青藏高原晴空行星反照率与地面反照率关系的研究

本文利用了大气-地球系统的物理模型推导了晴空行星反照率与地面反照率之间的相互关系,指出当仅考虑一次地面反射时,行星反照率是地面反照率的一次线性函数,当考虑到大气与地面的多次反射时,两者的关系设为二次抛物线函数,并利用1986年中美青藏高原联合考察期间的地面辐射资料以及同期NOAA-9的GAC资料对上述关系进行了试验,结果表明,两种关系都能较好地反映出青藏高原行星反照率与地面反照率之间的关系,但二次函数表现的物理意义更为明确。 青藏高原作为一个特殊的地理类型,其行星反照率与地面反照率的相互关系与全球纬向平均相比较也有明显的差异,本文讨论了这些差异的物理意义,同时分别讨论了该地区可见光和近红外这二个通道的滤过反照率与地面分光谱反照率之间的关系。 青藏高原晴空反照率与地面反照率关系的研究为利用AVHRR资料反演青藏高原地面反照率的数值分布图提供了理论依据和具体方法。     

从NOAA卫星AVHRR资料反演中国区域地表反照率

由NOAA卫星AVHRR短波通道1、2反射率反演地表反照率需要3个反演模式,分别是窄-宽波段反射率转换模式、大气顶双向反射模式、大气订正模式.基于模式和国家卫星气象中心接收处理的NOAA-18 AVHRR1B数据,处理了2006年1月至2010年12月的中国区域地表反照率,由于云的影响,15天合成技术用来形成周期为15天的地表反照率数据文件.2006年、2010年2年的处理结果与MODIS同类产品对比,RMS为0.028～0.074、相关系数为0.76～0.93,误差较大出现在冬季,原因是两者15天合成方法不同;5年的日平均地表反照率与21个中国地面气象一级辐射站的观测测值作对比,结果是：RMS为0.053、相关系数为0.88.反演模式系统误差以及云和气溶胶影响是卫星反演地表反照率的主要误差来源.     

冬季青藏高原地面辐射平衡

本文根据实测资料建立了冬季青藏高原上地面辐射平衡与日照百分率、地面反射率之间的经验公式,并用此公式试验了纬度、时间、地面反射率和日照百分率对地面辐射平衡的影响。试验结果表明:冬季高原地面辐射能收支的盈亏状况是由地理纬度和地面反射率决定的。天空遮蔽状况(本文用日照百分率表示)仅影响其盈亏值的大小。亦即地面辐射平衡的地理分布形式由地理纬度和地面反射率所决定,但正、负中心的数值还受天空遮蔽状况的影响。冬季青藏高原地面辐射平衡场是一个由地理因子(地理纬度和自然地理带)作用下形成的基本场叠加上一个地面积雪区形成的扰动场。长江和黄河源区的巴颜喀拉山和藏北草原是冬季高原地面加热场最可能出现异常的关键区。     

青藏高原GLASS地表反照率产品精度分析

应用2003年青藏高原3个站点的地表反照率观测结果,对比分析了GLASS(Global LAnd Surface Satellites)地表反照率1 km×1 km分辨率产品的精度,结果表明,GLASS黑空反照率、白空反照率与地表反照率地面观测结果的总体变化趋势基本一致,能够有效地反映实际地表状态的变化;局地积雪和云覆盖对GLASS地表反照率产品的精度影响较大,云覆盖导致GLASS地表反照率可能比实际地表反照率高;消除云覆盖和局地积雪的影响后,GLASS黑空反照率、白空反照率与地表反照率地面观测结果的均方根误差显著降低,分别为0.0155和0.0190。     

中国大陆地区行星反射率的基本特征

本文应用1982年8月－1983年7月逐日的NOAA辐射收支资料（分辨率为2．5°×2．5°），分析了中国大陆地区各种代表性地理区域（塔克拉玛干沙漠、青藏高原、华北平原和长江中下游）的行星反射率的基本特征、云天行星反射率的空间分布图。并利用1982年8月－1983年7月青藏高原的地面观测资料对那曲等4个站的地表反射率与睛天行星反射率进行了比较。     

青藏高原地区地气系统太阳辐射能收支的研究

本文利用1982年8月—1983年7月Nimbus-7的月平均行星反射率资料和根据卫星资料得到的地面总辐射、地表反射率的估算结果,分析了青藏高原地区地气系统(大气顶)的太阳辐射能收支和地表、大气对太阳辐射吸收的时空变化特征,给出了表征太阳辐射能收支的一些基本参数,讨论了以行星反射率为基本参数表征大气、地表对太阳辐射吸收的参数化方法。分析表明:过渡季节5月份的行星反射率极小值的出现对青藏高原地区太阳辐射能收支有重要调节作用;全年平均而言,青藏高原地区被地气系统反射和被大气、地表吸收的太阳辐射的比例为37:18:45。     

利用NOAA-AVHRR遥感资料反演长江三角洲地表反照率的试验

利用NOAA－AVHRR的CH1和CH2资料，反演了长江三角洲地区地表反照率瞬时值，与前人给出的不同地面覆盖物反照率进行对比，表明对该地区的反演是可行的。还提出一种由单一时刻反照率推算一天中其他任意时刻反照率的方法，发现方法可靠。最后比较了太阳天顶角和地表状况对地表反照率的影响大小，发现二者量级相当，说明在短时、超短时数值模式中，必须同时考虑二者的作用。     

CHARACTERISTICS OF VARIATION IN SURFACE ALBEDO AND SNOW FORCING OVER THE TIBETAN PLATEAU*

The combination of field experiments and satellite observations is the fundamental way to understand the characteristics of spatial-temporal variation in surface albedo over the Tibetan(Qinghai-Xizang) Plateau. Under the condition without snow cover, the relatively regular annual variation cycle of the surface albedo can be expressed by an empirical formula. The effect of snow cover on the surface albedo in winter can be expressed by introducing two variables of snow forcing and sensitivity parameter. The existing satellite retrieved results of surface albedo may provide the digital grid data for describing the geographical distribution. However, some satellite retrieved surface albedos available over the Tibetan Plateau are obviously too low in winter. Taking the satellite derived results in summer as the background field representative of geographical distribution and combining the empirical formula of annual cycle based on the surface observations,a dynamic model of surface albedo is developed for the need of modeling the climatic influence of the underlying surface forcing of the Tibetan Plateau.     

青藏高原地区OLR与地面有效辐射关系的分析

青藏高原;;OLR;;地面有效辐射     

CHARACTERISTICS OF VARIATION IN SURFACE ALBEDO AND SNOW FORCING OVER THE TIBETAN PLATEAU

The combination of field experiments and satellite observations is the fundamental way tounderstand the characteristics of spatial-temporal variation in surface albedo over the Tibetan(Qinghai-Xizang) Plateau. Under the condition without snow cover, the relatively regular annualvariation cycle of the surface albedo can be expressed by an empirical formula. The effect of snowcover on the surface albedo in winter can be expressed by introducing two variables of snow forcingand sensitivity parameter. The existing satellite retrieved results of surface albedo may provide thedigital grid data for describing the geographical distribution. However, some satellite retrievedsurface albedos available over the Tibetan Plateau are obviously too low in winter. Taking thesatellite derived results in summer as the background field representative of geographicaldistribution and combining the empirical formula of annual cycle based on the surface observations,a dynamic model of surface albedo is developed for the need of modeling the climatic influence ofthe underlying surface forcing of the Tibetan Plateau.     

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

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。     

几种下垫面对紫外辐射的反射率

利用ＥＰＰＬＥＹ紫外辐射仪测量了６种下垫面对紫外辐射的反射率。初步结果是：（１）裸地、水泥地、草地、砂子和黑土的紫外反射率分别为２．４％，６．７％，２．１％，４．２％和６．６％，而新雪的紫外反射率为８３．５％。（２）紫外反射率均小于太阳总辐射的反射率，尤其是前５种下垫面。（３）紫外反射率的日变化与太阳总辐射反率的日变化相似。     

晴天地表太阳辐射的参数化

讨论了晴天地表太阳总辐射和地表太阳净辐射瞬时值的参数化方法。首先利用辐射传输模式和中纬度夏季标准大气廓线,分谱带计算晴天各种大气条件下地表反射率取定值时的地表太阳总辐射,并把所得的结果作为标准资料,提出参数化方案。然后将地表反射率的影响作为误差项进行订正,从而得到各种地表反射率条件下的晴天地表太阳净辐射的计算方法。该方法的拟合精度较高,拟合值与辐射模式标准值的平均相对误差在0.3%以下。该参数化公式可以用于大尺度数值模式中地表辐射平衡的计算,以期达到地表辐射平衡计算与模式积分同步进行的目的。     

青藏高原地表反照率计算研究

根据改进的甚高分辨率扫描辐射仪（ＡＶＨＲＲ）５个观测波段的光谱特征，经多次试验，设计了一组从卫星观测的地－气系统的辐射测值中提取晴空资料的多通道门槛值判识法和提取月平均反照率的合成法；并对１９９２年ＮＯＡＡ－１２卫星获取的ＡＶＨＲＲ资料进行计算处理，分析提取晴空数据，在此基础上按卫星轨道覆盖周期合成计算得到的晴空行星反照率和地表反照率，并且计算了逐月的地表反照率。对计算结果做了初步分析和认真比较。     

青藏高原地表反射率卫星反演资料的评估

该文重点介绍了ＩＳＣＣＰ资料中的地表可见光反射率资料及ＬｉＺｈａｎｑｉｎｇ等用参数化反演模式从ＥＲＢＥ宽带行星反射率得到的地表反射率资料。我们选择青藏高原及其邻近地区为目标区，结合高原野外地面观测资料对它们进行了比较和评估，分析了误差的可能原因，并提出了反演青藏高原地表反射率时注意的问题。     

Impact of soil moisture and winter wheat height from the Loess Plateau in Northwest China on surface spectral albedo

The understanding of surface spectral radiation and reflected radiation characteristics of different surfaces in different climate zones aids in the interpretation of regional surface energy transfers and the development of land surface models. This study analysed surface spectral radiation variations and corresponding surface albedo characteristics at different wavelengths as well as the relationship between 5-cm soil moisture and surface albedo on typical sunny days during the winter wheat growth period. The analysis was conducted using observational Loess Plateau winter wheat data from 2015. The results show that the ratio of atmospheric downward radiation to global radiation on typical sunny days is highest for near-infrared wavelengths, followed by visible wavelengths and ultraviolet wavelengths, with values of 57.3, 38.7 and 4.0%, respectively. The ratio of reflected spectral radiation to global radiation varies based on land surface type. The visible radiation reflected by vegetated surfaces is far less than that reflected by bare ground, with surface albedos of 0.045 and 0.27, respectively. Thus, vegetated surfaces absorb more visible radiation than bare ground. The atmospheric downward spectral radiation to global radiation diurnal variation ratios vary for near-infrared wavelengths versus visible and ultraviolet wavelengths on typical sunny days. The near-infrared wavelengths ratio is higher in the morning and evening and lower at noon. The visible and ultraviolet wavelengths ratios are lower in the morning and evening and higher at noon. Visible and ultraviolet wavelength surface albedo is affected by 5-cm soil moisture, demonstrating a significant negative correlation. Excluding near-infrared wavelengths, correlations between surface albedo and 5-cm soil moisture pass the 99% confidence test at each wavelength. The correlation with 5-cm soil moisture is more significant at shorter wavelengths. However, this study obtained surface spectral radiation characteristics that were affected by land surface vegetation coverage as well as by soil physical properties.     

Calculation of solar albedo and radiation equilibrium over the Qinghai-Xizang Plateau and analysis of their climatic features

1.IntroductionTopreciselyestimatethevaluesofalbedosatsurfaceandatmospherictop.surfacetotalradiationandearth--atmosphereoutgoinglongwaveradiationiscrucialtocalculatingradiationbalanceatsurfaceandatmospherictopandexploringoftheeffectoftheQXPatmosphericheatsourcesonatmosphericcirculations.Using1958--1960observationsofsurfacetotalradiation,albedoandsurfacemeteorologicalobservationsoverChina.ChenandGongetal.(1964.1965)investigated,throughanatmosphericradiationcalculationscheme.thedistributionchar…     

藏北地区冬季降雪对地面反射率的影响

藏北地区是冬季青藏高原上降雪次数较多、降雪量较大、可能出现较长时间地面积雪的地区之一。每次较强的隆雪均可造成该地区地面反射率一次较长时间异常，从而改变地面热源的强度和符号。     

青藏高原积雪的分布特征及其对地面反照率的影响

通过对１９８３年７月至１９９０年６月青藏高原主体５８个格点积雪资料进行ＥＯＦ分析发现，青藏高原主体积雪分布以西部兴都库什山脉。天山山脉以及南部喜马拉雅山脉为主；高原中部唐古拉山脉、北部昆仑山脉和东部巴颜喀拉山脉的积雪相对较少，青藏高原西部、南部的积雪变化与中部、北部和东部的积雪变化趋势存在反位相关系。另外，本文还对积雪对高原地面反照率的影响作了简单分析。     

On the angular correction of satellite radiation measurements: The performance of ERBE angular dependence model in the Arctic

Summary An angular dependence model (ADM) is needed to convert radiance measurements into fluxes. This paper provides an overview on the progress and issues related to the angular correction of radiation data at the top-of-the-atmosphere (TOA), followed by an investigation on the performance of the Earth Radiation Budget Experiment (ERBE) ADMs in the Arctic during summer. The variation of inferred albedo with viewing geometry indicates the merit of an ADM. The ERBE ADM for land does well as it leads to near constant albedos for given solar zenith angles. The ADM for snow/ice is least satisfactory when applied to the Arctic in summer. The performance of the ocean ADM is acceptable except at large solar zenith angles for which albedo increases with viewing zenith angle. Significant and systematic variation of albedo with viewing angle and relative azimuth angle are manifest when the overcast ERBE ADM is applied to over-cast-over-snow/ice scenes. A methodology for correcting ERBE ADMs was proposed by normalizing the anisotropic factor over bins containing sufficient measurements.With 6 Figures