465 
Deutsche Hydrographische Zeitschrift 
German Journal of Hydrography 
Volume 51 (1999) Number 4 
ISSN 0012-0308 
© BSH, Hamburg und Rostock 
Currents at the light-vessel "Deutsche Bucht": 
A comparison between ADCP measurements and 
the BSH forecast model 
Holger Klein, Stephan Dick 
Summary 
Between June 15 and August 10, 1999, an Acoustic Doppler Current Profiler (ADCP) and a water level 
recorder (WLR) were deployed in the close vicinity of the unmanned light-vessel "Deutsche Bucht" in the 
German Bight. Together with locally recorded meteorological and hydrographical data (salinity and tempera 
ture), this in-situ data set is compared to the forecasts of the BSH circulation model "BSHcmod". The meteo 
rological measurements are used to assess the meteorological model input generated by an atmospheric 
model of the German Weather Service. Generally, we observed a good agreement between in-situ and mo 
del data. Differences between measured and predicted currents were observed at the surface and at 
mid-depth. They were caused mainly by missing ADCP data within the first 3 metres under the surface and 
by the coarse vertical grid spacing of the model which prevents the representation of sharp vertical gradients. 
Strömungen am Feuerschiff "Deutsche Bucht": Ein Vergleich zwischen ADCP-Messungen und dem 
BSH Vorhersagemodell (Zusammenfassung) 
Vom 15. Juni bis zum 10. August 1999 wurden direkt am unbemannten Feuerschiff „Deutsche Bucht“ 
ein Akustischer Doppler-Strömungsprofiler (ADCP) und ein Hochseepegel ausgelegt. Zusammen mit vor Ort 
registrierten meteorologischen und hydrographischen Daten (Temperatur und Salzgehalt), wird dieser In-Si- 
tu Datensatz mit den Vorhersagen des BSH Zirkulationsmodells „BSHcmod“ verglichen. Die meteorologi 
schen Messungen werden benutzt, um den von einem Atmosphärenmodell des Deutschen Wetterdienstes 
berechneten atmosphärischen Input zu beurteilen. Generell stimmen gemessene und prognostizierte Strö 
mungen sehr gut überein. Beobachtete Abweichungen an der Oberfläche und auf halber Wassertiefe lassen 
sich durch fehlende ADCP-Daten direkt an der Wasseroberfläche und durch eine zu grobes vertikales Mo 
dellgitter erklären, das die Bildung von scharfen vertikalen Gradienten verhindert. 
1 Introduction 
The unmanned light-vessel "Deutsche Bucht", 
hereafter abbreviated UFS DB, is located about 
15 nm west of the island of Helgoland in the German 
Bight (see Fig. 3 c). From June 15, 1999, to August 
10, 1999, the Federal Maritime and Hydrographic 
Agency (Bundesamt fur Seeschiffahrt und Hydrog 
raphic, BSH) deployed an Acoustic Doppler Current 
Profiler (ADCP) and a water level recorder (WLR) in 
the close vicinity of the UFS DB (54° 10.75’ N, 
7° 27.34’ E) at a water depth of 38 m. The ADCP re 
corded the currents between 4 metres above the 
bottom (hereafter mab) and 4 m depth with a vertical 
resolution of 2 m. An automatic sampling station on 
board UFS DB transmits local weather data to the 
German Weather Service (Deutscher Wetterdienst, 
DWD) on an hourly basis. The BSH MARNET (Ma 
rine Environmental Monitoring Network in the North 
and Baltic Seas) station on board UFS DB samples 
temperature data at 3, 6, 10, 15, 20, 25, and 30 m 
depth, and salinity data at 6 and 30 m depth. These 
data are also transmitted hourly to the BSH via sat 
ellite. The transmitted values are averaged over the 
last 10 minutes preceding transmission. 
This in-situ data set, including local currents, 
sea level, temperature, salinity, and wind data, is 
compared to the results of the BSH operational cir