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1.
A. N. Chetyrbotskii 《Russian Meteorology and Hydrology》2007,32(1):43-49
A model of space-time dynamics of the sea ice cover in which individual ice floes undergo a successive change in size is considered. The formation and melting of ice floes, their aggregation, and the formation of hummocks are taken into account. A parametric model identification is done based on a sample of ice cover area and thickness distribution in the Japan Sea. 相似文献
2.
The optimized (all iterative procedures are excluded) local one-dimensional thermody-namic model of the formation and melting of ice is proposed. The numerical computation of ice cover evolution in the Kerch Strait under the influence of thermodynamic factors for the period of 5 months is carried out for the real conditions of winter of 2011/12. Thec results agree well with the available obser-vational data on the timing of ice formation and on ice thickness in the southern part of the Sea of Azov and in the Taman Bay. In combination with the full three-dimensional hydrodynamic model and taking into account diurnal variations in external factors, the model simulates the spatial distribution of ice cover formation. 相似文献
3.
Abstract The sensitivity of the annual cycle of ice cover in Baffin Bay to short‐wave radiation is investigated. The Princeton Ocean Model (POM) is used and is coupled with a multi‐category, dynamic‐thermodynamic sea‐ice model in which the surface energy balance governs the growth rates of ice of varying thickness. During spring and summer the short‐wave radiation flux dominates other surface heat fluxes and thus has the greatest effect on the ice melt. The sensitivity of model results to short‐wave radiation is tested using several, commonly used, shortwave parameterizations under climatological, as well as short‐term, atmospheric forcing. The focus of this paper is short‐term and annual variability. It is shown that simulated ice cover is sensitive to the short‐wave radiation formulation during the melting phase. For the Baffin Bay simulation, the differences in the resulting ice area and volume, integrated from May to November, can be as large as 45% and 70%, respectively. The parameterization of the effect of cloud cover on the short‐wave radiation can result in the sea‐ice area and volume changes reaching 20% and 30%, respectively. The variation of the cloud amount represents cloud data error, and has a relatively small effect (less then ±4%) on the simulated ice conditions. This is due to the fact that the effect of cloud cover on the short‐wave radiation flux is largely compensated for by its effect on the net near‐surface long‐wave radiation flux. 相似文献
4.
A. N. Chetyrbotskii 《Russian Meteorology and Hydrology》2007,32(5):313-319
Results of large-scale mathematical modeling of sea ice cover evolution are analyzed. Special attention is given to formalization of the thermal effect of the atmosphere on ice cover evolution. A model of sea ice cover evolution is developed in which thermal effects of the environment on ice cover and aggregation, fragmentation, and hummocking of ice are taken into account. The model adequacy is estimated by sample distribution of area and thickness of ice cover in the Sea of Japan. 相似文献
5.
The natural low frequency variability of the sea-ice thickness in the Arctic is investigated based on a 10 000 years simulation
with a one-dimensional thermodynamic sea-ice model forced by random perturbations of the air surface temperature and solar
radiation. The simulation results suggest that atmospheric random perturbations are integrated by the sea-ice. Moreover those
perturbations occurring at the onset of ice melting force the largest ice thickness anomalies, which are successively amplified
in summer by the albedo feedback and damped in winter by the feedback of the heat conduction through the ice. They also result
in a global shift of the melting season which, in the mean annual cycle, leads to earlier melting as compared to the mean
climatological cycle. The power spectrum of the ice anomalies suggests that the thickness of the perennial ice should vary
preferentially on a time scale of approximately 20 years. The shape of the spectrum is consistent with that of a first order
Markov process in which the characteristic time scale of the ice fluctuations would be the relaxation time scale associated
with the linear feedback. The equivalent Markov model is constructed by linearizing the ice growth rate anomaly equations
and allows us to derive an analytical expression of the feedback and of the forcing of the anomalies. The characteristic time
scale depends explicitly on those model parameters involved in the atmosphere-ice interaction but also on the mean seasonal
characteristics of the forcing and of the ice thickness.
Received: 18 August 1999 / Accepted: 10 May 2000 相似文献
6.
The performance of a snow cover model in capturing the ablation on the Greenland ice sheet is evaluated. This model allows an explicit calculation of the formation of melt water, of the fraction of melt water which re-freezes, and of runoff in the ablation region. The input climate variables to the snowpack model come from two climate models. While the higher resolution general circulation model (ECHAM 4), is closest to observations in its estimate of accumulation, it fails to give accurate results in its predictions of runoff, primarily in the southern half of the ice sheet. The two-dimensional low-resolution climate model (MIT 2D LO) produces estimates of runoff from the Greenland ice sheet within the range of uncertainty of the Inter governmental Panel on Climate Change (IPCC1) 1995 estimates. Both models reproduce some of the characteristics of the extent of the wet snow zone observed with satellite remote sensing; the MIT model is closer to observations in terms of areal extent and intensity of the melting in the southern half of the ice-sheet in July and August while the ECHAM model reproduces melting in the northern half of the ice sheet well. Changes in runoff from Greenland and Antarctica are often cited as one of the major concerns linked to anthropogenic changes in climate. Because it is based on physical principles and relies on the surface energy balance as input, the snow cover model can respond to the current climatic forcing as well as to future changes in climate on the century time scale without the limitations inherent in empirical parametrizations. For a reference climate scenario similar to the IPCC's IS92a, the model projects that the Greenland ice sheet does not contribute significantly to changes in the level of the ocean over the twenty-first century. Increases in accumulation over the central portion of the ice sheet offset most of the increase in melting and runoff, which takes place along the margins of the ice sheet. The range of uncertainty in the predictions of sea-level rise is estimated by repeating the calculation with the MIT model for seven climate change scenarios. The range is –0.5 to 1.7 cm. 相似文献
7.
M. V. Bukharov 《Russian Meteorology and Hydrology》2013,38(1):35-43
Analyzed is the interrelation between the properties of the sea ice, its scattering index at the frequencies of 23 and 31 GHz, and the brightness temperature computed from the multispectral measurements with the AMSU radiometer. Within the frameworks of the simplified model representations, the quantitative estimates are obtained of the influence of the ice thickness, ice concentration, and presence of inhomogeneities in the emitting layer and snow cover on the ice surface on the ice scattering index values. It is demonstrated that the scattering on the dislocations formed near the surface of ice at its bend and compression can be the main reason for the rapid change in the scattering index of one-year and old ice observed in different seasons. The results of the analysis corroborated the validity of applying the scattering index for the revelation of the areas of deformation and hummocking of sea ice, as well as for the estimation of the age and thickness of thin and young ice. 相似文献
8.
国家气候中心气候系统模式BCC_CSM2.0最新耦合了美国Los Alamos国家实验室发展的海冰模式CICE5.0,为试验模式中与反照率相关参数的敏感性及其对模拟结果的影响,提高模式对北极海冰的模拟能力,选取海冰模式中3个主要参数进行了敏感性试验。利用以BCC_CSM2.0耦合框架为基础建立的海冰-海洋耦合模式,选取CORE资料为大气强迫场开展试验,试验的3个参数分别为冰/雪表面反射率、雪粒半径和雪粒半径参考温度。结果表明,参数取值的不同对北极海冰的模拟有显著的影响,优化后的取值组合极大提高了模式的模拟能力,主要表现在:（1）改善了对北极冬季海冰厚度的模拟,海冰厚度增大,与观测资料更为吻合;（2）显著提高了对北极夏季海冰密集度的模拟能力,从而模拟的北极海冰范围年际循环与观测更为一致。参数取值的优化改进了模式对海冰反照率的模拟,进而影响了冰面短波辐射的吸收和海冰表层的融化,最终提高了模式对海冰密集度和厚度的模拟效果。 相似文献
9.
Relationships between the ice cover thickness alimentation and negative temperatures sums are defined for several ice profiles in the Votkinsk reservoir. Possibility of their using for the ice cover thickness forecasting is considered. Criteria of the acceptable errors of the ice cover forecasts and computations are studied. A new way of their improvement is proposed. 相似文献
10.
Inherent sea ice predictability in the rapidly changing Arctic environment of the Community Climate System Model, version 3 总被引：2，自引：1，他引：1
Seasonal predictions of Arctic sea ice have typically been based on statistical regression models or on results from ensemble ice model forecasts driven by historical atmospheric forcing. However, in the rapidly changing Arctic environment, the predictability characteristics of summer ice cover could undergo important transformations. Here global coupled climate model simulations are used to assess the inherent predictability of Arctic sea ice conditions on seasonal to interannual timescales within the Community Climate System Model, version 3. The role of preconditioning of the ice cover versus intrinsic variations in determining sea ice conditions is examined using ensemble experiments initialized in January with identical ice?Cocean?Cterrestrial conditions. Assessing the divergence among the ensemble members reveals that sea ice area exhibits potential predictability during the first summer and for winter conditions after a year. The ice area exhibits little potential predictability during the spring transition season. Comparing experiments initialized with different mean ice conditions indicates that ice area in a thicker sea ice regime generally exhibits higher potential predictability for a longer period of time. In a thinner sea ice regime, winter ice conditions provide little ice area predictive capability after approximately 1?year. In all regimes, ice thickness has high potential predictability for at least 2?years. 相似文献
11.
Submarine and satellite observations show that the Arctic Ocean ice cover has undergone a large thickness reduction and a decrease in the areal extent during the last decades. Here the response of the Arctic Ocean ice cover to changes in the poleward atmospheric energy transport, F wall, is investigated using coupled atmosphere-ice-ocean column models. Two models with highly different complexity are used in order to illustrate the importance of different internal processes and the results highlight the dramatic effects of the negative ice thickness—ice volume export feedback and the positive surface albedo feedback. The steady state ice thickness as a function of F wall is determined for various model setups and defines what we call ice thickness response curves. When a variable surface albedo and snow precipitation is included, a complex response curve appears with two distinct regimes: a perennial ice cover regime with a fairly linear response and a less responsive seasonal ice cover regime. The two regimes are separated by a steep transition associated with surface albedo feedback. The associated hysteresis is however small, indicating that the Arctic climate system does not have an irreversible tipping point behaviour related to the surface albedo feedback. The results are discussed in the context of the recent reduction of the Arctic sea ice cover. A new mechanism related to regional and temporal variations of the ice divergence within the Arctic Ocean is presented as an explanation for the observed regional variation of the ice thickness reduction. Our results further suggest that the recent reduction in areal ice extent and loss of multiyear ice is related to the albedo dependent transition between seasonal and perennial ice i.e. large areas of the Arctic Ocean that has previously been dominated by multiyear ice might have been pushed below a critical mean ice thickness, corresponding to the above mentioned transition, and into a state dominated by seasonal ice. 相似文献
12.
Abstract This study reports on the implementation of an interactive mixed‐layer/thermodynamic‐ice lake model coupled with the Canadian Regional Climate Model (CRCM). For this application the CRCM, which uses a grid mesh of 45 km on a polar stereographic projection, 10 vertical levels, and a timestep of 15 min, is nested with the second generation Canadian General Circulation Model (GCM) simulated output. A numerical simulation of the climate of eastern North America, including the Laurentian Great Lakes, is then performed in order to evaluate the coupled model. The lakes are represented by a “mixed layer” model to simulate the evolution of the surface water temperature, and a thermodynamic ice model to simulate evolution of the ice cover. The mixed‐layer depth is allowed to vary spatially. Lake‐ice leads are parametrized as a function of ice thickness based on observations. Results from a 5‐year integration show that the coupled CRCM/lake model is capable of simulating the seasonal evolution of surface temperature and ice cover in the Great Lakes. When compared with lake climatology, the simulated mean surface water temperature agrees within 0.12°C on average. The seasonal evolution of the lake‐ice cover is realistic but the model tends to underestimate the monthly mean ice concentration on average. The simulated winter lake‐induced precipitation is also shown, and snow accumulation patterns on downwind shores of the lakes are found to be realistic when compared with observations. 相似文献
13.
In this paper, results of numerical experiments based on the one-dimensional thermodynamic model of hummock formations evolution, which has been developed by the authors, are analysed. This model has been used for computation of relative rates of freezing and melting of hummocks in typical conditions of the northeastern shelf of Sakhalin Island; then obtained values were compared with the plain sea ice cover parameters simulated by using climate and actual meteorological data. It is shown that obtained results well comply with observational data collected during expeditions in this region. 相似文献
14.
Abstract The steady, coupled ice‐ocean circulation model of Willmott and Mysak (1989) for a meridional channel is applied to the Labrador Sea for the winter season. The model consists of a thermodynamic reduced‐gravity ocean combined with a variable thickness ice cover that is in thermal equilibrium. Upon specifying the forcing fields of surface air temperature, wind stress and water temperature along the open southern boundary, the winter climatological ice‐edge position, ice thickness, ocean circulation and temperature fields are determined in the channel domain. The sensitivity of the results to the various model parameters is examined. In particular, the optimum heat exchange coefficients for the interfaces of air‐water, ice‐water and air‐ice are found. The model ice‐edge position compares favourably with the 50% winter climatological ice concentration isoline obtained from an analysis of 32 years (1953–84) of sea‐ice concentration data. The simulations of the ocean temperature and ice thickness are also quite realistic according to the observed records available. The model is also applied to two specific winters (1981 and 1983) during which anomalous sea‐ice and weather conditions prevailed in the Labrador Sea. 相似文献
15.
The response of the hydrological cycle to climate variability and change is a critical open question, where model reliability is still unsatisfactory, yet upon which past climate history can shed some light. Sea ice is a key player in the climate system and in the hydrological cycle, due to its strong albedo effect and its insulating effect on local evaporation and air-sea heat flux. Using an atmospheric general circulation model with specified sea surface temperature and sea-ice distribution, the role of sea ice in the hydrological cycle is investigated under last glacial maximum (LGM) and present day conditions, and by studying its contribution to the “temperature-precipitation feedback”. By conducting a set of sensitivity experiments in which the albedo and thickness of the sea ice are varied, the various effects of sea ice in the hydrological cycle are isolated. It is demonstrated that for a cold LGM like state, a warmer climate (as a result of reduced sea-ice cover) leads to an increase in snow precipitation over the ice sheets. The insulating effect of the sea ice on the hydrological cycle is found to be larger than the albedo effect. These two effects interact in a nonlinear way and their total effect is not equal to summing their separate contribution. 相似文献
16.
M. V. Bukharov N. S. Mironova I. G. Ushcheko A. M. Kotilevskaya V. M. Losev V. M. Bukharov 《Russian Meteorology and Hydrology》2014,39(4):245-253
Considered are simplified model concepts allowing the use of the AMSU microwave radiometer measurement data and the maps of scattering index (SI) compiled by them for estimating the variability of the thickness of thin and young ice as well as for obtaining principally new satellite information about the areas of the possible hummocking of ice cover. Demonstrated is the essential influence of deep cyclones on the ice thickness reduction due to the ice thawing from below in the areas where waves are driven under the ice from the warmer, not frozen part of the water area. Carried out is a comparative analysis of sea ice properties identified from SI maps and the traditional maps of ice condition analysis. Noted is a possibility of the useful application of all-weather SI maps for monitoring sea ice properties in the areas of their rapid variability formed during the periods of a deep cyclone passage. 相似文献
17.
The interannual variation of the Arctic Ocean ice thickness during the period 1954–1990 is investigated by using a coupled ocean-ice-atmosphere column model. The model is forced by poleward energy flux in the atmosphere from NCEP/NCAR reanalysis data, ice export from satellite observations, cloudiness, and precipitation observed at the Russian North Pole drift stations. During the period 1977–1986 the model ice thickness decreased from 3.2 m to 2.0 m. The decrease is mainly caused by extra melting due to larger poleward energy flux in summer, and reduced ice growth in winter as a result of both increased cloudiness and energy flux. Precipitation and ice export are of less importance. A sensitivity study shows that the NCEP/NCAR data is accurate enough with respect to stochastic errors to ensure that the thinning is not caused by forcing errors. It is also shown that the poleward energy flux during summer is the dominant factor for regulating the ice thickness. The column model gives different results compared to other model studies using 2D ice models, especially towards the end of the period. Possible reasons for this disparity are discussed. 相似文献
18.
利用常规气象资料建立的导线覆冰模型 总被引：1，自引：1，他引：0
利用2001-2009年冬季四川省二郎山观冰站的覆冰资料和气象资料,在明确影响导线覆冰因子及建立覆冰模型理论框架的基础上,分析了覆冰厚度与若干气象因子的联系,结果发现覆冰增长与水汽压、风速等单一气象指标之间的相关并不理想;尝试用若干气象指标综合咸水汽输送量指标,该指标与覆冰增长率有较显著的相关。在此基础上建立了一个以风速、温度、水汽压等常规气象观测要素为参数的导线覆冰模型,将综合覆冰拟合的冰厚与实测冰厚值进行比较,拟合结果较好地模拟了实际覆冰,达到工程应用的目的。 相似文献
19.
On modelling the seasonal thermodynamic cycle of sea ice in studies of climatic change 总被引：1，自引：0，他引：1
Albert J. Semtner Jr. 《Climatic change》1984,6(1):27-37
Recent work in modelling climatic changes due to increased atmospheric CO2 has shown the maximum change to occur in the polar regions as a result of seasonal reductions in sea ice coverage. Typically, sea ice thermodynamics is modelled in a very simple way, whereby the storage of both sensible and latent heat within the ice is ignored, and the effects of snow cover on conductivity and on surface albedo and of oceanic heat flux on bottom ablation may also be neglected. This paper considers whether omission of these processes is justified within the context of quantitatively determining regional climatic changes. A related question, whether omission of ice dynamics can be justified, is not considered.Relatively complete one-dimensional models of sea-ice thermodynamics have previously been developed and tested for a variety of environmental conditions by Maykut and Untersteiner (1969, 1971) and by Semtner (1976). A simpler model which neglects the storage of sensible and latent heat is described in the Appendix to Semtner (1976). In that model, the errors in annual-mean ice thickness which would arise from neglect of heat storage can be compensated by increases in albedo and in conductivity. Here we examine the seasonal cycle of ice thickness predicted by such a model and find significant errors in phase (one month lead) and in amplitude (50% overestimate). The amplitude errors are enhanced as snowfall and oceanic heat flux diminish (or are neglected). This suggests that substantial errors may occur in climate simulations which use very simple formulations of sea ice thermodynamics, whereby early and excessive melting exaggerates the seasonal disappearance of sea ice.To illustrate the above point, two models are configured to examine the local response of Arctic sea ice to a quadrupling of atmospheric CO2. The first model neglects a number of physical processes and mimics the behavior of sea ice found in Manabe and Stouffer (1980), both for present and enhanced levels of CO2. The more complete second model gives a better simulation of Arctic ice for the present level of CO2 and shows a reduced response to CO2 quadrupling relative to that in Manabe and Stouffer (1980). In particular, the change in surface temperature is cut by a factor of two. In view of this result, a more complete treatment of sea ice thermodynamics would seem warranted in further studies of climate change. Only a minor computational increase is required.A portion of this study is supported by the U.S. Department of Energy as a part of its Carbon Dioxide Research Program.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
20.
Variability of Northeast China river break-up date 总被引：5，自引：0，他引：5
This paper investigates the variability of the break-up dates of the rivers in Northeast China from their icebound states for the period of 1957–2005 and explores some potential explanatory mechanisms. Results show that the break-up of the two major rivers(the Heilongjiang River and Songhuajiang River) was about four days earlier,and their freeze-up was about 4–7 days delayed,during 1989–2005 as compared to 1971–1987.This interdecadal variation is evidently associated with the warming trend over the past 50... 相似文献