2008-2014年祁连山区夏季降水的日变化特征及其影响因素

基于中国自动气象站与CMORPH降水产品融合的逐时降水量0.1°×0.1°网格数据集通过逐时降水量、降水频率和降水强度等指标研究了2008-2014年祁连山区夏季降水的日变化特征,并结合ERA-Interim再分析资料分析了气象要素对降水日变化的影响。结果表明：① 祁连山区逐时平均降水量和降水频率的时空分布特征较为一致,即东中段大于西段,且7月最大,6月次之,8月最小;降水强度的空间分布则与降水量和降水频率的存在差异,且6月的降水强度平均值最大。② 白天和夜间的降水量均表现出东中段多于西段、山区多于平原的特点,并有明显的夜雨现象;从年际差异来看,2008-2014年白天和夜间的降水量均呈增加趋势。③ 祁连山区夏季降水平均相对变率介于5%~38%之间,全区20:00平均相对变率最大;逐时降水量和降水频率普遍存在较好的相关性,尤其是在东中段。④ 对比再分析资料发现,祁连山区降水日变化与相对湿度和地面温度等气象要素有关。     

The concentration variation features of sea salt ions and non sea salt ions in a firn core recovered from Princess Elizabeth Land, East Antarctica

A 51.85 m firn core drilled in Princess Elizabeth Land, Antarctica, during the 1996-1997 Chinese First Antarctic Inland Expedition, has been measured for δ 18 O and major ions. Based on the high quality data of the seasonal variations of major ions, the firn core was dated with errors within ±3 years. The 51.85 m firn core record extends for 251 years (A. D. 1745-1996). The results of the glaciochemistry data of the firn core show that the mean concentrations of Cl -, Na + and Mg 2+ are similar to those reported from other coastal areas in East Antarctica. However, mean concentrations of Ca 2+ are much higher than those reported from other regions, this anomaly phenomenon may be related to the strong local terrestrial sources. It is found that the variations of three kinds of sea salt ions (Cl -, Na + and Mg 2+ ) in the past 150 years show very similarly rising trends, which may be the results the Southern Hemisphere warming in the past century.     

南极地区数百年来气候变化的冰芯记录对比研究

随着国际横穿南极科学考察计划的实施, 近年来开展了沿中山站-Dome A考察路线的冰芯研究, 获得了伊丽莎白公主地250 a来气候环境变化的高分辨率记录. 通过与Lambert冰川流域西侧有关研究结果的对比, 揭示了该冰川谷地为东南极洲重要气候分界线的特征. 综合南极地区其它地点冰芯记录和冰盖变化研究结果, 发现以小冰期为代表的寒冷期在东南极洲较为明显, 在西南极洲则不明显, 甚或恰好相反, 表现为温暖阶段. 就东南极洲来说, 也存在明显的区域差异: 以Lambert冰川谷地为界, 东部地区, 如Wilkes Land (Law Dome), Victoria Land北部(Hercules Neve)等地, 小冰期冷期比较突出;西部地区, 如Dronning Maud Land和Mizuho高原, 情况不是很明确. Lambert冰川流域是非常特殊的地方, 虽然小冰期冷期也存在, 但1850年前后的显著高温和近100多年来的降温与南极洲其它地方都不一样, 而与南极半岛北侧一冰芯所给出的400 a温度变化记录极为相似, 我们尚不能解释为何如此遥远的两个地点具有很好的一致性而与其它地方则不一致.     

南极冰盖中nssSO42-和NO3-传输路径初探

总结了南极冰盖中 nss SO4 2 - 和 NO3- 的主要来源 ,通过对南极冰盖中几种主要离子空间分布特征的分析 ,结合南极冰盖中不同区域火山活动记录的时间差 ,认为南极冰盖中的nss SO4 2 - 和 NO3- 很可能是通过远距离高空传输到极地冰雪中 ,具体过程为 :nss SO4 2 - 和 NO3-在对流层顶部平流层底部呈带状输送到极地上空 ,然后辐射下沉 ,再辐散到其他地区     

Lambert冰川流域东西两侧气候环境变化特征

During the 1992-1993 joint Australian-Chinese over-snow traverse of the western Lambert Glacier Basin (LGB), two firn cores were drilled respectively at MGA and LGB16. During the 1996-1997 and 1997-1998 austral summers, two firn cores were drilled respectively at DT001 and DT085 on the eastern LGB. Based on the measurements made during the expeditions, the climatic and environmental features on both sides of the LGB have been studied. Results show that during the past 50 years, the trends of both air temperature and accumulation rate show a slight increase on the east side of the LGB, in contrast to the west side of the LGB. The spatial trends of the accumulation rate measured by accumulation canes at 2 km intervals along the nearly 500 km of the traverse lines on both sides of the LGB are different. Moreover, correlations of δ^18O vs T10 along the two sides of the LGB are also different. In addition, the variations of sea salt ion concentrations show different trends in the past 50 years. All the evidence shows that the Lambert Glacier is a dividing region for the different climatic regimes over the East Antarctic ice sheet, which may be due to different moisture resources resulting from special local circumfluence such as cyclone activities, local terrain influences.     

南极冰盖边缘近250年来气温变化的地域分布特征

通过对南极冰盖边缘17支浅冰芯氧同位素的对比研究,揭示了整个南极冰盖边缘近50年来、150年来和250年来气温变化的地域分布特征。近50年来,南极冰盖边缘的氧同位素温度有的呈现上升趋势,有的呈现下降趋势,但气温变化的地域规律性不强;近150年来,南极冰盖边缘的同位素温度的升高和降低趋势大致呈现出一种交替分布的态势;近250年来,南极冰盖边缘所有的氧同位素温度都记录了小冰期的降温事件。气温的这种地域分布特征可能是南大洋独特的环流形式--环南极波 (ACW) --在特殊地形 (如大的冰盆) 影响下,在南极冰盖边缘的表现形式,并且随着时间尺度的不同,南大洋独特的环流形式 、ACW和地形的影响强度各异。     

我国大气降水中稳定同位素研究进展

大气降水中稳定同位素的比率与降水产生过程中的气象条件密切相关,可以利用其时空分布特征来反演大气过程,示踪水汽来源,反映天气气候的区域性特征.对影响我国大气降水中稳定同位素组成与分布进行了总结,探讨了影响降水中氢氧同位素的因素及空间变化特征,并分别介绍了我国青藏高原区、西北干旱区和东部季风区等地区近年来降水中稳定同位素的...     

天山乌鲁木齐河源1号冰川雪层中NO_3~-的演化过程

根据2004年11月至2005年10月在天山乌鲁木齐河源1号冰川积累区采集的雪坑样品研究发现,雪层中NO3-平均浓度存在季节性变化特征,湿季（4~10月）的NO3-浓度明显低于干季（11月至次年3月）。特别是在春季,在雪层上部出现的浓度峰,经过夏季淋溶改造,稀释并合并为稳定的浓度峰;雪层中各浓度峰普遍处于向下迁移的过程...     

Selected Trace Elements in Snowpack on Urumqi Glacier No. 1, Eastern Tianshan, China: As Yielded by Leaching Treatment Representative of Real-World Environmental Conditions

To investigate the seasonal variability and potential environmental significance of trace elements in mountain glaciers, the surface snow and snow pit samples were collected at Urumqi Glacier No. 1 (43o06'N, 86o49'E, 4 130 m a.s.l.), eastern Tianshan (天山), from September 2002 to September 2003, and analyzed for Li, V, Cr, Mn, Co, Cu, and Ba. The samples were acidified (leached) in a manner intended to reasonably approximate the extent to which the natural hydrologic and weathering cycles would liberate elem...     

1961–2011年中国南方地区极端降水事件变化(英文)

Based on the daily precipitation from a 0.5°×0.5° gridded dataset and meteorological stations during 1961–2011 released by National Meteorological Information Center, the reliability of this gridded precipitation dataset in South China was evaluated. Five precipitation indices recommended by the World Meteorological Organization(WMO) were selected to investigate the changes in precipitation extremes of South China. The results indicated that the bias between gridded data interpolated to given stations and the corresponding observed data is limited, and the proportion of the number of stations with bias between –10% and 0 is 50.64%. The correlation coefficients between gridded data and observed data are generally above 0.80 in most parts. The average of precipitation indices shows a significant spatial difference with drier northwest section and wetter southeast section. The trend magnitudes of the maximum 5-day precipitation(RX5day), very wet day precipitation(R95), very heavy precipitation days(R20mm) and simple daily intensity index(SDII) are 0.17 mm·a–1, 1.14 mm·a–1, 0.02 d·a–1 and 0.01 mm·d–1·a–1, respectively, while consecutive wet days(CWD) decrease by –0.05 d·a–1 during 1961–2011. There is spatial disparity in trend magnitudes of precipitation indices, and approximate 60.85%, 75.32% and 75.74% of the grid boxes show increasing trends for RX5 day, SDII and R95, respectively. There are high correlations between precipitation indices and total precipitation, which is statistically significant at the 0.01 level.