中文摘要：

提出了一种改进的FY-2E红外通道“晴空区”水汽信息提取算法———二次差分法，即在对红外分裂窗云掩图进行分裂窗差分的基础上再进行时间差分处理，或者先进行时间差分后再进行分裂窗差分处理。该方法能减弱晴空区地表温度变化对水汽信息提取的干扰，从而有助于获得水汽团的纹理及其移动信息。实验结果表明，应用该方法可以更加有效地追踪红外通道“晴空区”水汽微弱示踪信号的移动，获得传统云导风方法所无法得到的晴空水汽含量高值区风场信息，且晴空风矢与NCEP（ national centers for environmental prediction）再分析资料级低空风场有着很好的一致性。

英文摘要：

The quadratic difference method, as an improved water vapor signal extraction algorithm, is employed in“clear sky region” from FY -2E infrared channel. By means of both split window and temporal difference calculation from infrared cloud mask images, the method can weaken the surface temperature interference and help trace the weak signal of water vapor in “clear sky region”, regardless of the order of the two calculations. Application examples show that this method can trace the weak signal of water vapor in “clear sky region” more effectively and make up for the lacking wind field data in clear sky with high water vapor content values as compared with the obvious limitation of deriving cloud motion wind by the traditional method. A comparison between the wind fields using this technique and that obtained from the NCEP reanalysis data shows a good relative accuracy.