A model measurements comparison of atmospheric forcing and surface fluxes of the Baltic Sea

Observed basic meteorological quantities, heat and radiation fluxes from three different measurement stations in the Baltic Sea are compared with model data of the coupled sea-ice-ocean model BSIOM in order to evaluate the atmospheric forcing, corresponding surface fluxes and the sea surface response. Observational data were made available from the BASIS winter campaigns in 1998 and 2001 as well as from the r/v "Alkor" cruise in June 2001. Simulated fluxes were calculated from prescribed atmospheric forcing provided from the SMHI meteorological database and modelled sea surface temperatures. The comparison of these fluxes with observations demonstrates a strong correlation, even though mean differences in sensible heat fluxes range from 4 to 12 W m-2 in winter and -25 W m-2 in the June experiment. Differences in latent heat fluxes range from -10 to 23 W m-2. The short-wave radiation flux used as model forcing is on average 15 W m-2 less than the corresponding observations for the winter experiments and 40 W m-2 for the June experiment. Differences in net long-wave radiation fluxes range from -5 to 12 W m-2 in winter and -62 W m-2 for the June experiment. The correspondence between measured and calculated momentum fluxes is very high, which confirms the usability of our model component for calculating surface winds and wind stresses from the atmospheric surface pressure

IR-Renormalon Contributions to the Structure Functions g3g_3 and g5g_5

We calculate the leading $1/N_f$ perturbative contributions to the polarized nonsinglet structure functions $g_3$ and $g_5$ to all orders in $\alpha_s$. The contributions from the first renormalon pole are determined. It is a measure for the ambiguity of the perturbative calculation and is assumed to dominate the power corrections. The corrections $\Delta g_3$ and $\Delta g_5$ are given as functions of the Bjorken variable $x$ and turn out to be negligable. The anomalous dimensions of the leading twist operators are obtained in the next-to-leading order.Comment: 12 pages, 4 eps-figure

Dynamic features of successive upwelling events in the Baltic Sea - a numerical case study

Coastal upwelling often reveals itself during the thermal stratification season as an abrupt sea surface temperature (SST) drop. Its intensity depends not only on the magnitude of an upwelling-favourable wind impulse but also on the temperature stratification of the water column during the initial stage of the event. When a "chain" of upwelling events is taking place, one event may play a part in forming the initial stratification for the next one; consequently, SST may drop significantly even with a reduced wind impulse. Two upwelling events were simulated on the Polish coast in August 1996 using a three-dimensional, baroclinic prognostic model. The model results proved to be in good agreement with in situ observations and satellite data. Comparison of the simulated upwelling events show that the first one required a wind impulse of 28000 kg m-1 s-1 to reach its mature, full form, whereas an impulse of only 7500 kg m-1 s-1 was sufficient to bring about a significant drop in SST at the end of the second event. In practical applications like operational modelling, the initial stratification conditions prior to an upwelling event should be described with care in order to be able to simulate the coming event with very good accuracy

A methodology for knowledge acquisition through literature: Building knowledge-based systems for strategic management

In this paper a methodology designed for knowledge acquisition through literature is presented. It mainly fits strategic business problems, but is also applicable in domains with similar characteristics. In contrast to other methodologies that use documents in textual forms, this approach tries to incorporate public knowledge to a large extent. In several subsequent steps this knowledge is elicited, documented, evaluated and formalized. The result of this methodology is a formalized and structured knowledge document that is well-prepared for implementation in a rule-based KBS. Emphasis is laid on problems concerning the evaluation and interpretation of the content rather than on technical problems arising in this context. Implementation, testing and verification of the knowledge base are subsequent stages to occur after knowledge acquisition and are not described within this paper

Correlation analyses of Baltic Sea winter water mass formation and its impact on secondary and tertiary production

The thermal stratification of the upper water layers in the Baltic Sea varies seasonally in response to the annual cycle of solar heating and wind-induced mixing. In winter, the stratification down to the halocline is almost completely eroded by convection and strong wind mixing. Monthly averaged temperature profiles obtained from the ICES hydrographic database were used to study the long-term variability (1950 to 2005) of winter water mass formation in different deep basins of the Baltic Sea east of the island of Bornholm. Besides strong interannual variability of deep winter water temperatures, the last two decades show a positive trend (increase of 1-1.5°C). Correlations of winter surface temperatures to temperatures of the winter water body located directly above or within the top of the halocline were strongly positive until the autumn months. Such a close coupling allows sea surface temperatures in winter to be used to forecast the seasonal development of the thermal signature in deeper layers with a high degree of confidence. The most significant impact of winter sea surface temperatures on the thermal signature in this depth range can be assigned to February/March. Stronger solar heating during spring and summer results in thermal stratification of the water column leading to a complete decoupling of surface and deep winter water temperatures. Based on laboratory experiments, temperature-dependent relationships were utilised to analyse interannual variations of biological processes with special emphasis on the upper trophic levels (e.g., stage-specific developmental rates of zooplankton and survival rates of fish eggs)

CAVIAR: Climate variability of the Baltic Sea area and the response of the general circulation of the Baltic Sea to climate variability

The warming trend for the entire globe (1850-2005) is 0.04°C per decade. A specific warming period started around 1980 and continues at least until 2005, with a temperature increase of about 0.17°C per decade. This trend is equally well evident for many areas on the globe, especially on the northern hemisphere in observations and climate simulations. For the Baltic Sea catchment, which lies between maritime temperate and continental sub-Arctic climate zones, an even stronger warming of about 0.4°C per decade appeared since 1980. The annual mean air temperature increased by about 1°C until 2004. A similar warming trend could be observed for the sea surface temperature of the Baltic Sea. Even the annual mean water temperatures averaged spatially and vertically for the deep basins of the Baltic Sea show similar trends. We provide a detailed analysis of the climate variability and associated changes in the Baltic Sea catchment area as well as in the Baltic Sea itself for the period 1958-2009, in which the recent acceleration of the climate warming happened. Changes in the atmospheric conditions causes corresponding changes in the Baltic Sea, not only for temperature and salinity but also for currents and circulation. These changes in the physical conditions have strong impact on the marine ecosystem structure and processes