Fourth Study Conference on BALTEX Scala Cinema Gudhjem

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- 108 - Upwelling in the Baltic Sea - A Numerical Model Case <strong>Study</strong> Andreas Lehmann and Hans-Harald Hinrichsen Institute for Marine Sciences Kiel, alehmann@ifm-geomar.de 1. Introduction Up- and downwelling are typical phenomena in the Baltic Sea. Because of the complex coastline and many islands, wind from any direction causes up- and downwelling near the coast. The extent of upwelling is scaled by the internal Rossby radius which is about 2-10 km in the Baltic Sea. During summer and autumn when the sea surface is warm, upwelling can be observed as a local temperature drop of several degrees by infrared satellite measurements (Gidhagen, 1987). Cold water from below the thermocline is lifted upwards and eventually reaches the surface, where it replaces a well-mixed and considerably warmer upper layer. Upwelling is forced by sudden storms or strong wind events form different directions, with typical time scales ranging from a few days up to week. Satellite data indicate that the horizontal scales of coastal upwelling are of the order of 100 km alongshore and some 10-20 km in the direction out from the coast. Sometimes upwelled water is spread several tens of kilometers out into the basin, forming filaments of cold water (Gidhagen, 1987). Different upwelling events occurring in 1997 have been analyzed and compared. Satellite images have been used to identify strong upwelling along the coast and to estimate the proper temporal range as well as the extent of the affected area. The different upwelling events have been further analyzed by utilizing modeling results of a coupled sea iceocean model run for 1997. From the numerical model simulation the upwelling process can be analyzed in detail and the corresponding volume transports along and offshore the coast can be determined, thus quantifying coastal upwelling. To distinguish the effects of upwelling from other processes, a numerical model case study has been performed. Different experiments have been carried out where a sudden constant wind affects the Baltic Sea for one week. Then the wind was switched off and the experiments lasted three more weeks. 2. Numerical model case study To separate the upwelling process from other processes 11 experiments were carried out, where the Baltic Sea response to different constant wind forcing was analyzed. Figure 1 shows the anomaly of the sea level along the coast of the Baltic Sea. The course starts in the Mecklenburg Bight and ends in the southern Kattegat. For the first week constant wind of 10 m/s from the north was specified. After seven days, the wind was switched off and the experiment lasted three more weeks. Because of the sudden onset of the wind seiches were excited. In case of upwelling the sea level drops along the coast (coast of Baltic Countries), for downwelling an increase of sea surface height occurs. Figure 1. Anomaly of sea level along the coast of the Baltic Sea. When the wind vanishes the sea level returns to zero elevation. A quantification of alongshore and offshore transports have been performed for the different experiments. Generally in the Central Baltic Sea, highest alongshore transport for the near surface waters result when winds are mainly directed off- or onshore, while alongshore transport below the near surface layers is lower in magnitude and often is into the opposite direction. If winds are more orientated along the coasts, the alongshore transports have the tendency to be vertically more uniform distributed and are associated with upwelling events if the coast is located to the left hand side of the wind direction and vice versa. Strongest off- and onshore currents in the surface layers are mainly due to Ekman transports with the main wind component parallel to the coast. Generally, the flow below the surface layers are directed into opposite direction to compensate the surface currents. References Gidhagen, L., Coastal upwelling in the Baltic Sea - Satellite and in situ Measurements of sea surface temperatures indicating coastal upwelling, Estuarine , Coastal Shelf Science, 24., 449-462, 1987.
- 109 - Simulated Dynamical Processes in the South Baltic from a Coupled Ice - Ocean Model Robert Osinski Institute of Oceaology Polish Academy of Sciences Powstancow Warszawy 55, 81-712 Sopot, Poland Roberto@iopan.gda.pl 1. Abstract A three dimensional z-coordinate model is used to investigate the water circulation as well as the heat and water transports in the southern Baltic. The model is based on the Bryan-Cox-Semtner model with a horizontal resolution of about 9km and 21 vertical levels. The presentation shows details of simulation strategies and discusses the results of the model. Computed values are compared with measurements done by Institute of Oceanology Polish Academy of Sciences.
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Fourth Stu
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Preface The 4 th Study</str
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- I - Table of Abstracts Title Auth
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- III - Sensitivity in Calculation
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- V - Parameter Estimation of the S
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- VII - The Realism of the ECHAM5.2
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Adam, W. K. .......................
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- 1 - Activities of the GEWEX Hydro
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eference site archive (Cabauw, Neth
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- 5 - Remote Sensing of Atmospheric
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minute averages around the satellit
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- 9 - Precipitation Type Statistics
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- 11 - Assimilation of New Land Sur
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Multichannel Microwave Radiometer f
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output has been processed in an equ
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height dependence of the Z-R-relati
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- 19 - CERES and Surface Radiation
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- 21 - Coastal Wind Mapping from Sa
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- 23 - Clouds and Water Vapor over
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- 25 - Broadband Cloud Albedo from
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- 27 - Observation of Clouds and Wa
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shows a ground-track of the vessel
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- 31 - Determination and Comparison
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- 33 - Spatial Variability of Snow
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- 35 - EVA-GRIPS: Regional Evaporat
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- 37 - LITFASS-2003 - A Land Surfac
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-39- Calibrated Surface Temperature
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- 41 - The Marine Boundary Layer -
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- 43 - Characteristics of the Atmos
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Figure 2. Surface stress from two d
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During the experiment the water was
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While the number of smallest drops
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SCANDIA will not be supported any l
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- 53 - Relationships Between Precip
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- 55 - Analysis of the Role of Atmo
Page 73 and 74: - 57 - Meteorological Peculiarities
Page 75 and 76: Baltic Sea Inflow Events Jan Piechu
Page 77 and 78: - 61 - The Different Baltic Inflows
Page 79 and 80: - 63 - Observations of Turbulent Ki
Page 81 and 82: - 65 - The Influence of Synoptic Si
Page 83 and 84: -67- Improved Method for the Determ
Page 85 and 86: -69- The Helicopter-Borne Turbulenc
Page 87 and 88: - 71 - CEOP Reference Site Data fro
Page 89 and 90: - 73 - The BALTEX Hydrological Data
Page 91 and 92: - 75 - Hydrological and Hydrochemic
Page 93 and 94: -77- Sea-level Monitoring at MARNET
Page 95 and 96: 1 0.8 0.6 0.4 0.2 GO(CLD-M) ERA40 S
Page 97 and 98: Figure 2. Monhly mean values of lat
Page 99 and 100: In the case of an ideal fit, the co
Page 101 and 102: - 85 - Influence of Atmospheric For
Page 103 and 104: The largest inter-annual variabilit
Page 105 and 106: References Andrejev, O, Sokolov, A.
Page 107 and 108: On the other hand, if the stratific
Page 109 and 110: Cyberska 1989, Cyberska and Krzymin
Page 111 and 112: - 95 - Continental-Scale Water-Bala
Page 113 and 114: - 97 - ICTS (Inter-CSE Transferabil
Page 115 and 116: The subsurface flow calculation is
Page 117 and 118: functions only data with higher qua
Page 119 and 120: - 103 - Modelling the Impact of Ine
Page 121 and 122: - 105 - Objective Calibration of th
Page 123: - 107 - Validation of Boundary Laye
Page 127 and 128: spreads along isobaths (fig.2). As
Page 129 and 130: than the precipitation pattern of J
Page 131 and 132: Figure 2. Long-term variability in
Page 133 and 134: obvious from temperature charts. Ho
Page 135 and 136: shortening of the winter seasons by
Page 137 and 138: Maximum 5 day precipitation (mm) Nu
Page 139 and 140: scale parameters the correlation be
Page 141 and 142: similar: the locations of main mini
Page 143 and 144: - 127 - Storminess on the Western C
Page 145 and 146: - 129 - Trends in Wind Speed over t
Page 147 and 148: - 131 - Wind Energy Prognoses for t
Page 149 and 150: - 133 - Detection of Climate Change
Page 151 and 152: Figure 3. Cross section of salinity
Page 153 and 154: of 35 m/s up to 3 hours. Data on wi
Page 155 and 156: Figure 2. Time series of Mean Sea L
Page 157 and 158: - 141 - Calculation and Forecast of
Page 159 and 160: - 143 - An Overview of Long-Term Ti
Page 161 and 162: - 145 - Baltic Sea Saltwater Inflow
Page 163 and 164: - 147 - Significance of Feedback in
Page 165 and 166: Lindström, G., Johansson, B., Pers
Page 167 and 168: - 151 - Air-Sea Fluxes Including Mo
Page 169 and 170: - 153 - The Realism of the ECHAM5.2
Page 171 and 172: - 155 - Figure 3. Accumulated total
Page 173 and 174: Figure 2. Example for Fourier decom
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Figure1. Modeled percent volume cha
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conditions even more challenging th
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surface heat fluxes close to zero.
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- 165 - Figure 1. Modeled seasonal
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- 167 - Present-Day and Future Prec
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- 169 - Extreme Precipitation on a
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at the stations Pärnu (Estonia) an
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6. Results There are many possible
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and vegetation, and to derive the h
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The structure of water bodies cadas
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Figure 1. The area of Gdańsk subje
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- 181 - Climate and Water Resources
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- 183 - Generating Synthetic Daily
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The evapotranspiration is affected
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Model parameters and coefficients:
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3. Hydrodynamic model of nutrient l
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No. 15: Minutes of 8 th Meeting of
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Fourth Study Conference on BALTEX Scala Cinema Gudhjem

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