Evaluation of Arctic Sea Ice Drift and its Relationship with Near-surface Wind and Ocean Current in Nine CMIP6 Models from China

The simulated Arctic sea ice drift and its relationship with the near-surface wind and surface ocean current during 1979-2014 in nine models from China that participated in the sixth phase of the Coupled Model Intercomparison Project(CMIP6)are examined by comparison with observational and reanalysis datasets.Most of the models reasonably represent the Beaufort Gyre(BG)and Transpolar Drift Stream(TDS)in the spatial patterns of their long-term mean sea ice drift,while the detailed location,extent,and strength of the BG and TDS vary among the models.About two-thirds of the models agree with the observation/reanalysis in the sense that the sea ice drift pattern is consistent with the near-surface wind pattern.About the same proportion of models shows that the sea ice drift pattern is consistent with the surface ocean current pattern.In the observation/reanalysis,however,the sea ice drift pattern does not match well with the surface ocean current pattern.All nine models missed the observational widespread sea ice drift speed acceleration across the Arctic.For the Arctic basin-wide spatial average,five of the nine models overestimate the Arctic long-term(1979-2014)mean sea ice drift speed in all months.Only FGOALS-g3 captures a significant sea ice drift speed increase from 1979 to 2014 both in spring and autumn.The increases are weaker than those in the observation.This evaluation helps assess the performance of the Arctic sea ice drift simulations in these CMIP6 models from China.     

Satellite Monitoring of Sea Ice Cover and Water Parameters for the Caspian Sea

A number of technologies have been developed in the Planeta Research Center for Space Hydrometeorology to provide the satellite monitoring of sea ice cover and water parameters for the Caspian Sea. These technologies produce maps of sea ice, sea ice drift, tracking of near-surface water fluxes, automated classification of ice and water objects, surface wind, and sea surface temperature. Satellite-based products are used for operational hydrometeorology and climate studies of the Caspian Sea environment. A specialized web service for the preparation and comprehensive analysis of satellite data on hydrometeorological and ice conditions in the Caspian Sea was developed to provide information on ice cover characteristics, surface wind, and sea surface temperature.     

Influence of Atlantic Water on the Sea Ice Cover in the Western Arctic in Winter

The results of temperature and salinity measurements in the upper 1000-mlayer of the Nansen Basin in the Arctic Ocean made from the North Pole-35 drifting station in winter of 2007/2008 are analyzed. The uniqueness of the dataset processed is defined by the station drift path in the Nansen Basin and by the time of the drift which immediately followed the record decline of Arctic sea ice in September 2007. It is found that the maximum heat flux from the ocean to the ice cover equal to more than 90 W/m² was observed in the area of Atlantic water in flow between Spitsbergen and Franz Josef Land. It was caused by the drift velocity increase and by the corresponding deepening of the Ekman boundary layer. No significant changes (as compared to climate normals) in the influence of ocean heat on the ice cover in the eastern Nansen Basin in winter were registered.     

Thinner Sea Ice Contribution to the Remarkable Polynya Formation North of Greenland in August 2018

In August 2018, a remarkable polynya was observed off the north coast of Greenland, a perennial ice zone where thick sea ice cover persists. In order to investigate the formation process of this polynya, satellite observations, a coupled iceocean model, ocean profiling data, and atmosphere reanalysis data were applied. We found that the thinnest sea ice cover in August since 1978(mean value of 1.1 m, compared to the average value of 2.8 m during 1978-2017) and the modest southerly wind caused by a positive North Atlantic Oscillation(mean value of 0.82, compared to the climatological value of-0.02) were responsible for the formation and maintenance of this polynya. The opening mechanism of this polynya differs from the one formed in February 2018 in the same area caused by persistent anomalously high wind. Sea ice drift patterns have become more responsive to the atmospheric forcing due to thinning of sea ice cover in this region.     

渤海海冰数值模式的研究进展

根据渤海海冰冰情,从热力和动力两个方面综述了渤海海冰数值模式的研究进展。从热力参数方案和气候特点上,展望新一代渤海中小尺度短期海冰热力模式;从海冰动力模式中3种常用数值方法的主要特点和实际应用情况上,论述SPH(Smoothed Particle Hydrodynamics)方法在渤海海冰短期预报的发展前景。在此基础上,结合海洋气象的发展,讨论海冰短期预报的关键技术。将海冰数值预报模式与传统的中长期海冰统计预报有机地结合起来将是渤海海冰模式未来的发展方向。     

一个热动力海冰模式的改进与实验

影响海冰变化的物理因素中热力和动力部分是同等重要的，但多数热动力海冰模式的热力部分考虑得较为简单。针对Hibler热动力海冰模式的不足，以1个3层热力模式为基础改进了其热力部分。比较了原模式中的零层热力模式和用于改进的3层热力模式；并应用改进前后的两种热动力模式对1983年的北极海冰进行了模拟。模拟结果表明，海冰厚度比原模式厚，季节变化减弱，海冰密集度与观测资料更为符合。     

定量计算渤海海冰参数的遥感方法

利用NOAA及FY-1卫星监测渤海海冰的亮度温度、反照率及其与海水的差异建立了冰、水识别判据,并根据海冰反照率与冰厚的关系,对海冰进行分类。在解决了混合象元内含冰信息提取的基础上,计算了海冰覆盖度和面积等参数。     

Generation and atmospheric heat exchange of coastal polynyas in the Weddell Sea

The forcing mechanisms for Antarctic coastal polynyas and the thermodynamic effects of existing polynyas are studied by means of an air-sea-ice interaction experiment in the Weddell Sea in October and November 1986.Coastal polynyas develop in close relationship to the ice motion and form most rapidly with offshore ice motion. Narrow polynyas occur frequently on the lee side of headlands and with strong curvature of the coastline. From the momentum balance of drifting sea ice, a forcing diagram is constructed, which relates ice motion to the surface-layer wind vector v _z and to the geostrophic ocean current vector c _g . In agreement with the data, wind forcing dominates when the wind speed at a height of 3 m exceeds the geostrophic current velocity by a factor of at least 33. This condition within the ocean regime of the Antarctic coastal current usually is fulfilled for wind speeds above 5 m/s at a height of 3 m.Based on a nonlinear parameter estimation technique, optimum parameters for free ice drift are calculated. Including a drift dependent geostrophic current in the ice/water drag yields a maximum of explained variance (91%) of ice velocity.The turbulent heat exchange between sea ice and polynya surfaces is derived from surface-layer wind and temperature data, from temperature changes of the air mass along its trajectory and from an application of the resistance laws for the atmospheric PBL. The turbulent heat flux averaged over all randomly distributed observations in coastal polynyas is 143 W/m². This value is significantly different over pack ice and shelf ice surfaces, where downward fluxes prevail. The large variances of turbulent fluxes can be explained by variable wind speeds and air temperatures. The heat fluxes are also affected by cloud feedback processes and vary in time due to the formation of new ice at the polynya surface.Maximum turbulent fluxes of more than 400 W/m² result from strong winds and low air temperatures. The heat exchange is similarly intense in a narrow zone close to the ice front, when under weak wind conditions, a local circulation develops and cold air associated with strong surface inversions over the shelf ice is heated above the open water.     

北极海冰变化对新疆冬季气温的影响研究

利用1961年12月—2022年2月新疆冬季气温、北极海冰等资料,探讨北极海冰变化影响新疆冬季气温的物理模态、影响机制。结果表明,北极海冰的变化与新疆大部冬季气温呈正相关,北极海冰变化通过改变北半球大气高低空配置进而影响新疆冬季气温。另外,不同海区的海冰变化对新疆冬季气温的影响有显著区别：格陵兰海—丹麦海峡、拉普捷夫海—东西伯利亚海海冰异常偏多时,新疆大部冬季气温偏高。巴伦支海—喀拉海、鄂霍次克海—白令海峡、哈德孙湾—戴维斯海峡海冰异常偏多时,新疆大部冬季气温偏低。     

Record Low Sea-Ice Concentration in the Central Arctic during Summer 2010

The Arctic sea-ice extent has shown a declining trend over the past 30 years. Ice coverage reached historic minima in 2007 and again in 2012. This trend has recently been assessed to be unique over at least the last 1450 years. In the summer of 2010, a very low sea-ice concentration(SIC) appeared at high Arctic latitudes—even lower than that of surrounding pack ice at lower latitudes. This striking low ice concentration—referred to here as a record low ice concentration in the central Arctic(CARLIC)—is unique in our analysis period of 2003–15, and has not been previously reported in the literature. The CARLIC was not the result of ice melt, because sea ice was still quite thick based on in-situ ice thickness measurements.Instead, divergent ice drift appears to have been responsible for the CARLIC. A high correlation between SIC and wind stress curl suggests that the sea ice drift during the summer of 2010 responded strongly to the regional wind forcing. The drift trajectories of ice buoys exhibited a transpolar drift in the Atlantic sector and an eastward drift in the Pacific sector,which appeared to benefit the CARLIC in 2010. Under these conditions, more solar energy can penetrate into the open water,increasing melt through increased heat flux to the ocean. We speculate that this divergence of sea ice could occur more often in the coming decades, and impact on hemispheric SIC and feed back to the climate.     

Stratospheric Ozone-induced Cloud Radiative Effects on Antarctic Sea Ice

Recent studies demonstrate that the Antarctic Ozone Hole has important influences on Antarctic sea ice. While most of these works have focused on effects associated with atmospheric and oceanic dynamic processes caused by stratospheric ozone changes, here we show that stratospheric ozone-induced cloud radiative effects also play important roles in causing changes in Antarctic sea ice. Our simulations demonstrate that the recovery of the Antarctic Ozone Hole causes decreases in clouds over Southe...     

The Impact of Sediment-Laden Snow and Sea Ice in the Arctic on Climate

Sea ice formed over shallow Arctic shelves often entrains sediments resuspended from the sea floor. Some of this sediment-laden ice advects offshore into the Transpolar Drift Stream and the Beaufort Gyre of the Arctic Basin. Through the processes of seasonal melting at the top surface, and the freezing of clean ice on the bottom surface, these sediments tend, over time, to concentrate at the top of the ice where they can affect the surface albedo, and thus the absorbed solar radiation, when the ice is snow free. Similarly, wind-blown dust can reduce the albedo of snow. The question that is posed by this study is what is the impact of these sediments on the seasonal variation of sea ice, and how does it then affect climate? Experiments were conducted with a coupled energy balance climate-thermodynamic sea ice model to examine the impact of including sediments in the sea ice alone and in the sea ice and overlying snow. The focus of these experiments was the impact of the radiative and not the thermal properties of the sediments. The results suggest that if sea ice contains a significant amount of sediments which are covered by clean snow, there is only a small impact on the climate system. However, if the snow also contains significant sediments the impact on sea ice thickness and surface air temperature is much more significant.     

冬季北极海冰运动主模态的构成及其与海平面气压变化的关系

利用国际北极浮冰运动观测资料（IABP）（1979-1998）以及NCEP／NCAR月平均海平面气压再分析资料（1960-2002）,通过求解海冰运动异常的复斜方差矩阵,研究了冬季北极海冰运动主模态构成及其与海平面气压变化的关系。冬季海冰运动主模态是由两个海冰运动优势模态的一个线性组合构成,与这两个运动优势模态有直接关系的海平面气压变化主要发生在北极海盆及其边缘海区。尽管北极涛动（北大西洋涛动）通过影响海平面气压进而影响北极海冰运动,但是,北极涛动（北大西洋涛动）并不是决定海冰运动主模态的关键性因素。     

The Response of Arctic Sea Ice to Global Change

The sea ice-covered polar oceans have received wider attention recently for two reasons. Firstly, the global conveyor belt circulation of the ocean is believed to be forced in the North and South Atlantic through deep water formation, which to a large degree is controlled by the variations of the sea ice margin and especially by the sea ice export to lower latitudes. Secondly, CO₂ response experiments with coupled climate models show an enhanced warming in polar regions for increased concentrations of atmospheric greenhouse gases. Whether this large response in high latitudes is due to real physical feedback processes or to unrealistic simplifications of the sea ice model component remains to be determined. Coupled climate models generally use thermodynamic sea ice models or sea ice models with oversimplified dynamics schemes. Realistic dynamic-thermodynamic sea ice models are presently implemented only at a few modeling centers. Sensitivity experiments with thermodynamic and dynamic-thermodynamic sea ice models show that the more sophisticated models are less sensitive to perturbations of the atmospheric and oceanic boundary conditions. Because of the importance of the role of sea ice in mediating between atmosphere and ocean an improved representation of sea ice in global climate models is required. This paper discusses present sea ice modeling as well as the sensitivity of the sea ice cover to changes in the atmospheric boundary conditions. These numerical experiments indicate that the sea ice follows a smooth response function: sea ice thickness and export change by 2% of the mean value per 1 Wm^-2 change of the radiative forcing.     

Sea ice in the Barents Sea: seasonal to interannual variability and climate feedbacks in a global coupled model

Sea ice variability in the Barents Sea and its impact on climate are analyzed using a 465-year control integration of a global coupled atmosphere–ocean–sea ice model. Sensitivity simulations are performed to investigate the response to an isolated sea ice anomaly in the Barents Sea. The interannual variability of sea ice volume in the Barents Sea is mainly determined by variations in sea ice import into Barents Sea from the Central Arctic. This import is primarily driven by the local wind field. Horizontal oceanic heat transport into the Barents Sea is of minor importance for interannual sea ice variations but is important on longer time scales. Events with strong positive sea ice anomalies in the Barents Sea are due to accumulation of sea ice by enhanced sea ice imports and related NAO-like pressure conditions in the years before the event. Sea ice volume and concentration stay above normal in the Barents Sea for about 2 years after an event. This strongly increases the albedo and reduces the ocean heat release to the atmosphere. Consequently, air temperature is much colder than usual in the Barents Sea and surrounding areas. Precipitation is decreased and sea level pressure in the Barents Sea is anomalously high. The large-scale atmospheric response is limited with the main impact being a reduced pressure over Scandinavia in the year after a large ice volume occurs in the Barents Sea. Furthermore, high sea ice volume in the Barents Sea leads to increased sea ice melting and hence reduced surface salinity. Generally, the climate response is smallest in summer and largest in winter and spring.     

一个冰气相互作用数值模拟结果的可能统计解释

基于一个全球海-冰-气耦合模式的数值模拟结果,选取冬季格陵兰海海表面温度(SST)、海冰密集度、海表面感热通量等物理量以及3个相关区域海平面气压分别作经验正交函数展开,取第一模时间系数作相关分析。结果表明,上一年海冰密集度偏大(小)与来年的SST偏低(高)相联系,但二者同期相关性最大。当海气热通量交换变化超前一年时,其与SST相关性最大。模式最低层大气温度与海洋表面热通量之间的同时相关性最大,冬季模式最低层气温偏高(低)与海洋表面失去的感热、潜热通量偏少(多)相联系。气温、比湿都和冰岛低压区及格陵兰海的海平面气压相关性最强,冰岛低压气压偏低(高)与模式最低层气温和比湿偏高(低)相联系。所以,在海-冰-气年际尺度的相互作用中,主要关系是大气环流调整造成大气中云量和低层气温、湿度变化,进而影响海气界面上的通量交换,造成SST的变化。SST变化决定着海冰范围及海冰密集度的变化,但海冰变化时通过相变潜热的释放或吸收反过来对SST变化有较明显影响。     

南极海冰变异对华南后汛期旱涝的影响

应用逐月南极海冰北界资料和南半球海平面气压场资料,研究了南极海冰变异对华南后汛期旱涝的显著影响作用和可能机理,认为：南极总海冰、威德尔海海冰冰长期和罗斯海海冰最大面积的变异对后汛期的作用最为显著。９月罗斯海海冰最大面积变化与次年７～９月西太平洋副高关系密切,副高在海冰与后汛期关系中起重要纽带作用。后汛期旱涝可能是南极海冰变异产生的全球短期气候效应的结果之一     

Computation of extreme ice drift velocities on the northeastern shelf of Sakhalin Island from radar measurements

The technology ofthe method of joint probabilities ofthe tidal and residual (de-tided) components developed to estimate the possible sea level fluctuations [1, 10] and modified to calculate rare extreme total sea current velocities [8], is applied to compute ice drift velocity on the northeastern shelf of Sakhalin Island. The initial data are the hourly series of the drift velocity vector obtained from radar observations at Odoptu coastal station (1986-1996, during the whole ice season) and at the Molikpaq drilling platform (in May in 1999, 2000, 2003, 2005, and 2006). The distribution of the tidal component was determined by the prediction of the corresponding series for 19 years that is possible due to the stability of characteristics of the tidal drift. The distribution of the residual component was estimated by combining all de-tided series for the entire time period. The obtained estimates of total ice drift velocities of rare occurrence are in good agreement with those presented in [8] and can be used for designing facilities for the extraction and transportation of hydrocarbons on the northeastern shelf of Sakhalin Island.     

近年来国外海冰模式发展的回顾

海冰是气候系统中的重要成员，而海冰模式是描述海冰物理过程、模拟和预报海冰演变的有力工具。根据国外发表的文献，对海冰模式从动力学、热力学和厚度分布三个方面的研究进行了回顾，对海冰模拟的研究具有一定的借鉴作用。     

20世纪90年代以来北极海冰减少的热动力分析——基于PIOMAS模式结果

本文利用美国华盛顿大学的PIOMAS海冰模式输出结果,分析了20世纪90年代以来北极海冰减少的动力和热力过程的特征,并探讨了海冰减少与北极大气环流模态之间的关系。结果表明:（1）通过弗拉姆海峡输出的多年冰的厚度自1995年以来有显著减少;（2）海冰的热力过程在20世纪90年代以后特别是21世纪以来是海冰减少的主导因素;（3）大气模态中的北极涛动（AO）和北极偶极子（AD）均对北极海冰的动力输出有影响,各自与海冰输出量的相关关系显著,并且AO和AD的多元线性回归能很好的拟合出海冰输出量的减少。