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141.
Variability of soil moisture and its relationship with surface albedo and soil thermal parameters over the Loess Plateau 总被引:9,自引:0,他引:9
Data from July 2006 to June 2008 observed at SACOL(Semi-Arid Climate and Environment Observatory of Lanzhou University,35.946°N,104.137°E,elev.1961 m),a semi-arid site in Northwest China,are used to study seasonal variability of soil moisture,along with surface albedo and other soil thermal parameters, such as heat capacity,thermal conductivity and thermal diffusivity,and their relationships to soil moisture content.The results indicate that surface albedo decreases with increases in soil moisture content,s... 相似文献
142.
Mouhamadou Bamba Sylla E. Coppola L. Mariotti F. Giorgi P. M. Ruti A. Dell’Aquila X. Bi 《Climate Dynamics》2010,35(1):231-247
This study examines the ability of the latest version of the International Centre for Theoretical Physics (ICTP) regional
climate model (RegCM3) to reproduce seasonal mean climatologies, annual cycle and interannual variability over the entire
African continent and different climate subregions. The new European Center for Medium Range Weather Forecast (ECMWF) ERA-interim
reanalysis is used to provide initial and lateral boundary conditions for the RegCM3 simulation. Seasonal mean values of zonal
wind profile, temperature, precipitation and associated low level circulations are shown to be realistically simulated, although
the regional model still shows some deficiencies. The West Africa monsoon flow is somewhat overestimated and the Africa Easterly
Jet (AEJ) core intensity is underestimated. Despite these biases, there is a marked improvement in these simulated model variables
compared to previous applications of this model over Africa. The mean annual cycle of precipitation, including single and
multiple rainy seasons, is well captured over most African subregions, in some cases even improving the quality of the ERA-interim
reanalysis. Similarly, the observed precipitation interannual variability is well reproduced by the regional model over most
regions, mostly following, and sometimes improving, the quality of the ERA-interim reanalysis. It is assessed that the performance
of this model over the entire African domain is of sufficient quality for application to the study of climate change and climate
variability over the African continent. 相似文献
143.
144.
大气环流的年代际变化 II.GCM数值模拟研究 总被引:15,自引:2,他引:15
类似大气环流模式比较计划(AMIP)的数值模拟,将实际观测的海表水温(SST)资料引入模式进行40多年的数值积分,得到长时间的大气环流模拟结果。分析数值模拟结果发现,无论是大气中的主要涛动和遥相关型,还是重要大气环流系统都极为清楚地存在着年代际变化特征,包括10~20年准周期振荡和可能的30年以上的准周期振荡;而且上述主要环流系统的形势及其年代际变化大都与实际观测资料所给出的结果相一致。顺便分析中国东部气候的模拟结果,年代际变化特征(包括60年代的气候突变)也很清楚,并同大气环流变化配合十分合理。结果也表明,同研究季节和年际变化一样,大气环流模式(AGCM)数值模拟也是研究大气环流和气候年代际变化的有效方法。 相似文献
145.
利用常规气象观测资料和Micaps提供的相关资料,对2009年9月19—20日在河套地区发生的寒潮天气的环流形势及物理量进行分析。分析表明:在寒潮爆发前期,500hPa系统,蒙古西部的冷中心强度≥-32℃,且温度场滞后于高度场,为冷空气爆发南下提供了最基本条件;700hPa河套地区及上游≥16m.s-1的西北风急流基本形成,等温线与等高线交角≥45°且10个纬距内有4条及以上等温线的密集区;850hPa河套地区有≥16℃的暖中心,高空槽前后的西北风速≥18 m.s-1,温度线与高度线的夹角>45°;地面蒙古气旋的暖性性质为寒潮爆发的前期提供了有利的热力条件,地面冷锋后部冷高压轴线接近南北向,且冷高压中心强度≥1040hPa,3h变压≥3hPa。 相似文献
146.
147.
国内外气溶胶观测网络发展进展及相关科学计划 总被引:16,自引:6,他引:16
气溶胶是气候变化研究中的一个极大的不确定性因素,国内外在此方面开展了大量的观测和科学研究。本文首先对当前全球两大气溶胶观测网络,世界气象组织(WMO)的全球大气观测计划(GAW)和气溶胶自动观测网(AERONET)的组织、规模、设备、数据和气溶胶网络的规范作了介绍,并对近年来国际上的重大气溶胶科学计划的目标、实验方法、步骤作了介绍,说明观测网络的重要性。在此基础上对中国气溶胶观测网络的地位做了分析,并指出其在正在开展的中国气溶胶科学研究中的重要性。 相似文献
148.
149.
The major hydrological factors in lake-marsh systems are water level (depth), water surface area, and water volume. The key index for determining the lake-marsh pattern is water level, which leads to the variation of lake-marsh patterns under natural hydrological alternations. In addition, the vegetation structure also affects the lake-marsh pattern. With socioeconomic development and climate change, the ‘land use’ and ‘water use’ competitions appear more seriously between a lake-marsh system and its surrounding socioeconomic system, also inside the lake-marsh system. The possible optimal lake-marsh pattern could solve the contradictions mentioned above. As few studies focus on this issue, this study proposed an optimal lake-marsh pattern determination method with eco-hydrological management on relieving the land use and water use competitions. The optimal lake-marsh pattern determination method considers the protection objects (water depth demands), water supply (precipitation, surface water, and groundwater), and water demand (especially evapotranspiration) in the system at annual and monthly scales. Calculation and analysis were performed for the optimal pattern of the Wolonghu Wetlands as an example. The results mainly showed that the lake-marsh pattern of the Wolonghu Wetlands cannot be achieved on meeting both the maximum ecological services values and minimum water shortage amount under present natural condition. With artificial regulation measures, the possible optimal annual lake-marsh patterns can be obtained based on both ecological and hydrological objectives, with the area ratio of lake and marsh in the range of 0.650:0.350 and 0.726:0.274, the corresponding water level of lake body was of 86.85 to 87.0 m. This study could provide references for the Wolonghu Wetlands management, also for similar lake-marsh systems and other ecological systems. 相似文献
150.
In this paper, we give theBV photoelectric light curves of the Algol-type eclipsing binary EU Hydrae. We have analysed its period by means of the times of minima determined from this observation and the times of minima which other observers published. The period was found to gradually decrease with a change rate dP/dE = -3
.
d
29 × 10–10. The obtained light curves have been solved using Wilson-Devinney's synthetic light-curve program. The results demonstrate that EU Hydrae is a detached system, the secondary component fills the Roche-lobe, its mass ratio is 0.205. EU Hya may evolve to be a semidetached system in which the secondary component fills the Roche-lobe. 相似文献