Irina Repina

Tracing Atlantic Water Signature in the Arctic Sea Ice Cover East of Svalbard

We focus on the Arctic Ocean between Svalbard and Franz Joseph Land in order to elucidate the possible role of Atlantic water (AW) inflow in shaping ice conditions. Ice conditions substantially affect the temperature regime of the Spitsbergen archipelago, particularly in winter. We test the hypothesis that intensive vertical mixing at the upper AW boundary releases substantial heat upwards that eventually reaches the under-ice water layer, thinning the ice cover. We examine spatial and temporal variation of ice concentration against time series of wind, air temperature, and AW temperature. Analysis of 1979–2011 ice properties revealed a general tendency of decreasing ice concentration that commenced after the mid-1990s. AW temperature time series in Fram Strait feature a monotonic increase after the mid-1990s, consistent with shrinking ice cover. Ice thins due to increased sensible heat flux from AW; ice erosion from below allows wind and local currents to more effectively break ice. The winter spatial pattern of sea ice concentration is collocated with patterns of surface heat flux anomalies. Winter minimum sea ice thickness occurs in the ice pack interior above the AW path, clearly indicating AW influence on ice thickness. Our study indicates that in the AW inflow region heat flux from the ocean reduces the ice thickness.

Arctic Ocean Heat Impact on Regional Ice Decay: A Suggested Positive Feedback

AbstractBroad, long-living, ice-free areas in midwinter northeast of Svalbard between 2011 and 2014 are investigated. The formation of these persistent and reemerging anomalies is linked, hypothetically, with the increased seasonality of Arctic sea ice cover, enabling an enhanced influence of oceanic heat on sea ice and, in particular, heat transported by Atlantic Water. The “memory” of ice-depleted conditions in summer is transferred to the fall season through excess heat content in the upper mixed layer, which in turn transfers to midwinter via thinner and younger ice. This thinner ice is more fragile and mobile, thus facilitating the formation of polynyas and leads. When openings in ice cover form along the Atlantic Water pathway, weak density stratification at the mixed layer base supports the development of thermohaline convection, which further entrains warm and salty water from deeper layers. Convection-induced upward heat flux from the Atlantic layer retards ice formation, either keeping ice thick...

Wind Climate in Kongsfjorden, Svalbard, and Attribution of Leading Wind Driving Mechanisms through Turbulence-Resolving Simulations

This paper presents analysis of wind climate of the Kongsfjorden-Kongsvegen valley, Svalbard. The Kongsfjorden-Kongsvegen valley is relatively densely covered with meteorological observations, which facilitate joint statistical analysis of the turbulent surface layer structure and the structure of the higher atmospheric layers. Wind direction diagrams reveal strong wind channeled in the surface layer up to 300 m to 500 m. The probability analysis links strong wind channeling and cold temperature anomalies in the surface layer. To explain these links, previous studies suggested the katabatic wind flow mechanism as the leading driver responsible for the observed wind climatology. In this paper, idealized turbulence-resolving simulations are used to distinct between different wind driving mechanisms. The simulations were performed with the real surface topography at resolution of about 60 m. These simulations resolve the obstacle-induced turbulence and the turbulence in the non-stratified boundary layer core. The simulations suggest the leading roles of the thermal land-sea breeze circulation and the mechanical wind channeling in the modulation of the valley winds. The characteristic signatures of the developed down-slope gravity-accelerated flow, that is, the katabatic wind, were found to be of lesser significance under typical meteorological conditions in the valley.

The analysis of results of remote sensing monitoring of the temperature profile in lower atmosphere in Bergen (Norway)

Considered is the application of MTP-5 meteorological temperature profiler used for the remote sensing of vertical profiles of the air temperature in the planetary boundary layer and the lower one-kilometer layer of the atmosphere. The measurements were carried out in Bergen (Norway) in 2011–2012. The obtained dataset of temperature profiles has temporal resolution of five minutes and vertical resolution of 50 m. The MTP-5 data are complemented with the measurements of the air temperature and the wind taken at two automatic weather stations and with the measurements of the rain intensity made with the rain radar. Studied is the impact of meteorological conditions and precipitation on the MTP-5 readings. It is revealed that formation of a thin water film (of ice or, to a smaller degree, of sleet) on the surface of the sensor cover of MTP-5 has a significant impact on the data of the temperature monitoring. The removal of intensive precipitation (the precipitation rate is >0.2 mm/hour) improved the reliability and quality of the temperature profile monitoring. In particular, it is demonstrated that significant air pollution and stably stratified atmospheric conditions which lead to low temperatures are reliably monitored with this instrument.

Summer school on board an Arctic icebreaker

It has been reported widely that the climate in the Arctic is changing rapidly, maybe faster there than anywhere else. In addition, northern sea ice is shrinking, especially in the coastal seas of the Russian Arctic, such as the Laptev Sea. Since 2002, the International Arctic Research Center (IARC), based at the University of Alaska Fairbanks, has been recording long-term oceanographic observations in this region through the Nansen and Amundsen Basins Observation System (NABOS) project. In 2005, the annual NABOS expedition was conducted in parallel with a summer school on board the icebreaker Kapitan Dranitsyn. This was the third IARC-supported summer school.Two previous summer schools were held in Fairbanks. A total of 24 university students and early career scientists had been chosen, out of about 140 summer school applicants: six from the United States, five from Russia, five from Canada, two from Norway and one each from Belgium, Denmark, France, Germany, New Zealand, and Sweden.Vladimir Alexeev of IARC, the author of this meeting report, served as the director of the school; Louis Fortier of Laval University (Quebec City, Canada) was co-director.

Comparison of calculated and measured CO2 fluxes between the ocean and atmosphere in the southwestern part of the East Siberia Sea

The interaction between the degradation of land and underwater permafrost, which is a storage of enormous resources of organic matter [1, 2], and the emission of the final product of its decomposition ( CO 2 ) into the atmosphere is of special interest in global warming manifested most strongly in the Arctic region. Insufficient attention has been paid thus far to investigation of the carbonate system in the seas of the Eastern Arctic with the widest and shallowest shelf in the World Ocean. Previously, it was commonly accepted that the Arctic seas serve as sinks of atmospheric CO 2 [3] in the summer‐autumn period due to low water temperature and high seasonal productivity. However, our previous investigations demonstrated that the southwestern part of the East Siberia Sea (ESS) is an important source of carbon dioxide for the atmosphere in summer. It is assumed that high partial CO 2 pressure is formed due to the influence of the river discharge and destruction of labile organic matter transported to seawater as a result of the destruction of the coastal ice complex [2‐6]. Up to the present time, there is no commonly accepted opinion about the preference of applying one or another method for calculating CO 2 fluxes in the ocean‐atmosphere system, in particular, in the polar regions. Based on the study of the ESS, this work presents the first results of the comparison of calculated values obtained by different algorithms with the fluxes measured by the micrometeorological method. The optimal method for calculating the CO 2 fluxes in the ocean‐atmosphere system is chosen for the study region. This work is based on the materials of the expedition in the southwestern ESS in September 2005 (Fig. 1). In these expeditions, CO 2 fluxes between the ocean and the atmosphere in the eastern arctic region were measured synchronously and calculated for the first time. The methods of measurements and calculation of elements of the carbonate system and the CO 2 fluxes between seawater and the atmosphere are described in detail in [5]. The mean CO 2 concentration in the atmosphere (372 µ atm), hourly and daily mean wind velocities ( U ) at a height of 10 m, and quadratic and cubic dependence of gas transport ( k ) on wind velocity were used in the calculations [7, 8]. The peculiarities of the micrometeorological method of measuring CO 2 fluxes are described in [6, 9].

Numerical modeling of the influence of cool skin on the heat balance and thermal regime of a water body

The influence that cool skin has on the energy exchange between the atmosphere and the ocean is investigated in this work. For this purpose, a series of numerical experiments with the use of the one-dimensional LAKE model of a water body were performed. Three types of cold-skin parameterization were used in this model. The data of in situ measurements in the coastal zone of the Black Sea, in the Arctic Ocean, and over Lake Sparkling served as the boundary and initial conditions. It has been established from the results of experiments that the LAKE model with the incorporated parameterization of the cool skin successfully reproduces cold-skin characteristics, namely, the difference between the temperature of the cool skin surface and the water temperature below the skin. The results of numerical experiments are within the variability of the results of in situ measurements. It has been shown that the presence of a cool skin reduces the heat losses of a body of water. The numerical experiments showed that the presence of a cool skin can change the thermal regime of a water body and its stratification by changing the heat balance at the surface. This result can be important for the modeling of many processes inside a body of water and at its surface, for example, gas and heat exchange.

Field studies of variation scales of gravitational capillary waves and near-water wind in the Black Sea shelf area

In this study we present the results of data processing from the 2004 Gelendzhik Bay expedition on the Akvanavt research vessel. The data were processed using the method of wavelet analysis. We found an emerging kilometer-scale variation in the surface heaving and near-water wave over the shelf area. This effect was shown to be possibly caused by the inhomogeneity of current in the depth-drop area.

Air-sea interaction monitoring by remote and contact measurements: The results of the CAPMOS’05 and CAPMOS’07 experiments on an oceanographic platform in the Black Sea

The paper presents the results of the experiments CAPMOSpsila05 and CAPMOSpsila07 performed on an offshore oceanographic platform in the Black Sea. The platform equipped with contact and remote sensors is located approximately 600 m to the south of Crimea coast, Ukraine. The experiments aimed at air-sea interaction monitoring were carried out by an international research team during summer months in 2005 and 2007. Spectral parameters of wind and waves were estimated from direct and remote measurements. A comparison with known spectrum models was performed.

Subsatellite experiments in the north-eastern part of the Black Sea

Space-time variability of current field characteristics, surface waves, and parameters of the near-surface atmospheric layer above the shelf zone of the Black Sea in the Gelendzhik-city region are studied. A joint analysis of the field measurement data obtained on August, 2007, September, 2008 and of the synchronous SAR images made by the Envisat satellite of the European Space Agency is carried out.