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1.
利用1979—2016年ERA-interim逐日再分析资料,定义了青藏高原臭氧谷(Ozone Valley over the Tibetan Plateau,OVTP)极端和普通强(弱)事件,并讨论了其特征。结果表明:1) OVTP极端强事件在夏秋季节多发,10月最多,频率达2. 0%; OVTP普通强事件在春夏季多发,7月最多,频率达1. 7%。OVTP极端弱事件在秋冬季多发,12月最多,频率达3. 8%; OVTP普通弱事件在冬季多发,1月最多,频率达2. 0%。2) OVTP极端强事件出现频率显著增加(0. 004%·a~(-1)),极端弱事件出现频率显著减少(-0. 015%·a~(-1))。OVTP普通事件的变化均不显著。3) OVTP极端强事件的面积和强度均在秋季最大,10月达到最大值,面积为4. 3×10~5km~2,强度为1. 5×10~5t; OVTP普通强事件的面积和强度均在夏季最大,7月达到峰值,面积为1. 7×105km~2,强度为4. 1×10~3t。OVTP极端弱事件的面积和强度在春夏较小,4月达到最小值,面积为3. 2×10~4km~2,强度为1. 1×10~2t; OVTP普通弱事件的面积和强度在春夏秋均较小,4月和10月达到极小值,4月面积为2. 5×10~4km~2,强度为68 t,10月面积为2. 2×10~4km~2,强度为97t。4) OVTP极端和普通强事件的面积(强度)均呈显著增大(增强)趋势,极端强事件的面积达2. 5×10~2km~2·a~(-1),强度达2. 5×10~2t·a~(-1),普通强事件的面积达4. 5×10~2km~2·a~(-1),强度达4. 5 t·a~(-1)。极端和普通弱事件的面积(强度)均呈显著减小(减弱)趋势,极端弱事件的面积达-1. 7×10~4km~2·a~(-1),强度达-7. 0×10~3t·a~(-1),普通弱事件的面积达-2. 3×10~3km~2·a~(-1),强度达-2. 7×102t·a~(-1)。 相似文献
2.
北极海冰变化的时间和空间型 总被引：14，自引：0，他引：14
利用 4 4a(195 1～ 1994年 )北极海冰密度逐月资料 ,分析提出了一种与北极冰自然季节变化相吻合的分季法 ,并根据这种分季法 ,使用EOF分解 ,揭示了北极各季海冰面积异常的特征空间型及其对应的时间变化尺度。结果表明 :(1)北极冰面积异常变化的关键区 ,冬季 (2～ 4月 )主要位于北大西洋一侧的格陵兰海、巴伦支海和戴维斯海峡以及北太平洋一侧的鄂霍次克海和白令海 ,夏季 (8～ 10月 )则主要限于从喀拉海、东西伯利亚海、楚科奇海到波佛特海的纬向带状区域内 ,格陵兰海和巴伦支海是北极海冰面积异常变化的最重要区域 ;(2 )春 (5～ 7月 )、秋 (11月～次年 1月 )季各主要海区海冰面积异常基本呈同相变化 ,夏季东西伯利亚海、楚科奇海、波佛特海一带海冰面积异常和喀拉海呈反相变化 ,而冬季巴伦支海、格陵兰海海冰面积异常和戴维斯海峡、拉布拉多海、白令海、鄂霍次克海的海冰变化呈反相变化 ;(3)北极冰总面积过去 4 4a来确实经历了一种趋势性的减少 ,并且叠加在这种趋势变化之上的是年代尺度变化 ,其中春季 (5～ 7月 )海冰面积异常变化对年平均北极冰总面积异常变化作出了主要贡献 ;(4)位于北太平洋一侧极冰面积异常型基本具有半年的持续性 ,而位于北大西洋一侧极冰面积异常型具有半年至一年的持续性 相似文献
3.
北极海冰的气候变化与20世纪90年代的突变 总被引：5，自引：0，他引：5
应用英国Had ley气候研究中心1968~2000年的1°×1°的北半球逐月海冰密集度资料,使用EOF分解等统计方法,探讨北极海冰的气候变化趋势、海冰的突变、海冰的季节持续性和各季的特色。结果表明:(1)自1968年以来,北极海冰的减小是北半球海冰变化的总趋势;海冰的趋势变化在海冰的年际总变化中占有相当重要的地位,可达50%左右。冬春季主要减少区域在格陵兰海、巴伦支海和白令海;夏秋季海冰减少是唯一趋势,中心在北冰洋边缘的喀拉海、拉普捷夫海、东西伯利亚海、楚科奇海、波弗特海。(2)20世纪80年代中后期北极海冰已出现减小趋势,在20世纪90年代,海冰又出现范围和面积的突然减少,中心在格陵兰海和巴伦支海;即海冰减少是加速的,其变化程度已远远超过一般的自然变化。(3)海冰有很好的季节持续性,有很强的隔季相关,也有较好的隔年相关;各季节海冰分布型之间有很好的联系,表现为海冰分布型的总体变化趋势是一致的,在海冰的减少中也体现了分布型的特征。 相似文献
4.
北极海冰和北半球500hPa极涡的相互关系 总被引：7，自引：0，他引：7
利用NCEP/NCAR 2.5°×2.5°的500 hPa高度场月平均再分析资料和1°×1°的海冰资料分别计算了北半球500 hPa极涡面积、极涡强度指数和北极海冰面积指数,分析了它们的经向分布、周期变化以及长期变化趋势中的突变。结果表明,海冰和极涡在经向分布上有明显差异,就东西半球而言它们的相对位置也不一样。除了都具有4个月、准半年、准1 a、4~5 a和10 a的共同周期外,还呈现出各自的周期变化。北极海冰面积自20世纪80年代以来呈明显减小趋势,北半球极涡面积也呈减小趋势,但是它们发生突变的时间却完全不同。海冰与极涡面积有显著的正相关关系,但海冰和极涡强度、极涡面积和极涡强度之间的关系却纷繁复杂。 相似文献
5.
Delving into the relationship between autumn Arctic sea ice and central–eastern Eurasian winter climate 
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下载免费PDF全文 《大气和海洋科学快报》2016,(5)
北极海冰的快速减少是否已经显著地影响了最近中纬度大陆冬季极端天气气候事件引起了气候学家的广泛争论。问题的争论是来源于观测数据的年限很短以及中高纬度复杂的内部变率。在本研究中,采用气候突变检测的方法,我们将秋季海冰覆盖面积的变化分为三个阶段:1979–1986(高海冰阶段),1987–2006(海冰缓慢减少阶段)和2007–2014(海冰快速减少阶段)。然后,我们分析了与每一个阶段秋季海冰变化相联系的中-东欧亚地区冬季气候(尤其极端天气事件)是什么。结果表明北极海冰减少对西伯利亚西部和东亚极端天气事件影响的信号是稳健可测的。伴随着海冰的快速减少,高低空急流速度的减弱和急流位置的南移;波动振幅的加强、乌拉尔山阻塞频率的增多。这些导致了寒潮事件从亚洲中部到中国东北部地区显著增多。并且,与北极海冰的快速减少相关的环流异常与观测到的环流异常基本一致。相反地,在高海冰阶段,与海冰相关的环流异常和观测的异常并不一致。这个阶段的环流异常是与北极涛动处于持续的负位相有关的。 相似文献
6.
基于1951—2019年NCEP/NCAR再分析资料、Hadley环流中心海温、海冰密集度资料,通过合成分析和诊断温度异常方程,研究不同类型ENSO对初冬北极海冰的影响。结果表明,EP La Ni1a发展年初冬(11—12月),巴伦支—喀拉海海冰异常减少;CP La Ni1a发展初冬,巴伦支—喀拉海海冰异常增加。EP和CP型El Ni1o对初冬北极海冰的影响类似：格陵兰海海冰异常减少,而哈德逊—巴芬湾海冰异常增加。不同类型ENSO对初冬北极海冰的影响主要通过产生不同的大气遥相关,引起同期和前期的海表气温异常而实现。 相似文献
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8.
北极海冰变化及其与中国秋季气温的相关分析 总被引：3，自引：0，他引：3
采用Hadley中心1953年1月—2003年2月逐月1°×1°海冰密集度资料和中国1951年1月—2001年2月160站逐月气温资料,对北极海冰的4个区域进行了研究,并考察了主要影响区与我国秋季气温的关系。结果表明:近50 a北极各区海冰在不同季节几乎都有显著的线性下降趋势,欧洲部分减少最快;海冰突变开始时间不同,春夏季大约在20世纪70年代、秋冬季在80年代左右;各区域海冰周期变化具有年代际特征,同时又有显著的季节差异和地域特性。主要影响区海冰与我国秋季气温的显著相关区在河套、长江中游和新疆的部分地区。不同区域海冰的显著相关时段不同,基本集中在海冰超前气温1~2 a的时间里。 相似文献
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10.
利用Hadley海冰密集度资料和NCEP/NCAR再分析资料,分析了北极海冰融冰量及其与大气变量年际关系的年代际变化。结果表明,北极海冰存在显著的年代际变化,且有较强的区域性。东西伯利亚海和波弗特海海冰融冰量的平均值变大且方差增大,格陵兰岛以东洋面海冰融冰量的量值和变率均在减弱。对3个不同气候时段内北极海冰融冰量进行EOF分解,前两个模态均在3个气候时段发生显著的年代际变化,东西伯利亚海海冰融冰量的增加与EOF第一模态年代际变化相关,而EOF第二模态则明显造成了波弗特海海冰的年代际消融。并且,与之相应的大气环流也出现了明显的年代际变化,它们与AO/NAO的年际关系也存在年代际转折,融冰量第二模态与AO的年际关系更为紧密,1960—1990年第二模态与AO的相关系数仅为0.186,而1980—2010年相关系数已升高至0.367。整个北冰洋的海冰融冰量与AO的年际关系也出现了年代际增强,尤其是东西伯利亚地区海冰融冰量与AO的年际关系发生了年代际增强,1980—2010年两者相关达到了0.4以上。而波弗特海融冰量与AO相关系数变化较大,1960—1990年其的相关系数高达-0.488,1980年后却减少至0.161。然而AO却未发生明显的年代际变化。造成北极海冰融冰量及其与大气变量年际关系发生年代际变化的主要因子之一是波弗特高压,其年代际减弱使得极区向东西伯利亚海和波弗特海的海冰输送减弱,导致这两个区域海冰减少,使得AO与北极海冰的年际关系发生了年代际转折。 相似文献
11.
Ford Victoria L. Frauenfeld Oliver W. Nowotarski Christopher J. Bombardi Rodrigo J. 《Climate Dynamics》2021,56(11):3541-3552
As Arctic sea ice declines in response to climate change, a shift from thick multiyear ice to a thinner ice cover is occurring. With this transition, ice thicknesses approach a threshold below which ice no longer insulates the atmosphere from oceanic surface fluxes. While this is well known, there are no estimates of the magnitude of this threshold, nor of the proportion of sea ice area that is below this threshold as ice thins. We determine this threshold by simulating the atmospheric response to varying thicknesses, ranging from 0.0 to 2.0 m and determine that threshold to be 0.40–0.50 m. The resulting “effective” ice area is 4–14% lower than reported total ice area, as 0.39–0.97 × 106 km2 of the total ice area falls below the threshold throughout the twentieth century, including during notable ice minima. The atmosphere above large non-insulating ice-covered regions is susceptible to more than 2 °C of warming despite ice presence. Observed mean Arctic Ocean ice thickness is projected to fall below this threshold as early as the mid-2020s. Studies on ocean–atmosphere interactions in relation to sea ice area should focus on this insulating sea ice area, where ice is at least 0.40–0.50 m thick, and treat ice regions below 0.40–0.50 m thickness with caution.
相似文献12.
This study examines pre-industrial control simulations from CMIP5 climate models in an effort to better understand the complex relationships between Arctic sea ice and the stratosphere, and between Arctic sea ice and cold winter temperatures over Eurasia. We present normalized regressions of Arctic sea-ice area against several atmospheric variables at extended lead and lag times. Statistically significant regressions are found at leads and lags, suggesting both atmospheric precursors of, and responses to, low sea ice; but generally, the regressions are stronger when the atmosphere leads sea ice, including a weaker polar stratospheric vortex indicated by positive polar cap height anomalies. Significant positive midlatitude eddy heat flux anomalies are also found to precede low sea ice. We argue that low sea ice and raised polar cap height are both a response to this enhanced midlatitude eddy heat flux. The so-called "warm Arctic, cold continents" anomaly pattern is present one to two months before low sea ice, but is absent in the months following low sea ice, suggesting that the Eurasian cooling and low sea ice are driven by similar processes. Lastly, our results suggest a dependence on the geographic region of low sea ice, with low Barents–Kara Sea ice correlated with a weakened polar stratospheric vortex, whilst low Sea of Okhotsk ice is correlated with a strengthened polar vortex. Overall, the results support a notion that the sea ice, polar stratospheric vortex and Eurasian surface temperatures collectively respond to large-scale changes in tropospheric circulation. 相似文献
13.
Song Feng Chang-Hoi Ho Qi Hu Robert J. Oglesby Su-Jong Jeong Baek-Min Kim 《Climate Dynamics》2012,38(7-8):1359-1373
The ecosystems in the Arctic region are known to be very sensitive to climate changes. The accelerated warming for the past several decades has profoundly influenced the lives of the native populations and ecosystems in the Arctic. Given that the K?ppen-Trewartha (K-T) climate classification is based on reliable variations of land-surface types (especially vegetation), this study used the K-T scheme to evaluate climate changes and their impact on vegetation for the Arctic (north of 50°N) by analyzing observations as well as model simulations for the period 1900–2099. The models include 16 fully coupled global climate models from the Intergovernmental Panel on Climate Change Fourth Assessment. By the end of this century, the annual-mean surface temperature averaged over Arctic land regions is projected to increase by 3.1, 4.6 and 5.3°C under the Special Report on Emissions Scenario (SRES) B1, A1b, and A2 emission scenarios, respectively. Increasing temperature favors a northward expansion of temperate climate (i.e., Dc and Do in the K-T classification) and boreal oceanic climate (i.e., Eo) types into areas previously covered by boreal continental climate (i.e., Ec) and tundra; and tundra into areas occupied by permanent ice. The tundra region is projected to shrink by ?1.86?×?106?km2 (?33.0%) in B1, ?2.4?×?106?km2 (?42.6%) in A1b, and ?2.5?×?106?km2 (?44.2%) in A2 scenarios by the end of this century. The Ec climate type retreats at least 5° poleward of its present location, resulting in ?18.9, ?30.2, and ?37.1% declines in areal coverage under the B1, A1b and A2 scenarios, respectively. The temperate climate types (Dc and Do) advance and take over the area previously covered by Ec. The area covered by Dc climate expands by 4.61?×?106?km2 (84.6%) in B1, 6.88?×?106?km2 (126.4%) in A1b, and 8.16?×?106?km2 (149.6%) in A2 scenarios. The projected redistributions of K-T climate types also differ regionally. In northern Europe and Alaska, the warming may cause more rapid expansion of temperate climate types. Overall, the climate types in 25, 39.1, and 45% of the entire Arctic region are projected to change by the end of this century under the B1, A1b, and A2 scenarios, respectively. Because the K-T climate classification was constructed on the basis of vegetation types, and each K-T climate type is closely associated with certain prevalent vegetation species, the projected large shift in climate types suggests extensive broad-scale redistribution of prevalent ecoregions in the Arctic. 相似文献
14.
The impact of Arctic sea ice on the Arctic energy budget and on the climate of the Northern mid-latitudes 总被引：1，自引：1，他引：0
The atmospheric general circulation model EC-EARTH-IFS has been applied to investigate the influence of both a reduced and a removed Arctic sea ice cover on the Arctic energy budget and on the climate of the Northern mid-latitudes. Three 40-year simulations driven by original and modified ERA-40 sea surface temperatures and sea ice concentrations have been performed at T255L62 resolution, corresponding to 79?km horizontal resolution. Simulated changes between sensitivity and reference experiments are most pronounced over the Arctic itself where the reduced or removed sea ice leads to strongly increased upward heat and longwave radiation fluxes and precipitation in winter. In summer, the most pronounced change is the stronger absorption of shortwave radiation which is enhanced by optically thinner clouds. Averaged over the year and over the area north of 70° N, the negative energy imbalance at the top of the atmosphere decreases by about 10?W/m2 in both sensitivity experiments. The energy transport across 70° N is reduced. Changes are not restricted to the Arctic. Less extreme cold events and less precipitation are simulated in sub-Arctic and Northern mid-latitude regions in winter. 相似文献
15.
利用1961—2015年Hadley中心逐月海表温度资料、海冰密集度资料以及NCEP/NCAR再分析资料,探讨了秋季北极海冰对于EP型ENSO事件的异常响应,并进一步研究了这种异常响应的可能原因。结果表明,秋季北极海冰对EP型ENSO的响应具有非线性,特别是喀拉海海域(60°～90°E,70°～80°N)海冰无论在EP型El Ni?o或是La Ni?a位相,均表现为显著的负异常。进一步研究发现,不同ENSO位相造成该区域海冰异常偏少的机制有明显不同。EP型El Ni?o年秋季菲律宾附近海域对流活动被抑制,所激发的经向波列在高纬地区形成异常反气旋环流,其南风分量向喀拉海输送暖平流,造成海冰异常偏少。而EP型La Ni?a年喀拉海海域则主要受到来自大西洋开放性海域西风异常的影响,合成结果和个例年均显示EP型La Ni?a年秋季北大西洋上空存在一个显著的西风急流中心,有利于北大西洋开放性海域较暖海水向下游输送,进而影响喀拉海海冰。这些结果表明,热带外地区大气环流场对EP型ENSO的非线性响应导致了喀拉海海冰对EP型ENSO事件的响应也表现出明显的非线性。 相似文献
16.
Jinfei WANG Hao LUO Qinghua YANG Jiping LIU Lejiang YU Qian SHI Bo HAN 《大气科学进展》2022,39(10):1591-1597
Seasonal minimum Antarctic sea ice extent (SIE) in 2022 hit a new record low since recordkeeping began in 1978 of 1.9 million km2 on 25 February, 0.17 million km2 lower than the previous record low set in 2017. Significant negative anomalies in the Bellingshausen/Amundsen Seas, the Weddell Sea, and the western Indian Ocean sector led to the new record minimum. The sea ice budget analysis presented here shows that thermodynamic processes dominate sea ice loss in summer through enhanced poleward heat transport and albedo–temperature feedback. In spring, both dynamic and thermodynamic processes contribute to negative sea ice anomalies. Specifically, dynamic ice loss dominates in the Amundsen Sea as evidenced by sea ice thickness (SIT) change, while positive surface heat fluxes contribute most to sea ice melt in the Weddell Sea. 相似文献
17.
Mean climatic characteristics in high northern latitudes in an ocean-sea ice-atmosphere coupled model 总被引：5，自引：2，他引：3
Emphasizing the model‘s ability in mean climate reproduction in high northern latitudes, resultsfrom an ocean-sea ice-atmosphere coupled model are analyzed. It is shown that the coupled model cansimulate the main characteristics of annual mean global sea surface temperature and sea level pressurewell, but the extent of ice coverage produced in the Southern Hemisphere is not large enough. The maindistribution characteristics of simulated sea level pressure and temperature at 850 hPa in high northernlatitudes agree well with their counterparts in the NCEP reanalysis dataset, and the model can reproducethe Arctic Oscillation (AO) mode successfully. The simulated seasonal variation of sea ice in the NorthernHemisphere is rational and its main distribution features in winter agree well with those from observations.But the ice concentration in the sea ice edge area close to the Eurasian continent in the inner Arctic Oceanis much larger than the observation. There are significant interannual variation signals in the simulated seaice concentration in winter in high northern latitudes and the most significant area lies in the GreenlandSea, followed by the Barents Sea. All of these features agree well with the results from observations. 相似文献
18.
FGOALS_gg1.1极地气候模拟 总被引：4，自引：0，他引：4
对中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室发展的气候系统模式FGOALS_g1.1的极地气候模拟现状进行了较为全面的评估.结果表明,FGOALS_g1.1对南北极海冰的主要分布特征、季节变化和年代际变化趋势具有一定的模拟能力.但也注意到,与观测相比,模式存在以下几方面的问题:(1)模拟的海冰总面积北极偏多,而南极偏少.北极,北大西洋海冰全年明显偏多;夏季,西伯利亚沿海海冰偏多,而波弗特海海冰偏少.南极,威德尔海和罗斯海冬季海冰偏少.南北极海冰边缘都存在异常的较大范围密集度很小的碎冰区,夏季尤为显著.(2)海冰流速在南北极海冰边缘和南极大陆沿岸附近较大.北极,模式没能模拟出波弗特涡流,并且由于模式网格中北极点的处理问题,造成其附近错误的海冰流场及厚度分布.这些海冰偏差与模式模拟的大气和海洋状况有着密切的联系.进一步分析表明,FGOALS_g1.1模拟的冰岛低压和南极绕极西风带明显偏弱,其通过大气环流和海表面风应力影响向极地的热量输送,在很大程度上导致上述的海冰偏差.此外,耦合模式中大气-海冰-海洋的相互作用可以放大子模式中的偏差. 相似文献
19.
利用1979~2012年青藏高原125个基本、基准站观测日最高及最低气温数据、Hadley中心月平均海冰覆盖率资料、ERA-Interim的风场、高度场等再分析资料,根据相关统计分析、合成分析等方法系统地分析了青藏高原地区秋、冬季冷昼和冷夜日数(低温日数)与关键影响海区海冰的关系及影响机理。结果表明,夏、秋季关键海区海冰偏少时,秋、冬季极地和青藏高原地区500 h Pa位势高度减小,中高纬西伯利亚地区位势高度增强,北极至青藏高原有明显由北向南波动通量,高压反气旋系统在西伯利亚地区形成与壮大,青藏高原以北风场呈现明显偏北风,Rossby波在青藏高原及其以北地区呈现由北向南波动形式,青藏高原以北的西风带地区Rossby波东传减缓,导致经向活动加强,北部冷空气易于通过气流向高原侵袭,秋、冬季青藏高原低温日数将偏多。 相似文献
20.
Unprecedented low twentieth century winter sea ice extent in the Western Nordic Seas since A.D. 1200
M. Macias Fauria A. Grinsted S. Helama J. Moore M. Timonen T. Martma E. Isaksson M. Eronen 《Climate Dynamics》2010,34(6):781-795
We reconstructed decadal to centennial variability of maximum sea ice extent in the Western Nordic Seas for A.D. 1200–1997
using a combination of a regional tree-ring chronology from the timberline area in Fennoscandia and δ18O from the Lomonosovfonna ice core in Svalbard. The reconstruction successfully explained 59% of the variance in sea ice extent
based on the calibration period 1864–1997. The significance of the reconstruction statistics (reduction of error, coefficient
of efficiency) is computed for the first time against a realistic noise background. The twentieth century sustained the lowest
sea ice extent values since A.D. 1200: low sea ice extent also occurred before (mid-seventeenth and mid-eighteenth centuries,
early fifteenth and late thirteenth centuries), but these periods were in no case as persistent as in the twentieth century.
Largest sea ice extent values occurred from the seventeenth to the nineteenth centuries, during the Little Ice Age (LIA),
with relatively smaller sea ice-covered area during the sixteenth century. Moderate sea ice extent occurred during thirteenth–fifteenth
centuries. Reconstructed sea ice extent variability is dominated by decadal oscillations, frequently associated with decadal
components of the North Atlantic Oscillation/Arctic Oscillation (NAO/AO), and multi-decadal lower frequency oscillations operating
at ~50–120 year. Sea ice extent and NAO showed a non-stationary relationship during the observational period. The present
low sea ice extent is unique over the last 800 years, and results from a decline started in late-nineteenth century after
the LIA. 相似文献