N. G. Platonov

Duration of the Arctic Sea Ice Melt Season: Regional and Interannual Variability, 1979-2001

Abstract Melt onset dates, freeze onset dates, and melt season duration were estimated over Arctic sea ice, 1979–2001, using passive microwave satellite imagery and surface air temperature data. Sea ice melt duration for the entire Northern Hemisphere varied from a 104-day minimum in 1983 and 1996 to a 124-day maximum in 1989. Ranges in melt duration were highest in peripheral seas, numbering 32, 42, 44, and 51 days in the Laptev, Barents-Kara, East Siberian, and Chukchi Seas, respectively. In the Arctic Ocean, average melt duration varied from a 75-day minimum in 1987 to a 103-day maximum in 1989. On average, melt onset in annual ice began 10.6 days earlier than perennial ice, and freeze onset in perennial ice commenced 18.4 days earlier than annual ice. Average annual melt dates, freeze dates, and melt durations in annual ice were significantly correlated with seasonal strength of the Arctic Oscillation (AO). Following high-index AO winters (January–March), spring melt tended to be earlier and autumn fr...

Fluctuating Arctic Sea Ice Thickness Changes Estimated by an In Situ Learned and Empirically Forced Neural Network Model

Abstract Sea ice thickness (SIT) is a key parameter of scientific interest because understanding the natural spatiotemporal variability of ice thickness is critical for improving global climate models. In this paper, changes in Arctic SIT during 1982–2003 are examined using a neural network (NN) algorithm trained with in situ submarine ice draft and surface drilling data. For each month of the study period, the NN individually estimated SIT of each ice-covered pixel (25-km resolution) based on seven geophysical parameters (four shortwave and longwave radiative fluxes, surface air temperature, ice drift velocity, and ice divergence/convergence) that were cumulatively summed at each monthly position along the pixel’s previous 3-yr drift track (or less if the ice was <3 yr old). Average January SIT increased during 1982–88 in most regions of the Arctic (+7.6 ± 0.9 cm yr−1), decreased through 1996 Arctic-wide (−6.1 ± 1.2 cm yr−1), then modestly increased through 2003 mostly in the central Arctic (+2.1 ± 0.6 c...

The possibility of using high resolution satellite images for detection of marine mammals

The possibility of using modern systems of remote sensing in the optical range from high spatial resolution satellites for detection of marine mammals and traces of their activity is investigated. An image obtained by the GeoEye satellite within the FEAC project was used for the analysis. The image covers Herald Island and adjacent waters, which are a part of the Wrangel Island Reserve, during the seasonal thaw (June 2009). It is shown that marine mammals (polar bears, walruses, and whales) can be identified on such images. The absence of synchronous ground truth observations reduces the reliability of the results.

Seropositivity for different pathogens in polar bears (Ursus maritimus) from Barents Sea Islands

Analysis of serum prevalence of antibodies to six pathogens was performed in 26 polar bears from the Barents Sea population. Animals seropositive for the viruses of pseudorabies, canine distemper, and influenza A, Dirofilaria sp., Trichinella spiralis, and Toxoplasma gondii were revealed, with prevalence of antibodies to T. spiralis being the highest. Most of them were adult bears, while cubs (under 1 year of age) proved to be seronegative for all pathogens.

Distribution of beluga whales ( Delphinapterus leucas ) in the Russian Arctic seas according to the results of expedition aboard RV Mikhail Somov, September–November 2010

Data on the distribution of marine mammals, including beluga whales (Delphinapterus leucas Pallas, 1766), in the Arctic are scarce because of various causes and conditions, including the vast expanses of the region, its poor accessibility, severe climate, long polar night, and high cost of research. Nevertheless, the results of aerial observations during ice reconnaissance and onboard observations during sea voyages (Kleinenberg et al., 1964; Geptner et al., 1976; Belikov, Boltunov, and Gorbunov, 2002; Belikov and Boltunov, 2002; Ezhov, 2005; Matishov and Ognetov, 2006; Biologiya i okeanografiya…, 2007; Lukin and Ognetov, 2009) have provided a general idea of the distribution pattern of beluga whales in the Russian Arctic seas. More detailed data concern the distribution of these whales in the White Sea, where aerial surveys of the water area were performed previously and have been resumed in recent years (Nazarenko et al., 2008; Glazov et al., 2010, 2011). The relevant data on the Barents, Kara, Laptev, and East Siberian seas are much poorer. In the summer (ice-free) period, beluga whales concentrate in coastal waters. They have been recorded most frequently off Franz Josef Land, Novaya Zemlya, Vaygach Island, and in Czech Bay in the Barents Sea; in Baydaratskaya Bay, Gulf of Ob, and Yenisei Gulf in the Kara Sea; off the northeastern coast of Taimyr and in estuaries of the Anabar, Olenyok, and Lena rivers in the Laptev Sea; and in the estuaries of the Indigirka (where the whales come from the west) and the Kolyma and Ked’ma rivers (where they come from the east) in the East Siberian Sea. The amount of information obtained in other seasons is very limited. In autumn, mass migration of beluga whales from the Kara Sea to the Barents Sea have been recorded in the Karskie Vorota Strait and off Cape Zhelaniya in the north of Novaya Zemlya. In winter, almost no records of these whales have been made in the Kara, Laptev, and East Siberian seas. These data are based on previous observations and have practically not been complemented in recent years.

Evaluation of polar bear movement patterns in relation to sea ice drift

191 The polar bear inhabits mainly the Arctic sea ice, where it moves and hunts. The study of polar bear movements aimed mostly at determining the bear sea sonal habitats [1] and evaluating the size of its home ranges [2]. However, the ice where the polar bear lives is drifting, and the ice drift have a substantial influence on the trajectory of animal relocations. The sea ice motion has been earlier assessed only qualitatively, but the rate and direction of sea ice drift should be mea sured quantitatively to evaluate correctly the animal movements on ice. A technique of quantitative mea surement has been elaborated in this study.

Movements of polar bear females (Ursus maritimus) during an ice-free period in the fall of 2011 on Alexandra Land Island (Franz Josef Land Archipelago) using satellite telemetry

The behavior of female polar bears with cubs in an isolated terrestrial area of Alexandra Land Island (Franz Josef Land Archipelago) was analyzed in the fall of 2011 in an ice-free period using Argos satellite telemetry and the data of ground observations. The size and structure of their home ranges and selection of their habitats have been estimated; the differences in behavior of tagged animals have been analyzed.

Observations of the Walrus (Odobenus rosmarus) in the Barents, Kara, and Laptev Seas in 2010-2012

Data on walrus (Odobenus rosmarus) sightings during four scheduled cruises of the research expedition vessel Mikhail Somov in the Barents, Kara, and Laptev seas (August–November, 2010; September–October, 2011; November–December 2011; and July–October, 2012) and during an expedition on the Polyaris motor ship in August–September, 2012, are presented. The data collected support and expand the existing knowledge on the distribution and abundance of the Atlantic and Laptev walrus subspecies.

Analysis of the Arctic sea ice conditions for 2011 at the onset of summer minimum

The summer minimum of the Arctic sea ice area and extent have been estimated for 2011 using satellite passive microwave data. Compared with sea ice conditions during the satellite era (1979 to the present), the Arctic ice cap is close in size to the absolute minimum recorded in 2007. However, the spatial distribution of sea ice at the end of summer differed in 2007 and 2011 due to the atmospheric circulation effect on the position of the ice edge. It is shown that the decreasing rate of the ice cover has increased fourfold since 2003. A linear model has been developed for the global short-term prediction of Arctic ice conditions and historical reconstruction (until the middle of the 20th century, including the pre-satellite era) of summer ice conditions from the air temperature fields using the dimensionality reduction technique (principal component analysis) and canonical correlation analysis. The simulation results confirm the drastic change in the sea ice area at the end of summer after 2002.

Isotopic Composition of Blood of Polar Bears (Ursus maritimus) of the Kara–Barents Sea Population

The data on the content of carbon and nitrogen isotopes in the blood samples of polar bears obtained in the present study confirm that polar bears in the Taimyr region (and the Kara–Barents sea population in general) are partly dependent on the resources of terrestrial origin. However the “terrestrial carbon” evidently reaches bears’ tissues indirectly, via marine food webs utilizing organic carbon brought into the polar basin by Siberian rivers.