适应极地快速变化海冰模式的研发与挑战

极地海冰是地球气候系统的重要组成部分,也是气候环境变化的指示器和放大器.极地海冰复杂的多尺度物理过程和极地观测资料的匮乏,给海冰模式的研发带来了巨大的挑战.在过去的半个多世纪中,大气-海冰-海洋的复杂相互作用和冰内物理过程在海冰模式中的数学描述取得了重大的进展,但海冰模式对一些重要物理过程的描述仍很不完善,尤其是近年来...     

Variations of sea ice temperature from CHINARE 2003 and its application on sea ice model evaluation

Variation of vertical profiles of sea ice temperature and adjacent atmosphere and ocean temperatures were measured by ice drifting buoys deployed in the northeast Chukchi Sea as part of the 2003 Chinese Arctic Research Expedition.The buoy observations (September 2003 to February 2005) show that the cooling of the ice began in late September,propagated down through the ice,reaching the bottom of the ice in December,and continued throughout the winter.In winter 2003/04,some obvious warmings were observed in the upper portion of the ice in response to major warmings in the overlying atmosphere associated with the periodicity of storms in the northeast Chukchi Sea.It is found that the melt season at the buoy site in 2004 was about 15% longer than normal.The buoy observed vertical ice temperature profiles were used as a diagnostic for sea ice model evaluation.The results show that the simulated ice temperature profiles have large discrepancies as compared with the observations.     

Geometric and aerodynamic roughness of sea ice

The aerodynamic drag of Arctic sea ice is calculated using surface data, measured by an airborne laser altimeter and a digital camera in the marginal ice zone of Fram Strait. The influence of the surface morphology on the momentum transfer under neutral thermal stratification in the atmospheric boundary layer is derived with the aid of model concepts, based on the partitioning of the surface drag into a form drag and a skin drag. The drag partitioning concept pays attention to the probability density functions of the geometric surface parameters. We found for the marginal ice zone that the form drag, caused by floe edges, can amount to 140% of the skin drag, while the effect of pressure ridges never exceeded 40%. Due to the narrow spacing of obstacles, the skin drag is significantly reduced by shadowing effects on the leeward side of floe edges. For practical purposes, the fractional sea-ice coverage can be used to parameterize the drag coefficientC _dn, related to the 10 m-wind. C _dnincreases from 1.2 · 10^-3 over open water to 2.8 · 10^-3 for 55% ice coverage and decreases to 1.5 · 10^-3 for 100% ice coverage.Aircraft turbulence measurements are used to compare the model values of C _dnwith measureents. The correlation between measured and modelled drag coefficients results in r ² = 0.91, where r is the correlation coefficient.     

大气河对南极冰盖及海冰的影响

南极冰盖与海冰对全球气候具有重要影响。大气河作为高纬度地区经向水汽输送的重要途径,其对南极冰盖与海冰的影响在近年来愈发受到重视。南极大气河通常形成于高压脊(阻塞高压)与温带气旋之间的强向极经向输送带内。低频的大气河活动为南极带来强降雪,有利于冰盖质量增加。然而,强暖湿水汽侵入同时会导致表面融化、冰架崩解和极端高温,对冰盖质量存在潜在负贡献。大气河携带极端暖湿水汽与强风通过热力与动力过程导致海冰密集度下降。目前,大气河的识别算法仍不完善,其对液态降水的直接影响、与南大洋的相互作用等仍不清楚,需要进一步明晰大气河对南极冰盖与海冰的影响机制,以准确预估未来大气河对南极冰盖物质平衡与海冰变化的作用。     

Radiometer studies of low-salinity sea ice

Theoretical and experimental studies of ultra-high-frequency (UHF) and microwave radiometry to sense remotely the thickness and other characteristics of low-salinity (less than one per mille) sea ice are described. The experimental studies used a 600-MHz and a multichannel, multibeam, 4.7-GHz radiometer carried by a helicopter to measure the brightness temperature of different types of sea ice in the Gulf of Bothnia in 1975 and 1976.The developed theory and experiments show that the brightness temperature of low-salinity sea ice oscillates as a function of ice thickness at UHF frequencies. Due to higher attenuation, the oscillations quickly die away at 4.7 GHz and the brightness temperature reaches an almost constant value when the thickness exceeds a few decimetres. By using a three-channel UHF radiometer with suitably selected center frequencies, the oscillations can be reduced and the effective brightness temperature will grow more linearly with the ice thickness.Experiments show that ice ridges appear as thick ice at 600 MHz and as thinner ice at 4.7 GHz, thus allowing them to be detected by radio techniques.     

Barents-Kara sea ice and European winters in EC-Earth

Climate Dynamics - The potential link between decreasing Barents-Kara sea ice and cold winters in Europe is investigated using the enhanced resolution (horizontal atmospheric resolution of $$\sim...     

On the interannual variability of arctic sea‐level pressure and sea ice

Abstract

Monthly mean sea‐level pressure (SLP) data from the Northern Hemisphere for the period January 1952‐December 1987 are analysed. Fluctuations in this field over the Arctic on interannual time‐scales and their statistical association with fluctuations farther south are determined. The standard deviation of the interannual variability is largest compared with that of the annual cycle along the seaboards of the major land masses. The SLP anomalies are generally in phase over the entire Arctic Basin and extend south over the northern Russia and Canada, but tend to be out of phase with fluctuations at mid‐latitudes. The anomalies are most closely associated with fluctuations over the North Atlantic and Europe except near the Chukchi Sea to the north of Bering Strait. The associations with the North Pacific fluctuations become increasingly more prominent at most Arctic sites (e.g. the Canadian Arctic Archipelago) as the time‐scale increases.

Associations between the SLP fluctuations and atmospheric indices that represent processes affecting sea‐ice drift (wind stress and wind stress curl) are determined. In every case local associations dominate, but some remote ones are also evident. For example, changes in the magnitude of the wind stress curl over the Beaufort Sea are increased if the atmospheric circulation over the North Pacific is intensified; wind stress over the region where sea ice is exchanged between the Beaufort Gyre and the Transpolar Drift Stream is modulated by both the Southern and North Atlantic Oscillations.

Severe sea‐ice conditions in the Greenland Sea (as measured by the Koch Ice Index) coincide with a weakened atmospheric circulation over the North Atlantic.     

Regional variability of Antarctic sea ice extent

Interannual and seasonal variability of regional distribution of Antarctic sea ice extent is studied using monthly mean data on sea ice concentration in 1970-2012. The correlation is estimated between the variations in the area of floating ice in West and East Antarctica as well as in the Atlantic, Pacific, and Indian sectors of the Southern Ocean and the indices of atmospheric circuiation in the Southern Hemisphere.     

Parameterizing turbulent exchange over sea ice: the ice station weddell results

A 4-month deployment on Ice Station Weddell (ISW) in the western Weddell Sea yielded over 2000 h of nearly continuous surface-level meteorological data, including eddy-covariance measurements of the turbulent surface fluxes of momentum, and sensible and latent heat. Those data lead to a new parameterization for the roughness length for wind speed, z₀, for snow-covered sea ice that combines three regimes: an aerodynamically smooth regime, a high-wind saltation regime, and an intermediate regime between these two extremes where the macroscale or `permanent' roughness of the snow and ice determines z₀. Roughness lengths for temperature, z_T, computed from this data set corroborate the theoretical model that Andreas published in 1987. Roughness lengths for humidity,z_Q, do not support this model as conclusively but are all, on average, within an order of magnitude of its predictions. Only rarely arez_Tand z_Q equal to z₀. These parameterizations have implications for models that treat the atmosphere-ice-ocean system.     

Arctic sea ice and Eurasian climate: A review

The Arctic plays a fundamental role in the climate system and has shown significant climate change in recent decades,including the Arctic warming and decline of Arctic sea-ice extent and thickness. In contrast to the Arctic warming and reduction of Arctic sea ice, Europe, East Asia and North America have experienced anomalously cold conditions, with record snowfall during recent years. In this paper, we review current understanding of the sea-ice impacts on the Eurasian climate.Paleo, observational and modelling studies are covered to summarize several major themes, including: the variability of Arctic sea ice and its controls; the likely causes and apparent impacts of the Arctic sea-ice decline during the satellite era,as well as past and projected future impacts and trends; the links and feedback mechanisms between the Arctic sea ice and the Arctic Oscillation/North Atlantic Oscillation, the recent Eurasian cooling, winter atmospheric circulation, summer precipitation in East Asia, spring snowfall over Eurasia, East Asian winter monsoon, and midlatitude extreme weather; and the remote climate response(e.g., atmospheric circulation, air temperature) to changes in Arctic sea ice. We conclude with a brief summary and suggestions for future research.     

The effects of aggressive mitigation on steric sea level rise and sea ice changes

With an increasing political focus on limiting global warming to less than 2 °C above pre-industrial levels it is vital to understand the consequences of these targets on key parts of the climate system. Here, we focus on changes in sea level and sea ice, comparing twenty-first century projections with increased greenhouse gas concentrations (using the mid-range IPCC A1B emissions scenario) with those under a mitigation scenario with large reductions in emissions (the E1 scenario). At the end of the twenty-first century, the global mean steric sea level rise is reduced by about a third in the mitigation scenario compared with the A1B scenario. Changes in surface air temperature are found to be poorly correlated with steric sea level changes. While the projected decreases in sea ice extent during the first half of the twenty-first century are independent of the season or scenario, especially in the Arctic, the seasonal cycle of sea ice extent is amplified. By the end of the century the Arctic becomes sea ice free in September in the A1B scenario in most models. In the mitigation scenario the ice does not disappear in the majority of models, but is reduced by 42 % of the present September extent. Results for Antarctic sea ice changes reveal large initial biases in the models and a significant correlation between projected changes and the initial extent. This latter result highlights the necessity for further refinements in Antarctic sea ice modelling for more reliable projections of future sea ice.     

Climate model sensitivity to sea ice albedo parameterization

Summary Three one-year experimental simulations with the National Center for Atmospheric Research Community Climate Model (NCAR CCM) were performed with three sea ice albedo parameterizations and compared with control run results to examine their impact on polar surface temperature, planetary albedo and clouds. The first integration utilized sea ice albedos of the Arctic Basin for the spring and summer of 1977 derived from defence Meteorological Satellite Imagery (DMSP). The second simulation employed prescribed lead and melt pond fractions and an albedo weighting scheme. The third simulation involved the coupling of an interactive sea ice/snow albedo parameterization made a function of surface state.Results show that prescribed, and assumed true satellite sea ice albedos produced higher planetary albedos than those calculated with the standard CCM sea ice albedo scheme in the control run. As a result, lower temperatures (up to 0.5 K) and increased cloudiness are generated for the Arctic region. The standard CCM sea ice albedo scheme is used as an adjustment to maintain normal temperatures for the polar oceans. The radiative impact of leads and melt ponds warmed sea ice regions only for short time periods. The third scheme generated markedly lower planetary albedos (reductions of 0.07 to 0.17) and higher surface temperatures (up to 2.0 K) than control values.The CCM simulates a gradual decrease in spring and summer Arctic cloud cover whereas observations show a sharp spring increase. Examination of the CCM code, particularly the cloud parameterization, is required to address this problem.With 12 Figures     

Properties of adjoint sea ice sensitivities to atmospheric forcing and implications for the causes of the long term trend of Arctic sea ice

Based on adjoint sensitivities of the coupled Massachusetts Institute of Technology ocean–sea ice circulation model, the potential influence of thermodynamic atmospheric forcing on the interannual variability of the September sea ice area (AREA) and volume (VOLUME) in the Arctic is investigated for the three periods 1980–1989, 1990–1999 and 2000–2009. Sensitivities suggest that only large forcing anomalies prior to the spring melting onset in May can influence the September sea ice characteristics while even small changes in the atmospheric variables during subsequent months can significantly influence September sea ice state. Specifically, AREA close to the ice edge in the Arctic seas is highly sensitive to thermodynamic atmospheric forcing changes from June to July. In contrast, VOLUME is highly sensitive to atmospheric temperature changes occurring during the same period over the central parts of the Arctic Ocean. A comparison of the sea ice conditions and sensitivities during three different periods reveals that, due to the strong decline of sea ice concentration and sea ice thickness, sea ice area became substantially more sensitive to the same amplitude thermodynamic atmospheric forcing anomalies during 2000–2009 relative to the earlier periods. To obtain a quantitative estimate of changes that can be expected from existing atmospheric trends, adjoint sensitivities are multiplied by monthly temperature differences between 1980s and two following decades. Strongest contributions of surface atmospheric temperature differences to AREA and VOLUME changes are observed during May and September. The strongest contribution from the downward long-wave heat flux to AREA changes occurs in September and to VOLUME changes in July–August. About 62 % of the AREA decrease simulated by the model can be explained by summing all contributions to the thermodynamic atmospheric forcing. The changing sea ice state (sensitivity) is found to enhance the decline and accounts for about one third of the explained reduction. For the VOLUME decrease, the explained fraction of the decrease is only about 37 %.     

On the mass and heat budget of arctic sea ice

Summary Measurements during the drift of US Drifting Station A show an annual mass increase of old ice consisting of 12.5 g/cm² snow and 52 g/cm² bottom accretion. During the summer seasons 1957 and 1958 an amount of 19.2 and 41.4 g/cm² respectively, was lost by surface ablation. The ratio of ablation on elevated dry surface and in meltwater ponds is 1:2.5. The average pond area was about 30%. Bottom ablation by heat transfer from the ocean was found to be 22 cm (July to Aug./Sept.).Methods of measuring mass changes are described. In view of their importance as a means of checking the computed heat budget their accuracy is discussed in detail.The heat budget is computed for a selected period during the height of the melt season. The average daily totals are, in cal/cm²: +142 from net short wave radiation –8 from net long wave radiation, +9 from turbulent heat transfer, and –11 from evaporation. The mean daily surface ablation is 0.8 cm. About 90% of it is due to the absorption of short wave radiationOnly 62% of the total heat supply are transformed at the surface. 38% are transmitted into the ice and mainly used to increase the brine volume. The vertical distribution of this energy was used to compute the extinction coefficient for short wave radiation. From 40 to 150 cm depth it is 0.015 cm^–1, somewhat smaller than that of glacier ice.The heat used during the summer to increase the brine volume in the ice acts as a reserve of latent heat during the cooling season. By the time an ice sheet of 300 cm thickness reaches its minimum temperature in March, 3000 cal/cm² have been removed to freeze the brine in the interior of the ice and the meltwater ponds, and 1700 cal/cm² to lower the ice temperature. Based upon the observed mass and temperature changes the total heat exchange at the upper and lower boundary is estimated. During the period May–August the upper boundary received 8.3 kcal/cm², while during the period September–April 12.8 kcal/cm² were given off to the atmosphere. The results are compared with those ofYakovlev, and considerable disagreement is found with respect to the amounts of heat involved in evaporation and in changes of ice temperature (heat reserve).

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Zusammenfassung Beobachtungen während der Drift von US Drifting Station A zeigen an altem Eis einen jährlichen Massenzuwachs von 12,5 g/cm² Schnee und 52 g/cm² Eis an der Unterseite. Während der Schmelzperioden 1957 und 1958 betrug der Massenverlust an der Oberseite 19,2 bzw. 41,4 g/cm². Das Verhältnis der Ablation auf trockenen Eisflächen zu der in Wassertümpeln beträgt etwa 1:2,5. Etwa 30% der Gesamtfläche werden im Sommer von den Wassertümpeln eingenommen. Die Ablation an der Unterseite durch Wärmezufuhr vom Meer betrug etwa 22 cm (Juli bis August/September).Die Methoden der Messung des Massenhaushalts werden beschrieben. In Anbetracht ihrer Bedeutung als Kontrolle des berechneten Wärmehaushalts wird ihre Genauigkeit näher untersucht.Die Wärmebilanz der Eisoberfläche wird für einen ausgewählten Zeitraum während des Maximums der Ablationsperiode berechnet. Es ergeben sich folgende mittlere Tagessummen in cal/cm²: +142 kurzwellige Strahlungsbilanz, –8 langwellige Strahlungsbilanz, +9 Konvektionswärmestrom. –11 Verdunstung. Die mittlere tägliche Oberflächen-Ablation betrug in dieser Zeit 0,8 cm. Etwa 90% davon werden durch Absorption kurzwelliger Strahlung verursacht.Nur 62% des gesamten Wärmeangebotes werden an der Oberfläche umgesetzt. 38% gelangen in tiefere Schichten und werden dort hauptsächlich zur Vergrößerung des Volumens der Salzlösung verwendet. Die vertikale Verteilung dieser Energie wird zur Berechnung des Extinktionskoeffizienten für kurzwellige Strahlung herangezogen. In einer Tiefe von 40 bis 150 cm ergibt sich ein Wert von 0,015 cm^–1, etwas weniger als in Gletschereis.Die Wärmemenge, welche im Sommer zur Erhöhung der Eistemperatur und der damit verbundenen Vergrößerung des Volumens der Salzlösung aufgewendet wurde, dient während der Abkühlungsperiode als Wärmereserve. Von ihrem Beginn bis zur Erreichung minimaler Eistemperaturen in März werden einer 3 m dicken Eisdecke 3000 cal/cm² an latenter Wärme (Verkleinerung des Volumens der Salzlösung und Gefrieren der Schmelzwassertümpel) und 1700 cal/cm² mit der reinen Temperaturerniedrigung entzogen. Auf Grund der beobachteten Massen- und Temperaturänderungen der Eisdecke wird der gesamte Wärmeumsatz an ihren Grenzflächen abgeschätzt. Während der Periode Mai bis August erhält die Oberfläche des Eises 8,3 kcal/cm² während in der Periode September bis April 12,8 kcal/cm² an die Atmosphäre abgegeben werden. Die Resultate werden mit denen vonYakovlev verglichen, wobei sich beträchtliche Unterschiede in den Beträgen der Verdunstung und der Wärmereserve der Eisdecke ergeben. Im Zusammenhang mit den unterschiedlichen Beträgen der Wärmereserve wird die spezifische Wärme des Meereises näher diskutiert.

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Résumé Les observations faites lors de la dérive du US drifting station A font apparaître un accroissement annuel de masse de la banquise de 12,5 g/cm² sous forme de niege et de 52 g/cm² par congélation à la base. Pendant les périodes de fonte de 1957 et de 1958, la perte de masse à la surface fut de 19,2 et 41,4 g/cm² respectivement. Le rapport de l'ablation sur la glace sèche à celle des flaques est de 1:2,5. Les flaques occupent en été env. 30% de la surface totale. L'ablation à la face inférieure de la banquise par la chaleur de l'eau fut d'environ 22 cm (Juillet à août/septembre).On décrit les méthodes de mesure du bilan de masse et leur précision. On calcule ce bilan de chaleur à la surface au moment du maximum d'ablation et on en donne les composantes suivantes pour les sommes journalières moyennes en cal/cm²: bilan radiatif de courte longueur d'onde +142, bilan radiatif de grande longueur d'onde –8, flux de convection +9, évaporation –11. L'ablation superficielle moyenne est de 0,8 cm par jour dont 90% résulte de l'absorption du rayonnement à courte longueur d'onde.Le 62% seulement de l'apport de chaleur est transformé à la surface de la glace; le 38% pénètre en profondeur et sert surtout à accroître le volume du mélange salin. A une profondeur de 40 à 150 cm le coefficient d'exctinction pour le rayonnement court est de 0,015 cm^–1, plus faible que dans le glacier terrestre.La quantité de chaleur accumulée en été sert de réserve pendant la période froide pour élever la température de la glace et pour augmenter le volume de la solution saline. Du début de celle-ci jusqu'au minimum des températures en mars, une couche de 3 m d'épaisseur perd 3000 cal/cm² en chaleur latente et 1700 cal/cm² par chute de température. Il est possible d'estimer le bilan total de chaleur des surfaces de la glace à l'aide des variations observées de masse et de température. Pedant la période de mai à août, la surface de la glace reçoit 8,3 kcal/cm², tandis qu'elle cède à l'air 12,8 kcal/cm² de septembre à avril. Les résultats obtenus diffèrent de ceux deYakovlev dans les quantités de l'évaporation et de la réserve calorifique de la glace. Discussion au sujet de la chaleur spécifique de la glace de banquise.

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With 12 Figures

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Contribution No. 51, Department of Meteorology and Climatology, University of Washington.

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The field work was carried out while on leave from the Zentralanstalt für Meteorologie und Geodynamik, Wien.     

Development of a new sea ice growth and lead parameterization

A thermodynamic sea ice model that has been numerically structured to take time steps on the order of a week has been shown to be sensitive to time step size. This sensitivity was caused by the extrapolation of initial ice growth rates over the long time step. A new parameterization of new sea ice growth on open ocean and in leads that can be used over a large range of time step sizes (at least from 0.3 to 12 days) is described here. In this parameterization new sea ice growth is computed as a power law function of the initial energy deficit in the ocean. This power law takes into account the rapid reduction of the ice growth rate as the sea ice gets thicker, and therefore reduces sensitivity to time step size. Tests of this parameterization show that this method does a good job of simulating the rate of new ice growth when compared to data from Mawson, Antarctica, and is relatively insensitive to the length of the time step.     

Simultaneous winter sea‐ice and atmospheric circulation anomaly patterns

Abstract

This study looks at simultaneous changes in atmospheric circulation and extremes in sea‐ice cover during winter. Thirty‐six years of ice‐cover data and 100‐kPa height and 50–100‐kPa thickness data are used. For the entire Arctic, the study found a general weakening of the Aleutian and Icelandic lows for heavy (i.e. severe) compared with light sea‐ice conditions suggesting reduced surface heating as a possible cause. The weakening of the two lows would also reduce meridional atmospheric circulation and poleward heat transport into the Arctic. The study also looks at three regions of high sea ice and atmospheric variability: the Bering Sea, the Davis Strait/Labrador Sea and the Greenland Sea. For the Bering Sea, heavy sea‐ice conditions were accompanied by weakening and westward displacement of the Aleutian Low again suggesting reduced surface heating and the formation of a secondary low in the Gulf of Alaska. This change in circulation is consistent with increased cold air advection over the Bering Sea and changes in storm tracks and meridional heat transport found in other studies. For the Davis Strait/Labrador Sea, heavy ice‐cover winters were accompanied by intensification of the Icelandic Low suggesting atmospheric temperature and wind advection and associated changes in ocean currents as the main cause of heavy ice. For the Greenland Sea no statistically significant difference was found. It is felt that this may be due to the important role that ice export through Fram Strait and ocean currents play in determining ice extent in this region.     

A study of arctic sea ice and sea‐level pressure using POP and neural network methods

Abstract

We examine Arctic sea‐ice concentration (SIC) and sea‐level pressure (SLP) data using principal oscillation pattern (POP) and neural network methods. The POP method extracts oscillating patterns from multivariate time series, each pattern being characterized by an oscillation period and a decay time. Predictions can be made for patterns whose decay time is comparable with the period. For both the SIC and SLP, however, the decay times are much shorter than the oscillation periods, and therefore the forcast skill is poor. A neural network is a model of the learning behaviour of a living neural system. Presented with training data, a neural network can learn the linear or non‐linear rules embedded in the data. We trained neural networks with sea‐ice and sea‐level pressure data, and estimated the forecast skill using a cross‐validation technique. The neural networks did not exhibit forecast skill significantly better than that of persistence. We contrast the Arctic situation with previous studies in which POP and neural networks were successfully used to forecast El Niño at lead times up to 6 months. Reasons for the lack of skill in both methods are discussed.     

Sensitivity to prescribed changes in sea surface temperature and sea ice in doubled carbon dioxide experiments

Time sclice experiments are performed with the atmospheric GCM ARPEGE, developed at Météo-France, to study the impact to increases in the atmospheric carbon dioxide. This spectral model runs at T42 horizontal resolution with 30 vertical layers including a comprehensive tropospheric and stratospheric resolution and a prognostic parameterization of the ozone mixing ratio. The model is forced in a 5-year control run by climatological SSTs and sea-ice extents in order to obtain an accurate simulation of the present-day climate. Two perturbed runs are performed using SSTs and sea-ice extents for doubled CO₂ concentration, obtained from transient runs performed by two coupled atmospheric-oceanic models run at the Max Planck Institute (MPI) in Hamburg and the Hadley Centre (HC). A global surface temperature warming of 1.6 K is obtained with the MPI SST anomalies and 1.9 K with the HC SST anomalies. The precipitation rate increases by 4.2% (and 4.7%). The features obtained in the stratosphere (a cooling increasing with the altitude and an increase in the ozone mixing ratio) are not sensitive to the oceanic forcing. On the contrary, the anomalies in the troposphere such as a warming increasing with altitude, an acceleration of westerly jets and a raised cloud height, depend on the oceanic forcing imposed in the two perturbed runs. Special attention is given to continental areas where the impact of the oceanic forcing is studied over eight regions around the globe. Regions sensitive to oceanic forcing such as Europe are identified in contrast with areas where the patterns are driven by land-surface physical processes, such as over continental Asia. Finally, the Köppen classification is applied to the climate simulated in the three experiments. Both doubled CO₂ runs show the same predominance of global warming over precipitation changes in the Kbppen analyses.     

Structural classification of dynamometamorphic transformations of first-year sea ice

This paper considers the main features of the structure of dynamometamorphic transformations of first-year ice. The structural classification of these transformations is proposed based on laboratory and natural investigations. It is a logical development of the existing structural classification of first-year ice forming in the Arctic seas without the influence of external forcing on the ice cover.