共查询到19条相似文献，搜索用时 171 毫秒
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遥感反演水汽总量和云不总量的研究 总被引：4，自引：1，他引：3
本文从地基微波遥感方程出发,建立了双频地基微波辐射计遥感反演水汽总量和云水总量的方程,并用探空资料对反演方程的精度进行了检验. 相似文献
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利用地基微波辐射计反演兰州地区液态云水路径和可降水量的初步研究 总被引：7，自引：1，他引：6
液态云水路径 (liquid water path, LWP) 和可降水量 (precipitable water vapor, PWV) 是描述天气和气候的两个重要物理量。目前, 针对液态云水路径和可降水量的直接观测较少, 特别是在我国干旱半干旱黄土高原地区, 至今没有获得系统的观测值。本文利用兰州大学半干旱气候与环境监测站 (SACOL) 近两年的微波辐射仪观测资料, 分析了黄土高原半干旱区液态云水路径和可降水量的变化特征。首先引入Liljegren et al.(2001) 的反演方法并加以改进, 计算得到适合黄土高原地区的反演参数, 利用改进后的反演方法计算近两年的液态云水路径和可降水量。分析结果显示, 与TP/WVP-3000型12通道微波辐射计的直接输出结果相比, 本文反演结果与实际情况更加吻合。在SACOL代表的黄土高原地区, 95%的云水路径值都在150 g/m2以下, 95%的可降水量值都在3 cm以下。由于SACOL的降水受亚洲季风的影响, 液态云水路径日均值冬季最小, 秋季最大, 其日变化规律显示半干旱区液态云水路径大体上呈双峰分布, 峰值主要出现在日出和日落时分。卫星反演资料的年变化趋势与地基反演结果比较吻合。因此, 运用卫星反演的液态云水路径来分析我国西北地区的空中云水资源是一种比较可信的手段。 相似文献
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本文介绍了在微波辐射计资料处理中探空资料的选取及处理方法,水汽和云水含量的计算,判云标准的建立和理论亮温的计算。交叉反演系数选择的反演方法大大提高了反演精度和资料处理的全天候能力。 相似文献
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地基遥感大气水汽总量和云液态水总量的研究 总被引：9，自引：1，他引：9
介绍了地基微波辐射计遥感反演大气柱中的水汽总量和云液态水总量的辐射传输原理和反演方法。给出了实用的有气候代表性的北京地区4个季节的反演公式，并对反演公式进行了数值检验，分析了反演精度：春、夏、秋、冬4季水汽总量反演的相对标准偏差分别为3．1％、1．6％、2．2％和2．4％。用反演公式反演在香河探测的NASA微波辐射计资料发现：微波辐射计反演的水汽总量平均比探空测量值偏大O．21cm，二者的线性相关系数为0．988．均方根误差为0．16cm：云液态水总量除降水云天外．值均在0．1mm以下。 相似文献
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基于极轨卫星NOAA-15上的微波温度计AMSU-A（Advanced Microwave Sounding Unit-A）多年亮温观测资料,建立了全球海洋上的云液态水路径反演产品,并通过对比ERA5和FNL/NCEP再分析资料的云水路径产品,分析了反演产品对云液态水路径气候变化特征的再现能力,进一步通过线性回归和EEMD（Ensemble Empirical Mode Decomposition）方法分别分析了太平洋地区大气云水路径的线性和非线性气候变化趋势特征。结果表明,云水路径反演资料可以很好的再现多年平均空间分布特征及相应的气候变化趋势,云水路径气候趋势表现出明显的纬度带特征,增多和减小趋势随纬度带间隔出现,而且在北半球东太平洋地区,云水路径气候趋势的纬度带特征有向北迁移的现象。相比而言,反演产品的气候趋势与ERA5再分析资料有更好的相似性,而FNL资料对趋势的纬度带特征,尤其是纬度带特征的北移现象未能很好的再现,只是表现为赤道地区水汽减少,而两侧云水路径显著增加的特征。 相似文献
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《气象与环境学报》2016,(2)
液态云水路径是气象学和云雾物理的一个重要参数,其定量测量对气候变化及灾害性天气的监测和预报均具有十分重要的作用.本文利用AUQA卫星携带的微波成像仪AMSR-E和中分辨率成像光谱仪MODIS确定微波极化通道亮温与大气含水量ω的关系,并改进双极化参数法.结果表明:利用AMSR-E的89.0 GHz和36.5 GHz微波极化通道亮温数据可直接反演液态云水路径,并可依据MODIS反演的大气含水量ω将反演分辨率估算至1 km.反演结果与MODIS云图路径吻合,与NCEP 1°×1°的6 h液态云水路径垂直积分总含量资料进行对比,表明反演结果误差小于0.04 kg·m~(-2). 相似文献
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云液态水路径是气候和天气系统分析的重要参数,可以从卫星观测资料反演获得.目前,基于卫星微波探测仪器观测资料的云水算法可由23.8和31.4 GHz两个通道产生.本研究使用先进技术微波探测仪(ATMS)观测数据,对物理和经验两种算法反演出的云液态水路径进行验证评估.结果表明,经验算法和物理算法都可以描述云液态水在全球洋面... 相似文献
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The ability of the Tropical Rainfall Measuring Mission Microwave Imager(TRMM/TMI)forcloud liquid water(CLW)retrieval has been demonstrated in this study.Due to the greatsensitivity of the TMI 85.5 GHz channels to CLW,the liquid water path(LWP)ofnonprecipitating clouds over land can be successfully estimated using the VDISORT model basedon the iteration steps.Both the vertical-polarized 85. 5 GHz single-channel method and thepolarization-difference of 85.5 GHz method were applied to the LWP estimates over land regionsduring the Huaihe River Basin Energy and Water Cycle Experiment(HUBEX)in China.Theretrieval results show reasonable agreement with the ground-based microwave radiometermeasurements.When the surface emissivity or skin temperature is difficult to be made sure,thepolarization-difference method shows advantages of providing estimates of LWP especially for lowclouds because of its extremely insensitiveness to the surface skin temperature. 相似文献
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用TRMM/TMI估算HUBEX试验区的云中液态水 总被引：4，自引：3，他引：4
文中应用热带降雨测量卫星微波成像仪的微波遥感资料反演云中液态水。由于微波成像仪85.5 GHz通道对云中液态水非常敏感,通过离散纵坐标矢量辐射传输模式,运用迭代的方法可以有效地反演出陆地上空非降水云中的液态水路径。在淮河流域能量与水分循环试验中,分别运用微波成像仪85.5 GHz垂直极化单通道和微波成像仪85.5 GHz极化亮温差两种方法来估算陆地上空的云中液态水路径,反演结果与地基微波辐射计的测量结果是较为一致的。当地表比辐射率或地表温度误差较大时,用极化亮温差法估算云中液态水路径相对较好,尤其是对于低云,因为该方法对地表温度不敏感。 相似文献
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该文利用地基双频（22.235GHz（1.35cm）和35.3GHz（8mm））微波辐射计和热带降雨测量卫星微波成像仪（TRMM/TMI）两种被动微波遥感资料分别反演安徽寿县地区云中液态水含量，运用统计回归方法得到该地区云水含量的反演公式，揭示了该地区云中液态水含量存在一个阈值0.4mm，当云中液态水含量超过这一阈值时，该地区一般就会出现降水。在降水发生之前，水汽和云中液态水含量均会出现一个显著增加的过程，而在降水结束之后则会出现一个显著减少的过程。 相似文献
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183.31 GHz微波辐射计在探测低含量水汽时具有优势,但也存在通道饱和问题,定量研究该问题对明确该类型仪器探测水汽能力和适用范围具有重要意义。基于天津市人工影响天气办公室增雨飞机运-12搭载的183.31 GHz微波辐射计GVR（G-band water Vapor Radiometer）,采用探空资料对该辐射计4个通道进行饱和问题研究,定量计算其饱和阈值及探测灵敏度,分析各通道水汽探测能力及适用范围。结果表明:机载微波辐射计4个通道水汽探测灵敏度及饱和阈值与观测高度有关,当水汽含量较低时,通道1（（183±1）GHz）观测高度越高灵敏度越高,通道3（（183±7）GHz）和通道4（（183±14）GHz）观测高度越高灵敏度越低,通道2（（183±3）GHz）灵敏度几乎不受观测高度影响,通道1和通道4观测高度越高积分水汽探测饱和阈值越小,观测高度越低饱和阈值越大,通道2和通道3饱和阈值几乎不受观测高度影响。晴空条件下选择水汽探测能力最强的单通道对积分水汽含量进行反演,当积分水汽含量处于0—1.3、1.3—4.0和4.0—9.8 mm时,分别选择通道1、通道2、通道3作为反演通道,不同观测高度的积分水汽含量反演均适用。云的发射作用使辐射计各通道亮温升高,亮温升高幅度与云液态水含量、云与观测高度的距离及云厚有关,云液态水含量越大,各通道水汽探测灵敏度及饱和阈值越小;云天条件下选择水汽探测能力最强的双通道对积分水汽含量进行反演,以液态水路径区间来选择合适的水汽探测通道,液态水含量越高,积分水汽可探测范围越小。要探测到0.1 mm的积分水汽含量变化,机载微波辐射计（GVR）在晴空条件下的水汽探测适用范围为0—9.8 mm,其探测能力在云天条件下减弱,水汽探测适用范围因云液态水含量不同而不同。 相似文献
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Analysis of ice water path retrieval errors over tropical ocean 总被引：1，自引：0，他引：1
Retrieval of multi-layered cloud properties, especially ice water path (IWP), is one of the most perplexing problems in satellite cloud remote sensing. This paper develops a method for improving the IWP retrievals for ice-over-water overlapped cloud systems using Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and Visible and Infrared Scanner (VIRS) data. A combined microwave, visible and infrared algorithm is used to identify overlapped clouds and estimate IWP separately from liquid water path. The retrieval error of IWP is then evaluated by comparing the IWP to that retrieved from single-layer ice clouds surrounding the observed overlapping systems. The major IWP retrieval errors of overlapped clouds are primarily controlled by the errors in estimating the visible optical depth. Optical depths are overestimated by about 10–40% due to the influence of the underlying cloud. For the ice-over-warm-water cloud systems (cloud water temperature Tw > 273 K), the globally averaged IWP retrieval error is about 10%. This cloud type accounts for about 15% of all high-cloud overlapping cases. Ice-over-super-cooled water clouds are the predominant overlapped cloud system, accounting for 55% of the cases. Their global averaged error is 17.2%. The largest IWP retrieval error results when ice clouds occur over extremely super-cooled water clouds (Tw 6 255 K). Overall, roughly 33% of the VIRS IWP retrievals are overestimated due to the effects of the liquid water clouds beneath the cirrus clouds. To improve the accuracy of the IWP retrievals, correction models are developed and applied to all three types of overlapped clouds. The preliminary results indicate that the correction models reduce part of the retrieval error. 相似文献
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NUMERICAL STUDY OF REMOTE SENSING OF CLOUD LIQUID WATER CONTENT BY SPACE-BORNE COMBINED RADAR-RADIOMETER 总被引：1，自引：0，他引：1
A retrieval method of microwave(MW)space-borne remote sensing of cloud liquid watercontent by the combined radar-radiometer is suggested.A three-layer cloud model is chosen torepresent the typical stratified precipitating cloud.The retrieval method mainly follows ourpreviously suggested scheme with some modifications.Numerical comparative study shows that inspace-borne remote sensing of cloud liquid water content by the combined method is much betterthan by radar only;Also the retrieval accuracy of cloud liquid water content may be improvedwhen using the three-layer cloud model in the combined method. 相似文献
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NUMERICAL STUDY OF REMOTE SENSING OF CLOUD LIQUID WATER CONTENT BY SPACE-BORNE COMBINED RADAR-RADIOMETER* 
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下载免费PDF全文 A retrieval method of microwave(MW) space-borne remote sensing of cloud liquid water content by the combined radar-radiometer is suggested.A three-layer cloud model is chosen to represent the typical stratified precipitating cloud.The retrieval method mainly follows our previously suggested scheme with some modifications.Numerical comparative study shows that in space-borne remote sensing of cloud liquid water content by the combined method is much better than by radar only;Also the retrieval accuracy of cloud liquid water content may be improved when using the three-layer cloud model in the combined method. 相似文献
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The Microwave Radiation Imager(MWRI) on board Chinese Fengyun-3(FY-3) satellites provides measurements at 10.65, 18.7, 23.8, 36.5, and 89.0 GHz with both horizontal and vertical polarization channels. Brightness temperature measurements of those channels with their central frequencies higher than 19 GHz from satellite-based microwave imager radiometers had traditionally been used to retrieve cloud liquid water path(LWP) over ocean. The results show that the lowest frequency channels are the most appropriate for retrieving LWP when its values are large. Therefore, a modified LWP retrieval algorithm is developed for retrieving LWP of different magnitudes involving not only the high frequency channels but also the lowest frequency channels of FY-3 MWRI. The theoretical estimates of the LWP retrieval errors are between 0.11 and 0.06 mm for 10.65-and 18.7-GHz channels and between0.02 and 0.04 mm for 36.5-and 89.0-GHz channels. It is also shown that the brightness temperature observations at10.65 GHz can be utilized to better retrieve the LWP greater than 3 mm in the eyewall region of Super Typhoon Neoguri(2014). The spiral structure of clouds within and around Typhoon Neoguri can be well captured by combining the LWP retrievals from different frequency channels. 相似文献
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The Microwave Radiation Imager (MWRI) on board Chinese Fengyun-3 (FY-3) satellites provides measurements at 10.65, 18.7, 23.8, 36.5, and 89.0 GHz with both horizontal and vertical polarization channels. Brightness temperature measurements of those channels with their central frequencies higher than 19 GHz from satellite-based microwave imager radiometers had traditionally been used to retrieve cloud liquid water path (LWP) over ocean. The results show that the lowest frequency channels are the most appropriate for retrieving LWP when its values are large. Therefore, a modified LWP retrieval algorithm is developed for retrieving LWP of different magnitudes involving not only the high frequency channels but also the lowest frequency channels of FY-3 MWRI. The theoretical estimates of the LWP retrieval errors are between 0.11 and 0.06 mm for 10.65- and 18.7-GHz channels and between 0.02 and 0.04 mm for 36.5- and 89.0-GHz channels. It is also shown that the brightness temperature observations at 10.65 GHz can be utilized to better retrieve the LWP greater than 3 mm in the eyewall region of Super Typhoon Neoguri (2014). The spiral structure of clouds within and around Typhoon Neoguri can be well captured by combining the LWP retrievals from different frequency channels. 相似文献