FY-3A微波湿度计资料的扫描偏差特征分析

卫星辐射资料在数值天气预报系统中的直接同化中会受到系统偏差的影响。文章使用2010年1月20日06:00UTC FY-3A搭载的微波辐射计(MWHS)探测资料L1C格式产品,分析了亮度温度观测增量O-B随扫描角的分布特征,为FY-3A MWHS资料的偏差订正及直接同化提供参考。文章分析MWHS的5个通道观测亮度温度、模拟亮度温度、观测增量O-B亮度温度的全球分布图发现:所有通道中误差高值区都集中在中高纬地区,低纬地区偏差较小;窗区通道1、2的误差分布随空间变化增大,误差较大,不适合进行偏差订正,通道3、4、5的误差相对较小,适合进行偏差订正;通道3、4、5观测增量O-B与星下点偏差随扫描角的分布沿着星下点两端均不对称,其中,通道3和通道4的偏差较小,主要集中在±0.5 K范围内,分布在0轴附近;通道5的偏差较大,并扫描角分布变化较大,出现了双峰不对称的形状。

三轴稳定卫星扫描镜运动的偏差与补偿

根据带扫描镜运动的三轴稳定卫星姿态动力学方程 ,进行扫描镜扫描过程仿真 ,绘制扫描轨迹 ,计算由于卫星姿态引起的扫描镜扫描偏差。结果表明 ,扫描偏差有积累现象 ,且最大偏差值超过 GOES I- M卫星的许用扫描偏差值 ( 2 .8μrad)。提出了修正扫描镜运动控制方程的扫描镜运动补偿方法。仿真结果表明 ,用这种方法消除了扫描偏差的积累 ,使扫描镜光轴角度偏差值远小于2 .8μrad。修正方程简单 ,计算量很小 ,是一种补偿扫描偏差的有效方法。

风云三号卫星微波湿度计的扫描角偏差订正

首先统计分析了FY-3A卫星MWHS(Micro Wave Humidity Sounder,微波湿度计)2010年1月整月和8月28日—9月6日Level-1b全球观测亮度温度T_O和背景场(NCEP GFS 6 h预报场)用辐射传输模式(美国通用辐射传输模式CRTM 2.0版本)模拟的亮度温度T_B随扫描角的分布特征,发现通道3和4的观测随仪器扫描角有抖动、不连续现象。同时沿着仪器扫描线在星下点两测存在观测不对称现象,而且权重函数峰值越接近地面的通道该不对称现象越明显。在统计观测增量T_O-T_B随扫描角和纬度变化的基础上,定量给出了不同纬度带内(每隔5个纬度)MWHS通道3、4和5的扫描角偏差订正系数,该系数可直接提供给各种资料同化系统同化FY-3A MWHS资料时使用。

区域极轨卫星ATOVS辐射偏差订正方法研究

近年来,卫星辐射资料在数值天气预报(NWP)系统中的直接同化研究取得了长足进展。为了利用TIROS业务垂直探测器(ATOVS)的辐射资料,必须对卫星观测辐射值的系统性偏差进行订正。在ECMWF原全球TOVS辐射偏差订正方案基础上,结合ATOVS资料特征和中国的实际情况,建立了适用于区域NOAA-15/16/17极轨气象卫星ATOVS辐射资料的偏差订正方案。该方案偏差订正分两步进行:首先进行扫描偏差订正,然后进行气团偏差订正。扫描偏差是临边测量相对于星下点测量的系统偏差,统计显示该种偏差具有一定的纬度依赖性,所以订正时按每10度的纬度带分别进行订正。气团偏差订正主要就是根据当时的天气条件进行订正,而天气条件一般用预报因子来定量表示。文中从中国国家气象中心T213背景场导出预报因子:(1)1000—300 hPa的厚度,(2)200—50 hPa的厚度,(3)模式地表温度,(4)总可降水量。模式预报因子的使用从观念上将对观测值的订正变为对计算前向辐射值的订正问题。试验结果表明,订正结果显著。

偏差订正方法在IASI辐射率资料同化中的应用研究

根据IASI（Infrared Atmospheric Sounding Interferometer）的资料特征和GRAPES（Global/Regional Assimilation and Prediction System）同化系统的具体情况,建立了适用于业务使用的关于IASI辐射率资料的偏差订正方案,该方案包括扫描偏差订正和气团偏差订正。统计表明,IASI资料的扫描偏差不像微波资料一样具有明显的纬度依赖性,但在2x2的像元内存在某种特殊的扫描偏差,临边测量相对于星下点的扫描偏差可以用＂扫描角＂作为自变量而消除,而2x2的像元内的偏差只能通过稀疏化来规避;气团偏差主要根据当时的天气条件进行订正,利用模式背景场作为预报因子定量给出天气条件,采用1 000~300 h Pa的厚度、200~50 h Pa的厚度、50~20 h Pa的厚度以及模式地表温度作为预报因子。订正方案的试验结果显示,偏差能够长时间维持在比较低的稳定水平,订正结果显著。

Preparation of Composite Phase Change Material Based on Sol-Gel Method and Its Temperature-Adjustable Textile

In this study,the sol-gel method was introduced to prepare the composite phase change material (CPCM). The CPCM was added to fabric with coating techniques and the thermal activity of modified fabric was studied. In addition,the thermal property and the microstructure of CPCM were also discussed in detail by means of polarization microscope and differential scanning calorimeter,respectively. According to the analysis of main influencial factors of the property of CPCM,the optimal preparing technique was determined. It was proved that CPCM could exhibit a good thermal property while phase transformation process took place,and a better appearance of the fabric modified with CPCM could be obtained due to the fact that in a warm circumstance,the liquid-state phase change material could be firmly enwrapped and embedded in the three-dimensional network all the time during the phase transformation. Besides,the fabric treated with CPCM had a high phase-transition enthalpy and an appropriate phase-transition temperature. As a result,a desirable temperature-adjustable function appeared.

Adsorption mechanism of expanded graphite for oil and dyes

Expanded graphite （r-;G） shows higher adsorption capacity for oils than for dyes. To illustrate the different adsorption mechanism of EG for these pollutants, adsorption capacities of dyes and oil on EG were firstly studied. And then stepwise adsorption for oils was carried out with EG which has been saturated firstly by dyes, the difference between adsorbance of oil on EG was checked with deviation analysis. Scanning electronic microscopy （SEM） analysis was used to show structure difference of EG adsorbed different adsorbates. These used adsorbates were SD300 oil, basic fuchsine, Auramine lake yellow O and acid brilliant red 3B. The adsorption isotherm of dyes on EG is type 11 or type 1, and their equilibrium adsorbances are less than 1.0 g/g. While, adsorbance for SD300 oil can reach 104.5 g/g. Deviation analysis for stepwise adsorbances of oil shows no statistical significance. EG saturated firstly by dyes, still has an average adsorption capacity of 35 g/g for SD300 oil, and it does not change with the initial dyes concentration. SEM photos illustrate the adsorption of oil on EG is mainly filling, In the adsorption of dyes, there is severe breakage of the V-type pore and shrinkage of the particle. Kinetic difference is analyzed also.

Synthesis of functionalized triphenylene discotic liquid crystals and the influence of unsaturated periphery on mesomorphism

Twelve triphenylene discogens with unsaturated periphery (abbreviated as C18H6(OC5H11)6-x(OR)x(x=1,2,3), R=-C3H6CH==CH2(a),-C3H6C≡CH(b),-C2H4OCH==CH2(c)) were synthesized and characterized. The thermotropic liquid crystal prop-erties were studied by using polarized optical microscopy, differential scanning calorimetry and X-ray diffractometry. The results showed that all triphenylenes exhibited hexagonal columnar mesophase. The thermotropic studies showed that series a (alkene periphery) exhibited higher clearing points than the corresponding series b (alkyne periphery), while series c (vinyloxy periphery) exhibited highest clearing points and widest mesophase temperature ranges. We also found that the symmetric discogens sym-C18H6(OC5H11)3(OR)3 displayed higher melting points and clearing points than the asymmetric ones asym-C18H6(OC5H11)3(OR)3.