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1.
Eichingeret al. (1993) discuss the use of a Raman lidar for measurements of water vapor fluxes and suggest that the method is superior to the use of standard micrometeorological, point sensor measurements. Although the lidar shows considerable promise for some purposes, we believe that their criticisms of point sensors are not warranted; that there are difficulties with their application of dissipation techniques to extract fluxes; and that they misinterpret the existence of plume structures as statistically significant spatial variations of turbulent fluxes. 相似文献
2.
Shiqi Yang Dejun Zhang Liang Sun Yongqian Wang Yanghua Gao 《Acta Meteorologica Sinica》2020,34(2):264-279
Temperature vegetation dryness index (TVDI) in a triangular or trapezoidal feature space can be calculated from the land surface temperature (LST) and normalized difference vegetation index (NDVI), and has been widely applied to regional drought monitoring. However, thermal infrared sensors cannot penetrate clouds to detect surface information of sub-cloud pixels. In cloudy areas, LST data include a large number of cloudy pixels, seriously degrading the spatial and temporal continuity of drought monitoring. In this paper, the Remotely Sensed Daily Land Surface Temperature Reconstruction model (RSDAST) is combined with the LST reconstructed (RLST) by the RSDAST and applied to drought monitoring in a cloudy area. The drought monitoring capability of the reconstructed temperature vegetation drought index (RTVDI) under cloudy conditions is evaluated by comparing the correlation between land surface observations for soil moisture and the TVDI before and after surface temperature reconstruction. Results show that the effective duration and area of the RTVDI in the study area were larger than those of the original TVDI (OTVDI) in 2011. In addition, RLST/NDVI scatter plots cover a wide range of values, with the fitted dry-wet boundaries more representative of real soil moisture conditions. Under continuously cloudy conditions, the OTVDI inverted from the original LST (OLST) loses its drought monitoring capability, whereas RTVDI can completely and accurately reconstruct surface moisture conditions across the entire study area. The correlation between TVDI and soil moisture is stronger for RTVDI (R = −0.45) than that for OTVDI (R = −0.33). In terms of the spatial and temporal distributions, the R value for correlation between RTVDI and soil moisture was higher than that for OTVDI. Hence, in continuously cloudy areas, RTVDI not only expands drought monitoring capability in time and space, but also improves the accuracy of surface soil moisture monitoring and enhances the applicability and reliability of thermal infrared data under extreme conditions. 相似文献
3.
The feasibility of combining two sensors for monitoring gas concentrations over a large area, is demonstrated via controlled simulation experiments. The network considered was a lidar combined with a point detector—the MIRAN spectrophotometer equipped with a flow-through gas cell. The first has a spatial scanning capacity and a very good time resolution, whereas the second has an inherent temporal memory effect. Algorithms for operating the two sensors coincidentally, taking their physical characteristics into account, were constructed. A good fit was found between measured concentrations in the MIRAN and reconstructed concentrations, using the lidar data for the same environment. Thus complementary operation can be achieved. The MIRAN temporal memory effect can be overcome by correlating the concentration calculated over different time intervals. 相似文献
4.
利用Nimbus-7行星反射率观测资料估算青藏高原地区的总辐射 总被引：10，自引：1，他引：10
本文利用1982年8月—1983年7月期间Nimbus-7行星反射率的月平均资料用“物理模式方法(Raschke and Preuss,1979)”估算了青藏高原及其邻近地区月平均地面总辐射的分布。得到的结果较好地反映了纬度、海拔与云量三个主要因子对总辐射分布的支配作用。根据高原及其邻近地区23个测站的资料,对总辐射的计算值与观测值进行了比较。统计分析表明,相关系数f=0.90,标准误差RMS=27w/m~2,平均绝对误差ABS=21w/m~2(相当于有效平均总辐射的11.7％)。文中还对误差来源和敏感性问题进行了讨论。 相似文献
5.
利用四川稻城地区2019年5~8月雨滴谱资料,研究不同雨强和不同降水的雨滴谱特征,并提出反射率因子Z、质量加权平均直径Dm粒、粒子总数浓度NT、含水量W与雨强R之间的关系,以及Gamma谱形状参数μ和斜率参数Λ之间的关系,并比较了该地区雨滴谱与我国其他地区的差异。结果表明:随着R增大,雨滴谱数浓度、粒径和谱宽也逐渐增大,雨滴谱逐渐变宽、变平坦;对流云雨滴谱明显比层状云宽、数浓度更高,谱型分别呈略微的上凸和下凹;W–R和Z–R幂函数关系最密切,其次为Dm–R和NT–R,μ–Λ很好符合二项式关系;稻城地区的Dm和截距参数Nw与其他区域不同,Dm仅大于亚洲季风区江淮流域,而Nw仅比华北地区大。 相似文献
6.
Michelle Simões Reboita Rosmeri Porfírio da Rocha Tércio Ambrizzi Ernesto Caetano 《Climate Dynamics》2010,34(6):873-889
A Regional Climate Model (RegCM3) 10-year (1990–1999) simulation over southwestern South Atlantic Ocean (SAO) is evaluated
to assess the mean climatology and the simulation errors of turbulent fluxes over the sea. Moreover, the relationship between
these fluxes and the rainfall over some cyclogenetic areas is also analyzed. The RegCM3 results are validated using some reanalyses
datasets (ERA40, R2, GPCP and WHOI). The summer and winter spatial patterns of latent and sensible heat fluxes simulated by
the RegCM3 are in agreement with the reanalyses (WHOI, R2 and ERA40). They show large latent heat fluxes exchange in the subtropical
SAO and at higher latitudes in the warm waters of Brazil Current. In particular, the magnitude of RegCM3 latent heat fluxes
is similar to the WHOI, which is probably related to two factors: (a) small specific humidity bias, and (b) the RegCM3 flux
algorithm. In contrast, the RegCM3 presents large overestimation of sensible heat flux, though it simulates well their spatial
pattern. This simulation error is associated with the RegCM3 underestimation of the 2-m air temperature. In southwestern SAO,
in three known cyclogenetic areas, the reanalyses and the RegCM3 show the existence of different physical mechanisms that
control the annual cycles of latent/sensible heating and rainfall. It is shown that over the eastern coast of Uruguay (35°–43°S)
and the southeastern coast of Argentina (44°–52°S) the sea-air moisture and heat exchange play an important role to control
the annual cycle of precipitation. This does not happen on the south/southeastern coast of Brazil. 相似文献
7.
L. R. Tsvang B. M. Koprov S. L. Zubkovskii A. J. Dyer B. Hicks M. Miyake R. W. Stewart J. W. McDonald 《Boundary-Layer Meteorology》1973,3(4):499-521
In the summer of 1970 an international intercomparison of turbulence measurement sensors was carried out at the Tsimlyansk field station of the Institute of Atmospheric Physics (IFA) Academy of Sciences of the U.S.S.R. Improved sonic anemometer sensors of the IFA were compared with the Kaijo sonic used by the Canadian group and with the fluxatron from CSIRO, Australia.Results from the experiment indicate that spectral and cospectral shapes are basically similar between the sonic anemometers. The spectra and cospectra of the fluxatron in the high-frequency region showed an attenuation which can be explained in terms of the response characteristics of the fluxatron. The maintenance of absolute calibration of the sensors in the field was found to be difficult, but when properly corrected for this variation, the measurements were found to agree within 13%, with a standard error of 0.2. A single point observation of turbulent fluxes at a few meters above the surface and averaged over a period of the order of one hour was shown to be representative of turbulent fluxes at the site. 相似文献
8.
Future climate in the Pacific Northwest 总被引：4，自引：2，他引：2
Climate models used in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) on the whole reproduce the observed seasonal cycle and twentieth century warming trend of 0.8°C (1.5°F) in the Pacific Northwest, and point to much greater warming for the next century. These models project increases in annual temperature of, on average, 1.1°C (2.0°F) by the 2020s, 1.8°C (3.2°F) by the 2040s, and 3.0°C (5.3°F) by the 2080s, compared with the average from 1970 to 1999, averaged across all climate models. Rates of warming range from 0.1°C to 0.6°C (0.2°F to 1.0°F) per decade. Projected changes in annual precipitation, averaged over all models, are small (+1% to +2%), but some models project an enhanced seasonal cycle with changes toward wetter autumns and winters and drier summers. Changes in nearshore sea surface temperatures, though smaller than on land, are likely to substantially exceed interannual variability, but coastal upwelling changes little. Rates of twenty-first century sea level rise will depend on poorly known factors like ice sheet instability in Greenland and Antarctica, and could be as low as twentieth century values (20 cm, 8″) or as large as 1.3 m (50″). 相似文献
9.
A. Tunick 《Meteorology and Atmospheric Physics》2005,90(3-4):159-164
Summary Due to the increased use of laser and ground-to-satellite communications the need for reliable optical turbulence information
is growing. Optical turbulence information is important because it describes an atmospheric effect that can degrade the performance
of electromagnetic systems and sensors, e.g., free-space optical communications and infrared imaging. However, analysis of
selected past research indicates that there are some areas (i.e., data and models) in which optical turbulence information
is lacking. For example, line-of-sight optical turbulence data coupled with atmospheric models in hilly terrain, coastal areas,
and within cities are few in number or non-existent. In addition, the bulk of existing atmospheric computer models being used
to provide estimates of optical turbulence are basically one-dimensional in nature and assume uniform turbulence conditions
over large areas. As a result, current optical turbulence theory and models may be deficient and in error for inhomogeneous
(nonuniform) turbulence conditions, such as those that occur in urban environments or environments with changing topography
and energy budgets. While it is anticipated that theoretical advances in environmental physics (and like disciplines) will
be a catalyst for much new work this area, in the interim, we suggest that some very practical computational research can
be performed to extend existing low-atmospheric turbulence and micrometeorological calculations beyond current limitations. 相似文献
10.
This paper investigates the optimal observational array for improving the initialization of El Niño-Southern Oscillation predictions by exploring the sensitive areas for target observations of two types of El Niño predictions. The sensitive areas are identified by calculating the optimally growing errors (OGEs) of the Zebiak–Cane model, as corrected by the optimal forcing vector that is determined by assimilating the observed sea surface temperature anomalies (SSTAs). It is found that although the OGEs have similar structures for different start months of predictions, the regions covered by much large errors for the SSTA component tend to locate at different zonal positions and depends on the start months. Furthermore, these regions are also in difference between two types of El Niño events. The regions covered by large errors of OGEs represent the sensitive areas for target observations. Considering the dependence of the sensitive areas on related El Niño types and the start months of predictions, the present study propose a quantitative frequency method to determine the sensitive areas for target observations associated with two types of El Niño predictions, which is expected to be applicable for both types of El Niño predictions with different start months. As a result, the sensitive areas that describe the array of target observations are presented with a reversal triangle-like shape locating in the eastern Pacific, specifically the area of 120°W–85°W, 0°S–11°S, and an extension to the west along the equator and then gathering at the 180° longitude and the western boundary. “Hindcast” experiments demonstrated that such observational array is very useful in distinguishing two types of El Niño and superior to the TAO/TRITON array. It is therefore suggested that the observational array provided in the present study is towards the optimal one and the original TAO/TRITON array should be further optimized when applied to predictions of the diversities of El Niño events.
相似文献11.
依据1990~2013年江苏省能源消费统计资料和1990、1995、2000、2005、2010年的人口空间分布数据,估计江苏省人为热排放量、探讨其时空分布特征并预测其未来变化趋势。研究结果表明,20多年来江苏省的人为热排放量持续增长,从1990年全省平均的0.59 W/m~2增加到2013年的2.85 W/m~2。排放的空间分布也不均匀,总体上江苏南部地区的排放通量高于江苏北部。近些年江苏省的人为热排放已成为区域问题,高值区已连接成片,2010年江苏省大部分地区的人为热排放高于2.5 W/m~2,南部主要城市排放通量大于10 W/m~2、北部城市也多大于5 W/m~2。江苏各城市的城区人为热排放通量稳步增长,2002年后增长加速、增量最高可达到2 W m~(-2) a~(-1)。在2030年和2050年江苏省的平均人为热排放通量将分别达到5.7 W/m~2和9.1 W/m~2,可能对中国东部的气候和大气环境产生重要影响。 相似文献
12.
城区与郊区不同地形地貌下云地闪分布规律初步研究 总被引：2，自引：0，他引：2
利用上海3台SAFIR3000闪电定位仪的测量数据、计算机软件技术和数据统计方法对上海地区云地闪的分布规律进行了研究,得出了以下结论：①受地形地貌及高大建筑的影响,上海地区的云地闪分布规律是南北多,东西少,城区多,郊区少;②在郊区发生的云地闪密度虽然低于城区,但是其雷电流的平均强度要高于城区;③上海地区14：00-21：00是云地闪发生最为频繁的时间段。雷暴日是用于表征某地雷电活动的频繁程度并据此进行风险评估及确定雷电防护等级的一个重要参数,但此参数在实际应用过程中存在着一些问题,文章提出了用＂闪电密度＂或者＂地闪密度＂代替雷暴日的设想。 相似文献
13.
The atmospheric heat sources of large plateaus strongly influence the general circulation particularly in the summer season. The Bolivian plateau and the adjacent areas affect the upper tropospheric flow in a typical summer month by developing an anticyclone and deflecting the prevailing westerlies. The plateau initially warms the atmosphere through sensible heating and then through latent heating as thunderstorms develop.The atmospheric heat source over the Bolivian and adjacent plateau was computed employing conventional surface and satellite radiation data for the mean January 1979. Because of a lack of direct ground temperature data, the surface radiation was estimated following an empirical formula devised for some earlier Tibetan studies.The results revealed that the latent heating developing in the eastern and northeastern part of the plateau is the biggest contributor to the atmospheric heat source (500 W m-2). A comparison of these results against similar recent results from Tibet showed that the atmospheric heat source in South America is stronger than that over Tibet, primarily because of increased rainfall over Bolivia. 相似文献
14.
The radiance lights data in 2006 from the National Oceanic and Atmospheric Administration Air Force Defense Meteorological Satellite Program/Operational Linescan System (DMSP/OLS) and authoritative energy data distributed by the United State Energy Information Administration were applied to estimate the global distribution of anthropogenic heat flux.A strong linear relationship was found to exist between the anthropogenic heat flux and the DMSP/OLS radiance data.On a global scale,the average value of anthropogenic heat flux is approximately 0.03 W m 2 and 0.10 W m 2 for global land area.The results indicate that global anthropogenic heat flux was geographically concentrated and distributed,fundamentally correlating to the economical activities.The anthropogenic heat flux concentrated in the economically developed areas including East Asia,Europe,and eastern North America.The anthropogenic heat flux in the concentrated regions,including the northeastern United States,Central Europe,United Kingdom,Japan,India,and East and South China is much larger than global average level,reaching a large enough value that could affect regional climate.In the center of the concentrated area,the anthropogenic heat flux density may exceed 100 W m 2,according to the results of the model.In developing areas,including South America,Central and North China,India,East Europe,and Middle East,the anthropogenic heat flux can reach a level of more than 10 W m 2 ;however,the anthropogenic heat flux in a vast area,including Africa,Central and North Asia,and South America,is low.With the development of global economy and urban agglomerations,the effect on climate of anthropogenic heat is essential for the research of climate change. 相似文献
15.
Indirect Radiative and Climatic Effects of Sulfate and Organic Carbon Aerosols over East Asia Investigated by RIEMS 
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下载免费PDF全文 The indirect radiative and climatic effects of sulfate and organic carbon aerosols over East Asia were investigated using a Regional Integrated Environment Model System (RIEMS) with an empirical aerosol-cloud parameterization.The first indirect radiative forcing was negative and ranged from-9-0 W m-2 in the domain.The maximum cooling,up to-9 W m-2,occurred in the Chongqing District in winter,whereas the cooling areas were larger during summer than in winter.Organic carbon (OC) aerosols were more abundant in winter than in summer,whereas the sulfate concentration during summer was much higher than during winter.The concentrations of sulfate and OC were comparable in winter,and sulfate played a dominant role in determining indirect radiative forcing in summer,whereas in winter,both sulfate and OC were important.The regional mean indirect radiative forcings were-0.73 W m-2 and-0.41 W m-2 in summer and winter,respectively.The surface cooling caused by indirect effects was more obvious in winter than that in summer.The ground temperature decreased by ～1.2 K in most areas of eastern China in winter,whereas in summer,the temperature decreased (～-1.5 K) in some regions,such as the Yangtze River region,but increased (～0.9 K) in the areas between the Yellow and Yangtze Rivers.In winter,the precipitation decreased by 0-6 mm in most areas of eastern China,but in summer,alternating bands of increasing (up to 80 mm) and decreasing (～-80 mm) precipitation appeared in eastern China. 相似文献
16.
Antonio Orsini Claudio Tomasi Francescopiero Calzolari Marianna Nardino Alessandra Cacciari Teodoro Georgiadis 《Atmospheric Research》2002,61(4)
Simultaneous measurements of downwelling short-wave solar irradiance and incoming total radiation flux were performed at the Reeves Nevè glacier station (1200 m MSL) in Antarctica on 41 days from late November 1994 to early January 1995, employing the upward sensors of an albedometer and a pyrradiometer. The downwelling short-wave radiation measurements were analysed following the Duchon and O'Malley [J. Appl. Meteorol. 38 (1999) 132] procedure for classifying clouds, using the 50-min running mean values of standard deviation and the ratio of scaled observed to scaled clear-sky irradiance. Comparing these measurements with the Duchon and O'Malley rectangular boundaries and the local human observations of clouds collected on 17 days of the campaign, we found that the Duchon and O'Malley classification method obtained a success rate of 93% for cirrus and only 25% for cumulus. New decision criteria were established for some polar cloud classes providing success rates of 94% for cirrus, 67% for cirrostratus and altostratus, and 33% for cumulus and altocumulus.The ratios of the downwelling short-wave irradiance measured for cloudy-sky conditions to that calculated for clear-sky conditions were analysed in terms of the Kasten and Czeplak [Sol. Energy 24 (1980) 177] formula together with simultaneous human observations of cloudiness, to determine the empirical relationship curves providing reliable estimates of cloudiness for each of the three above-mentioned cloud classes. Using these cloudiness estimates, the downwelling long-wave radiation measurements (obtained as differences between the downward fluxes of total and short-wave radiation) were examined to evaluate the downwelling long-wave radiation flux normalised to totally overcast sky conditions. Calculations of the long-wave radiation flux were performed with the MODTRAN 3.7 code [Kneizys, F.X., Abreu, L.W., Anderson, G.P., Chetwynd, J.H., Shettle, E.P., Berk, A., Bernstein, L.S., Robertson, D.C., Acharya, P., Rothman, L.S., Selby, J.E.A., Gallery, W.O., Clough, S.A., 1996. In: Abreu, L.W., Anderson, G.P. (Eds.), The MODTRAN 2/3 Report and LOWTRAN 7 MODEL. Contract F19628-91-C.0132, Phillips Laboratory, Geophysics Directorate, PL/GPOS, Hanscom AFB, MA, 261 pp.] for both clear-sky and cloudy-sky conditions, considering various cloud types characterised by different cloud base altitudes and vertical thicknesses. From these evaluations, best-fit curves of the downwelling long-wave radiation flux were defined as a function of the cloud base height for the three polar cloud classes. Using these relationship curves, average estimates of the cloud base height were obtained from the three corresponding sub-sets of long-wave radiation measurements. The relative frequency histograms of the cloud base height defined by examining these three sub-sets were found to present median values of 4.7, 1.7 and 3.6 km for cirrus, cirrostratus/altostratus and cumulus/altocumulus, respectively, while median values of 6.5, 1.8 and 2.9 km were correspondingly determined by analysing only the measurements taken together with simultaneous cloud observations. 相似文献
17.
超声测风仪因启动风速小、无转动部件、不破坏风场、测量精度高等特点,适用于多种行业的测风需求。超声波测风的相关检定规程当前在国内尚未正式制定。本文借鉴风杯检定规程所选择的风速测试点,在HDF-720低速回路风洞中,对超声测风仪在不同角度下进行了测试数据统计分析。结果表明:超声测风仪可以安装在工作段面较大的风洞中进行测试,由于超声探头存在阴影效应,对于同一风速,不同角度上的测量结果稍有差异,而且不同风速对应的差异也不同。利用超声测风仪进行风速实时测量时,必须结合上述测试分析,按照超声传感器的安装角度,对测量值进行相应修正。 相似文献
18.
本文介绍一种利用FY-4A成像仪遥感数据和全球预报系统(GFS)资料估算全天空地表长波辐射通量的反演方法。该方法通过辐射传输模拟和统计回归计算建立云天地表下行长波辐射通量的反演模式,并基于GFS资料处理云覆盖地区的地表上、下行长波辐射通量。这种全天空状况下两种通量的反演结合了FY-4A晴空地表长波辐射业务产品和本文反演模式处理的云天地表上、下行长波辐射通量。2018年9月1日的处理结果与Aqua/CERES同类产品相对比,精度为:RMSE=20.52 W·m^-2,R=0.9481,Bias=3.3 W·m^-2(夜间地表下行辐射通量对比);RMSE=25.58 W·m^-2,R=0.9096,Bias=5.4 W·m^-2(白天地表下行辐射通量对比);RMSE=10.97 W·m^-2,R=0.9762,Bias=-3.3 W·m^-2(夜间地表上行辐射通量对比);RMSE=19.97 W·m^-2,R=0.9283,Bias=5.0 W·m^-2(白天地表上行辐射通量对比)。这些结果表明本文发展的方法能够反演出精度较好的云天上下行长波辐射通量资料,为今后利用FY-4后续星处理生成全天空状况下的地表长波辐射通量产品奠定了理论基础。 相似文献
19.
利用1km和5km多源融合格点实况数据和四川地面观测站点资料,采用预报准确率、平均绝对误差、均方根误差和Alpha Index(AI)等统计量,选取2020年夏季四川2次高温天气过程对多源融合格点实况数据的质量进行了检验评估。研究结果表明:多源融合格点实况数据利用邻近插值方法插值到站点优于双线性插值;误差大值区主要位于高海拔地区,如川西高原、攀西地区及盆地山周;AI指数接近于0,多源融合格点实况数据没有随机误差,较为接近理想值;1km分辨率融合格点实况数据在四川的适用性优于5km,误差≤2℃的准确率可达98%,且均方根误差< 1。 相似文献
20.
应用欧洲中期预报中心的FGGEⅢ-b个客观分析资料计算了1979年7月热带大气的动能平衡。热带环流系统的动能主要集中在定常涡旋部分。对流层下层,105°E和150°E为两半球间瞬变涡旋的通道。对流层上层,瞬变涡旋的通道和洋中槽相联系,位于150°E和30°W附近。 索马里急流是对流层下层制造动能的主要环流系统。对流层上层,南亚东风急流入口区制造动能,出口区破坏动能,其动能收支与中纬度西风急流相似。 非洲-阿拉伯海季风区和孟加拉湾—南海季风区的动能平衡很不相同。动能的垂直输送可能在季风环流中很重要。 相似文献