Hindcast Experiment of Extraseasonal Short-Term Summer Climate Prediction over China with RegCM3_IAP9L-AGCM   总被引：1，自引：0，他引：1       下载免费PDF全文

JU Lixi  LANG Xianmei 《Acta Meteorologica Sinica》2011,25(3):376-385

The regional climate model RegCM3 has been one-way nested into IAP9L-AGCM,the nine-level atmospheric general circulation model of the Institute of Atmospheric Physics,Chinese Academy of Sciences,to perform a 20-yr(1982-2001)hindcast experiment on extraseaonal short-term prediction of China summer climate.The nested prediction system is referred to as RegCM3_IAP9L-AGCM in this paper.The results show that hindcasted climate fields such as 500-hPa geopotential height,200-and 850-hPa zonal winds from RegCM3_IAP9L-AGCM have positive anomaly correlation coefficients (ACCs) with the observations,andare better than those from the stand-alone IAP9L-AGCM.Except for the 850-hPa wind field,the positive ACCs of the other two fields with observations both pass the 90% confidence level and display a zonal distribution.The results indicate that the positive correlation of summer precipitation anomaly percentage between the nested prediction system and observations covers most parts of China except for downstream of the Yangtze River and north of Northeast and Northwest China.The nested prediction system and the IAP9L-AGCM exhibit different hindcast skills over different regions of China,and the former demonstrates a higher skill over South China than the latter in predicting the summer precipitation.  相似文献   

云光学厚度对华北地区夏季边界层臭氧模拟影响评估     

姚石泉  王自发  李杰 《成都信息工程学院学报》2014,29(5)

为评估云光学厚度(CLDOPD)在空气质量数值模式中对边界层臭氧浓度的模拟影响,利用中国科学院大气物理研究所自主研发的嵌套网格空气质量预报模式系统(NAQPMS),对中国华北京津冀地区2013年6月夏季臭氧浓度进行模拟。结果表明:NAQPMS对极端对流性天气下的CLDOPD模拟偏低,结合观测数据对CLDOPD进行修正后,边界层臭氧浓度的模拟误差在一定程度上有所减小。此外,除极端性天气外模式对高CLDOPD值情况下的边界层臭氧浓度的模拟能力要优于低值情况。  相似文献   

Using adaptively coupled models and high-performance computing for enabling the computability of dust storm forecasting     

Qunying Huang  Karl Benedict  Abdelmounaam Rezgui  Jibo Xie  Jizhe Xia 《International journal of geographical information science》2013,27(4):765-784

Forecasting dust storms for large geographical areas with high resolution poses great challenges for scientific and computational research. Limitations of computing power and the scalability of parallel systems preclude an immediate solution to such challenges. This article reports our research on using adaptively coupled models to resolve the computational challenges and enable the computability of dust storm forecasting by dividing the large geographical domain into multiple subdomains based on spatiotemporal distributions of the dust storm. A dust storm model (Eta-8bin) performs a quick forecasting with low resolution (22 km) to identify potential hotspots with high dust concentration. A finer model, non-hydrostatic mesoscale model (NMM-dust) performs high-resolution (3 km) forecasting over the much smaller hotspots in parallel to reduce computational requirements and computing time. We also adopted spatiotemporal principles among computing resources and subdomains to optimize parallel systems and improve the performance of high-resolution NMM-dust model. This research enabled the computability of high-resolution, large-area dust storm forecasting using the adaptively coupled execution of the two models Eta-8bin and NMM-dust.  相似文献   

Surface and subsurface water contributions to streamflow from a mesoscale watershed in complex mountain terrain          下载免费PDF全文

Qinghuan Zhang  John F. Knowles  Rebecca T. Barnes  Rory M. Cowie  Nathan Rock  Mark W. Williams 《水文研究》2018,32(7):954-967

An understanding of surface and subsurface water contributions to streamflow is essential for accurate predictions of water supply from mountain watersheds that often serve as water towers for downstream communities. As such, this study used the end‐member mixing analysis technique to investigate source water contributions and hydrologic flow paths of the 264 km² Boulder Creek Watershed, which drains the Colorado Front Range, USA. Four conservative hydrochemical tracers were used to describe this watershed as a 3 end‐member system, and tracer concentration reconstruction suggested that the application of end‐member mixing analysis was robust. On average from 2009 to 2011, snowmelt and rainwater from the subalpine zone and groundwater sampled from the upper montane zone contributed 54%, 22%, and 24% of the annual streamflow, respectively. These values demonstrate increased rainwater and decreased snow water contributions to streamflow relative to area‐weighted mean values derived from previous work at the headwater scale. Young water (2.3 ± 0.8 months) fractions of streamflow decreased from 18–22% in the alpine catchment to 8–10% in the lower elevation catchments and the watershed outlet with implications for subsurface storage and hydrological connectivity. These results contribute to a process‐based understanding of the seasonal source water composition of a mesoscale watershed that can be used to extrapolate headwater streamflow generation predictions to larger spatial scales.  相似文献   

中国旅游经济区域差异的空间分析   总被引：18，自引：3，他引：15  

汪德根  陈田 《地理科学》2011,31(5):528-536

利用二阶段嵌套泰尔系数分解方法,揭示2000~2008年中国入境旅游经济和国内旅游经济区域发展的省内地(市)间差异、省间差异、地带差异变化特征及其对全国总体差异的贡献率,并以省内地(市)间差异为视角,分析中国旅游经济区域差异的空间格局。研究结果表明:① 中国入境旅游和国内旅游的总体差异呈缩小趋势,且国内旅游的区域差异明显小于入境旅游的区域差异。② 省内差异对全国旅游经济总体差异变化的影响比地带间差异和省间差异对其影响更为显著,已成为全国旅游经济总体差异的重要构成部分;东部地带省间差异明显,对总体差异影响显著,而中西部各省份间旅游业发展相对均衡。③ 东部地带部分旅游业发达省份的省内差异明显,对总体差异的贡献率较高;中西部地带省内差异明显的省份较多,旅游发展空间格局表现为"双核"模式或"单核"模式,但因中西部省份的旅游经济占全国的比重普遍较低,因此中西部省内差异对全国整体差异的贡献率并不高。④ 相关分析得出,旅游资源禀赋、交通可达性、经济发展水平是影响中国旅游经济区域差异空间格局的主要因素。  相似文献   

中等城市居民购物行为时空决策过程及影响因素——以安徽省芜湖市为例   总被引：5，自引：1，他引：4  

焦华富  韩会然 《地理学报》2013,68(6):750-761

购物决策过程是居民根据自身需求进行购物信息搜寻、购物目的地选择等方面的完整过程,是居民购物行为发生与实施的前提和基础,已经成为城市地理学研究的热点之一。本文利用2011 年芜湖市居民购物行为调查问卷数据,通过构建居民购物出行的嵌套Logit 模型,从购物出行模式决策、购物初始时间决策、购物目的地决策、购物出行交通方式决策等四个层面对芜湖市居民购物行为的决策过程及影响因素进行了探讨。结果表明:① 居民属性特征对购物出行模式决策具有显著影响,男性居民选择单纯购物出行的概率较大,而女性居民、有家人陪伴的居民更倾向多目的出行;在中心城区居住及出行距离远的居民偏好中午进行多目的购物概率较大,出行距离集中在1~2 km的范围内,而近郊区居民则避开下班高峰期进行购物,倾向选择2~5 km的购物空间范围;② 具有私家车的男性居民在晚上进行购物的概率比较大,其出行概率是上午的2.94 倍,更加偏好远距离出行;居民上下班途中购物大多发生在下班时间,偏好5~8 km范围的远距离;有朋友陪伴的居民更倾向上午依赖公共交通进行远距离出行;③ 以家为购物出发地点的居民的购物更倾向19:00 之后并且偏好远距离出行,公交车依然是芜湖市居民购物出行的主要载体。  相似文献   

不规则区域海浪嵌套模式设计及其应用实例     

沈华杰  尹训强  江兴杰  孙盟  杨永增  汪一航 《台湾海峡》2013,32(3)

本研究针对第三代MASNUM海浪模式的并行设计特点,设计实现了并行化不规则嵌套计算,从而提高了海浪模式嵌套模拟的灵活性和时效性.选取浙江舟山、宁波附近海域,利用201 1年的NCEP再分析风场作为强迫,采用大、中、小网格并利用该嵌套模式进行了三重嵌套应用.其中大、中区域实验均采用规则矩形方式设置开边界,大区域的模拟结果为中区域嵌套实验提供开边界条件,同时中区域嵌套输出小区域嵌套实验在不规则开边界上的边界条件.中区域的实验结果与卫星观测资料的对比表明:嵌套实验比无嵌套实验的误差小30％左右,二者在开边界附近的有效波高差异较大,达到0.5m以上.8月份中区域的无嵌套实验所得有效波高平均为0.7m,最大值为3.6m,嵌套实验结果则分别为1.0、7.1m,后者更接近以往观测资料所显示的平均波高1.5～2.0 m和最大波高5.0 ～10.0 m的结果,表明该常规嵌套方式的可行性.小区域实验也包含嵌套和无嵌套2个实验,开边界均采用不规则形状.实验结果表明:在5～8月期间,嵌套实验的波向与无嵌套的波向差异较明显,主要表现为外海传入;在6～7月份,嵌套实验与无嵌套实验有效波高的差值达1.0m以上;嵌套实验的周期普遍大于无嵌套的模拟结果,其最大差异为8 s.上述实验结果表明,该嵌套模式可实现规则开边界区域和不规则区域的嵌套模拟,可应用于复杂近岸区域的海浪数值模拟和预报,有效提高对关注区域海浪的模拟能力.  相似文献   

Spatial scale impact on daily surface water and sediment fluxes in Thukela river,South Africa     

《Physics and Chemistry of the Earth》2016

The on- and off-site effects of soil erosion in many environments are well known, but there is still limited understanding of the soil loss fluxes in downstream direction due, among other factors, to scarce and poor quality. A four year study to (i) evaluate water and sediment fluxes at different spatio-temporal scales and (ii) interpret the results in terms of processes involved and the controlling factors, was conducted in Thukela basin, South Africa. Five hierarchically nested catchments; namely microcatchment (0.23 km²), subcatchment (1.20 km²), catchment (9.75 km²), sub-basin (253 km²) and basin (29,038 km²), were used in addition to fifteen (1 m²) microplots and ten (10 m²) plots on five locations within the microcatchment. The results showed 19% decrease of unit-area runoff (q) from 3.1 L m⁻² day⁻¹ at microplot to 2.5 L m⁻² day⁻¹ at plot scale followed by steeper (56%) decrease at microcatchment scale. The q decreased in downstream direction to very low level (q ≤ 0.26 L m⁻² day⁻¹). The changes in q were accompanied by initial 1% increase of soil loss (SL) from 18.8 g m⁻² day⁻¹ at microplot to 19.1 g m⁻² day⁻¹ at plot scale. The SL also decreased sharply (by 39 fold) to 0.50 g m⁻² day⁻¹ at microcatchment scale, followed by further decrease in downstream direction. The decrease of q with spatial scale was attributed to infiltration losses, while initial increase of SL signified greater competence of sheet than splash erosion. The decrease of SL beyond the plot scale was attributed to redistribution of the soil on the hillslope and deposition on the stream channel upstream of the microcatchment outlet. Therefore, erosion control strategies focussing on the recovery of vegetation on the slope and stabilisation of gullies are recommended.  相似文献   

敦煌绿洲夏季边界层特征的数值模拟   总被引：16，自引：14，他引：2  

吕世华  罗斯琼 《高原气象》2004,23(2):147-154

使用美国NCAR新版MM5V3．6非静力平衡模式,采用三重嵌套方法,模拟研究了沙漠绿洲的环流及边界层特征。并且与无绿洲试验进行了比较。结果表明：沙漠中的绿洲在夏季是一个冷源,地面感热通量和潜热通量与周围的沙漠地区存在较大差异。在绿洲区,感热通量小,潜热通量大;在沙漠区,感热通量大,潜热通量小。绿洲边界层顶低,沙漠边界层顶高。绿洲可以改变沙漠地区的大气稳定度,使得原来大气层结不稳定的沙漠地区出现较稳定的大气层结。沙漠绿洲改变了原有沙漠地区的环流结构及温、湿场的分布,使得在绿洲上空大气下沉,沙漠上空大气上升,从而产生了绿洲上空大气干冷,沙漠上空大气暖湿的边界特征。绿洲边缘的沙漠形成的较大的湿气柱围绕着绿洲,起到了保护绿洲的作用。沙漠绿洲低空呈现辐散气流,使得绿洲上风方的沙漠地区风速减小,绿洲下风方的沙漠地区风速增大。  相似文献   

Multiscale sources of spatial variation in soil. III. Improved methods for fitting the nested model to one-dimensional semivariograms     

C. C. Taylor  P. A. Burrough 《Mathematical Geology》1986,18(8):811-821

The previous paper in this series presented a one-dimensional stochastic nested model to account for superimposed sources of soil variation at various scales. This paper shows how the nested model can be fitted to experimental data using weighted or generalized least-squares methods that account for correlations between consecutive terms that had previously been neglected. This paper also presents a method of estimating effective degrees of freedom for each sampling interval and thus for estimating 90% confidence limits for the semivariogram of the nested model.  相似文献