共查询到20条相似文献，搜索用时 15 毫秒
1.
Jianguo LIU Zong-Liang YANG Binghao JIA Longhuan WANG Ping WANG Zhenghui XIE Chunxiang SHI 《大气科学进展》2023,40(2):235-250
In order to compare the impacts of the choice of land surface model(LSM) parameterization schemes, meteorological forcing, and land surface parameters on land surface hydrological simulations, and explore to what extent the quality can be improved, a series of experiments with different LSMs, forcing datasets, and parameter datasets concerning soil texture and land cover were conducted. Six simulations are run for the Chinese mainland on 0.1° × 0.1° grids from 1979 to 2008, and the simulated mon... 相似文献
2.
This work introduced a method to study river flow variability in response to climate change by using remote sensing precipitation data, downscaled climate model outputs with bias corrections, and a land surface model. A meteorological forcing dataset representing future climate was constructed via the delta change method in which the modeled change was added to the present-day conditions. The delta change was conducted at a fine spatial and temporal scale to contain the signals of weather events, which exhibit substantial responses to climate change. An empirical transformation technique was further applied to the constructed forcing to ensure a realistic range. The meteorological forcing was then used to drive the land surface model to simulate the future river flow. The results show that preserving fine-scale processes in response to climate change is a necessity to assess climatic impacts on the variability of river flow events. 相似文献
3.
地表作为大气模块的下垫面,为大气模块提供边界条件,地形对于模式结果的准确性起到至关重要的作用。现有的陆面过程模式在陆面同一网格内的次网格单元采用相同的大气强迫量,没有考虑次网格地形对网格内大气强迫量的影响,这关系到模式对气象要素和陆气交换量的模拟水平。本文在陆面模式NOAH处理次网格单元的同时,将输入的大气强迫量根据其与地形高度的关系进行修订,提出新的次网格地形的参数化方案,并引入到WRF（Weather Research and Forecasting）模式中进行数值试验,通过3组数值模拟试验,与未改进的方案和细网格方案分析比较,探讨新参数化方案对WRF 模式模拟结果的影响。结果表明:地形越复杂区域,次网格地形的影响越大。本文引入的新陆面次网格地形方案对天山山脉和昆仑山脉以及青藏高原南部的地表气温的模拟有较大改善,模拟的地表气温在大范围区域内都更贴近细网格方案。虽然新陆面次网格地形方案和细网格试验都对温度的模拟结果都有改善,但新陆面次网格地形方案对降水的模拟改善甚微,而细网格试验对降水模拟却有改进,这是由于细网格试验在陆面和大气网格都进行了细化,而新陆面次网格地形方案只考虑了陆面次网格的影响。具体来说,新陆面次网格地形方案对温度的模拟结果改进是通过改变地表向上长波和地表感热实现的。而细网格试验由于同时细化了大气和陆面的空间网格,对降水和温模拟的改进是通过综合改变地表能量平衡实现的。 相似文献
4.
5.
Identifying Nonstationarity in Turbulence Series 总被引：1，自引：1，他引：0
Edgar L Andreas Cathleen A. Geiger George Treviño Kerry J. Claffey 《Boundary-Layer Meteorology》2008,127(1):37-56
Because of rapid forcing by varying cloud and sky conditions, turbulence time series collected in the atmospheric surface
layer over land may often be nonstationary. The meteorological community, however, has no consensus definition of what nonstationarity
is and, thus, no consensus method for how to identify it. This study, therefore, adopts definitions for first-order and second-order
stationarity taken from the time series analysis literature and implements new analysis techniques and probabilistic tests
to quantify first-order and second-order nonstationarity. First-order nonstationarity manifests as a change in the series
mean; second-order nonstationarity, as a change in the variance. The analysis identifies nonstationarity in surface-level
turbulent temperature and water vapour series collected during two sample days with solar forcing influenced by cirrus and
cirrostratus clouds, but that nonstationarity is not as severe as expected despite the rapid thermal forcing by these clouds.
On the other hand, even with negligible cloud forcing, both sample days exhibited severe nonstationarity at night. 相似文献
6.
Relative Influence of Urban And Orographic Effects for Low Wind Conditions in the Paris Area 总被引：1，自引：0，他引：1
The relative roles of land-use and orography on the meteorological fields in the Paris area are studied by means of numerical simulations of two Special Observing Periods (SOP), of the ECLAP experiment. Sensitivity experiments have been performed with flat orography to investigate the strength of the urban effects, and with a uniform land-use surface to replace the surface heterogeneities, to isolate the orographic forcing. Comparisons of the simulated fields with a reference simulation including all forcing are analysed. It is found that during these two SOP of spring-time conditions, despite the low terrain elevation, the orographic effect is the main forcing of the dynamic field but that although the land use is the dominant factor reproducing the thermal evolution of the boundary layer, the orography alone also plays a role in the temperature pattern with slope flows in and out of the Paris basin. 相似文献
7.
地形作为大气的外部强迫,其动力和热力作用对波动结构演变及极端天气出现都有不能忽视的作用。本文通过数值求解考虑地形强迫的β平面正压准地转位势涡度方程,探讨了地形强迫作用对大气长波调整的可能影响,结果表明:同非线性作用和纬向非均匀基流作用一样,无基流情形下具有纬向差异的地形分布影响了大气长波结构的演变,也能强迫出大气长波调整现象。大气长波调整依赖于地形的高度和地形分布,地形越高,长波越容易出现波数的调整;地形波数越大,即地形结构复杂,越不易出现波数变化。大气长波调整还与纬度有关,纬度越高,β越小,地形强迫作用越突出,长波调整容易出现;反之,低纬度以β效应为主的线性波动不易出现波数调整。大气长波调整对波动初始波动的振幅不敏感,但依赖于波动的初始结构。此外,有基流作用时,地形强迫还是诱发定常波的重要因素,且定常波流场结构依赖于地形高度分布,与波动初始结构无关。 相似文献
8.
The impact of asymmetric thermal forcing associated with land–sea distribution on interdecadal variation in large-scale circulation and blocking was investigated using observations and the coupled model intercomparison project outputs. A land–sea index (LSI) was defined to measure asymmetric zonal thermal forcing; the index changed from a negative to a positive anomaly in the 1980s. In the positive phase of the LSI, the 500 hPa geopotential height decreased in the polar regions and increased in the mid-latitudes. The tropospheric planetary wave activity also became weaker and exerted less easterly forcing on the westerly wind. These circulation changes were favorable for westerly wind acceleration and reduced blocking. In the Atlantic, the duration of blocking decreased by 38 % during the positive LSI phase compared with that during the negative phase; in Europe, the number of blocking persisting for longer than 10 days during the positive LSI phase was only half of the number during the negative phase. The observed surface air temperature anomaly followed a distinctive “cold ocean/warm land” (COWL) pattern, which provided an environment that reduced, or destroyed, the resonance forcing of topography and was unfavorable for the development and persistence of blocking. In turn, the responses of the westerly and blocking could further enhance continental warming, which would strengthen the “cold ocean/warm land” pattern. This positive feedback amplified regional warming in the context of overall global warming. 相似文献
9.
W. Gorter J. H. van Angelen J. T. M. Lenaerts M. R. van den Broeke 《Climate Dynamics》2014,42(5-6):1595-1611
The present and twenty-first century near-surface wind climate of Greenland is presented using output from the regional atmospheric climate model RACMO2. The modelled wind variability and wind distribution compare favourably to observations from three automatic weather stations in the ablation zone of southwest Greenland. The Weibull shape parameter is used to classify the wind climate. High values (κ > 4) are found in northern Greenland, indicative of uniform winds and a dominant katabatic forcing, while lower values (κ < 3) are found over the ocean and southern Greenland, where the synoptic forcing dominates. Very high values of the shape parameter are found over concave topography where confluence strengthens the katabatic circulation, while very low values are found in a narrow band along the coast due to barrier winds. To simulate the future (2081–2098) wind climate RACMO2 was forced with the HadGEM2-ES general circulation model using a scenario of mid-range radiative forcing of +4.5 W m?2 by 2100. For the future simulated climate, the near-surface potential temperature deficit reduces in all seasons in regions where the surface temperature is below the freezing point, indicating a reduction in strength of the near-surface temperature inversion layer. This leads to a wind speed reduction over the central ice sheet where katabatic forcing dominates, and a wind speed increase over steep coastal topography due to counteracting effects of thermal and katabatic forcing. Thermally forced winds over the seasonally sea ice covered region of the Greenland Sea are reduced by up to 2.5 m s?1. 相似文献
10.
冬季北半球地形与定常热源强迫所产生的定常行星波及其动量通量、热量通量的计算 总被引：2，自引：0，他引：2
本文应用一个包括Rayleigh摩擦、牛顿冷却、水平涡旋热量扩散、定常、准地转、34层球坐标模式来研究冬季北半球地形与定常热源强迫所产生的定常行星波。 本文计算了强迫所产生的定常行星波引起的动量通量与热量通量。计算结果与观测结果比较一致。 计算结果表明:最大向北的动量通量与热量通量位于平流层。 相似文献
11.
We present an analysis of data from a nearly 1-year measurement campaign performed at Høvsøre, Denmark, a coastal farmland area where the terrain is flat. Within the easterly sector upstream of the site, the terrain is nearly homogenous. This topography and conditions provide a good basis for the analysis of vertical wind-speed profiles under a wide range of atmospheric stability, turbulence, and forcing conditions. One of the objectives of the campaign was to serve as a benchmark for flow over flat terrain models. The observations consist of combined wind lidar and sonic anemometer measurements at a meteorological mast. The sonic measurements cover the first 100 m and the wind lidar measures above 100 m every 50 m in the vertical. Results of the analysis of observations of the horizontal wind-speed components in the range 10–1200 m and surface turbulence fluxes are illustrated in detail, combined with forcing conditions derived from mesoscale model simulations. Ten different cases are presented. The observed wind profiles approach well the simulated gradient and geostrophic winds close to the simulated boundary-layer height during both barotropic and baroclinic conditions, respectively, except for a low-level jet case, as expected. The simulated winds are also presented for completeness and show good agreement with the measurements, generally underpredicting the turning of the wind in both barotropic and baroclinic cases. 相似文献
12.
本文总结了“青藏高原大地形及西太平洋暖池势力强迫对东亚及全球气候变化的影响”专题五年来的主要研究工作。其中包括青世故高原东部大气热源的时间演变特征,夏半年高原热源异常对我国降水和北半球环流的影响;西沙海温变化特征及其与我南方降水的关系,北太平洋海温主因子特征及其与华南前汛期降水的变化。 相似文献
13.
Magdalena Falco Andrea F. Carril Laurent Z. X. Li Carlos Cabrelli Claudio G. Men&#;ndez 《Climate Dynamics》2020,54(3):1553-1569
This paper aims to identify those regions within the South American continent where the Regional Climate Models (RCMs) have the potential to add value (PAV) compared to their coarser-resolution global forcing. For this, we used a spatial-scale filtering method based on the wavelet theory to distinguish the regional climatic signal present in atmospheric surface fields from observed data (CPC and TRMM) and 6 RCM simulations belonging to the CORDEX Project. The wavelet used for filtering was Haar wavelet, but a comparative analysis with Daubechies 4 wavelet indicated that meteorological fields or regional indices were not very sensitive to the wavelet selected. Once the longer wavelengths were filtered, we focused on analyzing the spatial variability of extreme rainfall and the spatiotemporal variability of maximum and minimum surface air temperature on a daily basis. The results obtained suggest essential differences in the spatial distribution of the small-scale signal of extreme precipitation between TRMM and regional models, together with a large dispersion between models. While TRMM and CPC register a large signal throughout the continent, the RCMs place it over the Andes Cordillera and some over tropical South America. PAV signal for surface air temperature was found over the Andes Cordillera and the Brazilian Highlands, which are regions characterized by complex topography, and also on the coasts of the continent. The signal came specially from the small-scale stationary component. The transient part is much smaller than the stationary one, except over la Plata Basin where they are of the same order of magnitude. Also, the RCMs and CPC showed a large spread between them in representing this transient variability. The results confirm that RCMs have the potential to add value in the representation of extreme precipitation and the mean surface temperature in South America. However, this condition is not applicable throughout the whole continent but is particularly relevant in those terrestrial regions where the surface forcing is strong, such as the Andes Cordillera or the coasts of the continent. 相似文献
14.
Tao Li Xiaogu Zheng Yongjiu Dai Chi Yang Zhuoqi Chen Shupeng Zhang Guocan Wu Zhonglei Wang Chengcheng Huang Yan Shen Rongwei Liao 《大气科学进展》2014,31(5):1127-1135
As part of a joint effort to construct an atmospheric forcing dataset for mainland China with high spatiotemporal reso- lution, a new approach is proposed to construct gridded near-surface temperature, relative humidity, wind speed and surface pressure with a resolution of 1 km× 1 km. The approach comprises two steps： （1） fit a partial thin-plate smoothing spline with orography and reanalysis data as explanatory variables to ground-based observations for estimating a trend surface; （2） apply a simple kriging procedure to the residual for trend surface correction. The proposed approach is applied to observations collected at approximately 700 stations over mainland China. The generated forcing fields are compared with the corresponding components of the National Centers for Environmental Predic- tion （NCEP） Climate Forecast System Reanalysis dataset and the Princeton meteorological forcing dataset. The comparison shows that, both within the station network and within the resolutions of the two gridded datasets, the interpolation errors of the proposed approach are markedly smaller than the two gridded datasets. 相似文献
15.
根据2017、2019年7月塔克拉玛干沙漠腹地GPS探空和地面观测数据,利用位温廓线法等方法,对比分析了沙漠腹地夏季晴天和沙尘暴天气大气边界层结构变化特征。结果表明：晴天和沙尘暴天气大气边界层结构特征显著不同。晴天大气边界层各气象要素垂直分布较为均一,白天对流边界层深厚,高度接近5 km,夜间稳定边界层一般在500 m左右。沙尘暴天气边界层内位温和比湿垂直变化较小,风速较大,可达24.0 m/s,其白天对流边界层在1.5 km左右,夜间稳定边界层在1 km左右。晴天辐射强烈,地表升温迅速,湍流旺盛,是形成晴天深厚对流边界层的主要因素。大尺度天气系统冷平流的动力条件,以及云和沙尘减弱了到达地表的辐射强度是形成沙尘暴天气独特的大气边界层结构的主要因素。 相似文献
16.
利用2004年5月以来超声雪深传感器SR-50在青藏高原唐古拉综合监测场获取的实时积雪资料和相关气象数据,评估了SR-50在青藏高原积雪监测中的性能和作用,并对青藏高原腹地多年冻土区积雪变化特征进行初步分析。结果表明:超声雪深传感器SR-50对不同时间尺度的地表积雪过程均有较好的监测能力。监测数据清晰地显示唐古拉地区地表积雪深度在夜间相对稳定、在日间迅速降低的特点。唐古拉地区平均年积雪日数为82 d,各月均有地表积雪出现,但夏季的地表积雪较少且持续时间很短。该地区地表积雪总体上呈厚度较薄、消融较快、持续时间较短的特点。2005—2008年该地区瞬时最大积雪深度为22 cm,日平均积雪深度小于5 cm日数占总积雪日数的71.58%。 相似文献
17.
Christos H. Halios Costas G. Helmis Helena A. Flocas Stephan Nyeki Dimosthenis N. Assimakopoulos 《Meteorology and Atmospheric Physics》2012,118(3-4):107-115
Synoptic climatology relates the atmospheric circulation with the surface environment. The aim of this study is to examine the variability of the surface meteorological patterns, which are developing under different synoptic scale categories over a suburban area with complex topography. Multivariate Data Analysis techniques were performed to a data set with surface meteorological elements. Three principal components related to the thermodynamic status of the surface environment and the two components of the wind speed were found. The variability of the surface flows was related with atmospheric circulation categories by applying Correspondence Analysis. Similar surface thermodynamic fields develop under cyclonic categories, which are contrasted with the anti-cyclonic category. A strong, steady wind flow characterized by high shear values develops under the cyclonic Closed Low and the anticyclonic H–L categories, in contrast to the variable weak flow under the anticyclonic Open Anticyclone category. 相似文献
18.
A Model to Predict Surface Temperatures 总被引：3，自引：0，他引：3
M.J. Best 《Boundary-Layer Meteorology》1998,88(2):279-306
A model to predict the surface temperature of a variety of surfaces is described. The model solves the surface energy balance equation iteratively, using only standard meteorological data. Since surface and soil temperature information is not required for initialisation, the model is portable and, in theory, could be used for any surface and location. It is shown that, in order to obtain the correct cooling rates for vegetation during the night, the direct influence of the ground flux must be removed from the energy balance equation for the layer of vegetation. A scheme that couples a vegetation canopy to the ground solely by radiation is described, giving satisfactory cooling rates when compared with observations. Observations from a field site at Cardington, near Bedford, UK, are used to test the accuracy of the model for road and grass surfaces. When compared against these data, the model predicts surface temperatures with a root mean square error of about 1 °C for the road and 2 °C for the grass. Data from other sources not only give similar results to the Cardington data, but also demonstrate that the model can reproduce the characteristics of wet and partially dry soils and also dry desert sand. A study of the sensitivity of the model to errors in the forcing data indicates that inaccuracies in the air temperature data lead to similar sized errors in the predicted surface temperatures. Fluctuations in the forcing data that are not resolved by the model will affect a grass surface much more than a road surface, due to the relatively small thermal inertia of the grass. 相似文献
19.
强热带风暴碧利斯特大暴雨山洪成因分析 总被引：4，自引：3，他引：4
利用常规观测资料及候平均要素等资料,从前期天气背景、大气环流演变及产生强降水的动力、热力、水汽和不稳定条件,分析了0604号强热带风暴碧利斯登陆后在湘东南产生的特大暴雨过程。结果发现地面中尺度辐合线产生的上升运动与地形的动力抬升结合,加强了特大暴雨产生的动力作用,高温高湿有利于扰动形成和对流不稳定能量产生,为湘东南特大暴雨产生提供了极好的热力条件,南海季风爆发及西南季风槽的形成为湘东南暴雨上空提供了源源不断的水汽,大陆高压与副高对峙导致了"碧利斯"在西移过程中减缓。造成湘东南特大暴雨山洪除了气象成因外,薄弱的地质环境条件是"碧利斯"得以诱发地质灾害的内因。 相似文献
20.
对1989年7月20—21日内蒙古中西部的大暴雨,进行了诊断分析和数值试验。分析表明,南亚高压东北移在该地区对流层上部形成强辐散流场;西来短波槽诱发切变线北抬,使暖湿空气与干冷空气在该区上空交绥,扰动不稳定发展;暴雨落区与辐合线关系密切。数值试验表明,地形的动力作用和热力作用,是产生地面辐合的主要原因之一。 相似文献