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1.
区域气候模式对中国东部季风雨带演变的模拟 总被引：28，自引：6，他引：22
本文给出了应用区域气候模式对中国东部夏季雨带演变过程模拟的主要结果。模拟试验分别对正常季风年（1979）和湿季风年（1991）（均由观测场驱动）以及连续3年（全球大气环流模式驱动）的夏季降水场进行,并同观测场进行了比较。结果表明,模式基本上能抓住夏季雨带的主要位置和它的演变特征,与实况相比明显优于全球模式的结果。但模拟的雨带具体位置并不总是与观测值十分吻合,有些旬（或候）差别比较大,模拟的降水量与观测值的相关系数最大仅0.40左右。以上结果表明,为正确模拟东亚季风雨带的演变还需要对决定区域气候的主要物理过程在参数化方面作进一步的改进。 相似文献
2.
区域气候模式对我国中、东部夏季气候的数值模拟 总被引：9，自引：2，他引：9
利用高分辨率的区域气候模式RegCM3(ICTP,2004年)对1994、1997、1998年我国夏季(6～8月)气候进行了数值模拟试验,并对比分析了不同积云对流方案对降水场模拟结果的影响。结果表明:该模式能够较真实地描述出我国夏季温度场的主要高、低温中心及月际变化,但模拟的气温场偏低;选择不同的积云对流方案对降水的模拟结果影响很大,采用Grell积云对流方案模拟出的我国夏季降水场最接近观测场,较好地模拟出我国东部地区夏季主要雨带的大致位置及变化,但雨带的位置偏南、中心降水量值偏大;500 hPa位势高度场的模拟结果和实际观测场较为一致,但西风带的位置偏南,相应地副热带高压588位势什米线位置较观测场向东南偏移。 相似文献
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区域气候模式对东亚季风和中国降水的多年模拟与性能检验 总被引：43，自引：9，他引：43
利用高分辨率区域气候模式 (NCC/RegCM)对 1998～ 2 0 0 2年的东亚环流及中国区域降水进行了数值模拟。对模拟结果的检验表明 ,模式能较真实地模拟出东亚地区多年平均的月季环流特征、季风的年变化、中国各主要气候区温度、降水的季节变化及中国主要雨带的季节性进退。但模拟的气温场在夏季对流层中、低层海洋偏暖、陆地偏冷 ,由于温度场的这种系统性误差加大了夏季海、陆温差 ,导致模拟的东亚夏季风偏强 ,使夏季雨带位置向北偏移 ,从而使华北地区降水估计偏高 ,没能很好地反映最近 5a来中国降水呈南涝北旱的气候特征。模式中地形的作用及云 辐射参数化方案等的处理可能是模拟误差的主要来源 ,这也反映了模式对于准确模拟中国区域降水的长期异常分布还比较困难 ,今后应进一步改进模式的模拟能力。 相似文献
5.
RegCM3对山东夏季气候高分辨率模拟 总被引：1，自引：1，他引：0
利用区域气候模式RegCM3及NCEP/DOE再分析资料,对山东地区1985-2000年夏季区域气候变化进行了高分辨率(20 km)的数值模拟试验.通过对模拟结果和山东地区较密集的观测资料的比较分析,检验了模式在该地区的模拟能力.结果表明:(1)区域气候模式RegCM3能够合理地模拟出山东区域中高层的主要环流特征;(2)数值模拟能够合理再现山东地区16 a夏季平均降水南高北低和地面气温西高东低的主要分布特征.同时也能够合理地模拟出1990和1998年山东地区夏季强降水的主要特征,以及1992和1999年的干旱;(3) 模式结果较好地反映了1985-2000年16 a夏季山东地区降水和地面气温变率的主要特征. 相似文献
6.
MM5BATS对东亚夏季气候及其变化的模拟试验 总被引：5，自引：2，他引：3
将陆面过程模式BATS耦合到中尺度模式MM5V3中与另一区域气候模式RegCM2一起对1995—2000年夏季东亚的区域气候作了模拟试验,并与实际资料作了比较。模拟试验结果表明：(1)两个模式均能较合理地模拟出6年夏季平均的环流、温度和海平面气压等的变化,MM5BATS的模拟结果要略优于RegCM2的结果;(2)MM5BATS模式较合理地模拟出了6年夏季平均的降水分布,而RegCM2模式的模拟结果偏强;(3)MM5BATS模式较好地模拟出了1997年和1998年夏季环流场的变化,对降水的模拟也比较合理。RegCM2对1997年和1998年降水的模拟基本上都偏强。模拟试验结果还表明,在区域气候模拟中有必要采用更新的模式。 相似文献
7.
区域气候模式中径流计算方案的数值试验 总被引：10，自引：2，他引：10
采用由曼宁方程推导而来的动力波方程来改进陆面模式BATS中的径流计算方案，并将改进径流方案后的BA偈模式应用到区域气候模式RegCM2中。利用1998年6—8月T106资料做边界场，对改进后的区域气候模式在中国东部地区进行检验。模拟结果表明，改进后的方案在夏季6—8月内模拟的径流值达到80—500mm左右，较原方案模拟的径流量（30—80mm）更加接近径流实况（50—500mm），体现了径流的大尺度平流效应。取单站（武汉）的模拟结果与原模式进行比较，发现模拟场的平均气温与实况场的误差较原模式减小了0．66℃，几次明显的降水过程也有很好的模拟。文中还分析了气温、降水、土壤含水量、蒸发等量的模拟情况。 相似文献
8.
P-σ坐标系区域气候模式与GCM的嵌套试验 总被引：4，自引：4，他引：4
将P-σ坐标系区域气候模式与大气环流模式（GCM）单向嵌套，对我国1998年夏季长江流域严重洪涝进行模拟试验，并与GCM的模拟结果进行了比较。试验表明，嵌套的区域气候模式对降水场的模拟结果较GCM的结果有明显的改进，这是由于P-σ坐标系区域气候模式能够更真实地描述地形的动力和热力作用，因而能更准确地模拟青藏高原及其邻近地区的气压系统，在一定程度上弥补了低分辨率的GCM模拟在高原地区的不足，文中指出，与GCM嵌套的区域气候模式比GCM能够更有效地模拟区域气候的变化，尤其是对区域气候性特征比较明显的地区。 相似文献
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NCAR RegCM2对东亚区域气候的模拟试验 总被引：39，自引：3，他引：39
利用垂直、水平高分辨率的区域气候模式ＮＣＡＲＲｅｇＣＭ２（１９９６年５月最新版本）进行了１９９１年夏季（５～８月）东亚洪涝个例的区域气候数值模拟．与观测事实的比较表明，该模式能够较好地再现出该个例我国江淮流域—日本季风降水的主要时空特征和环流形势异常等．也指出了模拟结果的一些不足之处和今后的改进方向 相似文献
11.
Storms that occur at the Bay of Bengal (BoB) are of a bimodal pattern, which is different from that of the other sea areas. By using the NCEP, SST and JTWC data, the causes of the bimodal pattern storm activity of the BoB are diagnosed and analyzed in this paper. The result shows that the seasonal variation of general atmosphere circulation in East Asia has a regulating and controlling impact on the BoB storm activity, and the “bimodal period” of the storm activity corresponds exactly to the seasonal conversion period of atmospheric circulation. The minor wind speed of shear spring and autumn contributed to the storm, which was a crucial factor for the generation and occurrence of the “bimodal pattern” storm activity in the BoB. The analysis on sea surface temperature (SST) shows that the SSTs of all the year around in the BoB area meet the conditions required for the generation of tropical cyclones (TCs). However, the SSTs in the central area of the bay are higher than that of the surrounding areas in spring and autumn, which facilitates the occurrence of a “two-peak” storm activity pattern. The genesis potential index (GPI) quantifies and reflects the environmental conditions for the generation of the BoB storms. For GPI, the intense low-level vortex disturbance in the troposphere and high-humidity atmosphere are the sufficient conditions for storms, while large maximum wind velocity of the ground vortex radius and small vertical wind shear are the necessary conditions of storms. 相似文献
12.
The Fe(II)/Fe(III)-partition in cloudwater samples collected during two field campaigns is evaluated. It turned out that the simultaneous occurrence of complexing and reducing substances in the atmosphere and the cloud processing increase the solubility of iron compounds present in aerosol particles. A correlation between the concentration of iron(II) in the liquid phase and the intensity of the solar irradiation was observed for most of the cloudwater samples. This could be due to the fact that both the photochemical reduction of the iron(III) complexes and the photochemical reductive dissolution of iron(III)(hydr)oxides are depending on the pH-value. Iron(II) seems to be oxidised back to iron(III) preferably by hydrogen peroxide during the night. Positive correlations were received e.g. between the concentration of dissolved iron and the concentration of oxalate and between the percentage of iron(III) and the concentration of hydrogen peroxide. A negative correlation was found e.g. between the concentration of dissolved iron and the pH-value. The uncertainty of the whole process of sampling and analysis was investigated and the conformity of the results was satisfying considering the sometimes difficult conditions during a field campaign. 相似文献
13.
Projected changes in summer precipitation characteristics in China during the 21st century are assessed using the monthly precipitation outputs of the ensemble of three “best” models under the Special Report on Emissions Scenarios (SRES) A1B, A2, and B1 scenarios. The excellent reproducibility of the models both in spatial and temporal patterns for the precipitation in China makes the projected summer precipitation change more believable for the future 100 years. All the three scenarios experiments indicate a consistent enhancement of summer precipitation in China in the 21st century. However, the projected summer precipitation in China demonstrates large variability between sub-regions. The projected increase in precipitation in South China is significant and persistent, as well as in North China. Meanwhile, in the early period of the 21st century, the region of Northeast China is projected to be much drier than the present. But, this situation changes and the precipitation intensifies later, with a precipitation anomaly increase of 12.4%–20.4%
at the end of the 21st century. The region of the Xinjiang Province probably undergoes a drying trend in the future 100 years, and is projected to decrease by 1.7%–3.6% at the end of the 21st century. There is no significant long-term change of the projected summer precipitation in the lower reaches of the Yangtze River valley. A high level of agreement of the ensemble of the regional precipitation change in some parts of China is found across scenarios but smaller changes are projected for the B1 scenario and slightly larger changes for the A2 scenario. 相似文献
14.
Hainan, an island province of China in the northern South China Sea, experienced two sustained rainstorms in October2010, which were the most severe autumn rainstorms of the past 60 years. From August to October 2010, the most dominant signal of Hainan rainfall was the 10–20-day oscillation. This paper examines the roles of the 10–20-day oscillation in the convective activity and atmospheric circulation during the rainstorms of October 2010 over Hainan. During both rainstorms,Hainan was near the center of convective activity and under the influence of a lower-troposphere cyclonic circulation. The convective center was initiated in the west-central tropical Indian Ocean several days prior to the rainstorm in Hainan. The convective center first propagated eastward to the maritime continent, accompanied by the cyclonic circulation, and then moved northward to the northern South China Sea and South China, causing the rainstorms over Hainan. In addition, the westward propagation of convection from the tropical western Pacific to the southern South China Sea, as well as the propagation farther northward, intensified the convective activity over the northern South China Sea and South China during the first rainstorm. 相似文献
15.
Francisco P. J. Valero Thomas P. Ackerman Warren J. Y. Gore 《Journal of Atmospheric Chemistry》1989,9(1-3):225-244
The interaction of the Aretic winter aerosol (Arctic haze) with solar radiation produces changes in the radiation field that result in the enhancement of scattering and absorption processes which alter the energy balance and solar energy distribution in the Arctic atmosphere-surface system. During the second Arctic Gas and Aerosols Sampling Project (AGASP II) field experiment, we measured radiation parameters using the NOAA WP-3D research aircraft as a platform. State-of-the-art instrumentation was used to measure in situ the absorption of solar radiation by the Arctic atmosphere during severe haze events. Simultaneously with the absorption measurements, we determined optical depths, and total, direct, and scattered radiation fields. All optical measurements were made at spectral bands centered at 412, 500, 675, and 778 nm and with a bandpass of 10 nm. With this selection of spectral regions we concentrated on the measurement of the radiative effects of the aerosol excluding most of the contributions by the gaseous components of the atmosphere. An additional measurement performed during these experiments was the determination of total solar spectrum fluxes. The experimentally determined parameters were used to define an aerosol model that was employed to deduce the absorption by the aerosols over the full solar spectrum and to calculate atmospheric heating rate profiles. The analyses summarized above allowed us to deduce the magnitude of the change in some important parameters. For example, we found changes in instantaneous heating rate of up to about 0.6 K/day. Besides the increased absorption (30 to 40%) and scattering of radiation by the atmosphere, the haze reduces the surface absorption of solar energy by 6 to 10% and the effective planetary albedo over ice surfaces by 3 to 6%. The vertical distribution of the absorbing aerosol is inferred from the flux measurements. Values for the specific absorption of carbon are found to be around 6 m2/g for externally mixed aerosol and about 11.7 m2/g for internally mixed aerosol. A complete study of the radiative effects of the Arctic haze should include infrared measurements and calculations as well as physics of the ice, snow, and water surfaces. 相似文献
16.
欧亚冬季温带反气旋活动的气候特征 总被引：1，自引：0，他引：1
利用NCEP/NCAR再分析数据,通过判定和追踪温带反气旋的客观方法统计分析了1948-2013年欧亚地区冬季温带反气旋的生成、消亡、移动、生命史、强度等气候特征。结果表明,反气旋的主要源地位于蒙古高原、伊朗及其周边地区、地中海沿岸、中西伯利亚、波罗的海西北部、俄罗斯东北部等地,其中,蒙古高原和伊朗等地也是强反气旋最主要的源地。反气旋活动的大值分布区和反气旋生成的大值中心分布十分相似,主要活跃区对应低空平均经向温度梯度大值区和高空脊前。除源于蒙古高原和西伯利亚东北部的强、弱反气旋的移动距离差别不明显外,其他地区的反气旋移动距离与强度有密切关系。持续1-2 d的反气旋占总数的44.2%,而只有3.2%的反气旋生命史超过一周,且强反气旋比弱反气旋更易持续较长时间。 相似文献
17.
A one-dimensional, time-dependent cloud model with parameterized microphysics is used to investigate the processes which control the rainout and washout of soluble gases from warm, precipitating stratiform clouds. Calculations are presented simulating the distributions of soluble species within and below the cloud layer and in the precipitating raindrops as a function of time and species' solubility. Our calculations indicate that for species with low solubility, wet removal processes are relatively slow and thus do not significantly affect the species' gas-phase abundance. As a result, the removal of low-solubility species by rainout and washout is controlled by thermodynamic processes with the concentration of the species in cloud and rainwater largely determined by the species' solubility. For highly soluble species on the other hand, dissolution into cloud droplets and removal in rain is quite rapid and the abundance of highly soluble species within and below the cloud falls rapidly as soon as the precipitation begins. Because of this rapid decrease in concentration, we find that for highly soluble species: concentrations in cloud droplets near the cloud base can exceed that of raindrops by factors of 2 to 10; washout can dominate over rainout as a removal mechanism; and that, after an extended period of rainfall, the rate of removal becomes independent of the microphysical properties and rainfall rate of the cloud and is controlled by the rate of transport of material into the precipitating column by horizontal advection. 相似文献
18.
This study examines spatial and time evolutions of the principal constituents of the
Tunisian background aerosols under Sirocco wind circulations. Aerosols coming from the Sahara
Desert were found to be loaded with particulate matter, especially silicon. The aerosols were
shown to have varying geochemical behaviour along the ``South-North" displacement of the Saharan
plumes, depending on the wind flow characteristics, geomorphologic features and the nature of
soils swept by the wind. In the south and the center part of the country, the transfer of aerosol
constituents to the soil (by gravity and/or impaction) was probably predominated by localized
enrichment phenomena. The latter are reinforced by the effect of turbulent winds over bare soils,
wind wakes and probably selective disintegration, especially in the vicinity of the geomorphologic
features of central Tunisia. These relatively high features, extending over important distances,
appear to be of paramount importance for the phenomena of redistribution of aerosol constituents
even during periods without Sirocco wind circulations. In the northern section of the country,
aerosol constituent concentrations dropped to almost 50%, in spite of the abundance of localized
turbulent winds. This may be explained by the effect of forests and the relatively dense vegetation
cover, which clearly reinforces the transfer phenomena to the soil and the attenuate of dust
entrainment. 相似文献
19.
淮河流域水文极值预测模型研究 总被引：1，自引：0，他引：1
为探索气候变化影响下水文极值的非平稳性和预测方法,建立了水文极值非平稳广义极值（GEV）分布的统计预测模型。利用1952-2010年淮河上游流域累计面雨量和流量年最大值资料、同期500 hPa环流特征量资料以及17个CMIP5模式对环流特征量的模拟结果,筛选出对水文极值影响显著的年平均北半球极涡强度指数作为GEV分布参数的预测因子。分析了在RCP2.6、RCP4.5和RCP8.5情景下2006-2050年淮河上游流域水文极值对气候变化的响应。结果表明,10年以下与10年以上重现期的水文极值在非平稳过程中呈现前者下降而后者上升的相反变化趋势;多模型预测的集合平均在未来情景中均呈现上升趋势,情景排放量越大增幅越大,重现期越长增幅也越大。与极值的常态相比,极值的极端态更易受气候变化影响。 相似文献
20.
An assessment of the predictability of the East Asian Subtropical Westerly Jet based on TIGGE data 总被引：1，自引：0，他引：1
The predictability of the position, spatial coverage and intensity of the East Asian subtropical westerly jet(EASWJ) in the summers of 2010 to 2012 was examined for ensemble prediction systems(EPSs) from four representative TIGGE centers,including the ECMWF, the NCEP, the CMA, and the JMA. Results showed that each EPS predicted all EASWJ properties well, while the levels of skill of all EPSs declined as the lead time extended. Overall, improvements from the control to the ensemble mean forecasts for predicting the EASWJ were apparent. For the deterministic forecasts of all EPSs, the prediction of the average axis was better than the prediction of the spatial coverage and intensity of the EASWJ. ECMWF performed best, with a lead of approximately 0.5–1 day in predictability over the second-best EPS for all EASWJ properties throughout the forecast range. For probabilistic forecasts, differences in skills among the different EPSs were more evident in the earlier part of the forecast for the EASWJ axis and spatial coverage, while they departed obviously throughout the forecast range for the intensity. ECMWF led JMA by about 0.5–1 day for the EASWJ axis, and by about 1–2 days for the spatial coverage and intensity at almost all lead times. The largest lead of ECMWF over the relatively worse EPSs, such as NCEP and CMA, was approximately 3–4 days for all EASWJ properties. In summary, ECMWF showed the highest level of skill for predicting the EASWJ, followed by JMA. 相似文献