为了实现西太平洋及东亚区域FY-2F可见红外自旋扫描辐射计(VISSR)资料的直接同化,本文利用飓风天气预报模式(WRF For Hurricane,HWRF)和快速辐射传输模式(Community Radiative Transfer Model,CRTM)对FY-2F的亮温资料进行了模拟。在有...为了实现西太平洋及东亚区域FY-2F可见红外自旋扫描辐射计(VISSR)资料的直接同化,本文利用飓风天气预报模式(WRF For Hurricane,HWRF)和快速辐射传输模式(Community Radiative Transfer Model,CRTM)对FY-2F的亮温资料进行了模拟。在有云情况下,中高纬度锋面云系模拟的相对较好,而低纬热带云团模拟偏差较大。对于晴空条件下模拟的红外1、2、4通道(IR1、2、4)亮温,受陆地下垫面发射率不均匀的影响模拟偏差较大,且辐射传输模式平均而言低估了地表发射率。海洋下垫面的资料模拟情况要明显好于陆地。IR4通道在白天受太阳短波影响观测亮温偏高。去除受云污染的资料仅保留晴空观测资料,通过格点统计插值(Community Gridpoint Statistical Interpolation,GSI)质量控制和偏差订正,IR2通道平均偏差减小约50%,IR3通道平均偏差从3.7 K减小到0.34 K。而IR1通道质量较好,偏差订正前后几乎没有变化。展开更多
Using the small-slope approximation model of microwave emission of rough sea surface, the impacts of sea surface wind on brightness tem- perature variations generated by the surface rough- ness, i.e. ?Th,v, are invest...Using the small-slope approximation model of microwave emission of rough sea surface, the impacts of sea surface wind on brightness tem- perature variations generated by the surface rough- ness, i.e. ?Th,v, are investigated. Here ?T denotes the brightness temperature variation, and “h” and “v” denote the horizontal and vertical polarizations re- spectively. ?Th,v has a linear relation with wind speed, sea surface temperature (SST) and sea surface sa- linity (SSS) respectively. Further more, the impact of wind direction on SSS retrieval, under small inci- dence angles, can be removed by calculating (?Th+?Tv). These characteristics provide simple new ways to develop an SSS retrieval algorithm without wind direction factor.展开更多
文摘为了给热辐射方向性研究提供准确的组分温度分布和方向亮温数据,提出了一种新的基于热像仪的实用测量方法.该算法包括2个部分:1)采用“热像仪-定面积法”的改进方法“虚拟圈”结合“交叉点法”自动提取植被冠层方向亮度温度,并进行时间效应纠正;2)在假设发射率已知的条件下,利用“开放度”的概念去除多次散射和天空下行辐射的影响,给出更精确的组分温度分布信息.采用2006年4月20日北京小汤山小麦地的测量数据进行了初步分析.获取的方向亮温可以较好地反映地表热辐射方向性规律,热动力学温度提取误差均值小于1 K.
文摘Using the small-slope approximation model of microwave emission of rough sea surface, the impacts of sea surface wind on brightness tem- perature variations generated by the surface rough- ness, i.e. ?Th,v, are investigated. Here ?T denotes the brightness temperature variation, and “h” and “v” denote the horizontal and vertical polarizations re- spectively. ?Th,v has a linear relation with wind speed, sea surface temperature (SST) and sea surface sa- linity (SSS) respectively. Further more, the impact of wind direction on SSS retrieval, under small inci- dence angles, can be removed by calculating (?Th+?Tv). These characteristics provide simple new ways to develop an SSS retrieval algorithm without wind direction factor.