Coastal Polynya Disrupts the Acoustic Backscatter Diurnal Signal Over the Eastern Laptev Sea Shelf

The diel vertical migration (DVM) of zooplankton is one of the largest species migrations to occur globally and is a key driver of regional ecosystems and the marine carbon pump. The dramatic changes in the Arctic environment in recent years, mainly associated with sea-ice decline, may have wide significance for the Arctic shelf ecosystems including DVM. Observations have revealed the occurrence of DVM in ice-covered Arctic waters, however, there have yet to be observations of DVM from the extensive Siberian shelves in the Eurasian Arctic and no analysis of how the sea-ice decline may affect DVM. Here, 2 yearlong time series of acoustic backscatter, collected by moored acoustic Doppler current profilers in the eastern Laptev Sea from August 1998 to August 1999, were used to examine the annual cycle of acoustic scattering, and therefore the annual cycle of DVM in the area. The acoustic time series were used along with atmospheric and oceanic reanalysis and satellite data. Our observations show that DVM did not occur during polar night and polar day, but is active during the spring and fall transition periods when there is a diurnal cycle in light conditions. DVM began beneath the fast ice at the end of polar night and increased in intensity through spring. However, the formation of a large polynya along the landfast ice edge in late March 1999 caused DVM to abruptly cease near the fast ice edge, while DVM persisted through spring to the start of polar day at the onshore mooring. We associate this cessation of synchronized DVM ∼1 month ahead of polar day with a predator-avoidance behavior of zooplankton in response to higher polar cod abundance near the polynya. During polar day, the intensity of acoustic scattering was attributed to the riverine suspended particles. Overall, our results highlight the occurrence of DVM on the Siberian shelves, the cessation of synchronized DVM when a polynya opens up nearby, and the potential impact of significant trends toward a more extensive Laptev Sea polynya as part of changing ice conditions in the Eurasian Arctic and their impact on the Arctic shelf ecology.

Linking extreme seasonality and gene expression in arctic marine protists

At high latitudes, strong seasonal differences in light availability affect marine organisms and restrict the timing of ecosystem processes. Marine protists are key players in Arctic aquatic ecosystems, yet little is known about their ecological roles over yearly cycles. This is especially true for the dark polar night period, which up until recently was assumed to be devoid of biological activity. A 12 million transcripts catalogue was built from 0.45-10 μm protist assemblages sampled over 13 months in a time series station in an arctic fjord in Svalbard. Community gene expression was correlated with seasonality, with light as the main driving factor. Transcript diversity and evenness were higher during polar night compared to polar day. Light-dependent functions had higher relative expression during polar day, except phototransduction. 64% of the most expressed genes could not be functionally annotated, yet up to 78% were identified in arctic samples from Tara Oceans, suggesting that arctic marine assemblages are distinct from those from other oceans. Our study increases understanding of the links between extreme seasonality and biological processes in pico- and nanoplanktonic protists. Our results set the ground for future monitoring studies investigating the seasonal impact of climate change on the communities of microbial eukaryotes in the High Arctic.

Using electronic application for monitoring animals in protected areas on the example survey 123

Monitoring of the animal world is an important component in the development of world science. Observations of animals in specially protected nature areas are conducted year-round. The goal of the study was to develop electronic data collection forms for Survey123 used for ArcGIS application and to collect field data using this application tested during the field seasons 2018–2019 in the National Park Russian Arctic. Monitoring of the number of Arctic animals (white bears, walruses, seals, etc.) was carried out from the marine vessel and along the walking routes during the polar day by the state inspectors of the Russian Arctic National Park. The results of the application testing were the animal counting field data in electronic format taken during one flight of the 50 Years of Victory icebreaker, on the vessel “Altai” and during three flights of the Sea Spirit vessel. The total number of mammals obtained using the application during the 2018–2019 field seasons was 3,452 individuals, and the total number of birds was 14,457. All animal encounters are referenced by coordinates and presented on the electronic map. The Survey123 application testing during the 2018–2019 field seasons showed the efficiency of collecting animal data in electronic format which makes the data immediately available for processing and analysis. At the end of the field seasons, it was concluded that the electronic application can completely replace the hand-written register of animals.

Body Temperature and Activity Rhythms Under Different Photoperiods in High Arctic Svalbard ptarmigan (Lagopus muta hyperborea)

Organisms use circadian rhythms to anticipate and exploit daily environmental oscillations. While circadian rhythms are of clear importance for inhabitants of tropic and temperate latitudes, its role for permanent residents of the polar regions is less well understood. The high Arctic Svalbard ptarmigan shows behavioral rhythmicity in presence of light-dark cycles but is arrhythmic during the polar day and polar night. This has been suggested to be an adaptation to the unique light environment of the Arctic. In this study, we examined regulatory aspects of the circadian control system in the Svalbard ptarmigan by recording core body temperature (Tb) alongside locomotor activity in captive birds under different photoperiods. We show that Tb and activity are rhythmic with a 24-h period under short (SP; L:D 6:18) and long photoperiod (LP; L:D 16:8). Under constant light and constant darkness, rhythmicity in Tb attenuates and activity shows signs of ultradian rhythmicity. Birds under SP also showed a rise in Tb preceding the light-on signal and any rise in activity, which proves that the light-on signal can be anticipated, most likely by a circadian system.

Solar tracker with optical feedback and continuous rotation

Solar trackers are often used by spectrometers to measure atmospheric trace gas concentrations using direct sun spectroscopy. The ideal solar tracker should be sufficiently accurate, highly reliable, and with a longevity that exceeds the lifetime of the spectrometer that it serves. It should also be affordable, easy to use, and not too complex should maintenance be required. In this paper we present a design that fulfils these requirements using some simple innovations. Our altitude–azimuth design features a custom coaxial power transformer, enabling continuous 360∘ azimuth rotation. This increases reliability and avoids the need to reverse the tracker each day. In polar regions, measurements can continue uninterrupted through the summer polar day. Tracking accuracy is enhanced using a simple optical feedback technique that adjusts error offset variables while monitoring the edges of a focused solar image with four photodiodes. Control electronics are modular, and our software is written in Python, running as a web server on a recycled laptop with a Linux operating system. Over a period of 11 years we have assembled four such trackers. These are in use at Lauder (45∘ S), New Zealand, and Arrival Heights (78∘ S), Antarctica, achieving a history of good reliability even in polar conditions. Tracker accuracy is analysed regularly and can routinely produce a pointing accuracy of 0.02∘.

Near-perihelion activity of comet 67P/Churyumov–Gerasimenko. A first attempt of non-static analysis

ABSTRACT The observed rate of water production of comet 67P/Churyumov–Gerasimenko near its perihelion can be approximated by a very steep power function of the heliocentric distance. Widely used thermophysical models based on a static dust layer on top of the icy/refractory matrix are poorly consistent with these observations. We analyse published model results and demonstrate that thermophysical models with a uniform and static ice free layer do not reproduce the observed steep water production rates of 67P near perihelion. Based on transient thermal modeling we conclude that the accelerated gas activity can be explained assuming that the active area fraction near the south pole is increased. The deeper penetration of the heat wave during polar day (no sunset) can activate sublimation through thicker inert dust layers. This can also lead to removal of thicker dust layers and consequently to an expansion of the active area.

ABOUT THE DRIFT OF THE “NORTH POLE-1” RESEARCH STATION

Every year on May 21 in our country is celebrated Polar Day. And not without purpose, because that day in 1937 the world-famous event took place: the four-engine N-170 airplane, piloted by M.V. Vodopyanov, landed on the ice of the Arctic Ocean in the region of the North Pole (89º25’N and 78º40 ‘w.d.). Here began the path of the scientific drifting station North Pole-1. This was the first scientific expedition in the North Pole area, in 274 days it drifted 2,100 km to the southern tip of Greenland (Cape Forvel). More than a hundred books and articles have been written about the history of its creation, the legendary drift, participants and scientific results. First of all, the diaries of the participants should be included here. Reading these books and having an idea of the north by participating in sea expeditions to the Arctic, one involuntarily wonders how people survived and worked in such difficult conditions, about the nature surrounding them and how variable the weather could be above their heads. Comparing the selection of photographs with the diaries of the drift participants, we tried to trace how the situation (landscapes of the drift) changed from the moment of landing and until the removal of the Papanin camp on February 19, 1938. The article is dedicated to the 125th anniversary of the head of the expedition SP-1 – I.D. Papanin. Photo materials for the article are based on the I.D. Papanin handed over to his father K.V. Popov – to Vladimir Ivanovich Popov, who worked under the direction of I.D. Papanin at the Research Institute of Inland Waters of the USSR Academy of Sciences in the village of Borok, and his former friend.

A comprehensive in situ and remote sensing data set from the Arctic CLoud Observations Using airborne measurements during polar Day (ACLOUD) campaign

The Arctic CLoud Observations Using airborne measurements during polar Day (ACLOUD) campaign was carried out north-west of Svalbard (Norway) between 23 May and 6 June 2017. The objective of ACLOUD was to study Arctic boundary layer and mid-level clouds and their role in Arctic amplification. Two research aircraft (Polar 5 and 6) jointly performed 22 research flights over the transition zone between open ocean and closed sea ice. Both aircraft were equipped with identical instrumentation for measurements of basic meteorological parameters, as well as for turbulent and radiative energy fluxes. In addition, on Polar 5 active and passive remote sensing instruments were installed, while Polar 6 operated in situ instruments to characterize cloud and aerosol particles as well as trace gases. A detailed overview of the specifications, data processing, and data quality is provided here. It is shown that the scientific analysis of the ACLOUD data benefits from the coordinated operation of both aircraft. By combining the cloud remote sensing techniques operated on Polar 5, the synergy of multi-instrument cloud retrieval is illustrated. The remote sensing methods were validated using truly collocated in situ and remote sensing observations. The data of identical instruments operated on both aircraft were merged to extend the spatial coverage of mean atmospheric quantities and turbulent and radiative flux measurement. Therefore, the data set of the ACLOUD campaign provides comprehensive in situ and remote sensing observations characterizing the cloudy Arctic atmosphere. All processed, calibrated, and validated data are published in the World Data Center PANGAEA as instrument-separated data subsets (Ehrlich et al., 2019b, https://doi.org/10.1594/PANGAEA.902603).