Are cyclones in Jupiter's polar regions modulated by the radially directional Rayleigh–Taylor instability?

The persistence and symmetry of cyclones around the poles of Jupiter are unknown.In the present investigation,inspired by cyclones at the South Pole of the Earth,we propose a mechanism that provides an explanation for this problem.The negative temperature gradient with respect to latitude may play an important role here.This temperature gradient is induced by solar radiation because of the small axial inclination of Jupiter.Our numerical simulations suggest that cyclones in the polar regions of Jupiter may be modulated or controlled by the radially directional Rayleigh–Taylor instability,driven by centrifugal force and the negative temperature gradient along the latitude.

Evaluation of the Polar Code in different environments and for different maritime activities in the two polar regions

Because of the decrease in sea ice coverage,maritime activities in the polar regions have increased steadily over the years and several issues related to maritime activities have arisen.It is essential to understand these challenges because they could have serious political,environmental,and economic consequences.Although there are significant geographical and legal differences and differences in the types of activities between the Arctic and the Antarctic,a single International Maritime Organization Polar Code covers both regions.In this analysis,changes in polar regions are introduced,and the differences between the Arctic and Antarctic are discussed.The differences in maritime activities in the two polar regions are then discussed,and the Polar Code is evaluated in terms of these differences.

Soliciting Contributions to a Special Issue of "Current Research on Atmospheric Aerosols and Trace Gases over the Polar Regions" in Advances in Polar Science

Dear Colleagues, We would like to invite you to submit manuscripts to a special issue entitled ＂Current Research on Atmospheric Aerosols and Trace Gases over the Polar Regions＂ of the Journal Advances in Polar Science （APS）. APS is an international, peer-reviewed journal jointly sponsored by the Polar Research Institute of China （PRIC） and the Chinese Arctic and Antarctic Administration （CAA）. It is a quarterly journal published in March, June, September and December by Science Press of China and circulated internationally （ISSN 1674-9928, CN 31-2050/P）. Articles published in APS are free of charge with generous funding from PRIC. For more details, please visit the APS＇s websites. Thank you in advance for your consideration to submit manuscripts to this special issue, and we encourage you to share this announcement broadly with interested colleagues.

A mesoscale model used in the Polar regions:modification and verification

A polar version of mesoseale model, Polar MM5 is introduced in the paper. The modifications for the polar MM5 dynamics and physics compared with standard MM5 are described. Additionally, parallel simulations of the Polar MM5 and original MM5 reveal that the Polar MM5 reproduces better near-surface variables forecasts than the original MM5 over the North American Arctic regions. The well predicted near surface temperature and mixing ratio by the Polar MM5 confirm the modified physical parameterization schemes in the Polar MM5 are appropriate for the research region.

Progress in application of MODIS for remote sensing in Polar Regions

The remote sensing technique is widely used in Polar Regions,and Moderate Resolution Imaging Spectroradiomete（MODIS） is one of the most important satellite sensors in the domain of remote sensing.In this article,MODIS sensor,including the information of its satellites,its system constitutes,its hardware characteristic,its large spectra and usual applications are briefly introduced first.Then,there is a particular introduction of MODIS＇s use in Polar Regions,which refers to the polar physiognomy,polar atmosphere and polar ocean,with citing many examples.At last,views about the development of MODIS and its series sensors in the future,including the improved applications in Polar Regions are given.

The research of Polar sea ice and its role in climate change

As an important part of global climate system, the Polar sea ice is effccting on global climate changes through ocean surface radiation balance, mass balance, energy balance as well as the circulating of sea water temperature and salinity. Sea ice research has a centuries - old history. The many correlative sea ice projects were established through the extensive international cooperation during the period from the primary research of intensity and the boaring capacity of sea ice to the development of sea/ice/air coupled model. Based on these reseamhes, the sea ice variety was combined with the global climate change. All research about sea ice includes： the physical properties and processes of sea ice and its snow cover, the ecosystem of sea ice regions, sea ice and upper snow albedo, mass balance of sea ice regions, sea ice and climate coupled model. The simulation suggests that the both of the area and volume of polar sea ice would be reduced in next century. With the developing of the sea ice research, more scientific issues are mentioned. Such as the interaction between sea ice and the other factors of global climate system, the seasonal and regional distribution of polar sea ice thickness, polar sea ice boundary and area variety trends, the growth and melt as well as their influencing factors, the role of the polynya and the sea/air interactions. We should give the best solutions to all of the issues in future sea ice studying.

Cryoseismologic Studies for Polar Environment—Recent Progress of Japanese Contribution

Majority areas of Antarctica and Greenland are under the thick ice sheet and characterized by evolving cryosphere surroundings. In the polar region, associated with the recent trend on climate change such as global warming, glacier relating earthquakes are increasing during this 21st century. In this paper, a decade of progress in “Cryoseismology” at bi-polar regions is re-viewed by focusing on the contribution from Japanese researchers. In particular, the specific cryoseismic events are treated, which occurred in the coastal area of East Antarctica, around the Lützow-Holm Bay, together with the coast and whole inland area of Greenland. As the major scientific results, frequency-overtone signals in the harmonic cryoseismic tremors were analyzed by assuming constant sources, suggesting inter-glacial asperities that generate characteristic tremors. Infrasound source locations were also determined by using the array deployment at the coastal regions in the Antarctic. In contrast, characteristics of glacial earthquakes and seismic interferometry approach have been conducted so as to achieve the fine structure of the Greenland Ice Sheet (GrIS) in particular the basal condition beneath the ice sheet.

Progress in polar upper atmospheric physics research in China

The Chinese Antarctic Great Wall, Zhongshan, Kunlun and Arctic Yellow River stations have unique geographical locations, well suited to carry out polar upper atmospheric observations. This paper reviews the tremendous history of nearly 30 years of Chinese polar expeditions and major progress in polar upper atmospheric physics research. This includes the polar upper atmospheric physics conjugate observation system at Zhongshan Station in the Antarctic and Yellow River Station in the Arctic, and original research achievements in polar ionospheric fields, aurora and particle precipitation, the polar current system, polar plasma convection, geomagnetic pulsations and space plasma waves, inter-hemispheric comparisons of the space environment, space weather in polar regions, power spectrum of the incoherent scatter radar, ionospheric heating experiments and polar meso- spheric summer echoes, polar ionosphere-magnetosphere numerical simulation and others. Finally, prospects for Chinese polar upper atmospheric physics research are outlined.

Distribution of charged lunar dust in the south polar region of the moon

Lunar dust is one of the most threatening problems confronting the return of human beings to the moon.In this work we studied the spatial distribution behavior of charged lunar dust in the solar wind plasma environment in the south polar region of the moon and considered the influence of a mini-crater using Spacecraft Plasma Interactions Software.The distribution of dust and plasma at low solar altitude angles of 20°and 0°was studied,and the spatial density of lunar dust was~10^(10.4)m^(-3)and~10^(11.5)m^(-3),respectively.This is because a higher surface potential will result in transportation of small dust particles and photoelectrons can also neutralize positively charged lunar dust.The dust density in the plasma void region created by a mini-crater with a 5 m high wall was studied.We obtained a quasi-neutral electric environment in the plasma void region of the mini-crater,and the dust density was about a magnitude lower than that in other regions.The dust risk to a spacesuit is much lower on the nightside than on the dayside,but there is severe charged lunar dust transport in the region between light and shade,which is dominated by the difference in surface and plasma potential caused by photoelectrons.

Simulated perturbation in the sea-to-air flux of dimethylsulfi de and the impact on polar climate

Marine biogenic emission of dimethylsulfi de(DMS)has been well recognized as the main natural source of reduced sulfur to the remote marine atmosphere and has the potential to aff ect climate,especially in the polar regions.We used a global climate model(GCM)to investigate the impact on atmospheric chemistry from a change to the contemporary DMS fl ux to that which has been projected for the late 21 st century.The perturbed simulation corresponded to conditions that pertained to a tripling of equivalent CO 2,which was estimated to occur by year 2090 based on current worst-case greenhouse gas emission scenarios.The changes in zonal mean DMS fl ux were applied to 50°S–70°S Antarctic(ANT)and 65°N–80°N Arctic(ARC)regions.The results indicate that there are clearly diff erent impacts after perturbation in the southern and northern polar regions.Most quantities related to the sulfur cycle show a higher increase in ANT.However,most sulfur compounds have higher peaks in ARC.The perturbation in DMS fl ux leads to an increase of atmospheric DMS of about 45%in ANT and 33.6%in ARC.The sulfur dioxide(SO 2)vertical integral increases around 43%in ANT and 7.5%in ARC.Sulfate(SO 4)vertical integral increases by 17%in ANT and increases around 6%in ARC.Sulfur emissions increases by 21%in ANT and increases by 9.7%in ARC.However,oxidation of DMS by OH increases by 38.2%in ARC and by 15.17%in ANT.Aerosol optical depth(AOD)increases by 4%in the ARC and by 17.5%in the ANT,and increases by 22.8%in austral summer.The importance of the perturbation of the biogenic source to future aerosol burden in polar regions leads to a cooling in surface temperature of 1 K in the ANT and 0.8 K in the ARC.Generally,polar regions in the Antarctic Ocean will have a higher off setting eff ect on warming after DMS fl ux perturbation.

A comparative study on the ionospheric current systems in the Antarctic and Arctic regions

The current systems representing the solar and lunar daily variations (S and L) of the gcomagnetic field have been calculated on the basis of the date obtained from the global network Of gcornagnetic observatories. The characteristics of these current.systems in the Antarctic and Arctic regions have been analysed comparatively. The results show that: (1) There are certain differences in the current systems of these two regions, that implies definite differences in the ionospheric dynamo process, responsible for both S and L, and the field-aligned current, responsible for S. The differences of the magnetic field structure in these two polar regions may be the basic reason of the above-mentioned differences. (2) There are remarkable differences in the internal current systems of these two polar regions, that is attributed to both the inducing field (current) and the underground conductivity. In general, the conductivity of the Antarctic region is higher than that of the Arctic region.

An outstanding example of cooperation between Arctic and non-Arctic countries in cryosphere and climate research: Sino-Finnish cooperation for more than 30 years

The cryosphere is interconnected with other components of the climate system through global exchange of water,energy,and carbon.Long-term sustainable and pragmatic scientific and technological cooperation on the cryosphere and climatology in polar and sub-polar regions between China and Finland began in the 1980s.The fields of bilateral cooperation include joint training of young scientists,joint field observations,climatological and ecological researches of polar and sub-polar sea ice,glaciers and frozen lakes,etc.The year 2020 marked the 70th anniversary of the establishment of diplomatic relations between China and Finland.In order to celebrate the great achievements by Chinese and Finnish scientists in the fieldsof cryosphere and climate research,the Advances in Polar Science invited scientists from both sides to jointly organize a Special Issue entitled“Sino-Finnish cooperation on cryosphere and climatology in polar and sub-polar regions”.In this Special Issue,we have collected 10 papers,with most papers created jointly by scientists of both sides.The fruitful scientific achievement is strongly benefited from the sustainability of cooperation.Monitoring,research,prediction,mitigation,and adaptation to the climate change in the polar and sub-polar regions will definitively stay in the focus for many decades to come.A new era of Finnish-Chinese scientific collaboration on cryosphere has begun.

The Nippon/Norway Svalbard Meteor Radar: First results of small-scale structure observations

The Nippon/Norway Svalbard Meteor Radar(NSMR), has been in operation since March 2001. While primarily thought of as an instrument for examining mean wind, tidal and gravity wave neutral atmosphere dynamics in the upper mesosphere region, it is also possible to investigate spatial and temporal structure of temperature and windshear. Here, the radar itself is described followed by a presentation of these derived parameters.

OBSERVATIONAL STUDY OF MERIDIONAL VARIATION OF UV-B RADIATION DURING VOYAGES TO THE ARCTIC AND ANTARCTIC REGIONS

Based on 1999-2000 observations made by the first Arctic and sixteenth Antactic scientific voyages,a study is undertaken about the meridional surface UV-B (B band ultraviolet rays) variations in 75°N-70°S.It is mitigated as a function of latitudes and marked by lower radiation averaged over the Northern Hemisphere (NH) than over the Southern Hemisphere (SH),with its daily course basically similar to that of total radiation.Around polar summer noon hours (local time) and where ice albedo is maximum,the strongest UV-B irradiance on the surface perpendicular to sun's beams as found at equatorial latitudes is measured sometimes.In the areas near Zhongshan Station the increase of surface UV-B radiation shows a close relation to the decrease of ozone in the higher atmosphere but it has a less intimate relation with its concentration at ground.

High-efficiency all-dielectric transmission metasurface for linearly polarized light in the visible region

We propose and numerically investigate an efficient transmission-mode metasurface that consists of quasicontinuous trapezoid-shaped crystalline silicon nanoantennas on a quartz substrate. This metasurface provides a linear phase gradient and realizes both full 2π phase shift and high transmission efficiency in the operating wavelength range from 740 to 780 nm. At the central wavelength around 751 nm, the total transmission efficiency is up to 88.0% and the section of the desired anomalous refraction is 80.4%. The anomalous refraction angle is 29.62°, and larger refraction angle can be achieved by changing the period of the super cell. We demonstrate a refraction angle as large as 38.59°, and the anomalous transmission efficiency reaches 76.6% at wavelength of 741 nm. It is worth mentioning that the structure is much simpler than conventional metasurfaces based on arrays of discrete nanoantennas. Our research may pave the way for designing efficient all-dielectric phase-gradient metasurfaces and applying them in integrated optical devices for wavefront control.

NONLINEAR ELECTROSTRICTIVE PROPERTIES OF PbZrO_(3):Sn SINGLE CRYSTALS WITH ANTIFERROELECTRIC PHASE TRANSITIONS

The electrostrictive properties above Te max represented by the field-related and polarization-related M and Q coefficients have been measured for PbZr_(1-x)Sn_(x)O_(3)single crystals with ani-ferroelectric phase transitions.The investigations presented in this paper have proved that the M_(11)(T)and Q_(11)(T)runs bring direct information of the pre-transitional effects connected with the co-existence of local polar objects with nonpolar matrix.Due to this co-existence,nonlinear Q_(11)(T)dependence in the neighborhood of T_(C)has been detected.Observed even in a wide tem-perature above T_(C),this co-existence is a natural feature of the material with ABO_(3)perovskite structure that undergoes structural transition to po lar phase.