海冰和海温对西北地区中部6月降水异常的协同影响

利用1961年以来美国国家环境预报中心(NCEP)月平均再分析风场、高度场、NOAA重构海表温度以及西北地区中部54个气象站6月逐日降水资料、1979年以来北极10个区域的海冰面积,通过分析2019年6月西北地区中部降水异常的成因,揭示出对该区域6月降水具有显著影响的关键海区海冰面积及时段、北大西洋三极子(NAT)关键...     

2005年北极冰川首期GPS监测

2005年7月至8月,中国北极黄河站第二次科学考察期间,科考队员针对黄河站附近首次队踏勘选定的两条典型冰川(AustreLov啨nbreen和Pedersenbreen),开展了以监测冰川物质平衡和冰川运动为主要内容的研究课题。本文分析了利用差分GPS进行北极冰川运动监测的可行性和优越性;初步处理了首期GPS监测的数据,并进行了精度分析,得出了较为满意的结果;针对北极冰川特殊的地理环境,探讨了在北极冰川上进行GPS测量应该注意的问题。     

The relationship between ENSO cycle and temperature,precipitation and runoff in the Qilian mountain area

El Nino and La Nina are the events concerned internationally. The corresponding relationship between E1 Nino events, temperature, precipitation and runoff in the Qilian mountain area are analyzed according to the date fi‘om the weather and the hydrometric stations in the area, the results show that effects of E1 Nino events to temperature, precipitation and runoff are different in the different time and zones. When E1 Nino occurs, temperature rises, but precipitation and runoff decrease in the whole Qilian mountain area, especially in the east and middle parts of the area. Temperature rises, precipitation and runoff still decrease in the eastern Qilian mountain area in the next year El Nino occurring, but decrease extent is fewer. There are not obvious relationship between temperature,precipitation and runoff with El Nino events in the western Qilian mountain area.     

The relationship between ENSO cycle and temperature, precipitation and runoff in the Qilian mountain area

El Nino and La Nina are the events concerned internationally. The corresponding relationship between El Nino events, temperature, precipitation and runoff in the Qilian mountain area are analyzed according to the date from the weather and the hydrometric stations in the area, the results show that effects of El Nino events to temperature, precipitation and runoff are different in the different time and zones. When El Nino occurs, temperature rises, but precipitation and runoff decrease in the whole Qilian mountain area, especially in the east and middle parts of the area. Temperature rises, precipitation and runoff still decrease in the eastern Qilian mountain area in the next year El Nino occurring, but decrease extent is fewer. There are not obvious relationship between temperature, precipitation and runoff with El Nino events in the western Qilian mountain area.     

近50年来ENSO与祁连山区气温、降水和径流的对应关系

El Nino and La Nina are the events concerned internationally. The correspondingrelationship between El Nino events, temperature, precipitation and runoff in the Qilian mountain areaare analyzed according to the date from the weather and the hydrometric stations in the area, theresults show that effects of El Nino events to temperature, precipitation and runoff are different in thedifferent time and zones. When El Nino occurs, temperature rises, but precipitation and runoff decreasein the whole Qilian mountain area, especially in the east and middle parts of the area. Temperaturerises, precipitation and runoff still decrease in the eastern Qilian mountain area in the next year ElNino occurring, but decrease extent is fewer. There are not obvious relationship between temperature,precipitation and runoff with El Nino events in the western Qilian mountain area.     

中国北方春季沙尘暴频数与北半球500hPa高度场的SVD分析

选取1957-2000年中国北方地区春季沙尘暴发生次数资料和北半球500hPa秋、冬、春季的平均高度场资料,对沙尘暴和高度场作SVD分析。结果表明,我国北方春季沙尘暴次数各地具有比较一致的变化趋势,表明可能与大尺度气候背景的变化有联系。变化的最敏感区域为内蒙古中西部地区、新疆西部、青海西部和东北地区。我国北方春季沙尘暴发生次数与同期及前期500hPa高度场有较好的相关关系,前期环流形势对春季沙尘暴频数有一定的指示和预测意义,冬季环流场尤其具有预报指示意义,因为前一年冬季北大西洋涛动对我国春季北方沙尘暴发生次数有影响。     

The relationship between NDVI and precipitation on the Tibetan Plateau

The temporal and spatial changes of NDVI on the Tibetan Plateau, as well as the relationship between NDVI and precipitation, were discussed in this paper, by using 8-km resolution multi-temporal NOAA AVHRR-NDVI data from 1982 to 1999. Monthly maximum NDVI and monthly rainfall were used to analyze the seasonal changes, and annual maximum NDVI, annual effective precipitation and growing season precipitation (from April to August) were used to discuss the interannual changes. The dynamic change of NDVI and the corre-lation coefficients between NDVI and rainfall were computed for each pixel. The results are as follows: (1) The NDVI reached the peak in growing season (from July to September) on the Tibetan Plateau. In the northern and western parts of the plateau, the growing season was very short (about two or three months); but in the southern, vegetation grew almost all the year round. The correlation of monthly maximum NDVI and monthly rainfall varied in different areas. It was weak in the western, northern and southern parts, but strong in the central and eastern parts. (2) The spatial distribution of NDVI interannual dynamic change was different too. The increase areas were mainly distributed in southern Tibet montane shrub-steppe zone, western part of western Sichuan-eastern Tibet montane coniferous forest zone, western part of northern slopes of Kunlun montane desert zone and southeastern part of southern slopes of Himalaya montane evergreen broad-leaved forest zone; the decrease areas were mainly distributed in the Qaidam montane desert zone, the western and northern parts of eastern Qinghai-Qilian montane steppe zone, southern Qinghai high cold meadow steppe zone and Ngari montane desert-steppe and desert zone. The spatial distribution of correlation coeffi-cient between annual effective rainfall and annual maximum NDVI was similar to the growing season rainfall and annual maximum NDVI, and there was good relationship between NDVI and rainfall in the meadow and grassland with medium vegetation cover, and the effect of rainfall on vegetation was small in the forest and desert area.     

青藏高原植被覆盖变化与降水关系

The temporal and spatial changes of NDVI on the Tibetan Plateau, as well as the relationship between NDVI and precipitation, were discussed in this paper, by using 8-km resolution multi-temporal NOAA AVHRR-NDVI data from 1982 to 1999. Monthly maximum NDVI and monthly rainfall were used to analyze the seasonal changes, and annual maximum NDVI, annual effective precipitation and growing season precipitation (from April to August) were used to discuss the interannual changes. The dynamic change of NDVI and the corre- lation coefficients between NDVI and rainfall were computed for each pixel. The results are as follows: (1) The NDVI reached the peak in growing season (from July to September) on the Tibetan Plateau. In the northern and western parts of the plateau, the growing season was very short (about two or three months); but in the southern, vegetation grew almost all the year round. The correlation of monthly maximum NDVI and monthly rainfall varied in different areas. It was weak in the western, northern and southern parts, but strong in the central and eastern parts. (2) The spatial distribution of NDVI interannual dynamic change was different too. The increase areas were mainly distributed in southern Tibet montane shrub-steppe zone, western part of western Sichuan-eastern Tibet montane coniferous forest zone, western part of northern slopes of Kunlun montane desert zone and southeastern part of southern slopes of Himalaya montane evergreen broad-leaved forest zone; the decrease areas were mainly distributed in the Qaidam montane desert zone, the western and northern parts of eastern Qinghai-Qilian montane steppe zone, southern Qinghai high cold meadow steppe zone and Ngari montane desert-steppe and desert zone. The spatial distribution of correlation coeffi- cient between annual effective rainfall and annual maximum NDVI was similar to the growing season rainfall and annual maximum NDVI, and there was good relationship between NDVI and rainfall in the meadow and grassland with medium vegetation cover, and the effect of rainfall on vegetation was small in the forest and desert area.     

极点对称模态分解下中国新疆温度变化趋势的区域特征

基于新疆16个国际交换站1957-2012年年平均温度时间序列,利用极点对称模态分解(ESMD)方法,分析了新疆温度序列的非线性趋势变化特征,并对其空间差异进行了初步探讨。结果表明：50多年来,新疆年平均温度整体上呈现出显著的非线性上升趋势,且其变化存在明显的年际尺度(2年和8年)和年代际尺度(10年和25年);各分量方差贡献率显示年际变化在新疆整体温度变化中占据主导地位,重构的年际变化趋势能精细刻画原始温度序列在研究时期内的波动状况;重构的年代际变化揭示了新疆在1997年前后气候模态有了显著转换,由原来温度以负相位为主的气候模态转向正相位显著的高温气候模态;年平均温度非线性变化趋势具有明显的区域差异,北疆以上升为主,东疆表现出先降后升,南疆变化较为复杂。同时,结果还表明ESMD是一种很好的甄别大尺度循环和非线性趋势的方法。     

NDVI prediction over Mongolian grassland using GSMaP precipitation data and JRA-25/JCDAS temperature data

An algorithm to predict the NDVI (Normalized Difference Vegetation Index) distribution over Mongolia, which is based on a stepwise multiple linear regression analysis, has been developed using global precipitation data obtained from satellites and global surface air temperature data obtained from the reanalysis data during the period 1998–2005. This algorithm can predict the NDVI value up to 1–3 months in advance for a grid with a spatial resolution of 0.25° × 0.25°.In order to validate the algorithm, the NDVI distribution was predicted for the period from May to November 2006 using 1 to 3-month prediction algorithms. The distributions of the predicted normalized anomalies agreed well with those of the observed normalized anomalies. It was found that these algorithms were effective for arid and semi-arid regions, despite its low accuracy for August and regions with high vegetation activity.     

Coordinated changes of sea ice over the Beaufort and Chukchi seas: regional and seasonal perspectives

One outstanding feature of the recent Arctic climate is the contrast of the changes of sea ice concentration and thickness between the Beaufort Sea and the Chukchi Sea. Since the Arctic Oscillation (AO) plays a critical role in driving Arctic sea ice changes and the Beaufort and Chukchi seas have been hypothesized as a region in which sea ice anomalies originate, we employed a coupled sea ice-ocean model and carried out simulations forced by the AO signal to examine sea ice changes in these regions, focusing on seasonality. With the AO phase transition from negative to positive, anticyclonic windstress weakens broadly in both winter and summer; however, the surface air temperature response shows remarkable seasonal dependence. Positive temperature anomalies spread over the entire domain in winter, while negative anomalies occur in the shelf seas in summer, although positive anomalies remain in the deep-water portion. The simulated sea ice concentration resembles the observed concentration. The strong seasonality of sea ice concentration changes suggests that accumulation of sea ice concentration in the Beaufort Sea and reduction in the Chukchi Sea are mainly produced in summer. Changes of ice thickness are robust through the seasonal cycle. Generally, sea ice dynamics play a critical role in creating the anomalous sea ice pattern and sea ice thermodynamics partially compensate the dynamically-driven changes. However, considerable seasonal differences occur.     

北半球积雪/海冰面积与温度相关性的差异分析

积雪和海冰的时空变化对区域以及全球的气候、水文具有重要影响。基于雪冰数据和NCEP再分析气温数据,利用MK检验、滞后分析等方法,分析了积雪、海冰的时空变化特征及其与温度的相关特征。结果表明：1979-2013年,北半球积雪区、北极圈的年均温度呈显著上升的趋势,而积雪面积和海冰面积呈显著下降的趋势。在大部分地区,积雪覆盖频率随着温度的上升呈显著减少的趋势,但在中国长江中下游、青藏高原等局部地区,积雪覆盖频率随着温度的上升呈显著增加趋势。在大部分的近陆地海域,海冰覆盖频率随着温度的上升呈显著下降趋势。超前时间1~2个月的温度与海冰面积的负相关性最高。超前1~4个月的温度与积雪面积的负相关性最高。温度对海冰的影响时间比对积雪的影响时间长1~2个月。温度变化对海冰和积雪的影响存在一致性,但积雪和海冰对温度的响应时间存在差异,具有空间变异性。     

The coupled characteristics of the physical process between sea ice of two poles and Tibetan land surface

In order to discuss the characteristics of sea ice change of strong signal area on Antarctic and Arctic and the correlation between the thermal state on the land surface of Tibetan Plateau and the atmosphere circulation of North Hemisphere or the climate changes in China, and to study the feedback mechanism among “three-pole” factors, the earlier stage “three-pole” strong signal characteristics by using statistic methods such as teleconnection,which affect the regional climate changes in China and East Asia. The cross-correlation feature and coupling effect between ice caps of North and South pole and water-thermal state on Tibetan Plateau surface are discussed as well. The contribution of three-pole's earlier stage factors to China's summer climate change and the influence of its dynamic structure are compared here. The formation mechanisms of global climate change and regional climate change of China are investigated from the aspect of qualitative correlation mode of global sea-land-air-ice.     

黑河流域中上游地区降水中氢氧同位素与温度关系研究

根据黑河流域中上游地区所取得的降水水样和降水气象资料,分析了该区域降水中氢氧同位素随温度的变化特征,研究了内陆河黑河流域中上游地区降水中氢氧同位素与温度的关系,揭示了降水中氢氧同位素随温度的变化规律。降水中氢氧同位素与温度有很好的正相关关系,且与降雨前后平均气温之间的相关性优于与降雨前和降雨后气温之间的,温度与δ~(18)O之间的相关性优于与δD的。在黑河流域,局地性降水的增加影响降水中氢氧同位素与温度之间的关系,在山前或山前盆地,因局地性降水增加,所以降水中氢氧同位素与温度的关系与山区相比较差。     

The influence of river discharge on the thawing of sea ice, Mackenzie River Delta: albedo and temperature analyses

Multi-temporal satellite images, field observations and field measurements were used to investigate the mechanisms by which sea ice melts offshore from the Mackenzie River Delta. Satellite data recorded between April and August 1986 were corrected to a map projection and calibrated such that albedo and temperature values could be compared. Three stages in the melting of sea ice were identified: flooding (overflows), insolation and melting by warm river water. The albedo values of overflows were as much as 1/7 that of ice values while the albedo of ice decreased by 1/3 over the summer. Approximately two weeks after the overflows develop, sea surface temperatures rise as the river-discharge peaks and becomes the dominant source of energy. By this process, ice removal in the delta regime is initiated two months earlier than adjacent coasts with minimal runoff. However, the net result is only a two-week acceleration of ice removal in the delta region.     

南极无冰区典型沉积环境石英砂表面结构特征及其在沉积环境识别中的应用

本文利用电镜扫描方法 (SEM)对比分析了南极乔治王岛无冰区海滩沉积、冰碛物以及阿德雷岛湖泊沉积等典型沉积环境中的石英砂表面结构特征 ,得出了乔治王岛各典型沉积环境中石英砂表面结构特征的颗粒频率曲线。结果表明 :不同沉积环境下的石英砂颗粒表面结构特征具有相似性 ,这主要和南极地区广泛发育的冰川作用有关 ,同时 ,它们也有各自典型的特征组合 ,这些典型特征组合的不同反映了石英砂后期的搬运历史和沉积环境的差异。本文还依据石英砂表面特征的颗粒出现频率 ,利用聚类分析方法对研究区内三级海岸阶地上的沉积物和一个未知成因的样品进行了沉积环境的判别分析 ,结果证明石英砂微形貌特征可以作为南极地区沉积环境识别的有效手段     

Distribution of winter-spring snow over the Tibetan Plateau and its relationship with summer precipitation in Yangtze River

The distribution of winter-spring snow cover over the Tibetan Plateau(TP) and its relationship with summer precipitation in the middle and lower reaches of Yangtze River Valley(MLYRV) during 2003–2013 have been investigated with the moderate-resolution imaging spectrometer(MODIS) Terra data(MOD10A2) and precipitation observations. Results show that snow cover percentage(SCP) remains approximately 20% in winter and spring then tails off to below 5% with warmer temperature and snow melt in summer. The lower and highest percentages present a declining tendency while the middle SCP exhibits an opposite variation. The maximum value appears from the middle of October to March and the minimum emerges from July to August. The annual and winter-spring SCPs present a decreasing tendency. Snow cover is mainly situated in the periphery of the plateau and mountainous regions, and less snow in the interior of the plateau, basin and valley areas in view of snow cover frequency(SCF) over the TP. Whatever annual or winter-spring snow cover, they all have remarkable declining tendency during 2003–2013, and annual snow cover presents a decreasing trend in the interior of the TP and increasing trend in the periphery of the TP. The multi-year averaged eight-day SCP is negatively related to mean precipitation in the MLYRV. Spring SCP is negatively related to summer precipitation while winter SCP is positively related to summer precipitation in most parts of the MLYRV. Hence, the influence of winter snow cover on precipitation is much more significant than that in spring on the basis of correlation analysis. The oscillation of SCF from southeast to northwest over the TP corresponds well to the beginning, development and cessation of the rain belt in eastern China.     

中国北方农牧交错带春季风速的年际变化与冬季海温的关系

利用中国北方农牧交错带1979—2016年64个气象台站的逐日风速资料、ERSST海温数据以及ERA-Interim再分析资料,探讨了前期冬季海温与北方农牧交错带春季风速年际变化的关系。研究表明,北方农牧交错带春季的风速存在强烈的逐年波动,年际方差占总方差的比例为36%。影响农牧交错带春季风速年际变化的前期冬季海温在北大西洋20°N~65°N区域呈现“负、正、负”的异常分布,在北太平洋10°N~55°N、130°W~180°区域呈现“负、正”的异常分布。冬季的海温异常与研究区春季风速年际变化联系的桥梁是北半球大尺度大气环流的异常。当北大西洋海温从高纬至低纬呈现“负、正、负”的异常分布时,从北大西洋至东亚位势高度呈明显的“正、负、正、负”的波列特征;当北太平洋海温从高纬至低纬呈现“负、正”的异常分布时,从北太平洋至东亚位势高度呈“负、正、负、正、负、正”的三波型分布。二者均能影响东亚地区春季大气环流的变化,导致东亚地区上空产生一个异常的气旋性环流,该气旋性环流在对流层中层与低层均存在,是造成研究区风速变化的直接原因。冬季海温与研究区春季风速的显著相关,说明冬季海温对农牧交错带春季风速的年际变化具有超前指示意义。利用北大西洋和北太平洋海温异常中心区的冬季海温作为预报因子,建立春季风速预报模型,可以解释风速年际变化的32%,回报交叉验证结果表明,海温与风速的时间滞后关系是显著和稳健的。     

青藏高原夏季上空水汽含量演变特征及其与降水的关系(英文)

By using the observed monthly mean temperature and humidity datasets of 14 radiosonde stations and monthly mean precipitation data of 83 surface stations from 1979 to 2008 over the Tibetan Plateau(TP),the relationship between the atmospheric water vapor(WV) and precipitation in summer and the precipitation conversion efficiency(PEC) over the TP are analyzed.The results are obtained as follows.(1) The summer WV decreases with increasing altitude,with the largest value area observed in the northeastern part of the TP,and the second largest value area in the southeastern part of the TP,while the northwestern part is the lowest value area.The summer precipitation decreases from southeast to northwest.(2) The summer WV presents two main patterns based on the EOF analysis:the whole region consistent-type and the north-south opposite-type.The north-south opposite-type of the summer WV is similar to the first EOF mode of the summer precipitation and both of their zero lines are located to the north of the Tanggula Mountains.(3) The summer precipitation is more(less) in the southern(northern) TP in the years with the distribution of deficient summer WV in the north while abundant in the south,and vice versa.(4) The PEC over the TP is between 3% and 38% and it has significant spatial difference in summer,which is obviously bigger in the southern TP than that in the northern TP.