共查询到20条相似文献，搜索用时 109 毫秒
1.
《武汉大学学报(信息科学版)》2010,(6)
以1a的探空资料为参照,对南半球4个不同季节COSMIC掩星观测的折射指数、温度及气压廓线在0～30km高度区间的精度进行了分析。结果表明,虽然就整个高度区间平均而言,春季掩星廓线的精度最差,但不同高度区间掩星廓线的精度差别较大。无论折射指数、气压还是温度,掩星廓线在5～25km区间的精度都优于0～5km与25～30km区间。在0～5km的低对流层,由于水汽的影响,夏季的折射指数廓线精度最低;冬季则最高。在5km以上,夏季气压廓线的精度比其他季节高。不同季节各高度层掩星温度廓线的精度则无显著差异。 相似文献
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利用折射率协方差变换法采用2007—2014年COSMIC(Constellation Observing System for Meteorology,Ionosphere and Climate)掩星观测数据研究了中国陆地区域对流层顶高度的时空变化特征。实验结果表明:中国陆地区域的对流层顶高度随纬度变化,呈现出"南高北低"的格局;而对流层顶处的温度和压强分布与高度分布相反。同时,中国陆地区域内对流层顶高度表现出较强的季节相关性,中国大部分陆地地区通常夏季对流层顶最高,冬季对流层顶最低;但在低纬地区(16°N～26°N)表现相反。在30°N～40°N之间的亚热带区域四季的变化较为显著,且存在明显的等值线。采用中位数斜率回归法分析了2007—2014年中国陆地区域对流层顶高度的年际变化,发现中国陆地区域对流层顶高度平均每年升高6.3 m,温度平均每年下降0.002 K,压强平均每年下降0.15 hPa。 相似文献
3.
《武汉大学学报(信息科学版)》2021,(4)
大气温度和湿度是描述大气动力和热力状态的重要参数。重点分析武汉地区由微波辐射计测量获得的温度和湿度廓线、大气边界层高度(atmospheric boundary layer height,ABLH)以及液态水路径(liquid water path,LWP)廓线的日变化及季节性变化。首先在有云和无云情况下,对RPG-HATPRO型微波辐射计和探空气球的探测结果进行比较。微波辐射计反演得到的温度、湿度在2 km以下相较于探空气球偏低,2 km以上则均表现为偏高;观测精度会因天气条件的不同而变化,使用微波辐射计产品时,应着重考虑云的影响。然后分析2011—2015年各气象要素的日变化和季节变化,实现武汉地区对流层大气的热力学表征。ABLH从上午8时开始增加,下午15时达到最高值,之后开始下降,在夜间整体保持稳定。LWP在夜间含量要高于白天,冬季高于夏季。结合高度信息,分析得出相对湿度(relative humidity,RH)在0～1 km随高度的增加而上升,随后下降。对武汉地区气象参数的日变化与季节性变化进行观测与分析,为气象探测、大气污染研究、空气质量监测、天气预报等提供了可靠信息。 相似文献
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2013年中国发射了首颗进行全球导航卫星系统(global navigation satellite system,GNSS)掩星观测的气象卫星风云3号C星(Fengyun-3C,FY-3C),且已发布自2014年6月以来的FY-3C掩星大气产品,但目前还未见将其应用于大气边界层的相关研究。首次尝试利用FY-3C折射率产品确定边界层高度并进一步进行空间分布分析。结果表明,在小波协方差变换法基础上,进行尖锐度约束,能够确定FY-3C掩星低层大气折射率廓线中可能存在的突变,反演边界层高度。所得到的2015―2018年各年边界层高度全球分布在不同纬度及海洋和陆地上的差异基本体现了边界层与地表气候及地形的关系,但FY-3C折射率产品在低层大气的精度和垂直分辨率相对较低。因此,反演成功率总体上较低,反演结果对边界层高度空间分布细节特征的呈现仍有待提升。 相似文献
6.
《遥感学报》2000,4(Z1):38-44
MODIS的设计目的是能够每隔1-2天测量一次全球范围生物的和物理的过程.我们可以从该仪器提供的数据中获得进一步的地球表面和低层大气的全球动力和过程信息.对MODIS数据,利用遗传算法,首先从大气温度探测波段中,反演得到大气温度廓线信息;然后从水汽波段中获得水汽廓线信息;最后在已有的温、湿廓线基础上,校正测量辐射亮度数据.校正了大气影响后,利用MODIS29、31、32大气窗口波段,采用比辐射率约束方法(Emissivityboundsmethod)缩小波段比辐射率取值范围,然后采用遗传算法实现陆面温度、波段比辐射率等地表参数的同时反演.模拟试验表明,利用遗传算法可以从MODIS数据中获得较为精确的大气廓线信息和地面参数信息,为全球温室效应和全球变化研究提供支持. 相似文献
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介绍了利用GPS掩星资料反演大气重力波势能的方法,给出了从COSMIC(constellation observing system for meteorology, ionosphere and climate)干温廓线出发,扰动温度廓线提取及势能廓线反演的具体流程,进而对2011年夏季和冬季20～30 km重力波势能的全球分布及季节变化特征进行了分析,结果与国内外已有文献基本一致。 相似文献
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大气水汽在遥感反演地表温度中起到关键作用,精确的大气水含量对于提升反演精度有着重要意义,而热红外方法是夜晚获得区域大气水汽含量的唯一方法。本研究采用热红外方法中的改良分裂窗算法,首先,使用TIGR大气廓线与MODIS波谱响应函数通过MODTRAN辐射传输模式进行模拟,将大气廓线的水汽含量与大气透过率进行回归;然后,根据MODIS数据产品特点,使用2015年夏季MODIS数据观测角小于20°的范围进行反演;最后,将白天反演水汽分别与全球GPS地基大气水汽观测网络和MODIS近红外水汽产品进行比较,均方根误差分别为5.5 g/cm2和6.4 g/cm2,显示了高度的区域一致性。由于MODIS观测角度较大,本研究未对其他角度进行反演,若对其余角度的MODIS数据进行反演,可根据余弦角度变化,针对不同角度范围进行模拟与回归。 相似文献
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为定量分析临近空间大气环境参数的准确性,利用10年以上的TIMED和ENVISAT卫星探测数据,以及根据理想气体状态方程和地转风公式计算出的密度和风场结果,统计得到大气温度、密度、纬向风、经向风和合成风的分布,并与中国参考大气开展对比验证,分析中国区域内临近空间大气参数误差随高度、纬度和经度的季节变化规律,对于临近空间卫星数据应用、环境特性分析和气象保障具有重要意义。研究表明:温度偏差在55 km高度以上的春季和秋季沿纬向逐渐减小,密度偏差随高度降低逐渐增大,沿经向在30 km高度以下存在偏差较大的经度带。纬向风偏差在夏季随高度的变化特征明显不同,沿纬向在40—70 km高度逐渐减小;经向风偏差在40 km高度以下沿纬向均匀分布,且季节性差异较小;合成风偏差随高度的震荡特征明显,沿纬向在秋季的40—60 km高度先减小后增大,沿经向在春季的30—45 km高度呈不断减小趋势。 相似文献
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利用中国第24次南极考察期间获取的南大洋上空走航式大气CO2数据和大气红外探测器(AIRS)探测的辐射率,进行基于纬度分类下的统计回归,其结果作为物理反演的初始猜测场。通过逐线积分辐射传输模式,利用AMSU大气温度廓线和AIRS中13个通道的辐射测值反演南大洋上空的大气CO2浓度廓线,与WDCGG提供的固定站点下的大气CO2浓度进行比较,反演精度随纬度的变化而变化,从低纬到高纬相对误差分别为0.31%、1.17%、2.63%。与同期国外卫星产品CO2/AIRS比较,相对误差为1.11%、1.07%。 相似文献
11.
水汽标高是一个反映水汽垂直分布特征的参数,也是全球导航卫星系统(global navigation satellite system,GNSS)对流层天顶湿延迟改正和GNSS水汽层析中的一个辅助参数。本文对2006—2012年水汽标高的时间序列进行频谱分析,发现水汽标高在时间上呈现出年周期和半年周期变化,因此利用包含年周期和半年周期的三角函数来表达水汽的时变规律,然后利用欧洲中尺度天气预报中心(European Centre for Medium-range Weather Forecasting,ECMWF)的数据在全球1°×1°的格网点上分别拟合了三角函数的系数。通过上述方法首次构建了一个全球适用的水汽标高模型GSH,该模型既体现了水汽标高的时变特性又考虑了其地理差异。以无线电探空数据为参考,GSH具有-0.19km的偏差(bias)和1.81km的均方根误差(root mean square error,RMSE);以ECMWF数据为参考,GSH具有0.04km的bias和1.52km的RMSE。GSH整体上表现出了比较稳定的精度,可服务于GNSS气象学研究,也可为其他相关气象研究提供水汽标高参考。 相似文献
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南极中山站重力潮汐观测的海潮负荷效应 总被引：1，自引：0，他引：1
综合分析了LaCoste-Romberg(LCR)ET21高精度弹簧重力仪1998年12月26日至2000年1月9日在南极中山站的重力潮汐观测资料，采用目前普遍使用的Schwiderski、Csr3.0和Fes96.2全球海潮模型研究中山站重力潮汐观测的海潮负荷改正问题。结果表明在南极地区，目前的海潮模型存在较大的不确定性，还不足以精密确定该区域的海潮负荷改正。经海潮改正后，重力潮汐观测结果与潮汐理论值之间还存在比较大的差异，观测的周日（01）和半日（M2）潮波重力振幅因子与相应的理论值之间的平均偏差分别为3．8％和7．8％。南极地区附近海域海水的变化半导致该地区海潮负荷响应非常明显的季节性系统变化。 相似文献
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Attenuation effect on seasonal basin-scale water storage changes from GRACE time-variable gravity 总被引：3，自引：0，他引：3
In order to effectively recover surface mass or geoid height changes from the gravity recovery and climate experiment (GRACE)
time-variable gravity models, spatial smoothing is required to minimize errors from noise. Spatial smoothing, such as Gaussian
smoothing, not only reduces the noise but also attenuates the real signals. Here we investigate possible amplitude attenuations
and phase changes of seasonal water storage variations in four drainage basins (Amazon, Mississippi, Ganges and Zambezi) using
an advanced global land data assimilation system. It appears that Gaussian smoothing significantly affects GRACE-estimated
basin-scale seasonal water storage changes, e.g., in the case of 800 km smoothing, annual amplitudes are reduced by about
25–40%, while annual phases are shifted by up to 10°. With these effects restored, GRACE-estimated water storage changes are
consistently larger than model estimates, indicating that the land surface model appears to underestimate terrestrial water
storage change. Our analysis based on simulation suggests that normalized attenuation effects (from Gaussian smoothing) on
seasonal water storage change are relatively insensitive to the magnitude of the true signal. This study provides a numerical
approach that can be used to restore seasonal water storage change in the basins from spatially smoothed GRACE data. 相似文献
14.
Seasonal global mean sea level change from satellite altimeter, GRACE, and geophysical models 总被引：2，自引：1，他引：2
J. L. Chen C. R. Wilson B. D. Tapley J. S. Famiglietti Matt Rodell 《Journal of Geodesy》2005,79(9):532-539
We estimate seasonal global mean sea level changes using different data resources, including sea level anomalies from satellite
radar altimetry, ocean temperature and salinity from the World Ocean Atlas 2001, time-variable gravity observations from the
Gravity Recovery and Climate Experiment (GRACE) mission, and terrestrial water storage and atmospheric water vapor changes
from the NASA global land data assimilation system and National Centers for Environmental Prediction reanalysis atmospheric
model. The results from all estimates are consistent in amplitude and phase at the annual period, in some cases with remarkably
good agreement. The results provide a good measure of average annual variation of water stored within atmospheric, land, and
ocean reservoirs. We examine how varied treatments of degree-2 and degree-1 spherical harmonics from GRACE, laser ranging,
and Earth rotation variations affect GRACE mean sea level change estimates. We also show that correcting the standard equilibrium
ocean pole tide correction for mass conservation is needed when using satellite altimeter data in global mean sea level studies.
These encouraging results indicate that is reasonable to consider estimating longer-term time series of water storage in these
reservoirs, as a way of tracking climate change. 相似文献
15.
《International Journal of Digital Earth》2013,6(5):439-455
Abstract The purpose of this paper is to develop Advanced Very High Resolution Radiometer (AVHRR) Global Inventory Modelling and Mapping Studies (GIMMS) Normalised Difference Vegetation Index (NDVI; AVHRR GIMMS NDVI for short) based fraction of absorbed photosynthetically active radiation (FPAR) from 1982 to 2006 and focus on their seasonal and spatial patterns analysis. The available relationship between FPAR and NDVI was used to calculate FPAR values from 1982 to 2006 and validated by Moderate-resolution Imaging Spectroradiometer (MODIS) FPAR product. Then, the seasonal dynamic patterns were analysed, as well as the driving force of climatic factors. Results showed that there was an agreement between FPAR values from this study and those of the MODIS product in seasonal dynamic, and the spatial patterns of FPAR vary with vegetation type distribution and seasonal cycles. The time series of average FPAR revealed a strong seasonal variation, regular periodic variations from January 1982 to December 2006, and opposite patterns between the Northern and Southern Hemispheres. Evergreen vegetation FPAR values were close to 0.7. A clear single-peak curve was observed between 30°N and 80°N – an area covered by deciduous vegetation. In the Southern Hemisphere, the time series fluctuations of FPAR averaged by 0.7° latitude zones were not clear compared to those in the Northern Hemisphere. A significant positive correlation (P<0.01) was observed between the seasonal variation of temperature and precipitation and FPAR over most other global meteorological sites. 相似文献
16.
Research on surface water temperature (SWT) variations in large lakes over the Qinghai–Tibet Plateau (QTP) has been limited by lack of in situ measurements. By taking advantage of the increased availability of remotely sensed observations, this study investigated SWT variation of Siling Co in central QTP by processing complete MODIS Land surface temperature (LST) images over the lake covering from 2001 to 2013. The temporal (diurnal, intra-annul and inter-annul) variations of Siling Co SWT as well as the spatial patterns were analyzed. The results show that on average from late December to mid-April the lake is in a mixing state of water and ice and drastic diurnal temperature differences occur, especially along the shallow shoreline areas. The extent of spatial variations in monthly SWT ranges from 1.25 °C to 3.5 °C, and particularly large at nighttime and in winter months. The spatial patterns of annual average SWT were likely impacted by the cooling effect of river inflow from the west and east side of the lake. The annual cycle of spatial pattern of SWT is characterized by seasonal reversions between the shallow littoral regions and deep parts due to different heat capacity. Compared to the deep regions, the littoral shallow shoreline areas warms up quickly in spring and summer, and cool down drastically in autumn and winter, showing large diurnal and seasonal variation amplitudes of SWT. Two cold belt zones in the western and eastern side of the lake and warm patches along the southwestern and northeastern shorelines are shaped by the combined effects of the lakebed topography and river runoff. Overall, the lake-averaged SWT increased at a rate of 0.26 °C/decade during 2001–2013. Faster increase of temperature was found at nighttime (0.34 °C/decade) and in winter and spring, consistent with the asymmetric warming pattern over land areas reported in prior studies. The rate of temperature increase over Siling Co is remarkably lower than that over Bangoin station, which is probably attributable to the large heat capacity of water and partly reflects the sensitive of alpine saltwater lake to climate change. 相似文献
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全球地幔密度异常及其构造意义 总被引：4，自引：0，他引：4
利用扣除地形、莫霍面和核幔边界起伏影响的中长波大地水准面异常和全球地震层析成像资料,采用阻尼最小二乘方法反演计算了全球地幔6个不同层面上的密度异常分布。分析了全球密度异常与板块构造的关系,探讨了全球密度异常分布对板块运动的作用。全球地幔密度异常结果表明存在两个主要的密度异常中心：一个位于东经80°,北纬0°;另一个位于东经240°,北纬10°附近。 相似文献