of  downward  vertical  motion.  Water  vapor  imagery can  detect  these  motions  without  clouds  present. Circulation  patterns  in  the  upper  atmosphere, including the jet stream, are easily identified using WV imagery. Q15. Q16. Q17. Q18. Q19. Q20. Q21. Q22. Q23. Q24. REVIEW  QUESTIONS What is the image-scanning sensor of a satellite called? Which sensor would provide higher resolution data, one with a spatial resolution of 1 kilometer or one with a spatial resolution of 4 kilometers? Consider two objects, one cold the other hot. Which object is emitting electromagnetic energy at relatively longer wavelengths? The majority of the radiation emitted by the earth is known by what term? In the visible spectrum, what color has the longest wavelength? Of the following objects, sand or grass, which one would have a higher albedo? What are the major advantages of infrared imagery? How do relatively cold objects appear on IR imagery? How do high humidity areas appear on water vapor images? What  are  the  advantages  of  water  vapor imagery? IMAGERY  ENHANCEMENT LEARNING  OBJECTIVES:  Identify  various types of user-defined and predefined satellite enhancement  curves. Identify   information contained  in  the  GOES  legend  and  temperature scale. Most satellite data processors have the capability to assign colors or various gray shades to specific JR imagery energy readings. When an image is produced by using either color or an alternating gray shade rather than  the  straight  black-to-white  or  white-to-black shading, the color or gray shade assignment is called an enhancement.  An  enhanced  satellite  image  allows  the user to see specific details of an image with better definition.  Infrared  imagery  is  often  enhanced  to better define a small range of critical temperatures. TYPES OF ENHANCEMENT CURVES Unenhanced imagery displays a linear transition of gray shades from black (warm) to white (cold). It is a steady  increase  in  brightness  that  produces  little contrast. Enhanced imagery displays a transition of mostly  non-linear  gray  shades.  The  result  is  an improved contrast of various key temperatures that makes specific temperature assessment much easier. There are two methods of enhancing satellite imagery: brilliance   inversions   and   thresholding   (curves). Brilliance inversion enhancements use a range of gray shades  (or  color)  to  identify  a  range  of  specific temperatures. With threshold enhancements, a single gray  shade  is  used  to  identify  a  whole  range  of temperatures. In other words, all the temperatures in a particular range have the same gray contour. Figure 1-14 shows enhanced infrared images. User-Defined  Enhancement  Curves When possible, enhancement curves should be locally  developed  and  evaluated.  Most  satellite receiving equipment used by the Navy, such as the AN/SMQ-11,   allow   for   the   creation   of   custom designed enhancement curves. Keep in mind that when  you  are  developing  enhancement  curves,  you should limit the number of features to be enhanced. You must allow for enough detail as possible without making  the  display  too  confusing.  There  are  always compromises between simple enhancement curves, which sacrifice detail but can quickly be interpreted in an operational environment, and complex curves, which maximize information content but require more time to interpret. Figure 1-15 is a graphic illustration of a basic enhancement curve table. Count values as input would be plotted on the horizontal axis, and modified count values for the final display would be plotted on the vertical axis. These count values range from 0 to 255, where 0 appears as black and 255 appears as white. Values in between produce varying shades of gray. By adding, deleting, and positioning points within the graph, an input color or gray shade is mapped to an output color or gray shade. As points of reference, six count values on the horizontal axis correspond to the six sets of temperatures at the bottom of the graph. Count values on the vertical axis result in the gray shade range as referenced at the right of the graph.   The 1-14