Polar Science最新文献

Black carbon (BC) aerosol, released into the atmosphere from fuel combustion and biomass burning, is known to be an important short-lived climate forcer (SLCF) because it efficiently absorbs solar radiation and directly heats the atmosphere. Because its accumulation on snow and ice promotes their melting, BC is an important driver of warming, particularly in the Arctic region. Observed surface BC concentrations in the Arctic region show typical seasonal variations, increasing during the winter and spring and decreasing during the warmer season with some peak events in few months of summer, along with large interannual variations. The present study investigates the primary factors influencing the differences in the spatiotemporal surface concentrations of BC in the Arctic region by performing a hemispheric-scale air-quality simulation for the years 2015 and 2016. The model reasonably simulates the observed BC concentration levels and their seasonal patterns, as well as their differences between these two years. This study shows that large year-to-year variability in BC-rich air-mass pathways, such as long-range transport from surrounding regions, and besides these air-mass stagnation within the Arctic region, influence the differences in the Arctic BC concentrations between 2015 and 2016. In addition, the Arctic BC concentrations were also controlled by interannual variations in the amount and distribution of emissions due to the size and the location of open fires, including both Asian crop residue burning in spring and boreal forest fires in summer.

We reassess the research on the impact of climate change on society and propose examining the social dimensions of climate change from a perspective of community well-being. We argue that to better understand community dynamics in the Arctic, it is helpful to shift the research focus from the environment and view the environment and climate change as a backdrop to social phenomena. Specifically, we consider the increasing living standards and expanding basic needs that fall under consumption, one of the three domains of economic activity. This represents a shift from the conventional anthropological perspective, which focuses solely on production (food procurement, subsistence) and distribution, to a more balanced consideration of the three economic domains and their intricate relations. This shift also involves moving away from the conventional anthropological theory, which posits that the relationship to the environment influences, organizes, and shapes people's lives, to the reverse: people's increasing needs reshape, rearrange, or alter the human–environment relationship. The perspective of community well-being considers the interplay between the environment, social (local assets), and economic domains (consumption and increasing needs) of community dynamics. To illustrate this perspective in Arctic studies, we draw on two examples from our experience in Greenland: sheep farming in South Greenland and Greenland halibut fisheries in North Greenland.

This study focuses on assessing the concentrations, fluxes, and production rates of greenhouse gases (CO₂, CH₄, and N₂O) in a cold temperate grassland soil underlying snowpack during the winter of 1996/7 in northern Japan. Results included mean ± standard deviation (range) correlation coefficients (R²) for CO₂–CH₄ concentrations and CO₂–N₂O concentrations of 0.93 ± 0.07 (0.81–0.99) and 0.96 ± 0.06 (0.83–0.99) for winter, and 0.74 ± 0.17 (0.55–0.92) and 0.96 ± 0.05 (0.88–0.99) for summer, respectively. This suggests close relationships between the mechanisms of CO₂ and N₂O production and the oxidation of CH₄, which are influenced by factors such as oxygen availability, temperature, and moisture in the soil. Furthermore, the study found that winter fluxes of CO₂–CH₄ and CO₂–N₂O through the snowpack showed positive linear correlations. Winter CO₂ emissions accounted for 96 % of the variability in CH₄ oxidation and 77 % of the variability in N₂O emissions. This demonstrates that winter CO₂ emissions were affected to the magnitude of CH₄ oxidations and N₂O emissions in the soil. These findings have implications for the modification of terrestrial ecosystem models in temperate regions, particularly in assessing contributions from winter greenhouse gas fluxes to overall annual emissions. Understanding the interrelationships and dynamics of greenhouse gases throughout the year is crucial for accurate modeling and predictions of ecosystem responses to climate change.

Black carbon is an air pollutant that contributes to Arctic warming, and its control is the subject of multiple international institutions in the region. However, the potential for cost-effective reduction of black carbon emissions in the region is conditioned by the features of the national regulatory systems in relevant countries. This study conducted a comparative analysis of national pollution control systems for land-based sources of black carbon emissions in Arctic states and two key Arctic Council observer states, China and India. Doing so, the study shows that most countries have implemented at least some policies and regulatory measures in most pollution control areas. However, relevant policies are sometimes found outside the conventional domain of air pollution regulation, such as schemes for corporate reporting on sustainability. Substantial differences across countries lie in regulations' stringency and enforcement capacity. In addition, the national governance system, such as the federal systems of the US and Canada, influences the characteristics of black carbon policies and regulations. Furthermore, the application of economic instruments is limited in terms of the country coverage and economic instrument types. These features have implications for the design of domestic and international policies for Arctic black carbon control.

The Arctic is undergoing rapid environmental change that is creating a variety of environmental, social, political, and economic challenges for the people living in this region. These changes are not limited to the Arctic, but are global, affecting weather, ecosystems, and human society at low, mid, and high latitudes. Many unresolved issues remain concerning the warming phenomenon in the Arctic, its causes, and its effects on mid-latitude regions, and these issues were addressed at the 7th International Symposium on Arctic Research (ISAR-7) held in Tokyo, Japan, from March 6–10, 2023. The symposium was broadly interdisciplinary, with particular emphasis on research in the social sciences and humanities. This special issue of ISAR-7 brings together papers that span a variety of disciplines and their linkages to promote the information and knowledge needed for the future sustainable development of the Arctic.

Although Antarctic soils are usually described as weakly developed, recent studies indicated the significant variability in soil forming conditions across the sixth continent as well as considerable diversity of soils. The identification of pedogenetic processes in Antarctica is crucial for understanding not only the current state of its environment, but also for better understanding of soil development on Earth through time. Our study provides a detailed investigation of micromorphological features and molecular composition of organic matter of soil and soil-like bodies of remote areas of East Antarctica - Larsemann Hills and Bunger Hills, which are characterized by harsh environmental conditions. Studied soils showed predominantly coarse structure and low organic carbon content, alkaline to almost neutral pH range. Thin sections of studied soils were characterized by predominance of grains of quartz, feldspars, and other primary minerals with angular shapes indicating relatively weak degree of their alteration. All studied humic substances are characterized by the predominance of aliphatic structures. Moreover, it was observed that studied humic acids contains significant amounts of carbohydrates, polysaccharides, esters and amino acids and hydrophilic fragments predominate. Organo-mineral interactions were mostly connected with development of biofilms in the topsoil horizons with the maximal biological activity among studied soils.

The Larsemann Hills and surrounding regions have been widely explored and studied from the year-round stations Progress (Russia), Zhongshan (China) and Bharati (India), and the seasonal-facility Law Base (Australia). The proximity of stations fosters scientific engagements and cooperation on the Antarctic continent. The first International Conference on Antarctic Research (ICAR) at Bharati in 2020 is one such example. The special issue (Parts 1 and 2) on Larsemann Hills is an outcome of the ICAR-2020. In addition, the BRICS working group on ocean and polar science and technology (OPST) provided an effective platform for strengthening scientific cooperation. Part 2 of the special issue compiles thirteen papers from diverse disciplines of Antarctic science.

We report, in this work, the changes in the thermal structure of the mesosphere-lower thermosphere (MLT) region over an Indian Antarctic station Bharati (69.4° S, 76.2° E, CGM coordinates 75° S, 97° E) brought about by an intense geomagnetic storm of 23–24 March 2023 (Dst ∼ −155 nT). We use the temperature and OH airglow measurements of the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard NASA's Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission satellite to compare the thermal field of the MLT region on these disturbed days with the neighbouring quietest days of 27–28 March. Such comparison reveals both warming and cooling in the MLT region associated with the storm. An extension of this comparative study in the latitude region located poleward of Bharati also shows similar behavior of the MLT region during this geomagnetic storm. Overall, this study reveals the maximum temperature enhancement of ∼39–43 K to occur at around 99 km, a significant warming of ∼4–43 K in 95–105 km, and a decrease of ∼12–16 K in 80–87 km. While the enhancement of temperature in 95–105 km appears to be a consequence of the auroral heating associated with this storm; we are unable to account for the cooling below based on existing theories. Present observation of the development of cooling underneath the region of temperature enhancement during the geomagnetic storm is rare and demands further investigation.

The National Remote Sensing Centre (NRSC) has established its ground station named Antarctica Ground Station for Earth Observation Satellites (AGEOS) at Bharati station located at Larsemann hills area of Antarctica for the tracking and data acquisition from polar orbiting satellites. A communication link through a geostationary satellite in C-band is being used for transferring data to the mainland. There is a need to enhance the data rate in the near future considering the huge volume of data being acquired at AGEOS. A satellite link operating at Ka-band is proposed for accommodating the bandwidth requirements. It is necessary to estimate the worst case atmospheric attenuation at Ka-band over Larsemann hills area for calculating the link margins required. The India Meteorological Department (IMD) has setup a wide range of meteorological instruments at Bharati station and the local data collected for the years 2020, 2021 and 2022 are used in this study. The link is assumed to operate at a frequency of 20 GHz with linear polarization. An exceedance probability of 0.1% is used to arrive at the annual statistics of the attenuation. Recommendations by the International Telecommunication Union (ITU) are followed and the estimation is carried out using MATLAB. An estimated total atmospheric attenuation of 2.28 dB is obtained. The results are used further for carrying out link budgeting for a Ka-band satellite communication link between Bharati station and India.

Supraglacial discharge of limiting micronutrients such as iron (Fe) into high-nutrient low-chlorophyll (HNLC) regions like the Southern Ocean has recently drawn global attention. In this study, we aim to understand the contribution of cryoconite holes (comprising a meltwater column with an underlying layer of sediment) to the discharge of Fe through the glacier runoff. Cryoconite hole meltwater collected from the Larsemann Hills, East Antarctica showed a higher concentration of dissolved Fe (dFe: 71.2 μgL⁻¹) and total Fe extractable from suspended sediments (exFe: 362.1 μgL⁻¹) than in the adjacent streams (dFe: 30.5 μgL⁻¹; exFe: 21.2 μgL⁻¹) and melt pools (dFe: 42.3 μgL⁻¹; exFe: 5.8 μgL⁻¹). Predictive pathways (using PICRUSt2) show that cryoconite hole bacterial communities could acquire Fe and other trace elements using different mechanisms, such as the biosynthesis of siderophores, and transport proteins, therefore influencing the trace metal chemistry in these and other environments that drain cryoconite hole contents. Estimated discharge of dFe (11.4 kg km⁻² a⁻¹) and exFe (57.9 kg km⁻² a⁻¹) within cryoconite holes are 2 and 17 times higher, respectively than the discharge from the adjacent supraglacial streams, indicating that cryoconite holes are an important source of potentially bioavailable Fe to the HNLC region.