MURSYS - North Sea and Baltic Sea - Report 2 2007





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MURSYS - North Sea and Baltic Sea - Report 2 2007

   
 
 

Marine Environmental Reporting System - Abstract - Reporting Period: 1 July - 31 December 2007

North Sea

Weather

July 2007 was the third consecutive month with warmer and weather conditions than usual. The monthly mean temperatures of 16 - 17 °C were 0.5 - 1 K above the long-term reference values (1961 - 1990). Almost daily rains led to 81 mm precipitation on Helgoland and 142 mm on the coasts of Lower Saxony, which corresponded to 130 - 190 % of the mean values. The duration of sunshine, at 160 - 200 hours, was mostly 10 - 20 % below normal. On the North Sea islands, the 200 - 220 hours of sunshine in July corresponded largely to the mean values. Gale force winds occurred occasionally during thunderstorms or rainstorms.
Monthly mean temperatures of 17 - 18 °C in August were about 1 K above the long-term means. Precipitation ranged mostly between 50 and 65 mm, or 10 - 30 % below the mean values, except for the the coast of Lower Saxony, where 75 - 90 mm of rain fell. The duration of sunshine, 170 - 213 hours, was up to 10 % below normal August mean values. Also in August, winds occasionally gusted up to gale force during thunderstorms or rainstorm.
The monthly mean temperatures of 14 - 15 °C in September were on the order of the reference values. Rainfall of 70 - 90 mm in most places deviated ±15 % from the mean values. The duration of sunshine, at 110 - 130 hours, was 10 - 20 % below the mean values (exception: North Frisian islands, with 150 hours of sunshine.) This month's highest wind speeds of 8 - 9 Bft were recorded in early and mid-September.
Although the weather in October was sunny and dry, its monthly mean temperatures of 9 - 11 °C were slightly lower than the long-term reference values. At 20 - 40  mm precipitation, less than half the normal quantity of rain fell in most places. 100 - 115 hours of sunshine were recorded, which was up to 20 % above normal. Weak winds prevailed.
November was too warm and dry, with monthly mean temperatures of 6 - 8 °C, which was up to 1 K above the long-term means. Precipitation varied within a wide range from 54 mm (Sylt) to 112 mm (Bremerhaven), bringing a surplus of 40 % in the area between Elbe and Weser and a deficit of up to 40 % in the other parts of the North Sea coast. With 30 - 35 hours of sunshine in East Friesland and nearly 80 hours in North Friesland, values were up to 40 % above or below normal. Strong NW winds occurred in the first half of the month and at the end of the month. Winds reaching hurricane force in gusts led to a severe storm surge on 9 November.
Monthly mean temperatures in December ranged from 3.5 °C in East Friesland to 5.6 °C on Helgoland, exceeding the long-term means by 1 - 2 K. The number of frost and ice days remained below average. Also precipitation, at 60 - 75 mm in most places, was up to 15 % below the monthly means. The duration of sunshine was 20 - 30 hours, which was 20 - 40 % less than normal. Gale-force gusts occurred in the first third of the month, and weak winds prevailed during the rest of the month.

Water temperatures

The monthly mean value of sea surface temperatures (SST) is compared to the so-called climatological value (1971 - 1993). The ranking among the highest SST monthly mean values since 1971 is given in brackets:

The monthly mean SST in July 2007 was 14.9 °C, which was 0.6 K above the climatological mean (rank 13 among the highest mean SST in July since 1971).
The mean SST in August was 15.5 °C, exceeding the climatological mean by 0.5 K (rank 16).
Also in September, the mean SST of 14.2 °C was 0.5 K above the climatological mean (rank 17).
The mean SST in October was 12.7 °C, exceeding the climatological mean by 0.8 K (rank 10).
SST in November averaged 10.6 °C, which was 1.0 K above the climatological mean (rank 7).
The monthly mean SST in Dezember was 8.5 °C, 0.7 K above the climatological mean.

Surface runoff

In the second half of 2007, Elbe runoff (Neu-Darchow gauge station) was below the runoff mean of the 1926 - 2004 reference period in July; runoff in August corresponded to the mean value, and in the last three months of 2007 the reference means were clearly exceeded (1 ½ fold or more).
Weser runoff (Intschede gauge station) throughout the second half of 2007 was clearly above the 1951 - 2004 reference means, with runoff in October and November more than twice as high.
In the second half of 2007, also the Ems runoff volume (Versen gauge station) exceeded the 1951 - 2004 reference means considerably: runoff in August was more than twice the mean value.
Runoff of the river Rhine (Rees gauge station) in October and November 2007 was slightly below the mean values of the 1931 - 2004 reference series. Runoff in the other months mostly exceeded the mean values noticeably.

Ice conditions

Also in the second half of 2007, there was no ice formation on the German North Sea coasts due to mild weather.

Baltic Sea

Weather

Monthly mean temperatures of 16 to 18 °C in July 2007 were up to 1 K above the long-term reference values (1961 - 1990). With monthly rainfall ranging from 100 to 120 mm, precipitation was 50 - 100 % above the mean values. The duration of sunshine, at 170 to 220 hours, was 10 to 30 % below normal.
Also in August, the mean monthly temperatures of 17 to 18 °C were 1 K above normal. Regional rainfall varied considerably, ranging between 70 and 110 mm in most places, which was about 150 - 200 % of the long-term mean. 190 to 216 hours of sunshine were recorded, which was 10 to 20 % lower than normal. During rainstorms and thunderstorms, winds occasionally gusted up to gale force.
Weather conditions in September were unsteady, with mean temperatures of 13 - 14 °C, corresponding to the long-term means. Precipitation of 50 to 75 mm exceeded the mean values by up to 40 %. The duration of sunshine was only 130 - 140 hours, 10 - 20 % less than the long-term mean. Low pressure systems brought on stronger north-westerly winds which reached 8 to 10 Bft in the middle of the month and in late September.
October started out sunny and dry, with monthly mean temperatures of 9 - 10 °C corresponding to the long-term means. In the second half of the month, up to 4 days of frost were recorded. Total rainfall in October was only 20 - 40 mm, or 50 - 100 % of mean values. 110 to 120 (Kap Arkona: 137) hours of sunshine were recorded in most places, up to 20 % above normal.
In November, monthly mean temperatures generally were on the order of the long-term means, at 4 to 6 °C. Only 40 to 50 mm precipitation, rain mixed occasionally with snow, was recorded in most areas, which was up to 20 % below normal. The sun shone 55 to 70 hours, exceeding normal monthly values by up to 30 %. Gale-force winds were recorded on some days.
December, with little sunshine and monthly mean temperatures of 3 - 4 °C, was 1 - 2 K too warm. There were 2 - 10 frost days and 1 - 3 ice days. At 40 - 55 mm precipitation, the long-term means were exceeded by up to 20 %. The duration of sunshine was low, at 10 - 20 hours, which was 40 - 50 % of the long-term mean. Strong to gale-force winds occurred in the first ten days of the month.

Water temperatures

Water temperatures (at a depth of 3 m) on the coast of Mecklenburg-Vorpommern off Warnemünde and Koserow in July 2007 averaged 17.8 °C and 18.0 °C, respectively, which was on the order of the reference series (1997 to 2007 in Warnemünde; 1999 to 2007 in Koserow).
Also in August, the mean water temperatures off Warnemünde, at 17.2 °C, and off Koserow, at 19.0 °C, corresponded to the reference series.
In September, water temperatures of 15.1 and 15.6 °C, respectively, on average were up to 1 K below the values of the reference series.
Mean water temperatures in October reached 12.9 and 12.3 °C, respectively, corresponding to the reference series.
That was also the case in November, when mean water temperatures of 8.1 °C were measured off Warnemünde, and 7.2 °C off Koserow.
Water temperatures in December averaged 5.6 and 4.6 °C, respectively, which was slightly higher than the values of the reference series.

Water levels

Water levels on the Baltic coasts of Schleswig-Holstein and Mecklenburg-Vorpommern reached monthly mean values in July 2007 which were 11 cm (Kiel) and 7 cm (Koserow) above the values of the reference series (1991 to 2000 in Schleswig-Holstein; 1996 to 2005 in Mecklenburg-Vorpommern). Extreme values of the month were the minimum water level of 466 cm recorded in Flensburg on 27 July, and the maximum level of 553 cm measured in Eckernförde on 16 July.
In August, the recorded mean water levels in Kiel were 10 cm, and in Koserow 9 cm above the reference series. The lowest water level was recorded in Flensburg on 17 August, at 469 cm, and the highest levels of 595 cm and 577 cm were measured in Lübeck and Wismar, respectively, on 21 August.
The mean water levels in September were 15 cm (Kiel) and 19 cm (Warnemünde) above the values of the reference series. On 28 September, water levels in many places reached the warning level of 600 cm, with the maximum value of 639 cm recorded in Schleswig. The lowest value of 460 cm was measured in Eckernförde on 2 September.
Monthly mean water levels in October were 15 cm (Travemünde) and 10 cm (Warnemünde) above the values of the reference series. The flood event of 12 October led to maximum levels of 615 cm in Flensburg, and 612 cm in Wismar, on 13 October. The lowest water level of 439 cm was recorded in Flensburg on 12 October.
Also in November, the mean water levels exceeded the values of the reference series, in Travemünde by 8 cm, and in Warnemünde by 14 cm. The highest levels were measured at the Lübeck and Greifswald gauge stations on 14 November, at 599 cm and 595 cm, respectively. The lowest water level of 409 cm was measured in Flensburg on 25 November.
Mean water levels in December exceeded the values of the reference series by 7 cm (at Travemünde and Warnemünde). The maximum level of 571 cm was recorded in Greifswald on12 December, the minimum value of 430 cm in Wismar on 28 December.

Surface runoff

Runoff volumes of the river Odra (Hohensaaten-Finow gauge station) in July and August 2007 were markedly below the runoff means of the 1941 - 2004 reference series. Runoff in September and October was on the order of the reference series, and slightly exceeded the long-term means in November and December.

Ice conditions

First ice in the 2007/08 ice season formed in mid-November in the innermost part of the northern Bottenvik skerries - about one week later than normal - and in the easternmost part of the Gulf of Finland - which was about 10 days earlier than normal. From the beginning of December 2007, ice formation was repeatedly interrupted by mild weather, so that the extent of ice formation in the northern Baltic remained very limited.

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