Baltic Sea

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• Model data from MOM4/IOW model, 2006 - 2009: MOM4/IOW Model data with a high horizontal resolution of 1 nautical mile (nm) covering the whole Baltic Sea. In this study: 5-day mean values of temperature, salinity and currents for three transects in the Stolpe Channel (54.9 − 55.7 ◦ N,17.5 ◦ E), the Gdansk Basin (55 ◦ N, 18.4 − 19.9 ◦ E) and Hoburg Channel (56 ◦ N, 18.2 − 19.6 ◦ E) between 2002 − 2009. Hourly values for Stolpe Channel (54.9 − 55.7 ◦ N, 16 − 18 ◦ E) between June 2006 and June 2007. 2.2 Analysis of observational data 2.2.1 Hydrographical data Measurements of temperature, T, salinity, S, oxygen, O 2 and depth, D, are regularly carried out by the Leibniz Institute for Baltic Sea Research Warnemuende (IOW) under the umbrella of the Baltic Monitoring Programme (COMBINE) of the Helsinki Commission (HELCOM). Resulting CTD data sets between 1968 − 1998 and 2006 were used to describe the overall hydrographic regime at the central station BMP271 (57 ◦ 19.2 ′ N, 20 ◦ 3.0 ′ E, see Fig. 1.2). This position roughly coincides with that of the former Baltic Year station BY-15A. Here, the water depth is about 242 m (Hagen and Feistel, 2001), and hydrographic proles were available ve times per year. Sampling followed the standard guidelines for the COMBINE programme at standard depths, and is considered to be representative for the description of trends in the hydrographic regime of the whole Baltic Proper (Fig. 1.1). This data set illustrates that the seasonal variability of deep water stratication parameters is relatively small. Consequently, most of the overall deep T-S proles are found to be in a narrow range, compared to the surface water variability. This made it possible to calculate an average prole characterizing thermohaline properties between the upper halocline (60 m) and 225 m depth (see Fig. 3.2. Beyond these single-point measurements, spatial CTD data from the MESODYN project were evaluated. Two campaigns were carried out in August/ September 1997 (M-7), and in April 1998 (M-8), i.e. just before and at the end of the warm inow event, respectively. Data for M-7 were obtained on a 13 × 16 station grid sampled from 29 August to 04 September 1997. CTD proles for M-8 were obtained on a coinciding grid from 19 − 24 April 1998, except 16
for the southernmost zonal section that was not sampled due to severe weather conditions. Available for our analysis were therefore 208 CTD stations from the M-7 survey and 195 CTD stations from the M-8 survey (see Fig. 1.2). Both eld campaigns started in the northwest and followed zonal transects towards the southern deep basin. In each case, the station spacing was 2.5 nm (4.6 km). This was sucient to resolve eddy-like patterns of the mass eld larger than about 9 km, smaller eddies cannot be resolved. The internal Rossby radius is therefore marginally resolved but for even smaller features aliasing eects have to be expected. Note that the two grid stations closest to the central station BMP271 were formally identied with BMP271 to increase the temporal resolution in the centre of the basin (see Fig. 1.2). Data acquisition and validation procedures are described in more detail by Hagen and Feistel (2001). Potential temperature, θ, and potential density, σ θ , were computed according to the thermodynamical relations suggested by Feistel and Hagen (1995) with the required reference level placed at the sea surface. Finally, all vertical proles were low-pass ltered with a 3 m running window in order to suppress high-frequency noise, and to avoid aliasing errors. For the 2006/07 study within the RAGO (tiefe RAndströme im östlichen Gotlandbecken der Ostsee, English: deep boundary currents in the Eastern Gotland Basin of the Baltic Sea) project, two diagonal CTD transects with 13 CTD proles each were carried out. The rst transect went from northeast to southwest on 26 − 27 September 2006 and the other transect went from northwest to southeast on 27 − 28 September 2006. The stations were chosen from the MESODYN project's grid and both transects had a spacing of around 3.5 nm, shown as a dotted cross in Fig. 1.1. These transects provided a snapshot of the hydrographic situation in the EGB and were then compared to data from the central monitoring station (BMP271), the model data and also to the temperature data from the three moorings to complete the general picture. The two CTD transect across the Stolpe Channel carried out on the 22 and 29 September 2006 were also rst established and part of the MESODYN project described in detail by Reissmann (1999), Reiÿmann (2002) and Reissmann (2006). From the transects with its 11 CTD stations (marked as dotted line in Fig. 1.1) and a station spacing of 2.5 nm not only 17
Page 1 and 2: No 88 2012 Spatiotemporal Scales of
Page 3 and 4: Meereswissenschaftliche Berichte MA
Page 5 and 6: Abstract The Baltic Sea is surround
Page 7 and 8: Contents Abstract Contents List of
Page 9 and 10: Acknowledgement 109 Appendix 111 vi
Page 11 and 12: M-7/M-8 Mesodyn hydrographic snapsh
Page 13 and 14: List of Figures 1.1 Baltic Sea - ba
Page 15 and 16: 4.32 Regression sea level dierence
Page 17 and 18: 1. Introduction 1.1 Investigations
Page 19 and 20: circulation above topographic anks
Page 21 and 22: 58 o N 190 230 210 100 75 100 100 7
Page 23 and 24: y 'new' deep water. For instance, i
Page 25 and 26: events. During and after such event
Page 27 and 28: this inow event was classied as 'mo
Page 29 and 30: Scale (PSS-78), roughly by 0.5%, as
Page 31: (Acoustic Doppler Current Proler) a
Page 35 and 36: whereas the length of the NE time s
Page 37 and 38: have a thickness of only 1.5 m in o
Page 39 and 40: dependent salt volumes for the deep
Page 41 and 42: 7 6.5 a Temperature ( o C) 6 5.5 5
Page 43 and 44: Potential Temperature ( o C) 8 7 6
Page 45 and 46: inowing waters masses with variable
Page 47 and 48: following these bounds will be used
Page 49 and 50: 60 80 100 −45 −50 −55 Pressur
Page 51 and 52: Monitoring Station BMP271 60 80 100
Page 53 and 54: Date 31.8.1997, 03.11.1997, 03.11.1
Page 55 and 56: 190 a 200 Depth (m) 210 220 230 240
Page 57 and 58: Date (ID) 〈S〉 V (g/kg) 〈θ〉
Page 59 and 60: deviation of the temperature uctuat
Page 61 and 62: 4. The Deep Circulation in the EGB
Page 63 and 64: Depth (m) 50 100 150 200 17 16 4.6
Page 65 and 66: For this reason, the displayed temp
Page 67 and 68: 6.4 6.3 178 m 208 m 223 m Daily Tem
Page 69 and 70: The deep parts of the basin are exp
Page 71 and 72: On the 29 September 2006 between 60
Page 73 and 74: In the geostrophic balance horizont
Page 75 and 76: captured eastward velocities up to
Page 77 and 78: Figure 4.11: Modelled current veloc
Page 79 and 80: SFS and SFN. At the southern ank a
Page 81 and 82: Mean Volume Transports Mean Volume
Page 83 and 84:
160 170 180 Volume of EGB below 170
Page 85 and 86:
Basin 55.9 ◦ N. From there the bo
Page 87 and 88:
Volume transports (km 3 /d) 15 10 5
Page 89 and 90:
Gdansk Basin happened a few weeks e
Page 91 and 92:
needs some explanation, since the l
Page 93 and 94:
and Fig. 4.24 and displayed in Tabl
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Salt (t) 8 6 4 2 0 2 4 6 8 x 10 10
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Time Period Stolpe Channel at 17.5
Page 99 and 100:
Modelled volume transport through S
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discovered that most of the varianc
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to the right (perpendicular) to the
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of salty and often well oxygenated
Page 107 and 108:
Depth (m) 40 45 50 55 60 4 3 2 1 0
Page 109 and 110:
a correlation coecient of R=-0.68 a
Page 111 and 112:
5. Discussion and Conclusions 5.1 D
Page 113 and 114:
graphic cross-sections, conducted i
Page 115 and 116:
direction as the wind. The deep lay
Page 117 and 118:
Bibliography Axell, L. B., 1998: On
Page 119 and 120:
Griffies, S. M., R. C. Pacanowski,
Page 121 and 122:
Matthäus, W., 1993: Major inows of
Page 123 and 124:
Rubio, A., D. Gomis, G. Jordà and
Page 125 and 126:
Zhurbas, V., I. Oh and V. Paka, 200
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Appendix Current speed and directio
Page 129 and 130:
Current speed and direction (cm/s)
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2 1.5 1 Cumulative volume through S
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Volume (km 3 ) 2.5 2 1.5 1 0.5 0
Page 135 and 136:
10 3 Regional Wind 7 Power Spectra
Page 137 and 138:
NE along−slope at 178m 10 2 10 1
Page 139 and 140:
Meereswissenschaftliche Berichte MA
Page 141 and 142:
26 (1997) Lakaschus, Sönke: Konzen
Page 143 and 144:
51 (2002) Wasmund, Norbert; Pollehn
Page 145 and 146:
78 (2009) Wasmund, Norbert; Pollehn
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