BCC_CSM对全球海冰面积和厚度模拟及其误差成因分析

本文评估了国家气候中心发展的BCC_CSM模式对全球海冰的模拟能力,结果表明:该气候系统模式能够较好地模拟出全球海冰面积和厚度的时空分布特征,且南半球海冰模拟能力优于北半球。通过对比分析发现:年平均海冰面积模拟误差最大的区域位于鄂霍次克海、白令海和巴伦支海等海区,年平均海冰厚度分布与观测相近,在北半球冬季模拟的厚度偏薄;从海冰季节变化来看,模拟的夏季海冰面积偏低,冬季偏高;从海冰年际变化来看,近60年南北半球海冰面积模拟都比观测偏多,但南半球偏多幅度较小,然而北半球海冰年际变化趋势的模拟却好于南半球。另外,通过对海冰模拟误差成因分析,发现模拟的净辐射能量收入偏低使得海温异常偏冷,是导致北半球冬季海冰模拟偏多的主要原因。     

Change and variability in sea ice during the 2007–2008 Canadian International Polar Year program

In this paper we describe sea ice change and variability during the Canadian International Polar Year (IPY) program and examine several regional and hemispheric causes of this change. In a companion paper (Barber et al., Climate Change 2012) we present an overview of the consequences of this observed change and variability on ecosystem function, climatically relevant gas exchange, habitats of primary and apex predators, and impacts on northern peoples. Sea ice-themed research projects within the fourth IPY were designed to be among the most diverse international science programs. They greatly enhanced the exchange of Inuit knowledge and scientific ideas across nations and disciplines. This interdisciplinary and cultural exchange helped to explain and communicate the impacts of a transition of the Arctic Ocean and ecosystem to a seasonally ice-free state, the commensurate replacement of perennial with annual sea ice types and the causes and consequences of this globally significant metamorphosis. This paper presents a synthesis of scientific sea ice research and traditional knowledge results from Canadian-led IPY projects between 2007 and 2009. In particular, a summary of sea ice trends, basin-wide and regional, is presented in conjunction with Inuit knowledge of sea ice, gathered from communities in northern Canada. We focus on the recent observed changes in sea ice and discuss some of the causes of this change including atmospheric and oceanic forcing of both dynamic and thermodynamic forcing on the ice. Pertinent results include: 1) In the Amundsen Gulf, at the western end of the Northwest Passage, open water persists longer than normal and winter sea ice is thinner and more mobile. 2) Large areas of summer sea ice are becoming heavily decayed during summer and can be broken up by long-period waves being generated in the now extensive open water areas of the Chukchi Sea. 3) Cyclones play an important role in flaw leads??regions of open water between pack ice and land-fast ice. They delay the formation of new ice and the growth of multi-year ice. 4) Feedbacks involving the increased period of open water, long-period wave generation, increased open-ocean roughness, and the precipitation of autumn snow are all partially responsible for the observed reduction in multiyear sea ice. 5) The atmosphere is observed as remaining generally stable throughout the winter, preventing vertical entrainment of moisture above the surface.     

GMS实时资料遥感海冰的研究

利用１９９５年１，２月ＧＭＳ－４的红外亮温和可见光反照率资料，以辽东湾海冰为对象，根据冰水物理特性的差异，建立了冰水识别的判据和冰厚与亮温、反照率的对应关系，反演出冰厚和冰密集度数字分布。结果表明，冰水识别的准确率为８４．８％，冰厚反演误差为３．８ｃｍ，密集度反演误差为２２％。     

Methodology of evaluation of forecasts of the reservoir ice cover thickness (the Votkinsk reservoir case study)

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.     

On the Arctic Ocean ice thickness response to changes in the external forcing

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.     

SIMULATION ON CLIMATIC VARIATION OF ARCTIC SEA ICE THROUGH AN ICE-OCEAN COUPLED MODEL*

An ocean model developed by the Institute of Marine Research and the University of Bergen in Norway (BOM) and a state-of-the-art sea ice model developed by NCAR (CSIM4) are coupled, Considering influences of 9 major rivers,forced by the NCEP reanalysis atmospheric fields and the Levitus surface salinity,the Arctic sea ice climatic variation from January 1949 to December.1999 was simulated through the coupled model.The comparison of simulated results and observations shows that:(1)the long-term ice concentration variation tendencies are in consistent with the observations in the divisional ocean regions;(2)simulated ice thickness horizontal distribution is reasonable.Simulated ice thickness has a decreasing tendency in the central Arctic,which agrees with the submarine observations.Simulated annually maximum ice thickness is highly related to observed fast-ice thickness off the Russian coast;and (3)sea ice area/volume fluxes through the Fram Strait are in accord with the satellite-derived data.Generally,the coupled model successfully simulated the Arctic Ocean sea ice climatic variation.     

Formation and dynamics of melt waters of the sea ice cover

The model is constructed based on the concepts of the character of thermal evolution of the sea ice cover thickness. The dynamics of the ice thickness and that of the melt water forming in the ice cover are considered at the stage of melting. The space limitation of the marine environment for the ice is taken into account both for the stage of the ice cover formation and for the stage of its melting. The model is investigated analytically. The parametric identification of the model and the estimation of its adequacy are performed based on sampling distributions of the ice cover thickness in the Sea of Japan.     

STUDY ON SEA ICE WITH GMS REAL-TIME DATA

By use of GMS-4 infrared brightness temperature and visible albedo data from January toFebruary in 1995,the method for extracting of sea ice parameters is developed.The digital remotesensing picture is obtained on Liaodong Bay.Based on the difference in physical properties betweenice and water,a criterion distinguishing ice from water is set up.Ice thickness has been calculatedaccording to the relationship between ice thickness and brightness as well as albedo.Iceconcentration is retrieved due to the difference on albedo between ice and water.The resultsindicate that the accuracy of ice-water distinguishing is 84.8%,the errors of ice thickness and iceconcentration are 3.8 cm and 22%,respectively.     

STUDY ON SEA ICE WITH GMS REAL-TIME DATA*

By use of GMS-4 infrared brightness temperature and visible albedo data from January to February in 1995,the method for extracting of sea ice parameters is developed.The digital remote sensing picture is obtained on Liaodong Bay.Based on the difference in physical properties between ice and water,a criterion distinguishing ice from water is set up.Ice thickness has been calculated according to the relationship between ice thickness and brightness as well as albedo.Ice concentration is retrieved due to the difference on albedo between ice and water.The results indicate that the accuracy of ice-water distinguishing is 84.8%,the errors of ice thickness and ice concentration are 3.8 cm and 22%,respectively.     

基于MODIS产品的中国陆地冰云季节变化特征

利用2011年11月-2016年10月Terra卫星MODIS（moderate-resolution imaging spectroradiometer）3级大气产品数据（MOD08_M3）对中国陆地区域冰云发生概率、有效粒子半径、光学厚度和冰水路径的水平分布与季节变化进行分析。结果表明:冰云特性的水平分布和季节变化特征与东亚季风和强对流天气的发生存在一定联系。近5年冰云发生概率呈上升趋势,季节性变化规律明显,高值区出现在青藏高原东北部;冰云有效粒子水平分布呈现由西南向东北逐渐增加的趋势,总体季节性变化特点不明显,但在纬度较高地区出现随季节变化特征;冰云光学厚度与冰水路径水平分布和季节变化趋势大致相同,呈东南向西北递减趋势,总体季节性变化明显。     

青藏高原那曲夏季云中水成物分布特征的毫米波雷达观测

结合2014年7—8月第三次青藏高原大气科学试验获得的毫米波雷达资料与探空温度资料,利用模糊逻辑法反演了西藏那曲地区夏季云中水成物的相态并对其分布特征开展了研究。首先,分析了层积云、雨层云以及深对流云的典型个例,发现三类云反射率因子、多普勒速度、速度谱宽以及退偏振因子垂直分布均有较大差别,相应的云中水凝物的回波特征与相态分布差别也较大。其次,研究了液相、混合相和冰相云层的云雷达探测特征,发现液相云层在0℃层以下的暖云层和0℃层以上的过冷水云层均具有反射率因子高值中心,混合云层的反射率因子高值中心随高度上升变化不大,冰云层的反射率因子高值主要集中在6 km以上,且随高度上升而趋于集中;三种相态云层出现频率高值分别集中在地面以上1、2～3、3～4 km高度层;液相云层在上午出现频率最高,混合相云层高频率发生在下午,冰相云层在晚上的出现频率最高。三种相态云层出现在上午的高度与下午和晚上相比较低,出现在晚上的高度范围最大;液相云层厚度一般小于0.3 km,冰相云层云顶位于9 km左右高度层时平均厚度最大,中云内的混合相和冰相厚度变化较小。     

2005年渤海海冰冰厚热力增长特征实验的个例研究

认识渤海海冰冰厚热力增长特征,是开发利用海冰资源的理论基础.本文通过2005年1月12日-27日在辽东湾鲅鱼圈和渤海湾黄骅海冰现场实验个例研究得出:鲅鱼圈的累积冰厚平均日增量1.33 em/d,平均冰厚日变化为3 cm;黄骅的累计冰厚平均日增量为0.54 cm/d,平均冰厚变化22.3 cm;冰厚从0 cm增长到10 cm所需的时间为鲅鱼圈5 d左右,黄骅10 d左右;冰厚日变化与日平均气温和日平均冰温与之间相关性显著,但冰厚对气温和冰温降低的反应有一定的滞后性;当环境温度持续下降时,累积冰厚与累积气温之间有显著的正相关,当环境温度上升时,累积冰厚与累积气温之间相关性逆转.     

Some measurements and observations of very old sea ice and brackish ice,Ward Hunt Ice Shelf,N.W.T.

Abstract

Using ¹⁸O/¹⁶O ratio measurements, sea ice and brackish ice have been identified in a 10‐m ice core from Ward Hunt Ice Shelf. Brackish ice constitutes 62% of the core, and sea ice the remainder. The sea ice and brackish ice occur in alternating layers of 2–4 m thickness. The mean salinity of brackish ice (0.22) is an order of magnitude lower than that of the sea ice (1.26). The discrete sea and brackish ice layers and their individual salinity populations have been maintained apparently while the ice has aged and been raised about 40–50 m from the bottom of the ice shelf to its surface, a process taking roughly 400–500 years. Thin sections of the brackish ice reveal variable textures and an almost complete absence of cellular substructure that is associated with brine inclusion and retention in modern sea ice. Thin sections of the old sea ice show evidence of the former cellular substructure that appears to have been altered from the original. The discrete salinity populations and variable textures are briefly discussed.     

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.     

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。     

Application of a coupled ice‐ocean model to the Labrador Sea

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.     

粤北地区导线覆冰气象特征与标准厚度推算

利用广东省乐昌高山气象站1972—1978年观冰资料和气候资料,分析了粤北地区导线覆冰的气象特征,建立了导线覆冰标准冰厚的气象推算模型。根据乐昌国家气象站的历史资料,对乐昌高山气象站的气候资料进行订正延长,构建了乐昌高山气象站覆冰年极值长年代序列,并推算出离地不同高度各重现期的标准冰厚值。结果表明,粤北地区导线覆冰主要发生在1月,其次为2月和12月,平均覆冰期在90天左右,最长覆冰期可达131天以上。主导风向、日最低气温、日降水量是影响导线覆冰厚度的主要气象因素。标准冰厚的年极值序列服从极值I型概率分布,历史上的最大导线覆冰值出现在2008年1月26日,2m高度标准冰厚达64.4mm,15m高度标准冰厚达92.7mm,与2008年冰灾实况调查的覆冰厚度(标准冰厚)115mm较为接近。     

2006—2011年西藏纳木错湖冰状况及其影响因素分析

湖冰是气候变化的指示器,为分析纳木错地区气候对湖冰冰情的影响,利用2006—2011年西藏纳木错(面积2000km2)和白马纳木错(面积1.45 km2)湖冰的观测资料,结合MODIS遥感影像资料分析了两个湖泊完全冻结日期、完全解冻日期、封冻期、湖冰厚度的状况及其与气温和风速的关系。纳木错湖湖冰冰情主要受气温的影响,同时也受风速的影响。纳木错湖的完全冻结日期集中在2月,完全解冻日期在5月中旬,封冻期平均天数为90 d,封冻期与冬季负积温具有较好的对应关系。面积较小的白马纳木错冰情的年际波动较大,其平均封冻期为124 d。纳木错湖的最大冰厚一般出现在3月,其厚度为58~65 cm。     

基于CERES资料的新疆云物理参数时空分布特征

利用2011—2020年ERA5再分析降水资料、CERES云物理参数产品，分析新疆云参数的时空变化分布特征，归纳总结云物理参数与降水的相关性，结果表明：1）云水路径（冰相）值、云粒子有效半径（冰相）、云光学厚度与降水量的空间分布一致，均为山区最大，北疆次之，南疆最小。2）夏季（6—8月）在南、北疆、山区云水路径（液、冰相）、云顶（底）温度、云光学厚度与降水量呈同位相变化；云粒子有效半径（液、冰相）、云顶气压与降水量呈反位相变化。3）夏季（6—8月）北疆、山区的云水路径（液、冰相）值、云顶（底）温度、云光学厚度，南疆云光学厚度与降水量呈正相关；北疆云粒子有效半径（冰相），南疆云粒子有效半径（液相）、云顶气压，山区云粒子有效半径（液、冰相）、云顶气压与降水量呈负相关。     

Identification of ice properties in the Sea of Okhotsk using scattering index maps

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.