共查询到19条相似文献，搜索用时 312 毫秒
1.
黄土粒度组成的古环境意义研究进展 总被引：1，自引：0，他引：1
中国黄土高原的黄土与古土壤序列完好地记录了250万年以来的全球气候变化情况,被认为是反映第四纪古气候和古环境的重要载体.阐述了黄土粒度研究现状与进展,黄土的粒度组成、磁化率、粒度分形等及其所反映的古环境意义. 相似文献
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在研究古气候时,经常假定东亚夏季风与冬季风变化是反位相的,即冬季风强时夏季风弱,夏季风强时冬季风弱。Zhang等和Zhou等对此提出了质疑,Yancheva等做了回答。一般并没有充分的证据表明冬、夏季风变化总是反位相的。事实上,冬、夏季风变化的关系,还要从时间尺度也就是形成原因上探讨。地球轨道尺度Shi等研究了284 kaBP以来的东亚冬、夏季风的代用资料,并与模式模拟的结果作了比较。用三宝洞与葫芦洞石笋δ18O反映夏季风的强度,用西峰等3个站的黄土粒度反映冬季风的强度,发现夏季风强度变化与20 ka的岁差周 相似文献
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沙尘气溶胶是地球上分布最广的自然气溶胶类型之一,也是气候系统中的重要成分。沙尘天气严重影响人类生产、生活和居住环境,对气候变化也存在显著作用。近年来,沙尘气溶胶的气候效应得到越来越多的关注和研究,但人们的工作主要集中在对现代沙尘气溶胶的研究,而对过去沙尘气溶胶气候效应的研究不多。本研究利用黄土粒度及沉积特征,根据现代沙尘暴的沉降特点,研究了60 kaB.P以来中国黄土高原南部地区沙尘气溶胶的辐射效应,结果表明：1）沙尘气溶胶产生的辐射效应主要表现在造成行星系统太阳辐射反射量的普遍增加,即沙尘过程具有明显的降温效应。2）气候效应上主要表现为对气候的负反馈。由沙尘粒度引起的行星反照率在全新世适宜期达最大值,而在冰期有最小值出现;在气候降温事件中,沙尘气溶胶造成行星反照率降低;每一次降温事件发生时气溶胶的降温效应会相应减弱。约60 kaB.P以来沙尘气溶胶给年均温度带来的影响是使其平均降幅在－0.8 K左右。3）利用黄土的粒度分布,结合现代气溶胶的观测可以估算地质时期沙尘气溶胶的气候效应。 相似文献
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《干旱气象》2015,(5)
通过对沙漠—黄土过渡带杨桥畔全新世风成砂—砂质黄土—砂质古土壤型地层序列的粒度、磁化率、硅铁铝率和全铁含量等多项气候环境代用指标的综合分析,并结合光释光(OSL)与14CAMS测年结果资料,探讨了近万年以来该地区的古气候环境演化过程。研究结果表明:13.0~11.7ka B.P.,气候干冷,环境恶劣,沙漠处于扩张活化阶段;11.7~10.0 ka B.P.,气候趋于略温干,沙漠处于半固定—半流动状态;10.0~6.4 ka B.P.,气候温和偏湿,为该地区全新世适宜期,沙漠处于(半)固定状态;6.4~1.6 ka B.P.,气候偏冷干,沙漠处于半固定—半流动状态;1.6~0 ka B.P.,气候继续向冷干方向发展,并且存在着气候冷暖频繁交替。 相似文献
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通过对1994年南海17940孔硅藻数据进行分析,结果表明：该孔硅藻组合中菱形海线藻及其变种T. nitzschioides var. parva的百分含量比值具有一定的变化规律。通过比对南海17940孔已有温度记录（有孔虫G. rubberδ18O数据、FP-12E表层海水年平均温度）,进一步发现菱形海线藻变种（T. nitzschioides var. parva）与原种的比值所反应的温度变化与原有记录具有较好的一致性。其中,比值增加反映了古温度的升高;反之则说明气候变冷。因此,该比值可反映出自晚更新世末期以来该地区古温度的变化情况,是较好的古温度指示标志。 相似文献
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第七届全国气溶胶学术会议于1999年9月6～10日在西安召开。会议由中国颗粒学会气溶胶专业委员会发起,中国科学院地球环境研究所黄土与第四纪地质国家重点实验室和联合国开发计划署(UNDP)西安306项目共同承办。会议主题为：气溶胶、环境、气候。 相似文献
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中国西北黄土地区地震崩滑的分布与宏观影响因素 总被引：4，自引：0，他引：4
在中国黄土高原划分了9个震害区,分析研究了中国西北黄土地区地震崩滑的分布与宏观影响因素。研究结果认为,位于六盘山西侧、会宁以东的第4区地震崩滑最发育;可以产生黄土地震崩滑的最大震中距或区域最大面积都与震级有关;影响黄土地区地震崩滑敏感性的宏观因素包括活动地质构造、地震断层、地层、地形、水文条件、地震强度等。坡度>2°的黄土斜坡就有可能发生地震滑坡,高烈度可以削弱或消除微地形对地震滑坡的影响。与现代地形具有相似性的埋藏地形、高达黏土层或砂层的地下水位、新黄土地层等,可加重地震滑坡的发育;而一定位置的下更新统砾岩层、老黄土等则可起到抗滑作用。中国西北黄土地区产生地震崩落、滑移的最低震级分别为4、5级,或地震烈度5度。在第4震害区,烈度6～7度就可能产生明显的地震崩滑;10度以上可形成较大面积的崩滑群;7(1/2)、8级以上的地震可分别产生滑陷、流滑。多因素组合对滑坡的影响可能不同于单因素,但比单因素更重要。 相似文献
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基于粒度特征区分风尘序列中沙尘暴降尘和流动沙丘沙组分对探究环境演变、重建风尘活动强度有重要意义。以塔克拉玛干沙漠中部流动沙丘沙和沙漠南缘策勒绿洲现代大气降尘为研究对象,分析其粒度差异,并与中国其他地区沙丘沙进行对比。结果表明：（1）塔干沙漠沙漠沙丘沙粒度分布曲线以单峰分布为主,策勒绿洲尘暴降尘呈双峰分布;（2）塔干沙漠沙丘沙和降尘均呈分选较好、近对称分布和中等峰态,但沙丘沙粒径粗;（3）不同区域沙丘沙的相同粒径组分相对含量和粒度特征具有相似性。尽管沙丘沙和大气降尘均有较好的分选性,但风场强度的差异导致它们的粒径分布范围、偏态和峰度不同。研究结果可为沙漠边缘区域地层中的风成组分判别提供依据。 相似文献
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High frequency pulses of East Asian monsoon climate in the last two glaciations: link with the North Atlantic 总被引：20，自引：0，他引：20
Three loess sections in the Loess Plateau of China have been studied to characterize the variations of the East Asian monsoon
climate in the Late Quaternary period. Paleo-weathering profiles based on two weathering indices reveal a series of spatially
correlative intervals of lower weathering intensity (LW), in the last glacial and late penultimate glacial loess, indicating
significantly cooler or/and drier conditions. Most of them are identified at or near the transitional boundaries between loess
and soil units, suggesting that climatic conditions favorable for LW events tended to occur at or near major climatic boundaries.
Twenty-eight radiocarbon and thermoluminescence measurements, combined with Kukla's magnetic susceptibility age model date
these events at ∼14, ∼21, ∼29, ∼38, ∼52, ∼71, ∼135, and ∼145 ka BP, with ∼5–10 ka frequency inlaid within the orbitally induced
∼20-ka periodicity. The ages of the first six events in the last glacial period are therefore close to those of the coarse-grained
Heinrich layers in the North Atlantic Ocean, which resulted from massive discharges of icebergs. The results indicate that
the climate in the area affected by the East Asian monsoon has experienced high-frequency changes more or less synchronous
with the Heinrich events. These high-frequency changes have been reported by Porter and An, based on the grain-size time series
from the Luochuan loess section. Our data also reveal that similar events also occurred during the penultimate glaciation.
The mechanisms linking the Heinrich events and the East Asian monsoon climate may be similar to that driving the Younger Dryas
event which has been identified in a large number of records in China and in the surrounding oceans.
Received: 16 October 1995 / Accepted: 10 May 1996 相似文献
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构建一个经济-气候新模型评价气候变化对粮食产量的影响 总被引：8，自引：1，他引：7
将气候变化研究和农业经济研究相结合,构建了一个经济-气候新模型,用来评价全球气候变化对粮食产量影响的问题。提出在经济模型C-D生产函数中添加气候变化因子,建立一个新的评价模型,作为连接气候变化因素和经济变化因素的桥梁,并对该模型的性能及合理性进行了初步的模拟和验证。 相似文献
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基于SPEI指数的河北省南部夏玉米生长季干旱特征分析 总被引：1，自引：0，他引：1
利用河北省南部8个气象站点1962—2018年的逐月气温、降水量数据,采用标准化降水蒸散指数(SPEI),通过小波分析、Mann-Kendall检验等方法,分析了河北省南部夏玉米生长季(6—9月)干旱变化特征以期为干旱灾害的监测、预报预警及防御提供理论依据。结果表明:夏玉米苗期干旱发生频率为31.5%,1966年后苗期气候呈湿润化趋势,在1968和2009年附近可能发生了气候湿润化的突变,整个分析期(1962—2018年)干湿变化包含13～18a、5～8a周期振荡;夏玉米穗期干旱发生频率为40.3%,2006年后穗期气候呈持续干旱化趋势,在1980和1997年附近可能发生了气候干旱化的突变,整个分析期干湿变化包含15～22a、6～10a周期振荡;夏玉米花粒期干旱发生频率为29.8%,1989年后花粒期气候呈持续干旱化趋势,可能在1992和2002年附近发生了气候干旱化的突变;夏玉米生长季干旱发生频率约为30%,生长季气候总体呈干旱化趋势,特别是1997年后持续干旱化,可能在1996年附近发生了气候干旱化的突变。 相似文献
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WANG Futang 《Acta Meteorologica Sinica》2001,15(4):498-508
Increasing the concentration of greenhouse gases in the atmosphere will strengthen the naturalgreenhouse effect,which could lead to global climate warming and more other changes.China is alargely agricultural country with a large size of population and the relative shortages of farminglands and water resources,thus increasing the importance of climate warming for national economydevelopment.Therefore,Chinese government and scientists have paid great attention to theimpact-assessment of climate warming on national economy in China,especially during the past 10years.This presentation will briefly describe some major issues of climate warming impact researchon national vegetation,agriculture,forest,water resources,energy use and regional sea level forChina,etc.As a result,all climate change scenarios derived by GCMs suggest a substantial change in thecharacteristic natural vegetation types.It is also shown that comparing with the distributionsimulated under the normal time period 1951—1980 as the present climate,by 2050 large changesin cropping systems would occur almost everywhere in China.Climate warming would lead toincrease cropping diversification and multiplication.Unfortunately,the possible net balancebetween precipitation and evapotranspiration would be negative and it would lead to reduce thegrain production in China significantly due to enhanced moisture stress in soil.The most evidentinfluence of climate warming on water resources would happen in Huanghe-Huaihe-Haihe Basin andthe water supply-demand deficit would be substantially enhanced in this area.And also,a warmerclimate for China will alter the energy requirement for domestic heating and cooling,that is,reduce energy use for heating in northern China and increase energy consumption for cooling insouthern China. 相似文献
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Yanmin Yang De Li Liu Muhuddin Rajin Anwar Heping Zuo Yonghui Yang 《Theoretical and Applied Climatology》2014,115(3-4):391-410
Conceptions encompassing climate change are irreversible rise of atmospheric carbon dioxide (CO2) concentration, increased temperature, and changes in rainfall both in spatial- and temporal-scales worldwide. This will have a major impact on wheat production, particularly if crops are frequently exposed to a sequence, frequency, and intensity of specific weather events like high temperature during growth period. However, the process of wheat response to climate change is complex and compounded by interactions among atmospheric CO2 concentration, climate variables, soil, nutrition, and agronomic management. In this study, we use the Agricultural Production Systems sIMulator (APSIM)-wheat model, driven by statistically downscaled climate projections of 18 global circulation models (GCMs) under the 2007 Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios (SRES) A2 CO2 emission scenario to examine impact on future wheat yields across key wheat growing regions considering different soil types in New South Wales (NSW) of Australia. The response of wheat yield, yield components, and phenology vary across sites and soil types, but yield is closely related to plant available water capacity (PAWC). Results show a decreasing yield trend during the period of 2021–2040 compared to the baseline period of 1961–1990. Across different wheat-growing regions in NSW, grain yield difference in the future period (2021–2040) over the baseline (1961–1990) varies from +3.4 to ?14.7 %, and in most sites, grain number is decreased, while grain size is increased in future climate. Reduction of wheat yield is mainly due to shorter growth duration, where average flowering and maturing time are advanced by an average of 11 and 12 days, respectively. In general, larger negative impacts of climate change are exhibited in those sites with higher PAWC. Current wheat cultivars with shorter growing season properties are viable in the future climate, but breading for early sowing wheat varieties with longer growing duration will be a desirable adaptation strategy for mitigating the impact of changing climate on wheat yield. 相似文献
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The climate observation data,reanalysis data,and grain/soybean yields per unit area were used to analyze and interpret the impact of climate change on grain production.The results show that Jilin Province was located in a remarkable increase area of temperature during the growing season(May-September)from 1948 in the middle latitudes of the Northern Hemisphere.The mid-west and south of Jilin Province and Liaoning Province were located in a clear linear decrease tendency area of annual precipitation,wherein a warm/dry tendency of climate change dominated,while the east of Jilin Province lay in a clear linear decrease tendency area of annual precipitation.The climate warming played an important role in continuous increase in the grain yield per unit area since the 1980's in the main grain production areas of Jilin Province,however,from the end of the 20th century to the beginning of the 21st century,the beneficial effect seemed to be not obvious any longer,the grain yield per unit area fluctuated with annual precipitation. 相似文献
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The climate observation data, reanalysis data, and grain/soybean yields per unit area were used to analyze and interpret the impact of climate change on grain production. The results show that Jilin Province was located in a remarkable increase area of temperature during the growing season (May-September) from 1948 in the middle latitudes of the Northern Hemisphere. The mid-west and south of Jilin Province and Liaoning Province were located in a clear linear decrease tendency area of annual precipitation, wherein a warm/dry tendency of climate change dominated, while the east of Jilin Province lay in a clear linear decrease tendency area of annual precipitation. The climate warming played an important role in continuous increase in the grain yield per unit area since the1980's in the main grain production areas of Jilin Province, however, from the end of the 20th century to the beginning of the 21st century, the beneficial effect seemed to be not obvious any longer, the grain yield per unit area fluctuated with annual precipitation. 相似文献
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分析了天水市1960-2005年干旱气候特征,包括温度、降水等气候因子及土壤水分、干旱频次等变化特点。结果表明,20世纪90年代为近46 a来降水的最低值,进入21世纪后,降水变率明显增大。气温自20世纪60年代总体呈上升趋势,特别是90年代以来上升趋势明显,土壤蒸散发加大。20世纪90年代土壤含水量最少,水分亏缺最为严重,春旱、初夏旱、伏旱出现几率最多。根据46 a来干旱气候变化特点及其对主要粮食作物生长的影响,引进影响系数,对主要夏、秋粮作物种植风险程度进行评估,并运用线性风险决策模式, 提出适应干旱气候特点的当地主要粮食作物种植比例调整方案。 相似文献
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气候变化引起水热条件的变化,从而影响到我国农业生产的方方面面,人们采取不同措施以适应气候变化带来的各种影响。为了清楚地认识气候变化对我国主要粮食作物生产的影响以及适应措施,利用《中国农业统计年鉴》1980-2007年资料和1961-2007年全国逐日平均温度观测数据及前人的研究成果,分析了气候变化对我国三大粮食作物布局和种植结构的影响。结果表明,由于气候变暖,粮食作物种植比例变化明显。小麦种植比例对气候变化最为敏感,波动大;水稻种植比例变化南北方反向,且变化幅度趋缓;玉米种植比例持续增加,增幅加大。三大粮食作物种植结构变化均以2000年为分界点,呈现不同增减趋势。而作物熟制、复种指数也发生明显变化,种植北界持续北推。黑龙江地区大面积扩种水稻,原来的玉米优势种植区为水稻所替代。 相似文献