不同边界条件对多年冻土上限影响的模型试验研究   总被引：17，自引：10，他引：17  

冯文杰  李东庆  马巍  张鲁新 《冰川冻土》2001,23(4):353-359

在全球气候转暖对多年冻土影响的情景下，开展了在多模式下气温升高对冻土上限的影响试验研究。针对不加抛石遮阳棚、加抛石、加抛石遮阳棚3种情况，地表温度均采取基本温度加2次不同升温冻融循环，每次温控指标逐级提高0.5℃，即地表温度3次变化依次按照-16.1～5.8～-13.3℃、-15.6～6.3～-12.8℃、-15.1～6.8～-12.3℃进行，结果表明，加抛石及遮阳棚对多年冻土上限有着明显的影响，冻土上限的变化与气温基本上呈正相关，为寒区道路工程设计与施工提供了理论参考依据。  相似文献   

An abrupt cooling event early in the last interglacial in the northern South China Sea     

TU Xia  ZHENG Fan  Wang Jiliang  CAI Huimei  WANG Pinxian  C.Bühring  M.Sarnthein 《中国科学D辑(英文版)》2001,44(10):865-870

The high-resolution quantitative analysis of the planktonic foraminifera and the δ¹⁸O records of the section between 96.49– 137.6 mcd at ODP Site 1144 on the continental slope of northern South China Sea reveals an abrupt cooling event of sea surface temperature (SST) during the last interglacial (MIS 5.5, i.e. 5e). The dropping range of the winter SST may come to 7.5°C corresponding to 1.2‰ of the δ¹⁸O value of sea surface water. This event is comparable with those discovered in the west Europe and the northern Atlantic Ocean, but expressed in a more intensive way. It is inferred that this event may have been induced by middle- to low-latitude processes rather than by polar ice sheet change. Since the Kuroshio-index speciesPulleniatina obliquiloculata displayed the most distinct change at the event, it may also be related to the paleoceanographic change of the low-latitude area in the western Pacific Ocean. This event can be considered as one of “Younger Dryas-style coolings” and is indicative of climate variability of the last interglacial stage.  相似文献   

内江市近40年日照变化的统计特征   总被引：22，自引：1，他引：22  

谭友邦  谢利娟 《气象》1996,22(10):27-30

利用１９６０－１９９５年内江市各测站的逐月日照时数资料，分析了内江市近４０年来日照的变化特征，发现区域平均日照以４６．９８小时／１０年的倾向率减少，这种减少趋势主要表现在冬、夏两季。同时还检测出内江市区域平均年日照时数在１９８０年发生突变，共后进入一个相对少日照对段。  相似文献   

北半球50条山地冰川近期的物质平衡状况   总被引：4，自引：0，他引：4       下载免费PDF全文

杨大庆 《水科学进展》1992,3(3):161-165

近期北半球大多数山地冰川的物质平衡为负,冰川普遍退缩,表明北半球气候暖化的趋势.由于区域气候波动和变化的差异性以及冰川对气候变化的敏感性(响应程度)的不同,北半球山地冰川在普遍退缩的背景下具有鲜明的区域特征.  相似文献   

Climate change of the last millennium inferred from borehole temperatures: regional patterns of climatic changes in the Czech Republic — Part III     

L. Bodri  V. ermk 《Global and Planetary Change》1999,21(4):383

Accurate temperature–depth profiles may help to assess the temperature variations associated with the climate changes in the past. Ninety-eight ground surface temperature histories inverted from the temperature–depth borehole logs drilled on the territory of the Czech Republic [Bodri, L., ermák, V., 1995. Climate changes of the last millennium inferred from borehole temperatures: results from the Czech Republic — Part I. Global Planet. Change 11, pp. 111–125; Bodri, L., ermák, V., 1997. Climate changes of the last two millennia inferred from borehole temperatures: results from the Czech Republic — Part II. Global Planet. Change 14, pp. 163–173.] are used to reconstruct the regional patterns of the respective climate change. The climate was mapped for the following periods: 1100–1300 A.D. (Little Climatic Optimum), 1400–1500 A.D., 1600–1700 A.D. (main phase of the Little Ice Age), and for the most recent climate trend after year 1960. Comparison of the obtained maps with the meteorological observations and proxy climatic reconstructions confirmed good applicability of the “geothermal” paleoclimatic reconstructions for the regional studies.  相似文献   

On the Epochal Variability in the Frequency of Cyclones during the Pre-Onset and Onset Phases of the Monsoon over the North Indian Ocean     

P. P. BABURAJ  S. ABHILASH  K. MOHANKUMAR  A. K. SAHAI 《大气科学进展》2020,37(6):634-651

In this paper we examine the epochal changes in the frequency of cyclones over the North Indian Ocean during the pre-onset and onset phases of the monsoon. We consider three epochs; namely, the early(1955-74), middle(1975-94) and recent(1995-2014) epochs. It is found that the number of cyclones in the Bay of Bengal(BOB) decreases throughout the three epochs. Over the Arabian Sea(ARB), however, there is a decrease in the early epoch, before then reaching a minimum in the middle epoch followed by an increase in the recent epoch, thus exhibiting epochal variability. Dynamic and thermodynamic parameters along with Genesis Potential Index(GPI) are examined to understand the frequency variation in cyclogenesis over the ARB and BOB. Over the ARB, thermodynamic factors such as mid-level moisture,surface latent heat flux and sensible heat flux, and dynamic parameters such as lower-level convergence and upper-level divergence, are favorable during the early and recent epochs but unfavorable during the middle epoch, and these results are found to be consistent with the observed epochal variability in the frequency of cyclogenesis. However, all these influential parameters are found to have decreased over the BOB during the entire 60-year period.  相似文献   

温度对平流层气溶胶光学常数及辐射特性的影响     

张建云  张国栋  许丽生 《成都信息工程学院学报》1993,(4)

本文阐述平流层气溶胶的光学常数在不同温度下取值时,用Mie散射理论对不同浓度的平流层气溶胶红外波段的辐射特性进行的计算和分析。分析结果表明:在卫星遥感中,由温度引起的平流层气溶胶光学常数的变化对某些红外波段的平流层气溶胶辐射特性的影响是不容忽视的。  相似文献   

The inhibition of marine nitrification by ocean disposal of carbon dioxide   总被引：1，自引：0，他引：1  

Huesemann MH  Skillman AD  Crecelius EA 《Marine pollution bulletin》2002,44(2):142-148

In an attempt to reduce the threat of global warming, it has been proposed that the rise of atmospheric carbon dioxide concentrations be reduced by the ocean disposal of CO2 from the flue gases of fossil fuel-fired power plants. The release of large amounts of CO2 into mid or deep ocean waters will result in large plumes of acidified seawater with pH values ranging from 6 to 8. In an effort to determine whether these CO2-induced pH changes have any effect on marine nitrification processes, surficial (euphotic zone) and deep (aphotic zone) seawater samples were sparged with CO2 for varying time durations to achieve a specified pH reduction, and the rate of microbial ammonia oxidation was measured spectrophotometrically as a function of pH using an inhibitor technique. For both seawater samples taken from either the euphotic or aphotic zone, the nitrification rates dropped drastically with decreasing pH. Relative to nitrification rates in the original seawater at pH 8, nitrification rates were reduced by ca. 50% at pH 7 and more than 90% at pH 6.5. Nitrification was essentially completely inhibited at pH 6. These findings suggest that the disposal of CO2 into mid or deep oceans will most likely result in a drastic reduction of ammonia oxidation rates within the pH plume and the concomitant accumulation of ammonia instead of nitrate. It is unlikely that ammonia will reach the high concentration levels at which marine aquatic organisms are known to be negatively affected. However, if the ammonia-rich seawater from inside the pH plume is upwelled into the euphotic zone, it is likely that changes in phytoplankton abundance and community structure will occur. Finally, the large-scale inhibition of nitrification and the subsequent reduction of nitrite and nitrate concentrations could also result in a decrease of denitrification rates which, in turn, could lead to the buildup of nitrogen and unpredictable eutrophication phenomena. Clearly, more research on the environmental effects of ocean disposal of CO2 is needed to determine whether the potential costs related to marine ecosystem disturbance and disruption can be justified in terms of the perceived benefits that may be achieved by temporarily delaying global warming.  相似文献   

近44 a中国冬夏气温变率及其对区域变暖性的影响   总被引：6，自引：2，他引：4  

吴胜安  江志红  屠其璞 《南京气象学院学报》2002,25(6):830-836

利用近44a中国85个测站冬夏季逐日平均、最高和最低气温序列,研究冬夏季温度季节变率及其时空演变特征,探讨其对区域变暖稳定性的影响。结果表明：冬季,除高原、西南、东北以外的中国大部分地区,温度的季节变率存在显著下降趋势,是近期变暖的稳定区,其中变暖最为稳定、显著的区域是西北、华北地区,东北北部虽变暖幅度很大,但稳定性最差;夏季,长江中下游及其江南地区温度变率存在显著上升趋势,20世纪70年代后年际变幅明显增大,表明该地区80年代降温的稳定性差。  相似文献   

气候变暖对黄河源区生态环境的影响   总被引：13，自引：2，他引：13  

曹文炳  万力  曾亦键  胡伏生  陈劲松 《地学前缘》2006,13(1):40-47

黄河源区位于多年冻土区,严酷寒冷的气候条件和冻土共同构建成一种特殊的冻结水环境,使地下水类型和水文地质结构均发生变化,与非冻土区有显著的差别,形成特殊的水文地质区。近几十年来,由于全球性气候温变暖,出现大面积冻土退化,以及过度放牧、鼠害加剧等原因,造成草场退化,沙漠化趋势日渐明显,严重地冲击着黄河河源区的水源养涵功能,导致黄河在源头段多次出现断流。通过水平衡计算,探讨了气候变暖对黄河源区多年冻土退化的影响,并阐述了冻结层上水环境变化和人类活动对生态环境的影响。  相似文献