining actual wind force and wind waving
0 / Calm / 0,0-0,5 / Flags are still / Calm glassy / 0 / Like a mirror
1 / Light airs / 0,6-1,7 / Calm rippled / 1 / Ripples
2 / Light breeze / 1,8-3,3 / Flags slightly waver in the wind / Smooth wavelets / 1-2 / Small wavelets, no breaking, no foam
3 / Gentle breeze / 3,4-5,2 / Flags flap in the wind / Slight / 2 / Large well-defined wavelets, some breaking, glassy foam, flocks of sheep here and there
4 / Moderate breeze / 5,3-7,4 / Small flags and a pendant in streaks
(stretch) / Slight to Moderate / 3 / Small waves, breaking, flocks of sheep everywhere
5 / Fresh breeze / 7,5-9,8 / Big flags in streaks / Moderate / 4 / Moderate waves, blocks of sheep everywhere
6 / Strong breeze / 9,9-12,4 / Wind begins to sing in the wires and rigging / Rough / 5 / Large waves, foam and spray
7 / Near gale / 12,5-15,2 / Very rough / 6 / Sea heads up, foam in streaks
8 / ветер Gale / 15,3-18,2 / It is difficult to walk a deck against the wind / Very rough / 7 / High waves, dense foam, spray impairs visibility
9 / Strong gale / 18,3-21,5 / High / 7
10 / Storm / 21,6-25,1 / Very high / 8 / Very high tumbling waves, surface white with foam, visibility affected
11 / Violent storm / 25,2-29,0 / Phenomenal / 9 / Exceptionally high
waves, sea covered in foam, air filled with spray and foam, visibility severely impaired
12 / Harricane / Более 29,0 / 9

Table 2

Beaufort scale to estimate wind force

Wind force / Word description / Wind speed / Wind impact on ship and rigging / Sea state
M/s / Km/h / knots
0 /
Calm / 0-0,2
(0) / 0-1
(0) / 0-1
(0) / Air is absolutely calm.
Smoke is vertical. Pendant is still / Calm glassy
1 / Light airs / 0,3-1,5
(1) / 1-5
(3) / 1-3
(2) / Light air is felt from time to time. Smoke inclines showing wind direction / Calm rippled
2 / Light breeze / 1,6-3,3
(3) / 6-11
(8) / 4-6
(5) / Continuous breeze. Flags and pendants slightly waver in the wind / Small wavelets
3 / Gentle
breeze / 3,4-5,4
(5) / 12-19
(15) / 7-10
(8) / Flags and pendants flap in the wind. Smoke is almost horizontal / Large wavelets, some breaking, glassy foam
4 / Moderate breeze / 5,5-7,9
(7) / 20-28
(24) / 11-16
(13) / Pendant is in a streak / Small waves, breaking, flocks of sheep here and there
5 / Fresh breeze / 8,0-10,7
(9) / 29-38
(33) / 17-21
(19) / Big flags flap in the wind and are instreaks. Wind moves small objects. / Moderate well-defined waves, flocks of sheep everywhere
6 / Strong breeze / 10,8-13,8
(12) / 39-49
(44) / 22-27
(25) / Wind begins to sing in the wires and rigging / Large waves, foam and spray.
7 / Near gale / 13,9-17,1
(15) / 50-61
(55) / 28-33
(31) / Wind sings in the wires and rigging. Some difficulties in walking a deck against the wind / Sea heads up, foam in streaks
8 / Gale / 17,2-207
(19) / 62-64
(68) / 34-40
(37) / Very difficult to walk a deck against the wind / Higher long waves, foam in streaks
9 / Strong gale / 20,8-24,4
(23) / 75-88
(81) / 41-47
(44) / Small damage to rigging is possible. Unfixed objects move. / High waves, dense foam, spray impairs visibility.
10 / Storm / 24,5-28,4
(27) / 89-102
(95) / 48-55
(51) / Considerable damage to rigging is possible / Very high tumbling waves, surface white with foam, visibility affected
11 / Violent storm / 28,5-32,6
(31) / 103-117
(110) / 56-63
(59) / Same / Exceptionally high waves, sea covered in foam, visibility severely impaired
12 / Harricane / Свыше
>33 / Свыше 117 / Свыше 63 / Severe damage / Air filled with spray and foam, visibility severely impaired

Code. Table 3. Sea Surface State (MS).

Number / Indicators to define sea surface state (number of wave degree).
0 / Sea surface is calm glassy
1 / Ripple; small wave crests appear.
2 / Small wave crests begin to break, however foam, which is generated, is not white but glassy.
3 / Small waves are clearly visible, crests of some of them break forming here and there white froth – flocks of sheep.
4 / Waves take a well-defined form, flocks of sheep are formed everywhere.
5 / Crests of considerable height appear wind begins to tear foam away from wave crests.
6 / Crests outline long streaks of wind waves.
7 / Long streaks of foam torn off by wind cover wave slopes and in places reach wave hollows.
8 / Wide streaks of foam cover wave slopes making sea surface white. Only here and there in wave troughs there are areas free of foam.
9 / Sea surface is covered with a thick layer of foam, air is full of water spray, and visibility is affected considerably.

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