Northern Polar Region Research Articles

Quasi-10-day waves in temperature and polar mesospheric clouds: Results of AIM/SOFIE and Aura/MLS observations

Planetary waves, including quasi-2, -5, -10, −16-day waves, play significant roles in stratospheric dynamics. However, the existing knowledge on quasi-10-day waves (Q10DWs) at high latitudes is limited. This paper investigated the interannual and seasonal variations of Q10DWs with zonal wave numbers varying from the −3 (westward propagation) to 3 (eastward propagation) modes from 2008 to 2022, using temperature data measured by the Microwave Limb Sounder instrument (316−0.001 hPa, corresponding to an altitude of approximately 8–97 km) and temperature/ice water content data measured by the Solar Occultation for Ice Experiment (SOFIE) instrument (10−100 km at latitudes >55°). The findings revealed that the amplitude of Q10DWs in winter was higher than that in other seasons. The amplitude of Q10DWs was observed to substantially decrease with an increase in wavenumber. In addition, the amplitude of stationary Q10DWs in the northern polar region exceeded that in the southern polar region. Moreover, we used observational data from the SOFIE instrument, which simultaneously measures temperature and ice water content (IWC) in the mesosphere, to examine the variations of Q10DWs with respect to the temperature and IWC. Our findings suggest that in the northern polar region, the maximum value of Q10DWs in IWC was occasionally observed earlier than the lowest value of Q10DWs in temperatures.

Water Transport in the Mars Northern Winter Polar Atmosphere: Observations and Simulations

AbstractThis study involving both observations and simulations furthers our understanding of water transport in the Martian northern polar region, a critical component of the global water cycle, and explores strengths and weaknesses in simulations of the polar atmosphere. Observations of the northern polar winter by the Mars Climate Sounder (MCS) onboard the Mars Reconnaissance Orbiter show extensive water ice clouds over the polar ice cap throughout the 300–3 Pa (∼10–50 km) vertical column within the vortex during the entire winter season. The observations also indicate that the vortex evolves throughout its depth on a broad range of timescales, from sub‐diurnal to seasonal. Time sequences of these data together with results from a Mars global circulation model and Ensemble Mars Atmosphere Reanalysis System reanalysis (EMARS) are used to study the evolution of the winter polar atmosphere and to examine dynamic mechanisms for transporting water across the vortex boundary. Model simulations and reanalysis show a similar temperature structure to observations, although they struggle to reproduce some of the detailed features such as the extent of polar warming above the vortex and the magnitude of the temperature minima inside the vortex. The free run simulation also fails to capture the vertically distributed water ice cloud due to a general absence of transport across the vortex boundary. EMARS results, with assimilated MCS temperatures, show a greater amount of water entering the vortex at pressures below 200 Pa, leading to a more vertically extended cloud within the vortex and improving agreement with observations.

Measurements of particulate methanesulfonic acid above the remote Arctic Ocean using a high resolution aerosol mass spectrometer

Methanesulfonic acid (MSA) is an important product from the oxidation of dimethyl sulfide (DMS), and thus is often used as a tracer for marine biogenic sources and secondary organic aerosol. MSA also contributes to aerosol mass and potentially to the formation of cloud condensation nuclei and new particles. However, measurements of MSA at high temporal resolution in the remote Arctic are scarce, which limits our understanding of its formation, climate change impact and regional transport. Here, we applied a validated quantification method to determine the mass concentration of MSA and non-sea salt sulfate (nss-SO4) in PM2.5 in the marine boundary layer, using a high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) during a research cruise to the Arctic and North Atlantic Ocean, between 55 °N and 68 °N (26th May to June 23, 2022). With this method, the concentrations of MSA in the remote Arctic marine boundary layer were determined for the first time. Results show that the average MSA concentration was 0.025 ± 0.03 μg m−3, ranging from <0.01 to 0.32 μg m−3. The lowest MSA level was found towards the northern leg of the cruise (near Sisimut (67 °N)) with air masses from sea ice over the northern polar region, and the highest MSA concentrations were observed over the Atlantic open ocean. The diurnal cycles of gas MSA, particulate MSA and nss-SO4 peaked in the afternoon, about one hour later than that of peak of solar radiation, which suggests that photochemical process is an important mechanism for the conversion of DMS into MSA above the remote ocean. The mass ratio of MSA to nss-SO4 (MSA/nss-SO4) presents a temperature dependence, which indicates that the addition branching pathway favors MSA formation, while thermal decay of intermediate radicals could be a possible pathway for sulfate formation. Finally, we found that the MSA/nss-SO4 ratio is around 0.22-0.25 in the remote northern marine atmosphere.

On the reachability and genesis of water ice on the Moon

Understanding the reachability of water ice by future in-situ experiments near the lunar poles is crucial for supporting growing exploration plans and constraining the uncertainties on its genesis and distribution. To achieve this objective, we perform a thorough three-dimensional mapping of the distribution of water ice in the lunar polar regions (70° onward), integrating radar, optical, and neutron detector observations from the Lunar Reconnaissance Orbiter mission (LRO). Our analysis reveals ∼5-to-8-fold larger expanse of subsurface water ice (∼1-3 m depth) compared to surface water ice (up to 1 m depth) for the north and south poles, respectively. Our investigation cannot rule out the possibility of deep-seated water ice deposits in the lunar poles that remains beyond the detection capabilities of existing instruments on LRO. Moreover, we find that the extent of water ice in the northern polar region (∼1100 ± 74 km2) is twice that in the southern polar region (∼562 ± 54 km2). Our mapping also suggests that the dichotomous latitudinal distribution and the antipodal longitudinal distribution of water ice are likely driven by Mare volcanism and preferential cratering. We provide additional evidence that outgassing during Imbrian volcanism was probably the primary source of subsurface water ice in the lunar poles, which favors larger expanse over meteoritic sources.

Simulated dust activity in typical time periods of the past 250 million years

The dust cycle in three typical time periods of the past 250 Myr, namely 240 Ma, 130 Ma and 80 Ma, is studied using the climate model CESM1.2.2 combined with the vegetation model BIOME4 and compared with that of the present day. The atmospheric dust loading obtained for these three periods is 35.9, 9.7 and 3.2 Tg, respectively. In comparison, the present-day dust loading is ∼24 Tg. It is found that the area of subtropical land is the major controlling factor in the variation of dust loading; the climate and the land plant evolution play a relatively minor role in these experiments where continental ice sheets are not considered and the reliability of BIOME4 in simulating vegetation of deep time is still uncertain. Although the simulated atmospheric dust loading in 240 Ma was much higher than that simulated for today, the fraction of dust deposited into the ocean (26%) was much lower due to its supercontinental configuration. Dust was able to cool the local annual mean surface temperature by a maximum of 2 °C in 240 Ma. A warming is obtained in the northern polar region in both 240 Ma and 130 Ma, likely due to strengthened meridional oceanic heat transport rather than due to snow darkening.

Numerical experiments on paleoclimate modeling

The influence of climatic parameters (values of CO2 concentration in the atmosphere, solar constant), the configuration of continents, as well as the distribution of the depths of the World Ocean, characteristic of the time periods under consideration, on the climate is investigated. A global climate model is used, including a model of three-dimensional thermohaline circulation of the ocean, an energy-moisture balance model of the atmosphere and a model of the sea ice evolution. Numerical experiments have been carried out to model the climate corresponding to the periods 120.4 million years ago and 200 million years ago with sharply different parameters. The first interval was characterized by high CO2 concentrations and a continent lying in meridional direction. During the second interval a super continent was located in the Northern polar region extending to the South but not reaching the South Pole. Calculations show that the average global climatic characteristics achieve to a stationary regime during about 1500-2000 years. The main global and spatial climatic characteristics for the atmosphere, ocean, and sea ice are obtained. The estimated average global atmospheric temperature falls within the limits reconstructed from observations. The features of ocean circulation for the corresponding periods are studied.

Implication of kilometre-scale fluctuations on the MGS radio-occultation-derived electron density profiles: artefacts or ionospheric wave-like structures

ABSTRACT This study investigates the vertical kilometre-scale fluctuations (KSFs) seen on the Mars Global Surveyor (MGS) radio-occultation (RO)-derived electron density profiles (EDPs) by wavelet spectrum analysis. A delicate five-peak signature is revealed: in the northern polar region near the dawn–dusk terminator, the amplitudes of the KSF peak at fixed altitudes with a constant separation of approximately 28 km. The feature could not be noticed on a single EDP; averaging with at least tens of continuously collected EDPs is needed, suggesting that the phenomenon is not instantaneous (time duration of each RO event is ∼7 min), but on a time-scale of days (observation time for tens of continuous RO events). Applying similar background criteria, Mars Atmosphere and Volatile EvolutioN (MAVEN) Radio Occultation Science Experiment derived EDPs could also occasionally capture similar multipeak features, indicating either that it is a natural ionospheric structure or that both MGS and MAVEN suffer the same artefact. The two indications are discussed, and a preliminary hypothesis is raised. A linear superposition with a 28 km standing wave might modulate the amplitude of KSF, and the 28 km standing wave might be associated with the ionospheric buoyancy waves disturbed by the upstream solar wind, while the plasma instabilities might trigger the KSF in the backgrounds of the draped magnetic field and day-to-night neutral winds.

International Law Basics of Governance of Subsoil in Kara Sea

Introduction. International law issues of using subsoil are addressed in many legal researches, which cover the normative content of this term and the subsoil extension of a state sovereignty within the state’s boundaries and also the status of marine subsoil both within and beyond the continental shelf. Taking into account this wide array of research materials this paper addresses a rather specific topic, which is of huge economic importance for Russia, that is the past, present and future legal mechanism of subsoil management in Kara Sea. In addition to that the paper address in this context the sharp change in 2022 the international legal policy in the Northern Polar region, which was initiated by the seven western countries-members of the Arctic Council.Materials and methods. International and national legal documents of the Russian Empire and the Soviet Union and also Russian Federation (which are applicable to the bottom of the Kara Sea) are used as materials for this research. The teachings of the qualified legal scholars devoted to these documents are also scrutinized. The author has relied upon general research methods as well as those which are specifically used by lawyers.Results of the research. During the period of the Russian Empire only suggestions were published as to the international law possibility to extend the administrative functions of Russia to the bottom of the whole Kara Sea. During the soviet period (until Gorbachev’s “perestroika” start in 1985) Kara Sea bottom and its subsoil were unanimously qualified as a part of state’s maritime territory of the Soviet Union. The relevant act of legislation, however, was never adopted. At the same time, no legal act was adopted, what might contradict the doctrinal qualification of Kara Sea and its subsoil as being under the sovereignty of the USSR and under its exclusive state control. In 1985 such a legal approach ceased to exist: according to the first northern “Gorbachev’s” Decree of the Council of Ministers of the USSR only small part of the subsoil of Kara Sea was legally qualified as being under the sovereignty of the country. As for the larger part of such subsoil, it has legally received a “weaker” status – as subsoil of the continental shelf implying that foreign states have some rights on the continental shelf.Discussion and conclusions. Up till nowadays the legal response of Russia to western states “sanctions” after the Coup d’Etat in Kiev in 2014 were always within international economic law. The fact that western countries introduced in 2022 nonregional disagreements with Russia in the policy in the Arctic Region has legal consequences for Russia. From this moment Russia is also free from the former tradition to respect its previous self-limitations in the Arctic relating to such western states. That covers, inter alia, self-limitations provided in the 1985 Decree relating to the status of subsoil in Kara Sea. In such a context the paper suggests “asymmetric” measures to be adopted by the Russian Federation within the law of the sea.

The global impact of the transport sectors on the atmospheric aerosol and the resulting climate effects under the Shared Socioeconomic Pathways (SSPs)

Abstract. A global aerosol–climate model is applied to quantify the impact of the transport sectors (land transport, shipping, and aviation) on aerosol and climate. Global simulations are performed for the present day (2015), based on the emission inventory of the Climate Model Intercomparison Project Phase 6 (CMIP6), and for near-term (2030) and mid-term (2050) future projections, under the Shared Socioeconomic Pathways (SSPs). The results for the present day show that land transport emissions have a large impact on near-surface concentrations of black carbon and aerosol nitrate over the most populated areas of the globe, but with contrasting patterns in terms of relative contributions between developed and developing countries. In spite of the recently introduced regulations to limit the fuel sulfur content in the shipping sector, shipping emissions are still responsible for a considerable impact on aerosol sulfate near-surface concentrations, about 0.5 to 1 µg m−3 in the most travelled regions, with significant effects on continental air pollution and in the northern polar regions as well. Aviation impacts on aerosol mass are found to be quite small, of the order of a few nanograms per cubic metre, while this sector considerably affects particle number concentrations, contributing up to 20 %–30 % of the upper-tropospheric particle number concentration at the northern mid-latitudes. The transport-induced impacts on aerosol mass and number concentrations result in a present-day radiative forcing of −164, −145, and −64 mW m−2 for land transport, shipping, and aviation, respectively, with a dominating contribution by aerosol–cloud interactions. These forcings represent a marked offset to the CO2 warming from the transport sectors and are therefore very relevant for climate policy. The projections under the SSPs show that the impact of the transport sectors on aerosol and climate are generally consistent with the narratives underlying these scenarios: the lowest impacts of transport on both aerosol and climate are simulated under SSP1, especially for the land transport sector, while SSP3 is generally characterized by the largest effects. Notable exceptions to this picture, however, exist, as the emissions of other anthropogenic sectors also contribute to the overall aerosol concentrations and thus modulate the relevance of the transport sectors in the different scenarios, not always consistently with their underlying storyline. On a qualitative level, the results for the present day mostly confirm the findings of our previous assessment for the year 2000, which used a predecessor version of the same model and the CMIP5 emission data. Some important quantitative differences are found, which can mostly be ascribed to the improved representation of aerosol background concentrations in the present study.

Some patterns of formation of extreme surface air temperature in the area of the Spitzbergen (Svalbard) archipelago during the cold period

The article presents research findings of meteorological conditions during the formation of extreme surface air temperature (SAT) in the cold period from October to May in the Barentsburg area, the Spitzbergen (Svalbard) archipelago. Six extremely cold periods and six extremely warm periods for the weather sequence from 1912 to 2022 are considered. Correlation coefficients of extreme SAT in Barentsburg with extreme SAT in the points of Longyearbyen, Hornsund, Isfjord Radio, Pyramiden, Nu-Alesund, located in the west of Spitzbergen (Svalbard), were calculated. Also, characteristics of atmospheric circulation at the surface level, the level of the geopotential surface 500 hPa and 700 hPa and air temperature anomalies are analyzed, the results of comparing atmospheric circulation indices NAO and AO in the formation of extreme SAT are presented. Characteristic localizations of the polar vortex were found during the formation of negative and positive anomalies of SAT. For cold periods with extremely low temperatures, the localization of the polar vortex in the northeast of the Kara Sea and Severnaya Zemlya archipelago is observed. At the surface level the baric trough from the Atlantic depression is shifted to the coast of Scandinavia and the southern part of the Barents Sea. The Svalbard region is under the influence of the periphery of the anticyclonic field over the Arctic basin, Greenland, over the western Arctic Seas, conditions are formed for the deviation of SAT by 3–4 degrees below normal. In the case of extremely high SAT, the polar vortex is shifted to the eastern part of the Canadian Arctic Archipelago and the Baffin Sea. At the surface level, the baric trough from the Icelandic depression develops over the Greenland, Norwegian and Barents Seas, which leads to the moving of warm air masses from the Atlantic to polar latitudes and the formation of average SAT in the Spitzbergen (Svalbard) region above long-term values by 1–2 degrees. The estimates of macroprocesses obtained can be used for preparing long-term forecasts for the northern polar region and detailing them for the Spitzbergen (Svalbard) region.

Trends in the Socio-Economic Development of the Arctic Zone of the Russian Federation and the Importance of Cruise Tourism on the Northern Sea Route

The article discusses the prospects of socio-economic development of the territory of the Arctic zone of the Russian Federation and the role of the organization of Arctic tourism on the Northern Sea Route (NSR). Among all the northern countries of the world, Russia has the longest coastline in the Arctic seas and the largest sector of the adjacent shelf and waters of the seas of the Arctic Ocean (SLO). It is shown that, in comparison with neighboring Arctic countries, the potential of the development of tourist space and the development of Arctic tourism in the Russian Federation is far from being fully used. The current possibilities and prospects of using the nuclear icebreaker fl eet of the Russian Federation for the development of the Arctic zone of the Russian Federation (AZRF) are discussed. The prospects of improving the infrastructure of ports in the northern polar regions and the possibilities of developing Arctic cruise tourism on the NSR route are considered.

Study on the Hemispheric Asymmetry of Thermospheric Density Based on In-Situ Measurements from APOD Satellite

In this article, high spatiotemporal resolution data obtained by the atmospheric density detector carried by China’s APOD satellite are used to study the hemispheric asymmetry of thermospheric density. A detailed analysis is first performed on the dual magnetic storm event that occurred near the autumnal equinox on 8 September 2017. The results show that the enhancement ratio of atmospheric density in the southern polar region (SPR) on the duskside was approximately 1.33–1.65 times that of the northern polar region (NPR), demonstrating a strong hemispheric asymmetry of thermospheric atmospheric density response during the magnetic storm. However, the asymmetry response was smaller on the dawnside, suggesting that the hemispheric density response asymmetry is related to local time (LT). The energy injection in high-latitude regions increases local atmospheric density and forms traveling atmospheric disturbances (TADs). TADs can propagate to low-latitude regions over several hours and affect the global distribution of thermospheric atmospheric density. Similarly, the geomagnetic index fitting slope of SPR relative density difference is greater than that of NPR. The SuperDARN convection pattern indicates that the plasma convection velocity of SPR is significantly greater than that of NPR, indicating that joule heating caused by neutral friction of ions in the Southern Hemisphere may be stronger. Subsequently, an analysis of annual solar activity and seasons was carried out on the thermospheric NPR, SPR atmospheric density, and their differences from December 2015 to December 2020. The results show that thermospheric atmospheric density decreases overall as the number of sunspots decreases. The differences between the NPR and SPR atmospheric densities in the thermosphere exhibits a noticeable annual periodicity. The NPR and SPR atmospheric densities appear to have different distribution characteristics in different seasons. The NPR density peak is mainly in March or April. In particular, the “double-peak” phenomenon occurred in 2017, with peaks in March and September, while the most obvious feature of SPR atmospheric density is that its minimum value occurs in the summer months of June and July. This paper reveals the annual, seasonal, and magnetic storm response characteristics of the hemispheric asymmetry of thermospheric atmospheric density, which has significant implications for the study of multilayer energy coupling of the magnetosphere–ionosphere–thermosphere.

Trends and variability of total column ozone in the Third Pole

The Hindu Kush Himalaya and Tien Shan Mountain regions together are called the Third Pole (TP) of Earth, which encompasses ecologically fragile regions of 12 Asian countries. It is the highest mountain chain with the largest reserve of fresh ice mass on the planet outside the northern and southern polar regions. The TP region is experiencing high rate of glacier melting due to climate change for the past few decades, and is a great concern for water security of South Asia. Since changes in ozone concentrations in the atmosphere affect public health, ecosystem dynamics and climate, it is imperative to monitor its temporal evolution in an ecologically sensitive region such as TP. Here, the spatiotemporal characteristics of total column ozone (TCO) in TP and 20 selected cities in and around TP are investigated using a combined long-term data made from the satellite measurements of Ozone Monitoring Instrument (OMI) and Global Ozone Monitoring Experiment (GOME)-2B for the period 2005–2020. The spatial trends in TCO over TP are mostly negative in summer and autumn (from −0.2 DU/yr to −0.6 DU/yr), but positive in winter (up to +0.2 DU/yr). Among the selected 20 urban regions, the highest annual trend −0.42 ± 0.3 DU/yr and the lowest −0.01 ± 0.2 DU/yr are estimated in Xining and Chittagong, respectively. Analysis using a multiple regression model reveals that the ozone variability in TP is mostly driven by tropopause height with a contribution of 24.92%, Quasi-Biennial Oscillation (23.42%), aerosols (16.12%) and solar flux (15.34%). Our study suggests that the observed negative trend is mainly associated with human activities and climate change in TP, which would likely to enhance the surface temperature and thus, melting of glaciers in the region.

The Dynamics of Earth’s Cusp in Response to the Interplanetary Shock

The Earth’s magnetospheric cusp, a region with an off-equatorial magnetic field minimum, is an important place which directly transports plasma and energy from the solar wind into the magnetosphere and ionosphere. Its magnetic topology and charged particles therein are known to respond to the solar wind and the interplanetary magnetic field. However, its dynamics in response to the interplanetary (IP) shock are still unknown, due to lack of direct spacecraft observations. This study first reports the observations of the cusp’s motion under the drive of an IP shock and both strong electric fields and outflowing energetic ions in the moving cusp. After an IP shock arrival on 7 September 2017, triple cusps were observed by Cluster C4 when it was crossing the high-altitude northern polar region to the sub-solar magnetosphere. The multiple cusps had a one-to-one correspondence with the dayside magnetosphere compression and relaxation detected by THEMIS E, indicating that one cusp moved back and forth three times due to the IP shock’s impact. In the moving cusp, there were strong impulsive electric fields with a peak of up to ∼40 mV/m and an ionospheric source population of upward propagating ions (O+, He+ and H+) with energies extending to MeV. However, the outflowing ions outside the cusp had energies of no more than 1 keV. An enhancement of energetic O+ appeared inside the cusp with the flux ratio of O+/H+ increasing from 10 keV to ∼ MeV, which implies the efficient acceleration of O+. These observations are shown to be consistent with the prompt acceleration by the impulsive electric fields, which is mass-dependent. This finding suggests a new acceleration mechanism for cusp energetic ions, especially for O+.

Polar and Topographic Amplifications of Intermodel Spread of Surface Temperature in Climate Models

AbstractThe spatial pattern of intermodel spread of surface temperature (TS‐SPREAD) is similar to the absolute error of modeled surface temperature relative to observations, implying the possibility of using intermodel spread to understand the model biases. The regions with maximum TS‐SPREAD are located in the northern polar (NP) and southern polar (SP) regions, and regions with the large orographic features, such as the Tibetan Plateau (TP). We find: (a) Winter amplification exists in the TS‐SPREAD over both the NP and SP regions, but the maximum TS‐SPREAD over the TP happens during spring and summer with weak seasonality there. (b) Surface energy balance analyses show salient land‐sea contrast in the interlinkage between the physical processes. (c) Over the Arctic Ocean and the Southern Ocean, the maximum spreads of sea‐ice‐induced surface albedo appear during summer when the TS‐SPREADs are the weakest because the effect of surface albedo is offset by the heat storage in the oceans. (d) Through the interseasonal linkage of the heat storage term, i.e., the summer‐storing‐winter‐releasing of oceanic heat content, the summer surface albedo may indirectly contribute to the winter amplification of the TS‐SPREAD over the polar oceans. Such interseasonal linkage of the processes does not exist over the land areas. A method of distinguishing the roles of the local and nonlocal dynamical processes in the contribution of the clear‐sky downward longwave radiation to the TS‐SPREAD is also provided.

Antarctic permafrost degassing in Taylor Valley by extensive soil gas investigation

Ongoing studies conducted in northern polar regions reveal that permafrost stability plays a key role in the modern carbon cycle as it potentially stores considerable quantities of greenhouse gases. Rapid and recent warming of the Arctic permafrost is resulting in significant greenhouse gas emissions, both from physical and microbial processes. The potential impact of greenhouse gas release from the Antarctic region has not, to date, been investigated. In Antarctica, the McMurdo Dry Valleys comprise 10 % of the ice-free soil surface areas in Antarctica and like the northern polar regions are also warming albeit at a slower rate.The work presented herein examines a comprehensive sample suite of soil gas (e.g., CO2, CH4 and He) concentrations and CO2 flux measurements conducted in Taylor Valley during austral summer 2019/2020. Analytical results reveal the presence of significant concentrations of CO2, CH4 and He (up to 3.44 vol%, 18,447 ppmv and 6.49 ppmv, respectively) at the base of the active layer. When compared with the few previously obtained measurements, we observe increased CO2 flux rates (estimated CO2 emissions in the study area of 21.6 km2 ≈ 15 tons day−1). We suggest that the gas source is connected with the deep brines migrating from inland (potentially from beneath the Antarctic Ice Sheet) towards the coast beneath the permafrost layer. These data provide a baseline for future investigations aimed at monitoring the changing rate of greenhouse gas emissions from Antarctic permafrost, and the potential origin of gases, as the southern polar region warms.

A DETERMINATION OF THE MOTION BASED ON GNSS OBSERVATIONS BETWEEN 2000 AND 2021 BY USING THE IGS POINTS ON THE POLAR REGIONS

People are fascinated today more than ever by the polar regions of the Earth. One reason for this is that wide expanses of the Arctic and Antarctic have not been explored and are therefore still viewed as frontier regions. Another is that they both have very diverse histories with regard to their origins and ice formation. Their numerous aspects still pose many puzzles for science today. The regions of the Earth designated as polar are those areas located between the North or South Pole and the Arctic or Antarctic Circles, respectively. The northern polar region, called the Arctic, encompasses the Arctic Ocean and a portion of some surrounding land masses. The southern polar region, called the Antarctic, contains the continent of Antarctica and areas of the surrounding Southern Ocean. In this paper three tests (2000, 2010 and 2021) of continuous GNSS data recorded by 8 permanent International GPS Service (IGS) stations in both Polar Regions have been processed by using CSRS-PPP Software for geodetic networks. The results also show that all GNSS provide good visibility with low elevation angles, whereas with high elevation angles, which might be needed due to natural barriers, the GLONASS and other satellites provides the highest number of visible satellites. Consequently, the mean motion of the study area was found approximately 7–15 cm for horizontal components (X–Y) and 6 cm for vertical components (Ellipsoidal Height) on the eight IGS points in the both poles.

Tropospheric ozone retrieval by a combination of TROPOMI/S5P measurements with BASCOE assimilated data

Abstract. We present a new tropospheric ozone dataset based on TROPOspheric Monitoring Instrument (TROPOMI)/Sentinel-5 Precursor (S5P) total ozone measurements combined with stratospheric ozone data from the Belgian Assimilation System for Chemical ObsErvations (BASCOE) constrained by assimilating ozone observations from the Microwave Limb Sounder (MLS). The BASCOE stratospheric data are interpolated to the S5P observations and subtracted from the TROPOMI total ozone data. The difference is equal to the tropospheric ozone residual column from the surface up to the tropopause. The tropospheric ozone columns are retrieved at the full spatial resolution of the TROPOMI sensor (5.5×3.5 km2) with daily global coverage. Compared to the Ozone Mapping and Profiler Suite Modern-Era Retrospective analysis for Research and Applications 2 (OMPS-MERRA-2) data, a global mean positive bias of 3.3 DU is found for the analysed period April 2018 to June 2020. A small negative bias of about −0.91 DU is observed in the tropics relative to the operational TROPOMI tropical tropospheric data based on the convective cloud differential (CCD) algorithm throughout the same period. The new tropospheric ozone data (S5P-BASCOE) are compared to a set of globally distributed ozonesonde data integrated up to the tropopause level. We found 2254 comparisons with cloud-free TROPOMI observations within 25 km of the stations. In the global mean, S5P-BASCOE deviates by 2.6 DU from the integrated ozonesondes. Depending on the latitude the S5P-BASCOE deviate from the sondes and between −4.8 and 7.9 DU, indicating a good agreement. However, some exceptional larger positive deviations up to 12 DU are found, especially in the northern polar regions (north of 70∘). The monthly mean tropospheric column and time series for selected areas showed the expected spatial and temporal pattern, such as the wave one structure in the tropics or the seasonal cycle, including a summer maximum, in the mid-latitudes.

Connections between the Transient Polar Warming and Solstitial Pause on Mars

Observations show two different transient atmospheric events around the northern winter solstice on Mars: a warming of the polar lower atmosphere (100–10 Pa) and a reduction in the near-surface wave activity. Here we examine the cause of, and connections between, these two events, and how their occurrence may have changed in past climates using a suite of Mars general circulation model simulations. These simulations show that the polar warming and pause in wave activity are connected, and they occur when there are sufficiently large dust heating rates in the southern (summer) high latitudes, which drive an expansion of the downwelling branch of the Hadley cell into the northern polar region. This causes a poleward shift and weakening of the jet, a warming of the polar lower atmosphere, and reduced baroclinic instability and waves near the surface. The occurrence and strength of the polar warming and wave activity pause increase with obliquity and dust optical depth, with a stronger dependence on obliquity. In past climates with low obliquity the warming and pause are unlikely to occur, or will be very weak, whereas during times of high obliquity they will likely be strong and occur every winter, unless the atmosphere is nearly free of dust.

Simulation of Arctic sea ice within the DeepMIP Eocene ensemble: Thresholds, seasonality and factors controlling sea ice development

The early Eocene greenhouse climate maintained by high atmospheric CO2 concentrations serves as a testbed for future climate changes dominated by increasing CO2 forcing. In particular, the early Eocene Arctic region is important in the context of future CO2 driven climate warming in the northern polar region and associated shrinking Arctic sea ice. Here, we present early Eocene Arctic sea ice simulations carried out by six coupled climate models within the framework of the Deep-Time Model Intercomparison Project (DeepMIP). We find differences in sea ice responses to CO2 changes across the ensemble and compare the results with available proxy-based sea ice reconstructions from the Arctic Ocean. Most of the models simulate seasonal sea ice presence at high CO2 levels (≥ 840 ppmv = 3× pre-industrial (PI) level of 280 ppmv). However, the threshold when sea ice permanently disappears from the ocean varies considerably between the models (from <840 ppmv to >1680 ppmv). Based on a one-dimensional energy balance model analysis we find that the greenhouse effect likely caused by increased atmospheric water vapor concentration plays an important role in the inter-model spread in Arctic winter surface temperature changes in response to a CO2 rise from 1× to 3× the PI level. Furthermore, differences in simulated surface salinity in the Arctic Ocean play an important role in the control of local sea ice formation. These differences result from different implementations of river run-off between the models, but also from differences in the exchange of waters between a brackish Arctic and a more saline North Atlantic Ocean that are controlled by the width of the gateway between both basins. As there is no geological evidence for Arctic sea ice in the early Eocene, its presence in most of the simulations with 3× PI CO2 level indicates either a higher CO2 level and/or an overly weak polar sensitivity in these models.