摘要: In AD-A045 247, a set of equations was developed which permits one to calculate acquisition, classification and identification ranges for ship targets when viewed by an airborne forward looking infrared (FLIR) imaging device. In p... 展开 In AD-A045 247, a set of equations was developed which permits one to calculate acquisition, classification and identification ranges for ship targets when viewed by an airborne forward looking infrared (FLIR) imaging device. In performing such calculations, one of the crucial factors is the attentuation by the intervening atmosphere of the infrared radiation emitted by the target and received by the sensor. Atmospheric water vapor, whose concentration is quite variable over time and place, is a principal absorber of infrared radiation over the spectral range of interest. The present report provides, in the forms of histograms and graphs, percent frequencies of occurrence and cumulative percent frequencies of occurrence, respectively of the various concentrations of atmospheric water vapor for each of 21 maritime sites throughout the northern hemisphere over the entire year. Similar data representing a composite over all 21 sites are also given. These data serve as inputs to the mathematical model. 收起