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

Peer reviewe

Effect of ice algal community on the increase of chlorophyll a concentration during spring in coastal water of the Sea of Okhotsk

A seasonal study of size fractionated chlorophyll α concentration was conducted weekly in Monbetsu Harbor from October 1996 to November 1997 to investigate the annually persistent occurrence of the spring peak of the chlorophyll α concentration in the >10μm size fraction immediately after the retreat of sea ice, as described by K. Hamasaki et al. (Plankton Biol. Ecol., 45,151,1998). Species composition of natural phytoplankton assemblages was also investigated to study whether phytoplankton or ice algae were responsible for the spring peak in the coastal water. The spring peak occurred immediately after the retreat of sea ice but timing of the occurrence was different between the stations occupied in the present study. The spatial heterogenity in occurrence of the spring peak seemed to be related to the sea ice distribution between the stations. New sea ice provided only a small supply of ice algae due to the relatively short growth period inside of the harbor. Large ice floes provided for a large supply of ice algae due to the long growth period outside of the harbor. The magnitude of the spring peak was related to sea ice growth. However, those ice algae seemed to sink to the bottom with little contribution to phytoplankton assemblage in the harbor, while ice algae contributed significantly to the spring peak outside of the harbor. Species composition revealed relatively fast response of phytoplankton to the environmental change after the disappearance of sea ice. Surface assemblages of phytoplankton including ice algae seemed to respond fully to the regional optical condition by changing in the species composition

Modelling experiments on air–snow–ice interactions over Kilpisjärvi, a lake in northern Finland

The evolution of snow and ice thicknesses and temperature in an Arctic lake was investigated using two models: a high-resolution, time-dependent model (HIGHTSI) and a quasi-steady two-layer model on top of a lake model (FLake). In situ observations and a Numerical Weather Prediction model (HIRLAM) were used for the forcing data. HIRLAM forecasts, after orography correction, were comparable with the in situ data. Both lake-ice models predicted the ice thickness (accuracy 5 cm), surface temperature (accuracy 2–3 °C in winter, better in spring), and ice-breakup date (accuracy better than five days) well. HIGHTSI was better for ice thickness and ice-breakup date, while FLake gave better freezing date. Snow thickness outcome was worse, in particular for the melting season. Surface temperature was highly sensitive to air temperature, stratification and albedo, and the largest errors (positively biased) resulted in strongly stable conditions

Measurements of snow depth and sea ice thickness by electromagnetic-induction measurements observed by Japan and Australia in the Antarctic Ocean.

第2回極域科学シンポジウム/第34回気水圏シンポジウム 11月17日（木） 統計数理研究所 セミナー室

Floating ice platform for winter observations in freezing lakes and coastal waters

An automatic observation float has been designed, tested and utilized for wintertime investigations in lakes and coastal waters. The float can be deployed in a lake during the open water season, so that it is capable to collect data continuously throughout the period of freeze-up and further on during the ice season. The float is anchored to the bottom so that it should be stable in the freeze-up period. The instrumentation includes a 2-m mast for measurements of the atmospheric boundary layer and radiation balance, thermistor strings and PAR sensors down from the water surface for measurements in ice and water, and an independently anchored current meter and CTD sensor. The float has been utilized in several lakes in Finland and in Santala Bay in the Baltic Sea in 1999–2011 with very good results. The data have been used for investigations of the lake heat fluxes, ice formation and melting, and light transfer in the snow–ice–water system. The data have also served as the calibration and validation data in the development of an advanced thermodynamic lake ice model including the layers of snow, slush, snow-ice and congelation ice. In addition, they have been utilized in the modelling the winter circulation in an ice-covered lake. This measurement system will be a suitable platform in further collaborative physical–biological investigations of freezing lakes and landfast ice in coastal regions.Session 1: Ice and Climate Chang

Influence of the ice-ocean heat flux on the ice thickness evolution in Saroma-ko lagoon, Hokkaido, Japan

Sea ice grows and decays as forced by the fluxes through the boundaries. In particular, the flux at the lower boundary -- the heat flux from the water body into the bottom of the ice sheet -- is not very well known quantity. A thermodynamic sea ice model is employed to examine the influence of the oceanic heat flux on the thickness of the ice. Saroma-ko ice station data is used to analyse the physics and calibrate the model. The oceanic heat flux is normally 5-10 W/m2, and the ice thickness ranges in 30-50 cm; being that thin, the ice has a very active role in the thermodynamics.16th International Northern Research Basins Symposium and Workshop. 27 August - 2 September 2007. Petrozavodsk, Russia

COMPARATIVE STUDY OF OCEANOGRAPHIC CHARACTERISTICS ABOVE/UNDER FIRST-YEAR SEA ICE AT LOW AND HIGH LATITUDES (16th Symposium on Polar Biology)

As part of the joint Japanese and Canadian scientific experiment, the SARES (Saroma-Resolute Studies) project, to study "the biological CO_2 pump under the first-year ice in the Arctic Ocean" and "the biological processes in Arctic polynya areas", meteorological and oceanographic studies were carried out successively at the Saroma Ko lagoon, Hokkaido, Japan from December 1991 to April 1992, and in Resolute Passage, Canadian Arctic from April to June 1992. Seasonal sea ice at its southern limit in the Sea of Okhotsk reaches a maximum thickness of about 40 cm at the Saroma Ko lagoon, while ice reaches a maximum thickness of about 2 m in Resolute Passage. In this paper, meteorological and oceanographic variables obtained from both field experiments of the SARES project are compared. The presence of sea ice cover leads to major changes in the flow and stratification regime. We observed much weaker currents and the presence of small scale vertical structure in the temperature-salinity regime under complete landfast ice covered areas. It is believed that ice melt and freshwater input from a small river played an important role in generating the observed variability in the lagoon. The presence/absence of sea ice plays a significant role in determining the oceanographic characteristics of the lagoon and its potential for biological productivity. It is believed that the difference in solar irradiance between low and high latitudes in seasonally sea-ice covered waters plays a significant role in biological productivity in the spring regime

Rapid physically driven inversion of the air-sea ice CO2 flux in the seasonal landfast ice off Barrow, Alaska after onset of surface melt

The air-sea ice CO2 flux was measured over landfast sea ice in the Chukchi Sea, off Barrow, Alaska in late May 2008 with a chamber technique. The ice cover transitioned from a cold early spring to a warm late spring state, with an increase in air temperature and incipient surface melt. During melt, brine salinity and brine dissolved inorganic carbon concentration (DIC) decreased from 67.3 to 18.7 and 3977.6 to 1163.5 μmol kg^[-1], respectively. In contrast, the salinity and DIC of under-ice water at depths of 3 and 5 m below the ice surface remained almost constant with average values of 32.4 ± 0.3 (standard deviation) and 2163.1 ± 16.8 μmol kg^[-1], respectively. The air-sea ice CO2 flux decreased from +0.7 to -1.0 mmol m^[-2] day^[-1] (where a positive value indicates CO2 being released to the atmosphere from the ice surface). During this early to late spring transition, brought on by surface melt, sea ice shifted from a source to a sink for atmospheric CO2, with a rapid decrease of brine DIC likely associated with a decrease in the partial pressure of CO2 of brine from a supersaturated to an undersaturated state compared to the atmosphere. Formation of superimposed ice coincident with melt was not sufficient to shut down ice-air gas exchange