Fourth Study Conference on BALTEX Scala Cinema Gudhjem

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- 80 - Evaluation of Atmosphere - Ocean Heat Fluxes over the Baltic Sea Using a Number of Gridded Meteorological Databases Anna Rutgersson 1 , Anders Omstedt 2 and Gabriella Nilsson 1 1 Department of Earth Science, Meteorology, Uppsala University, Uppsala, Sweden, anna.rutgersson@met.uu.se 2 Department of Earth Science, Oceanography, Göteborg University, Göteborg, Sweden. 1. Introduction The water cycle and energy budget for the Baltic Sea have been evaluated and analysed in a number of investigations. Still, different methods give different results depending on the method used and the time period of interest. Estimated net-precipitation (precipitation minus evaporation) over the Baltic Sea usually is between 1500 and 2000 m 3 s -1 with an estimated bias of about 1000 m 3 s -1 (Meier and Döscher 2002; Rutgersson et al., 2002). Net heat exchange was in Omstedt and Rutgersson (2001) shown to be 1 Wm -2 and thus the Baltic Sea thermodynamically behaves like a lake. As data are being more refined and accurate the estimates of parameters like net precipitation and net heat exchange have the possibility of being more certain. In this investigation we are using a number of gridded meteorological databases to evaluate differences in surface heat fluxes and to give some errorbars in the determination of the Baltic Sea energy budget. We are using Re-Analysis data from the ECMWF (ERA40) and the gridded data-base SMHI(1×1)˚, available from the BALTEX Hydrological Data Centre. The data have been evaluated for limited periods using in-situ measurements from the island of Östergarnsholm in the Baltic Sea as well modelled data based on Baltic Sea ocean modelling. Also gridded fluxes from satellite-derived data is used. 2. Methods In the ECMWF Re-Analysis project (ERA), observational data is assimilated using the ECMWF operational global model (http://www.ecmwf.int/research/era). For this project all available observational data is used, including satellite data, synoptic data, ship and buoy data as well as other sources. The data used in the present investigation (ERA40) covers the time-period 1958 to 2002. The ERA40-data is used in a number of applications, forcing regional- and meso-scale models as well as making climate statistics. Thus it is of great importance to know the accuracy for various regions. ERA40 data is evaluated using in-situ measurements from one site in the Baltic Sea. The meteorological measurements are taken at the small very flat island of Östergarnsholm, about 4 km east of Gotland. The data include slow meteorological measurements as well as turbulence data. In Smedman et al. (1999) further information on the measurements is found. The analysed period is from 1995 too 2002 and all available data are used to give relatively good coverage over different seasons and situations. Both mean meteorological parameters (as temperature, windsspeed and humidity) and turbulent fluxes are analysed for this period. Using a system with an ocean model forced with synoptic data SMHI(1×1)˚ (see Rutgersson et al, 2001) gives a consistent system with information of both mean meteorological parameters, sea surface data and surface fluxes. SMHI(1×1)˚ is a gridded synoptic database using 700-800 daily observations in the Nordic region. These are interpolated in space using optimum interpolation and used to force the ocean process-oriented model PROBE- Baltic covering the Baltic Sea (Omstedt and Axell, 2003). Also satellite-based (Graßl et al., 2000) and ship-based (daSilva et al., 1994) gridded fluxes are used for the evaluation. In the Hamburg Ocean Atmosphere Paramters and Fluxes from Satellite Data (HOAPS) a number of satellite-derived parameters covering the entire globe is available for the period July 1987 to December 1998. Monthly, seasonal and annual fields are available and also possibly higher temporal and spatial resolution (http://www.mpimet.mpg.de/Depts/Physik /HOAPS). 3. Results The presentation will cover analyses of atmosphere-ocean heat fluxes and implication on the BALTEX heat budget. Evaluation of specific parameters in the ERA40 database will be shown, using the other data-sources. Figure 1. Latent (a) and sensible (b) heat fluxes from direct measurements at the site Östergarnsholm (blue crosses) and calculated with the ocean model forced with the SMHI(1×1)˚ data base (red lines). Time period is days of October 1998. In Figure 1 sensible and latent heat fluxes from a Baltic Sea ocean model forced with SMHI(1×1)˚ data base are shown for October 1998. The agreement with the directly measured fluxes from the Östergarnsholm site is relatively good. Figure 2 shows monthly averages of sensible and latent heat flux for the period 1988 to 1997 for satellite-derived data from HOAPS and the ocean model forced with SMHI(1×1)˚ the data are averages over the entire Baltic Sea.
Figure 2. Monhly mean values of latent (a) and sensible (b) heat flux for the Baltic Sea from HOAPS (green circles) and the ocean model forced with SMHI(1×1)˚ data (blue stars). Error-bars show one standard deviation of the variability. HOAPS give larger values of the latent heat fluxes during summer and fall and lower values of the sensible heat flux during fall and winter. The differences are significant and of the order of 20 Wm -2 as monthly averages. References Da Silva, A., Young, C. C. and Levitus, C., Atlas of Surface Marine Data 1994 Vol. 1. Algoritms and Procedures, NOAA Atlas NESDIS 6, U.S. Dept. of Commerce, Washington D.C., 83 pp., 1994 Graßl, H., Jost, V., Kumar, R., Schulz, J., Bauer, P., and Schlüssel, P., The Hamburg ocean-atmosphere parameters and fluxes from satellite data (HOAPS): A climatological atlas of satellite derived air-seainteraction parameters over the oceans, Max-Plack- Institut für Meteorologie, Rep. No. 312, 130 pp., 2000 Meier, H. E. M. and Döscher, R., Simulated water and heat cycles of the Baltic Sea using a 3D coupled atmosphereice-ocean model, Boreal Environ. Res., 7, 327-334, 2002 Omstedt, A. and L., Axell. Modeling the variations of salinity and temperature in the large Gulfs of the Baltic Sea. Continental Shelf Research, 23, 265-294, 2003 Omstedt, A. and A. Rutgersson. Closing the Water and Heat Cycle of the Baltic Sea. Meteorol. Z., 9, 57-64 Rutgersson, A., Smedman, A. and Omstedt, A., Measured and simulated latent and sensible heat fluxes at two marine sites in the Baltic Sea, Boundary- Layer Meteorol., 99, 53-84, 2001 Rutgersson, A. A. Omstedt and J. Räisänen, Net precipitation over the Baltic Sea during present and future climate conditions, Climate Research., 22, 27-39, 2002 Smedman, A., Högström, U., Bergström, H., Rutgersson, A., Kahma, K., and H. Pettersson, A case-study of air-sea interaction during swell conditions, J. Geophys. Res, 104, 25,833-25,851, 1999 - 81 -
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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
Page 45 and 46: shows a ground-track of the vessel
Page 47 and 48: - 31 - Determination and Comparison
Page 49 and 50: - 33 - Spatial Variability of Snow
Page 51 and 52: - 35 - EVA-GRIPS: Regional Evaporat
Page 53 and 54: - 37 - LITFASS-2003 - A Land Surfac
Page 55 and 56: -39- Calibrated Surface Temperature
Page 57 and 58: - 41 - The Marine Boundary Layer -
Page 59 and 60: - 43 - Characteristics of the Atmos
Page 61 and 62: Figure 2. Surface stress from two d
Page 63 and 64: During the experiment the water was
Page 65 and 66: While the number of smallest drops
Page 67 and 68: SCANDIA will not be supported any l
Page 69 and 70: - 53 - Relationships Between Precip
Page 71 and 72: - 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: 1 0.8 0.6 0.4 0.2 GO(CLD-M) ERA40 S
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 and 124: - 107 - Validation of Boundary Laye
Page 125 and 126: - 109 - Simulated Dynamical Process
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
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- 131 - Wind Energy Prognoses for t
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- 133 - Detection of Climate Change
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Figure 3. Cross section of salinity
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of 35 m/s up to 3 hours. Data on wi
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Figure 2. Time series of Mean Sea L
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- 141 - Calculation and Forecast of
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- 143 - An Overview of Long-Term Ti
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- 145 - Baltic Sea Saltwater Inflow
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- 147 - Significance of Feedback in
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Lindström, G., Johansson, B., Pers
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- 151 - Air-Sea Fluxes Including Mo
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- 153 - The Realism of the ECHAM5.2
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- 155 - Figure 3. Accumulated total
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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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