Land–ice interaction in the Baltic Sea

An overview of the evolution of landfast ice in the Baltic Sea, especially in the vicinity of Hailuoto Island in the north, is given, and semi-analytical models are presented to examine the vertical and lateral growth and breakage of landfast ice. The outer edge of landfast ice moves further offshore as the ice becomes thicker. Occasionally, landfast ice breaks and moves, forming grounded ridges, scouring the sea bottom, piling up on the shore and riding up onto land up to distances of more than 100 m. According to observations of ice breakage, the yield strength of landfast ice is proportional to the squared ice thickness. In very shallow areas the water may freeze to the bottom, and after sea level rise the ice may drift away and transport bottom sediment. The models provide a first-order approach to understand the evolution of the landfast ice zone from the start to the winter maximum

The brine and gas content of sea ice with attention to low salinities and high temperatures

Based on the well known sea ice phase diagram, equations are derived for determining the brine and gas content of sea Ice for high temperatures (range 0 to -2 °C) and low salinities. The presently widely used equations of Cox and Weeks (1982) are valid only for temperatures below -2°C. Fresh-water ice is used as a boundary condition for the equations. The relative salt concentrations in brine are_assumed to be the same as in normal (or standard) seawater. Two sets of equations are presented: 1) accurate formulae based on UNESCO standard sea water equations, and 2) approximate formulae based on general properties of weak solutions. The approximate formulae are not essentially different from the classical system which basically assumes the freezing point to be a linear function of fractional salt content. The agreement between the two approaches is excellent and the approximate system is good enough for most applications

Kymijoen jääolosuhteet ja veden laatu

In this paper we will present results from field measurements at the River Kymijoki gathered during winter 2011/2012. River Kymijoki research project was started in fall 2011 and these results are part of the results that were made for master’s thesis of Tom Kokkonen. River Kymijoki is located in southeast Finland, it freezes annually, and the catchment area of the river is 37 107 km2 which is about 11 % of the area of Finland. The lake percentage of the river catchment is 19 %. Aim of this first stage of the research project was to select measurement points and evaluate their suitability to present the River Kymijoki ice and water quality phenomena. Other goal for the project was to examine the collected data and process a comprehensive image of the River Kymijoki ice phenomena and water quality.Non peer reviewe

Ice Phenology in Eurasian Lakes over Spatial Location and Altitude

Eurasian freezing lakes cover an almost 180° wide longitude sector between the latitudes 30° and 75° N, and their altitudes range from below the sea surface level up to 5 km elevation. Ice phenology varies widely in this region. However, these variations and their influence factors have been little studied. Analytic models are applied here to examine these variations supported by historical ice and weather data. These models are forced by a linear air–lake heat exchange formula based on local empirical fits. The weather brings latitude–longitude–altitude patterns to the large-scale lake ice phenology. Freezing and breakup dates are forced by the local air temperature and solar radiation, and their rates of change are also important. In addition, freezing depends on lake depth and breakup depends on accumulated ice thickness. Lake depth provides a lag and radiation balance provides a shift with respect to the air temperature in cooling of the lake, and breakup is dictated by spring warming conditions and ice thickness. Due to solar radiation forcing, the common degree-day approach is biased for modelling ice phenology, especially in low latitudes. Analytic models provide a first-order tool for climate sensitivity of ice seasons. The freezing date and breakup date both change by around five days per one-degree shift in air temperature away from the climatological ice margin; however, at this margin, the sensitivity is higher

Ice Phenology in Eurasian Lakes over Spatial Location and Altitude

Eurasian freezing lakes cover an almost 180° wide longitude sector between the latitudes 30° and 75° N, and their altitudes range from below the sea surface level up to 5 km elevation. Ice phenology varies widely in this region. However, these variations and their influence factors have been little studied. Analytic models are applied here to examine these variations supported by historical ice and weather data. These models are forced by a linear air–lake heat exchange formula based on local empirical fits. The weather brings latitude–longitude–altitude patterns to the large-scale lake ice phenology. Freezing and breakup dates are forced by the local air temperature and solar radiation, and their rates of change are also important. In addition, freezing depends on lake depth and breakup depends on accumulated ice thickness. Lake depth provides a lag and radiation balance provides a shift with respect to the air temperature in cooling of the lake, and breakup is dictated by spring warming conditions and ice thickness. Due to solar radiation forcing, the common degree-day approach is biased for modelling ice phenology, especially in low latitudes. Analytic models provide a first-order tool for climate sensitivity of ice seasons. The freezing date and breakup date both change by around five days per one-degree shift in air temperature away from the climatological ice margin; however, at this margin, the sensitivity is higher

On the structure and mechanics of pack ice in the Bothnian Bay

Julkaisu sisältää myös seuraavat artikkelit: Kahma Kimmo K.: On two-peaked wave spectra Rinne Ilkka, Melvasalo Terttu, Niemi Åke, Niemistö Lauri: Studies on nitrogen fixation in the Gulf of Bothnia Barbaro Alvise, Francescon Antonia, Polo Bruno: Fluoride distribution along chlorinity gradients in Baltic Sea waters Andersin Ann-Britt, Sandler Henrik: Comparison of the sampling efficiency of two van Veen crab

Interannual variability and trends in winter weather and snow conditions in Finnish Lapland

The interannual variability of the air temperature, precipitation and snow conditions were examined in the Finnish Arctic region based on data from the period 1946-2012. The purpose of this work was to describe the climatology of the region and to examine long-term variations in the climatic parameters. This information is essential for both environmental and socioeconomic aspects of the Finnish Arctic region. The air temperature, precipitation and snow depth records from nine weather stations were analysed in order to study the evolution of the winter duration (sub-zero temperature days), precipitation, snow cover duration and snow depth. The climatological description was based on the most recent 30-year period record available (1982-2011). Since 1946, air temperature has increased significantly by 0.4 degrees C/decade. Significant precipitation trends reached up to 35 mm/decade. For the most part there were no significant trends in snow depth and snow cover duration.Peer reviewe

Seasonal and annual heat budgets offshore the Hanko Peninsula, Gulf of Finland

Peer reviewe

Evolution of snow cover and dynamics of atmospheric deposits in the snow in the Antarctica. Data report

Field programme on the surface layer of the ice sheet in the Dronning Maud Land, Antarctica has been performed in 2009-2011. The objectives were to examine the annual accumulation and sublimation history, snow melting, chemistry of snow impurities, and life history of supraglacial and epiglacial lakes in blue ice regions. Fieldwork was done during FINNARP 2009 and 2010 expeditions. The sites were at the Finnish research station Aboa (73 02.5'S, 013 24.4'W), a snow line from Rampen at the edge of the ice shelf pass Aboa to the station Svea, and blue ice at Basen and neighboring nunataks. Snow measurements were made using classical snow pit method, ice and snow sampling, and with automatic observation stations (surface radiation balance, penetration of sunlight into snow and ice, and temperature within the surface layer of snow and ice). Life history, physics, and ecological state of lakes were mapped. This document is the data report including a brief project introduction, descriptions of the experiments, and the data obtained