Browsing by Subject "ICE"

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  • Bowles, N. E.; Snodgrass, C.; Gibbings, A.; Sanchez, J. P.; Arnold, J. A.; Eccleston, P.; Andert, T.; Probst, A.; Naletto, G.; Vandaele, A. C.; de Leon, J.; Nathues, A.; Thomas, I. R.; Thomas, N.; Jorda, L.; Da Deppo, V.; Haack, H.; Green, S. F.; Carry, B.; Hanna, K. L. Donaldson; Jorgensen, J. Leif; Kereszturi, A.; DeMeo, F. E.; Patel, M. R.; Davies, J. K.; Clarke, F.; Kinch, K.; Guilbert-Lepoutre, A.; Agarwal, J.; Rivkin, A. S.; Pravec, P.; Fornasier, S.; Granvik, M.; Jones, R. H.; Murdoch, N.; Joy, K. H.; Pascale, E.; Tecza, M.; Barnes, J. M.; Licandro, J.; Greenhagen, B. T.; Calcutt, S. B.; Marriner, C. M.; Warren, T.; Tosh, I. (2018)
    CASTAway is a mission concept to explore our Solar System's main asteroid belt. Asteroids and comets provide a window into the formation and evolution of our Solar System and the composition of these objects can be inferred from space-based remote sensing using spectroscopic techniques. Variations in composition across the asteroid populations provide a tracer for the dynamical evolution of the Solar System. The mission combines a long-range (point source) telescopic survey of over 10,000 objects, targeted close encounters with 10-20 asteroids and serendipitous searches to constrain the distribution of smaller (e.g. 10 m) size objects into a single concept. With a carefully targeted trajectory that loops through the asteroid belt, CASTAway would provide a comprehensive survey of the main belt at multiple scales. The scientific payload comprises a 50 cm diameter telescope that includes an integrated low-resolution (R = 30-100) spectrometer and visible context imager, a thermal (e.g. 6-16 mu m) imager for use during the flybys, and modified star tracker cameras to detect small (similar to 10 m) asteroids. The CASTAway spacecraft and payload have high levels of technology readiness and are designed to fit within the programmatic and cost caps for a European Space Agency medium class mission, while delivering a significant increase in knowledge of our Solar System. (C) 2017 COSPAR. Published by Elsevier Ltd. All rights reserved.
  • MacLennan, Eric; Toliou, Athanasia; Granvik, Mikael (2021)
    The near-Earth objects (NEOs) (3200) Phaethon and (155140) 2005 UD are thought to share a common origin, with the former exhibiting dust activity at perihelion that is thought to directly supply the Geminid meteor stream. Both of these objects currently have very small perihelion distances (0.140 au and 0.163 au for Phaethon and 2005 UD, respectively), which results in them having perihelion temperatures around 1000 K. A comparison between NEO population models to discovery statistics suggests that low-perihelion objects are destroyed over time by a, possibly temperature-dependent, mechanism that is efficient at heliocentric distances less than 0.3 au. By implication, the current activity from Phaethon is linked to the destruction mechanism of NEOs close to the Sun. We model the past thermal characteristics of Phaethon and 2005 UD using a combination of a thermophysical model (TPM) and orbital integrations of each object. Temperature characteristics such as maximum daily temperature, maximum thermal gradient, and temperature at different depths are extracted from the model, which is run for a predefined set of semi-major axis and eccentricity values. Next, dynamical integrations of orbital clones of Phaethon and 2005 UD are used to estimate the past orbital elements of each object. These dynamical results are then combined with the temperature characteristics to model the past evolution of thermal characteristics such as maximum (and minimum) surface temperature and thermal gradient. The orbital histories of Phaethon and 2005 UD are characterized by cyclic changes in.., resulting in perihelia values periodically shifting between present-day values and 0.3 au. Currently, Phaethon is experiencing relatively large degrees of heating when compared to the recent 20, 000 yr. We find that the subsurface temperatures are too large over this timescale for water ice to be stable, unless actively supplied somehow. The near-surface thermal gradients strongly suggest that thermal fracturing may be very effective at breaking down and ejecting dust particles. Observations by the DESTINY+ flyby mission will provide important constraints on the mechanics of dust-loss from Phaethon and, potentially, reveal signs of activity from 2005 UD. In addition to simulating the recent dynamical evolution of these objects, we use orbital integrations that start from the Main Belt to assess their early dynamical evolution (origin and delivery mechanism). We find that dwarf planet (2) Pallas is unlikely to be the parent body for Phaethon and 2005 UD, and it is more likely that the source is in the inner part of the asteroid belt in the families of, e.g., (329) Svea or (142) Polana.
  • Navarro-Almaida, D.; Le Gal, R.; Fuente, A.; Riviere-Marichalar, P.; Wakelam,; Cazaux, S.; Caselli, P.; Laas, J. C.; Alonso-Albi, T.; Loison, J. C.; Gerin, M.; Kramer, C.; Roueff, E.; Bachillerl, R.; Commercon, B.; Friesen, R.; Garcia-Burillo, S.; Goicoechea, J. R.; Giuliano, B. M.; Jimenez-Serram,; Kirk, J. M.; Lattanzi, M.; Malinen, J.; Marcelino, N.; Martin-Domenech, R.; Caro, G. M. Munoz; Pineda, J.; Tercero, B.; Trevino-Morales, S. P.; Roncero, O.; Hacar, A.; Tafalla, M.; Ward-Thompson, D. (2020)
    Context. Sulphur is one of the most abundant elements in the Universe. Surprisingly, sulphuretted molecules are not as abundant as expected in the interstellar medium and the identity of the main sulphur reservoir is still an open question.Aims. Our goal is to investigate the H2S chemistry in dark clouds, as this stable molecule is a potential sulphur reservoir.Methods. Using millimeter observations of CS, SO, H2S, and their isotopologues, we determine the physical conditions and H2S abundances along the cores TMC 1-C, TMC 1-CP, and Barnard 1b. The gas-grain model NAUTILUS is used to model the sulphur chemistry and explore the impact of photo-desorption and chemical desorption on the H2S abundance.Results. Our modeling shows that chemical desorption is the main source of gas-phase H2S in dark cores. The measured H2S abundance can only be fitted if we assume that the chemical desorption rate decreases by more than a factor of 10 when n(H) > 2 x 10(4). This change in the desorption rate is consistent with the formation of thick H2O and CO ice mantles on grain surfaces. The observed SO and H2S abundances are in good agreement with our predictions adopting an undepleted value of the sulphur abundance. However, the CS abundance is overestimated by a factor of 5-10. Along the three cores, atomic S is predicted to be the main sulphur reservoir.Conclusions. The gaseous H2S abundance is well reproduced, assuming undepleted sulphur abundance and chemical desorption as the main source of H2S. The behavior of the observed H2S abundance suggests a changing desorption efficiency, which would probe the snowline in these cold cores. Our model, however, highly overestimates the observed gas-phase CS abundance. Given the uncertainty in the sulphur chemistry, we can only conclude that our data are consistent with a cosmic elemental S abundance with an uncertainty of a factor of 10.
  • Helle, Inari; Mäkinen, Jussi Antti-Eerikki; Nevalainen, Maisa Katariina; Afenyo, Mawuli; Vanhatalo, Jarno (2020)
    Oil spills resulting from maritime accidents pose a poorly understood risk to the Arctic environment. We propose a novel probabilistic method to quantitatively assess these risks. Our method accounts for spatiotemporally varying population distributions, the spreading of oil, and seasonally varying species-specific exposure potential and sensitivity to oil. It quantifies risk with explicit uncertainty estimates, enables one to compare risks over large geographic areas, and produces information on a meaningful scale for decision-making. We demonstrate the method by assessing the short-term risks oil spills pose to polar bears, ringed seals, and walrus in the Kara Sea, the western part of the Northern Sea Route. The risks differ considerably between species, spatial locations, and seasons. Our results support current aspirations to ban heavy fuel oil in the Arctic but show that we should not underestimate the risks of lighter oils either, as these oils can pollute larger areas than heavier ones. Our results also highlight the importance of spatially explicit season-specific oil spill risk assessment in the Arctic and that environmental variability and the lack of data are a major source of uncertainty related to the oil spill impacts.
  • Lehmkuehler, Felix; Forov, Yury; Buening, Thomas; Sahle, Christoph J.; Steinke, Ingo; Julius, Karin; Buslaps, Thomas; Tolan, Metin; Hakala, Mikko; Sternemann, Christian (2016)
    We studied the structure and energetics of supercooled water by means of X-ray Raman and Compton scattering. Under supercooled conditions down to 255 K, the oxygen K-edge measured by X-ray Raman scattering suggests an increase of tetrahedral order similar to the conventional temperature effect observed in non-supercooled water. Compton profile differences indicate contributions beyond the theoretically predicted temperature effect and provide a deeper insight into local structural changes. These contributions suggest a decrease of the electron mean kinetic energy by 3.3 +/- 0.7 kJ (mol K)(-1) that cannot be modeled within established water models. Our surprising results emphasize the need for water models that capture in detail the intramolecular structural changes and quantum effects to explain this complex liquid.
  • Majaneva, Markus; Enberg, Sara; Autio, Riitta; Blomster, Jaanika; Rintala, Janne-Markus (2019)
    The green algae Mamiellophyceae are a group of marine picoeukaryotes. We studied the succession of Mamiellophyceae in the Baltic Sea water column and ice from autumn to summer, using the hypervariable V4 region of the 18S ribosomal RNA (18S rRNA) gene. We show that species of Mamiellophyceae shift in seasonal predominance and that different species characterize sea ice, under-ice water, and the water column in the Baltic Sea.
  • Svensson, J.; Strom, J.; Hansson, M.; Lihavainen, H.; Kerminen, V-M (2013)
  • Dias, Fabio Boeira; Fiedler, R.; Marsland, S. J.; Domingues, C. M.; Clement, L.; Rintoul, S. R.; Mcdonagh, E. L.; Mata, M. M.; Savita, A. (2020)
    Ocean heat storage due to local addition of heat ("added'') and due to changes in heat transport ("redistributed'') were quantified in ocean-only 2xCO2 simulations. While added heat storage dominates globally, redistributionmakes important regional contributions, especially in the tropics. Heat redistribution is dominated by circulation changes, summarized by the super-residual transport, with only minor effects from changes in vertical mixing. While previous studies emphasized the contribution of redistribution feedback at high latitudes, this study shows that redistribution of heat also accounts for 65% of heat storage at low latitudes and 25% in the midlatitude (35 degrees-50 degrees S) Southern Ocean. Tropical warming results from the interplay between increased stratification and equatorward heat transport by the subtropical gyres, which redistributes heat from the subtropics to lower latitudes. The Atlantic pattern is remarkably distinct from other basins, resulting in larger basin-average heat storage. Added heat storage is evenly distributed throughout midlatitude Southern Ocean and dominates the total storage. However, redistribution stores heat north of the Antarctic Circumpolar Current in the Atlantic and Indian sectors, having an important contribution to the peak of heat storage at 45 degrees S. Southern Ocean redistribution results from intensified heat convergence in the subtropical front and reduced stratification in response to surface heat, freshwater, and momentum flux perturbations. These results highlight that the distribution of ocean heat storage reflects both passive uptake of heat and active redistribution of heat by changes in ocean circulation processes. The redistributed heat transportmust therefore be better understood for accurate projection of changes in ocean heat uptake efficiency, ocean heat storage, and thermosteric sea level.
  • Zhang, Yuemei; Ertbjerg, Per (2019)
    The role of protein denaturation in formation of thaw loss is currently not well understood. This study investigated denaturation of myofibrillar and sarcoplasmic proteins of pork loins caused by freezing-thawing in relation to freezing rate. Compared to fast freezing, slow freezing caused 28% larger thaw loss, decreased water-holding capacity of myofibrils and increased surface hydrophobicity, indicating more pronounced denaturation of myofibrillar proteins. We here propose a model: In slow freezing protons are concentrated in the unfrozen water resulting in reduced pH in proximity of structural proteins causing protein denaturation. In parallel, large ice crystals are formed outside of muscle fibers resulting in transversal shrinkage. In fast freezing small ice crystals trap protons and cause less severe protein denaturation and reduced thaw loss. Differential scanning calorimetry and tryptophan fluorescence spectra indicated sarcoplasmic protein denaturation in drip due to freezing-thawing. However, sarcoplasmic protein denaturation was independent of freezing rate.
  • Asmi, Eija; Neitola, Kimmo; Teinila, Kimmo; Rodriguez, Edith; Virkkula, Aki; Backman, John; Bloss, Matthew; Jokela, Jesse; Lihavainen, Heikki; De Leeuw, Gerrit; Paatero, Jussi; Aaltonen, Veijo; Mei, Miguel; Gambarte, Gonzalo; Copes, Gustavo; Albertini, Marco; Perez Fogwill, German; Ferrara, Jonathan; Elena Barlasina, Maria; Sanchez, Ricardo (2018)
    Aerosol particle optical properties were measured continuously between years 2013-2015 at the Marambio station in the Antarctic Peninsula. Annual cycles of particle scattering and absorption were studied and explained using measured particle chemical composition and the analysis of air mass transport patterns. The particle scattering was found elevated during the winter but the absorption did not show any clear annual cycle. The aerosol single scattering albedo at lambda = 637 nm was on average 0.96 +/- 0.10, with a median of 0.99. Aerosol scattering Angstrom exponent increased during summer, indicating an increasing fraction of fine mode particles. The aerosol was mainly composed of sea salt, sulphate and crustal soil minerals, and most of the particle mass were in the coarse mode. Both the particle absorption and scattering were increased during high wind speeds. This was explained by the dominance of the primary marine sea-spray and wind-blown soil dust sources. In contrast, the back-trajectory analysis suggested that long-range transport has only a minor role as a source of absorbing aerosol at the peninsula.
  • Moisseev, Dmitri; von Lerber, Annakaisa; Tiira, Jussi (2017)
    Ground-based observations of ice particle size distribution and ensemble mean density are used to quantify the effect of riming on snowfall. The rime mass fraction is derived from these measurements by following the approach that is used in a single ice-phase category microphysical scheme proposed for the use in numerical weather prediction models. One of the characteristics of the proposed scheme is that the prefactor of a power law relation that links mass and size of ice particles is determined by the rime mass fraction, while the exponent does not change. To derive the rime mass fraction, a mass-dimensional relation representative of unrimed snow is also determined. To check the validity of the proposed retrieval method, the derived rime mass fraction is converted to the effective liquid water path that is compared to microwave radiometer observations. Since dual-polarization radar observations are often used to detect riming, the impact of riming on dual-polarization radar variables is studied for differential reflectivity measurements. It is shown that the relation between rime mass fraction and differential reflectivity is ambiguous, other factors such as change in median volume diameter need also be considered. Given the current interest on sensitivity of precipitation to aerosol pollution, which could inhibit riming, the importance of riming for surface snow accumulation is investigated. It is found that riming is responsible for 5% to 40% of snowfall mass. The study is based on data collected at the University of Helsinki field station in Hyytiala during U.S. Department of Energy Biogenic Aerosols Effects on Clouds and Climate (BAECC) field campaign and the winter 2014/2015. In total 22 winter storms were analyzed, and detailed analysis of two events is presented to illustrate the study.
  • Ruosteenoja, Kimmo; Jylhä, Kirsti; Räisänen, Jouni; Mäkelä, Antti (2018)
    The commentators regard a categorical truncation of supersaturations with respect to ice in climate model output as an inappropriate solution to the supersaturation issue. This view is supported by observational evidence from the East Antarctic Plateau. We accept this criticism to a certain degree. Even so, it is necessary to make a clear distinction between the true supersaturations measured in the atmosphere and the spurious supersaturations existing in archived model output data sets: the latter result, for example, from inconsistencies in the interpolation of temperature and specific humidity to the near-surface level. In the CMIP5 model output data sets, the largest relative humidities in near-surface air are far above those observed. Moreover, supersaturations given at the 2-m height are generally much larger than those at the lowermost tropospheric isobaric levels. Projections of relative humidity for the future may be considerably distorted if founded on unmodified output data sets.
  • Orme, Lisa Claire; Crosta, Xavier; Miettinen, Arto; Divine, Dmitry; Husum, Katrine; Isaksson, Elisabeth; Wacker, Lukas; Mohan, Rahul; Ther, Olivier; Ikehara, Minoru (2020)
    Centennial- and millennial-scale variability of Southern Ocean temperature over the Holocene is poorly known, due to both short instrumental records and sparsely distributed high-resolution temperature reconstructions, with evidence for past temperature variations in the region coming mainly from ice core records. Here we present a high-resolution (similar to 60 year), diatom-based sea surface temperature (SST) reconstruction from the western Indian sector of the Southern Ocean that spans the interval 14.2 to 1.0 ka (calibrated kiloyears before present). During the late deglaciation, the new SST record shows cool temperatures at 14.2-12.9 ka and gradual warming between 12.9 and 11.6 ka in phase with atmospheric temperature evolution. This supports the evolution of the Southern Ocean SST during the deglaciation being linked with a complex combination of processes and drivers associated with reorganisations of atmospheric and oceanic circulation patterns. Specifically, we suggest that Southern Ocean surface warming coincided, within the dating uncertainties, with the reconstructed slowdown of the Atlantic Meridional Overturning Circulation (AMOC), rising atmospheric CO2 levels, changes in the southern westerly winds and enhanced upwelling. During the Holocene the record shows warm and stable temperatures from 11.6 to 8.7 ka followed by a slight cooling and greater variability from 8.7 to 1 ka, with a quasi-periodic variability of 200-260 years identified by spectral analysis. We suggest that the increased variability during the mid- to late Holocene reflects the establishment of centennial variability in SST connected with changes in the high-latitude atmospheric circulation and Southern Ocean convection.
  • Svensson, Jonas; Virkkula, Aki; Meinander, Outi; Kivekäs, Niku; Hannula, Henna-Reetta; Järvinen, Onni; Peltoniemi, Jouni I.; Gritsevich, Maria; Heikkila, Anu; Kontu, Anna; Neitola, Kimmo; Brus, David; Dagsson-Waldhauserova, Pavla; Anttila, Kati; Vehkamäki, Marko; Hienola, Anca; De Leeuw, Gerrit; Lihavainen, Heikki (2016)
    Soot has a pronounced effect on the cryosphere and experiments are still needed to reduce the associated uncertainties. This work presents a series of experiments to address this issue, with soot being deposited onto a natural snow surface after which the albedo changes were monitored. The albedo reduction was the most pronounced for the snow with higher soot content, and it was observed immediately following soot deposition. Compared with a previous laboratory study the effects of soot on the snow were not as prominent in outdoor conditions. During snowmelt, about 50% of the originally deposited soot particles were observed to remain at the snow surface. More detailed experiments are however needed to better explain soot's effect on snow and to better quantify this effect. Our albedo versus soot parameterization agreed relatively well with previously published relationships.
  • Virta, Leena; Soininen, Janne; Norkko, Alf (2020)
    The global biodiversity loss has raised interest in the different facets of diversity, and the importance of diversity for ecosystem functions has been recognized. However, our knowledge on seasonal and inter-annual variation in the composition and diversity of communities is still poor. Here, we investigated the seasonal and inter-annual changes in taxonomic and functional community composition and diversity of benthic diatoms in a coastal habitat of the northern Baltic Sea, where seasonal and inter-annual variation of climate is pronounced. We found that the taxonomic and functional alpha diversity remained stable at seasonal and inter-annual level despite strong changes in community composition. However, alpha diversity decreased during an exceptionally warm winter possibly due to disturbances induced by the lack of ice. This may suggest that climate warming and consequently limited ice cover will affect the diversity of benthic communities.
  • Aalto, J.; Karjalainen, O.; Hjort, J.; Luoto, M. (2018)
    Mean annual ground temperature (MAGT) and active layer thickness (ALT) are key to understanding the evolution of the ground thermal state across the Arctic under climate change. Here a statistical modeling approach is presented to forecast current and future circum-Arctic MAGT and ALT in relation to climatic and local environmental factors, at spatial scales unreachable with contemporary transient modeling. After deploying an ensemble of multiple statistical techniques, distance-blocked cross validation between observations and predictions suggested excellent and reasonable transferability of the MAGT and ALT models, respectively. The MAGT forecasts indicated currently suitable conditions for permafrost to prevail over an area of 15.1 +/- 2.8 x 10(6) km(2). This extent is likely to dramatically contract in the future, as the results showed consistent, but region-specific, changes in ground thermal regime due to climate change. The forecasts provide new opportunities to assess future Arctic changes in ground thermal state and biogeochemical feedback.
  • van Schaik, Ivo N.; Bril, Vera; van Geloven, Nan; Hartung, Hans-Peter; Lewis, Richard A.; Sobue, Gen; Lawo, John-Philip; Praus, Michaela; Mielke, Orell; Durn, Billie L.; Cornblath, David R.; Merkies, Ingemar S. J.; PATH Study Grp; Saarela, Mika (2018)
    Background Approximately two-thirds of patients with chronic inflammatory demyelinating polyneuropathy (CIDP) need long-term intravenous immunoglobulin. Subcutaneous immunoglobulin (SCIg) is an alternative option for immunoglobulin delivery, but has not previously been investigated in a large trial of CIDP. The PATH study compared relapse rates in patients given SCIg versus placebo. Methods Between March 12, 2012, and Sept 20, 2016, we studied patients from 69 neuromuscular centres in North America, Europe, Israel, Australia, and Japan. Adults with definite or probable CIDP who responded to intravenous immunoglobulin treatment were eligible. We randomly allocated participants to 0.2 g/kg or 0.4 g/kg of a 20% SCIg solution (IgPro20) weekly versus placebo (2% human albumin solution) for maintenance treatment for 24 weeks. We did randomisation in a 1: 1:1 ratio with an interactive voice and web response system with a block size of six, stratified by region (Japan or non-Japan). The primary outcome was the proportion of patients with a CIDP relapse or who were withdrawn for any other reason during 24 weeks of treatment. Patients, caregivers, and study personnel, including those assessing outcomes, were masked to treatment assignment. Analyses were done in the intention-to-treat and per-protocol sets. This trial is registered with ClinicalTrials. gov, number NCT01545076. Findings In this randomised, double-blind, placebo-controlled trial, we randomly allocated 172 patients: 57 (33%) to the placebo group, 57 (33%) to the low-dose group, and 58 (34%) to the high-dose group. In the intention-to-treat set, 36 (63% [95% CI 50-74]) patients on placebo, 22 (39% [27-52]) on low-dose SCIg, and 19 (33% [22-46]) on high-dose SCIg had a relapse or were withdrawn from the study for other reasons (p=0.0007). Absolute risk reductions were 25% (95% CI 6-41) for low-dose versus placebo (p=0.007), 30% (12-46) for high-dose versus placebo (p=0.001), and 6% (-11 to 23) for high-dose versus low-dose (p=0.32). Causally related adverse events occurred in 47 (27%) patients (ten [18%] in the placebo group, 17 [30%] in the low-dose group, and 20 [34%] in the high-dose group). Six (3%) patients had 11 serious adverse events: one (2%) patient in the placebo group, three (5%) in the low-dose group, and two (3%) in the high-dose group; only one (an acute allergic skin reaction in the low-dose group) was assessed to be causally related. Interpretation This study, which is to our knowledge, the largest trial of CIDP to date and the first to study two administrations of immunoglobulins and two doses, showed that both doses of SCIg IgPro20 were efficacious and well tolerated, suggesting that SCIg can be used as a maintenance treatment for CIDP.
  • Ruosteenoja, Kimmo; Jylha, Kirsti; Räisänen, Jouni; Mäkelä, Antti (2017)
    In 17 out of the 29 Phase 5 of Coupled Model Intercomparison Project (CMIP5) climate models examined in this work, near-surface air relative humidity (RH) frequently exceeded 100% with respect to ice in polar areas in winter. The degree of supersaturation varied considerably across the models, and the same evidently applies to the causes of the phenomenon. Consultations with the modeling groups revealed three categories of explanations for supersaturation occurrence: specification of RH with respect to ice rather than liquid water; inconsistencies in the determination of specific humidity and air temperature for the near-surface level; and the nonlinearity of saturated specific humidity as a function of temperature. Modeled global warming tended to reduce the artificial supersaturations, inducing a spurious negative trend in the future RH change. For example, over East Antarctica under Representative Concentration Pathway 8.5, the multimodel mean RH would decrease by about 10% by the end of the ongoing century. Truncation of overly high RHs to a maximum value of 100% cut the RH response close to zero. In Siberia and northern North America, truncation even reversed the sign of the response. The institutes responsible for the CMIP6 model experiments should be aware of the supersaturation issue, and the algorithms used to produce near-surface RH should be developed to eliminate the problem before publishing the RH output data. Plain Language Summary In the atmosphere, observed relative humidity is between 0% and 100%. However, some climate models produce spurious higher than 100% humidities. The problem only concerns polar areas in winter. As temperatures rise in the future, such model-produced excessively high relative humidities partially vanish. Unfortunately, this induces a spurious negative trend in the future humidity projections. Such a spurious component in the simulated trend complicates discerning the real physically based trend. The spurious trend could be eliminated by truncating the portion of relative humidity that exceeds 100% in the model output data. Even so, this may not be fully adequate for elaborating reliable humidity projections for polar areas. Therefore, it is highly desirable that the relative humidity calculations in the climate models would be developed so that unrealistic relative humidities would not occur in future model generations. We emphasize that this issue only concerns humidity projections and does not affect model-based predictions of temperature and precipitation change.