共查询到20条相似文献，搜索用时 453 毫秒
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Internal heat flow from radioactive decay in Triton's interior along with absorbed thermal energy from Neptune total 5 to 20 percent of the insolation absorbed by Triton, thus comprising a significant fraction of Triton's surface energy balance. These additional energy inputs can raise Triton's surface temperature between approximately 0.5 and 1.5 K above that possible with absorbed sunlight alone, resulting in an increase of about a factor of approximately 1.5 to 2.5 in Triton's basal atmospheric pressure. If Triton's internal heat flow is concentrated in some areas, as is likely, local effects such as enhanced sublimation with subsequent modification of albedo could be quite large. Furthermore, indications of recent global albedo change on Triton suggest that Triton's surface temperature and pressure may not now be in steady state, further suggesting that atmospheric pressure on Triton was as much as ten times higher in the recent past. 相似文献
3.
Graham NE 《Science (New York, N.Y.)》1995,267(5198):666-671
Observations show that global average tropospheric temperatures have been rising during the past century, with the most recent portion of record showing a sharp rise since the mid-1970s. This study shows that the most recent portion of the global temperature record (1970 to 1992) can be closely reproduced by atmospheric models forced only with observed ocean surface temperatures. In agreement with a diverse suite of controversial observational evidence from the past 40 years, the upward trend in simulated tropospheric temperatures is caused by an enhancement of the tropical hydrologic cycle driven by increasing tropical ocean temperatures. Although it is possible that the observed behavior is due to natural climate variability, there is disquieting similarity between these model results, observed climate trends in recent decades, and the early expressions of the climatic response to increased atmospheric carbon dioxide in numerical simulations. 相似文献
4.
An atmospheric general circulation model was forced with observed interannual changes in the global sea surface temperatures (SSTs) for the period 1982 to 1993. The simulated seasonal surface air temperature patterns over land areas closely resemble the observed. Over most of the globe, the patterns also resemble those associated with EI Ni?o events and are also reproduced in simulations with weak warm tropical SSTs near the date line. An exception is northern Asia, where the mechanisms for the observed warming are unclear. The results suggest that enhanced air-sea interactions resulting from recent, more persistent warm oceanic conditions in the tropics contributed to the observed global warming trend during this period. 相似文献
5.
How much more rain will global warming bring? 总被引：2，自引：0，他引：2
Climate models and satellite observations both indicate that the total amount of water in the atmosphere will increase at a rate of 7% per kelvin of surface warming. However, the climate models predict that global precipitation will increase at a much slower rate of 1 to 3% per kelvin. A recent analysis of satellite observations does not support this prediction of a muted response of precipitation to global warming. Rather, the observations suggest that precipitation and total atmospheric water have increased at about the same rate over the past two decades. 相似文献
6.
[目的]分析近50年西北地区春季降水异常与Key海区海温异常的关系。[方法]利用近50年西北地区月平均降水资料和全球逐月海温格点资料,采用相关分析和SVD分析方法,探讨了赤道中东太平洋的海温异常对我国西北地区春季降水的影响。[结果]对于西北地区春季降水,选取前一年8~9月为海温关键时段,赤道中东太平洋海区为海温关键区,简称Key海区（125°~85°W,5°S~10°N）;相关分析表明,近50年西北地区春季降水与赤道中东太平洋海区,尤其是Key海区海温（前一年8~9月平均）有较好的正相关关系;SVD分析表明,西北地区春季降水异常具有同位相分布的特征,前一年8~9月赤道中东太平洋海温有较大的正相关系数,尤其在Key海区区有显著的耦合正相关。[结论]该研究为我国西北地区春季旱涝的气候预测提供了理论依据。 相似文献
7.
Rising mean sea level, it is proposed, is a significant indicator of global climate change. The principal factors that can have contributed to the observed increases of global mean sea level in recent decades are thermal expansion of the oceans and the discharge of polar ice sheets. Calculations indicate that thermal expansion cannot be the sole factor responsible for the observed rise in sea level over the last 40 years; significant discharges of polar ice must also be occurring. Global warming, due in some degree presumably to increasing atmospheric carbon dioxide, has been opposed by the extraction of heat necessary to melt the discharged ice. During the past 40 years more than 50,000 cubic kilometers of ice has been discharged and has melted, reducing the surface warming that might otherwise have occurred by as much as a factor of 2. The transfer of mass from the polar regions to a thin spherical shell covering all the oceans should have increased the earth's moment of inertia and correspondingly reduced the speed of rotation by about 1.5 parts in 10(8). This accounts for about three quarters of the observed fractional reduction in the earth's angular velocity since 1940. Monitoring of global mean sea level, ocean surface temperatures, and the earth's speed of rotation should be complemented by monitoring of the polar ice sheets, as is now possible by satellite altimetry. All parts of the puzzle need to be examined in order that a consistent picture emerge. 相似文献
8.
KW Oum MJ Lakin DO DeHaan T Brauers BJ Finlayson-Pitts 《Science (New York, N.Y.)》1998,279(5347):74-77
Halogen atoms from the reactions of sea-salt particles may play a significant role in the marine boundary layer. Reactions of sodium chloride, the major component of sea-salt particles, with nitrogen oxides generate chlorine atom precursors. However, recent studies suggest there is an additional source of chlorine in the marine troposphere. This study shows that molecular chlorine is generated from the photolysis of ozone in the presence of sea-salt particles above their deliquescence point; this process may also occur in the ocean surface layer. Given the global distribution of ozone, this process may provide a global source of chlorine. 相似文献
9.
Dynamics of recent climate change in the Arctic 总被引：2，自引：0，他引：2
The pattern of recent surface warming observed in the Arctic exhibits both polar amplification and a strong relation with trends in the Arctic Oscillation mode of atmospheric circulation. Paleoclimate analyses indicate that Arctic surface temperatures were higher during the 20th century than during the preceding few centuries and that polar amplification is a common feature of the past. Paleoclimate evidence for Holocene variations in the Arctic Oscillation is mixed. Current understanding of physical mechanisms controlling atmospheric dynamics suggests that anthropogenic influences could have forced the recent trend in the Arctic Oscillation, but simulations with global climate models do not agree. In most simulations, the trend in the Arctic Oscillation is much weaker than observed. In addition, the simulated warming tends to be largest in autumn over the Arctic Ocean, whereas observed warming appears to be largest in winter and spring over the continents. 相似文献
10.
生物质炭添加对农田温室气体净排放的影响综述 总被引：8，自引：1，他引：8
农田是温室气体的重要排放源,降低农田温室气体排放对减缓全球气候变化具有重要意义。生物质炭是生物质在缺氧条件下热解产生的固体物质,因其含碳量高、难于分解、比表面积大、疏松多孔等特性,已成为农田温室气体减排研究中人们关注和研究的热点。通过综述农田添加生物质炭对温室气体CO2、CH4和N2O排放的影响及其机制,以及对温室气体净排放[包括净增温潜势(NGWP)、温室气体净排放(NGHGE)和温室气体排放强度(GHGI)]的影响等方面的国内外研究进展,并结合目前国内外生物质炭的研究现状,提出了未来生物质炭在农田温室气体减排领域的研究方向,旨在为生物质炭在农田温室气体减排中的应用提供思路和参考。 相似文献
11.
Restoring Value to the World's Degraded Lands 总被引：4，自引：0，他引：4
Daily GC 《Science (New York, N.Y.)》1995,269(5222):350-354
Roughly 43 percent of Earth's terrestrial vegetated surface has diminished capacity to supply benefits to humanity because of recent, direct impacts of land use. This represents an approximately 10 percent reduction in potential direct instrumental value (PDIV), defined as the potential to yield direct benefits such as agricultural, forestry, industrial, and medicinal products. If present trends continue, the global loss of PDIV could reach approximately 20 percent by 2020. From a biophysical perspective, recovery of approximately 5 percent of PDIV is feasible over the next 25 years. Capitalizing on natural recovery mechanisms is urgently needed to prevent further irreversible degradation and to retain the multiple values of productive land. 相似文献
12.
KH Kjær SA Khan NJ Korsgaard J Wahr JL Bamber R Hurkmans M van den Broeke LH Timm KK Kjeldsen AA Bjørk NK Larsen LT Jørgensen A Færch-Jensen E Willerslev 《Science (New York, N.Y.)》2012,337(6094):569-573
Global warming is predicted to have a profound impact on the Greenland Ice Sheet and its contribution to global sea-level rise. Recent mass loss in the northwest of Greenland has been substantial. Using aerial photographs, we produced digital elevation models and extended the time record of recent observed marginal dynamic thinning back to the mid-1980s. We reveal two independent dynamic ice loss events on the northwestern Greenland Ice Sheet margin: from 1985 to 1993 and 2005 to 2010, which were separated by limited mass changes. Our results suggest that the ice mass changes in this sector were primarily caused by short-lived dynamic ice loss events rather than changes in the surface mass balance. This finding challenges predictions about the future response of the Greenland Ice Sheet to increasing global temperatures. 相似文献
13.
During the warm early Pliocene (approximately 4.5 to 3.0 million years ago), the most recent interval with a climate warmer than today, the eastern Pacific thermocline was deep and the average west-to-east sea surface temperature difference across the equatorial Pacific was only 1.5 +/- 0.9 degrees C, much like it is during a modern El Ni?o event. Thus, the modern strong sea surface temperature gradient across the equatorial Pacific is not a stable and permanent feature. Sustained El Ni?o-like conditions, including relatively weak zonal atmospheric (Walker) circulation, could be a consequence of, and play an important role in determining, global warmth. 相似文献
14.
Twentieth-Century Sea Surface Temperature Trends 总被引：4，自引：0，他引：4
MA Cane AC Clement A Kaplan Y Kushnir D Pozdnyakov R Seager SE Zebiak R Murtugudde 《Science (New York, N.Y.)》1997,275(5302):957-960
An analysis of historical sea surface temperatures provides evidence for global warming since 1900, in line with land-based analyses of global temperature trends, and also shows that over the same period, the eastern equatorial Pacific cooled and the zonal sea surface temperature gradient strengthened. Recent theoretical studies have predicted such a pattern as a response of the coupled ocean-atmosphere system to an exogenous heating of the tropical atmosphere. This pattern, however, is not reproduced by the complex ocean-atmosphere circulation models currently used to simulate the climatic response to increased greenhouse gases. Its presence is likely to lessen the mean 20th-century global temperature change in model simulations. 相似文献
15.
[目的]研究我国西北干旱区春季降水与全球海温的相关特征。[方法]利用1979～2008年GPCP全球逐月降水资料和NOAAERSST海温资料,采用相关分析和合成分析等方法,分析了西北干旱区30年来降水特征及其与全球海温的相关分布特征。[结果]1979～2008年西北干旱区春季降水量均呈波动增加;15°S～22°N、45°～105°E范围的印度洋海温对西北干旱区春季的降水具有持续性影响,可以作为一个预报西北干旱区春季降水的稳定因子。印度洋、孟加拉湾、阿拉伯海地区的海温偏高时,春季西北干旱区的降水有可能偏多;同时前期夏、秋、冬季赤道东太平洋附近的海温若偏高,对于次年西北干旱区春季降水很有利;阿拉伯海、中印度洋以及西太平洋地区的海温场是影响西北干旱区春季降水的关键因素。[结论]该研究为干旱区降水的预测预报提供理论依据。 相似文献
16.
Idso SB 《Science (New York, N.Y.)》1980,207(4438):1462-1463
The mean global increase in thermal radiation received at the surface of the earth as a consequence of a doubling of the atmospheric carbon dioxide content is calculated to be 2.28 watts per square meter. Multiplying this forcing function by the atmosphere's surface air temperature response function, which has recently been determined by three independent experimental analyses to have a mean global value of 0.113 K per watt per square meter, yields a value of 相似文献
17.
Freshwater methane emissions offset the continental carbon sink 总被引：7，自引：0，他引：7
Bastviken D Tranvik LJ Downing JA Crill PM Enrich-Prast A 《Science (New York, N.Y.)》2011,331(6013):50
Inland waters (lakes, reservoirs, streams, and rivers) are often substantial methane (CH(4)) sources in the terrestrial landscape. They are, however, not yet well integrated in global greenhouse gas (GHG) budgets. Data from 474 freshwater ecosystems and the most recent global water area estimates indicate that freshwaters emit at least 103 teragrams of CH(4) year(-1), corresponding to 0.65 petagrams of C as carbon dioxide (CO(2)) equivalents year(-1), offsetting 25% of the estimated land carbon sink. Thus, the continental GHG sink may be considerably overestimated, and freshwaters need to be recognized as important in the global carbon cycle. 相似文献
18.
Ocean salinities reveal strong global water cycle intensification during 1950 to 2000 总被引：3，自引：0，他引：3
Fundamental thermodynamics and climate models suggest that dry regions will become drier and wet regions will become wetter in response to warming. Efforts to detect this long-term response in sparse surface observations of rainfall and evaporation remain ambiguous. We show that ocean salinity patterns express an identifiable fingerprint of an intensifying water cycle. Our 50-year observed global surface salinity changes, combined with changes from global climate models, present robust evidence of an intensified global water cycle at a rate of 8 ± 5% per degree of surface warming. This rate is double the response projected by current-generation climate models and suggests that a substantial (16 to 24%) intensification of the global water cycle will occur in a future 2° to 3° warmer world. 相似文献
19.
Atmospheric carbon dioxide and aerosols: effects of large increases on global climate 总被引：1，自引：0，他引：1
Effects on the global temperature of large increases in carbon dioxide and aerosol densities in the atmosphere of Earth have been computed. It is found that, although the addition of carbon dioxide in the atmosphere does increase the surface temperature, the rate of temperature increase diminishes with increasing carbon dioxide in the atmosphere. For aerosols, however, the net effect of increase in density is to reduce the surface temperature of Earth. Because of the exponential dependence of the backscattering, the rate of temperature decrease is augmented with increasing aerosol content. An increase by only a factor of 4 in global aerosol background concentration may be sufficient to reduce the surface temperature by as much as 3.5 degrees K. If sustained over a period of several years, such a temperature decrease over the whole globe is believed to be sufficient to trigger an ice age. 相似文献
20.
Romanowicz B 《Science (New York, N.Y.)》1993,260(5116):1923-1926
For the past 80 years, the energy released in great strike-slip and thrust earthquakes has occurred in alternating cycles of 20 to 30 years. This pattern suggests that a global transfer mechanism from poloidal to toroidal components of tectonic plate motions is operating on time scales of several decades. The increase in seismic activity in California in recent years may be related to an acceleration of global strike-slip moment release, as regions of shear deformation mature after being reached by stresses that have propagated away from regions of great subduction decoupling earthquakes in the 1960s. 相似文献