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  

贾建颖  孙照渤 《南京气象学院学报》2006,29(1):75-81

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   

区域气候模式中径流计算方案的数值试验   总被引：10，自引：2，他引：10  

齐丹  赵平  屠其璞  王开存 《南京气象学院学报》2006,29(6):782-789

采用由曼宁方程推导而来的动力波方程来改进陆面模式BATS中的径流计算方案，并将改进径流方案后的BA偈模式应用到区域气候模式RegCM2中。利用1998年6—8月T106资料做边界场，对改进后的区域气候模式在中国东部地区进行检验。模拟结果表明，改进后的方案在夏季6—8月内模拟的径流值达到80—500mm左右，较原方案模拟的径流量（30—80mm）更加接近径流实况（50—500mm），体现了径流的大尺度平流效应。取单站（武汉）的模拟结果与原模式进行比较，发现模拟场的平均气温与实况场的误差较原模式减小了0．66℃，几次明显的降水过程也有很好的模拟。文中还分析了气温、降水、土壤含水量、蒸发等量的模拟情况。  相似文献   

SLM和LPM模型日径流模拟对比分析——以陕西黑河为例     

赵静  李贺丽  陶林威 《地下水》2006,28(5):25-27

本文以黑河流域为例,根据可能收集的资料,试用SLM和LPM模型对日径流量进行了模拟和模拟精度检验,并对各模型的模拟结果作了对比分析,结果表明:①LPM可用于参考性预报,而SLM不能用于参考性预报,只能作参考性估报;②由于LPM模型吸收了季节变化信息,其检验期和率定期的评定效率均较高.结论:较之SLM,LPM模型的有效性和可靠性都有很大的提高,而且在一定程度上消减了洪峰预报误差,考虑了洪峰非线性变化的影响.  相似文献   

北极臭氧垂直分布和天气尺度变化的观测研究   总被引：2，自引：0，他引：2  

Zou Han  Zhou Libo  Jian Yongxiao  Liu Yu 《大气科学进展》2002,19(5):855-862

北极地区臭氧对北极气候和环境系统起着重要作用。研究其分布和变化有助于了解北极的气候和环境及其对全球气候系统的影响,有助于气候和环境变化的数值预报。中国北极科学探测1999在北冰洋楚可奇海域成功的进行了大气臭氧观测。通过在中国“雪龙”号破冰船甲板上（于1999年8月18-24日在75°N,160°W附近处）释放大气臭氧探空仪获得了高分辨率的大气垂直结构和臭氧分布资料,可以进行大气尺度的大气臭氧变化研究。分析大气监测资料、TOMS臭氧总量资料和NCEP大气环流资料表明,大气臭氧总量随着对流层顶的低一高一低变化呈高一低一高的变化过程。研究还表明,大气柱的臭氧总量与13公里以下的大气臭氧含量关系密切,而在约20公里处的大气臭氧浓度最大值的变化与整个气柱臭氧的关系不大。500 hPa天气形势图上一个弱一强一弱的西南天气型造成的弱臭氧平流可能是这次臭氧变化的主要原因。  相似文献   

NUMERICAL SIMULATIONS ON INFLUENCES OF VARIATION OF SEA ICE THICKNESS AND EXTENT ON ATMOSPHERIC CIRCULATION     

武炳义  黄荣辉  高登义 《Acta Meteorologica Sinica》2002,(2)

By using a 2-layer AGCM designed by Institute of Atmospheric Physics,Chinese Academy ofSciences.this paper investigates influences of thickness and extent variations in Arctic sea ice onthe atmosphere circulation,particularly on climate variations in East Asia.The simulation resuhshave indicated that sea ice thickness variation in the Arctic exhibits significant influences onsimulation results,particularly on East Asian monsoon.A nearly reasonable distribution of sea icethickness in the model leads directly to stronger winter and summer monsoon over East Asia.andimproves the model's simulation results for Siberia high and Icelandic low in winter.On the otherhand,sea ice thickness variation can excite a teleconnection wave train across Asian Continent,andin low latitudes,the wave propagates from the western Pacific across the equator to the easternPacific.In addition,the variation of sea ice thickness also influences summer convective activitiesover the low latitudes including South China Sea and around the Philippines.Effects of winter sea ice extents in the Barents Sea on atmospheric circulation in the followingspring and summer are also significant.The simulation result shows that when winter sea iceextent in the target region is larger (smaller) than normal.(1)in the following spring (averagedfrom April to June).positive (negative) SLP anomalies occupy the northern central Pacific.whichleads directly to weakened (deepened)Aleutian low.and further favors the light (heavy) sea icecondition in the Bering Sea:(2)in the following summer,thermal depression in Asian Continent isdeepened (weakened).and the subtropical high in the northwestern Pacific shifts northward(southward) from its normal position and to be strengthened (weakened).  相似文献   

Bioaccumulation of radiocaesium in Arctic seals     

Carroll J  Wolkers H  Andersen M  Rissanen K 《Marine pollution bulletin》2002,44(12):1366-1371

Seals are high trophic level feeders that bioaccumulate many contaminants to a greater degree than most lower trophic level organisms. Their trophic status in the marine food web and wide-spread distribution make seals useful sentinels of arctic environmental change. The purpose of this investigation is to document the levels and bioaccumulation potential of radiocaesium in high latitude seal species for which data have not previously been available. The study was carried out on harp, ringed, and bearded seals caught north of the island archipelago of Svalbard (82°N) in 1999. The results are then compared with previous studies in order to elucidate factors responsible for bioaccumulation in Arctic seals. Concentrations of ¹³⁷Cs were determined in muscle, liver and kidney samples from a total of 10 juvenile and one adult seal. The mean concentration in muscle samples for all animals was 0.23±0.045 Bq/kg f.w. ¹³⁷Cs concentrations in both liver and kidney samples were near detection limits (≈0.2 Bq/kg f.w.). The results are consistent with previous studies indicating low levels of radiocaesium in Arctic seals in response to a long term trend of decreasing levels of ¹³⁷Cs in the Barents Sea region. Bioconcentration factors (BCFs) estimated for seals from NE Svalbard are low, ranging from 34 to 130. Comparing these values with reported BCFs for Greenland seals from other sectors of the European Arctic, we suggest that the combination of physiological and ecological factors on radiocaesium bioaccumulation is comparable among different Arctic seal populations. The application of this work to Arctic monitoring and assessment programs is discussed.  相似文献   

Radiation Exchange Between Stratus Clouds and Polar Marine Surfaces     

D. Freese  Ch. Kottmeier 《Boundary-Layer Meteorology》1998,87(2):331-356

The radiative energy exchange between arctic sea-ice and stratiform clouds is studied by means of aircraft measurements and a two-stream radiation transfer model. The data have been obtained by flights of two identically instrumented aircraft during the Radiation and Eddy Flux Experiments REFLEX I in autumn 1991 and REFLEX II in winter 1993 over the arctic marginal ice zone of Fram Strait. The instrumental equipment comprised Eppley pyranometers and pyrgeometers, which measure the solar and terrestrial upwelling and downwelling hemispheric radiation flux densities, and a line-scan-camera on one aircraft to monitor the surface structure of the sea-ice. An empirical parametrization of the albedo of partly ice-covered ocean surfaces is obtained from the data, which describes the albedo increasing linearly with the concentration of the snow-covered sea-ice and with the cosine of the sun zenith angle at sun elevations below 10°. Cloud optical parameters, such as single scattering albedo, asymmetry factor and shortwave and longwave height-dependent extinction coefficient are determined by adjusting modeled radiation flux densities to observations. We found significant influence of the multiple reflection of shortwave radiation between the ice surface and the cloud base on the radiation regime. Consistent with the data, a radiation transfer model shows that stratus clouds of 400 m thickness with common cloud parameters may double the global radiation at the surface of sea-ice compared to open water values. The total cloud-surface-albedo under these circumstances is 30% larger over sea-ice than over water. Parametrizations of the global and reflected radiation above and below stratus clouds are proposed on the basis of the measurements and modeling. The upwelling and downwelling longwave emission of stratus clouds with thicknesses of more than 500 m can be satisfactorily estimated by Stefan's law with an emissivity of nearly 1 and when the maximum air temperature within the cloud is used.  相似文献   

不同植被类型对土壤全氮随降雨径流流失的控制研究--以抚仙湖流域磷矿开采区为例   总被引：1，自引：0，他引：1  

赵敏慧  杨树华  王宝荣 《云南地理环境研究》2006,18(4):20-26

地表径流挟带土壤氮进入水体是造成水体面源污染的主要途径之一。本研究依区域年降雨量的差异，将抚仙湖磷矿开采区年降雨量分别为1200-1300mm和1000-1100min的区域划分为东大河流域磷矿区和帽天山磷矿区两个研究单元，通过设置野外径流小区，在自然降雨状态下对磷矿开采废弃地与矿区现有主要植被类型土壤营养元全氮随径流流失量进行比较研究。研究结果表明：降雨强度是矿山废弃地产流的关键因子，在大、暴雨状态下矿山废弃地土壤TN流失量远大于各植被类型，对抚仙湖水质产生不利的影响。各植被类型土壤TN随径流流失量主要取决于地表径流量，径流中TN含量对其影响不大，流失总量次序与径流总量次序相一致，表现为：灌草丛〉云南松灌丛〉云南松混交林〉华山松林〉竹林〉桉树林，除灌草丛外各植被类型均能对土壤TN流失起到较强的截留作用。  相似文献   

用BATS模型模拟径流的个例研究   总被引：3，自引：0，他引：3  

刘春蓁  程斌 《水文》1998,(1):8-13

为了解陆气间水热交换在径表成中的作用,本文采用ＢＡＴＳ模型模拟了淮河流域山区和平原在１９９１年汛期５０天的暴雨洪水过程,计算了径流,土壤温度和感热,通量,并用常规的汇流计算方法得到了流域出口断量过程线。  相似文献   

年降水量和年径流量序列中特大（小）值分析处理方法研究     

曹升乐  于翠松 《水文》1998,(2):22-26

本文针对年降水量序列和年径流量序列中存在特大（小）值的问题,提出了实测序列中特大（小）值的检验方法及其重现期的确定方法,给出了含有特大值序列的分析计算方法。对山东省胶东地区部分主要河流年降水量和年径流量序列进行了分析,重新评价了该地区的降水资源及地表水资源。  相似文献